OSCL-LXR linux-6.0.1/​fs/​btrfs/​send.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2012 Alexander Block.  All rights reserved.
  */
 
 #include <linux/bsearch.h>
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/sort.h>
 #include <linux/mount.h>
 #include <linux/xattr.h>
 #include <linux/posix_acl_xattr.h>
 #include <linux/radix-tree.h>
 #include <linux/vmalloc.h>
 #include <linux/string.h>
 #include <linux/compat.h>
 #include <linux/crc32c.h>
 
 #include "send.h"
 #include "ctree.h"
 #include "backref.h"
 #include "locking.h"
 #include "disk-io.h"
 #include "btrfs_inode.h"
 #include "transaction.h"
 #include "compression.h"
 #include "xattr.h"
 #include "print-tree.h"
 
 /*
  * Maximum number of references an extent can have in order for us to attempt to
  * issue clone operations instead of write operations. This currently exists to
  * avoid hitting limitations of the backreference walking code (taking a lot of
  * time and using too much memory for extents with large number of references).
  */
 #define SEND_MAX_EXTENT_REFS    64
 
 /*
  * A fs_path is a helper to dynamically build path names with unknown size.
  * It reallocates the internal buffer on demand.
  * It allows fast adding of path elements on the right side (normal path) and
  * fast adding to the left side (reversed path). A reversed path can also be
  * unreversed if needed.
  */
 struct fs_path {
     union {
         struct {
             char *start;
             char *end;
 
             char *buf;
             unsigned short buf_len:15;
             unsigned short reversed:1;
             char inline_buf[];
         };
         /*
          * Average path length does not exceed 200 bytes, we'll have
          * better packing in the slab and higher chance to satisfy
          * a allocation later during send.
          */
         char pad[256];
     };
 };
 #define FS_PATH_INLINE_SIZE \
     (sizeof(struct fs_path) - offsetof(struct fs_path, inline_buf))
 
 
 /* reused for each extent */
 struct clone_root {
     struct btrfs_root *root;
     u64 ino;
     u64 offset;
 
     u64 found_refs;
 };
 
 #define SEND_CTX_MAX_NAME_CACHE_SIZE 128
 #define SEND_CTX_NAME_CACHE_CLEAN_SIZE (SEND_CTX_MAX_NAME_CACHE_SIZE * 2)
 
 struct send_ctx {
     struct file *send_filp;
     loff_t send_off;
     char *send_buf;
     u32 send_size;
     u32 send_max_size;
     /*
      * Whether BTRFS_SEND_A_DATA attribute was already added to current
      * command (since protocol v2, data must be the last attribute).
      */
     bool put_data;
     struct page **send_buf_pages;
     u64 flags;  /* 'flags' member of btrfs_ioctl_send_args is u64 */
     /* Protocol version compatibility requested */
     u32 proto;
 
     struct btrfs_root *send_root;
     struct btrfs_root *parent_root;
     struct clone_root *clone_roots;
     int clone_roots_cnt;
 
     /* current state of the compare_tree call */
     struct btrfs_path *left_path;
     struct btrfs_path *right_path;
     struct btrfs_key *cmp_key;
 
     /*
      * Keep track of the generation of the last transaction that was used
      * for relocating a block group. This is periodically checked in order
      * to detect if a relocation happened since the last check, so that we
      * don't operate on stale extent buffers for nodes (level >= 1) or on
      * stale disk_bytenr values of file extent items.
      */
     u64 last_reloc_trans;
 
     /*
      * infos of the currently processed inode. In case of deleted inodes,
      * these are the values from the deleted inode.
      */
     u64 cur_ino;
     u64 cur_inode_gen;
     u64 cur_inode_size;
     u64 cur_inode_mode;
     u64 cur_inode_rdev;
     u64 cur_inode_last_extent;
     u64 cur_inode_next_write_offset;
     bool cur_inode_new;
     bool cur_inode_new_gen;
     bool cur_inode_deleted;
     bool ignore_cur_inode;
 
     u64 send_progress;
 
     struct list_head new_refs;
     struct list_head deleted_refs;
 
     struct radix_tree_root name_cache;
     struct list_head name_cache_list;
     int name_cache_size;
 
     /*
      * The inode we are currently processing. It's not NULL only when we
      * need to issue write commands for data extents from this inode.
      */
     struct inode *cur_inode;
     struct file_ra_state ra;
     u64 page_cache_clear_start;
     bool clean_page_cache;
 
     /*
      * We process inodes by their increasing order, so if before an
      * incremental send we reverse the parent/child relationship of
      * directories such that a directory with a lower inode number was
      * the parent of a directory with a higher inode number, and the one
      * becoming the new parent got renamed too, we can't rename/move the
      * directory with lower inode number when we finish processing it - we
      * must process the directory with higher inode number first, then
      * rename/move it and then rename/move the directory with lower inode
      * number. Example follows.
      *
      * Tree state when the first send was performed:
      *
      * .
      * |-- a                   (ino 257)
      *     |-- b               (ino 258)
      *         |
      *         |
      *         |-- c           (ino 259)
      *         |   |-- d       (ino 260)
      *         |
      *         |-- c2          (ino 261)
      *
      * Tree state when the second (incremental) send is performed:
      *
      * .
      * |-- a                   (ino 257)
      *     |-- b               (ino 258)
      *         |-- c2          (ino 261)
      *             |-- d2      (ino 260)
      *                 |-- cc  (ino 259)
      *
      * The sequence of steps that lead to the second state was:
      *
      * mv /a/b/c/d /a/b/c2/d2
      * mv /a/b/c /a/b/c2/d2/cc
      *
      * "c" has lower inode number, but we can't move it (2nd mv operation)
      * before we move "d", which has higher inode number.
      *
      * So we just memorize which move/rename operations must be performed
      * later when their respective parent is processed and moved/renamed.
      */
 
     /* Indexed by parent directory inode number. */
     struct rb_root pending_dir_moves;
 
     /*
      * Reverse index, indexed by the inode number of a directory that
      * is waiting for the move/rename of its immediate parent before its
      * own move/rename can be performed.
      */
     struct rb_root waiting_dir_moves;
 
     /*
      * A directory that is going to be rm'ed might have a child directory
      * which is in the pending directory moves index above. In this case,
      * the directory can only be removed after the move/rename of its child
      * is performed. Example:
      *
      * Parent snapshot:
      *
      * .                        (ino 256)
      * |-- a/                   (ino 257)
      *     |-- b/               (ino 258)
      *         |-- c/           (ino 259)
      *         |   |-- x/       (ino 260)
      *         |
      *         |-- y/           (ino 261)
      *
      * Send snapshot:
      *
      * .                        (ino 256)
      * |-- a/                   (ino 257)
      *     |-- b/               (ino 258)
      *         |-- YY/          (ino 261)
      *              |-- x/      (ino 260)
      *
      * Sequence of steps that lead to the send snapshot:
      * rm -f /a/b/c/foo.txt
      * mv /a/b/y /a/b/YY
      * mv /a/b/c/x /a/b/YY
      * rmdir /a/b/c
      *
      * When the child is processed, its move/rename is delayed until its
      * parent is processed (as explained above), but all other operations
      * like update utimes, chown, chgrp, etc, are performed and the paths
      * that it uses for those operations must use the orphanized name of
      * its parent (the directory we're going to rm later), so we need to
      * memorize that name.
      *
      * Indexed by the inode number of the directory to be deleted.
      */
     struct rb_root orphan_dirs;
 
     struct rb_root rbtree_new_refs;
     struct rb_root rbtree_deleted_refs;
 };
 
 struct pending_dir_move {
     struct rb_node node;
     struct list_head list;
     u64 parent_ino;
     u64 ino;
     u64 gen;
     struct list_head update_refs;
 };
 
 struct waiting_dir_move {
     struct rb_node node;
     u64 ino;
     /*
      * There might be some directory that could not be removed because it
      * was waiting for this directory inode to be moved first. Therefore
      * after this directory is moved, we can try to rmdir the ino rmdir_ino.
      */
     u64 rmdir_ino;
     u64 rmdir_gen;
     bool orphanized;
 };
 
 struct orphan_dir_info {
     struct rb_node node;
     u64 ino;
     u64 gen;
     u64 last_dir_index_offset;
 };
 
 struct name_cache_entry {
     struct list_head list;
     /*
      * radix_tree has only 32bit entries but we need to handle 64bit inums.
      * We use the lower 32bit of the 64bit inum to store it in the tree. If
      * more then one inum would fall into the same entry, we use radix_list
      * to store the additional entries. radix_list is also used to store
      * entries where two entries have the same inum but different
      * generations.
      */
     struct list_head radix_list;
     u64 ino;
     u64 gen;
     u64 parent_ino;
     u64 parent_gen;
     int ret;
     int need_later_update;
     int name_len;
     char name[];
 };
 
 #define ADVANCE                         1
 #define ADVANCE_ONLY_NEXT                   -1
 
 enum btrfs_compare_tree_result {
     BTRFS_COMPARE_TREE_NEW,
     BTRFS_COMPARE_TREE_DELETED,
     BTRFS_COMPARE_TREE_CHANGED,
     BTRFS_COMPARE_TREE_SAME,
 };
 
 __cold
 static void inconsistent_snapshot_error(struct send_ctx *sctx,
                     enum btrfs_compare_tree_result result,
                     const char *what)
 {
     const char *result_string;
 
     switch (result) {
     case BTRFS_COMPARE_TREE_NEW:
         result_string = "new";
         break;
     case BTRFS_COMPARE_TREE_DELETED:
         result_string = "deleted";
         break;
     case BTRFS_COMPARE_TREE_CHANGED:
         result_string = "updated";
         break;
     case BTRFS_COMPARE_TREE_SAME:
         ASSERT(0);
         result_string = "unchanged";
         break;
     default:
         ASSERT(0);
         result_string = "unexpected";
     }
 
     btrfs_err(sctx->send_root->fs_info,
           "Send: inconsistent snapshot, found %s %s for inode %llu without updated inode item, send root is %llu, parent root is %llu",
           result_string, what, sctx->cmp_key->objectid,
           sctx->send_root->root_key.objectid,
           (sctx->parent_root ?
            sctx->parent_root->root_key.objectid : 0));
 }
 
 __maybe_unused
 static bool proto_cmd_ok(const struct send_ctx *sctx, int cmd)
 {
     switch (sctx->proto) {
     case 1:  return cmd <= BTRFS_SEND_C_MAX_V1;
     case 2:  return cmd <= BTRFS_SEND_C_MAX_V2;
     default: return false;
     }
 }
 
 static int is_waiting_for_move(struct send_ctx *sctx, u64 ino);
 
 static struct waiting_dir_move *
 get_waiting_dir_move(struct send_ctx *sctx, u64 ino);
 
 static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino, u64 gen);
 
 static int need_send_hole(struct send_ctx *sctx)
 {
     return (sctx->parent_root && !sctx->cur_inode_new &&
         !sctx->cur_inode_new_gen && !sctx->cur_inode_deleted &&
         S_ISREG(sctx->cur_inode_mode));
 }
 
 static void fs_path_reset(struct fs_path *p)
 {
     if (p->reversed) {
         p->start = p->buf + p->buf_len - 1;
         p->end = p->start;
         *p->start = 0;
     } else {
         p->start = p->buf;
         p->end = p->start;
         *p->start = 0;
     }
 }
 
 static struct fs_path *fs_path_alloc(void)
 {
     struct fs_path *p;
 
     p = kmalloc(sizeof(*p), GFP_KERNEL);
     if (!p)
         return NULL;
     p->reversed = 0;
     p->buf = p->inline_buf;
     p->buf_len = FS_PATH_INLINE_SIZE;
     fs_path_reset(p);
     return p;
 }
 
 static struct fs_path *fs_path_alloc_reversed(void)
 {
     struct fs_path *p;
 
     p = fs_path_alloc();
     if (!p)
         return NULL;
     p->reversed = 1;
     fs_path_reset(p);
     return p;
 }
 
 static void fs_path_free(struct fs_path *p)
 {
     if (!p)
         return;
     if (p->buf != p->inline_buf)
         kfree(p->buf);
     kfree(p);
 }
 
 static int fs_path_len(struct fs_path *p)
 {
     return p->end - p->start;
 }
 
 static int fs_path_ensure_buf(struct fs_path *p, int len)
 {
     char *tmp_buf;
     int path_len;
     int old_buf_len;
 
     len++;
 
     if (p->buf_len >= len)
         return 0;
 
     if (len > PATH_MAX) {
         WARN_ON(1);
         return -ENOMEM;
     }
 
     path_len = p->end - p->start;
     old_buf_len = p->buf_len;
 
     /*
      * First time the inline_buf does not suffice
      */
     if (p->buf == p->inline_buf) {
         tmp_buf = kmalloc(len, GFP_KERNEL);
         if (tmp_buf)
             memcpy(tmp_buf, p->buf, old_buf_len);
     } else {
         tmp_buf = krealloc(p->buf, len, GFP_KERNEL);
     }
     if (!tmp_buf)
         return -ENOMEM;
     p->buf = tmp_buf;
     /*
      * The real size of the buffer is bigger, this will let the fast path
      * happen most of the time
      */
     p->buf_len = ksize(p->buf);
 
     if (p->reversed) {
         tmp_buf = p->buf + old_buf_len - path_len - 1;
         p->end = p->buf + p->buf_len - 1;
         p->start = p->end - path_len;
         memmove(p->start, tmp_buf, path_len + 1);
     } else {
         p->start = p->buf;
         p->end = p->start + path_len;
     }
     return 0;
 }
 
 static int fs_path_prepare_for_add(struct fs_path *p, int name_len,
                    char **prepared)
 {
     int ret;
     int new_len;
 
     new_len = p->end - p->start + name_len;
     if (p->start != p->end)
         new_len++;
     ret = fs_path_ensure_buf(p, new_len);
     if (ret < 0)
         goto out;
 
     if (p->reversed) {
         if (p->start != p->end)
             *--p->start = '/';
         p->start -= name_len;
         *prepared = p->start;
     } else {
         if (p->start != p->end)
             *p->end++ = '/';
         *prepared = p->end;
         p->end += name_len;
         *p->end = 0;
     }
 
 out:
     return ret;
 }
 
 static int fs_path_add(struct fs_path *p, const char *name, int name_len)
 {
     int ret;
     char *prepared;
 
     ret = fs_path_prepare_for_add(p, name_len, &prepared);
     if (ret < 0)
         goto out;
     memcpy(prepared, name, name_len);
 
 out:
     return ret;
 }
 
 static int fs_path_add_path(struct fs_path *p, struct fs_path *p2)
 {
     int ret;
     char *prepared;
 
     ret = fs_path_prepare_for_add(p, p2->end - p2->start, &prepared);
     if (ret < 0)
         goto out;
     memcpy(prepared, p2->start, p2->end - p2->start);
 
 out:
     return ret;
 }
 
 static int fs_path_add_from_extent_buffer(struct fs_path *p,
                       struct extent_buffer *eb,
                       unsigned long off, int len)
 {
     int ret;
     char *prepared;
 
     ret = fs_path_prepare_for_add(p, len, &prepared);
     if (ret < 0)
         goto out;
 
     read_extent_buffer(eb, prepared, off, len);
 
 out:
     return ret;
 }
 
 static int fs_path_copy(struct fs_path *p, struct fs_path *from)
 {
     p->reversed = from->reversed;
     fs_path_reset(p);
 
     return fs_path_add_path(p, from);
 }
 
 static void fs_path_unreverse(struct fs_path *p)
 {
     char *tmp;
     int len;
 
     if (!p->reversed)
         return;
 
     tmp = p->start;
     len = p->end - p->start;
     p->start = p->buf;
     p->end = p->start + len;
     memmove(p->start, tmp, len + 1);
     p->reversed = 0;
 }
 
 static struct btrfs_path *alloc_path_for_send(void)
 {
     struct btrfs_path *path;
 
     path = btrfs_alloc_path();
     if (!path)
         return NULL;
     path->search_commit_root = 1;
     path->skip_locking = 1;
     path->need_commit_sem = 1;
     return path;
 }
 
 static int write_buf(struct file *filp, const void *buf, u32 len, loff_t *off)
 {
     int ret;
     u32 pos = 0;
 
     while (pos < len) {
         ret = kernel_write(filp, buf + pos, len - pos, off);
         if (ret < 0)
             return ret;
         if (ret == 0)
             return -EIO;
         pos += ret;
     }
 
     return 0;
 }
 
 static int tlv_put(struct send_ctx *sctx, u16 attr, const void *data, int len)
 {
     struct btrfs_tlv_header *hdr;
     int total_len = sizeof(*hdr) + len;
     int left = sctx->send_max_size - sctx->send_size;
 
     if (WARN_ON_ONCE(sctx->put_data))
         return -EINVAL;
 
     if (unlikely(left < total_len))
         return -EOVERFLOW;
 
     hdr = (struct btrfs_tlv_header *) (sctx->send_buf + sctx->send_size);
     put_unaligned_le16(attr, &hdr->tlv_type);
     put_unaligned_le16(len, &hdr->tlv_len);
     memcpy(hdr + 1, data, len);
     sctx->send_size += total_len;
 
     return 0;
 }
 
 #define TLV_PUT_DEFINE_INT(bits) \
     static int tlv_put_u##bits(struct send_ctx *sctx,       \
             u##bits attr, u##bits value)            \
     {                               \
         __le##bits __tmp = cpu_to_le##bits(value);      \
         return tlv_put(sctx, attr, &__tmp, sizeof(__tmp));  \
     }
 
 TLV_PUT_DEFINE_INT(32)
 TLV_PUT_DEFINE_INT(64)
 
 static int tlv_put_string(struct send_ctx *sctx, u16 attr,
               const char *str, int len)
 {
     if (len == -1)
         len = strlen(str);
     return tlv_put(sctx, attr, str, len);
 }
 
 static int tlv_put_uuid(struct send_ctx *sctx, u16 attr,
             const u8 *uuid)
 {
     return tlv_put(sctx, attr, uuid, BTRFS_UUID_SIZE);
 }
 
 static int tlv_put_btrfs_timespec(struct send_ctx *sctx, u16 attr,
                   struct extent_buffer *eb,
                   struct btrfs_timespec *ts)
 {
     struct btrfs_timespec bts;
     read_extent_buffer(eb, &bts, (unsigned long)ts, sizeof(bts));
     return tlv_put(sctx, attr, &bts, sizeof(bts));
 }
 
 
 #define TLV_PUT(sctx, attrtype, data, attrlen) \
     do { \
         ret = tlv_put(sctx, attrtype, data, attrlen); \
         if (ret < 0) \
             goto tlv_put_failure; \
     } while (0)
 
 #define TLV_PUT_INT(sctx, attrtype, bits, value) \
     do { \
         ret = tlv_put_u##bits(sctx, attrtype, value); \
         if (ret < 0) \
             goto tlv_put_failure; \
     } while (0)
 
 #define TLV_PUT_U8(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 8, data)
 #define TLV_PUT_U16(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 16, data)
 #define TLV_PUT_U32(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 32, data)
 #define TLV_PUT_U64(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 64, data)
 #define TLV_PUT_STRING(sctx, attrtype, str, len) \
     do { \
         ret = tlv_put_string(sctx, attrtype, str, len); \
         if (ret < 0) \
             goto tlv_put_failure; \
     } while (0)
 #define TLV_PUT_PATH(sctx, attrtype, p) \
     do { \
         ret = tlv_put_string(sctx, attrtype, p->start, \
             p->end - p->start); \
         if (ret < 0) \
             goto tlv_put_failure; \
     } while(0)
 #define TLV_PUT_UUID(sctx, attrtype, uuid) \
     do { \
         ret = tlv_put_uuid(sctx, attrtype, uuid); \
         if (ret < 0) \
             goto tlv_put_failure; \
     } while (0)
 #define TLV_PUT_BTRFS_TIMESPEC(sctx, attrtype, eb, ts) \
     do { \
         ret = tlv_put_btrfs_timespec(sctx, attrtype, eb, ts); \
         if (ret < 0) \
             goto tlv_put_failure; \
     } while (0)
 
 static int send_header(struct send_ctx *sctx)
 {
     struct btrfs_stream_header hdr;
 
     strcpy(hdr.magic, BTRFS_SEND_STREAM_MAGIC);
     hdr.version = cpu_to_le32(sctx->proto);
     return write_buf(sctx->send_filp, &hdr, sizeof(hdr),
                     &sctx->send_off);
 }
 
 /*
  * For each command/item we want to send to userspace, we call this function.
  */
 static int begin_cmd(struct send_ctx *sctx, int cmd)
 {
     struct btrfs_cmd_header *hdr;
 
     if (WARN_ON(!sctx->send_buf))
         return -EINVAL;
 
     BUG_ON(sctx->send_size);
 
     sctx->send_size += sizeof(*hdr);
     hdr = (struct btrfs_cmd_header *)sctx->send_buf;
     put_unaligned_le16(cmd, &hdr->cmd);
 
     return 0;
 }
 
 static int send_cmd(struct send_ctx *sctx)
 {
     int ret;
     struct btrfs_cmd_header *hdr;
     u32 crc;
 
     hdr = (struct btrfs_cmd_header *)sctx->send_buf;
     put_unaligned_le32(sctx->send_size - sizeof(*hdr), &hdr->len);
     put_unaligned_le32(0, &hdr->crc);
 
     crc = btrfs_crc32c(0, (unsigned char *)sctx->send_buf, sctx->send_size);
     put_unaligned_le32(crc, &hdr->crc);
 
     ret = write_buf(sctx->send_filp, sctx->send_buf, sctx->send_size,
                     &sctx->send_off);
 
     sctx->send_size = 0;
     sctx->put_data = false;
 
     return ret;
 }
 
 /*
  * Sends a move instruction to user space
  */
 static int send_rename(struct send_ctx *sctx,
              struct fs_path *from, struct fs_path *to)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret;
 
     btrfs_debug(fs_info, "send_rename %s -> %s", from->start, to->start);
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_RENAME);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, from);
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_TO, to);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     return ret;
 }
 
 /*
  * Sends a link instruction to user space
  */
 static int send_link(struct send_ctx *sctx,
              struct fs_path *path, struct fs_path *lnk)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret;
 
     btrfs_debug(fs_info, "send_link %s -> %s", path->start, lnk->start);
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_LINK);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, lnk);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     return ret;
 }
 
 /*
  * Sends an unlink instruction to user space
  */
 static int send_unlink(struct send_ctx *sctx, struct fs_path *path)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret;
 
     btrfs_debug(fs_info, "send_unlink %s", path->start);
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_UNLINK);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     return ret;
 }
 
 /*
  * Sends a rmdir instruction to user space
  */
 static int send_rmdir(struct send_ctx *sctx, struct fs_path *path)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret;
 
     btrfs_debug(fs_info, "send_rmdir %s", path->start);
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_RMDIR);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     return ret;
 }
 
 /*
  * Helper function to retrieve some fields from an inode item.
  */
 static int __get_inode_info(struct btrfs_root *root, struct btrfs_path *path,
               u64 ino, u64 *size, u64 *gen, u64 *mode, u64 *uid,
               u64 *gid, u64 *rdev, u64 *fileattr)
 {
     int ret;
     struct btrfs_inode_item *ii;
     struct btrfs_key key;
 
     key.objectid = ino;
     key.type = BTRFS_INODE_ITEM_KEY;
     key.offset = 0;
     ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
     if (ret) {
         if (ret > 0)
             ret = -ENOENT;
         return ret;
     }
 
     ii = btrfs_item_ptr(path->nodes[0], path->slots[0],
             struct btrfs_inode_item);
     if (size)
         *size = btrfs_inode_size(path->nodes[0], ii);
     if (gen)
         *gen = btrfs_inode_generation(path->nodes[0], ii);
     if (mode)
         *mode = btrfs_inode_mode(path->nodes[0], ii);
     if (uid)
         *uid = btrfs_inode_uid(path->nodes[0], ii);
     if (gid)
         *gid = btrfs_inode_gid(path->nodes[0], ii);
     if (rdev)
         *rdev = btrfs_inode_rdev(path->nodes[0], ii);
     /*
      * Transfer the unchanged u64 value of btrfs_inode_item::flags, that's
      * otherwise logically split to 32/32 parts.
      */
     if (fileattr)
         *fileattr = btrfs_inode_flags(path->nodes[0], ii);
 
     return ret;
 }
 
 static int get_inode_info(struct btrfs_root *root,
               u64 ino, u64 *size, u64 *gen,
               u64 *mode, u64 *uid, u64 *gid,
               u64 *rdev, u64 *fileattr)
 {
     struct btrfs_path *path;
     int ret;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
     ret = __get_inode_info(root, path, ino, size, gen, mode, uid, gid,
                    rdev, fileattr);
     btrfs_free_path(path);
     return ret;
 }
 
 typedef int (*iterate_inode_ref_t)(int num, u64 dir, int index,
                    struct fs_path *p,
                    void *ctx);
 
 /*
  * Helper function to iterate the entries in ONE btrfs_inode_ref or
  * btrfs_inode_extref.
  * The iterate callback may return a non zero value to stop iteration. This can
  * be a negative value for error codes or 1 to simply stop it.
  *
  * path must point to the INODE_REF or INODE_EXTREF when called.
  */
 static int iterate_inode_ref(struct btrfs_root *root, struct btrfs_path *path,
                  struct btrfs_key *found_key, int resolve,
                  iterate_inode_ref_t iterate, void *ctx)
 {
     struct extent_buffer *eb = path->nodes[0];
     struct btrfs_inode_ref *iref;
     struct btrfs_inode_extref *extref;
     struct btrfs_path *tmp_path;
     struct fs_path *p;
     u32 cur = 0;
     u32 total;
     int slot = path->slots[0];
     u32 name_len;
     char *start;
     int ret = 0;
     int num = 0;
     int index;
     u64 dir;
     unsigned long name_off;
     unsigned long elem_size;
     unsigned long ptr;
 
     p = fs_path_alloc_reversed();
     if (!p)
         return -ENOMEM;
 
     tmp_path = alloc_path_for_send();
     if (!tmp_path) {
         fs_path_free(p);
         return -ENOMEM;
     }
 
 
     if (found_key->type == BTRFS_INODE_REF_KEY) {
         ptr = (unsigned long)btrfs_item_ptr(eb, slot,
                             struct btrfs_inode_ref);
         total = btrfs_item_size(eb, slot);
         elem_size = sizeof(*iref);
     } else {
         ptr = btrfs_item_ptr_offset(eb, slot);
         total = btrfs_item_size(eb, slot);
         elem_size = sizeof(*extref);
     }
 
     while (cur < total) {
         fs_path_reset(p);
 
         if (found_key->type == BTRFS_INODE_REF_KEY) {
             iref = (struct btrfs_inode_ref *)(ptr + cur);
             name_len = btrfs_inode_ref_name_len(eb, iref);
             name_off = (unsigned long)(iref + 1);
             index = btrfs_inode_ref_index(eb, iref);
             dir = found_key->offset;
         } else {
             extref = (struct btrfs_inode_extref *)(ptr + cur);
             name_len = btrfs_inode_extref_name_len(eb, extref);
             name_off = (unsigned long)&extref->name;
             index = btrfs_inode_extref_index(eb, extref);
             dir = btrfs_inode_extref_parent(eb, extref);
         }
 
         if (resolve) {
             start = btrfs_ref_to_path(root, tmp_path, name_len,
                           name_off, eb, dir,
                           p->buf, p->buf_len);
             if (IS_ERR(start)) {
                 ret = PTR_ERR(start);
                 goto out;
             }
             if (start < p->buf) {
                 /* overflow , try again with larger buffer */
                 ret = fs_path_ensure_buf(p,
                         p->buf_len + p->buf - start);
                 if (ret < 0)
                     goto out;
                 start = btrfs_ref_to_path(root, tmp_path,
                               name_len, name_off,
                               eb, dir,
                               p->buf, p->buf_len);
                 if (IS_ERR(start)) {
                     ret = PTR_ERR(start);
                     goto out;
                 }
                 BUG_ON(start < p->buf);
             }
             p->start = start;
         } else {
             ret = fs_path_add_from_extent_buffer(p, eb, name_off,
                                  name_len);
             if (ret < 0)
                 goto out;
         }
 
         cur += elem_size + name_len;
         ret = iterate(num, dir, index, p, ctx);
         if (ret)
             goto out;
         num++;
     }
 
 out:
     btrfs_free_path(tmp_path);
     fs_path_free(p);
     return ret;
 }
 
 typedef int (*iterate_dir_item_t)(int num, struct btrfs_key *di_key,
                   const char *name, int name_len,
                   const char *data, int data_len,
                   void *ctx);
 
 /*
  * Helper function to iterate the entries in ONE btrfs_dir_item.
  * The iterate callback may return a non zero value to stop iteration. This can
  * be a negative value for error codes or 1 to simply stop it.
  *
  * path must point to the dir item when called.
  */
 static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
                 iterate_dir_item_t iterate, void *ctx)
 {
     int ret = 0;
     struct extent_buffer *eb;
     struct btrfs_dir_item *di;
     struct btrfs_key di_key;
     char *buf = NULL;
     int buf_len;
     u32 name_len;
     u32 data_len;
     u32 cur;
     u32 len;
     u32 total;
     int slot;
     int num;
 
     /*
      * Start with a small buffer (1 page). If later we end up needing more
      * space, which can happen for xattrs on a fs with a leaf size greater
      * then the page size, attempt to increase the buffer. Typically xattr
      * values are small.
      */
     buf_len = PATH_MAX;
     buf = kmalloc(buf_len, GFP_KERNEL);
     if (!buf) {
         ret = -ENOMEM;
         goto out;
     }
 
     eb = path->nodes[0];
     slot = path->slots[0];
     di = btrfs_item_ptr(eb, slot, struct btrfs_dir_item);
     cur = 0;
     len = 0;
     total = btrfs_item_size(eb, slot);
 
     num = 0;
     while (cur < total) {
         name_len = btrfs_dir_name_len(eb, di);
         data_len = btrfs_dir_data_len(eb, di);
         btrfs_dir_item_key_to_cpu(eb, di, &di_key);
 
         if (btrfs_dir_type(eb, di) == BTRFS_FT_XATTR) {
             if (name_len > XATTR_NAME_MAX) {
                 ret = -ENAMETOOLONG;
                 goto out;
             }
             if (name_len + data_len >
                     BTRFS_MAX_XATTR_SIZE(root->fs_info)) {
                 ret = -E2BIG;
                 goto out;
             }
         } else {
             /*
              * Path too long
              */
             if (name_len + data_len > PATH_MAX) {
                 ret = -ENAMETOOLONG;
                 goto out;
             }
         }
 
         if (name_len + data_len > buf_len) {
             buf_len = name_len + data_len;
             if (is_vmalloc_addr(buf)) {
                 vfree(buf);
                 buf = NULL;
             } else {
                 char *tmp = krealloc(buf, buf_len,
                         GFP_KERNEL | __GFP_NOWARN);
 
                 if (!tmp)
                     kfree(buf);
                 buf = tmp;
             }
             if (!buf) {
                 buf = kvmalloc(buf_len, GFP_KERNEL);
                 if (!buf) {
                     ret = -ENOMEM;
                     goto out;
                 }
             }
         }
 
         read_extent_buffer(eb, buf, (unsigned long)(di + 1),
                 name_len + data_len);
 
         len = sizeof(*di) + name_len + data_len;
         di = (struct btrfs_dir_item *)((char *)di + len);
         cur += len;
 
         ret = iterate(num, &di_key, buf, name_len, buf + name_len,
                   data_len, ctx);
         if (ret < 0)
             goto out;
         if (ret) {
             ret = 0;
             goto out;
         }
 
         num++;
     }
 
 out:
     kvfree(buf);
     return ret;
 }
 
 static int __copy_first_ref(int num, u64 dir, int index,
                 struct fs_path *p, void *ctx)
 {
     int ret;
     struct fs_path *pt = ctx;
 
     ret = fs_path_copy(pt, p);
     if (ret < 0)
         return ret;
 
     /* we want the first only */
     return 1;
 }
 
 /*
  * Retrieve the first path of an inode. If an inode has more then one
  * ref/hardlink, this is ignored.
  */
 static int get_inode_path(struct btrfs_root *root,
               u64 ino, struct fs_path *path)
 {
     int ret;
     struct btrfs_key key, found_key;
     struct btrfs_path *p;
 
     p = alloc_path_for_send();
     if (!p)
         return -ENOMEM;
 
     fs_path_reset(path);
 
     key.objectid = ino;
     key.type = BTRFS_INODE_REF_KEY;
     key.offset = 0;
 
     ret = btrfs_search_slot_for_read(root, &key, p, 1, 0);
     if (ret < 0)
         goto out;
     if (ret) {
         ret = 1;
         goto out;
     }
     btrfs_item_key_to_cpu(p->nodes[0], &found_key, p->slots[0]);
     if (found_key.objectid != ino ||
         (found_key.type != BTRFS_INODE_REF_KEY &&
          found_key.type != BTRFS_INODE_EXTREF_KEY)) {
         ret = -ENOENT;
         goto out;
     }
 
     ret = iterate_inode_ref(root, p, &found_key, 1,
                 __copy_first_ref, path);
     if (ret < 0)
         goto out;
     ret = 0;
 
 out:
     btrfs_free_path(p);
     return ret;
 }
 
 struct backref_ctx {
     struct send_ctx *sctx;
 
     /* number of total found references */
     u64 found;
 
     /*
      * used for clones found in send_root. clones found behind cur_objectid
      * and cur_offset are not considered as allowed clones.
      */
     u64 cur_objectid;
     u64 cur_offset;
 
     /* may be truncated in case it's the last extent in a file */
     u64 extent_len;
 
     /* Just to check for bugs in backref resolving */
     int found_itself;
 };
 
 static int __clone_root_cmp_bsearch(const void *key, const void *elt)
 {
     u64 root = (u64)(uintptr_t)key;
     const struct clone_root *cr = elt;
 
     if (root < cr->root->root_key.objectid)
         return -1;
     if (root > cr->root->root_key.objectid)
         return 1;
     return 0;
 }
 
 static int __clone_root_cmp_sort(const void *e1, const void *e2)
 {
     const struct clone_root *cr1 = e1;
     const struct clone_root *cr2 = e2;
 
     if (cr1->root->root_key.objectid < cr2->root->root_key.objectid)
         return -1;
     if (cr1->root->root_key.objectid > cr2->root->root_key.objectid)
         return 1;
     return 0;
 }
 
 /*
  * Called for every backref that is found for the current extent.
  * Results are collected in sctx->clone_roots->ino/offset/found_refs
  */
 static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_)
 {
     struct backref_ctx *bctx = ctx_;
     struct clone_root *found;
 
     /* First check if the root is in the list of accepted clone sources */
     found = bsearch((void *)(uintptr_t)root, bctx->sctx->clone_roots,
             bctx->sctx->clone_roots_cnt,
             sizeof(struct clone_root),
             __clone_root_cmp_bsearch);
     if (!found)
         return 0;
 
     if (found->root == bctx->sctx->send_root &&
         ino == bctx->cur_objectid &&
         offset == bctx->cur_offset) {
         bctx->found_itself = 1;
     }
 
     /*
      * Make sure we don't consider clones from send_root that are
      * behind the current inode/offset.
      */
     if (found->root == bctx->sctx->send_root) {
         /*
          * If the source inode was not yet processed we can't issue a
          * clone operation, as the source extent does not exist yet at
          * the destination of the stream.
          */
         if (ino > bctx->cur_objectid)
             return 0;
         /*
          * We clone from the inode currently being sent as long as the
          * source extent is already processed, otherwise we could try
          * to clone from an extent that does not exist yet at the
          * destination of the stream.
          */
         if (ino == bctx->cur_objectid &&
             offset + bctx->extent_len >
             bctx->sctx->cur_inode_next_write_offset)
             return 0;
     }
 
     bctx->found++;
     found->found_refs++;
     if (ino < found->ino) {
         found->ino = ino;
         found->offset = offset;
     } else if (found->ino == ino) {
         /*
          * same extent found more then once in the same file.
          */
         if (found->offset > offset + bctx->extent_len)
             found->offset = offset;
     }
 
     return 0;
 }
 
 /*
  * Given an inode, offset and extent item, it finds a good clone for a clone
  * instruction. Returns -ENOENT when none could be found. The function makes
  * sure that the returned clone is usable at the point where sending is at the
  * moment. This means, that no clones are accepted which lie behind the current
  * inode+offset.
  *
  * path must point to the extent item when called.
  */
 static int find_extent_clone(struct send_ctx *sctx,
                  struct btrfs_path *path,
                  u64 ino, u64 data_offset,
                  u64 ino_size,
                  struct clone_root **found)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret;
     int extent_type;
     u64 logical;
     u64 disk_byte;
     u64 num_bytes;
     u64 extent_item_pos;
     u64 flags = 0;
     struct btrfs_file_extent_item *fi;
     struct extent_buffer *eb = path->nodes[0];
     struct backref_ctx backref_ctx = {0};
     struct clone_root *cur_clone_root;
     struct btrfs_key found_key;
     struct btrfs_path *tmp_path;
     struct btrfs_extent_item *ei;
     int compressed;
     u32 i;
 
     tmp_path = alloc_path_for_send();
     if (!tmp_path)
         return -ENOMEM;
 
     /* We only use this path under the commit sem */
     tmp_path->need_commit_sem = 0;
 
     if (data_offset >= ino_size) {
         /*
          * There may be extents that lie behind the file's size.
          * I at least had this in combination with snapshotting while
          * writing large files.
          */
         ret = 0;
         goto out;
     }
 
     fi = btrfs_item_ptr(eb, path->slots[0],
             struct btrfs_file_extent_item);
     extent_type = btrfs_file_extent_type(eb, fi);
     if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
         ret = -ENOENT;
         goto out;
     }
     compressed = btrfs_file_extent_compression(eb, fi);
 
     num_bytes = btrfs_file_extent_num_bytes(eb, fi);
     disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
     if (disk_byte == 0) {
         ret = -ENOENT;
         goto out;
     }
     logical = disk_byte + btrfs_file_extent_offset(eb, fi);
 
     down_read(&fs_info->commit_root_sem);
     ret = extent_from_logical(fs_info, disk_byte, tmp_path,
                   &found_key, &flags);
     up_read(&fs_info->commit_root_sem);
 
     if (ret < 0)
         goto out;
     if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
         ret = -EIO;
         goto out;
     }
 
     ei = btrfs_item_ptr(tmp_path->nodes[0], tmp_path->slots[0],
                 struct btrfs_extent_item);
     /*
      * Backreference walking (iterate_extent_inodes() below) is currently
      * too expensive when an extent has a large number of references, both
      * in time spent and used memory. So for now just fallback to write
      * operations instead of clone operations when an extent has more than
      * a certain amount of references.
      */
     if (btrfs_extent_refs(tmp_path->nodes[0], ei) > SEND_MAX_EXTENT_REFS) {
         ret = -ENOENT;
         goto out;
     }
     btrfs_release_path(tmp_path);
 
     /*
      * Setup the clone roots.
      */
     for (i = 0; i < sctx->clone_roots_cnt; i++) {
         cur_clone_root = sctx->clone_roots + i;
         cur_clone_root->ino = (u64)-1;
         cur_clone_root->offset = 0;
         cur_clone_root->found_refs = 0;
     }
 
     backref_ctx.sctx = sctx;
     backref_ctx.found = 0;
     backref_ctx.cur_objectid = ino;
     backref_ctx.cur_offset = data_offset;
     backref_ctx.found_itself = 0;
     backref_ctx.extent_len = num_bytes;
 
     /*
      * The last extent of a file may be too large due to page alignment.
      * We need to adjust extent_len in this case so that the checks in
      * __iterate_backrefs work.
      */
     if (data_offset + num_bytes >= ino_size)
         backref_ctx.extent_len = ino_size - data_offset;
 
     /*
      * Now collect all backrefs.
      */
     if (compressed == BTRFS_COMPRESS_NONE)
         extent_item_pos = logical - found_key.objectid;
     else
         extent_item_pos = 0;
     ret = iterate_extent_inodes(fs_info, found_key.objectid,
                     extent_item_pos, 1, __iterate_backrefs,
                     &backref_ctx, false);
 
     if (ret < 0)
         goto out;
 
     down_read(&fs_info->commit_root_sem);
     if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
         /*
          * A transaction commit for a transaction in which block group
          * relocation was done just happened.
          * The disk_bytenr of the file extent item we processed is
          * possibly stale, referring to the extent's location before
          * relocation. So act as if we haven't found any clone sources
          * and fallback to write commands, which will read the correct
          * data from the new extent location. Otherwise we will fail
          * below because we haven't found our own back reference or we
          * could be getting incorrect sources in case the old extent
          * was already reallocated after the relocation.
          */
         up_read(&fs_info->commit_root_sem);
         ret = -ENOENT;
         goto out;
     }
     up_read(&fs_info->commit_root_sem);
 
     if (!backref_ctx.found_itself) {
         /* found a bug in backref code? */
         ret = -EIO;
         btrfs_err(fs_info,
               "did not find backref in send_root. inode=%llu, offset=%llu, disk_byte=%llu found extent=%llu",
               ino, data_offset, disk_byte, found_key.objectid);
         goto out;
     }
 
     btrfs_debug(fs_info,
             "find_extent_clone: data_offset=%llu, ino=%llu, num_bytes=%llu, logical=%llu",
             data_offset, ino, num_bytes, logical);
 
     if (!backref_ctx.found)
         btrfs_debug(fs_info, "no clones found");
 
     cur_clone_root = NULL;
     for (i = 0; i < sctx->clone_roots_cnt; i++) {
         if (sctx->clone_roots[i].found_refs) {
             if (!cur_clone_root)
                 cur_clone_root = sctx->clone_roots + i;
             else if (sctx->clone_roots[i].root == sctx->send_root)
                 /* prefer clones from send_root over others */
                 cur_clone_root = sctx->clone_roots + i;
         }
 
     }
 
     if (cur_clone_root) {
         *found = cur_clone_root;
         ret = 0;
     } else {
         ret = -ENOENT;
     }
 
 out:
     btrfs_free_path(tmp_path);
     return ret;
 }
 
 static int read_symlink(struct btrfs_root *root,
             u64 ino,
             struct fs_path *dest)
 {
     int ret;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_file_extent_item *ei;
     u8 type;
     u8 compression;
     unsigned long off;
     int len;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     key.objectid = ino;
     key.type = BTRFS_EXTENT_DATA_KEY;
     key.offset = 0;
     ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
     if (ret < 0)
         goto out;
     if (ret) {
         /*
          * An empty symlink inode. Can happen in rare error paths when
          * creating a symlink (transaction committed before the inode
          * eviction handler removed the symlink inode items and a crash
          * happened in between or the subvol was snapshoted in between).
          * Print an informative message to dmesg/syslog so that the user
          * can delete the symlink.
          */
         btrfs_err(root->fs_info,
               "Found empty symlink inode %llu at root %llu",
               ino, root->root_key.objectid);
         ret = -EIO;
         goto out;
     }
 
     ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
             struct btrfs_file_extent_item);
     type = btrfs_file_extent_type(path->nodes[0], ei);
     compression = btrfs_file_extent_compression(path->nodes[0], ei);
     BUG_ON(type != BTRFS_FILE_EXTENT_INLINE);
     BUG_ON(compression);
 
     off = btrfs_file_extent_inline_start(ei);
     len = btrfs_file_extent_ram_bytes(path->nodes[0], ei);
 
     ret = fs_path_add_from_extent_buffer(dest, path->nodes[0], off, len);
 
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * Helper function to generate a file name that is unique in the root of
  * send_root and parent_root. This is used to generate names for orphan inodes.
  */
 static int gen_unique_name(struct send_ctx *sctx,
                u64 ino, u64 gen,
                struct fs_path *dest)
 {
     int ret = 0;
     struct btrfs_path *path;
     struct btrfs_dir_item *di;
     char tmp[64];
     int len;
     u64 idx = 0;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     while (1) {
         len = snprintf(tmp, sizeof(tmp), "o%llu-%llu-%llu",
                 ino, gen, idx);
         ASSERT(len < sizeof(tmp));
 
         di = btrfs_lookup_dir_item(NULL, sctx->send_root,
                 path, BTRFS_FIRST_FREE_OBJECTID,
                 tmp, strlen(tmp), 0);
         btrfs_release_path(path);
         if (IS_ERR(di)) {
             ret = PTR_ERR(di);
             goto out;
         }
         if (di) {
             /* not unique, try again */
             idx++;
             continue;
         }
 
         if (!sctx->parent_root) {
             /* unique */
             ret = 0;
             break;
         }
 
         di = btrfs_lookup_dir_item(NULL, sctx->parent_root,
                 path, BTRFS_FIRST_FREE_OBJECTID,
                 tmp, strlen(tmp), 0);
         btrfs_release_path(path);
         if (IS_ERR(di)) {
             ret = PTR_ERR(di);
             goto out;
         }
         if (di) {
             /* not unique, try again */
             idx++;
             continue;
         }
         /* unique */
         break;
     }
 
     ret = fs_path_add(dest, tmp, strlen(tmp));
 
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 enum inode_state {
     inode_state_no_change,
     inode_state_will_create,
     inode_state_did_create,
     inode_state_will_delete,
     inode_state_did_delete,
 };
 
 static int get_cur_inode_state(struct send_ctx *sctx, u64 ino, u64 gen)
 {
     int ret;
     int left_ret;
     int right_ret;
     u64 left_gen;
     u64 right_gen;
 
     ret = get_inode_info(sctx->send_root, ino, NULL, &left_gen, NULL, NULL,
             NULL, NULL, NULL);
     if (ret < 0 && ret != -ENOENT)
         goto out;
     left_ret = ret;
 
     if (!sctx->parent_root) {
         right_ret = -ENOENT;
     } else {
         ret = get_inode_info(sctx->parent_root, ino, NULL, &right_gen,
                 NULL, NULL, NULL, NULL, NULL);
         if (ret < 0 && ret != -ENOENT)
             goto out;
         right_ret = ret;
     }
 
     if (!left_ret && !right_ret) {
         if (left_gen == gen && right_gen == gen) {
             ret = inode_state_no_change;
         } else if (left_gen == gen) {
             if (ino < sctx->send_progress)
                 ret = inode_state_did_create;
             else
                 ret = inode_state_will_create;
         } else if (right_gen == gen) {
             if (ino < sctx->send_progress)
                 ret = inode_state_did_delete;
             else
                 ret = inode_state_will_delete;
         } else  {
             ret = -ENOENT;
         }
     } else if (!left_ret) {
         if (left_gen == gen) {
             if (ino < sctx->send_progress)
                 ret = inode_state_did_create;
             else
                 ret = inode_state_will_create;
         } else {
             ret = -ENOENT;
         }
     } else if (!right_ret) {
         if (right_gen == gen) {
             if (ino < sctx->send_progress)
                 ret = inode_state_did_delete;
             else
                 ret = inode_state_will_delete;
         } else {
             ret = -ENOENT;
         }
     } else {
         ret = -ENOENT;
     }
 
 out:
     return ret;
 }
 
 static int is_inode_existent(struct send_ctx *sctx, u64 ino, u64 gen)
 {
     int ret;
 
     if (ino == BTRFS_FIRST_FREE_OBJECTID)
         return 1;
 
     ret = get_cur_inode_state(sctx, ino, gen);
     if (ret < 0)
         goto out;
 
     if (ret == inode_state_no_change ||
         ret == inode_state_did_create ||
         ret == inode_state_will_delete)
         ret = 1;
     else
         ret = 0;
 
 out:
     return ret;
 }
 
 /*
  * Helper function to lookup a dir item in a dir.
  */
 static int lookup_dir_item_inode(struct btrfs_root *root,
                  u64 dir, const char *name, int name_len,
                  u64 *found_inode)
 {
     int ret = 0;
     struct btrfs_dir_item *di;
     struct btrfs_key key;
     struct btrfs_path *path;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     di = btrfs_lookup_dir_item(NULL, root, path,
             dir, name, name_len, 0);
     if (IS_ERR_OR_NULL(di)) {
         ret = di ? PTR_ERR(di) : -ENOENT;
         goto out;
     }
     btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
     if (key.type == BTRFS_ROOT_ITEM_KEY) {
         ret = -ENOENT;
         goto out;
     }
     *found_inode = key.objectid;
 
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * Looks up the first btrfs_inode_ref of a given ino. It returns the parent dir,
  * generation of the parent dir and the name of the dir entry.
  */
 static int get_first_ref(struct btrfs_root *root, u64 ino,
              u64 *dir, u64 *dir_gen, struct fs_path *name)
 {
     int ret;
     struct btrfs_key key;
     struct btrfs_key found_key;
     struct btrfs_path *path;
     int len;
     u64 parent_dir;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     key.objectid = ino;
     key.type = BTRFS_INODE_REF_KEY;
     key.offset = 0;
 
     ret = btrfs_search_slot_for_read(root, &key, path, 1, 0);
     if (ret < 0)
         goto out;
     if (!ret)
         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
                 path->slots[0]);
     if (ret || found_key.objectid != ino ||
         (found_key.type != BTRFS_INODE_REF_KEY &&
          found_key.type != BTRFS_INODE_EXTREF_KEY)) {
         ret = -ENOENT;
         goto out;
     }
 
     if (found_key.type == BTRFS_INODE_REF_KEY) {
         struct btrfs_inode_ref *iref;
         iref = btrfs_item_ptr(path->nodes[0], path->slots[0],
                       struct btrfs_inode_ref);
         len = btrfs_inode_ref_name_len(path->nodes[0], iref);
         ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
                              (unsigned long)(iref + 1),
                              len);
         parent_dir = found_key.offset;
     } else {
         struct btrfs_inode_extref *extref;
         extref = btrfs_item_ptr(path->nodes[0], path->slots[0],
                     struct btrfs_inode_extref);
         len = btrfs_inode_extref_name_len(path->nodes[0], extref);
         ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
                     (unsigned long)&extref->name, len);
         parent_dir = btrfs_inode_extref_parent(path->nodes[0], extref);
     }
     if (ret < 0)
         goto out;
     btrfs_release_path(path);
 
     if (dir_gen) {
         ret = get_inode_info(root, parent_dir, NULL, dir_gen, NULL,
                      NULL, NULL, NULL, NULL);
         if (ret < 0)
             goto out;
     }
 
     *dir = parent_dir;
 
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int is_first_ref(struct btrfs_root *root,
             u64 ino, u64 dir,
             const char *name, int name_len)
 {
     int ret;
     struct fs_path *tmp_name;
     u64 tmp_dir;
 
     tmp_name = fs_path_alloc();
     if (!tmp_name)
         return -ENOMEM;
 
     ret = get_first_ref(root, ino, &tmp_dir, NULL, tmp_name);
     if (ret < 0)
         goto out;
 
     if (dir != tmp_dir || name_len != fs_path_len(tmp_name)) {
         ret = 0;
         goto out;
     }
 
     ret = !memcmp(tmp_name->start, name, name_len);
 
 out:
     fs_path_free(tmp_name);
     return ret;
 }
 
 /*
  * Used by process_recorded_refs to determine if a new ref would overwrite an
  * already existing ref. In case it detects an overwrite, it returns the
  * inode/gen in who_ino/who_gen.
  * When an overwrite is detected, process_recorded_refs does proper orphanizing
  * to make sure later references to the overwritten inode are possible.
  * Orphanizing is however only required for the first ref of an inode.
  * process_recorded_refs does an additional is_first_ref check to see if
  * orphanizing is really required.
  */
 static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen,
                   const char *name, int name_len,
                   u64 *who_ino, u64 *who_gen, u64 *who_mode)
 {
     int ret = 0;
     u64 gen;
     u64 other_inode = 0;
 
     if (!sctx->parent_root)
         goto out;
 
     ret = is_inode_existent(sctx, dir, dir_gen);
     if (ret <= 0)
         goto out;
 
     /*
      * If we have a parent root we need to verify that the parent dir was
      * not deleted and then re-created, if it was then we have no overwrite
      * and we can just unlink this entry.
      */
     if (sctx->parent_root && dir != BTRFS_FIRST_FREE_OBJECTID) {
         ret = get_inode_info(sctx->parent_root, dir, NULL, &gen, NULL,
                      NULL, NULL, NULL, NULL);
         if (ret < 0 && ret != -ENOENT)
             goto out;
         if (ret) {
             ret = 0;
             goto out;
         }
         if (gen != dir_gen)
             goto out;
     }
 
     ret = lookup_dir_item_inode(sctx->parent_root, dir, name, name_len,
                     &other_inode);
     if (ret < 0 && ret != -ENOENT)
         goto out;
     if (ret) {
         ret = 0;
         goto out;
     }
 
     /*
      * Check if the overwritten ref was already processed. If yes, the ref
      * was already unlinked/moved, so we can safely assume that we will not
      * overwrite anything at this point in time.
      */
     if (other_inode > sctx->send_progress ||
         is_waiting_for_move(sctx, other_inode)) {
         ret = get_inode_info(sctx->parent_root, other_inode, NULL,
                 who_gen, who_mode, NULL, NULL, NULL, NULL);
         if (ret < 0)
             goto out;
 
         ret = 1;
         *who_ino = other_inode;
     } else {
         ret = 0;
     }
 
 out:
     return ret;
 }
 
 /*
  * Checks if the ref was overwritten by an already processed inode. This is
  * used by __get_cur_name_and_parent to find out if the ref was orphanized and
  * thus the orphan name needs be used.
  * process_recorded_refs also uses it to avoid unlinking of refs that were
  * overwritten.
  */
 static int did_overwrite_ref(struct send_ctx *sctx,
                 u64 dir, u64 dir_gen,
                 u64 ino, u64 ino_gen,
                 const char *name, int name_len)
 {
     int ret = 0;
     u64 gen;
     u64 ow_inode;
 
     if (!sctx->parent_root)
         goto out;
 
     ret = is_inode_existent(sctx, dir, dir_gen);
     if (ret <= 0)
         goto out;
 
     if (dir != BTRFS_FIRST_FREE_OBJECTID) {
         ret = get_inode_info(sctx->send_root, dir, NULL, &gen, NULL,
                      NULL, NULL, NULL, NULL);
         if (ret < 0 && ret != -ENOENT)
             goto out;
         if (ret) {
             ret = 0;
             goto out;
         }
         if (gen != dir_gen)
             goto out;
     }
 
     /* check if the ref was overwritten by another ref */
     ret = lookup_dir_item_inode(sctx->send_root, dir, name, name_len,
                     &ow_inode);
     if (ret < 0 && ret != -ENOENT)
         goto out;
     if (ret) {
         /* was never and will never be overwritten */
         ret = 0;
         goto out;
     }
 
     ret = get_inode_info(sctx->send_root, ow_inode, NULL, &gen, NULL, NULL,
             NULL, NULL, NULL);
     if (ret < 0)
         goto out;
 
     if (ow_inode == ino && gen == ino_gen) {
         ret = 0;
         goto out;
     }
 
     /*
      * We know that it is or will be overwritten. Check this now.
      * The current inode being processed might have been the one that caused
      * inode 'ino' to be orphanized, therefore check if ow_inode matches
      * the current inode being processed.
      */
     if ((ow_inode < sctx->send_progress) ||
         (ino != sctx->cur_ino && ow_inode == sctx->cur_ino &&
          gen == sctx->cur_inode_gen))
         ret = 1;
     else
         ret = 0;
 
 out:
     return ret;
 }
 
 /*
  * Same as did_overwrite_ref, but also checks if it is the first ref of an inode
  * that got overwritten. This is used by process_recorded_refs to determine
  * if it has to use the path as returned by get_cur_path or the orphan name.
  */
 static int did_overwrite_first_ref(struct send_ctx *sctx, u64 ino, u64 gen)
 {
     int ret = 0;
     struct fs_path *name = NULL;
     u64 dir;
     u64 dir_gen;
 
     if (!sctx->parent_root)
         goto out;
 
     name = fs_path_alloc();
     if (!name)
         return -ENOMEM;
 
     ret = get_first_ref(sctx->parent_root, ino, &dir, &dir_gen, name);
     if (ret < 0)
         goto out;
 
     ret = did_overwrite_ref(sctx, dir, dir_gen, ino, gen,
             name->start, fs_path_len(name));
 
 out:
     fs_path_free(name);
     return ret;
 }
 
 /*
  * Insert a name cache entry. On 32bit kernels the radix tree index is 32bit,
  * so we need to do some special handling in case we have clashes. This function
  * takes care of this with the help of name_cache_entry::radix_list.
  * In case of error, nce is kfreed.
  */
 static int name_cache_insert(struct send_ctx *sctx,
                  struct name_cache_entry *nce)
 {
     int ret = 0;
     struct list_head *nce_head;
 
     nce_head = radix_tree_lookup(&sctx->name_cache,
             (unsigned long)nce->ino);
     if (!nce_head) {
         nce_head = kmalloc(sizeof(*nce_head), GFP_KERNEL);
         if (!nce_head) {
             kfree(nce);
             return -ENOMEM;
         }
         INIT_LIST_HEAD(nce_head);
 
         ret = radix_tree_insert(&sctx->name_cache, nce->ino, nce_head);
         if (ret < 0) {
             kfree(nce_head);
             kfree(nce);
             return ret;
         }
     }
     list_add_tail(&nce->radix_list, nce_head);
     list_add_tail(&nce->list, &sctx->name_cache_list);
     sctx->name_cache_size++;
 
     return ret;
 }
 
 static void name_cache_delete(struct send_ctx *sctx,
                   struct name_cache_entry *nce)
 {
     struct list_head *nce_head;
 
     nce_head = radix_tree_lookup(&sctx->name_cache,
             (unsigned long)nce->ino);
     if (!nce_head) {
         btrfs_err(sctx->send_root->fs_info,
           "name_cache_delete lookup failed ino %llu cache size %d, leaking memory",
             nce->ino, sctx->name_cache_size);
     }
 
     list_del(&nce->radix_list);
     list_del(&nce->list);
     sctx->name_cache_size--;
 
     /*
      * We may not get to the final release of nce_head if the lookup fails
      */
     if (nce_head && list_empty(nce_head)) {
         radix_tree_delete(&sctx->name_cache, (unsigned long)nce->ino);
         kfree(nce_head);
     }
 }
 
 static struct name_cache_entry *name_cache_search(struct send_ctx *sctx,
                             u64 ino, u64 gen)
 {
     struct list_head *nce_head;
     struct name_cache_entry *cur;
 
     nce_head = radix_tree_lookup(&sctx->name_cache, (unsigned long)ino);
     if (!nce_head)
         return NULL;
 
     list_for_each_entry(cur, nce_head, radix_list) {
         if (cur->ino == ino && cur->gen == gen)
             return cur;
     }
     return NULL;
 }
 
 /*
  * Remove some entries from the beginning of name_cache_list.
  */
 static void name_cache_clean_unused(struct send_ctx *sctx)
 {
     struct name_cache_entry *nce;
 
     if (sctx->name_cache_size < SEND_CTX_NAME_CACHE_CLEAN_SIZE)
         return;
 
     while (sctx->name_cache_size > SEND_CTX_MAX_NAME_CACHE_SIZE) {
         nce = list_entry(sctx->name_cache_list.next,
                 struct name_cache_entry, list);
         name_cache_delete(sctx, nce);
         kfree(nce);
     }
 }
 
 static void name_cache_free(struct send_ctx *sctx)
 {
     struct name_cache_entry *nce;
 
     while (!list_empty(&sctx->name_cache_list)) {
         nce = list_entry(sctx->name_cache_list.next,
                 struct name_cache_entry, list);
         name_cache_delete(sctx, nce);
         kfree(nce);
     }
 }
 
 /*
  * Used by get_cur_path for each ref up to the root.
  * Returns 0 if it succeeded.
  * Returns 1 if the inode is not existent or got overwritten. In that case, the
  * name is an orphan name. This instructs get_cur_path to stop iterating. If 1
  * is returned, parent_ino/parent_gen are not guaranteed to be valid.
  * Returns <0 in case of error.
  */
 static int __get_cur_name_and_parent(struct send_ctx *sctx,
                      u64 ino, u64 gen,
                      u64 *parent_ino,
                      u64 *parent_gen,
                      struct fs_path *dest)
 {
     int ret;
     int nce_ret;
     struct name_cache_entry *nce = NULL;
 
     /*
      * First check if we already did a call to this function with the same
      * ino/gen. If yes, check if the cache entry is still up-to-date. If yes
      * return the cached result.
      */
     nce = name_cache_search(sctx, ino, gen);
     if (nce) {
         if (ino < sctx->send_progress && nce->need_later_update) {
             name_cache_delete(sctx, nce);
             kfree(nce);
             nce = NULL;
         } else {
             /*
              * Removes the entry from the list and adds it back to
              * the end.  This marks the entry as recently used so
              * that name_cache_clean_unused does not remove it.
              */
             list_move_tail(&nce->list, &sctx->name_cache_list);
 
             *parent_ino = nce->parent_ino;
             *parent_gen = nce->parent_gen;
             ret = fs_path_add(dest, nce->name, nce->name_len);
             if (ret < 0)
                 goto out;
             ret = nce->ret;
             goto out;
         }
     }
 
     /*
      * If the inode is not existent yet, add the orphan name and return 1.
      * This should only happen for the parent dir that we determine in
      * record_new_ref_if_needed().
      */
     ret = is_inode_existent(sctx, ino, gen);
     if (ret < 0)
         goto out;
 
     if (!ret) {
         ret = gen_unique_name(sctx, ino, gen, dest);
         if (ret < 0)
             goto out;
         ret = 1;
         goto out_cache;
     }
 
     /*
      * Depending on whether the inode was already processed or not, use
      * send_root or parent_root for ref lookup.
      */
     if (ino < sctx->send_progress)
         ret = get_first_ref(sctx->send_root, ino,
                     parent_ino, parent_gen, dest);
     else
         ret = get_first_ref(sctx->parent_root, ino,
                     parent_ino, parent_gen, dest);
     if (ret < 0)
         goto out;
 
     /*
      * Check if the ref was overwritten by an inode's ref that was processed
      * earlier. If yes, treat as orphan and return 1.
      */
     ret = did_overwrite_ref(sctx, *parent_ino, *parent_gen, ino, gen,
             dest->start, dest->end - dest->start);
     if (ret < 0)
         goto out;
     if (ret) {
         fs_path_reset(dest);
         ret = gen_unique_name(sctx, ino, gen, dest);
         if (ret < 0)
             goto out;
         ret = 1;
     }
 
 out_cache:
     /*
      * Store the result of the lookup in the name cache.
      */
     nce = kmalloc(sizeof(*nce) + fs_path_len(dest) + 1, GFP_KERNEL);
     if (!nce) {
         ret = -ENOMEM;
         goto out;
     }
 
     nce->ino = ino;
     nce->gen = gen;
     nce->parent_ino = *parent_ino;
     nce->parent_gen = *parent_gen;
     nce->name_len = fs_path_len(dest);
     nce->ret = ret;
     strcpy(nce->name, dest->start);
 
     if (ino < sctx->send_progress)
         nce->need_later_update = 0;
     else
         nce->need_later_update = 1;
 
     nce_ret = name_cache_insert(sctx, nce);
     if (nce_ret < 0)
         ret = nce_ret;
     name_cache_clean_unused(sctx);
 
 out:
     return ret;
 }
 
 /*
  * Magic happens here. This function returns the first ref to an inode as it
  * would look like while receiving the stream at this point in time.
  * We walk the path up to the root. For every inode in between, we check if it
  * was already processed/sent. If yes, we continue with the parent as found
  * in send_root. If not, we continue with the parent as found in parent_root.
  * If we encounter an inode that was deleted at this point in time, we use the
  * inodes "orphan" name instead of the real name and stop. Same with new inodes
  * that were not created yet and overwritten inodes/refs.
  *
  * When do we have orphan inodes:
  * 1. When an inode is freshly created and thus no valid refs are available yet
  * 2. When a directory lost all it's refs (deleted) but still has dir items
  *    inside which were not processed yet (pending for move/delete). If anyone
  *    tried to get the path to the dir items, it would get a path inside that
  *    orphan directory.
  * 3. When an inode is moved around or gets new links, it may overwrite the ref
  *    of an unprocessed inode. If in that case the first ref would be
  *    overwritten, the overwritten inode gets "orphanized". Later when we
  *    process this overwritten inode, it is restored at a new place by moving
  *    the orphan inode.
  *
  * sctx->send_progress tells this function at which point in time receiving
  * would be.
  */
 static int get_cur_path(struct send_ctx *sctx, u64 ino, u64 gen,
             struct fs_path *dest)
 {
     int ret = 0;
     struct fs_path *name = NULL;
     u64 parent_inode = 0;
     u64 parent_gen = 0;
     int stop = 0;
 
     name = fs_path_alloc();
     if (!name) {
         ret = -ENOMEM;
         goto out;
     }
 
     dest->reversed = 1;
     fs_path_reset(dest);
 
     while (!stop && ino != BTRFS_FIRST_FREE_OBJECTID) {
         struct waiting_dir_move *wdm;
 
         fs_path_reset(name);
 
         if (is_waiting_for_rm(sctx, ino, gen)) {
             ret = gen_unique_name(sctx, ino, gen, name);
             if (ret < 0)
                 goto out;
             ret = fs_path_add_path(dest, name);
             break;
         }
 
         wdm = get_waiting_dir_move(sctx, ino);
         if (wdm && wdm->orphanized) {
             ret = gen_unique_name(sctx, ino, gen, name);
             stop = 1;
         } else if (wdm) {
             ret = get_first_ref(sctx->parent_root, ino,
                         &parent_inode, &parent_gen, name);
         } else {
             ret = __get_cur_name_and_parent(sctx, ino, gen,
                             &parent_inode,
                             &parent_gen, name);
             if (ret)
                 stop = 1;
         }
 
         if (ret < 0)
             goto out;
 
         ret = fs_path_add_path(dest, name);
         if (ret < 0)
             goto out;
 
         ino = parent_inode;
         gen = parent_gen;
     }
 
 out:
     fs_path_free(name);
     if (!ret)
         fs_path_unreverse(dest);
     return ret;
 }
 
 /*
  * Sends a BTRFS_SEND_C_SUBVOL command/item to userspace
  */
 static int send_subvol_begin(struct send_ctx *sctx)
 {
     int ret;
     struct btrfs_root *send_root = sctx->send_root;
     struct btrfs_root *parent_root = sctx->parent_root;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_root_ref *ref;
     struct extent_buffer *leaf;
     char *name = NULL;
     int namelen;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     name = kmalloc(BTRFS_PATH_NAME_MAX, GFP_KERNEL);
     if (!name) {
         btrfs_free_path(path);
         return -ENOMEM;
     }
 
     key.objectid = send_root->root_key.objectid;
     key.type = BTRFS_ROOT_BACKREF_KEY;
     key.offset = 0;
 
     ret = btrfs_search_slot_for_read(send_root->fs_info->tree_root,
                 &key, path, 1, 0);
     if (ret < 0)
         goto out;
     if (ret) {
         ret = -ENOENT;
         goto out;
     }
 
     leaf = path->nodes[0];
     btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
     if (key.type != BTRFS_ROOT_BACKREF_KEY ||
         key.objectid != send_root->root_key.objectid) {
         ret = -ENOENT;
         goto out;
     }
     ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
     namelen = btrfs_root_ref_name_len(leaf, ref);
     read_extent_buffer(leaf, name, (unsigned long)(ref + 1), namelen);
     btrfs_release_path(path);
 
     if (parent_root) {
         ret = begin_cmd(sctx, BTRFS_SEND_C_SNAPSHOT);
         if (ret < 0)
             goto out;
     } else {
         ret = begin_cmd(sctx, BTRFS_SEND_C_SUBVOL);
         if (ret < 0)
             goto out;
     }
 
     TLV_PUT_STRING(sctx, BTRFS_SEND_A_PATH, name, namelen);
 
     if (!btrfs_is_empty_uuid(sctx->send_root->root_item.received_uuid))
         TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
                 sctx->send_root->root_item.received_uuid);
     else
         TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
                 sctx->send_root->root_item.uuid);
 
     TLV_PUT_U64(sctx, BTRFS_SEND_A_CTRANSID,
             btrfs_root_ctransid(&sctx->send_root->root_item));
     if (parent_root) {
         if (!btrfs_is_empty_uuid(parent_root->root_item.received_uuid))
             TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
                      parent_root->root_item.received_uuid);
         else
             TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
                      parent_root->root_item.uuid);
         TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
                 btrfs_root_ctransid(&sctx->parent_root->root_item));
     }
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     btrfs_free_path(path);
     kfree(name);
     return ret;
 }
 
 static int send_truncate(struct send_ctx *sctx, u64 ino, u64 gen, u64 size)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret = 0;
     struct fs_path *p;
 
     btrfs_debug(fs_info, "send_truncate %llu size=%llu", ino, size);
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_TRUNCATE);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, ino, gen, p);
     if (ret < 0)
         goto out;
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, size);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     return ret;
 }
 
 static int send_chmod(struct send_ctx *sctx, u64 ino, u64 gen, u64 mode)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret = 0;
     struct fs_path *p;
 
     btrfs_debug(fs_info, "send_chmod %llu mode=%llu", ino, mode);
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_CHMOD);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, ino, gen, p);
     if (ret < 0)
         goto out;
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode & 07777);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     return ret;
 }
 
 static int send_fileattr(struct send_ctx *sctx, u64 ino, u64 gen, u64 fileattr)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret = 0;
     struct fs_path *p;
 
     if (sctx->proto < 2)
         return 0;
 
     btrfs_debug(fs_info, "send_fileattr %llu fileattr=%llu", ino, fileattr);
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_FILEATTR);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, ino, gen, p);
     if (ret < 0)
         goto out;
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_FILEATTR, fileattr);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     return ret;
 }
 
 static int send_chown(struct send_ctx *sctx, u64 ino, u64 gen, u64 uid, u64 gid)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret = 0;
     struct fs_path *p;
 
     btrfs_debug(fs_info, "send_chown %llu uid=%llu, gid=%llu",
             ino, uid, gid);
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_CHOWN);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, ino, gen, p);
     if (ret < 0)
         goto out;
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_UID, uid);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_GID, gid);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     return ret;
 }
 
 static int send_utimes(struct send_ctx *sctx, u64 ino, u64 gen)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret = 0;
     struct fs_path *p = NULL;
     struct btrfs_inode_item *ii;
     struct btrfs_path *path = NULL;
     struct extent_buffer *eb;
     struct btrfs_key key;
     int slot;
 
     btrfs_debug(fs_info, "send_utimes %llu", ino);
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     path = alloc_path_for_send();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
 
     key.objectid = ino;
     key.type = BTRFS_INODE_ITEM_KEY;
     key.offset = 0;
     ret = btrfs_search_slot(NULL, sctx->send_root, &key, path, 0, 0);
     if (ret > 0)
         ret = -ENOENT;
     if (ret < 0)
         goto out;
 
     eb = path->nodes[0];
     slot = path->slots[0];
     ii = btrfs_item_ptr(eb, slot, struct btrfs_inode_item);
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_UTIMES);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, ino, gen, p);
     if (ret < 0)
         goto out;
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
     TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_ATIME, eb, &ii->atime);
     TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_MTIME, eb, &ii->mtime);
     TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_CTIME, eb, &ii->ctime);
     if (sctx->proto >= 2)
         TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_OTIME, eb, &ii->otime);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * Sends a BTRFS_SEND_C_MKXXX or SYMLINK command to user space. We don't have
  * a valid path yet because we did not process the refs yet. So, the inode
  * is created as orphan.
  */
 static int send_create_inode(struct send_ctx *sctx, u64 ino)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret = 0;
     struct fs_path *p;
     int cmd;
     u64 gen;
     u64 mode;
     u64 rdev;
 
     btrfs_debug(fs_info, "send_create_inode %llu", ino);
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     if (ino != sctx->cur_ino) {
         ret = get_inode_info(sctx->send_root, ino, NULL, &gen, &mode,
                      NULL, NULL, &rdev, NULL);
         if (ret < 0)
             goto out;
     } else {
         gen = sctx->cur_inode_gen;
         mode = sctx->cur_inode_mode;
         rdev = sctx->cur_inode_rdev;
     }
 
     if (S_ISREG(mode)) {
         cmd = BTRFS_SEND_C_MKFILE;
     } else if (S_ISDIR(mode)) {
         cmd = BTRFS_SEND_C_MKDIR;
     } else if (S_ISLNK(mode)) {
         cmd = BTRFS_SEND_C_SYMLINK;
     } else if (S_ISCHR(mode) || S_ISBLK(mode)) {
         cmd = BTRFS_SEND_C_MKNOD;
     } else if (S_ISFIFO(mode)) {
         cmd = BTRFS_SEND_C_MKFIFO;
     } else if (S_ISSOCK(mode)) {
         cmd = BTRFS_SEND_C_MKSOCK;
     } else {
         btrfs_warn(sctx->send_root->fs_info, "unexpected inode type %o",
                 (int)(mode & S_IFMT));
         ret = -EOPNOTSUPP;
         goto out;
     }
 
     ret = begin_cmd(sctx, cmd);
     if (ret < 0)
         goto out;
 
     ret = gen_unique_name(sctx, ino, gen, p);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_INO, ino);
 
     if (S_ISLNK(mode)) {
         fs_path_reset(p);
         ret = read_symlink(sctx->send_root, ino, p);
         if (ret < 0)
             goto out;
         TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, p);
     } else if (S_ISCHR(mode) || S_ISBLK(mode) ||
            S_ISFIFO(mode) || S_ISSOCK(mode)) {
         TLV_PUT_U64(sctx, BTRFS_SEND_A_RDEV, new_encode_dev(rdev));
         TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode);
     }
 
     ret = send_cmd(sctx);
     if (ret < 0)
         goto out;
 
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     return ret;
 }
 
 /*
  * We need some special handling for inodes that get processed before the parent
  * directory got created. See process_recorded_refs for details.
  * This function does the check if we already created the dir out of order.
  */
 static int did_create_dir(struct send_ctx *sctx, u64 dir)
 {
     int ret = 0;
     int iter_ret = 0;
     struct btrfs_path *path = NULL;
     struct btrfs_key key;
     struct btrfs_key found_key;
     struct btrfs_key di_key;
     struct btrfs_dir_item *di;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     key.objectid = dir;
     key.type = BTRFS_DIR_INDEX_KEY;
     key.offset = 0;
 
     btrfs_for_each_slot(sctx->send_root, &key, &found_key, path, iter_ret) {
         struct extent_buffer *eb = path->nodes[0];
 
         if (found_key.objectid != key.objectid ||
             found_key.type != key.type) {
             ret = 0;
             break;
         }
 
         di = btrfs_item_ptr(eb, path->slots[0], struct btrfs_dir_item);
         btrfs_dir_item_key_to_cpu(eb, di, &di_key);
 
         if (di_key.type != BTRFS_ROOT_ITEM_KEY &&
             di_key.objectid < sctx->send_progress) {
             ret = 1;
             break;
         }
     }
     /* Catch error found during iteration */
     if (iter_ret < 0)
         ret = iter_ret;
 
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * Only creates the inode if it is:
  * 1. Not a directory
  * 2. Or a directory which was not created already due to out of order
  *    directories. See did_create_dir and process_recorded_refs for details.
  */
 static int send_create_inode_if_needed(struct send_ctx *sctx)
 {
     int ret;
 
     if (S_ISDIR(sctx->cur_inode_mode)) {
         ret = did_create_dir(sctx, sctx->cur_ino);
         if (ret < 0)
             return ret;
         else if (ret > 0)
             return 0;
     }
 
     return send_create_inode(sctx, sctx->cur_ino);
 }
 
 struct recorded_ref {
     struct list_head list;
     char *name;
     struct fs_path *full_path;
     u64 dir;
     u64 dir_gen;
     int name_len;
     struct rb_node node;
     struct rb_root *root;
 };
 
 static struct recorded_ref *recorded_ref_alloc(void)
 {
     struct recorded_ref *ref;
 
     ref = kzalloc(sizeof(*ref), GFP_KERNEL);
     if (!ref)
         return NULL;
     RB_CLEAR_NODE(&ref->node);
     INIT_LIST_HEAD(&ref->list);
     return ref;
 }
 
 static void recorded_ref_free(struct recorded_ref *ref)
 {
     if (!ref)
         return;
     if (!RB_EMPTY_NODE(&ref->node))
         rb_erase(&ref->node, ref->root);
     list_del(&ref->list);
     fs_path_free(ref->full_path);
     kfree(ref);
 }
 
 static void set_ref_path(struct recorded_ref *ref, struct fs_path *path)
 {
     ref->full_path = path;
     ref->name = (char *)kbasename(ref->full_path->start);
     ref->name_len = ref->full_path->end - ref->name;
 }
 
 static int dup_ref(struct recorded_ref *ref, struct list_head *list)
 {
     struct recorded_ref *new;
 
     new = recorded_ref_alloc();
     if (!new)
         return -ENOMEM;
 
     new->dir = ref->dir;
     new->dir_gen = ref->dir_gen;
     list_add_tail(&new->list, list);
     return 0;
 }
 
 static void __free_recorded_refs(struct list_head *head)
 {
     struct recorded_ref *cur;
 
     while (!list_empty(head)) {
         cur = list_entry(head->next, struct recorded_ref, list);
         recorded_ref_free(cur);
     }
 }
 
 static void free_recorded_refs(struct send_ctx *sctx)
 {
     __free_recorded_refs(&sctx->new_refs);
     __free_recorded_refs(&sctx->deleted_refs);
 }
 
 /*
  * Renames/moves a file/dir to its orphan name. Used when the first
  * ref of an unprocessed inode gets overwritten and for all non empty
  * directories.
  */
 static int orphanize_inode(struct send_ctx *sctx, u64 ino, u64 gen,
               struct fs_path *path)
 {
     int ret;
     struct fs_path *orphan;
 
     orphan = fs_path_alloc();
     if (!orphan)
         return -ENOMEM;
 
     ret = gen_unique_name(sctx, ino, gen, orphan);
     if (ret < 0)
         goto out;
 
     ret = send_rename(sctx, path, orphan);
 
 out:
     fs_path_free(orphan);
     return ret;
 }
 
 static struct orphan_dir_info *add_orphan_dir_info(struct send_ctx *sctx,
                            u64 dir_ino, u64 dir_gen)
 {
     struct rb_node **p = &sctx->orphan_dirs.rb_node;
     struct rb_node *parent = NULL;
     struct orphan_dir_info *entry, *odi;
 
     while (*p) {
         parent = *p;
         entry = rb_entry(parent, struct orphan_dir_info, node);
         if (dir_ino < entry->ino)
             p = &(*p)->rb_left;
         else if (dir_ino > entry->ino)
             p = &(*p)->rb_right;
         else if (dir_gen < entry->gen)
             p = &(*p)->rb_left;
         else if (dir_gen > entry->gen)
             p = &(*p)->rb_right;
         else
             return entry;
     }
 
     odi = kmalloc(sizeof(*odi), GFP_KERNEL);
     if (!odi)
         return ERR_PTR(-ENOMEM);
     odi->ino = dir_ino;
     odi->gen = dir_gen;
     odi->last_dir_index_offset = 0;
 
     rb_link_node(&odi->node, parent, p);
     rb_insert_color(&odi->node, &sctx->orphan_dirs);
     return odi;
 }
 
 static struct orphan_dir_info *get_orphan_dir_info(struct send_ctx *sctx,
                            u64 dir_ino, u64 gen)
 {
     struct rb_node *n = sctx->orphan_dirs.rb_node;
     struct orphan_dir_info *entry;
 
     while (n) {
         entry = rb_entry(n, struct orphan_dir_info, node);
         if (dir_ino < entry->ino)
             n = n->rb_left;
         else if (dir_ino > entry->ino)
             n = n->rb_right;
         else if (gen < entry->gen)
             n = n->rb_left;
         else if (gen > entry->gen)
             n = n->rb_right;
         else
             return entry;
     }
     return NULL;
 }
 
 static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino, u64 gen)
 {
     struct orphan_dir_info *odi = get_orphan_dir_info(sctx, dir_ino, gen);
 
     return odi != NULL;
 }
 
 static void free_orphan_dir_info(struct send_ctx *sctx,
                  struct orphan_dir_info *odi)
 {
     if (!odi)
         return;
     rb_erase(&odi->node, &sctx->orphan_dirs);
     kfree(odi);
 }
 
 /*
  * Returns 1 if a directory can be removed at this point in time.
  * We check this by iterating all dir items and checking if the inode behind
  * the dir item was already processed.
  */
 static int can_rmdir(struct send_ctx *sctx, u64 dir, u64 dir_gen,
              u64 send_progress)
 {
     int ret = 0;
     int iter_ret = 0;
     struct btrfs_root *root = sctx->parent_root;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_key found_key;
     struct btrfs_key loc;
     struct btrfs_dir_item *di;
     struct orphan_dir_info *odi = NULL;
 
     /*
      * Don't try to rmdir the top/root subvolume dir.
      */
     if (dir == BTRFS_FIRST_FREE_OBJECTID)
         return 0;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     key.objectid = dir;
     key.type = BTRFS_DIR_INDEX_KEY;
     key.offset = 0;
 
     odi = get_orphan_dir_info(sctx, dir, dir_gen);
     if (odi)
         key.offset = odi->last_dir_index_offset;
 
     btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
         struct waiting_dir_move *dm;
 
         if (found_key.objectid != key.objectid ||
             found_key.type != key.type)
             break;
 
         di = btrfs_item_ptr(path->nodes[0], path->slots[0],
                 struct btrfs_dir_item);
         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &loc);
 
         dm = get_waiting_dir_move(sctx, loc.objectid);
         if (dm) {
             odi = add_orphan_dir_info(sctx, dir, dir_gen);
             if (IS_ERR(odi)) {
                 ret = PTR_ERR(odi);
                 goto out;
             }
             odi->gen = dir_gen;
             odi->last_dir_index_offset = found_key.offset;
             dm->rmdir_ino = dir;
             dm->rmdir_gen = dir_gen;
             ret = 0;
             goto out;
         }
 
         if (loc.objectid > send_progress) {
             odi = add_orphan_dir_info(sctx, dir, dir_gen);
             if (IS_ERR(odi)) {
                 ret = PTR_ERR(odi);
                 goto out;
             }
             odi->gen = dir_gen;
             odi->last_dir_index_offset = found_key.offset;
             ret = 0;
             goto out;
         }
     }
     if (iter_ret < 0) {
         ret = iter_ret;
         goto out;
     }
     free_orphan_dir_info(sctx, odi);
 
     ret = 1;
 
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int is_waiting_for_move(struct send_ctx *sctx, u64 ino)
 {
     struct waiting_dir_move *entry = get_waiting_dir_move(sctx, ino);
 
     return entry != NULL;
 }
 
 static int add_waiting_dir_move(struct send_ctx *sctx, u64 ino, bool orphanized)
 {
     struct rb_node **p = &sctx->waiting_dir_moves.rb_node;
     struct rb_node *parent = NULL;
     struct waiting_dir_move *entry, *dm;
 
     dm = kmalloc(sizeof(*dm), GFP_KERNEL);
     if (!dm)
         return -ENOMEM;
     dm->ino = ino;
     dm->rmdir_ino = 0;
     dm->rmdir_gen = 0;
     dm->orphanized = orphanized;
 
     while (*p) {
         parent = *p;
         entry = rb_entry(parent, struct waiting_dir_move, node);
         if (ino < entry->ino) {
             p = &(*p)->rb_left;
         } else if (ino > entry->ino) {
             p = &(*p)->rb_right;
         } else {
             kfree(dm);
             return -EEXIST;
         }
     }
 
     rb_link_node(&dm->node, parent, p);
     rb_insert_color(&dm->node, &sctx->waiting_dir_moves);
     return 0;
 }
 
 static struct waiting_dir_move *
 get_waiting_dir_move(struct send_ctx *sctx, u64 ino)
 {
     struct rb_node *n = sctx->waiting_dir_moves.rb_node;
     struct waiting_dir_move *entry;
 
     while (n) {
         entry = rb_entry(n, struct waiting_dir_move, node);
         if (ino < entry->ino)
             n = n->rb_left;
         else if (ino > entry->ino)
             n = n->rb_right;
         else
             return entry;
     }
     return NULL;
 }
 
 static void free_waiting_dir_move(struct send_ctx *sctx,
                   struct waiting_dir_move *dm)
 {
     if (!dm)
         return;
     rb_erase(&dm->node, &sctx->waiting_dir_moves);
     kfree(dm);
 }
 
 static int add_pending_dir_move(struct send_ctx *sctx,
                 u64 ino,
                 u64 ino_gen,
                 u64 parent_ino,
                 struct list_head *new_refs,
                 struct list_head *deleted_refs,
                 const bool is_orphan)
 {
     struct rb_node **p = &sctx->pending_dir_moves.rb_node;
     struct rb_node *parent = NULL;
     struct pending_dir_move *entry = NULL, *pm;
     struct recorded_ref *cur;
     int exists = 0;
     int ret;
 
     pm = kmalloc(sizeof(*pm), GFP_KERNEL);
     if (!pm)
         return -ENOMEM;
     pm->parent_ino = parent_ino;
     pm->ino = ino;
     pm->gen = ino_gen;
     INIT_LIST_HEAD(&pm->list);
     INIT_LIST_HEAD(&pm->update_refs);
     RB_CLEAR_NODE(&pm->node);
 
     while (*p) {
         parent = *p;
         entry = rb_entry(parent, struct pending_dir_move, node);
         if (parent_ino < entry->parent_ino) {
             p = &(*p)->rb_left;
         } else if (parent_ino > entry->parent_ino) {
             p = &(*p)->rb_right;
         } else {
             exists = 1;
             break;
         }
     }
 
     list_for_each_entry(cur, deleted_refs, list) {
         ret = dup_ref(cur, &pm->update_refs);
         if (ret < 0)
             goto out;
     }
     list_for_each_entry(cur, new_refs, list) {
         ret = dup_ref(cur, &pm->update_refs);
         if (ret < 0)
             goto out;
     }
 
     ret = add_waiting_dir_move(sctx, pm->ino, is_orphan);
     if (ret)
         goto out;
 
     if (exists) {
         list_add_tail(&pm->list, &entry->list);
     } else {
         rb_link_node(&pm->node, parent, p);
         rb_insert_color(&pm->node, &sctx->pending_dir_moves);
     }
     ret = 0;
 out:
     if (ret) {
         __free_recorded_refs(&pm->update_refs);
         kfree(pm);
     }
     return ret;
 }
 
 static struct pending_dir_move *get_pending_dir_moves(struct send_ctx *sctx,
                               u64 parent_ino)
 {
     struct rb_node *n = sctx->pending_dir_moves.rb_node;
     struct pending_dir_move *entry;
 
     while (n) {
         entry = rb_entry(n, struct pending_dir_move, node);
         if (parent_ino < entry->parent_ino)
             n = n->rb_left;
         else if (parent_ino > entry->parent_ino)
             n = n->rb_right;
         else
             return entry;
     }
     return NULL;
 }
 
 static int path_loop(struct send_ctx *sctx, struct fs_path *name,
              u64 ino, u64 gen, u64 *ancestor_ino)
 {
     int ret = 0;
     u64 parent_inode = 0;
     u64 parent_gen = 0;
     u64 start_ino = ino;
 
     *ancestor_ino = 0;
     while (ino != BTRFS_FIRST_FREE_OBJECTID) {
         fs_path_reset(name);
 
         if (is_waiting_for_rm(sctx, ino, gen))
             break;
         if (is_waiting_for_move(sctx, ino)) {
             if (*ancestor_ino == 0)
                 *ancestor_ino = ino;
             ret = get_first_ref(sctx->parent_root, ino,
                         &parent_inode, &parent_gen, name);
         } else {
             ret = __get_cur_name_and_parent(sctx, ino, gen,
                             &parent_inode,
                             &parent_gen, name);
             if (ret > 0) {
                 ret = 0;
                 break;
             }
         }
         if (ret < 0)
             break;
         if (parent_inode == start_ino) {
             ret = 1;
             if (*ancestor_ino == 0)
                 *ancestor_ino = ino;
             break;
         }
         ino = parent_inode;
         gen = parent_gen;
     }
     return ret;
 }
 
 static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
 {
     struct fs_path *from_path = NULL;
     struct fs_path *to_path = NULL;
     struct fs_path *name = NULL;
     u64 orig_progress = sctx->send_progress;
     struct recorded_ref *cur;
     u64 parent_ino, parent_gen;
     struct waiting_dir_move *dm = NULL;
     u64 rmdir_ino = 0;
     u64 rmdir_gen;
     u64 ancestor;
     bool is_orphan;
     int ret;
 
     name = fs_path_alloc();
     from_path = fs_path_alloc();
     if (!name || !from_path) {
         ret = -ENOMEM;
         goto out;
     }
 
     dm = get_waiting_dir_move(sctx, pm->ino);
     ASSERT(dm);
     rmdir_ino = dm->rmdir_ino;
     rmdir_gen = dm->rmdir_gen;
     is_orphan = dm->orphanized;
     free_waiting_dir_move(sctx, dm);
 
     if (is_orphan) {
         ret = gen_unique_name(sctx, pm->ino,
                       pm->gen, from_path);
     } else {
         ret = get_first_ref(sctx->parent_root, pm->ino,
                     &parent_ino, &parent_gen, name);
         if (ret < 0)
             goto out;
         ret = get_cur_path(sctx, parent_ino, parent_gen,
                    from_path);
         if (ret < 0)
             goto out;
         ret = fs_path_add_path(from_path, name);
     }
     if (ret < 0)
         goto out;
 
     sctx->send_progress = sctx->cur_ino + 1;
     ret = path_loop(sctx, name, pm->ino, pm->gen, &ancestor);
     if (ret < 0)
         goto out;
     if (ret) {
         LIST_HEAD(deleted_refs);
         ASSERT(ancestor > BTRFS_FIRST_FREE_OBJECTID);
         ret = add_pending_dir_move(sctx, pm->ino, pm->gen, ancestor,
                        &pm->update_refs, &deleted_refs,
                        is_orphan);
         if (ret < 0)
             goto out;
         if (rmdir_ino) {
             dm = get_waiting_dir_move(sctx, pm->ino);
             ASSERT(dm);
             dm->rmdir_ino = rmdir_ino;
             dm->rmdir_gen = rmdir_gen;
         }
         goto out;
     }
     fs_path_reset(name);
     to_path = name;
     name = NULL;
     ret = get_cur_path(sctx, pm->ino, pm->gen, to_path);
     if (ret < 0)
         goto out;
 
     ret = send_rename(sctx, from_path, to_path);
     if (ret < 0)
         goto out;
 
     if (rmdir_ino) {
         struct orphan_dir_info *odi;
         u64 gen;
 
         odi = get_orphan_dir_info(sctx, rmdir_ino, rmdir_gen);
         if (!odi) {
             /* already deleted */
             goto finish;
         }
         gen = odi->gen;
 
         ret = can_rmdir(sctx, rmdir_ino, gen, sctx->cur_ino);
         if (ret < 0)
             goto out;
         if (!ret)
             goto finish;
 
         name = fs_path_alloc();
         if (!name) {
             ret = -ENOMEM;
             goto out;
         }
         ret = get_cur_path(sctx, rmdir_ino, gen, name);
         if (ret < 0)
             goto out;
         ret = send_rmdir(sctx, name);
         if (ret < 0)
             goto out;
     }
 
 finish:
     ret = send_utimes(sctx, pm->ino, pm->gen);
     if (ret < 0)
         goto out;
 
     /*
      * After rename/move, need to update the utimes of both new parent(s)
      * and old parent(s).
      */
     list_for_each_entry(cur, &pm->update_refs, list) {
         /*
          * The parent inode might have been deleted in the send snapshot
          */
         ret = get_inode_info(sctx->send_root, cur->dir, NULL,
                      NULL, NULL, NULL, NULL, NULL, NULL);
         if (ret == -ENOENT) {
             ret = 0;
             continue;
         }
         if (ret < 0)
             goto out;
 
         ret = send_utimes(sctx, cur->dir, cur->dir_gen);
         if (ret < 0)
             goto out;
     }
 
 out:
     fs_path_free(name);
     fs_path_free(from_path);
     fs_path_free(to_path);
     sctx->send_progress = orig_progress;
 
     return ret;
 }
 
 static void free_pending_move(struct send_ctx *sctx, struct pending_dir_move *m)
 {
     if (!list_empty(&m->list))
         list_del(&m->list);
     if (!RB_EMPTY_NODE(&m->node))
         rb_erase(&m->node, &sctx->pending_dir_moves);
     __free_recorded_refs(&m->update_refs);
     kfree(m);
 }
 
 static void tail_append_pending_moves(struct send_ctx *sctx,
                       struct pending_dir_move *moves,
                       struct list_head *stack)
 {
     if (list_empty(&moves->list)) {
         list_add_tail(&moves->list, stack);
     } else {
         LIST_HEAD(list);
         list_splice_init(&moves->list, &list);
         list_add_tail(&moves->list, stack);
         list_splice_tail(&list, stack);
     }
     if (!RB_EMPTY_NODE(&moves->node)) {
         rb_erase(&moves->node, &sctx->pending_dir_moves);
         RB_CLEAR_NODE(&moves->node);
     }
 }
 
 static int apply_children_dir_moves(struct send_ctx *sctx)
 {
     struct pending_dir_move *pm;
     struct list_head stack;
     u64 parent_ino = sctx->cur_ino;
     int ret = 0;
 
     pm = get_pending_dir_moves(sctx, parent_ino);
     if (!pm)
         return 0;
 
     INIT_LIST_HEAD(&stack);
     tail_append_pending_moves(sctx, pm, &stack);
 
     while (!list_empty(&stack)) {
         pm = list_first_entry(&stack, struct pending_dir_move, list);
         parent_ino = pm->ino;
         ret = apply_dir_move(sctx, pm);
         free_pending_move(sctx, pm);
         if (ret)
             goto out;
         pm = get_pending_dir_moves(sctx, parent_ino);
         if (pm)
             tail_append_pending_moves(sctx, pm, &stack);
     }
     return 0;
 
 out:
     while (!list_empty(&stack)) {
         pm = list_first_entry(&stack, struct pending_dir_move, list);
         free_pending_move(sctx, pm);
     }
     return ret;
 }
 
 /*
  * We might need to delay a directory rename even when no ancestor directory
  * (in the send root) with a higher inode number than ours (sctx->cur_ino) was
  * renamed. This happens when we rename a directory to the old name (the name
  * in the parent root) of some other unrelated directory that got its rename
  * delayed due to some ancestor with higher number that got renamed.
  *
  * Example:
  *
  * Parent snapshot:
  * .                                       (ino 256)
  * |---- a/                                (ino 257)
  * |     |---- file                        (ino 260)
  * |
  * |---- b/                                (ino 258)
  * |---- c/                                (ino 259)
  *
  * Send snapshot:
  * .                                       (ino 256)
  * |---- a/                                (ino 258)
  * |---- x/                                (ino 259)
  *       |---- y/                          (ino 257)
  *             |----- file                 (ino 260)
  *
  * Here we can not rename 258 from 'b' to 'a' without the rename of inode 257
  * from 'a' to 'x/y' happening first, which in turn depends on the rename of
  * inode 259 from 'c' to 'x'. So the order of rename commands the send stream
  * must issue is:
  *
  * 1 - rename 259 from 'c' to 'x'
  * 2 - rename 257 from 'a' to 'x/y'
  * 3 - rename 258 from 'b' to 'a'
  *
  * Returns 1 if the rename of sctx->cur_ino needs to be delayed, 0 if it can
  * be done right away and < 0 on error.
  */
 static int wait_for_dest_dir_move(struct send_ctx *sctx,
                   struct recorded_ref *parent_ref,
                   const bool is_orphan)
 {
     struct btrfs_fs_info *fs_info = sctx->parent_root->fs_info;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_key di_key;
     struct btrfs_dir_item *di;
     u64 left_gen;
     u64 right_gen;
     int ret = 0;
     struct waiting_dir_move *wdm;
 
     if (RB_EMPTY_ROOT(&sctx->waiting_dir_moves))
         return 0;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     key.objectid = parent_ref->dir;
     key.type = BTRFS_DIR_ITEM_KEY;
     key.offset = btrfs_name_hash(parent_ref->name, parent_ref->name_len);
 
     ret = btrfs_search_slot(NULL, sctx->parent_root, &key, path, 0, 0);
     if (ret < 0) {
         goto out;
     } else if (ret > 0) {
         ret = 0;
         goto out;
     }
 
     di = btrfs_match_dir_item_name(fs_info, path, parent_ref->name,
                        parent_ref->name_len);
     if (!di) {
         ret = 0;
         goto out;
     }
     /*
      * di_key.objectid has the number of the inode that has a dentry in the
      * parent directory with the same name that sctx->cur_ino is being
      * renamed to. We need to check if that inode is in the send root as
      * well and if it is currently marked as an inode with a pending rename,
      * if it is, we need to delay the rename of sctx->cur_ino as well, so
      * that it happens after that other inode is renamed.
      */
     btrfs_dir_item_key_to_cpu(path->nodes[0], di, &di_key);
     if (di_key.type != BTRFS_INODE_ITEM_KEY) {
         ret = 0;
         goto out;
     }
 
     ret = get_inode_info(sctx->parent_root, di_key.objectid, NULL,
                  &left_gen, NULL, NULL, NULL, NULL, NULL);
     if (ret < 0)
         goto out;
     ret = get_inode_info(sctx->send_root, di_key.objectid, NULL,
                  &right_gen, NULL, NULL, NULL, NULL, NULL);
     if (ret < 0) {
         if (ret == -ENOENT)
             ret = 0;
         goto out;
     }
 
     /* Different inode, no need to delay the rename of sctx->cur_ino */
     if (right_gen != left_gen) {
         ret = 0;
         goto out;
     }
 
     wdm = get_waiting_dir_move(sctx, di_key.objectid);
     if (wdm && !wdm->orphanized) {
         ret = add_pending_dir_move(sctx,
                        sctx->cur_ino,
                        sctx->cur_inode_gen,
                        di_key.objectid,
                        &sctx->new_refs,
                        &sctx->deleted_refs,
                        is_orphan);
         if (!ret)
             ret = 1;
     }
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * Check if inode ino2, or any of its ancestors, is inode ino1.
  * Return 1 if true, 0 if false and < 0 on error.
  */
 static int check_ino_in_path(struct btrfs_root *root,
                  const u64 ino1,
                  const u64 ino1_gen,
                  const u64 ino2,
                  const u64 ino2_gen,
                  struct fs_path *fs_path)
 {
     u64 ino = ino2;
 
     if (ino1 == ino2)
         return ino1_gen == ino2_gen;
 
     while (ino > BTRFS_FIRST_FREE_OBJECTID) {
         u64 parent;
         u64 parent_gen;
         int ret;
 
         fs_path_reset(fs_path);
         ret = get_first_ref(root, ino, &parent, &parent_gen, fs_path);
         if (ret < 0)
             return ret;
         if (parent == ino1)
             return parent_gen == ino1_gen;
         ino = parent;
     }
     return 0;
 }
 
 /*
  * Check if inode ino1 is an ancestor of inode ino2 in the given root for any
  * possible path (in case ino2 is not a directory and has multiple hard links).
  * Return 1 if true, 0 if false and < 0 on error.
  */
 static int is_ancestor(struct btrfs_root *root,
                const u64 ino1,
                const u64 ino1_gen,
                const u64 ino2,
                struct fs_path *fs_path)
 {
     bool free_fs_path = false;
     int ret = 0;
     int iter_ret = 0;
     struct btrfs_path *path = NULL;
     struct btrfs_key key;
 
     if (!fs_path) {
         fs_path = fs_path_alloc();
         if (!fs_path)
             return -ENOMEM;
         free_fs_path = true;
     }
 
     path = alloc_path_for_send();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
 
     key.objectid = ino2;
     key.type = BTRFS_INODE_REF_KEY;
     key.offset = 0;
 
     btrfs_for_each_slot(root, &key, &key, path, iter_ret) {
         struct extent_buffer *leaf = path->nodes[0];
         int slot = path->slots[0];
         u32 cur_offset = 0;
         u32 item_size;
 
         if (key.objectid != ino2)
             break;
         if (key.type != BTRFS_INODE_REF_KEY &&
             key.type != BTRFS_INODE_EXTREF_KEY)
             break;
 
         item_size = btrfs_item_size(leaf, slot);
         while (cur_offset < item_size) {
             u64 parent;
             u64 parent_gen;
 
             if (key.type == BTRFS_INODE_EXTREF_KEY) {
                 unsigned long ptr;
                 struct btrfs_inode_extref *extref;
 
                 ptr = btrfs_item_ptr_offset(leaf, slot);
                 extref = (struct btrfs_inode_extref *)
                     (ptr + cur_offset);
                 parent = btrfs_inode_extref_parent(leaf,
                                    extref);
                 cur_offset += sizeof(*extref);
                 cur_offset += btrfs_inode_extref_name_len(leaf,
                                   extref);
             } else {
                 parent = key.offset;
                 cur_offset = item_size;
             }
 
             ret = get_inode_info(root, parent, NULL, &parent_gen,
                          NULL, NULL, NULL, NULL, NULL);
             if (ret < 0)
                 goto out;
             ret = check_ino_in_path(root, ino1, ino1_gen,
                         parent, parent_gen, fs_path);
             if (ret)
                 goto out;
         }
     }
     ret = 0;
     if (iter_ret < 0)
         ret = iter_ret;
 
 out:
     btrfs_free_path(path);
     if (free_fs_path)
         fs_path_free(fs_path);
     return ret;
 }
 
 static int wait_for_parent_move(struct send_ctx *sctx,
                 struct recorded_ref *parent_ref,
                 const bool is_orphan)
 {
     int ret = 0;
     u64 ino = parent_ref->dir;
     u64 ino_gen = parent_ref->dir_gen;
     u64 parent_ino_before, parent_ino_after;
     struct fs_path *path_before = NULL;
     struct fs_path *path_after = NULL;
     int len1, len2;
 
     path_after = fs_path_alloc();
     path_before = fs_path_alloc();
     if (!path_after || !path_before) {
         ret = -ENOMEM;
         goto out;
     }
 
     /*
      * Our current directory inode may not yet be renamed/moved because some
      * ancestor (immediate or not) has to be renamed/moved first. So find if
      * such ancestor exists and make sure our own rename/move happens after
      * that ancestor is processed to avoid path build infinite loops (done
      * at get_cur_path()).
      */
     while (ino > BTRFS_FIRST_FREE_OBJECTID) {
         u64 parent_ino_after_gen;
 
         if (is_waiting_for_move(sctx, ino)) {
             /*
              * If the current inode is an ancestor of ino in the
              * parent root, we need to delay the rename of the
              * current inode, otherwise don't delayed the rename
              * because we can end up with a circular dependency
              * of renames, resulting in some directories never
              * getting the respective rename operations issued in
              * the send stream or getting into infinite path build
              * loops.
              */
             ret = is_ancestor(sctx->parent_root,
                       sctx->cur_ino, sctx->cur_inode_gen,
                       ino, path_before);
             if (ret)
                 break;
         }
 
         fs_path_reset(path_before);
         fs_path_reset(path_after);
 
         ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
                     &parent_ino_after_gen, path_after);
         if (ret < 0)
             goto out;
         ret = get_first_ref(sctx->parent_root, ino, &parent_ino_before,
                     NULL, path_before);
         if (ret < 0 && ret != -ENOENT) {
             goto out;
         } else if (ret == -ENOENT) {
             ret = 0;
             break;
         }
 
         len1 = fs_path_len(path_before);
         len2 = fs_path_len(path_after);
         if (ino > sctx->cur_ino &&
             (parent_ino_before != parent_ino_after || len1 != len2 ||
              memcmp(path_before->start, path_after->start, len1))) {
             u64 parent_ino_gen;
 
             ret = get_inode_info(sctx->parent_root, ino, NULL,
                          &parent_ino_gen, NULL, NULL, NULL,
                          NULL, NULL);
             if (ret < 0)
                 goto out;
             if (ino_gen == parent_ino_gen) {
                 ret = 1;
                 break;
             }
         }
         ino = parent_ino_after;
         ino_gen = parent_ino_after_gen;
     }
 
 out:
     fs_path_free(path_before);
     fs_path_free(path_after);
 
     if (ret == 1) {
         ret = add_pending_dir_move(sctx,
                        sctx->cur_ino,
                        sctx->cur_inode_gen,
                        ino,
                        &sctx->new_refs,
                        &sctx->deleted_refs,
                        is_orphan);
         if (!ret)
             ret = 1;
     }
 
     return ret;
 }
 
 static int update_ref_path(struct send_ctx *sctx, struct recorded_ref *ref)
 {
     int ret;
     struct fs_path *new_path;
 
     /*
      * Our reference's name member points to its full_path member string, so
      * we use here a new path.
      */
     new_path = fs_path_alloc();
     if (!new_path)
         return -ENOMEM;
 
     ret = get_cur_path(sctx, ref->dir, ref->dir_gen, new_path);
     if (ret < 0) {
         fs_path_free(new_path);
         return ret;
     }
     ret = fs_path_add(new_path, ref->name, ref->name_len);
     if (ret < 0) {
         fs_path_free(new_path);
         return ret;
     }
 
     fs_path_free(ref->full_path);
     set_ref_path(ref, new_path);
 
     return 0;
 }
 
 /*
  * When processing the new references for an inode we may orphanize an existing
  * directory inode because its old name conflicts with one of the new references
  * of the current inode. Later, when processing another new reference of our
  * inode, we might need to orphanize another inode, but the path we have in the
  * reference reflects the pre-orphanization name of the directory we previously
  * orphanized. For example:
  *
  * parent snapshot looks like:
  *
  * .                                     (ino 256)
  * |----- f1                             (ino 257)
  * |----- f2                             (ino 258)
  * |----- d1/                            (ino 259)
  *        |----- d2/                     (ino 260)
  *
  * send snapshot looks like:
  *
  * .                                     (ino 256)
  * |----- d1                             (ino 258)
  * |----- f2/                            (ino 259)
  *        |----- f2_link/                (ino 260)
  *        |       |----- f1              (ino 257)
  *        |
  *        |----- d2                      (ino 258)
  *
  * When processing inode 257 we compute the name for inode 259 as "d1", and we
  * cache it in the name cache. Later when we start processing inode 258, when
  * collecting all its new references we set a full path of "d1/d2" for its new
  * reference with name "d2". When we start processing the new references we
  * start by processing the new reference with name "d1", and this results in
  * orphanizing inode 259, since its old reference causes a conflict. Then we
  * move on the next new reference, with name "d2", and we find out we must
  * orphanize inode 260, as its old reference conflicts with ours - but for the
  * orphanization we use a source path corresponding to the path we stored in the
  * new reference, which is "d1/d2" and not "o259-6-0/d2" - this makes the
  * receiver fail since the path component "d1/" no longer exists, it was renamed
  * to "o259-6-0/" when processing the previous new reference. So in this case we
  * must recompute the path in the new reference and use it for the new
  * orphanization operation.
  */
 static int refresh_ref_path(struct send_ctx *sctx, struct recorded_ref *ref)
 {
     char *name;
     int ret;
 
     name = kmemdup(ref->name, ref->name_len, GFP_KERNEL);
     if (!name)
         return -ENOMEM;
 
     fs_path_reset(ref->full_path);
     ret = get_cur_path(sctx, ref->dir, ref->dir_gen, ref->full_path);
     if (ret < 0)
         goto out;
 
     ret = fs_path_add(ref->full_path, name, ref->name_len);
     if (ret < 0)
         goto out;
 
     /* Update the reference's base name pointer. */
     set_ref_path(ref, ref->full_path);
 out:
     kfree(name);
     return ret;
 }
 
 /*
  * This does all the move/link/unlink/rmdir magic.
  */
 static int process_recorded_refs(struct send_ctx *sctx, int *pending_move)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret = 0;
     struct recorded_ref *cur;
     struct recorded_ref *cur2;
     struct list_head check_dirs;
     struct fs_path *valid_path = NULL;
     u64 ow_inode = 0;
     u64 ow_gen;
     u64 ow_mode;
     int did_overwrite = 0;
     int is_orphan = 0;
     u64 last_dir_ino_rm = 0;
     bool can_rename = true;
     bool orphanized_dir = false;
     bool orphanized_ancestor = false;
 
     btrfs_debug(fs_info, "process_recorded_refs %llu", sctx->cur_ino);
 
     /*
      * This should never happen as the root dir always has the same ref
      * which is always '..'
      */
     BUG_ON(sctx->cur_ino <= BTRFS_FIRST_FREE_OBJECTID);
     INIT_LIST_HEAD(&check_dirs);
 
     valid_path = fs_path_alloc();
     if (!valid_path) {
         ret = -ENOMEM;
         goto out;
     }
 
     /*
      * First, check if the first ref of the current inode was overwritten
      * before. If yes, we know that the current inode was already orphanized
      * and thus use the orphan name. If not, we can use get_cur_path to
      * get the path of the first ref as it would like while receiving at
      * this point in time.
      * New inodes are always orphan at the beginning, so force to use the
      * orphan name in this case.
      * The first ref is stored in valid_path and will be updated if it
      * gets moved around.
      */
     if (!sctx->cur_inode_new) {
         ret = did_overwrite_first_ref(sctx, sctx->cur_ino,
                 sctx->cur_inode_gen);
         if (ret < 0)
             goto out;
         if (ret)
             did_overwrite = 1;
     }
     if (sctx->cur_inode_new || did_overwrite) {
         ret = gen_unique_name(sctx, sctx->cur_ino,
                 sctx->cur_inode_gen, valid_path);
         if (ret < 0)
             goto out;
         is_orphan = 1;
     } else {
         ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen,
                 valid_path);
         if (ret < 0)
             goto out;
     }
 
     /*
      * Before doing any rename and link operations, do a first pass on the
      * new references to orphanize any unprocessed inodes that may have a
      * reference that conflicts with one of the new references of the current
      * inode. This needs to happen first because a new reference may conflict
      * with the old reference of a parent directory, so we must make sure
      * that the path used for link and rename commands don't use an
      * orphanized name when an ancestor was not yet orphanized.
      *
      * Example:
      *
      * Parent snapshot:
      *
      * .                                                      (ino 256)
      * |----- testdir/                                        (ino 259)
      * |          |----- a                                    (ino 257)
      * |
      * |----- b                                               (ino 258)
      *
      * Send snapshot:
      *
      * .                                                      (ino 256)
      * |----- testdir_2/                                      (ino 259)
      * |          |----- a                                    (ino 260)
      * |
      * |----- testdir                                         (ino 257)
      * |----- b                                               (ino 257)
      * |----- b2                                              (ino 258)
      *
      * Processing the new reference for inode 257 with name "b" may happen
      * before processing the new reference with name "testdir". If so, we
      * must make sure that by the time we send a link command to create the
      * hard link "b", inode 259 was already orphanized, since the generated
      * path in "valid_path" already contains the orphanized name for 259.
      * We are processing inode 257, so only later when processing 259 we do
      * the rename operation to change its temporary (orphanized) name to
      * "testdir_2".
      */
     list_for_each_entry(cur, &sctx->new_refs, list) {
         ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
         if (ret < 0)
             goto out;
         if (ret == inode_state_will_create)
             continue;
 
         /*
          * Check if this new ref would overwrite the first ref of another
          * unprocessed inode. If yes, orphanize the overwritten inode.
          * If we find an overwritten ref that is not the first ref,
          * simply unlink it.
          */
         ret = will_overwrite_ref(sctx, cur->dir, cur->dir_gen,
                 cur->name, cur->name_len,
                 &ow_inode, &ow_gen, &ow_mode);
         if (ret < 0)
             goto out;
         if (ret) {
             ret = is_first_ref(sctx->parent_root,
                        ow_inode, cur->dir, cur->name,
                        cur->name_len);
             if (ret < 0)
                 goto out;
             if (ret) {
                 struct name_cache_entry *nce;
                 struct waiting_dir_move *wdm;
 
                 if (orphanized_dir) {
                     ret = refresh_ref_path(sctx, cur);
                     if (ret < 0)
                         goto out;
                 }
 
                 ret = orphanize_inode(sctx, ow_inode, ow_gen,
                         cur->full_path);
                 if (ret < 0)
                     goto out;
                 if (S_ISDIR(ow_mode))
                     orphanized_dir = true;
 
                 /*
                  * If ow_inode has its rename operation delayed
                  * make sure that its orphanized name is used in
                  * the source path when performing its rename
                  * operation.
                  */
                 if (is_waiting_for_move(sctx, ow_inode)) {
                     wdm = get_waiting_dir_move(sctx,
                                    ow_inode);
                     ASSERT(wdm);
                     wdm->orphanized = true;
                 }
 
                 /*
                  * Make sure we clear our orphanized inode's
                  * name from the name cache. This is because the
                  * inode ow_inode might be an ancestor of some
                  * other inode that will be orphanized as well
                  * later and has an inode number greater than
                  * sctx->send_progress. We need to prevent
                  * future name lookups from using the old name
                  * and get instead the orphan name.
                  */
                 nce = name_cache_search(sctx, ow_inode, ow_gen);
                 if (nce) {
                     name_cache_delete(sctx, nce);
                     kfree(nce);
                 }
 
                 /*
                  * ow_inode might currently be an ancestor of
                  * cur_ino, therefore compute valid_path (the
                  * current path of cur_ino) again because it
                  * might contain the pre-orphanization name of
                  * ow_inode, which is no longer valid.
                  */
                 ret = is_ancestor(sctx->parent_root,
                           ow_inode, ow_gen,
                           sctx->cur_ino, NULL);
                 if (ret > 0) {
                     orphanized_ancestor = true;
                     fs_path_reset(valid_path);
                     ret = get_cur_path(sctx, sctx->cur_ino,
                                sctx->cur_inode_gen,
                                valid_path);
                 }
                 if (ret < 0)
                     goto out;
             } else {
                 /*
                  * If we previously orphanized a directory that
                  * collided with a new reference that we already
                  * processed, recompute the current path because
                  * that directory may be part of the path.
                  */
                 if (orphanized_dir) {
                     ret = refresh_ref_path(sctx, cur);
                     if (ret < 0)
                         goto out;
                 }
                 ret = send_unlink(sctx, cur->full_path);
                 if (ret < 0)
                     goto out;
             }
         }
 
     }
 
     list_for_each_entry(cur, &sctx->new_refs, list) {
         /*
          * We may have refs where the parent directory does not exist
          * yet. This happens if the parent directories inum is higher
          * than the current inum. To handle this case, we create the
          * parent directory out of order. But we need to check if this
          * did already happen before due to other refs in the same dir.
          */
         ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
         if (ret < 0)
             goto out;
         if (ret == inode_state_will_create) {
             ret = 0;
             /*
              * First check if any of the current inodes refs did
              * already create the dir.
              */
             list_for_each_entry(cur2, &sctx->new_refs, list) {
                 if (cur == cur2)
                     break;
                 if (cur2->dir == cur->dir) {
                     ret = 1;
                     break;
                 }
             }
 
             /*
              * If that did not happen, check if a previous inode
              * did already create the dir.
              */
             if (!ret)
                 ret = did_create_dir(sctx, cur->dir);
             if (ret < 0)
                 goto out;
             if (!ret) {
                 ret = send_create_inode(sctx, cur->dir);
                 if (ret < 0)
                     goto out;
             }
         }
 
         if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root) {
             ret = wait_for_dest_dir_move(sctx, cur, is_orphan);
             if (ret < 0)
                 goto out;
             if (ret == 1) {
                 can_rename = false;
                 *pending_move = 1;
             }
         }
 
         if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root &&
             can_rename) {
             ret = wait_for_parent_move(sctx, cur, is_orphan);
             if (ret < 0)
                 goto out;
             if (ret == 1) {
                 can_rename = false;
                 *pending_move = 1;
             }
         }
 
         /*
          * link/move the ref to the new place. If we have an orphan
          * inode, move it and update valid_path. If not, link or move
          * it depending on the inode mode.
          */
         if (is_orphan && can_rename) {
             ret = send_rename(sctx, valid_path, cur->full_path);
             if (ret < 0)
                 goto out;
             is_orphan = 0;
             ret = fs_path_copy(valid_path, cur->full_path);
             if (ret < 0)
                 goto out;
         } else if (can_rename) {
             if (S_ISDIR(sctx->cur_inode_mode)) {
                 /*
                  * Dirs can't be linked, so move it. For moved
                  * dirs, we always have one new and one deleted
                  * ref. The deleted ref is ignored later.
                  */
                 ret = send_rename(sctx, valid_path,
                           cur->full_path);
                 if (!ret)
                     ret = fs_path_copy(valid_path,
                                cur->full_path);
                 if (ret < 0)
                     goto out;
             } else {
                 /*
                  * We might have previously orphanized an inode
                  * which is an ancestor of our current inode,
                  * so our reference's full path, which was
                  * computed before any such orphanizations, must
                  * be updated.
                  */
                 if (orphanized_dir) {
                     ret = update_ref_path(sctx, cur);
                     if (ret < 0)
                         goto out;
                 }
                 ret = send_link(sctx, cur->full_path,
                         valid_path);
                 if (ret < 0)
                     goto out;
             }
         }
         ret = dup_ref(cur, &check_dirs);
         if (ret < 0)
             goto out;
     }
 
     if (S_ISDIR(sctx->cur_inode_mode) && sctx->cur_inode_deleted) {
         /*
          * Check if we can already rmdir the directory. If not,
          * orphanize it. For every dir item inside that gets deleted
          * later, we do this check again and rmdir it then if possible.
          * See the use of check_dirs for more details.
          */
         ret = can_rmdir(sctx, sctx->cur_ino, sctx->cur_inode_gen,
                 sctx->cur_ino);
         if (ret < 0)
             goto out;
         if (ret) {
             ret = send_rmdir(sctx, valid_path);
             if (ret < 0)
                 goto out;
         } else if (!is_orphan) {
             ret = orphanize_inode(sctx, sctx->cur_ino,
                     sctx->cur_inode_gen, valid_path);
             if (ret < 0)
                 goto out;
             is_orphan = 1;
         }
 
         list_for_each_entry(cur, &sctx->deleted_refs, list) {
             ret = dup_ref(cur, &check_dirs);
             if (ret < 0)
                 goto out;
         }
     } else if (S_ISDIR(sctx->cur_inode_mode) &&
            !list_empty(&sctx->deleted_refs)) {
         /*
          * We have a moved dir. Add the old parent to check_dirs
          */
         cur = list_entry(sctx->deleted_refs.next, struct recorded_ref,
                 list);
         ret = dup_ref(cur, &check_dirs);
         if (ret < 0)
             goto out;
     } else if (!S_ISDIR(sctx->cur_inode_mode)) {
         /*
          * We have a non dir inode. Go through all deleted refs and
          * unlink them if they were not already overwritten by other
          * inodes.
          */
         list_for_each_entry(cur, &sctx->deleted_refs, list) {
             ret = did_overwrite_ref(sctx, cur->dir, cur->dir_gen,
                     sctx->cur_ino, sctx->cur_inode_gen,
                     cur->name, cur->name_len);
             if (ret < 0)
                 goto out;
             if (!ret) {
                 /*
                  * If we orphanized any ancestor before, we need
                  * to recompute the full path for deleted names,
                  * since any such path was computed before we
                  * processed any references and orphanized any
                  * ancestor inode.
                  */
                 if (orphanized_ancestor) {
                     ret = update_ref_path(sctx, cur);
                     if (ret < 0)
                         goto out;
                 }
                 ret = send_unlink(sctx, cur->full_path);
                 if (ret < 0)
                     goto out;
             }
             ret = dup_ref(cur, &check_dirs);
             if (ret < 0)
                 goto out;
         }
         /*
          * If the inode is still orphan, unlink the orphan. This may
          * happen when a previous inode did overwrite the first ref
          * of this inode and no new refs were added for the current
          * inode. Unlinking does not mean that the inode is deleted in
          * all cases. There may still be links to this inode in other
          * places.
          */
         if (is_orphan) {
             ret = send_unlink(sctx, valid_path);
             if (ret < 0)
                 goto out;
         }
     }
 
     /*
      * We did collect all parent dirs where cur_inode was once located. We
      * now go through all these dirs and check if they are pending for
      * deletion and if it's finally possible to perform the rmdir now.
      * We also update the inode stats of the parent dirs here.
      */
     list_for_each_entry(cur, &check_dirs, list) {
         /*
          * In case we had refs into dirs that were not processed yet,
          * we don't need to do the utime and rmdir logic for these dirs.
          * The dir will be processed later.
          */
         if (cur->dir > sctx->cur_ino)
             continue;
 
         ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
         if (ret < 0)
             goto out;
 
         if (ret == inode_state_did_create ||
             ret == inode_state_no_change) {
             /* TODO delayed utimes */
             ret = send_utimes(sctx, cur->dir, cur->dir_gen);
             if (ret < 0)
                 goto out;
         } else if (ret == inode_state_did_delete &&
                cur->dir != last_dir_ino_rm) {
             ret = can_rmdir(sctx, cur->dir, cur->dir_gen,
                     sctx->cur_ino);
             if (ret < 0)
                 goto out;
             if (ret) {
                 ret = get_cur_path(sctx, cur->dir,
                            cur->dir_gen, valid_path);
                 if (ret < 0)
                     goto out;
                 ret = send_rmdir(sctx, valid_path);
                 if (ret < 0)
                     goto out;
                 last_dir_ino_rm = cur->dir;
             }
         }
     }
 
     ret = 0;
 
 out:
     __free_recorded_refs(&check_dirs);
     free_recorded_refs(sctx);
     fs_path_free(valid_path);
     return ret;
 }
 
 static int rbtree_ref_comp(const void *k, const struct rb_node *node)
 {
     const struct recorded_ref *data = k;
     const struct recorded_ref *ref = rb_entry(node, struct recorded_ref, node);
     int result;
 
     if (data->dir > ref->dir)
         return 1;
     if (data->dir < ref->dir)
         return -1;
     if (data->dir_gen > ref->dir_gen)
         return 1;
     if (data->dir_gen < ref->dir_gen)
         return -1;
     if (data->name_len > ref->name_len)
         return 1;
     if (data->name_len < ref->name_len)
         return -1;
     result = strcmp(data->name, ref->name);
     if (result > 0)
         return 1;
     if (result < 0)
         return -1;
     return 0;
 }
 
 static bool rbtree_ref_less(struct rb_node *node, const struct rb_node *parent)
 {
     const struct recorded_ref *entry = rb_entry(node, struct recorded_ref, node);
 
     return rbtree_ref_comp(entry, parent) < 0;
 }
 
 static int record_ref_in_tree(struct rb_root *root, struct list_head *refs,
                   struct fs_path *name, u64 dir, u64 dir_gen,
                   struct send_ctx *sctx)
 {
     int ret = 0;
     struct fs_path *path = NULL;
     struct recorded_ref *ref = NULL;
 
     path = fs_path_alloc();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
 
     ref = recorded_ref_alloc();
     if (!ref) {
         ret = -ENOMEM;
         goto out;
     }
 
     ret = get_cur_path(sctx, dir, dir_gen, path);
     if (ret < 0)
         goto out;
     ret = fs_path_add_path(path, name);
     if (ret < 0)
         goto out;
 
     ref->dir = dir;
     ref->dir_gen = dir_gen;
     set_ref_path(ref, path);
     list_add_tail(&ref->list, refs);
     rb_add(&ref->node, root, rbtree_ref_less);
     ref->root = root;
 out:
     if (ret) {
         if (path && (!ref || !ref->full_path))
             fs_path_free(path);
         recorded_ref_free(ref);
     }
     return ret;
 }
 
 static int record_new_ref_if_needed(int num, u64 dir, int index,
                     struct fs_path *name, void *ctx)
 {
     int ret = 0;
     struct send_ctx *sctx = ctx;
     struct rb_node *node = NULL;
     struct recorded_ref data;
     struct recorded_ref *ref;
     u64 dir_gen;
 
     ret = get_inode_info(sctx->send_root, dir, NULL, &dir_gen, NULL,
                  NULL, NULL, NULL, NULL);
     if (ret < 0)
         goto out;
 
     data.dir = dir;
     data.dir_gen = dir_gen;
     set_ref_path(&data, name);
     node = rb_find(&data, &sctx->rbtree_deleted_refs, rbtree_ref_comp);
     if (node) {
         ref = rb_entry(node, struct recorded_ref, node);
         recorded_ref_free(ref);
     } else {
         ret = record_ref_in_tree(&sctx->rbtree_new_refs,
                      &sctx->new_refs, name, dir, dir_gen,
                      sctx);
     }
 out:
     return ret;
 }
 
 static int record_deleted_ref_if_needed(int num, u64 dir, int index,
                     struct fs_path *name, void *ctx)
 {
     int ret = 0;
     struct send_ctx *sctx = ctx;
     struct rb_node *node = NULL;
     struct recorded_ref data;
     struct recorded_ref *ref;
     u64 dir_gen;
 
     ret = get_inode_info(sctx->parent_root, dir, NULL, &dir_gen, NULL,
                  NULL, NULL, NULL, NULL);
     if (ret < 0)
         goto out;
 
     data.dir = dir;
     data.dir_gen = dir_gen;
     set_ref_path(&data, name);
     node = rb_find(&data, &sctx->rbtree_new_refs, rbtree_ref_comp);
     if (node) {
         ref = rb_entry(node, struct recorded_ref, node);
         recorded_ref_free(ref);
     } else {
         ret = record_ref_in_tree(&sctx->rbtree_deleted_refs,
                      &sctx->deleted_refs, name, dir,
                      dir_gen, sctx);
     }
 out:
     return ret;
 }
 
 static int record_new_ref(struct send_ctx *sctx)
 {
     int ret;
 
     ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
                 sctx->cmp_key, 0, record_new_ref_if_needed, sctx);
     if (ret < 0)
         goto out;
     ret = 0;
 
 out:
     return ret;
 }
 
 static int record_deleted_ref(struct send_ctx *sctx)
 {
     int ret;
 
     ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
                 sctx->cmp_key, 0, record_deleted_ref_if_needed,
                 sctx);
     if (ret < 0)
         goto out;
     ret = 0;
 
 out:
     return ret;
 }
 
 static int record_changed_ref(struct send_ctx *sctx)
 {
     int ret = 0;
 
     ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
             sctx->cmp_key, 0, record_new_ref_if_needed, sctx);
     if (ret < 0)
         goto out;
     ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
             sctx->cmp_key, 0, record_deleted_ref_if_needed, sctx);
     if (ret < 0)
         goto out;
     ret = 0;
 
 out:
     return ret;
 }
 
 /*
  * Record and process all refs at once. Needed when an inode changes the
  * generation number, which means that it was deleted and recreated.
  */
 static int process_all_refs(struct send_ctx *sctx,
                 enum btrfs_compare_tree_result cmd)
 {
     int ret = 0;
     int iter_ret = 0;
     struct btrfs_root *root;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_key found_key;
     iterate_inode_ref_t cb;
     int pending_move = 0;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     if (cmd == BTRFS_COMPARE_TREE_NEW) {
         root = sctx->send_root;
         cb = record_new_ref_if_needed;
     } else if (cmd == BTRFS_COMPARE_TREE_DELETED) {
         root = sctx->parent_root;
         cb = record_deleted_ref_if_needed;
     } else {
         btrfs_err(sctx->send_root->fs_info,
                 "Wrong command %d in process_all_refs", cmd);
         ret = -EINVAL;
         goto out;
     }
 
     key.objectid = sctx->cmp_key->objectid;
     key.type = BTRFS_INODE_REF_KEY;
     key.offset = 0;
     btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
         if (found_key.objectid != key.objectid ||
             (found_key.type != BTRFS_INODE_REF_KEY &&
              found_key.type != BTRFS_INODE_EXTREF_KEY))
             break;
 
         ret = iterate_inode_ref(root, path, &found_key, 0, cb, sctx);
         if (ret < 0)
             goto out;
     }
     /* Catch error found during iteration */
     if (iter_ret < 0) {
         ret = iter_ret;
         goto out;
     }
     btrfs_release_path(path);
 
     /*
      * We don't actually care about pending_move as we are simply
      * re-creating this inode and will be rename'ing it into place once we
      * rename the parent directory.
      */
     ret = process_recorded_refs(sctx, &pending_move);
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int send_set_xattr(struct send_ctx *sctx,
               struct fs_path *path,
               const char *name, int name_len,
               const char *data, int data_len)
 {
     int ret = 0;
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_SET_XATTR);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
     TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
     TLV_PUT(sctx, BTRFS_SEND_A_XATTR_DATA, data, data_len);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     return ret;
 }
 
 static int send_remove_xattr(struct send_ctx *sctx,
               struct fs_path *path,
               const char *name, int name_len)
 {
     int ret = 0;
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_REMOVE_XATTR);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
     TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     return ret;
 }
 
 static int __process_new_xattr(int num, struct btrfs_key *di_key,
                    const char *name, int name_len, const char *data,
                    int data_len, void *ctx)
 {
     int ret;
     struct send_ctx *sctx = ctx;
     struct fs_path *p;
     struct posix_acl_xattr_header dummy_acl;
 
     /* Capabilities are emitted by finish_inode_if_needed */
     if (!strncmp(name, XATTR_NAME_CAPS, name_len))
         return 0;
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     /*
      * This hack is needed because empty acls are stored as zero byte
      * data in xattrs. Problem with that is, that receiving these zero byte
      * acls will fail later. To fix this, we send a dummy acl list that
      * only contains the version number and no entries.
      */
     if (!strncmp(name, XATTR_NAME_POSIX_ACL_ACCESS, name_len) ||
         !strncmp(name, XATTR_NAME_POSIX_ACL_DEFAULT, name_len)) {
         if (data_len == 0) {
             dummy_acl.a_version =
                     cpu_to_le32(POSIX_ACL_XATTR_VERSION);
             data = (char *)&dummy_acl;
             data_len = sizeof(dummy_acl);
         }
     }
 
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
     if (ret < 0)
         goto out;
 
     ret = send_set_xattr(sctx, p, name, name_len, data, data_len);
 
 out:
     fs_path_free(p);
     return ret;
 }
 
 static int __process_deleted_xattr(int num, struct btrfs_key *di_key,
                    const char *name, int name_len,
                    const char *data, int data_len, void *ctx)
 {
     int ret;
     struct send_ctx *sctx = ctx;
     struct fs_path *p;
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
     if (ret < 0)
         goto out;
 
     ret = send_remove_xattr(sctx, p, name, name_len);
 
 out:
     fs_path_free(p);
     return ret;
 }
 
 static int process_new_xattr(struct send_ctx *sctx)
 {
     int ret = 0;
 
     ret = iterate_dir_item(sctx->send_root, sctx->left_path,
                    __process_new_xattr, sctx);
 
     return ret;
 }
 
 static int process_deleted_xattr(struct send_ctx *sctx)
 {
     return iterate_dir_item(sctx->parent_root, sctx->right_path,
                 __process_deleted_xattr, sctx);
 }
 
 struct find_xattr_ctx {
     const char *name;
     int name_len;
     int found_idx;
     char *found_data;
     int found_data_len;
 };
 
 static int __find_xattr(int num, struct btrfs_key *di_key, const char *name,
             int name_len, const char *data, int data_len, void *vctx)
 {
     struct find_xattr_ctx *ctx = vctx;
 
     if (name_len == ctx->name_len &&
         strncmp(name, ctx->name, name_len) == 0) {
         ctx->found_idx = num;
         ctx->found_data_len = data_len;
         ctx->found_data = kmemdup(data, data_len, GFP_KERNEL);
         if (!ctx->found_data)
             return -ENOMEM;
         return 1;
     }
     return 0;
 }
 
 static int find_xattr(struct btrfs_root *root,
               struct btrfs_path *path,
               struct btrfs_key *key,
               const char *name, int name_len,
               char **data, int *data_len)
 {
     int ret;
     struct find_xattr_ctx ctx;
 
     ctx.name = name;
     ctx.name_len = name_len;
     ctx.found_idx = -1;
     ctx.found_data = NULL;
     ctx.found_data_len = 0;
 
     ret = iterate_dir_item(root, path, __find_xattr, &ctx);
     if (ret < 0)
         return ret;
 
     if (ctx.found_idx == -1)
         return -ENOENT;
     if (data) {
         *data = ctx.found_data;
         *data_len = ctx.found_data_len;
     } else {
         kfree(ctx.found_data);
     }
     return ctx.found_idx;
 }
 
 
 static int __process_changed_new_xattr(int num, struct btrfs_key *di_key,
                        const char *name, int name_len,
                        const char *data, int data_len,
                        void *ctx)
 {
     int ret;
     struct send_ctx *sctx = ctx;
     char *found_data = NULL;
     int found_data_len  = 0;
 
     ret = find_xattr(sctx->parent_root, sctx->right_path,
              sctx->cmp_key, name, name_len, &found_data,
              &found_data_len);
     if (ret == -ENOENT) {
         ret = __process_new_xattr(num, di_key, name, name_len, data,
                       data_len, ctx);
     } else if (ret >= 0) {
         if (data_len != found_data_len ||
             memcmp(data, found_data, data_len)) {
             ret = __process_new_xattr(num, di_key, name, name_len,
                           data, data_len, ctx);
         } else {
             ret = 0;
         }
     }
 
     kfree(found_data);
     return ret;
 }
 
 static int __process_changed_deleted_xattr(int num, struct btrfs_key *di_key,
                        const char *name, int name_len,
                        const char *data, int data_len,
                        void *ctx)
 {
     int ret;
     struct send_ctx *sctx = ctx;
 
     ret = find_xattr(sctx->send_root, sctx->left_path, sctx->cmp_key,
              name, name_len, NULL, NULL);
     if (ret == -ENOENT)
         ret = __process_deleted_xattr(num, di_key, name, name_len, data,
                           data_len, ctx);
     else if (ret >= 0)
         ret = 0;
 
     return ret;
 }
 
 static int process_changed_xattr(struct send_ctx *sctx)
 {
     int ret = 0;
 
     ret = iterate_dir_item(sctx->send_root, sctx->left_path,
             __process_changed_new_xattr, sctx);
     if (ret < 0)
         goto out;
     ret = iterate_dir_item(sctx->parent_root, sctx->right_path,
             __process_changed_deleted_xattr, sctx);
 
 out:
     return ret;
 }
 
 static int process_all_new_xattrs(struct send_ctx *sctx)
 {
     int ret = 0;
     int iter_ret = 0;
     struct btrfs_root *root;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_key found_key;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     root = sctx->send_root;
 
     key.objectid = sctx->cmp_key->objectid;
     key.type = BTRFS_XATTR_ITEM_KEY;
     key.offset = 0;
     btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
         if (found_key.objectid != key.objectid ||
             found_key.type != key.type) {
             ret = 0;
             break;
         }
 
         ret = iterate_dir_item(root, path, __process_new_xattr, sctx);
         if (ret < 0)
             break;
     }
     /* Catch error found during iteration */
     if (iter_ret < 0)
         ret = iter_ret;
 
     btrfs_free_path(path);
     return ret;
 }
 
 static inline u64 max_send_read_size(const struct send_ctx *sctx)
 {
     return sctx->send_max_size - SZ_16K;
 }
 
 static int put_data_header(struct send_ctx *sctx, u32 len)
 {
     if (WARN_ON_ONCE(sctx->put_data))
         return -EINVAL;
     sctx->put_data = true;
     if (sctx->proto >= 2) {
         /*
          * Since v2, the data attribute header doesn't include a length,
          * it is implicitly to the end of the command.
          */
         if (sctx->send_max_size - sctx->send_size < sizeof(__le16) + len)
             return -EOVERFLOW;
         put_unaligned_le16(BTRFS_SEND_A_DATA, sctx->send_buf + sctx->send_size);
         sctx->send_size += sizeof(__le16);
     } else {
         struct btrfs_tlv_header *hdr;
 
         if (sctx->send_max_size - sctx->send_size < sizeof(*hdr) + len)
             return -EOVERFLOW;
         hdr = (struct btrfs_tlv_header *)(sctx->send_buf + sctx->send_size);
         put_unaligned_le16(BTRFS_SEND_A_DATA, &hdr->tlv_type);
         put_unaligned_le16(len, &hdr->tlv_len);
         sctx->send_size += sizeof(*hdr);
     }
     return 0;
 }
 
 static int put_file_data(struct send_ctx *sctx, u64 offset, u32 len)
 {
     struct btrfs_root *root = sctx->send_root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct page *page;
     pgoff_t index = offset >> PAGE_SHIFT;
     pgoff_t last_index;
     unsigned pg_offset = offset_in_page(offset);
     int ret;
 
     ret = put_data_header(sctx, len);
     if (ret)
         return ret;
 
     last_index = (offset + len - 1) >> PAGE_SHIFT;
 
     while (index <= last_index) {
         unsigned cur_len = min_t(unsigned, len,
                      PAGE_SIZE - pg_offset);
 
         page = find_lock_page(sctx->cur_inode->i_mapping, index);
         if (!page) {
             page_cache_sync_readahead(sctx->cur_inode->i_mapping,
                           &sctx->ra, NULL, index,
                           last_index + 1 - index);
 
             page = find_or_create_page(sctx->cur_inode->i_mapping,
                            index, GFP_KERNEL);
             if (!page) {
                 ret = -ENOMEM;
                 break;
             }
         }
 
         if (PageReadahead(page))
             page_cache_async_readahead(sctx->cur_inode->i_mapping,
                            &sctx->ra, NULL, page_folio(page),
                            index, last_index + 1 - index);
 
         if (!PageUptodate(page)) {
             btrfs_read_folio(NULL, page_folio(page));
             lock_page(page);
             if (!PageUptodate(page)) {
                 unlock_page(page);
                 btrfs_err(fs_info,
             "send: IO error at offset %llu for inode %llu root %llu",
                     page_offset(page), sctx->cur_ino,
                     sctx->send_root->root_key.objectid);
                 put_page(page);
                 ret = -EIO;
                 break;
             }
         }
 
         memcpy_from_page(sctx->send_buf + sctx->send_size, page,
                  pg_offset, cur_len);
         unlock_page(page);
         put_page(page);
         index++;
         pg_offset = 0;
         len -= cur_len;
         sctx->send_size += cur_len;
     }
 
     return ret;
 }
 
 /*
  * Read some bytes from the current inode/file and send a write command to
  * user space.
  */
 static int send_write(struct send_ctx *sctx, u64 offset, u32 len)
 {
     struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
     int ret = 0;
     struct fs_path *p;
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     btrfs_debug(fs_info, "send_write offset=%llu, len=%d", offset, len);
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
     ret = put_file_data(sctx, offset, len);
     if (ret < 0)
         goto out;
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     return ret;
 }
 
 /*
  * Send a clone command to user space.
  */
 static int send_clone(struct send_ctx *sctx,
               u64 offset, u32 len,
               struct clone_root *clone_root)
 {
     int ret = 0;
     struct fs_path *p;
     u64 gen;
 
     btrfs_debug(sctx->send_root->fs_info,
             "send_clone offset=%llu, len=%d, clone_root=%llu, clone_inode=%llu, clone_offset=%llu",
             offset, len, clone_root->root->root_key.objectid,
             clone_root->ino, clone_root->offset);
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_CLONE);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
     if (ret < 0)
         goto out;
 
     TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_LEN, len);
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
 
     if (clone_root->root == sctx->send_root) {
         ret = get_inode_info(sctx->send_root, clone_root->ino, NULL,
                 &gen, NULL, NULL, NULL, NULL, NULL);
         if (ret < 0)
             goto out;
         ret = get_cur_path(sctx, clone_root->ino, gen, p);
     } else {
         ret = get_inode_path(clone_root->root, clone_root->ino, p);
     }
     if (ret < 0)
         goto out;
 
     /*
      * If the parent we're using has a received_uuid set then use that as
      * our clone source as that is what we will look for when doing a
      * receive.
      *
      * This covers the case that we create a snapshot off of a received
      * subvolume and then use that as the parent and try to receive on a
      * different host.
      */
     if (!btrfs_is_empty_uuid(clone_root->root->root_item.received_uuid))
         TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
                  clone_root->root->root_item.received_uuid);
     else
         TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
                  clone_root->root->root_item.uuid);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
             btrfs_root_ctransid(&clone_root->root->root_item));
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_CLONE_PATH, p);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_OFFSET,
             clone_root->offset);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     return ret;
 }
 
 /*
  * Send an update extent command to user space.
  */
 static int send_update_extent(struct send_ctx *sctx,
                   u64 offset, u32 len)
 {
     int ret = 0;
     struct fs_path *p;
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_UPDATE_EXTENT);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
     if (ret < 0)
         goto out;
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, len);
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(p);
     return ret;
 }
 
 static int send_hole(struct send_ctx *sctx, u64 end)
 {
     struct fs_path *p = NULL;
     u64 read_size = max_send_read_size(sctx);
     u64 offset = sctx->cur_inode_last_extent;
     int ret = 0;
 
     /*
      * A hole that starts at EOF or beyond it. Since we do not yet support
      * fallocate (for extent preallocation and hole punching), sending a
      * write of zeroes starting at EOF or beyond would later require issuing
      * a truncate operation which would undo the write and achieve nothing.
      */
     if (offset >= sctx->cur_inode_size)
         return 0;
 
     /*
      * Don't go beyond the inode's i_size due to prealloc extents that start
      * after the i_size.
      */
     end = min_t(u64, end, sctx->cur_inode_size);
 
     if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
         return send_update_extent(sctx, offset, end - offset);
 
     p = fs_path_alloc();
     if (!p)
         return -ENOMEM;
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
     if (ret < 0)
         goto tlv_put_failure;
     while (offset < end) {
         u64 len = min(end - offset, read_size);
 
         ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
         if (ret < 0)
             break;
         TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
         TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
         ret = put_data_header(sctx, len);
         if (ret < 0)
             break;
         memset(sctx->send_buf + sctx->send_size, 0, len);
         sctx->send_size += len;
         ret = send_cmd(sctx);
         if (ret < 0)
             break;
         offset += len;
     }
     sctx->cur_inode_next_write_offset = offset;
 tlv_put_failure:
     fs_path_free(p);
     return ret;
 }
 
 static int send_encoded_inline_extent(struct send_ctx *sctx,
                       struct btrfs_path *path, u64 offset,
                       u64 len)
 {
     struct btrfs_root *root = sctx->send_root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct inode *inode;
     struct fs_path *fspath;
     struct extent_buffer *leaf = path->nodes[0];
     struct btrfs_key key;
     struct btrfs_file_extent_item *ei;
     u64 ram_bytes;
     size_t inline_size;
     int ret;
 
     inode = btrfs_iget(fs_info->sb, sctx->cur_ino, root);
     if (IS_ERR(inode))
         return PTR_ERR(inode);
 
     fspath = fs_path_alloc();
     if (!fspath) {
         ret = -ENOMEM;
         goto out;
     }
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_ENCODED_WRITE);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, fspath);
     if (ret < 0)
         goto out;
 
     btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
     ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
     ram_bytes = btrfs_file_extent_ram_bytes(leaf, ei);
     inline_size = btrfs_file_extent_inline_item_len(leaf, path->slots[0]);
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, fspath);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_FILE_LEN,
             min(key.offset + ram_bytes - offset, len));
     TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_LEN, ram_bytes);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_OFFSET, offset - key.offset);
     ret = btrfs_encoded_io_compression_from_extent(fs_info,
                 btrfs_file_extent_compression(leaf, ei));
     if (ret < 0)
         goto out;
     TLV_PUT_U32(sctx, BTRFS_SEND_A_COMPRESSION, ret);
 
     ret = put_data_header(sctx, inline_size);
     if (ret < 0)
         goto out;
     read_extent_buffer(leaf, sctx->send_buf + sctx->send_size,
                btrfs_file_extent_inline_start(ei), inline_size);
     sctx->send_size += inline_size;
 
     ret = send_cmd(sctx);
 
 tlv_put_failure:
 out:
     fs_path_free(fspath);
     iput(inode);
     return ret;
 }
 
 static int send_encoded_extent(struct send_ctx *sctx, struct btrfs_path *path,
                    u64 offset, u64 len)
 {
     struct btrfs_root *root = sctx->send_root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct inode *inode;
     struct fs_path *fspath;
     struct extent_buffer *leaf = path->nodes[0];
     struct btrfs_key key;
     struct btrfs_file_extent_item *ei;
     u64 disk_bytenr, disk_num_bytes;
     u32 data_offset;
     struct btrfs_cmd_header *hdr;
     u32 crc;
     int ret;
 
     inode = btrfs_iget(fs_info->sb, sctx->cur_ino, root);
     if (IS_ERR(inode))
         return PTR_ERR(inode);
 
     fspath = fs_path_alloc();
     if (!fspath) {
         ret = -ENOMEM;
         goto out;
     }
 
     ret = begin_cmd(sctx, BTRFS_SEND_C_ENCODED_WRITE);
     if (ret < 0)
         goto out;
 
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, fspath);
     if (ret < 0)
         goto out;
 
     btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
     ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
     disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei);
     disk_num_bytes = btrfs_file_extent_disk_num_bytes(leaf, ei);
 
     TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, fspath);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
     TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_FILE_LEN,
             min(key.offset + btrfs_file_extent_num_bytes(leaf, ei) - offset,
             len));
     TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_LEN,
             btrfs_file_extent_ram_bytes(leaf, ei));
     TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_OFFSET,
             offset - key.offset + btrfs_file_extent_offset(leaf, ei));
     ret = btrfs_encoded_io_compression_from_extent(fs_info,
                 btrfs_file_extent_compression(leaf, ei));
     if (ret < 0)
         goto out;
     TLV_PUT_U32(sctx, BTRFS_SEND_A_COMPRESSION, ret);
     TLV_PUT_U32(sctx, BTRFS_SEND_A_ENCRYPTION, 0);
 
     ret = put_data_header(sctx, disk_num_bytes);
     if (ret < 0)
         goto out;
 
     /*
      * We want to do I/O directly into the send buffer, so get the next page
      * boundary in the send buffer. This means that there may be a gap
      * between the beginning of the command and the file data.
      */
     data_offset = ALIGN(sctx->send_size, PAGE_SIZE);
     if (data_offset > sctx->send_max_size ||
         sctx->send_max_size - data_offset < disk_num_bytes) {
         ret = -EOVERFLOW;
         goto out;
     }
 
     /*
      * Note that send_buf is a mapping of send_buf_pages, so this is really
      * reading into send_buf.
      */
     ret = btrfs_encoded_read_regular_fill_pages(BTRFS_I(inode), offset,
                             disk_bytenr, disk_num_bytes,
                             sctx->send_buf_pages +
                             (data_offset >> PAGE_SHIFT));
     if (ret)
         goto out;
 
     hdr = (struct btrfs_cmd_header *)sctx->send_buf;
     hdr->len = cpu_to_le32(sctx->send_size + disk_num_bytes - sizeof(*hdr));
     hdr->crc = 0;
     crc = btrfs_crc32c(0, sctx->send_buf, sctx->send_size);
     crc = btrfs_crc32c(crc, sctx->send_buf + data_offset, disk_num_bytes);
     hdr->crc = cpu_to_le32(crc);
 
     ret = write_buf(sctx->send_filp, sctx->send_buf, sctx->send_size,
             &sctx->send_off);
     if (!ret) {
         ret = write_buf(sctx->send_filp, sctx->send_buf + data_offset,
                 disk_num_bytes, &sctx->send_off);
     }
     sctx->send_size = 0;
     sctx->put_data = false;
 
 tlv_put_failure:
 out:
     fs_path_free(fspath);
     iput(inode);
     return ret;
 }
 
 static int send_extent_data(struct send_ctx *sctx, struct btrfs_path *path,
                 const u64 offset, const u64 len)
 {
     const u64 end = offset + len;
     struct extent_buffer *leaf = path->nodes[0];
     struct btrfs_file_extent_item *ei;
     u64 read_size = max_send_read_size(sctx);
     u64 sent = 0;
 
     if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
         return send_update_extent(sctx, offset, len);
 
     ei = btrfs_item_ptr(leaf, path->slots[0],
                 struct btrfs_file_extent_item);
     if ((sctx->flags & BTRFS_SEND_FLAG_COMPRESSED) &&
         btrfs_file_extent_compression(leaf, ei) != BTRFS_COMPRESS_NONE) {
         bool is_inline = (btrfs_file_extent_type(leaf, ei) ==
                   BTRFS_FILE_EXTENT_INLINE);
 
         /*
          * Send the compressed extent unless the compressed data is
          * larger than the decompressed data. This can happen if we're
          * not sending the entire extent, either because it has been
          * partially overwritten/truncated or because this is a part of
          * the extent that we couldn't clone in clone_range().
          */
         if (is_inline &&
             btrfs_file_extent_inline_item_len(leaf,
                               path->slots[0]) <= len) {
             return send_encoded_inline_extent(sctx, path, offset,
                               len);
         } else if (!is_inline &&
                btrfs_file_extent_disk_num_bytes(leaf, ei) <= len) {
             return send_encoded_extent(sctx, path, offset, len);
         }
     }
 
     if (sctx->cur_inode == NULL) {
         struct btrfs_root *root = sctx->send_root;
 
         sctx->cur_inode = btrfs_iget(root->fs_info->sb, sctx->cur_ino, root);
         if (IS_ERR(sctx->cur_inode)) {
             int err = PTR_ERR(sctx->cur_inode);
 
             sctx->cur_inode = NULL;
             return err;
         }
         memset(&sctx->ra, 0, sizeof(struct file_ra_state));
         file_ra_state_init(&sctx->ra, sctx->cur_inode->i_mapping);
 
         /*
          * It's very likely there are no pages from this inode in the page
          * cache, so after reading extents and sending their data, we clean
          * the page cache to avoid trashing the page cache (adding pressure
          * to the page cache and forcing eviction of other data more useful
          * for applications).
          *
          * We decide if we should clean the page cache simply by checking
          * if the inode's mapping nrpages is 0 when we first open it, and
          * not by using something like filemap_range_has_page() before
          * reading an extent because when we ask the readahead code to
          * read a given file range, it may (and almost always does) read
          * pages from beyond that range (see the documentation for
          * page_cache_sync_readahead()), so it would not be reliable,
          * because after reading the first extent future calls to
          * filemap_range_has_page() would return true because the readahead
          * on the previous extent resulted in reading pages of the current
          * extent as well.
          */
         sctx->clean_page_cache = (sctx->cur_inode->i_mapping->nrpages == 0);
         sctx->page_cache_clear_start = round_down(offset, PAGE_SIZE);
     }
 
     while (sent < len) {
         u64 size = min(len - sent, read_size);
         int ret;
 
         ret = send_write(sctx, offset + sent, size);
         if (ret < 0)
             return ret;
         sent += size;
     }
 
     if (sctx->clean_page_cache && IS_ALIGNED(end, PAGE_SIZE)) {
         /*
          * Always operate only on ranges that are a multiple of the page
          * size. This is not only to prevent zeroing parts of a page in
          * the case of subpage sector size, but also to guarantee we evict
          * pages, as passing a range that is smaller than page size does
          * not evict the respective page (only zeroes part of its content).
          *
          * Always start from the end offset of the last range cleared.
          * This is because the readahead code may (and very often does)
          * reads pages beyond the range we request for readahead. So if
          * we have an extent layout like this:
          *
          *            [ extent A ] [ extent B ] [ extent C ]
          *
          * When we ask page_cache_sync_readahead() to read extent A, it
          * may also trigger reads for pages of extent B. If we are doing
          * an incremental send and extent B has not changed between the
          * parent and send snapshots, some or all of its pages may end
          * up being read and placed in the page cache. So when truncating
          * the page cache we always start from the end offset of the
          * previously processed extent up to the end of the current
          * extent.
          */
         truncate_inode_pages_range(&sctx->cur_inode->i_data,
                        sctx->page_cache_clear_start,
                        end - 1);
         sctx->page_cache_clear_start = end;
     }
 
     return 0;
 }
 
 /*
  * Search for a capability xattr related to sctx->cur_ino. If the capability is
  * found, call send_set_xattr function to emit it.
  *
  * Return 0 if there isn't a capability, or when the capability was emitted
  * successfully, or < 0 if an error occurred.
  */
 static int send_capabilities(struct send_ctx *sctx)
 {
     struct fs_path *fspath = NULL;
     struct btrfs_path *path;
     struct btrfs_dir_item *di;
     struct extent_buffer *leaf;
     unsigned long data_ptr;
     char *buf = NULL;
     int buf_len;
     int ret = 0;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     di = btrfs_lookup_xattr(NULL, sctx->send_root, path, sctx->cur_ino,
                 XATTR_NAME_CAPS, strlen(XATTR_NAME_CAPS), 0);
     if (!di) {
         /* There is no xattr for this inode */
         goto out;
     } else if (IS_ERR(di)) {
         ret = PTR_ERR(di);
         goto out;
     }
 
     leaf = path->nodes[0];
     buf_len = btrfs_dir_data_len(leaf, di);
 
     fspath = fs_path_alloc();
     buf = kmalloc(buf_len, GFP_KERNEL);
     if (!fspath || !buf) {
         ret = -ENOMEM;
         goto out;
     }
 
     ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, fspath);
     if (ret < 0)
         goto out;
 
     data_ptr = (unsigned long)(di + 1) + btrfs_dir_name_len(leaf, di);
     read_extent_buffer(leaf, buf, data_ptr, buf_len);
 
     ret = send_set_xattr(sctx, fspath, XATTR_NAME_CAPS,
             strlen(XATTR_NAME_CAPS), buf, buf_len);
 out:
     kfree(buf);
     fs_path_free(fspath);
     btrfs_free_path(path);
     return ret;
 }
 
 static int clone_range(struct send_ctx *sctx, struct btrfs_path *dst_path,
                struct clone_root *clone_root, const u64 disk_byte,
                u64 data_offset, u64 offset, u64 len)
 {
     struct btrfs_path *path;
     struct btrfs_key key;
     int ret;
     u64 clone_src_i_size = 0;
 
     /*
      * Prevent cloning from a zero offset with a length matching the sector
      * size because in some scenarios this will make the receiver fail.
      *
      * For example, if in the source filesystem the extent at offset 0
      * has a length of sectorsize and it was written using direct IO, then
      * it can never be an inline extent (even if compression is enabled).
      * Then this extent can be cloned in the original filesystem to a non
      * zero file offset, but it may not be possible to clone in the
      * destination filesystem because it can be inlined due to compression
      * on the destination filesystem (as the receiver's write operations are
      * always done using buffered IO). The same happens when the original
      * filesystem does not have compression enabled but the destination
      * filesystem has.
      */
     if (clone_root->offset == 0 &&
         len == sctx->send_root->fs_info->sectorsize)
         return send_extent_data(sctx, dst_path, offset, len);
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     /*
      * There are inodes that have extents that lie behind its i_size. Don't
      * accept clones from these extents.
      */
     ret = __get_inode_info(clone_root->root, path, clone_root->ino,
                    &clone_src_i_size, NULL, NULL, NULL, NULL, NULL,
                    NULL);
     btrfs_release_path(path);
     if (ret < 0)
         goto out;
 
     /*
      * We can't send a clone operation for the entire range if we find
      * extent items in the respective range in the source file that
      * refer to different extents or if we find holes.
      * So check for that and do a mix of clone and regular write/copy
      * operations if needed.
      *
      * Example:
      *
      * mkfs.btrfs -f /dev/sda
      * mount /dev/sda /mnt
      * xfs_io -f -c "pwrite -S 0xaa 0K 100K" /mnt/foo
      * cp --reflink=always /mnt/foo /mnt/bar
      * xfs_io -c "pwrite -S 0xbb 50K 50K" /mnt/foo
      * btrfs subvolume snapshot -r /mnt /mnt/snap
      *
      * If when we send the snapshot and we are processing file bar (which
      * has a higher inode number than foo) we blindly send a clone operation
      * for the [0, 100K[ range from foo to bar, the receiver ends up getting
      * a file bar that matches the content of file foo - iow, doesn't match
      * the content from bar in the original filesystem.
      */
     key.objectid = clone_root->ino;
     key.type = BTRFS_EXTENT_DATA_KEY;
     key.offset = clone_root->offset;
     ret = btrfs_search_slot(NULL, clone_root->root, &key, path, 0, 0);
     if (ret < 0)
         goto out;
     if (ret > 0 && path->slots[0] > 0) {
         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1);
         if (key.objectid == clone_root->ino &&
             key.type == BTRFS_EXTENT_DATA_KEY)
             path->slots[0]--;
     }
 
     while (true) {
         struct extent_buffer *leaf = path->nodes[0];
         int slot = path->slots[0];
         struct btrfs_file_extent_item *ei;
         u8 type;
         u64 ext_len;
         u64 clone_len;
         u64 clone_data_offset;
 
         if (slot >= btrfs_header_nritems(leaf)) {
             ret = btrfs_next_leaf(clone_root->root, path);
             if (ret < 0)
                 goto out;
             else if (ret > 0)
                 break;
             continue;
         }
 
         btrfs_item_key_to_cpu(leaf, &key, slot);
 
         /*
          * We might have an implicit trailing hole (NO_HOLES feature
          * enabled). We deal with it after leaving this loop.
          */
         if (key.objectid != clone_root->ino ||
             key.type != BTRFS_EXTENT_DATA_KEY)
             break;
 
         ei = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
         type = btrfs_file_extent_type(leaf, ei);
         if (type == BTRFS_FILE_EXTENT_INLINE) {
             ext_len = btrfs_file_extent_ram_bytes(leaf, ei);
             ext_len = PAGE_ALIGN(ext_len);
         } else {
             ext_len = btrfs_file_extent_num_bytes(leaf, ei);
         }
 
         if (key.offset + ext_len <= clone_root->offset)
             goto next;
 
         if (key.offset > clone_root->offset) {
             /* Implicit hole, NO_HOLES feature enabled. */
             u64 hole_len = key.offset - clone_root->offset;
 
             if (hole_len > len)
                 hole_len = len;
             ret = send_extent_data(sctx, dst_path, offset,
                            hole_len);
             if (ret < 0)
                 goto out;
 
             len -= hole_len;
             if (len == 0)
                 break;
             offset += hole_len;
             clone_root->offset += hole_len;
             data_offset += hole_len;
         }
 
         if (key.offset >= clone_root->offset + len)
             break;
 
         if (key.offset >= clone_src_i_size)
             break;
 
         if (key.offset + ext_len > clone_src_i_size)
             ext_len = clone_src_i_size - key.offset;
 
         clone_data_offset = btrfs_file_extent_offset(leaf, ei);
         if (btrfs_file_extent_disk_bytenr(leaf, ei) == disk_byte) {
             clone_root->offset = key.offset;
             if (clone_data_offset < data_offset &&
                 clone_data_offset + ext_len > data_offset) {
                 u64 extent_offset;
 
                 extent_offset = data_offset - clone_data_offset;
                 ext_len -= extent_offset;
                 clone_data_offset += extent_offset;
                 clone_root->offset += extent_offset;
             }
         }
 
         clone_len = min_t(u64, ext_len, len);
 
         if (btrfs_file_extent_disk_bytenr(leaf, ei) == disk_byte &&
             clone_data_offset == data_offset) {
             const u64 src_end = clone_root->offset + clone_len;
             const u64 sectorsize = SZ_64K;
 
             /*
              * We can't clone the last block, when its size is not
              * sector size aligned, into the middle of a file. If we
              * do so, the receiver will get a failure (-EINVAL) when
              * trying to clone or will silently corrupt the data in
              * the destination file if it's on a kernel without the
              * fix introduced by commit ac765f83f1397646
              * ("Btrfs: fix data corruption due to cloning of eof
              * block).
              *
              * So issue a clone of the aligned down range plus a
              * regular write for the eof block, if we hit that case.
              *
              * Also, we use the maximum possible sector size, 64K,
              * because we don't know what's the sector size of the
              * filesystem that receives the stream, so we have to
              * assume the largest possible sector size.
              */
             if (src_end == clone_src_i_size &&
                 !IS_ALIGNED(src_end, sectorsize) &&
                 offset + clone_len < sctx->cur_inode_size) {
                 u64 slen;
 
                 slen = ALIGN_DOWN(src_end - clone_root->offset,
                           sectorsize);
                 if (slen > 0) {
                     ret = send_clone(sctx, offset, slen,
                              clone_root);
                     if (ret < 0)
                         goto out;
                 }
                 ret = send_extent_data(sctx, dst_path,
                                offset + slen,
                                clone_len - slen);
             } else {
                 ret = send_clone(sctx, offset, clone_len,
                          clone_root);
             }
         } else {
             ret = send_extent_data(sctx, dst_path, offset,
                            clone_len);
         }
 
         if (ret < 0)
             goto out;
 
         len -= clone_len;
         if (len == 0)
             break;
         offset += clone_len;
         clone_root->offset += clone_len;
 
         /*
          * If we are cloning from the file we are currently processing,
          * and using the send root as the clone root, we must stop once
          * the current clone offset reaches the current eof of the file
          * at the receiver, otherwise we would issue an invalid clone
          * operation (source range going beyond eof) and cause the
          * receiver to fail. So if we reach the current eof, bail out
          * and fallback to a regular write.
          */
         if (clone_root->root == sctx->send_root &&
             clone_root->ino == sctx->cur_ino &&
             clone_root->offset >= sctx->cur_inode_next_write_offset)
             break;
 
         data_offset += clone_len;
 next:
         path->slots[0]++;
     }
 
     if (len > 0)
         ret = send_extent_data(sctx, dst_path, offset, len);
     else
         ret = 0;
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int send_write_or_clone(struct send_ctx *sctx,
                    struct btrfs_path *path,
                    struct btrfs_key *key,
                    struct clone_root *clone_root)
 {
     int ret = 0;
     u64 offset = key->offset;
     u64 end;
     u64 bs = sctx->send_root->fs_info->sb->s_blocksize;
 
     end = min_t(u64, btrfs_file_extent_end(path), sctx->cur_inode_size);
     if (offset >= end)
         return 0;
 
     if (clone_root && IS_ALIGNED(end, bs)) {
         struct btrfs_file_extent_item *ei;
         u64 disk_byte;
         u64 data_offset;
 
         ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
                     struct btrfs_file_extent_item);
         disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei);
         data_offset = btrfs_file_extent_offset(path->nodes[0], ei);
         ret = clone_range(sctx, path, clone_root, disk_byte,
                   data_offset, offset, end - offset);
     } else {
         ret = send_extent_data(sctx, path, offset, end - offset);
     }
     sctx->cur_inode_next_write_offset = end;
     return ret;
 }
 
 static int is_extent_unchanged(struct send_ctx *sctx,
                    struct btrfs_path *left_path,
                    struct btrfs_key *ekey)
 {
     int ret = 0;
     struct btrfs_key key;
     struct btrfs_path *path = NULL;
     struct extent_buffer *eb;
     int slot;
     struct btrfs_key found_key;
     struct btrfs_file_extent_item *ei;
     u64 left_disknr;
     u64 right_disknr;
     u64 left_offset;
     u64 right_offset;
     u64 left_offset_fixed;
     u64 left_len;
     u64 right_len;
     u64 left_gen;
     u64 right_gen;
     u8 left_type;
     u8 right_type;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     eb = left_path->nodes[0];
     slot = left_path->slots[0];
     ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
     left_type = btrfs_file_extent_type(eb, ei);
 
     if (left_type != BTRFS_FILE_EXTENT_REG) {
         ret = 0;
         goto out;
     }
     left_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
     left_len = btrfs_file_extent_num_bytes(eb, ei);
     left_offset = btrfs_file_extent_offset(eb, ei);
     left_gen = btrfs_file_extent_generation(eb, ei);
 
     /*
      * Following comments will refer to these graphics. L is the left
      * extents which we are checking at the moment. 1-8 are the right
      * extents that we iterate.
      *
      *       |-----L-----|
      * |-1-|-2a-|-3-|-4-|-5-|-6-|
      *
      *       |-----L-----|
      * |--1--|-2b-|...(same as above)
      *
      * Alternative situation. Happens on files where extents got split.
      *       |-----L-----|
      * |-----------7-----------|-6-|
      *
      * Alternative situation. Happens on files which got larger.
      *       |-----L-----|
      * |-8-|
      * Nothing follows after 8.
      */
 
     key.objectid = ekey->objectid;
     key.type = BTRFS_EXTENT_DATA_KEY;
     key.offset = ekey->offset;
     ret = btrfs_search_slot_for_read(sctx->parent_root, &key, path, 0, 0);
     if (ret < 0)
         goto out;
     if (ret) {
         ret = 0;
         goto out;
     }
 
     /*
      * Handle special case where the right side has no extents at all.
      */
     eb = path->nodes[0];
     slot = path->slots[0];
     btrfs_item_key_to_cpu(eb, &found_key, slot);
     if (found_key.objectid != key.objectid ||
         found_key.type != key.type) {
         /* If we're a hole then just pretend nothing changed */
         ret = (left_disknr) ? 0 : 1;
         goto out;
     }
 
     /*
      * We're now on 2a, 2b or 7.
      */
     key = found_key;
     while (key.offset < ekey->offset + left_len) {
         ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
         right_type = btrfs_file_extent_type(eb, ei);
         if (right_type != BTRFS_FILE_EXTENT_REG &&
             right_type != BTRFS_FILE_EXTENT_INLINE) {
             ret = 0;
             goto out;
         }
 
         if (right_type == BTRFS_FILE_EXTENT_INLINE) {
             right_len = btrfs_file_extent_ram_bytes(eb, ei);
             right_len = PAGE_ALIGN(right_len);
         } else {
             right_len = btrfs_file_extent_num_bytes(eb, ei);
         }
 
         /*
          * Are we at extent 8? If yes, we know the extent is changed.
          * This may only happen on the first iteration.
          */
         if (found_key.offset + right_len <= ekey->offset) {
             /* If we're a hole just pretend nothing changed */
             ret = (left_disknr) ? 0 : 1;
             goto out;
         }
 
         /*
          * We just wanted to see if when we have an inline extent, what
          * follows it is a regular extent (wanted to check the above
          * condition for inline extents too). This should normally not
          * happen but it's possible for example when we have an inline
          * compressed extent representing data with a size matching
          * the page size (currently the same as sector size).
          */
         if (right_type == BTRFS_FILE_EXTENT_INLINE) {
             ret = 0;
             goto out;
         }
 
         right_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
         right_offset = btrfs_file_extent_offset(eb, ei);
         right_gen = btrfs_file_extent_generation(eb, ei);
 
         left_offset_fixed = left_offset;
         if (key.offset < ekey->offset) {
             /* Fix the right offset for 2a and 7. */
             right_offset += ekey->offset - key.offset;
         } else {
             /* Fix the left offset for all behind 2a and 2b */
             left_offset_fixed += key.offset - ekey->offset;
         }
 
         /*
          * Check if we have the same extent.
          */
         if (left_disknr != right_disknr ||
             left_offset_fixed != right_offset ||
             left_gen != right_gen) {
             ret = 0;
             goto out;
         }
 
         /*
          * Go to the next extent.
          */
         ret = btrfs_next_item(sctx->parent_root, path);
         if (ret < 0)
             goto out;
         if (!ret) {
             eb = path->nodes[0];
             slot = path->slots[0];
             btrfs_item_key_to_cpu(eb, &found_key, slot);
         }
         if (ret || found_key.objectid != key.objectid ||
             found_key.type != key.type) {
             key.offset += right_len;
             break;
         }
         if (found_key.offset != key.offset + right_len) {
             ret = 0;
             goto out;
         }
         key = found_key;
     }
 
     /*
      * We're now behind the left extent (treat as unchanged) or at the end
      * of the right side (treat as changed).
      */
     if (key.offset >= ekey->offset + left_len)
         ret = 1;
     else
         ret = 0;
 
 
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int get_last_extent(struct send_ctx *sctx, u64 offset)
 {
     struct btrfs_path *path;
     struct btrfs_root *root = sctx->send_root;
     struct btrfs_key key;
     int ret;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     sctx->cur_inode_last_extent = 0;
 
     key.objectid = sctx->cur_ino;
     key.type = BTRFS_EXTENT_DATA_KEY;
     key.offset = offset;
     ret = btrfs_search_slot_for_read(root, &key, path, 0, 1);
     if (ret < 0)
         goto out;
     ret = 0;
     btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
     if (key.objectid != sctx->cur_ino || key.type != BTRFS_EXTENT_DATA_KEY)
         goto out;
 
     sctx->cur_inode_last_extent = btrfs_file_extent_end(path);
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int range_is_hole_in_parent(struct send_ctx *sctx,
                    const u64 start,
                    const u64 end)
 {
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_root *root = sctx->parent_root;
     u64 search_start = start;
     int ret;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     key.objectid = sctx->cur_ino;
     key.type = BTRFS_EXTENT_DATA_KEY;
     key.offset = search_start;
     ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
     if (ret < 0)
         goto out;
     if (ret > 0 && path->slots[0] > 0)
         path->slots[0]--;
 
     while (search_start < end) {
         struct extent_buffer *leaf = path->nodes[0];
         int slot = path->slots[0];
         struct btrfs_file_extent_item *fi;
         u64 extent_end;
 
         if (slot >= btrfs_header_nritems(leaf)) {
             ret = btrfs_next_leaf(root, path);
             if (ret < 0)
                 goto out;
             else if (ret > 0)
                 break;
             continue;
         }
 
         btrfs_item_key_to_cpu(leaf, &key, slot);
         if (key.objectid < sctx->cur_ino ||
             key.type < BTRFS_EXTENT_DATA_KEY)
             goto next;
         if (key.objectid > sctx->cur_ino ||
             key.type > BTRFS_EXTENT_DATA_KEY ||
             key.offset >= end)
             break;
 
         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
         extent_end = btrfs_file_extent_end(path);
         if (extent_end <= start)
             goto next;
         if (btrfs_file_extent_disk_bytenr(leaf, fi) == 0) {
             search_start = extent_end;
             goto next;
         }
         ret = 0;
         goto out;
 next:
         path->slots[0]++;
     }
     ret = 1;
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int maybe_send_hole(struct send_ctx *sctx, struct btrfs_path *path,
                struct btrfs_key *key)
 {
     int ret = 0;
 
     if (sctx->cur_ino != key->objectid || !need_send_hole(sctx))
         return 0;
 
     if (sctx->cur_inode_last_extent == (u64)-1) {
         ret = get_last_extent(sctx, key->offset - 1);
         if (ret)
             return ret;
     }
 
     if (path->slots[0] == 0 &&
         sctx->cur_inode_last_extent < key->offset) {
         /*
          * We might have skipped entire leafs that contained only
          * file extent items for our current inode. These leafs have
          * a generation number smaller (older) than the one in the
          * current leaf and the leaf our last extent came from, and
          * are located between these 2 leafs.
          */
         ret = get_last_extent(sctx, key->offset - 1);
         if (ret)
             return ret;
     }
 
     if (sctx->cur_inode_last_extent < key->offset) {
         ret = range_is_hole_in_parent(sctx,
                           sctx->cur_inode_last_extent,
                           key->offset);
         if (ret < 0)
             return ret;
         else if (ret == 0)
             ret = send_hole(sctx, key->offset);
         else
             ret = 0;
     }
     sctx->cur_inode_last_extent = btrfs_file_extent_end(path);
     return ret;
 }
 
 static int process_extent(struct send_ctx *sctx,
               struct btrfs_path *path,
               struct btrfs_key *key)
 {
     struct clone_root *found_clone = NULL;
     int ret = 0;
 
     if (S_ISLNK(sctx->cur_inode_mode))
         return 0;
 
     if (sctx->parent_root && !sctx->cur_inode_new) {
         ret = is_extent_unchanged(sctx, path, key);
         if (ret < 0)
             goto out;
         if (ret) {
             ret = 0;
             goto out_hole;
         }
     } else {
         struct btrfs_file_extent_item *ei;
         u8 type;
 
         ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
                     struct btrfs_file_extent_item);
         type = btrfs_file_extent_type(path->nodes[0], ei);
         if (type == BTRFS_FILE_EXTENT_PREALLOC ||
             type == BTRFS_FILE_EXTENT_REG) {
             /*
              * The send spec does not have a prealloc command yet,
              * so just leave a hole for prealloc'ed extents until
              * we have enough commands queued up to justify rev'ing
              * the send spec.
              */
             if (type == BTRFS_FILE_EXTENT_PREALLOC) {
                 ret = 0;
                 goto out;
             }
 
             /* Have a hole, just skip it. */
             if (btrfs_file_extent_disk_bytenr(path->nodes[0], ei) == 0) {
                 ret = 0;
                 goto out;
             }
         }
     }
 
     ret = find_extent_clone(sctx, path, key->objectid, key->offset,
             sctx->cur_inode_size, &found_clone);
     if (ret != -ENOENT && ret < 0)
         goto out;
 
     ret = send_write_or_clone(sctx, path, key, found_clone);
     if (ret)
         goto out;
 out_hole:
     ret = maybe_send_hole(sctx, path, key);
 out:
     return ret;
 }
 
 static int process_all_extents(struct send_ctx *sctx)
 {
     int ret = 0;
     int iter_ret = 0;
     struct btrfs_root *root;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_key found_key;
 
     root = sctx->send_root;
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     key.objectid = sctx->cmp_key->objectid;
     key.type = BTRFS_EXTENT_DATA_KEY;
     key.offset = 0;
     btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
         if (found_key.objectid != key.objectid ||
             found_key.type != key.type) {
             ret = 0;
             break;
         }
 
         ret = process_extent(sctx, path, &found_key);
         if (ret < 0)
             break;
     }
     /* Catch error found during iteration */
     if (iter_ret < 0)
         ret = iter_ret;
 
     btrfs_free_path(path);
     return ret;
 }
 
 static int process_recorded_refs_if_needed(struct send_ctx *sctx, int at_end,
                        int *pending_move,
                        int *refs_processed)
 {
     int ret = 0;
 
     if (sctx->cur_ino == 0)
         goto out;
     if (!at_end && sctx->cur_ino == sctx->cmp_key->objectid &&
         sctx->cmp_key->type <= BTRFS_INODE_EXTREF_KEY)
         goto out;
     if (list_empty(&sctx->new_refs) && list_empty(&sctx->deleted_refs))
         goto out;
 
     ret = process_recorded_refs(sctx, pending_move);
     if (ret < 0)
         goto out;
 
     *refs_processed = 1;
 out:
     return ret;
 }
 
 static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
 {
     int ret = 0;
     u64 left_mode;
     u64 left_uid;
     u64 left_gid;
     u64 left_fileattr;
     u64 right_mode;
     u64 right_uid;
     u64 right_gid;
     u64 right_fileattr;
     int need_chmod = 0;
     int need_chown = 0;
     bool need_fileattr = false;
     int need_truncate = 1;
     int pending_move = 0;
     int refs_processed = 0;
 
     if (sctx->ignore_cur_inode)
         return 0;
 
     ret = process_recorded_refs_if_needed(sctx, at_end, &pending_move,
                           &refs_processed);
     if (ret < 0)
         goto out;
 
     /*
      * We have processed the refs and thus need to advance send_progress.
      * Now, calls to get_cur_xxx will take the updated refs of the current
      * inode into account.
      *
      * On the other hand, if our current inode is a directory and couldn't
      * be moved/renamed because its parent was renamed/moved too and it has
      * a higher inode number, we can only move/rename our current inode
      * after we moved/renamed its parent. Therefore in this case operate on
      * the old path (pre move/rename) of our current inode, and the
      * move/rename will be performed later.
      */
     if (refs_processed && !pending_move)
         sctx->send_progress = sctx->cur_ino + 1;
 
     if (sctx->cur_ino == 0 || sctx->cur_inode_deleted)
         goto out;
     if (!at_end && sctx->cmp_key->objectid == sctx->cur_ino)
         goto out;
 
     ret = get_inode_info(sctx->send_root, sctx->cur_ino, NULL, NULL,
             &left_mode, &left_uid, &left_gid, NULL, &left_fileattr);
     if (ret < 0)
         goto out;
 
     if (!sctx->parent_root || sctx->cur_inode_new) {
         need_chown = 1;
         if (!S_ISLNK(sctx->cur_inode_mode))
             need_chmod = 1;
         if (sctx->cur_inode_next_write_offset == sctx->cur_inode_size)
             need_truncate = 0;
     } else {
         u64 old_size;
 
         ret = get_inode_info(sctx->parent_root, sctx->cur_ino,
                 &old_size, NULL, &right_mode, &right_uid,
                 &right_gid, NULL, &right_fileattr);
         if (ret < 0)
             goto out;
 
         if (left_uid != right_uid || left_gid != right_gid)
             need_chown = 1;
         if (!S_ISLNK(sctx->cur_inode_mode) && left_mode != right_mode)
             need_chmod = 1;
         if (!S_ISLNK(sctx->cur_inode_mode) && left_fileattr != right_fileattr)
             need_fileattr = true;
         if ((old_size == sctx->cur_inode_size) ||
             (sctx->cur_inode_size > old_size &&
              sctx->cur_inode_next_write_offset == sctx->cur_inode_size))
             need_truncate = 0;
     }
 
     if (S_ISREG(sctx->cur_inode_mode)) {
         if (need_send_hole(sctx)) {
             if (sctx->cur_inode_last_extent == (u64)-1 ||
                 sctx->cur_inode_last_extent <
                 sctx->cur_inode_size) {
                 ret = get_last_extent(sctx, (u64)-1);
                 if (ret)
                     goto out;
             }
             if (sctx->cur_inode_last_extent <
                 sctx->cur_inode_size) {
                 ret = send_hole(sctx, sctx->cur_inode_size);
                 if (ret)
                     goto out;
             }
         }
         if (need_truncate) {
             ret = send_truncate(sctx, sctx->cur_ino,
                         sctx->cur_inode_gen,
                         sctx->cur_inode_size);
             if (ret < 0)
                 goto out;
         }
     }
 
     if (need_chown) {
         ret = send_chown(sctx, sctx->cur_ino, sctx->cur_inode_gen,
                 left_uid, left_gid);
         if (ret < 0)
             goto out;
     }
     if (need_chmod) {
         ret = send_chmod(sctx, sctx->cur_ino, sctx->cur_inode_gen,
                 left_mode);
         if (ret < 0)
             goto out;
     }
     if (need_fileattr) {
         ret = send_fileattr(sctx, sctx->cur_ino, sctx->cur_inode_gen,
                     left_fileattr);
         if (ret < 0)
             goto out;
     }
 
     ret = send_capabilities(sctx);
     if (ret < 0)
         goto out;
 
     /*
      * If other directory inodes depended on our current directory
      * inode's move/rename, now do their move/rename operations.
      */
     if (!is_waiting_for_move(sctx, sctx->cur_ino)) {
         ret = apply_children_dir_moves(sctx);
         if (ret)
             goto out;
         /*
          * Need to send that every time, no matter if it actually
          * changed between the two trees as we have done changes to
          * the inode before. If our inode is a directory and it's
          * waiting to be moved/renamed, we will send its utimes when
          * it's moved/renamed, therefore we don't need to do it here.
          */
         sctx->send_progress = sctx->cur_ino + 1;
         ret = send_utimes(sctx, sctx->cur_ino, sctx->cur_inode_gen);
         if (ret < 0)
             goto out;
     }
 
 out:
     return ret;
 }
 
 struct parent_paths_ctx {
     struct list_head *refs;
     struct send_ctx *sctx;
 };
 
 static int record_parent_ref(int num, u64 dir, int index, struct fs_path *name,
                  void *ctx)
 {
     struct parent_paths_ctx *ppctx = ctx;
 
     /*
      * Pass 0 as the generation for the directory, we don't care about it
      * here as we have no new references to add, we just want to delete all
      * references for an inode.
      */
     return record_ref_in_tree(&ppctx->sctx->rbtree_deleted_refs, ppctx->refs,
                   name, dir, 0, ppctx->sctx);
 }
 
 /*
  * Issue unlink operations for all paths of the current inode found in the
  * parent snapshot.
  */
 static int btrfs_unlink_all_paths(struct send_ctx *sctx)
 {
     LIST_HEAD(deleted_refs);
     struct btrfs_path *path;
     struct btrfs_root *root = sctx->parent_root;
     struct btrfs_key key;
     struct btrfs_key found_key;
     struct parent_paths_ctx ctx;
     int iter_ret = 0;
     int ret;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
 
     key.objectid = sctx->cur_ino;
     key.type = BTRFS_INODE_REF_KEY;
     key.offset = 0;
 
     ctx.refs = &deleted_refs;
     ctx.sctx = sctx;
 
     btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
         if (found_key.objectid != key.objectid)
             break;
         if (found_key.type != key.type &&
             found_key.type != BTRFS_INODE_EXTREF_KEY)
             break;
 
         ret = iterate_inode_ref(root, path, &found_key, 1,
                     record_parent_ref, &ctx);
         if (ret < 0)
             goto out;
     }
     /* Catch error found during iteration */
     if (iter_ret < 0) {
         ret = iter_ret;
         goto out;
     }
 
     while (!list_empty(&deleted_refs)) {
         struct recorded_ref *ref;
 
         ref = list_first_entry(&deleted_refs, struct recorded_ref, list);
         ret = send_unlink(sctx, ref->full_path);
         if (ret < 0)
             goto out;
         recorded_ref_free(ref);
     }
     ret = 0;
 out:
     btrfs_free_path(path);
     if (ret)
         __free_recorded_refs(&deleted_refs);
     return ret;
 }
 
 static void close_current_inode(struct send_ctx *sctx)
 {
     u64 i_size;
 
     if (sctx->cur_inode == NULL)
         return;
 
     i_size = i_size_read(sctx->cur_inode);
 
     /*
      * If we are doing an incremental send, we may have extents between the
      * last processed extent and the i_size that have not been processed
      * because they haven't changed but we may have read some of their pages
      * through readahead, see the comments at send_extent_data().
      */
     if (sctx->clean_page_cache && sctx->page_cache_clear_start < i_size)
         truncate_inode_pages_range(&sctx->cur_inode->i_data,
                        sctx->page_cache_clear_start,
                        round_up(i_size, PAGE_SIZE) - 1);
 
     iput(sctx->cur_inode);
     sctx->cur_inode = NULL;
 }
 
 static int changed_inode(struct send_ctx *sctx,
              enum btrfs_compare_tree_result result)
 {
     int ret = 0;
     struct btrfs_key *key = sctx->cmp_key;
     struct btrfs_inode_item *left_ii = NULL;
     struct btrfs_inode_item *right_ii = NULL;
     u64 left_gen = 0;
     u64 right_gen = 0;
 
     close_current_inode(sctx);
 
     sctx->cur_ino = key->objectid;
     sctx->cur_inode_new_gen = false;
     sctx->cur_inode_last_extent = (u64)-1;
     sctx->cur_inode_next_write_offset = 0;
     sctx->ignore_cur_inode = false;
 
     /*
      * Set send_progress to current inode. This will tell all get_cur_xxx
      * functions that the current inode's refs are not updated yet. Later,
      * when process_recorded_refs is finished, it is set to cur_ino + 1.
      */
     sctx->send_progress = sctx->cur_ino;
 
     if (result == BTRFS_COMPARE_TREE_NEW ||
         result == BTRFS_COMPARE_TREE_CHANGED) {
         left_ii = btrfs_item_ptr(sctx->left_path->nodes[0],
                 sctx->left_path->slots[0],
                 struct btrfs_inode_item);
         left_gen = btrfs_inode_generation(sctx->left_path->nodes[0],
                 left_ii);
     } else {
         right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
                 sctx->right_path->slots[0],
                 struct btrfs_inode_item);
         right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
                 right_ii);
     }
     if (result == BTRFS_COMPARE_TREE_CHANGED) {
         right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
                 sctx->right_path->slots[0],
                 struct btrfs_inode_item);
 
         right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
                 right_ii);
 
         /*
          * The cur_ino = root dir case is special here. We can't treat
          * the inode as deleted+reused because it would generate a
          * stream that tries to delete/mkdir the root dir.
          */
         if (left_gen != right_gen &&
             sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
             sctx->cur_inode_new_gen = true;
     }
 
     /*
      * Normally we do not find inodes with a link count of zero (orphans)
      * because the most common case is to create a snapshot and use it
      * for a send operation. However other less common use cases involve
      * using a subvolume and send it after turning it to RO mode just
      * after deleting all hard links of a file while holding an open
      * file descriptor against it or turning a RO snapshot into RW mode,
      * keep an open file descriptor against a file, delete it and then
      * turn the snapshot back to RO mode before using it for a send
      * operation. So if we find such cases, ignore the inode and all its
      * items completely if it's a new inode, or if it's a changed inode
      * make sure all its previous paths (from the parent snapshot) are all
      * unlinked and all other the inode items are ignored.
      */
     if (result == BTRFS_COMPARE_TREE_NEW ||
         result == BTRFS_COMPARE_TREE_CHANGED) {
         u32 nlinks;
 
         nlinks = btrfs_inode_nlink(sctx->left_path->nodes[0], left_ii);
         if (nlinks == 0) {
             sctx->ignore_cur_inode = true;
             if (result == BTRFS_COMPARE_TREE_CHANGED)
                 ret = btrfs_unlink_all_paths(sctx);
             goto out;
         }
     }
 
     if (result == BTRFS_COMPARE_TREE_NEW) {
         sctx->cur_inode_gen = left_gen;
         sctx->cur_inode_new = true;
         sctx->cur_inode_deleted = false;
         sctx->cur_inode_size = btrfs_inode_size(
                 sctx->left_path->nodes[0], left_ii);
         sctx->cur_inode_mode = btrfs_inode_mode(
                 sctx->left_path->nodes[0], left_ii);
         sctx->cur_inode_rdev = btrfs_inode_rdev(
                 sctx->left_path->nodes[0], left_ii);
         if (sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
             ret = send_create_inode_if_needed(sctx);
     } else if (result == BTRFS_COMPARE_TREE_DELETED) {
         sctx->cur_inode_gen = right_gen;
         sctx->cur_inode_new = false;
         sctx->cur_inode_deleted = true;
         sctx->cur_inode_size = btrfs_inode_size(
                 sctx->right_path->nodes[0], right_ii);
         sctx->cur_inode_mode = btrfs_inode_mode(
                 sctx->right_path->nodes[0], right_ii);
     } else if (result == BTRFS_COMPARE_TREE_CHANGED) {
         /*
          * We need to do some special handling in case the inode was
          * reported as changed with a changed generation number. This
          * means that the original inode was deleted and new inode
          * reused the same inum. So we have to treat the old inode as
          * deleted and the new one as new.
          */
         if (sctx->cur_inode_new_gen) {
             /*
              * First, process the inode as if it was deleted.
              */
             sctx->cur_inode_gen = right_gen;
             sctx->cur_inode_new = false;
             sctx->cur_inode_deleted = true;
             sctx->cur_inode_size = btrfs_inode_size(
                     sctx->right_path->nodes[0], right_ii);
             sctx->cur_inode_mode = btrfs_inode_mode(
                     sctx->right_path->nodes[0], right_ii);
             ret = process_all_refs(sctx,
                     BTRFS_COMPARE_TREE_DELETED);
             if (ret < 0)
                 goto out;
 
             /*
              * Now process the inode as if it was new.
              */
             sctx->cur_inode_gen = left_gen;
             sctx->cur_inode_new = true;
             sctx->cur_inode_deleted = false;
             sctx->cur_inode_size = btrfs_inode_size(
                     sctx->left_path->nodes[0], left_ii);
             sctx->cur_inode_mode = btrfs_inode_mode(
                     sctx->left_path->nodes[0], left_ii);
             sctx->cur_inode_rdev = btrfs_inode_rdev(
                     sctx->left_path->nodes[0], left_ii);
             ret = send_create_inode_if_needed(sctx);
             if (ret < 0)
                 goto out;
 
             ret = process_all_refs(sctx, BTRFS_COMPARE_TREE_NEW);
             if (ret < 0)
                 goto out;
             /*
              * Advance send_progress now as we did not get into
              * process_recorded_refs_if_needed in the new_gen case.
              */
             sctx->send_progress = sctx->cur_ino + 1;
 
             /*
              * Now process all extents and xattrs of the inode as if
              * they were all new.
              */
             ret = process_all_extents(sctx);
             if (ret < 0)
                 goto out;
             ret = process_all_new_xattrs(sctx);
             if (ret < 0)
                 goto out;
         } else {
             sctx->cur_inode_gen = left_gen;
             sctx->cur_inode_new = false;
             sctx->cur_inode_new_gen = false;
             sctx->cur_inode_deleted = false;
             sctx->cur_inode_size = btrfs_inode_size(
                     sctx->left_path->nodes[0], left_ii);
             sctx->cur_inode_mode = btrfs_inode_mode(
                     sctx->left_path->nodes[0], left_ii);
         }
     }
 
 out:
     return ret;
 }
 
 /*
  * We have to process new refs before deleted refs, but compare_trees gives us
  * the new and deleted refs mixed. To fix this, we record the new/deleted refs
  * first and later process them in process_recorded_refs.
  * For the cur_inode_new_gen case, we skip recording completely because
  * changed_inode did already initiate processing of refs. The reason for this is
  * that in this case, compare_tree actually compares the refs of 2 different
  * inodes. To fix this, process_all_refs is used in changed_inode to handle all
  * refs of the right tree as deleted and all refs of the left tree as new.
  */
 static int changed_ref(struct send_ctx *sctx,
                enum btrfs_compare_tree_result result)
 {
     int ret = 0;
 
     if (sctx->cur_ino != sctx->cmp_key->objectid) {
         inconsistent_snapshot_error(sctx, result, "reference");
         return -EIO;
     }
 
     if (!sctx->cur_inode_new_gen &&
         sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID) {
         if (result == BTRFS_COMPARE_TREE_NEW)
             ret = record_new_ref(sctx);
         else if (result == BTRFS_COMPARE_TREE_DELETED)
             ret = record_deleted_ref(sctx);
         else if (result == BTRFS_COMPARE_TREE_CHANGED)
             ret = record_changed_ref(sctx);
     }
 
     return ret;
 }
 
 /*
  * Process new/deleted/changed xattrs. We skip processing in the
  * cur_inode_new_gen case because changed_inode did already initiate processing
  * of xattrs. The reason is the same as in changed_ref
  */
 static int changed_xattr(struct send_ctx *sctx,
              enum btrfs_compare_tree_result result)
 {
     int ret = 0;
 
     if (sctx->cur_ino != sctx->cmp_key->objectid) {
         inconsistent_snapshot_error(sctx, result, "xattr");
         return -EIO;
     }
 
     if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
         if (result == BTRFS_COMPARE_TREE_NEW)
             ret = process_new_xattr(sctx);
         else if (result == BTRFS_COMPARE_TREE_DELETED)
             ret = process_deleted_xattr(sctx);
         else if (result == BTRFS_COMPARE_TREE_CHANGED)
             ret = process_changed_xattr(sctx);
     }
 
     return ret;
 }
 
 /*
  * Process new/deleted/changed extents. We skip processing in the
  * cur_inode_new_gen case because changed_inode did already initiate processing
  * of extents. The reason is the same as in changed_ref
  */
 static int changed_extent(struct send_ctx *sctx,
               enum btrfs_compare_tree_result result)
 {
     int ret = 0;
 
     /*
      * We have found an extent item that changed without the inode item
      * having changed. This can happen either after relocation (where the
      * disk_bytenr of an extent item is replaced at
      * relocation.c:replace_file_extents()) or after deduplication into a
      * file in both the parent and send snapshots (where an extent item can
      * get modified or replaced with a new one). Note that deduplication
      * updates the inode item, but it only changes the iversion (sequence
      * field in the inode item) of the inode, so if a file is deduplicated
      * the same amount of times in both the parent and send snapshots, its
      * iversion becomes the same in both snapshots, whence the inode item is
      * the same on both snapshots.
      */
     if (sctx->cur_ino != sctx->cmp_key->objectid)
         return 0;
 
     if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
         if (result != BTRFS_COMPARE_TREE_DELETED)
             ret = process_extent(sctx, sctx->left_path,
                     sctx->cmp_key);
     }
 
     return ret;
 }
 
 static int dir_changed(struct send_ctx *sctx, u64 dir)
 {
     u64 orig_gen, new_gen;
     int ret;
 
     ret = get_inode_info(sctx->send_root, dir, NULL, &new_gen, NULL, NULL,
                  NULL, NULL, NULL);
     if (ret)
         return ret;
 
     ret = get_inode_info(sctx->parent_root, dir, NULL, &orig_gen, NULL,
                  NULL, NULL, NULL, NULL);
     if (ret)
         return ret;
 
     return (orig_gen != new_gen) ? 1 : 0;
 }
 
 static int compare_refs(struct send_ctx *sctx, struct btrfs_path *path,
             struct btrfs_key *key)
 {
     struct btrfs_inode_extref *extref;
     struct extent_buffer *leaf;
     u64 dirid = 0, last_dirid = 0;
     unsigned long ptr;
     u32 item_size;
     u32 cur_offset = 0;
     int ref_name_len;
     int ret = 0;
 
     /* Easy case, just check this one dirid */
     if (key->type == BTRFS_INODE_REF_KEY) {
         dirid = key->offset;
 
         ret = dir_changed(sctx, dirid);
         goto out;
     }
 
     leaf = path->nodes[0];
     item_size = btrfs_item_size(leaf, path->slots[0]);
     ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
     while (cur_offset < item_size) {
         extref = (struct btrfs_inode_extref *)(ptr +
                                cur_offset);
         dirid = btrfs_inode_extref_parent(leaf, extref);
         ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
         cur_offset += ref_name_len + sizeof(*extref);
         if (dirid == last_dirid)
             continue;
         ret = dir_changed(sctx, dirid);
         if (ret)
             break;
         last_dirid = dirid;
     }
 out:
     return ret;
 }
 
 /*
  * Updates compare related fields in sctx and simply forwards to the actual
  * changed_xxx functions.
  */
 static int changed_cb(struct btrfs_path *left_path,
               struct btrfs_path *right_path,
               struct btrfs_key *key,
               enum btrfs_compare_tree_result result,
               struct send_ctx *sctx)
 {
     int ret = 0;
 
     /*
      * We can not hold the commit root semaphore here. This is because in
      * the case of sending and receiving to the same filesystem, using a
      * pipe, could result in a deadlock:
      *
      * 1) The task running send blocks on the pipe because it's full;
      *
      * 2) The task running receive, which is the only consumer of the pipe,
      *    is waiting for a transaction commit (for example due to a space
      *    reservation when doing a write or triggering a transaction commit
      *    when creating a subvolume);
      *
      * 3) The transaction is waiting to write lock the commit root semaphore,
      *    but can not acquire it since it's being held at 1).
      *
      * Down this call chain we write to the pipe through kernel_write().
      * The same type of problem can also happen when sending to a file that
      * is stored in the same filesystem - when reserving space for a write
      * into the file, we can trigger a transaction commit.
      *
      * Our caller has supplied us with clones of leaves from the send and
      * parent roots, so we're safe here from a concurrent relocation and
      * further reallocation of metadata extents while we are here. Below we
      * also assert that the leaves are clones.
      */
     lockdep_assert_not_held(&sctx->send_root->fs_info->commit_root_sem);
 
     /*
      * We always have a send root, so left_path is never NULL. We will not
      * have a leaf when we have reached the end of the send root but have
      * not yet reached the end of the parent root.
      */
     if (left_path->nodes[0])
         ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED,
                 &left_path->nodes[0]->bflags));
     /*
      * When doing a full send we don't have a parent root, so right_path is
      * NULL. When doing an incremental send, we may have reached the end of
      * the parent root already, so we don't have a leaf at right_path.
      */
     if (right_path && right_path->nodes[0])
         ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED,
                 &right_path->nodes[0]->bflags));
 
     if (result == BTRFS_COMPARE_TREE_SAME) {
         if (key->type == BTRFS_INODE_REF_KEY ||
             key->type == BTRFS_INODE_EXTREF_KEY) {
             ret = compare_refs(sctx, left_path, key);
             if (!ret)
                 return 0;
             if (ret < 0)
                 return ret;
         } else if (key->type == BTRFS_EXTENT_DATA_KEY) {
             return maybe_send_hole(sctx, left_path, key);
         } else {
             return 0;
         }
         result = BTRFS_COMPARE_TREE_CHANGED;
         ret = 0;
     }
 
     sctx->left_path = left_path;
     sctx->right_path = right_path;
     sctx->cmp_key = key;
 
     ret = finish_inode_if_needed(sctx, 0);
     if (ret < 0)
         goto out;
 
     /* Ignore non-FS objects */
     if (key->objectid == BTRFS_FREE_INO_OBJECTID ||
         key->objectid == BTRFS_FREE_SPACE_OBJECTID)
         goto out;
 
     if (key->type == BTRFS_INODE_ITEM_KEY) {
         ret = changed_inode(sctx, result);
     } else if (!sctx->ignore_cur_inode) {
         if (key->type == BTRFS_INODE_REF_KEY ||
             key->type == BTRFS_INODE_EXTREF_KEY)
             ret = changed_ref(sctx, result);
         else if (key->type == BTRFS_XATTR_ITEM_KEY)
             ret = changed_xattr(sctx, result);
         else if (key->type == BTRFS_EXTENT_DATA_KEY)
             ret = changed_extent(sctx, result);
     }
 
 out:
     return ret;
 }
 
 static int search_key_again(const struct send_ctx *sctx,
                 struct btrfs_root *root,
                 struct btrfs_path *path,
                 const struct btrfs_key *key)
 {
     int ret;
 
     if (!path->need_commit_sem)
         lockdep_assert_held_read(&root->fs_info->commit_root_sem);
 
     /*
      * Roots used for send operations are readonly and no one can add,
      * update or remove keys from them, so we should be able to find our
      * key again. The only exception is deduplication, which can operate on
      * readonly roots and add, update or remove keys to/from them - but at
      * the moment we don't allow it to run in parallel with send.
      */
     ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
     ASSERT(ret <= 0);
     if (ret > 0) {
         btrfs_print_tree(path->nodes[path->lowest_level], false);
         btrfs_err(root->fs_info,
 "send: key (%llu %u %llu) not found in %s root %llu, lowest_level %d, slot %d",
               key->objectid, key->type, key->offset,
               (root == sctx->parent_root ? "parent" : "send"),
               root->root_key.objectid, path->lowest_level,
               path->slots[path->lowest_level]);
         return -EUCLEAN;
     }
 
     return ret;
 }
 
 static int full_send_tree(struct send_ctx *sctx)
 {
     int ret;
     struct btrfs_root *send_root = sctx->send_root;
     struct btrfs_key key;
     struct btrfs_fs_info *fs_info = send_root->fs_info;
     struct btrfs_path *path;
 
     path = alloc_path_for_send();
     if (!path)
         return -ENOMEM;
     path->reada = READA_FORWARD_ALWAYS;
 
     key.objectid = BTRFS_FIRST_FREE_OBJECTID;
     key.type = BTRFS_INODE_ITEM_KEY;
     key.offset = 0;
 
     down_read(&fs_info->commit_root_sem);
     sctx->last_reloc_trans = fs_info->last_reloc_trans;
     up_read(&fs_info->commit_root_sem);
 
     ret = btrfs_search_slot_for_read(send_root, &key, path, 1, 0);
     if (ret < 0)
         goto out;
     if (ret)
         goto out_finish;
 
     while (1) {
         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 
         ret = changed_cb(path, NULL, &key,
                  BTRFS_COMPARE_TREE_NEW, sctx);
         if (ret < 0)
             goto out;
 
         down_read(&fs_info->commit_root_sem);
         if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
             sctx->last_reloc_trans = fs_info->last_reloc_trans;
             up_read(&fs_info->commit_root_sem);
             /*
              * A transaction used for relocating a block group was
              * committed or is about to finish its commit. Release
              * our path (leaf) and restart the search, so that we
              * avoid operating on any file extent items that are
              * stale, with a disk_bytenr that reflects a pre
              * relocation value. This way we avoid as much as
              * possible to fallback to regular writes when checking
              * if we can clone file ranges.
              */
             btrfs_release_path(path);
             ret = search_key_again(sctx, send_root, path, &key);
             if (ret < 0)
                 goto out;
         } else {
             up_read(&fs_info->commit_root_sem);
         }
 
         ret = btrfs_next_item(send_root, path);
         if (ret < 0)
             goto out;
         if (ret) {
             ret  = 0;
             break;
         }
     }
 
 out_finish:
     ret = finish_inode_if_needed(sctx, 1);
 
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int replace_node_with_clone(struct btrfs_path *path, int level)
 {
     struct extent_buffer *clone;
 
     clone = btrfs_clone_extent_buffer(path->nodes[level]);
     if (!clone)
         return -ENOMEM;
 
     free_extent_buffer(path->nodes[level]);
     path->nodes[level] = clone;
 
     return 0;
 }
 
 static int tree_move_down(struct btrfs_path *path, int *level, u64 reada_min_gen)
 {
     struct extent_buffer *eb;
     struct extent_buffer *parent = path->nodes[*level];
     int slot = path->slots[*level];
     const int nritems = btrfs_header_nritems(parent);
     u64 reada_max;
     u64 reada_done = 0;
 
     lockdep_assert_held_read(&parent->fs_info->commit_root_sem);
 
     BUG_ON(*level == 0);
     eb = btrfs_read_node_slot(parent, slot);
     if (IS_ERR(eb))
         return PTR_ERR(eb);
 
     /*
      * Trigger readahead for the next leaves we will process, so that it is
      * very likely that when we need them they are already in memory and we
      * will not block on disk IO. For nodes we only do readahead for one,
      * since the time window between processing nodes is typically larger.
      */
     reada_max = (*level == 1 ? SZ_128K : eb->fs_info->nodesize);
 
     for (slot++; slot < nritems && reada_done < reada_max; slot++) {
         if (btrfs_node_ptr_generation(parent, slot) > reada_min_gen) {
             btrfs_readahead_node_child(parent, slot);
             reada_done += eb->fs_info->nodesize;
         }
     }
 
     path->nodes[*level - 1] = eb;
     path->slots[*level - 1] = 0;
     (*level)--;
 
     if (*level == 0)
         return replace_node_with_clone(path, 0);
 
     return 0;
 }
 
 static int tree_move_next_or_upnext(struct btrfs_path *path,
                     int *level, int root_level)
 {
     int ret = 0;
     int nritems;
     nritems = btrfs_header_nritems(path->nodes[*level]);
 
     path->slots[*level]++;
 
     while (path->slots[*level] >= nritems) {
         if (*level == root_level) {
             path->slots[*level] = nritems - 1;
             return -1;
         }
 
         /* move upnext */
         path->slots[*level] = 0;
         free_extent_buffer(path->nodes[*level]);
         path->nodes[*level] = NULL;
         (*level)++;
         path->slots[*level]++;
 
         nritems = btrfs_header_nritems(path->nodes[*level]);
         ret = 1;
     }
     return ret;
 }
 
 /*
  * Returns 1 if it had to move up and next. 0 is returned if it moved only next
  * or down.
  */
 static int tree_advance(struct btrfs_path *path,
             int *level, int root_level,
             int allow_down,
             struct btrfs_key *key,
             u64 reada_min_gen)
 {
     int ret;
 
     if (*level == 0 || !allow_down) {
         ret = tree_move_next_or_upnext(path, level, root_level);
     } else {
         ret = tree_move_down(path, level, reada_min_gen);
     }
 
     /*
      * Even if we have reached the end of a tree, ret is -1, update the key
      * anyway, so that in case we need to restart due to a block group
      * relocation, we can assert that the last key of the root node still
      * exists in the tree.
      */
     if (*level == 0)
         btrfs_item_key_to_cpu(path->nodes[*level], key,
                       path->slots[*level]);
     else
         btrfs_node_key_to_cpu(path->nodes[*level], key,
                       path->slots[*level]);
 
     return ret;
 }
 
 static int tree_compare_item(struct btrfs_path *left_path,
                  struct btrfs_path *right_path,
                  char *tmp_buf)
 {
     int cmp;
     int len1, len2;
     unsigned long off1, off2;
 
     len1 = btrfs_item_size(left_path->nodes[0], left_path->slots[0]);
     len2 = btrfs_item_size(right_path->nodes[0], right_path->slots[0]);
     if (len1 != len2)
         return 1;
 
     off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
     off2 = btrfs_item_ptr_offset(right_path->nodes[0],
                 right_path->slots[0]);
 
     read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
 
     cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
     if (cmp)
         return 1;
     return 0;
 }
 
 /*
  * A transaction used for relocating a block group was committed or is about to
  * finish its commit. Release our paths and restart the search, so that we are
  * not using stale extent buffers:
  *
  * 1) For levels > 0, we are only holding references of extent buffers, without
  *    any locks on them, which does not prevent them from having been relocated
  *    and reallocated after the last time we released the commit root semaphore.
  *    The exception are the root nodes, for which we always have a clone, see
  *    the comment at btrfs_compare_trees();
  *
  * 2) For leaves, level 0, we are holding copies (clones) of extent buffers, so
  *    we are safe from the concurrent relocation and reallocation. However they
  *    can have file extent items with a pre relocation disk_bytenr value, so we
  *    restart the start from the current commit roots and clone the new leaves so
  *    that we get the post relocation disk_bytenr values. Not doing so, could
  *    make us clone the wrong data in case there are new extents using the old
  *    disk_bytenr that happen to be shared.
  */
 static int restart_after_relocation(struct btrfs_path *left_path,
                     struct btrfs_path *right_path,
                     const struct btrfs_key *left_key,
                     const struct btrfs_key *right_key,
                     int left_level,
                     int right_level,
                     const struct send_ctx *sctx)
 {
     int root_level;
     int ret;
 
     lockdep_assert_held_read(&sctx->send_root->fs_info->commit_root_sem);
 
     btrfs_release_path(left_path);
     btrfs_release_path(right_path);
 
     /*
      * Since keys can not be added or removed to/from our roots because they
      * are readonly and we do not allow deduplication to run in parallel
      * (which can add, remove or change keys), the layout of the trees should
      * not change.
      */
     left_path->lowest_level = left_level;
     ret = search_key_again(sctx, sctx->send_root, left_path, left_key);
     if (ret < 0)
         return ret;
 
     right_path->lowest_level = right_level;
     ret = search_key_again(sctx, sctx->parent_root, right_path, right_key);
     if (ret < 0)
         return ret;
 
     /*
      * If the lowest level nodes are leaves, clone them so that they can be
      * safely used by changed_cb() while not under the protection of the
      * commit root semaphore, even if relocation and reallocation happens in
      * parallel.
      */
     if (left_level == 0) {
         ret = replace_node_with_clone(left_path, 0);
         if (ret < 0)
             return ret;
     }
 
     if (right_level == 0) {
         ret = replace_node_with_clone(right_path, 0);
         if (ret < 0)
             return ret;
     }
 
     /*
      * Now clone the root nodes (unless they happen to be the leaves we have
      * already cloned). This is to protect against concurrent snapshotting of
      * the send and parent roots (see the comment at btrfs_compare_trees()).
      */
     root_level = btrfs_header_level(sctx->send_root->commit_root);
     if (root_level > 0) {
         ret = replace_node_with_clone(left_path, root_level);
         if (ret < 0)
             return ret;
     }
 
     root_level = btrfs_header_level(sctx->parent_root->commit_root);
     if (root_level > 0) {
         ret = replace_node_with_clone(right_path, root_level);
         if (ret < 0)
             return ret;
     }
 
     return 0;
 }
 
 /*
  * This function compares two trees and calls the provided callback for
  * every changed/new/deleted item it finds.
  * If shared tree blocks are encountered, whole subtrees are skipped, making
  * the compare pretty fast on snapshotted subvolumes.
  *
  * This currently works on commit roots only. As commit roots are read only,
  * we don't do any locking. The commit roots are protected with transactions.
  * Transactions are ended and rejoined when a commit is tried in between.
  *
  * This function checks for modifications done to the trees while comparing.
  * If it detects a change, it aborts immediately.
  */
 static int btrfs_compare_trees(struct btrfs_root *left_root,
             struct btrfs_root *right_root, struct send_ctx *sctx)
 {
     struct btrfs_fs_info *fs_info = left_root->fs_info;
     int ret;
     int cmp;
     struct btrfs_path *left_path = NULL;
     struct btrfs_path *right_path = NULL;
     struct btrfs_key left_key;
     struct btrfs_key right_key;
     char *tmp_buf = NULL;
     int left_root_level;
     int right_root_level;
     int left_level;
     int right_level;
     int left_end_reached = 0;
     int right_end_reached = 0;
     int advance_left = 0;
     int advance_right = 0;
     u64 left_blockptr;
     u64 right_blockptr;
     u64 left_gen;
     u64 right_gen;
     u64 reada_min_gen;
 
     left_path = btrfs_alloc_path();
     if (!left_path) {
         ret = -ENOMEM;
         goto out;
     }
     right_path = btrfs_alloc_path();
     if (!right_path) {
         ret = -ENOMEM;
         goto out;
     }
 
     tmp_buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
     if (!tmp_buf) {
         ret = -ENOMEM;
         goto out;
     }
 
     left_path->search_commit_root = 1;
     left_path->skip_locking = 1;
     right_path->search_commit_root = 1;
     right_path->skip_locking = 1;
 
     /*
      * Strategy: Go to the first items of both trees. Then do
      *
      * If both trees are at level 0
      *   Compare keys of current items
      *     If left < right treat left item as new, advance left tree
      *       and repeat
      *     If left > right treat right item as deleted, advance right tree
      *       and repeat
      *     If left == right do deep compare of items, treat as changed if
      *       needed, advance both trees and repeat
      * If both trees are at the same level but not at level 0
      *   Compare keys of current nodes/leafs
      *     If left < right advance left tree and repeat
      *     If left > right advance right tree and repeat
      *     If left == right compare blockptrs of the next nodes/leafs
      *       If they match advance both trees but stay at the same level
      *         and repeat
      *       If they don't match advance both trees while allowing to go
      *         deeper and repeat
      * If tree levels are different
      *   Advance the tree that needs it and repeat
      *
      * Advancing a tree means:
      *   If we are at level 0, try to go to the next slot. If that's not
      *   possible, go one level up and repeat. Stop when we found a level
      *   where we could go to the next slot. We may at this point be on a
      *   node or a leaf.
      *
      *   If we are not at level 0 and not on shared tree blocks, go one
      *   level deeper.
      *
      *   If we are not at level 0 and on shared tree blocks, go one slot to
      *   the right if possible or go up and right.
      */
 
     down_read(&fs_info->commit_root_sem);
     left_level = btrfs_header_level(left_root->commit_root);
     left_root_level = left_level;
     /*
      * We clone the root node of the send and parent roots to prevent races
      * with snapshot creation of these roots. Snapshot creation COWs the
      * root node of a tree, so after the transaction is committed the old
      * extent can be reallocated while this send operation is still ongoing.
      * So we clone them, under the commit root semaphore, to be race free.
      */
     left_path->nodes[left_level] =
             btrfs_clone_extent_buffer(left_root->commit_root);
     if (!left_path->nodes[left_level]) {
         ret = -ENOMEM;
         goto out_unlock;
     }
 
     right_level = btrfs_header_level(right_root->commit_root);
     right_root_level = right_level;
     right_path->nodes[right_level] =
             btrfs_clone_extent_buffer(right_root->commit_root);
     if (!right_path->nodes[right_level]) {
         ret = -ENOMEM;
         goto out_unlock;
     }
     /*
      * Our right root is the parent root, while the left root is the "send"
      * root. We know that all new nodes/leaves in the left root must have
      * a generation greater than the right root's generation, so we trigger
      * readahead for those nodes and leaves of the left root, as we know we
      * will need to read them at some point.
      */
     reada_min_gen = btrfs_header_generation(right_root->commit_root);
 
     if (left_level == 0)
         btrfs_item_key_to_cpu(left_path->nodes[left_level],
                 &left_key, left_path->slots[left_level]);
     else
         btrfs_node_key_to_cpu(left_path->nodes[left_level],
                 &left_key, left_path->slots[left_level]);
     if (right_level == 0)
         btrfs_item_key_to_cpu(right_path->nodes[right_level],
                 &right_key, right_path->slots[right_level]);
     else
         btrfs_node_key_to_cpu(right_path->nodes[right_level],
                 &right_key, right_path->slots[right_level]);
 
     sctx->last_reloc_trans = fs_info->last_reloc_trans;
 
     while (1) {
         if (need_resched() ||
             rwsem_is_contended(&fs_info->commit_root_sem)) {
             up_read(&fs_info->commit_root_sem);
             cond_resched();
             down_read(&fs_info->commit_root_sem);
         }
 
         if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
             ret = restart_after_relocation(left_path, right_path,
                                &left_key, &right_key,
                                left_level, right_level,
                                sctx);
             if (ret < 0)
                 goto out_unlock;
             sctx->last_reloc_trans = fs_info->last_reloc_trans;
         }
 
         if (advance_left && !left_end_reached) {
             ret = tree_advance(left_path, &left_level,
                     left_root_level,
                     advance_left != ADVANCE_ONLY_NEXT,
                     &left_key, reada_min_gen);
             if (ret == -1)
                 left_end_reached = ADVANCE;
             else if (ret < 0)
                 goto out_unlock;
             advance_left = 0;
         }
         if (advance_right && !right_end_reached) {
             ret = tree_advance(right_path, &right_level,
                     right_root_level,
                     advance_right != ADVANCE_ONLY_NEXT,
                     &right_key, reada_min_gen);
             if (ret == -1)
                 right_end_reached = ADVANCE;
             else if (ret < 0)
                 goto out_unlock;
             advance_right = 0;
         }
 
         if (left_end_reached && right_end_reached) {
             ret = 0;
             goto out_unlock;
         } else if (left_end_reached) {
             if (right_level == 0) {
                 up_read(&fs_info->commit_root_sem);
                 ret = changed_cb(left_path, right_path,
                         &right_key,
                         BTRFS_COMPARE_TREE_DELETED,
                         sctx);
                 if (ret < 0)
                     goto out;
                 down_read(&fs_info->commit_root_sem);
             }
             advance_right = ADVANCE;
             continue;
         } else if (right_end_reached) {
             if (left_level == 0) {
                 up_read(&fs_info->commit_root_sem);
                 ret = changed_cb(left_path, right_path,
                         &left_key,
                         BTRFS_COMPARE_TREE_NEW,
                         sctx);
                 if (ret < 0)
                     goto out;
                 down_read(&fs_info->commit_root_sem);
             }
             advance_left = ADVANCE;
             continue;
         }
 
         if (left_level == 0 && right_level == 0) {
             up_read(&fs_info->commit_root_sem);
             cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
             if (cmp < 0) {
                 ret = changed_cb(left_path, right_path,
                         &left_key,
                         BTRFS_COMPARE_TREE_NEW,
                         sctx);
                 advance_left = ADVANCE;
             } else if (cmp > 0) {
                 ret = changed_cb(left_path, right_path,
                         &right_key,
                         BTRFS_COMPARE_TREE_DELETED,
                         sctx);
                 advance_right = ADVANCE;
             } else {
                 enum btrfs_compare_tree_result result;
 
                 WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
                 ret = tree_compare_item(left_path, right_path,
                             tmp_buf);
                 if (ret)
                     result = BTRFS_COMPARE_TREE_CHANGED;
                 else
                     result = BTRFS_COMPARE_TREE_SAME;
                 ret = changed_cb(left_path, right_path,
                          &left_key, result, sctx);
                 advance_left = ADVANCE;
                 advance_right = ADVANCE;
             }
 
             if (ret < 0)
                 goto out;
             down_read(&fs_info->commit_root_sem);
         } else if (left_level == right_level) {
             cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
             if (cmp < 0) {
                 advance_left = ADVANCE;
             } else if (cmp > 0) {
                 advance_right = ADVANCE;
             } else {
                 left_blockptr = btrfs_node_blockptr(
                         left_path->nodes[left_level],
                         left_path->slots[left_level]);
                 right_blockptr = btrfs_node_blockptr(
                         right_path->nodes[right_level],
                         right_path->slots[right_level]);
                 left_gen = btrfs_node_ptr_generation(
                         left_path->nodes[left_level],
                         left_path->slots[left_level]);
                 right_gen = btrfs_node_ptr_generation(
                         right_path->nodes[right_level],
                         right_path->slots[right_level]);
                 if (left_blockptr == right_blockptr &&
                     left_gen == right_gen) {
                     /*
                      * As we're on a shared block, don't
                      * allow to go deeper.
                      */
                     advance_left = ADVANCE_ONLY_NEXT;
                     advance_right = ADVANCE_ONLY_NEXT;
                 } else {
                     advance_left = ADVANCE;
                     advance_right = ADVANCE;
                 }
             }
         } else if (left_level < right_level) {
             advance_right = ADVANCE;
         } else {
             advance_left = ADVANCE;
         }
     }
 
 out_unlock:
     up_read(&fs_info->commit_root_sem);
 out:
     btrfs_free_path(left_path);
     btrfs_free_path(right_path);
     kvfree(tmp_buf);
     return ret;
 }
 
 static int send_subvol(struct send_ctx *sctx)
 {
     int ret;
 
     if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_STREAM_HEADER)) {
         ret = send_header(sctx);
         if (ret < 0)
             goto out;
     }
 
     ret = send_subvol_begin(sctx);
     if (ret < 0)
         goto out;
 
     if (sctx->parent_root) {
         ret = btrfs_compare_trees(sctx->send_root, sctx->parent_root, sctx);
         if (ret < 0)
             goto out;
         ret = finish_inode_if_needed(sctx, 1);
         if (ret < 0)
             goto out;
     } else {
         ret = full_send_tree(sctx);
         if (ret < 0)
             goto out;
     }
 
 out:
     free_recorded_refs(sctx);
     return ret;
 }
 
 /*
  * If orphan cleanup did remove any orphans from a root, it means the tree
  * was modified and therefore the commit root is not the same as the current
  * root anymore. This is a problem, because send uses the commit root and
  * therefore can see inode items that don't exist in the current root anymore,
  * and for example make calls to btrfs_iget, which will do tree lookups based
  * on the current root and not on the commit root. Those lookups will fail,
  * returning a -ESTALE error, and making send fail with that error. So make
  * sure a send does not see any orphans we have just removed, and that it will
  * see the same inodes regardless of whether a transaction commit happened
  * before it started (meaning that the commit root will be the same as the
  * current root) or not.
  */
 static int ensure_commit_roots_uptodate(struct send_ctx *sctx)
 {
     int i;
     struct btrfs_trans_handle *trans = NULL;
 
 again:
     if (sctx->parent_root &&
         sctx->parent_root->node != sctx->parent_root->commit_root)
         goto commit_trans;
 
     for (i = 0; i < sctx->clone_roots_cnt; i++)
         if (sctx->clone_roots[i].root->node !=
             sctx->clone_roots[i].root->commit_root)
             goto commit_trans;
 
     if (trans)
         return btrfs_end_transaction(trans);
 
     return 0;
 
 commit_trans:
     /* Use any root, all fs roots will get their commit roots updated. */
     if (!trans) {
         trans = btrfs_join_transaction(sctx->send_root);
         if (IS_ERR(trans))
             return PTR_ERR(trans);
         goto again;
     }
 
     return btrfs_commit_transaction(trans);
 }
 
 /*
  * Make sure any existing dellaloc is flushed for any root used by a send
  * operation so that we do not miss any data and we do not race with writeback
  * finishing and changing a tree while send is using the tree. This could
  * happen if a subvolume is in RW mode, has delalloc, is turned to RO mode and
  * a send operation then uses the subvolume.
  * After flushing delalloc ensure_commit_roots_uptodate() must be called.
  */
 static int flush_delalloc_roots(struct send_ctx *sctx)
 {
     struct btrfs_root *root = sctx->parent_root;
     int ret;
     int i;
 
     if (root) {
         ret = btrfs_start_delalloc_snapshot(root, false);
         if (ret)
             return ret;
         btrfs_wait_ordered_extents(root, U64_MAX, 0, U64_MAX);
     }
 
     for (i = 0; i < sctx->clone_roots_cnt; i++) {
         root = sctx->clone_roots[i].root;
         ret = btrfs_start_delalloc_snapshot(root, false);
         if (ret)
             return ret;
         btrfs_wait_ordered_extents(root, U64_MAX, 0, U64_MAX);
     }
 
     return 0;
 }
 
 static void btrfs_root_dec_send_in_progress(struct btrfs_root* root)
 {
     spin_lock(&root->root_item_lock);
     root->send_in_progress--;
     /*
      * Not much left to do, we don't know why it's unbalanced and
      * can't blindly reset it to 0.
      */
     if (root->send_in_progress < 0)
         btrfs_err(root->fs_info,
               "send_in_progress unbalanced %d root %llu",
               root->send_in_progress, root->root_key.objectid);
     spin_unlock(&root->root_item_lock);
 }
 
 static void dedupe_in_progress_warn(const struct btrfs_root *root)
 {
     btrfs_warn_rl(root->fs_info,
 "cannot use root %llu for send while deduplications on it are in progress (%d in progress)",
               root->root_key.objectid, root->dedupe_in_progress);
 }
 
 long btrfs_ioctl_send(struct inode *inode, struct btrfs_ioctl_send_args *arg)
 {
     int ret = 0;
     struct btrfs_root *send_root = BTRFS_I(inode)->root;
     struct btrfs_fs_info *fs_info = send_root->fs_info;
     struct btrfs_root *clone_root;
     struct send_ctx *sctx = NULL;
     u32 i;
     u64 *clone_sources_tmp = NULL;
     int clone_sources_to_rollback = 0;
     size_t alloc_size;
     int sort_clone_roots = 0;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     /*
      * The subvolume must remain read-only during send, protect against
      * making it RW. This also protects against deletion.
      */
     spin_lock(&send_root->root_item_lock);
     if (btrfs_root_readonly(send_root) && send_root->dedupe_in_progress) {
         dedupe_in_progress_warn(send_root);
         spin_unlock(&send_root->root_item_lock);
         return -EAGAIN;
     }
     send_root->send_in_progress++;
     spin_unlock(&send_root->root_item_lock);
 
     /*
      * Userspace tools do the checks and warn the user if it's
      * not RO.
      */
     if (!btrfs_root_readonly(send_root)) {
         ret = -EPERM;
         goto out;
     }
 
     /*
      * Check that we don't overflow at later allocations, we request
      * clone_sources_count + 1 items, and compare to unsigned long inside
      * access_ok.
      */
     if (arg->clone_sources_count >
         ULONG_MAX / sizeof(struct clone_root) - 1) {
         ret = -EINVAL;
         goto out;
     }
 
     if (arg->flags & ~BTRFS_SEND_FLAG_MASK) {
         ret = -EINVAL;
         goto out;
     }
 
     sctx = kzalloc(sizeof(struct send_ctx), GFP_KERNEL);
     if (!sctx) {
         ret = -ENOMEM;
         goto out;
     }
 
     INIT_LIST_HEAD(&sctx->new_refs);
     INIT_LIST_HEAD(&sctx->deleted_refs);
     INIT_RADIX_TREE(&sctx->name_cache, GFP_KERNEL);
     INIT_LIST_HEAD(&sctx->name_cache_list);
 
     sctx->flags = arg->flags;
 
     if (arg->flags & BTRFS_SEND_FLAG_VERSION) {
         if (arg->version > BTRFS_SEND_STREAM_VERSION) {
             ret = -EPROTO;
             goto out;
         }
         /* Zero means "use the highest version" */
         sctx->proto = arg->version ?: BTRFS_SEND_STREAM_VERSION;
     } else {
         sctx->proto = 1;
     }
     if ((arg->flags & BTRFS_SEND_FLAG_COMPRESSED) && sctx->proto < 2) {
         ret = -EINVAL;
         goto out;
     }
 
     sctx->send_filp = fget(arg->send_fd);
     if (!sctx->send_filp) {
         ret = -EBADF;
         goto out;
     }
 
     sctx->send_root = send_root;
     /*
      * Unlikely but possible, if the subvolume is marked for deletion but
      * is slow to remove the directory entry, send can still be started
      */
     if (btrfs_root_dead(sctx->send_root)) {
         ret = -EPERM;
         goto out;
     }
 
     sctx->clone_roots_cnt = arg->clone_sources_count;
 
     if (sctx->proto >= 2) {
         u32 send_buf_num_pages;
 
         sctx->send_max_size = ALIGN(SZ_16K + BTRFS_MAX_COMPRESSED, PAGE_SIZE);
         sctx->send_buf = vmalloc(sctx->send_max_size);
         if (!sctx->send_buf) {
             ret = -ENOMEM;
             goto out;
         }
         send_buf_num_pages = sctx->send_max_size >> PAGE_SHIFT;
         sctx->send_buf_pages = kcalloc(send_buf_num_pages,
                            sizeof(*sctx->send_buf_pages),
                            GFP_KERNEL);
         if (!sctx->send_buf_pages) {
             ret = -ENOMEM;
             goto out;
         }
         for (i = 0; i < send_buf_num_pages; i++) {
             sctx->send_buf_pages[i] =
                 vmalloc_to_page(sctx->send_buf + (i << PAGE_SHIFT));
         }
     } else {
         sctx->send_max_size = BTRFS_SEND_BUF_SIZE_V1;
         sctx->send_buf = kvmalloc(sctx->send_max_size, GFP_KERNEL);
     }
     if (!sctx->send_buf) {
         ret = -ENOMEM;
         goto out;
     }
 
     sctx->pending_dir_moves = RB_ROOT;
     sctx->waiting_dir_moves = RB_ROOT;
     sctx->orphan_dirs = RB_ROOT;
     sctx->rbtree_new_refs = RB_ROOT;
     sctx->rbtree_deleted_refs = RB_ROOT;
 
     sctx->clone_roots = kvcalloc(sizeof(*sctx->clone_roots),
                      arg->clone_sources_count + 1,
                      GFP_KERNEL);
     if (!sctx->clone_roots) {
         ret = -ENOMEM;
         goto out;
     }
 
     alloc_size = array_size(sizeof(*arg->clone_sources),
                 arg->clone_sources_count);
 
     if (arg->clone_sources_count) {
         clone_sources_tmp = kvmalloc(alloc_size, GFP_KERNEL);
         if (!clone_sources_tmp) {
             ret = -ENOMEM;
             goto out;
         }
 
         ret = copy_from_user(clone_sources_tmp, arg->clone_sources,
                 alloc_size);
         if (ret) {
             ret = -EFAULT;
             goto out;
         }
 
         for (i = 0; i < arg->clone_sources_count; i++) {
             clone_root = btrfs_get_fs_root(fs_info,
                         clone_sources_tmp[i], true);
             if (IS_ERR(clone_root)) {
                 ret = PTR_ERR(clone_root);
                 goto out;
             }
             spin_lock(&clone_root->root_item_lock);
             if (!btrfs_root_readonly(clone_root) ||
                 btrfs_root_dead(clone_root)) {
                 spin_unlock(&clone_root->root_item_lock);
                 btrfs_put_root(clone_root);
                 ret = -EPERM;
                 goto out;
             }
             if (clone_root->dedupe_in_progress) {
                 dedupe_in_progress_warn(clone_root);
                 spin_unlock(&clone_root->root_item_lock);
                 btrfs_put_root(clone_root);
                 ret = -EAGAIN;
                 goto out;
             }
             clone_root->send_in_progress++;
             spin_unlock(&clone_root->root_item_lock);
 
             sctx->clone_roots[i].root = clone_root;
             clone_sources_to_rollback = i + 1;
         }
         kvfree(clone_sources_tmp);
         clone_sources_tmp = NULL;
     }
 
     if (arg->parent_root) {
         sctx->parent_root = btrfs_get_fs_root(fs_info, arg->parent_root,
                               true);
         if (IS_ERR(sctx->parent_root)) {
             ret = PTR_ERR(sctx->parent_root);
             goto out;
         }
 
         spin_lock(&sctx->parent_root->root_item_lock);
         sctx->parent_root->send_in_progress++;
         if (!btrfs_root_readonly(sctx->parent_root) ||
                 btrfs_root_dead(sctx->parent_root)) {
             spin_unlock(&sctx->parent_root->root_item_lock);
             ret = -EPERM;
             goto out;
         }
         if (sctx->parent_root->dedupe_in_progress) {
             dedupe_in_progress_warn(sctx->parent_root);
             spin_unlock(&sctx->parent_root->root_item_lock);
             ret = -EAGAIN;
             goto out;
         }
         spin_unlock(&sctx->parent_root->root_item_lock);
     }
 
     /*
      * Clones from send_root are allowed, but only if the clone source
      * is behind the current send position. This is checked while searching
      * for possible clone sources.
      */
     sctx->clone_roots[sctx->clone_roots_cnt++].root =
         btrfs_grab_root(sctx->send_root);
 
     /* We do a bsearch later */
     sort(sctx->clone_roots, sctx->clone_roots_cnt,
             sizeof(*sctx->clone_roots), __clone_root_cmp_sort,
             NULL);
     sort_clone_roots = 1;
 
     ret = flush_delalloc_roots(sctx);
     if (ret)
         goto out;
 
     ret = ensure_commit_roots_uptodate(sctx);
     if (ret)
         goto out;
 
     ret = send_subvol(sctx);
     if (ret < 0)
         goto out;
 
     if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_END_CMD)) {
         ret = begin_cmd(sctx, BTRFS_SEND_C_END);
         if (ret < 0)
             goto out;
         ret = send_cmd(sctx);
         if (ret < 0)
             goto out;
     }
 
 out:
     WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->pending_dir_moves));
     while (sctx && !RB_EMPTY_ROOT(&sctx->pending_dir_moves)) {
         struct rb_node *n;
         struct pending_dir_move *pm;
 
         n = rb_first(&sctx->pending_dir_moves);
         pm = rb_entry(n, struct pending_dir_move, node);
         while (!list_empty(&pm->list)) {
             struct pending_dir_move *pm2;
 
             pm2 = list_first_entry(&pm->list,
                            struct pending_dir_move, list);
             free_pending_move(sctx, pm2);
         }
         free_pending_move(sctx, pm);
     }
 
     WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves));
     while (sctx && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves)) {
         struct rb_node *n;
         struct waiting_dir_move *dm;
 
         n = rb_first(&sctx->waiting_dir_moves);
         dm = rb_entry(n, struct waiting_dir_move, node);
         rb_erase(&dm->node, &sctx->waiting_dir_moves);
         kfree(dm);
     }
 
     WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->orphan_dirs));
     while (sctx && !RB_EMPTY_ROOT(&sctx->orphan_dirs)) {
         struct rb_node *n;
         struct orphan_dir_info *odi;
 
         n = rb_first(&sctx->orphan_dirs);
         odi = rb_entry(n, struct orphan_dir_info, node);
         free_orphan_dir_info(sctx, odi);
     }
 
     if (sort_clone_roots) {
         for (i = 0; i < sctx->clone_roots_cnt; i++) {
             btrfs_root_dec_send_in_progress(
                     sctx->clone_roots[i].root);
             btrfs_put_root(sctx->clone_roots[i].root);
         }
     } else {
         for (i = 0; sctx && i < clone_sources_to_rollback; i++) {
             btrfs_root_dec_send_in_progress(
                     sctx->clone_roots[i].root);
             btrfs_put_root(sctx->clone_roots[i].root);
         }
 
         btrfs_root_dec_send_in_progress(send_root);
     }
     if (sctx && !IS_ERR_OR_NULL(sctx->parent_root)) {
         btrfs_root_dec_send_in_progress(sctx->parent_root);
         btrfs_put_root(sctx->parent_root);
     }
 
     kvfree(clone_sources_tmp);
 
     if (sctx) {
         if (sctx->send_filp)
             fput(sctx->send_filp);
 
         kvfree(sctx->clone_roots);
         kfree(sctx->send_buf_pages);
         kvfree(sctx->send_buf);
 
         name_cache_free(sctx);
 
         close_current_inode(sctx);
 
         kfree(sctx);
     }
 
     return ret;
 }