OSCL-LXR linux-6.0.1/​fs/​btrfs/​ioctl.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) 2007 Oracle.  All rights reserved.
  */
 
 #include <linux/kernel.h>
 #include <linux/bio.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/fsnotify.h>
 #include <linux/pagemap.h>
 #include <linux/highmem.h>
 #include <linux/time.h>
 #include <linux/string.h>
 #include <linux/backing-dev.h>
 #include <linux/mount.h>
 #include <linux/namei.h>
 #include <linux/writeback.h>
 #include <linux/compat.h>
 #include <linux/security.h>
 #include <linux/xattr.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/blkdev.h>
 #include <linux/uuid.h>
 #include <linux/btrfs.h>
 #include <linux/uaccess.h>
 #include <linux/iversion.h>
 #include <linux/fileattr.h>
 #include <linux/fsverity.h>
 #include <linux/sched/xacct.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "export.h"
 #include "transaction.h"
 #include "btrfs_inode.h"
 #include "print-tree.h"
 #include "volumes.h"
 #include "locking.h"
 #include "backref.h"
 #include "rcu-string.h"
 #include "send.h"
 #include "dev-replace.h"
 #include "props.h"
 #include "sysfs.h"
 #include "qgroup.h"
 #include "tree-log.h"
 #include "compression.h"
 #include "space-info.h"
 #include "delalloc-space.h"
 #include "block-group.h"
 #include "subpage.h"
 
 #ifdef CONFIG_64BIT
 /* If we have a 32-bit userspace and 64-bit kernel, then the UAPI
  * structures are incorrect, as the timespec structure from userspace
  * is 4 bytes too small. We define these alternatives here to teach
  * the kernel about the 32-bit struct packing.
  */
 struct btrfs_ioctl_timespec_32 {
     __u64 sec;
     __u32 nsec;
 } __attribute__ ((__packed__));
 
 struct btrfs_ioctl_received_subvol_args_32 {
     char    uuid[BTRFS_UUID_SIZE];  /* in */
     __u64   stransid;       /* in */
     __u64   rtransid;       /* out */
     struct btrfs_ioctl_timespec_32 stime; /* in */
     struct btrfs_ioctl_timespec_32 rtime; /* out */
     __u64   flags;          /* in */
     __u64   reserved[16];       /* in */
 } __attribute__ ((__packed__));
 
 #define BTRFS_IOC_SET_RECEIVED_SUBVOL_32 _IOWR(BTRFS_IOCTL_MAGIC, 37, \
                 struct btrfs_ioctl_received_subvol_args_32)
 #endif
 
 #if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
 struct btrfs_ioctl_send_args_32 {
     __s64 send_fd;          /* in */
     __u64 clone_sources_count;  /* in */
     compat_uptr_t clone_sources;    /* in */
     __u64 parent_root;      /* in */
     __u64 flags;            /* in */
     __u32 version;          /* in */
     __u8  reserved[28];     /* in */
 } __attribute__ ((__packed__));
 
 #define BTRFS_IOC_SEND_32 _IOW(BTRFS_IOCTL_MAGIC, 38, \
                    struct btrfs_ioctl_send_args_32)
 
 struct btrfs_ioctl_encoded_io_args_32 {
     compat_uptr_t iov;
     compat_ulong_t iovcnt;
     __s64 offset;
     __u64 flags;
     __u64 len;
     __u64 unencoded_len;
     __u64 unencoded_offset;
     __u32 compression;
     __u32 encryption;
     __u8 reserved[64];
 };
 
 #define BTRFS_IOC_ENCODED_READ_32 _IOR(BTRFS_IOCTL_MAGIC, 64, \
                        struct btrfs_ioctl_encoded_io_args_32)
 #define BTRFS_IOC_ENCODED_WRITE_32 _IOW(BTRFS_IOCTL_MAGIC, 64, \
                     struct btrfs_ioctl_encoded_io_args_32)
 #endif
 
 /* Mask out flags that are inappropriate for the given type of inode. */
 static unsigned int btrfs_mask_fsflags_for_type(struct inode *inode,
         unsigned int flags)
 {
     if (S_ISDIR(inode->i_mode))
         return flags;
     else if (S_ISREG(inode->i_mode))
         return flags & ~FS_DIRSYNC_FL;
     else
         return flags & (FS_NODUMP_FL | FS_NOATIME_FL);
 }
 
 /*
  * Export internal inode flags to the format expected by the FS_IOC_GETFLAGS
  * ioctl.
  */
 static unsigned int btrfs_inode_flags_to_fsflags(struct btrfs_inode *binode)
 {
     unsigned int iflags = 0;
     u32 flags = binode->flags;
     u32 ro_flags = binode->ro_flags;
 
     if (flags & BTRFS_INODE_SYNC)
         iflags |= FS_SYNC_FL;
     if (flags & BTRFS_INODE_IMMUTABLE)
         iflags |= FS_IMMUTABLE_FL;
     if (flags & BTRFS_INODE_APPEND)
         iflags |= FS_APPEND_FL;
     if (flags & BTRFS_INODE_NODUMP)
         iflags |= FS_NODUMP_FL;
     if (flags & BTRFS_INODE_NOATIME)
         iflags |= FS_NOATIME_FL;
     if (flags & BTRFS_INODE_DIRSYNC)
         iflags |= FS_DIRSYNC_FL;
     if (flags & BTRFS_INODE_NODATACOW)
         iflags |= FS_NOCOW_FL;
     if (ro_flags & BTRFS_INODE_RO_VERITY)
         iflags |= FS_VERITY_FL;
 
     if (flags & BTRFS_INODE_NOCOMPRESS)
         iflags |= FS_NOCOMP_FL;
     else if (flags & BTRFS_INODE_COMPRESS)
         iflags |= FS_COMPR_FL;
 
     return iflags;
 }
 
 /*
  * Update inode->i_flags based on the btrfs internal flags.
  */
 void btrfs_sync_inode_flags_to_i_flags(struct inode *inode)
 {
     struct btrfs_inode *binode = BTRFS_I(inode);
     unsigned int new_fl = 0;
 
     if (binode->flags & BTRFS_INODE_SYNC)
         new_fl |= S_SYNC;
     if (binode->flags & BTRFS_INODE_IMMUTABLE)
         new_fl |= S_IMMUTABLE;
     if (binode->flags & BTRFS_INODE_APPEND)
         new_fl |= S_APPEND;
     if (binode->flags & BTRFS_INODE_NOATIME)
         new_fl |= S_NOATIME;
     if (binode->flags & BTRFS_INODE_DIRSYNC)
         new_fl |= S_DIRSYNC;
     if (binode->ro_flags & BTRFS_INODE_RO_VERITY)
         new_fl |= S_VERITY;
 
     set_mask_bits(&inode->i_flags,
               S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC |
               S_VERITY, new_fl);
 }
 
 /*
  * Check if @flags are a supported and valid set of FS_*_FL flags and that
  * the old and new flags are not conflicting
  */
 static int check_fsflags(unsigned int old_flags, unsigned int flags)
 {
     if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
               FS_NOATIME_FL | FS_NODUMP_FL | \
               FS_SYNC_FL | FS_DIRSYNC_FL | \
               FS_NOCOMP_FL | FS_COMPR_FL |
               FS_NOCOW_FL))
         return -EOPNOTSUPP;
 
     /* COMPR and NOCOMP on new/old are valid */
     if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
         return -EINVAL;
 
     if ((flags & FS_COMPR_FL) && (flags & FS_NOCOW_FL))
         return -EINVAL;
 
     /* NOCOW and compression options are mutually exclusive */
     if ((old_flags & FS_NOCOW_FL) && (flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
         return -EINVAL;
     if ((flags & FS_NOCOW_FL) && (old_flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
         return -EINVAL;
 
     return 0;
 }
 
 static int check_fsflags_compatible(struct btrfs_fs_info *fs_info,
                     unsigned int flags)
 {
     if (btrfs_is_zoned(fs_info) && (flags & FS_NOCOW_FL))
         return -EPERM;
 
     return 0;
 }
 
 /*
  * Set flags/xflags from the internal inode flags. The remaining items of
  * fsxattr are zeroed.
  */
 int btrfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 {
     struct btrfs_inode *binode = BTRFS_I(d_inode(dentry));
 
     fileattr_fill_flags(fa, btrfs_inode_flags_to_fsflags(binode));
     return 0;
 }
 
 int btrfs_fileattr_set(struct user_namespace *mnt_userns,
                struct dentry *dentry, struct fileattr *fa)
 {
     struct inode *inode = d_inode(dentry);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_inode *binode = BTRFS_I(inode);
     struct btrfs_root *root = binode->root;
     struct btrfs_trans_handle *trans;
     unsigned int fsflags, old_fsflags;
     int ret;
     const char *comp = NULL;
     u32 binode_flags;
 
     if (btrfs_root_readonly(root))
         return -EROFS;
 
     if (fileattr_has_fsx(fa))
         return -EOPNOTSUPP;
 
     fsflags = btrfs_mask_fsflags_for_type(inode, fa->flags);
     old_fsflags = btrfs_inode_flags_to_fsflags(binode);
     ret = check_fsflags(old_fsflags, fsflags);
     if (ret)
         return ret;
 
     ret = check_fsflags_compatible(fs_info, fsflags);
     if (ret)
         return ret;
 
     binode_flags = binode->flags;
     if (fsflags & FS_SYNC_FL)
         binode_flags |= BTRFS_INODE_SYNC;
     else
         binode_flags &= ~BTRFS_INODE_SYNC;
     if (fsflags & FS_IMMUTABLE_FL)
         binode_flags |= BTRFS_INODE_IMMUTABLE;
     else
         binode_flags &= ~BTRFS_INODE_IMMUTABLE;
     if (fsflags & FS_APPEND_FL)
         binode_flags |= BTRFS_INODE_APPEND;
     else
         binode_flags &= ~BTRFS_INODE_APPEND;
     if (fsflags & FS_NODUMP_FL)
         binode_flags |= BTRFS_INODE_NODUMP;
     else
         binode_flags &= ~BTRFS_INODE_NODUMP;
     if (fsflags & FS_NOATIME_FL)
         binode_flags |= BTRFS_INODE_NOATIME;
     else
         binode_flags &= ~BTRFS_INODE_NOATIME;
 
     /* If coming from FS_IOC_FSSETXATTR then skip unconverted flags */
     if (!fa->flags_valid) {
         /* 1 item for the inode */
         trans = btrfs_start_transaction(root, 1);
         if (IS_ERR(trans))
             return PTR_ERR(trans);
         goto update_flags;
     }
 
     if (fsflags & FS_DIRSYNC_FL)
         binode_flags |= BTRFS_INODE_DIRSYNC;
     else
         binode_flags &= ~BTRFS_INODE_DIRSYNC;
     if (fsflags & FS_NOCOW_FL) {
         if (S_ISREG(inode->i_mode)) {
             /*
              * It's safe to turn csums off here, no extents exist.
              * Otherwise we want the flag to reflect the real COW
              * status of the file and will not set it.
              */
             if (inode->i_size == 0)
                 binode_flags |= BTRFS_INODE_NODATACOW |
                         BTRFS_INODE_NODATASUM;
         } else {
             binode_flags |= BTRFS_INODE_NODATACOW;
         }
     } else {
         /*
          * Revert back under same assumptions as above
          */
         if (S_ISREG(inode->i_mode)) {
             if (inode->i_size == 0)
                 binode_flags &= ~(BTRFS_INODE_NODATACOW |
                           BTRFS_INODE_NODATASUM);
         } else {
             binode_flags &= ~BTRFS_INODE_NODATACOW;
         }
     }
 
     /*
      * The COMPRESS flag can only be changed by users, while the NOCOMPRESS
      * flag may be changed automatically if compression code won't make
      * things smaller.
      */
     if (fsflags & FS_NOCOMP_FL) {
         binode_flags &= ~BTRFS_INODE_COMPRESS;
         binode_flags |= BTRFS_INODE_NOCOMPRESS;
     } else if (fsflags & FS_COMPR_FL) {
 
         if (IS_SWAPFILE(inode))
             return -ETXTBSY;
 
         binode_flags |= BTRFS_INODE_COMPRESS;
         binode_flags &= ~BTRFS_INODE_NOCOMPRESS;
 
         comp = btrfs_compress_type2str(fs_info->compress_type);
         if (!comp || comp[0] == 0)
             comp = btrfs_compress_type2str(BTRFS_COMPRESS_ZLIB);
     } else {
         binode_flags &= ~(BTRFS_INODE_COMPRESS | BTRFS_INODE_NOCOMPRESS);
     }
 
     /*
      * 1 for inode item
      * 2 for properties
      */
     trans = btrfs_start_transaction(root, 3);
     if (IS_ERR(trans))
         return PTR_ERR(trans);
 
     if (comp) {
         ret = btrfs_set_prop(trans, inode, "btrfs.compression", comp,
                      strlen(comp), 0);
         if (ret) {
             btrfs_abort_transaction(trans, ret);
             goto out_end_trans;
         }
     } else {
         ret = btrfs_set_prop(trans, inode, "btrfs.compression", NULL,
                      0, 0);
         if (ret && ret != -ENODATA) {
             btrfs_abort_transaction(trans, ret);
             goto out_end_trans;
         }
     }
 
 update_flags:
     binode->flags = binode_flags;
     btrfs_sync_inode_flags_to_i_flags(inode);
     inode_inc_iversion(inode);
     inode->i_ctime = current_time(inode);
     ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
 
  out_end_trans:
     btrfs_end_transaction(trans);
     return ret;
 }
 
 /*
  * Start exclusive operation @type, return true on success
  */
 bool btrfs_exclop_start(struct btrfs_fs_info *fs_info,
             enum btrfs_exclusive_operation type)
 {
     bool ret = false;
 
     spin_lock(&fs_info->super_lock);
     if (fs_info->exclusive_operation == BTRFS_EXCLOP_NONE) {
         fs_info->exclusive_operation = type;
         ret = true;
     }
     spin_unlock(&fs_info->super_lock);
 
     return ret;
 }
 
 /*
  * Conditionally allow to enter the exclusive operation in case it's compatible
  * with the running one.  This must be paired with btrfs_exclop_start_unlock and
  * btrfs_exclop_finish.
  *
  * Compatibility:
  * - the same type is already running
  * - when trying to add a device and balance has been paused
  * - not BTRFS_EXCLOP_NONE - this is intentionally incompatible and the caller
  *   must check the condition first that would allow none -> @type
  */
 bool btrfs_exclop_start_try_lock(struct btrfs_fs_info *fs_info,
                  enum btrfs_exclusive_operation type)
 {
     spin_lock(&fs_info->super_lock);
     if (fs_info->exclusive_operation == type ||
         (fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED &&
          type == BTRFS_EXCLOP_DEV_ADD))
         return true;
 
     spin_unlock(&fs_info->super_lock);
     return false;
 }
 
 void btrfs_exclop_start_unlock(struct btrfs_fs_info *fs_info)
 {
     spin_unlock(&fs_info->super_lock);
 }
 
 void btrfs_exclop_finish(struct btrfs_fs_info *fs_info)
 {
     spin_lock(&fs_info->super_lock);
     WRITE_ONCE(fs_info->exclusive_operation, BTRFS_EXCLOP_NONE);
     spin_unlock(&fs_info->super_lock);
     sysfs_notify(&fs_info->fs_devices->fsid_kobj, NULL, "exclusive_operation");
 }
 
 void btrfs_exclop_balance(struct btrfs_fs_info *fs_info,
               enum btrfs_exclusive_operation op)
 {
     switch (op) {
     case BTRFS_EXCLOP_BALANCE_PAUSED:
         spin_lock(&fs_info->super_lock);
         ASSERT(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE ||
                fs_info->exclusive_operation == BTRFS_EXCLOP_DEV_ADD);
         fs_info->exclusive_operation = BTRFS_EXCLOP_BALANCE_PAUSED;
         spin_unlock(&fs_info->super_lock);
         break;
     case BTRFS_EXCLOP_BALANCE:
         spin_lock(&fs_info->super_lock);
         ASSERT(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED);
         fs_info->exclusive_operation = BTRFS_EXCLOP_BALANCE;
         spin_unlock(&fs_info->super_lock);
         break;
     default:
         btrfs_warn(fs_info,
             "invalid exclop balance operation %d requested", op);
     }
 }
 
 static int btrfs_ioctl_getversion(struct inode *inode, int __user *arg)
 {
     return put_user(inode->i_generation, arg);
 }
 
 static noinline int btrfs_ioctl_fitrim(struct btrfs_fs_info *fs_info,
                     void __user *arg)
 {
     struct btrfs_device *device;
     struct fstrim_range range;
     u64 minlen = ULLONG_MAX;
     u64 num_devices = 0;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     /*
      * btrfs_trim_block_group() depends on space cache, which is not
      * available in zoned filesystem. So, disallow fitrim on a zoned
      * filesystem for now.
      */
     if (btrfs_is_zoned(fs_info))
         return -EOPNOTSUPP;
 
     /*
      * If the fs is mounted with nologreplay, which requires it to be
      * mounted in RO mode as well, we can not allow discard on free space
      * inside block groups, because log trees refer to extents that are not
      * pinned in a block group's free space cache (pinning the extents is
      * precisely the first phase of replaying a log tree).
      */
     if (btrfs_test_opt(fs_info, NOLOGREPLAY))
         return -EROFS;
 
     rcu_read_lock();
     list_for_each_entry_rcu(device, &fs_info->fs_devices->devices,
                 dev_list) {
         if (!device->bdev || !bdev_max_discard_sectors(device->bdev))
             continue;
         num_devices++;
         minlen = min_t(u64, bdev_discard_granularity(device->bdev),
                     minlen);
     }
     rcu_read_unlock();
 
     if (!num_devices)
         return -EOPNOTSUPP;
     if (copy_from_user(&range, arg, sizeof(range)))
         return -EFAULT;
 
     /*
      * NOTE: Don't truncate the range using super->total_bytes.  Bytenr of
      * block group is in the logical address space, which can be any
      * sectorsize aligned bytenr in  the range [0, U64_MAX].
      */
     if (range.len < fs_info->sb->s_blocksize)
         return -EINVAL;
 
     range.minlen = max(range.minlen, minlen);
     ret = btrfs_trim_fs(fs_info, &range);
     if (ret < 0)
         return ret;
 
     if (copy_to_user(arg, &range, sizeof(range)))
         return -EFAULT;
 
     return 0;
 }
 
 int __pure btrfs_is_empty_uuid(u8 *uuid)
 {
     int i;
 
     for (i = 0; i < BTRFS_UUID_SIZE; i++) {
         if (uuid[i])
             return 0;
     }
     return 1;
 }
 
 /*
  * Calculate the number of transaction items to reserve for creating a subvolume
  * or snapshot, not including the inode, directory entries, or parent directory.
  */
 static unsigned int create_subvol_num_items(struct btrfs_qgroup_inherit *inherit)
 {
     /*
      * 1 to add root block
      * 1 to add root item
      * 1 to add root ref
      * 1 to add root backref
      * 1 to add UUID item
      * 1 to add qgroup info
      * 1 to add qgroup limit
      *
      * Ideally the last two would only be accounted if qgroups are enabled,
      * but that can change between now and the time we would insert them.
      */
     unsigned int num_items = 7;
 
     if (inherit) {
         /* 2 to add qgroup relations for each inherited qgroup */
         num_items += 2 * inherit->num_qgroups;
     }
     return num_items;
 }
 
 static noinline int create_subvol(struct user_namespace *mnt_userns,
                   struct inode *dir, struct dentry *dentry,
                   struct btrfs_qgroup_inherit *inherit)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
     struct btrfs_trans_handle *trans;
     struct btrfs_key key;
     struct btrfs_root_item *root_item;
     struct btrfs_inode_item *inode_item;
     struct extent_buffer *leaf;
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct btrfs_root *new_root;
     struct btrfs_block_rsv block_rsv;
     struct timespec64 cur_time = current_time(dir);
     struct btrfs_new_inode_args new_inode_args = {
         .dir = dir,
         .dentry = dentry,
         .subvol = true,
     };
     unsigned int trans_num_items;
     int ret;
     dev_t anon_dev;
     u64 objectid;
 
     root_item = kzalloc(sizeof(*root_item), GFP_KERNEL);
     if (!root_item)
         return -ENOMEM;
 
     ret = btrfs_get_free_objectid(fs_info->tree_root, &objectid);
     if (ret)
         goto out_root_item;
 
     /*
      * Don't create subvolume whose level is not zero. Or qgroup will be
      * screwed up since it assumes subvolume qgroup's level to be 0.
      */
     if (btrfs_qgroup_level(objectid)) {
         ret = -ENOSPC;
         goto out_root_item;
     }
 
     ret = get_anon_bdev(&anon_dev);
     if (ret < 0)
         goto out_root_item;
 
     new_inode_args.inode = btrfs_new_subvol_inode(mnt_userns, dir);
     if (!new_inode_args.inode) {
         ret = -ENOMEM;
         goto out_anon_dev;
     }
     ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
     if (ret)
         goto out_inode;
     trans_num_items += create_subvol_num_items(inherit);
 
     btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
     ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
                            trans_num_items, false);
     if (ret)
         goto out_new_inode_args;
 
     trans = btrfs_start_transaction(root, 0);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         btrfs_subvolume_release_metadata(root, &block_rsv);
         goto out_new_inode_args;
     }
     trans->block_rsv = &block_rsv;
     trans->bytes_reserved = block_rsv.size;
 
     ret = btrfs_qgroup_inherit(trans, 0, objectid, inherit);
     if (ret)
         goto out;
 
     leaf = btrfs_alloc_tree_block(trans, root, 0, objectid, NULL, 0, 0, 0,
                       BTRFS_NESTING_NORMAL);
     if (IS_ERR(leaf)) {
         ret = PTR_ERR(leaf);
         goto out;
     }
 
     btrfs_mark_buffer_dirty(leaf);
 
     inode_item = &root_item->inode;
     btrfs_set_stack_inode_generation(inode_item, 1);
     btrfs_set_stack_inode_size(inode_item, 3);
     btrfs_set_stack_inode_nlink(inode_item, 1);
     btrfs_set_stack_inode_nbytes(inode_item,
                      fs_info->nodesize);
     btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
 
     btrfs_set_root_flags(root_item, 0);
     btrfs_set_root_limit(root_item, 0);
     btrfs_set_stack_inode_flags(inode_item, BTRFS_INODE_ROOT_ITEM_INIT);
 
     btrfs_set_root_bytenr(root_item, leaf->start);
     btrfs_set_root_generation(root_item, trans->transid);
     btrfs_set_root_level(root_item, 0);
     btrfs_set_root_refs(root_item, 1);
     btrfs_set_root_used(root_item, leaf->len);
     btrfs_set_root_last_snapshot(root_item, 0);
 
     btrfs_set_root_generation_v2(root_item,
             btrfs_root_generation(root_item));
     generate_random_guid(root_item->uuid);
     btrfs_set_stack_timespec_sec(&root_item->otime, cur_time.tv_sec);
     btrfs_set_stack_timespec_nsec(&root_item->otime, cur_time.tv_nsec);
     root_item->ctime = root_item->otime;
     btrfs_set_root_ctransid(root_item, trans->transid);
     btrfs_set_root_otransid(root_item, trans->transid);
 
     btrfs_tree_unlock(leaf);
 
     btrfs_set_root_dirid(root_item, BTRFS_FIRST_FREE_OBJECTID);
 
     key.objectid = objectid;
     key.offset = 0;
     key.type = BTRFS_ROOT_ITEM_KEY;
     ret = btrfs_insert_root(trans, fs_info->tree_root, &key,
                 root_item);
     if (ret) {
         /*
          * Since we don't abort the transaction in this case, free the
          * tree block so that we don't leak space and leave the
          * filesystem in an inconsistent state (an extent item in the
          * extent tree with a backreference for a root that does not
          * exists).
          */
         btrfs_tree_lock(leaf);
         btrfs_clean_tree_block(leaf);
         btrfs_tree_unlock(leaf);
         btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
         free_extent_buffer(leaf);
         goto out;
     }
 
     free_extent_buffer(leaf);
     leaf = NULL;
 
     new_root = btrfs_get_new_fs_root(fs_info, objectid, anon_dev);
     if (IS_ERR(new_root)) {
         ret = PTR_ERR(new_root);
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
     /* anon_dev is owned by new_root now. */
     anon_dev = 0;
     BTRFS_I(new_inode_args.inode)->root = new_root;
     /* ... and new_root is owned by new_inode_args.inode now. */
 
     ret = btrfs_record_root_in_trans(trans, new_root);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     ret = btrfs_uuid_tree_add(trans, root_item->uuid,
                   BTRFS_UUID_KEY_SUBVOL, objectid);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     ret = btrfs_create_new_inode(trans, &new_inode_args);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     d_instantiate_new(dentry, new_inode_args.inode);
     new_inode_args.inode = NULL;
 
 out:
     trans->block_rsv = NULL;
     trans->bytes_reserved = 0;
     btrfs_subvolume_release_metadata(root, &block_rsv);
 
     if (ret)
         btrfs_end_transaction(trans);
     else
         ret = btrfs_commit_transaction(trans);
 out_new_inode_args:
     btrfs_new_inode_args_destroy(&new_inode_args);
 out_inode:
     iput(new_inode_args.inode);
 out_anon_dev:
     if (anon_dev)
         free_anon_bdev(anon_dev);
 out_root_item:
     kfree(root_item);
     return ret;
 }
 
 static int create_snapshot(struct btrfs_root *root, struct inode *dir,
                struct dentry *dentry, bool readonly,
                struct btrfs_qgroup_inherit *inherit)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
     struct inode *inode;
     struct btrfs_pending_snapshot *pending_snapshot;
     unsigned int trans_num_items;
     struct btrfs_trans_handle *trans;
     int ret;
 
     /* We do not support snapshotting right now. */
     if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
         btrfs_warn(fs_info,
                "extent tree v2 doesn't support snapshotting yet");
         return -EOPNOTSUPP;
     }
 
     if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
         return -EINVAL;
 
     if (atomic_read(&root->nr_swapfiles)) {
         btrfs_warn(fs_info,
                "cannot snapshot subvolume with active swapfile");
         return -ETXTBSY;
     }
 
     pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_KERNEL);
     if (!pending_snapshot)
         return -ENOMEM;
 
     ret = get_anon_bdev(&pending_snapshot->anon_dev);
     if (ret < 0)
         goto free_pending;
     pending_snapshot->root_item = kzalloc(sizeof(struct btrfs_root_item),
             GFP_KERNEL);
     pending_snapshot->path = btrfs_alloc_path();
     if (!pending_snapshot->root_item || !pending_snapshot->path) {
         ret = -ENOMEM;
         goto free_pending;
     }
 
     btrfs_init_block_rsv(&pending_snapshot->block_rsv,
                  BTRFS_BLOCK_RSV_TEMP);
     /*
      * 1 to add dir item
      * 1 to add dir index
      * 1 to update parent inode item
      */
     trans_num_items = create_subvol_num_items(inherit) + 3;
     ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
                            &pending_snapshot->block_rsv,
                            trans_num_items, false);
     if (ret)
         goto free_pending;
 
     pending_snapshot->dentry = dentry;
     pending_snapshot->root = root;
     pending_snapshot->readonly = readonly;
     pending_snapshot->dir = dir;
     pending_snapshot->inherit = inherit;
 
     trans = btrfs_start_transaction(root, 0);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto fail;
     }
 
     trans->pending_snapshot = pending_snapshot;
 
     ret = btrfs_commit_transaction(trans);
     if (ret)
         goto fail;
 
     ret = pending_snapshot->error;
     if (ret)
         goto fail;
 
     ret = btrfs_orphan_cleanup(pending_snapshot->snap);
     if (ret)
         goto fail;
 
     inode = btrfs_lookup_dentry(d_inode(dentry->d_parent), dentry);
     if (IS_ERR(inode)) {
         ret = PTR_ERR(inode);
         goto fail;
     }
 
     d_instantiate(dentry, inode);
     ret = 0;
     pending_snapshot->anon_dev = 0;
 fail:
     /* Prevent double freeing of anon_dev */
     if (ret && pending_snapshot->snap)
         pending_snapshot->snap->anon_dev = 0;
     btrfs_put_root(pending_snapshot->snap);
     btrfs_subvolume_release_metadata(root, &pending_snapshot->block_rsv);
 free_pending:
     if (pending_snapshot->anon_dev)
         free_anon_bdev(pending_snapshot->anon_dev);
     kfree(pending_snapshot->root_item);
     btrfs_free_path(pending_snapshot->path);
     kfree(pending_snapshot);
 
     return ret;
 }
 
 /*  copy of may_delete in fs/namei.c()
  *  Check whether we can remove a link victim from directory dir, check
  *  whether the type of victim is right.
  *  1. We can't do it if dir is read-only (done in permission())
  *  2. We should have write and exec permissions on dir
  *  3. We can't remove anything from append-only dir
  *  4. We can't do anything with immutable dir (done in permission())
  *  5. If the sticky bit on dir is set we should either
  *  a. be owner of dir, or
  *  b. be owner of victim, or
  *  c. have CAP_FOWNER capability
  *  6. If the victim is append-only or immutable we can't do anything with
  *     links pointing to it.
  *  7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
  *  8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
  *  9. We can't remove a root or mountpoint.
  * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
  *     nfs_async_unlink().
  */
 
 static int btrfs_may_delete(struct user_namespace *mnt_userns,
                 struct inode *dir, struct dentry *victim, int isdir)
 {
     int error;
 
     if (d_really_is_negative(victim))
         return -ENOENT;
 
     BUG_ON(d_inode(victim->d_parent) != dir);
     audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
 
     error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
     if (error)
         return error;
     if (IS_APPEND(dir))
         return -EPERM;
     if (check_sticky(mnt_userns, dir, d_inode(victim)) ||
         IS_APPEND(d_inode(victim)) || IS_IMMUTABLE(d_inode(victim)) ||
         IS_SWAPFILE(d_inode(victim)))
         return -EPERM;
     if (isdir) {
         if (!d_is_dir(victim))
             return -ENOTDIR;
         if (IS_ROOT(victim))
             return -EBUSY;
     } else if (d_is_dir(victim))
         return -EISDIR;
     if (IS_DEADDIR(dir))
         return -ENOENT;
     if (victim->d_flags & DCACHE_NFSFS_RENAMED)
         return -EBUSY;
     return 0;
 }
 
 /* copy of may_create in fs/namei.c() */
 static inline int btrfs_may_create(struct user_namespace *mnt_userns,
                    struct inode *dir, struct dentry *child)
 {
     if (d_really_is_positive(child))
         return -EEXIST;
     if (IS_DEADDIR(dir))
         return -ENOENT;
     if (!fsuidgid_has_mapping(dir->i_sb, mnt_userns))
         return -EOVERFLOW;
     return inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
 }
 
 /*
  * Create a new subvolume below @parent.  This is largely modeled after
  * sys_mkdirat and vfs_mkdir, but we only do a single component lookup
  * inside this filesystem so it's quite a bit simpler.
  */
 static noinline int btrfs_mksubvol(const struct path *parent,
                    struct user_namespace *mnt_userns,
                    const char *name, int namelen,
                    struct btrfs_root *snap_src,
                    bool readonly,
                    struct btrfs_qgroup_inherit *inherit)
 {
     struct inode *dir = d_inode(parent->dentry);
     struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
     struct dentry *dentry;
     int error;
 
     error = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
     if (error == -EINTR)
         return error;
 
     dentry = lookup_one(mnt_userns, name, parent->dentry, namelen);
     error = PTR_ERR(dentry);
     if (IS_ERR(dentry))
         goto out_unlock;
 
     error = btrfs_may_create(mnt_userns, dir, dentry);
     if (error)
         goto out_dput;
 
     /*
      * even if this name doesn't exist, we may get hash collisions.
      * check for them now when we can safely fail
      */
     error = btrfs_check_dir_item_collision(BTRFS_I(dir)->root,
                            dir->i_ino, name,
                            namelen);
     if (error)
         goto out_dput;
 
     down_read(&fs_info->subvol_sem);
 
     if (btrfs_root_refs(&BTRFS_I(dir)->root->root_item) == 0)
         goto out_up_read;
 
     if (snap_src)
         error = create_snapshot(snap_src, dir, dentry, readonly, inherit);
     else
         error = create_subvol(mnt_userns, dir, dentry, inherit);
 
     if (!error)
         fsnotify_mkdir(dir, dentry);
 out_up_read:
     up_read(&fs_info->subvol_sem);
 out_dput:
     dput(dentry);
 out_unlock:
     btrfs_inode_unlock(dir, 0);
     return error;
 }
 
 static noinline int btrfs_mksnapshot(const struct path *parent,
                    struct user_namespace *mnt_userns,
                    const char *name, int namelen,
                    struct btrfs_root *root,
                    bool readonly,
                    struct btrfs_qgroup_inherit *inherit)
 {
     int ret;
     bool snapshot_force_cow = false;
 
     /*
      * Force new buffered writes to reserve space even when NOCOW is
      * possible. This is to avoid later writeback (running dealloc) to
      * fallback to COW mode and unexpectedly fail with ENOSPC.
      */
     btrfs_drew_read_lock(&root->snapshot_lock);
 
     ret = btrfs_start_delalloc_snapshot(root, false);
     if (ret)
         goto out;
 
     /*
      * All previous writes have started writeback in NOCOW mode, so now
      * we force future writes to fallback to COW mode during snapshot
      * creation.
      */
     atomic_inc(&root->snapshot_force_cow);
     snapshot_force_cow = true;
 
     btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
 
     ret = btrfs_mksubvol(parent, mnt_userns, name, namelen,
                  root, readonly, inherit);
 out:
     if (snapshot_force_cow)
         atomic_dec(&root->snapshot_force_cow);
     btrfs_drew_read_unlock(&root->snapshot_lock);
     return ret;
 }
 
 /*
  * Defrag specific helper to get an extent map.
  *
  * Differences between this and btrfs_get_extent() are:
  *
  * - No extent_map will be added to inode->extent_tree
  *   To reduce memory usage in the long run.
  *
  * - Extra optimization to skip file extents older than @newer_than
  *   By using btrfs_search_forward() we can skip entire file ranges that
  *   have extents created in past transactions, because btrfs_search_forward()
  *   will not visit leaves and nodes with a generation smaller than given
  *   minimal generation threshold (@newer_than).
  *
  * Return valid em if we find a file extent matching the requirement.
  * Return NULL if we can not find a file extent matching the requirement.
  *
  * Return ERR_PTR() for error.
  */
 static struct extent_map *defrag_get_extent(struct btrfs_inode *inode,
                         u64 start, u64 newer_than)
 {
     struct btrfs_root *root = inode->root;
     struct btrfs_file_extent_item *fi;
     struct btrfs_path path = { 0 };
     struct extent_map *em;
     struct btrfs_key key;
     u64 ino = btrfs_ino(inode);
     int ret;
 
     em = alloc_extent_map();
     if (!em) {
         ret = -ENOMEM;
         goto err;
     }
 
     key.objectid = ino;
     key.type = BTRFS_EXTENT_DATA_KEY;
     key.offset = start;
 
     if (newer_than) {
         ret = btrfs_search_forward(root, &key, &path, newer_than);
         if (ret < 0)
             goto err;
         /* Can't find anything newer */
         if (ret > 0)
             goto not_found;
     } else {
         ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
         if (ret < 0)
             goto err;
     }
     if (path.slots[0] >= btrfs_header_nritems(path.nodes[0])) {
         /*
          * If btrfs_search_slot() makes path to point beyond nritems,
          * we should not have an empty leaf, as this inode must at
          * least have its INODE_ITEM.
          */
         ASSERT(btrfs_header_nritems(path.nodes[0]));
         path.slots[0] = btrfs_header_nritems(path.nodes[0]) - 1;
     }
     btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
     /* Perfect match, no need to go one slot back */
     if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY &&
         key.offset == start)
         goto iterate;
 
     /* We didn't find a perfect match, needs to go one slot back */
     if (path.slots[0] > 0) {
         btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
         if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY)
             path.slots[0]--;
     }
 
 iterate:
     /* Iterate through the path to find a file extent covering @start */
     while (true) {
         u64 extent_end;
 
         if (path.slots[0] >= btrfs_header_nritems(path.nodes[0]))
             goto next;
 
         btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
 
         /*
          * We may go one slot back to INODE_REF/XATTR item, then
          * need to go forward until we reach an EXTENT_DATA.
          * But we should still has the correct ino as key.objectid.
          */
         if (WARN_ON(key.objectid < ino) || key.type < BTRFS_EXTENT_DATA_KEY)
             goto next;
 
         /* It's beyond our target range, definitely not extent found */
         if (key.objectid > ino || key.type > BTRFS_EXTENT_DATA_KEY)
             goto not_found;
 
         /*
          *  |   |<- File extent ->|
          *  \- start
          *
          * This means there is a hole between start and key.offset.
          */
         if (key.offset > start) {
             em->start = start;
             em->orig_start = start;
             em->block_start = EXTENT_MAP_HOLE;
             em->len = key.offset - start;
             break;
         }
 
         fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
                     struct btrfs_file_extent_item);
         extent_end = btrfs_file_extent_end(&path);
 
         /*
          *  |<- file extent ->| |
          *              \- start
          *
          * We haven't reached start, search next slot.
          */
         if (extent_end <= start)
             goto next;
 
         /* Now this extent covers @start, convert it to em */
         btrfs_extent_item_to_extent_map(inode, &path, fi, false, em);
         break;
 next:
         ret = btrfs_next_item(root, &path);
         if (ret < 0)
             goto err;
         if (ret > 0)
             goto not_found;
     }
     btrfs_release_path(&path);
     return em;
 
 not_found:
     btrfs_release_path(&path);
     free_extent_map(em);
     return NULL;
 
 err:
     btrfs_release_path(&path);
     free_extent_map(em);
     return ERR_PTR(ret);
 }
 
 static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
                            u64 newer_than, bool locked)
 {
     struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
     struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
     struct extent_map *em;
     const u32 sectorsize = BTRFS_I(inode)->root->fs_info->sectorsize;
 
     /*
      * hopefully we have this extent in the tree already, try without
      * the full extent lock
      */
     read_lock(&em_tree->lock);
     em = lookup_extent_mapping(em_tree, start, sectorsize);
     read_unlock(&em_tree->lock);
 
     /*
      * We can get a merged extent, in that case, we need to re-search
      * tree to get the original em for defrag.
      *
      * If @newer_than is 0 or em::generation < newer_than, we can trust
      * this em, as either we don't care about the generation, or the
      * merged extent map will be rejected anyway.
      */
     if (em && test_bit(EXTENT_FLAG_MERGED, &em->flags) &&
         newer_than && em->generation >= newer_than) {
         free_extent_map(em);
         em = NULL;
     }
 
     if (!em) {
         struct extent_state *cached = NULL;
         u64 end = start + sectorsize - 1;
 
         /* get the big lock and read metadata off disk */
         if (!locked)
             lock_extent_bits(io_tree, start, end, &cached);
         em = defrag_get_extent(BTRFS_I(inode), start, newer_than);
         if (!locked)
             unlock_extent_cached(io_tree, start, end, &cached);
 
         if (IS_ERR(em))
             return NULL;
     }
 
     return em;
 }
 
 static u32 get_extent_max_capacity(const struct btrfs_fs_info *fs_info,
                    const struct extent_map *em)
 {
     if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
         return BTRFS_MAX_COMPRESSED;
     return fs_info->max_extent_size;
 }
 
 static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
                      u32 extent_thresh, u64 newer_than, bool locked)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct extent_map *next;
     bool ret = false;
 
     /* this is the last extent */
     if (em->start + em->len >= i_size_read(inode))
         return false;
 
     /*
      * Here we need to pass @newer_then when checking the next extent, or
      * we will hit a case we mark current extent for defrag, but the next
      * one will not be a target.
      * This will just cause extra IO without really reducing the fragments.
      */
     next = defrag_lookup_extent(inode, em->start + em->len, newer_than, locked);
     /* No more em or hole */
     if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE)
         goto out;
     if (test_bit(EXTENT_FLAG_PREALLOC, &next->flags))
         goto out;
     /*
      * If the next extent is at its max capacity, defragging current extent
      * makes no sense, as the total number of extents won't change.
      */
     if (next->len >= get_extent_max_capacity(fs_info, em))
         goto out;
     /* Skip older extent */
     if (next->generation < newer_than)
         goto out;
     /* Also check extent size */
     if (next->len >= extent_thresh)
         goto out;
 
     ret = true;
 out:
     free_extent_map(next);
     return ret;
 }
 
 /*
  * Prepare one page to be defragged.
  *
  * This will ensure:
  *
  * - Returned page is locked and has been set up properly.
  * - No ordered extent exists in the page.
  * - The page is uptodate.
  *
  * NOTE: Caller should also wait for page writeback after the cluster is
  * prepared, here we don't do writeback wait for each page.
  */
 static struct page *defrag_prepare_one_page(struct btrfs_inode *inode,
                         pgoff_t index)
 {
     struct address_space *mapping = inode->vfs_inode.i_mapping;
     gfp_t mask = btrfs_alloc_write_mask(mapping);
     u64 page_start = (u64)index << PAGE_SHIFT;
     u64 page_end = page_start + PAGE_SIZE - 1;
     struct extent_state *cached_state = NULL;
     struct page *page;
     int ret;
 
 again:
     page = find_or_create_page(mapping, index, mask);
     if (!page)
         return ERR_PTR(-ENOMEM);
 
     /*
      * Since we can defragment files opened read-only, we can encounter
      * transparent huge pages here (see CONFIG_READ_ONLY_THP_FOR_FS). We
      * can't do I/O using huge pages yet, so return an error for now.
      * Filesystem transparent huge pages are typically only used for
      * executables that explicitly enable them, so this isn't very
      * restrictive.
      */
     if (PageCompound(page)) {
         unlock_page(page);
         put_page(page);
         return ERR_PTR(-ETXTBSY);
     }
 
     ret = set_page_extent_mapped(page);
     if (ret < 0) {
         unlock_page(page);
         put_page(page);
         return ERR_PTR(ret);
     }
 
     /* Wait for any existing ordered extent in the range */
     while (1) {
         struct btrfs_ordered_extent *ordered;
 
         lock_extent_bits(&inode->io_tree, page_start, page_end, &cached_state);
         ordered = btrfs_lookup_ordered_range(inode, page_start, PAGE_SIZE);
         unlock_extent_cached(&inode->io_tree, page_start, page_end,
                      &cached_state);
         if (!ordered)
             break;
 
         unlock_page(page);
         btrfs_start_ordered_extent(ordered, 1);
         btrfs_put_ordered_extent(ordered);
         lock_page(page);
         /*
          * We unlocked the page above, so we need check if it was
          * released or not.
          */
         if (page->mapping != mapping || !PagePrivate(page)) {
             unlock_page(page);
             put_page(page);
             goto again;
         }
     }
 
     /*
      * Now the page range has no ordered extent any more.  Read the page to
      * make it uptodate.
      */
     if (!PageUptodate(page)) {
         btrfs_read_folio(NULL, page_folio(page));
         lock_page(page);
         if (page->mapping != mapping || !PagePrivate(page)) {
             unlock_page(page);
             put_page(page);
             goto again;
         }
         if (!PageUptodate(page)) {
             unlock_page(page);
             put_page(page);
             return ERR_PTR(-EIO);
         }
     }
     return page;
 }
 
 struct defrag_target_range {
     struct list_head list;
     u64 start;
     u64 len;
 };
 
 /*
  * Collect all valid target extents.
  *
  * @start:     file offset to lookup
  * @len:       length to lookup
  * @extent_thresh: file extent size threshold, any extent size >= this value
  *         will be ignored
  * @newer_than:    only defrag extents newer than this value
  * @do_compress:   whether the defrag is doing compression
  *         if true, @extent_thresh will be ignored and all regular
  *         file extents meeting @newer_than will be targets.
  * @locked:    if the range has already held extent lock
  * @target_list:   list of targets file extents
  */
 static int defrag_collect_targets(struct btrfs_inode *inode,
                   u64 start, u64 len, u32 extent_thresh,
                   u64 newer_than, bool do_compress,
                   bool locked, struct list_head *target_list,
                   u64 *last_scanned_ret)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     bool last_is_target = false;
     u64 cur = start;
     int ret = 0;
 
     while (cur < start + len) {
         struct extent_map *em;
         struct defrag_target_range *new;
         bool next_mergeable = true;
         u64 range_len;
 
         last_is_target = false;
         em = defrag_lookup_extent(&inode->vfs_inode, cur,
                       newer_than, locked);
         if (!em)
             break;
 
         /*
          * If the file extent is an inlined one, we may still want to
          * defrag it (fallthrough) if it will cause a regular extent.
          * This is for users who want to convert inline extents to
          * regular ones through max_inline= mount option.
          */
         if (em->block_start == EXTENT_MAP_INLINE &&
             em->len <= inode->root->fs_info->max_inline)
             goto next;
 
         /* Skip hole/delalloc/preallocated extents */
         if (em->block_start == EXTENT_MAP_HOLE ||
             em->block_start == EXTENT_MAP_DELALLOC ||
             test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
             goto next;
 
         /* Skip older extent */
         if (em->generation < newer_than)
             goto next;
 
         /* This em is under writeback, no need to defrag */
         if (em->generation == (u64)-1)
             goto next;
 
         /*
          * Our start offset might be in the middle of an existing extent
          * map, so take that into account.
          */
         range_len = em->len - (cur - em->start);
         /*
          * If this range of the extent map is already flagged for delalloc,
          * skip it, because:
          *
          * 1) We could deadlock later, when trying to reserve space for
          *    delalloc, because in case we can't immediately reserve space
          *    the flusher can start delalloc and wait for the respective
          *    ordered extents to complete. The deadlock would happen
          *    because we do the space reservation while holding the range
          *    locked, and starting writeback, or finishing an ordered
          *    extent, requires locking the range;
          *
          * 2) If there's delalloc there, it means there's dirty pages for
          *    which writeback has not started yet (we clean the delalloc
          *    flag when starting writeback and after creating an ordered
          *    extent). If we mark pages in an adjacent range for defrag,
          *    then we will have a larger contiguous range for delalloc,
          *    very likely resulting in a larger extent after writeback is
          *    triggered (except in a case of free space fragmentation).
          */
         if (test_range_bit(&inode->io_tree, cur, cur + range_len - 1,
                    EXTENT_DELALLOC, 0, NULL))
             goto next;
 
         /*
          * For do_compress case, we want to compress all valid file
          * extents, thus no @extent_thresh or mergeable check.
          */
         if (do_compress)
             goto add;
 
         /* Skip too large extent */
         if (range_len >= extent_thresh)
             goto next;
 
         /*
          * Skip extents already at its max capacity, this is mostly for
          * compressed extents, which max cap is only 128K.
          */
         if (em->len >= get_extent_max_capacity(fs_info, em))
             goto next;
 
         /*
          * Normally there are no more extents after an inline one, thus
          * @next_mergeable will normally be false and not defragged.
          * So if an inline extent passed all above checks, just add it
          * for defrag, and be converted to regular extents.
          */
         if (em->block_start == EXTENT_MAP_INLINE)
             goto add;
 
         next_mergeable = defrag_check_next_extent(&inode->vfs_inode, em,
                         extent_thresh, newer_than, locked);
         if (!next_mergeable) {
             struct defrag_target_range *last;
 
             /* Empty target list, no way to merge with last entry */
             if (list_empty(target_list))
                 goto next;
             last = list_entry(target_list->prev,
                       struct defrag_target_range, list);
             /* Not mergeable with last entry */
             if (last->start + last->len != cur)
                 goto next;
 
             /* Mergeable, fall through to add it to @target_list. */
         }
 
 add:
         last_is_target = true;
         range_len = min(extent_map_end(em), start + len) - cur;
         /*
          * This one is a good target, check if it can be merged into
          * last range of the target list.
          */
         if (!list_empty(target_list)) {
             struct defrag_target_range *last;
 
             last = list_entry(target_list->prev,
                       struct defrag_target_range, list);
             ASSERT(last->start + last->len <= cur);
             if (last->start + last->len == cur) {
                 /* Mergeable, enlarge the last entry */
                 last->len += range_len;
                 goto next;
             }
             /* Fall through to allocate a new entry */
         }
 
         /* Allocate new defrag_target_range */
         new = kmalloc(sizeof(*new), GFP_NOFS);
         if (!new) {
             free_extent_map(em);
             ret = -ENOMEM;
             break;
         }
         new->start = cur;
         new->len = range_len;
         list_add_tail(&new->list, target_list);
 
 next:
         cur = extent_map_end(em);
         free_extent_map(em);
     }
     if (ret < 0) {
         struct defrag_target_range *entry;
         struct defrag_target_range *tmp;
 
         list_for_each_entry_safe(entry, tmp, target_list, list) {
             list_del_init(&entry->list);
             kfree(entry);
         }
     }
     if (!ret && last_scanned_ret) {
         /*
          * If the last extent is not a target, the caller can skip to
          * the end of that extent.
          * Otherwise, we can only go the end of the specified range.
          */
         if (!last_is_target)
             *last_scanned_ret = max(cur, *last_scanned_ret);
         else
             *last_scanned_ret = max(start + len, *last_scanned_ret);
     }
     return ret;
 }
 
 #define CLUSTER_SIZE    (SZ_256K)
 static_assert(IS_ALIGNED(CLUSTER_SIZE, PAGE_SIZE));
 
 /*
  * Defrag one contiguous target range.
  *
  * @inode:  target inode
  * @target: target range to defrag
  * @pages:  locked pages covering the defrag range
  * @nr_pages:   number of locked pages
  *
  * Caller should ensure:
  *
  * - Pages are prepared
  *   Pages should be locked, no ordered extent in the pages range,
  *   no writeback.
  *
  * - Extent bits are locked
  */
 static int defrag_one_locked_target(struct btrfs_inode *inode,
                     struct defrag_target_range *target,
                     struct page **pages, int nr_pages,
                     struct extent_state **cached_state)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     struct extent_changeset *data_reserved = NULL;
     const u64 start = target->start;
     const u64 len = target->len;
     unsigned long last_index = (start + len - 1) >> PAGE_SHIFT;
     unsigned long start_index = start >> PAGE_SHIFT;
     unsigned long first_index = page_index(pages[0]);
     int ret = 0;
     int i;
 
     ASSERT(last_index - first_index + 1 <= nr_pages);
 
     ret = btrfs_delalloc_reserve_space(inode, &data_reserved, start, len);
     if (ret < 0)
         return ret;
     clear_extent_bit(&inode->io_tree, start, start + len - 1,
              EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
              EXTENT_DEFRAG, 0, 0, cached_state);
     set_extent_defrag(&inode->io_tree, start, start + len - 1, cached_state);
 
     /* Update the page status */
     for (i = start_index - first_index; i <= last_index - first_index; i++) {
         ClearPageChecked(pages[i]);
         btrfs_page_clamp_set_dirty(fs_info, pages[i], start, len);
     }
     btrfs_delalloc_release_extents(inode, len);
     extent_changeset_free(data_reserved);
 
     return ret;
 }
 
 static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
                 u32 extent_thresh, u64 newer_than, bool do_compress,
                 u64 *last_scanned_ret)
 {
     struct extent_state *cached_state = NULL;
     struct defrag_target_range *entry;
     struct defrag_target_range *tmp;
     LIST_HEAD(target_list);
     struct page **pages;
     const u32 sectorsize = inode->root->fs_info->sectorsize;
     u64 last_index = (start + len - 1) >> PAGE_SHIFT;
     u64 start_index = start >> PAGE_SHIFT;
     unsigned int nr_pages = last_index - start_index + 1;
     int ret = 0;
     int i;
 
     ASSERT(nr_pages <= CLUSTER_SIZE / PAGE_SIZE);
     ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(len, sectorsize));
 
     pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
     if (!pages)
         return -ENOMEM;
 
     /* Prepare all pages */
     for (i = 0; i < nr_pages; i++) {
         pages[i] = defrag_prepare_one_page(inode, start_index + i);
         if (IS_ERR(pages[i])) {
             ret = PTR_ERR(pages[i]);
             pages[i] = NULL;
             goto free_pages;
         }
     }
     for (i = 0; i < nr_pages; i++)
         wait_on_page_writeback(pages[i]);
 
     /* Lock the pages range */
     lock_extent_bits(&inode->io_tree, start_index << PAGE_SHIFT,
              (last_index << PAGE_SHIFT) + PAGE_SIZE - 1,
              &cached_state);
     /*
      * Now we have a consistent view about the extent map, re-check
      * which range really needs to be defragged.
      *
      * And this time we have extent locked already, pass @locked = true
      * so that we won't relock the extent range and cause deadlock.
      */
     ret = defrag_collect_targets(inode, start, len, extent_thresh,
                      newer_than, do_compress, true,
                      &target_list, last_scanned_ret);
     if (ret < 0)
         goto unlock_extent;
 
     list_for_each_entry(entry, &target_list, list) {
         ret = defrag_one_locked_target(inode, entry, pages, nr_pages,
                            &cached_state);
         if (ret < 0)
             break;
     }
 
     list_for_each_entry_safe(entry, tmp, &target_list, list) {
         list_del_init(&entry->list);
         kfree(entry);
     }
 unlock_extent:
     unlock_extent_cached(&inode->io_tree, start_index << PAGE_SHIFT,
                  (last_index << PAGE_SHIFT) + PAGE_SIZE - 1,
                  &cached_state);
 free_pages:
     for (i = 0; i < nr_pages; i++) {
         if (pages[i]) {
             unlock_page(pages[i]);
             put_page(pages[i]);
         }
     }
     kfree(pages);
     return ret;
 }
 
 static int defrag_one_cluster(struct btrfs_inode *inode,
                   struct file_ra_state *ra,
                   u64 start, u32 len, u32 extent_thresh,
                   u64 newer_than, bool do_compress,
                   unsigned long *sectors_defragged,
                   unsigned long max_sectors,
                   u64 *last_scanned_ret)
 {
     const u32 sectorsize = inode->root->fs_info->sectorsize;
     struct defrag_target_range *entry;
     struct defrag_target_range *tmp;
     LIST_HEAD(target_list);
     int ret;
 
     ret = defrag_collect_targets(inode, start, len, extent_thresh,
                      newer_than, do_compress, false,
                      &target_list, NULL);
     if (ret < 0)
         goto out;
 
     list_for_each_entry(entry, &target_list, list) {
         u32 range_len = entry->len;
 
         /* Reached or beyond the limit */
         if (max_sectors && *sectors_defragged >= max_sectors) {
             ret = 1;
             break;
         }
 
         if (max_sectors)
             range_len = min_t(u32, range_len,
                 (max_sectors - *sectors_defragged) * sectorsize);
 
         /*
          * If defrag_one_range() has updated last_scanned_ret,
          * our range may already be invalid (e.g. hole punched).
          * Skip if our range is before last_scanned_ret, as there is
          * no need to defrag the range anymore.
          */
         if (entry->start + range_len <= *last_scanned_ret)
             continue;
 
         if (ra)
             page_cache_sync_readahead(inode->vfs_inode.i_mapping,
                 ra, NULL, entry->start >> PAGE_SHIFT,
                 ((entry->start + range_len - 1) >> PAGE_SHIFT) -
                 (entry->start >> PAGE_SHIFT) + 1);
         /*
          * Here we may not defrag any range if holes are punched before
          * we locked the pages.
          * But that's fine, it only affects the @sectors_defragged
          * accounting.
          */
         ret = defrag_one_range(inode, entry->start, range_len,
                        extent_thresh, newer_than, do_compress,
                        last_scanned_ret);
         if (ret < 0)
             break;
         *sectors_defragged += range_len >>
                       inode->root->fs_info->sectorsize_bits;
     }
 out:
     list_for_each_entry_safe(entry, tmp, &target_list, list) {
         list_del_init(&entry->list);
         kfree(entry);
     }
     if (ret >= 0)
         *last_scanned_ret = max(*last_scanned_ret, start + len);
     return ret;
 }
 
 /*
  * Entry point to file defragmentation.
  *
  * @inode:     inode to be defragged
  * @ra:        readahead state (can be NUL)
  * @range:     defrag options including range and flags
  * @newer_than:    minimum transid to defrag
  * @max_to_defrag: max number of sectors to be defragged, if 0, the whole inode
  *         will be defragged.
  *
  * Return <0 for error.
  * Return >=0 for the number of sectors defragged, and range->start will be updated
  * to indicate the file offset where next defrag should be started at.
  * (Mostly for autodefrag, which sets @max_to_defrag thus we may exit early without
  *  defragging all the range).
  */
 int btrfs_defrag_file(struct inode *inode, struct file_ra_state *ra,
               struct btrfs_ioctl_defrag_range_args *range,
               u64 newer_than, unsigned long max_to_defrag)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     unsigned long sectors_defragged = 0;
     u64 isize = i_size_read(inode);
     u64 cur;
     u64 last_byte;
     bool do_compress = range->flags & BTRFS_DEFRAG_RANGE_COMPRESS;
     bool ra_allocated = false;
     int compress_type = BTRFS_COMPRESS_ZLIB;
     int ret = 0;
     u32 extent_thresh = range->extent_thresh;
     pgoff_t start_index;
 
     if (isize == 0)
         return 0;
 
     if (range->start >= isize)
         return -EINVAL;
 
     if (do_compress) {
         if (range->compress_type >= BTRFS_NR_COMPRESS_TYPES)
             return -EINVAL;
         if (range->compress_type)
             compress_type = range->compress_type;
     }
 
     if (extent_thresh == 0)
         extent_thresh = SZ_256K;
 
     if (range->start + range->len > range->start) {
         /* Got a specific range */
         last_byte = min(isize, range->start + range->len);
     } else {
         /* Defrag until file end */
         last_byte = isize;
     }
 
     /* Align the range */
     cur = round_down(range->start, fs_info->sectorsize);
     last_byte = round_up(last_byte, fs_info->sectorsize) - 1;
 
     /*
      * If we were not given a ra, allocate a readahead context. As
      * readahead is just an optimization, defrag will work without it so
      * we don't error out.
      */
     if (!ra) {
         ra_allocated = true;
         ra = kzalloc(sizeof(*ra), GFP_KERNEL);
         if (ra)
             file_ra_state_init(ra, inode->i_mapping);
     }
 
     /*
      * Make writeback start from the beginning of the range, so that the
      * defrag range can be written sequentially.
      */
     start_index = cur >> PAGE_SHIFT;
     if (start_index < inode->i_mapping->writeback_index)
         inode->i_mapping->writeback_index = start_index;
 
     while (cur < last_byte) {
         const unsigned long prev_sectors_defragged = sectors_defragged;
         u64 last_scanned = cur;
         u64 cluster_end;
 
         if (btrfs_defrag_cancelled(fs_info)) {
             ret = -EAGAIN;
             break;
         }
 
         /* We want the cluster end at page boundary when possible */
         cluster_end = (((cur >> PAGE_SHIFT) +
                    (SZ_256K >> PAGE_SHIFT)) << PAGE_SHIFT) - 1;
         cluster_end = min(cluster_end, last_byte);
 
         btrfs_inode_lock(inode, 0);
         if (IS_SWAPFILE(inode)) {
             ret = -ETXTBSY;
             btrfs_inode_unlock(inode, 0);
             break;
         }
         if (!(inode->i_sb->s_flags & SB_ACTIVE)) {
             btrfs_inode_unlock(inode, 0);
             break;
         }
         if (do_compress)
             BTRFS_I(inode)->defrag_compress = compress_type;
         ret = defrag_one_cluster(BTRFS_I(inode), ra, cur,
                 cluster_end + 1 - cur, extent_thresh,
                 newer_than, do_compress, &sectors_defragged,
                 max_to_defrag, &last_scanned);
 
         if (sectors_defragged > prev_sectors_defragged)
             balance_dirty_pages_ratelimited(inode->i_mapping);
 
         btrfs_inode_unlock(inode, 0);
         if (ret < 0)
             break;
         cur = max(cluster_end + 1, last_scanned);
         if (ret > 0) {
             ret = 0;
             break;
         }
         cond_resched();
     }
 
     if (ra_allocated)
         kfree(ra);
     /*
      * Update range.start for autodefrag, this will indicate where to start
      * in next run.
      */
     range->start = cur;
     if (sectors_defragged) {
         /*
          * We have defragged some sectors, for compression case they
          * need to be written back immediately.
          */
         if (range->flags & BTRFS_DEFRAG_RANGE_START_IO) {
             filemap_flush(inode->i_mapping);
             if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
                      &BTRFS_I(inode)->runtime_flags))
                 filemap_flush(inode->i_mapping);
         }
         if (range->compress_type == BTRFS_COMPRESS_LZO)
             btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
         else if (range->compress_type == BTRFS_COMPRESS_ZSTD)
             btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
         ret = sectors_defragged;
     }
     if (do_compress) {
         btrfs_inode_lock(inode, 0);
         BTRFS_I(inode)->defrag_compress = BTRFS_COMPRESS_NONE;
         btrfs_inode_unlock(inode, 0);
     }
     return ret;
 }
 
 /*
  * Try to start exclusive operation @type or cancel it if it's running.
  *
  * Return:
  *   0        - normal mode, newly claimed op started
  *  >0        - normal mode, something else is running,
  *              return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS to user space
  * ECANCELED  - cancel mode, successful cancel
  * ENOTCONN   - cancel mode, operation not running anymore
  */
 static int exclop_start_or_cancel_reloc(struct btrfs_fs_info *fs_info,
             enum btrfs_exclusive_operation type, bool cancel)
 {
     if (!cancel) {
         /* Start normal op */
         if (!btrfs_exclop_start(fs_info, type))
             return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
         /* Exclusive operation is now claimed */
         return 0;
     }
 
     /* Cancel running op */
     if (btrfs_exclop_start_try_lock(fs_info, type)) {
         /*
          * This blocks any exclop finish from setting it to NONE, so we
          * request cancellation. Either it runs and we will wait for it,
          * or it has finished and no waiting will happen.
          */
         atomic_inc(&fs_info->reloc_cancel_req);
         btrfs_exclop_start_unlock(fs_info);
 
         if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
             wait_on_bit(&fs_info->flags, BTRFS_FS_RELOC_RUNNING,
                     TASK_INTERRUPTIBLE);
 
         return -ECANCELED;
     }
 
     /* Something else is running or none */
     return -ENOTCONN;
 }
 
 static noinline int btrfs_ioctl_resize(struct file *file,
                     void __user *arg)
 {
     BTRFS_DEV_LOOKUP_ARGS(args);
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     u64 new_size;
     u64 old_size;
     u64 devid = 1;
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_ioctl_vol_args *vol_args;
     struct btrfs_trans_handle *trans;
     struct btrfs_device *device = NULL;
     char *sizestr;
     char *retptr;
     char *devstr = NULL;
     int ret = 0;
     int mod = 0;
     bool cancel;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     /*
      * Read the arguments before checking exclusivity to be able to
      * distinguish regular resize and cancel
      */
     vol_args = memdup_user(arg, sizeof(*vol_args));
     if (IS_ERR(vol_args)) {
         ret = PTR_ERR(vol_args);
         goto out_drop;
     }
     vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
     sizestr = vol_args->name;
     cancel = (strcmp("cancel", sizestr) == 0);
     ret = exclop_start_or_cancel_reloc(fs_info, BTRFS_EXCLOP_RESIZE, cancel);
     if (ret)
         goto out_free;
     /* Exclusive operation is now claimed */
 
     devstr = strchr(sizestr, ':');
     if (devstr) {
         sizestr = devstr + 1;
         *devstr = '\0';
         devstr = vol_args->name;
         ret = kstrtoull(devstr, 10, &devid);
         if (ret)
             goto out_finish;
         if (!devid) {
             ret = -EINVAL;
             goto out_finish;
         }
         btrfs_info(fs_info, "resizing devid %llu", devid);
     }
 
     args.devid = devid;
     device = btrfs_find_device(fs_info->fs_devices, &args);
     if (!device) {
         btrfs_info(fs_info, "resizer unable to find device %llu",
                devid);
         ret = -ENODEV;
         goto out_finish;
     }
 
     if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
         btrfs_info(fs_info,
                "resizer unable to apply on readonly device %llu",
                devid);
         ret = -EPERM;
         goto out_finish;
     }
 
     if (!strcmp(sizestr, "max"))
         new_size = bdev_nr_bytes(device->bdev);
     else {
         if (sizestr[0] == '-') {
             mod = -1;
             sizestr++;
         } else if (sizestr[0] == '+') {
             mod = 1;
             sizestr++;
         }
         new_size = memparse(sizestr, &retptr);
         if (*retptr != '\0' || new_size == 0) {
             ret = -EINVAL;
             goto out_finish;
         }
     }
 
     if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
         ret = -EPERM;
         goto out_finish;
     }
 
     old_size = btrfs_device_get_total_bytes(device);
 
     if (mod < 0) {
         if (new_size > old_size) {
             ret = -EINVAL;
             goto out_finish;
         }
         new_size = old_size - new_size;
     } else if (mod > 0) {
         if (new_size > ULLONG_MAX - old_size) {
             ret = -ERANGE;
             goto out_finish;
         }
         new_size = old_size + new_size;
     }
 
     if (new_size < SZ_256M) {
         ret = -EINVAL;
         goto out_finish;
     }
     if (new_size > bdev_nr_bytes(device->bdev)) {
         ret = -EFBIG;
         goto out_finish;
     }
 
     new_size = round_down(new_size, fs_info->sectorsize);
 
     if (new_size > old_size) {
         trans = btrfs_start_transaction(root, 0);
         if (IS_ERR(trans)) {
             ret = PTR_ERR(trans);
             goto out_finish;
         }
         ret = btrfs_grow_device(trans, device, new_size);
         btrfs_commit_transaction(trans);
     } else if (new_size < old_size) {
         ret = btrfs_shrink_device(device, new_size);
     } /* equal, nothing need to do */
 
     if (ret == 0 && new_size != old_size)
         btrfs_info_in_rcu(fs_info,
             "resize device %s (devid %llu) from %llu to %llu",
             rcu_str_deref(device->name), device->devid,
             old_size, new_size);
 out_finish:
     btrfs_exclop_finish(fs_info);
 out_free:
     kfree(vol_args);
 out_drop:
     mnt_drop_write_file(file);
     return ret;
 }
 
 static noinline int __btrfs_ioctl_snap_create(struct file *file,
                 struct user_namespace *mnt_userns,
                 const char *name, unsigned long fd, int subvol,
                 bool readonly,
                 struct btrfs_qgroup_inherit *inherit)
 {
     int namelen;
     int ret = 0;
 
     if (!S_ISDIR(file_inode(file)->i_mode))
         return -ENOTDIR;
 
     ret = mnt_want_write_file(file);
     if (ret)
         goto out;
 
     namelen = strlen(name);
     if (strchr(name, '/')) {
         ret = -EINVAL;
         goto out_drop_write;
     }
 
     if (name[0] == '.' &&
        (namelen == 1 || (name[1] == '.' && namelen == 2))) {
         ret = -EEXIST;
         goto out_drop_write;
     }
 
     if (subvol) {
         ret = btrfs_mksubvol(&file->f_path, mnt_userns, name,
                      namelen, NULL, readonly, inherit);
     } else {
         struct fd src = fdget(fd);
         struct inode *src_inode;
         if (!src.file) {
             ret = -EINVAL;
             goto out_drop_write;
         }
 
         src_inode = file_inode(src.file);
         if (src_inode->i_sb != file_inode(file)->i_sb) {
             btrfs_info(BTRFS_I(file_inode(file))->root->fs_info,
                    "Snapshot src from another FS");
             ret = -EXDEV;
         } else if (!inode_owner_or_capable(mnt_userns, src_inode)) {
             /*
              * Subvolume creation is not restricted, but snapshots
              * are limited to own subvolumes only
              */
             ret = -EPERM;
         } else {
             ret = btrfs_mksnapshot(&file->f_path, mnt_userns,
                            name, namelen,
                            BTRFS_I(src_inode)->root,
                            readonly, inherit);
         }
         fdput(src);
     }
 out_drop_write:
     mnt_drop_write_file(file);
 out:
     return ret;
 }
 
 static noinline int btrfs_ioctl_snap_create(struct file *file,
                         void __user *arg, int subvol)
 {
     struct btrfs_ioctl_vol_args *vol_args;
     int ret;
 
     if (!S_ISDIR(file_inode(file)->i_mode))
         return -ENOTDIR;
 
     vol_args = memdup_user(arg, sizeof(*vol_args));
     if (IS_ERR(vol_args))
         return PTR_ERR(vol_args);
     vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
 
     ret = __btrfs_ioctl_snap_create(file, file_mnt_user_ns(file),
                     vol_args->name, vol_args->fd, subvol,
                     false, NULL);
 
     kfree(vol_args);
     return ret;
 }
 
 static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
                            void __user *arg, int subvol)
 {
     struct btrfs_ioctl_vol_args_v2 *vol_args;
     int ret;
     bool readonly = false;
     struct btrfs_qgroup_inherit *inherit = NULL;
 
     if (!S_ISDIR(file_inode(file)->i_mode))
         return -ENOTDIR;
 
     vol_args = memdup_user(arg, sizeof(*vol_args));
     if (IS_ERR(vol_args))
         return PTR_ERR(vol_args);
     vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
 
     if (vol_args->flags & ~BTRFS_SUBVOL_CREATE_ARGS_MASK) {
         ret = -EOPNOTSUPP;
         goto free_args;
     }
 
     if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
         readonly = true;
     if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
         u64 nums;
 
         if (vol_args->size < sizeof(*inherit) ||
             vol_args->size > PAGE_SIZE) {
             ret = -EINVAL;
             goto free_args;
         }
         inherit = memdup_user(vol_args->qgroup_inherit, vol_args->size);
         if (IS_ERR(inherit)) {
             ret = PTR_ERR(inherit);
             goto free_args;
         }
 
         if (inherit->num_qgroups > PAGE_SIZE ||
             inherit->num_ref_copies > PAGE_SIZE ||
             inherit->num_excl_copies > PAGE_SIZE) {
             ret = -EINVAL;
             goto free_inherit;
         }
 
         nums = inherit->num_qgroups + 2 * inherit->num_ref_copies +
                2 * inherit->num_excl_copies;
         if (vol_args->size != struct_size(inherit, qgroups, nums)) {
             ret = -EINVAL;
             goto free_inherit;
         }
     }
 
     ret = __btrfs_ioctl_snap_create(file, file_mnt_user_ns(file),
                     vol_args->name, vol_args->fd, subvol,
                     readonly, inherit);
     if (ret)
         goto free_inherit;
 free_inherit:
     kfree(inherit);
 free_args:
     kfree(vol_args);
     return ret;
 }
 
 static noinline int btrfs_ioctl_subvol_getflags(struct inode *inode,
                         void __user *arg)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     int ret = 0;
     u64 flags = 0;
 
     if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID)
         return -EINVAL;
 
     down_read(&fs_info->subvol_sem);
     if (btrfs_root_readonly(root))
         flags |= BTRFS_SUBVOL_RDONLY;
     up_read(&fs_info->subvol_sem);
 
     if (copy_to_user(arg, &flags, sizeof(flags)))
         ret = -EFAULT;
 
     return ret;
 }
 
 static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
                           void __user *arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_trans_handle *trans;
     u64 root_flags;
     u64 flags;
     int ret = 0;
 
     if (!inode_owner_or_capable(file_mnt_user_ns(file), inode))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         goto out;
 
     if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
         ret = -EINVAL;
         goto out_drop_write;
     }
 
     if (copy_from_user(&flags, arg, sizeof(flags))) {
         ret = -EFAULT;
         goto out_drop_write;
     }
 
     if (flags & ~BTRFS_SUBVOL_RDONLY) {
         ret = -EOPNOTSUPP;
         goto out_drop_write;
     }
 
     down_write(&fs_info->subvol_sem);
 
     /* nothing to do */
     if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root))
         goto out_drop_sem;
 
     root_flags = btrfs_root_flags(&root->root_item);
     if (flags & BTRFS_SUBVOL_RDONLY) {
         btrfs_set_root_flags(&root->root_item,
                      root_flags | BTRFS_ROOT_SUBVOL_RDONLY);
     } else {
         /*
          * Block RO -> RW transition if this subvolume is involved in
          * send
          */
         spin_lock(&root->root_item_lock);
         if (root->send_in_progress == 0) {
             btrfs_set_root_flags(&root->root_item,
                      root_flags & ~BTRFS_ROOT_SUBVOL_RDONLY);
             spin_unlock(&root->root_item_lock);
         } else {
             spin_unlock(&root->root_item_lock);
             btrfs_warn(fs_info,
                    "Attempt to set subvolume %llu read-write during send",
                    root->root_key.objectid);
             ret = -EPERM;
             goto out_drop_sem;
         }
     }
 
     trans = btrfs_start_transaction(root, 1);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out_reset;
     }
 
     ret = btrfs_update_root(trans, fs_info->tree_root,
                 &root->root_key, &root->root_item);
     if (ret < 0) {
         btrfs_end_transaction(trans);
         goto out_reset;
     }
 
     ret = btrfs_commit_transaction(trans);
 
 out_reset:
     if (ret)
         btrfs_set_root_flags(&root->root_item, root_flags);
 out_drop_sem:
     up_write(&fs_info->subvol_sem);
 out_drop_write:
     mnt_drop_write_file(file);
 out:
     return ret;
 }
 
 static noinline int key_in_sk(struct btrfs_key *key,
                   struct btrfs_ioctl_search_key *sk)
 {
     struct btrfs_key test;
     int ret;
 
     test.objectid = sk->min_objectid;
     test.type = sk->min_type;
     test.offset = sk->min_offset;
 
     ret = btrfs_comp_cpu_keys(key, &test);
     if (ret < 0)
         return 0;
 
     test.objectid = sk->max_objectid;
     test.type = sk->max_type;
     test.offset = sk->max_offset;
 
     ret = btrfs_comp_cpu_keys(key, &test);
     if (ret > 0)
         return 0;
     return 1;
 }
 
 static noinline int copy_to_sk(struct btrfs_path *path,
                    struct btrfs_key *key,
                    struct btrfs_ioctl_search_key *sk,
                    size_t *buf_size,
                    char __user *ubuf,
                    unsigned long *sk_offset,
                    int *num_found)
 {
     u64 found_transid;
     struct extent_buffer *leaf;
     struct btrfs_ioctl_search_header sh;
     struct btrfs_key test;
     unsigned long item_off;
     unsigned long item_len;
     int nritems;
     int i;
     int slot;
     int ret = 0;
 
     leaf = path->nodes[0];
     slot = path->slots[0];
     nritems = btrfs_header_nritems(leaf);
 
     if (btrfs_header_generation(leaf) > sk->max_transid) {
         i = nritems;
         goto advance_key;
     }
     found_transid = btrfs_header_generation(leaf);
 
     for (i = slot; i < nritems; i++) {
         item_off = btrfs_item_ptr_offset(leaf, i);
         item_len = btrfs_item_size(leaf, i);
 
         btrfs_item_key_to_cpu(leaf, key, i);
         if (!key_in_sk(key, sk))
             continue;
 
         if (sizeof(sh) + item_len > *buf_size) {
             if (*num_found) {
                 ret = 1;
                 goto out;
             }
 
             /*
              * return one empty item back for v1, which does not
              * handle -EOVERFLOW
              */
 
             *buf_size = sizeof(sh) + item_len;
             item_len = 0;
             ret = -EOVERFLOW;
         }
 
         if (sizeof(sh) + item_len + *sk_offset > *buf_size) {
             ret = 1;
             goto out;
         }
 
         sh.objectid = key->objectid;
         sh.offset = key->offset;
         sh.type = key->type;
         sh.len = item_len;
         sh.transid = found_transid;
 
         /*
          * Copy search result header. If we fault then loop again so we
          * can fault in the pages and -EFAULT there if there's a
          * problem. Otherwise we'll fault and then copy the buffer in
          * properly this next time through
          */
         if (copy_to_user_nofault(ubuf + *sk_offset, &sh, sizeof(sh))) {
             ret = 0;
             goto out;
         }
 
         *sk_offset += sizeof(sh);
 
         if (item_len) {
             char __user *up = ubuf + *sk_offset;
             /*
              * Copy the item, same behavior as above, but reset the
              * * sk_offset so we copy the full thing again.
              */
             if (read_extent_buffer_to_user_nofault(leaf, up,
                         item_off, item_len)) {
                 ret = 0;
                 *sk_offset -= sizeof(sh);
                 goto out;
             }
 
             *sk_offset += item_len;
         }
         (*num_found)++;
 
         if (ret) /* -EOVERFLOW from above */
             goto out;
 
         if (*num_found >= sk->nr_items) {
             ret = 1;
             goto out;
         }
     }
 advance_key:
     ret = 0;
     test.objectid = sk->max_objectid;
     test.type = sk->max_type;
     test.offset = sk->max_offset;
     if (btrfs_comp_cpu_keys(key, &test) >= 0)
         ret = 1;
     else if (key->offset < (u64)-1)
         key->offset++;
     else if (key->type < (u8)-1) {
         key->offset = 0;
         key->type++;
     } else if (key->objectid < (u64)-1) {
         key->offset = 0;
         key->type = 0;
         key->objectid++;
     } else
         ret = 1;
 out:
     /*
      *  0: all items from this leaf copied, continue with next
      *  1: * more items can be copied, but unused buffer is too small
      *     * all items were found
      *     Either way, it will stops the loop which iterates to the next
      *     leaf
      *  -EOVERFLOW: item was to large for buffer
      *  -EFAULT: could not copy extent buffer back to userspace
      */
     return ret;
 }
 
 static noinline int search_ioctl(struct inode *inode,
                  struct btrfs_ioctl_search_key *sk,
                  size_t *buf_size,
                  char __user *ubuf)
 {
     struct btrfs_fs_info *info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root;
     struct btrfs_key key;
     struct btrfs_path *path;
     int ret;
     int num_found = 0;
     unsigned long sk_offset = 0;
 
     if (*buf_size < sizeof(struct btrfs_ioctl_search_header)) {
         *buf_size = sizeof(struct btrfs_ioctl_search_header);
         return -EOVERFLOW;
     }
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     if (sk->tree_id == 0) {
         /* search the root of the inode that was passed */
         root = btrfs_grab_root(BTRFS_I(inode)->root);
     } else {
         root = btrfs_get_fs_root(info, sk->tree_id, true);
         if (IS_ERR(root)) {
             btrfs_free_path(path);
             return PTR_ERR(root);
         }
     }
 
     key.objectid = sk->min_objectid;
     key.type = sk->min_type;
     key.offset = sk->min_offset;
 
     while (1) {
         ret = -EFAULT;
         /*
          * Ensure that the whole user buffer is faulted in at sub-page
          * granularity, otherwise the loop may live-lock.
          */
         if (fault_in_subpage_writeable(ubuf + sk_offset,
                            *buf_size - sk_offset))
             break;
 
         ret = btrfs_search_forward(root, &key, path, sk->min_transid);
         if (ret != 0) {
             if (ret > 0)
                 ret = 0;
             goto err;
         }
         ret = copy_to_sk(path, &key, sk, buf_size, ubuf,
                  &sk_offset, &num_found);
         btrfs_release_path(path);
         if (ret)
             break;
 
     }
     if (ret > 0)
         ret = 0;
 err:
     sk->nr_items = num_found;
     btrfs_put_root(root);
     btrfs_free_path(path);
     return ret;
 }
 
 static noinline int btrfs_ioctl_tree_search(struct inode *inode,
                         void __user *argp)
 {
     struct btrfs_ioctl_search_args __user *uargs = argp;
     struct btrfs_ioctl_search_key sk;
     int ret;
     size_t buf_size;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     if (copy_from_user(&sk, &uargs->key, sizeof(sk)))
         return -EFAULT;
 
     buf_size = sizeof(uargs->buf);
 
     ret = search_ioctl(inode, &sk, &buf_size, uargs->buf);
 
     /*
      * In the origin implementation an overflow is handled by returning a
      * search header with a len of zero, so reset ret.
      */
     if (ret == -EOVERFLOW)
         ret = 0;
 
     if (ret == 0 && copy_to_user(&uargs->key, &sk, sizeof(sk)))
         ret = -EFAULT;
     return ret;
 }
 
 static noinline int btrfs_ioctl_tree_search_v2(struct inode *inode,
                            void __user *argp)
 {
     struct btrfs_ioctl_search_args_v2 __user *uarg = argp;
     struct btrfs_ioctl_search_args_v2 args;
     int ret;
     size_t buf_size;
     const size_t buf_limit = SZ_16M;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     /* copy search header and buffer size */
     if (copy_from_user(&args, uarg, sizeof(args)))
         return -EFAULT;
 
     buf_size = args.buf_size;
 
     /* limit result size to 16MB */
     if (buf_size > buf_limit)
         buf_size = buf_limit;
 
     ret = search_ioctl(inode, &args.key, &buf_size,
                (char __user *)(&uarg->buf[0]));
     if (ret == 0 && copy_to_user(&uarg->key, &args.key, sizeof(args.key)))
         ret = -EFAULT;
     else if (ret == -EOVERFLOW &&
         copy_to_user(&uarg->buf_size, &buf_size, sizeof(buf_size)))
         ret = -EFAULT;
 
     return ret;
 }
 
 /*
  * Search INODE_REFs to identify path name of 'dirid' directory
  * in a 'tree_id' tree. and sets path name to 'name'.
  */
 static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
                 u64 tree_id, u64 dirid, char *name)
 {
     struct btrfs_root *root;
     struct btrfs_key key;
     char *ptr;
     int ret = -1;
     int slot;
     int len;
     int total_len = 0;
     struct btrfs_inode_ref *iref;
     struct extent_buffer *l;
     struct btrfs_path *path;
 
     if (dirid == BTRFS_FIRST_FREE_OBJECTID) {
         name[0]='\0';
         return 0;
     }
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     ptr = &name[BTRFS_INO_LOOKUP_PATH_MAX - 1];
 
     root = btrfs_get_fs_root(info, tree_id, true);
     if (IS_ERR(root)) {
         ret = PTR_ERR(root);
         root = NULL;
         goto out;
     }
 
     key.objectid = dirid;
     key.type = BTRFS_INODE_REF_KEY;
     key.offset = (u64)-1;
 
     while (1) {
         ret = btrfs_search_backwards(root, &key, path);
         if (ret < 0)
             goto out;
         else if (ret > 0) {
             ret = -ENOENT;
             goto out;
         }
 
         l = path->nodes[0];
         slot = path->slots[0];
 
         iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);
         len = btrfs_inode_ref_name_len(l, iref);
         ptr -= len + 1;
         total_len += len + 1;
         if (ptr < name) {
             ret = -ENAMETOOLONG;
             goto out;
         }
 
         *(ptr + len) = '/';
         read_extent_buffer(l, ptr, (unsigned long)(iref + 1), len);
 
         if (key.offset == BTRFS_FIRST_FREE_OBJECTID)
             break;
 
         btrfs_release_path(path);
         key.objectid = key.offset;
         key.offset = (u64)-1;
         dirid = key.objectid;
     }
     memmove(name, ptr, total_len);
     name[total_len] = '\0';
     ret = 0;
 out:
     btrfs_put_root(root);
     btrfs_free_path(path);
     return ret;
 }
 
 static int btrfs_search_path_in_tree_user(struct user_namespace *mnt_userns,
                 struct inode *inode,
                 struct btrfs_ioctl_ino_lookup_user_args *args)
 {
     struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
     struct super_block *sb = inode->i_sb;
     struct btrfs_key upper_limit = BTRFS_I(inode)->location;
     u64 treeid = BTRFS_I(inode)->root->root_key.objectid;
     u64 dirid = args->dirid;
     unsigned long item_off;
     unsigned long item_len;
     struct btrfs_inode_ref *iref;
     struct btrfs_root_ref *rref;
     struct btrfs_root *root = NULL;
     struct btrfs_path *path;
     struct btrfs_key key, key2;
     struct extent_buffer *leaf;
     struct inode *temp_inode;
     char *ptr;
     int slot;
     int len;
     int total_len = 0;
     int ret;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     /*
      * If the bottom subvolume does not exist directly under upper_limit,
      * construct the path in from the bottom up.
      */
     if (dirid != upper_limit.objectid) {
         ptr = &args->path[BTRFS_INO_LOOKUP_USER_PATH_MAX - 1];
 
         root = btrfs_get_fs_root(fs_info, treeid, true);
         if (IS_ERR(root)) {
             ret = PTR_ERR(root);
             goto out;
         }
 
         key.objectid = dirid;
         key.type = BTRFS_INODE_REF_KEY;
         key.offset = (u64)-1;
         while (1) {
             ret = btrfs_search_backwards(root, &key, path);
             if (ret < 0)
                 goto out_put;
             else if (ret > 0) {
                 ret = -ENOENT;
                 goto out_put;
             }
 
             leaf = path->nodes[0];
             slot = path->slots[0];
 
             iref = btrfs_item_ptr(leaf, slot, struct btrfs_inode_ref);
             len = btrfs_inode_ref_name_len(leaf, iref);
             ptr -= len + 1;
             total_len += len + 1;
             if (ptr < args->path) {
                 ret = -ENAMETOOLONG;
                 goto out_put;
             }
 
             *(ptr + len) = '/';
             read_extent_buffer(leaf, ptr,
                     (unsigned long)(iref + 1), len);
 
             /* Check the read+exec permission of this directory */
             ret = btrfs_previous_item(root, path, dirid,
                           BTRFS_INODE_ITEM_KEY);
             if (ret < 0) {
                 goto out_put;
             } else if (ret > 0) {
                 ret = -ENOENT;
                 goto out_put;
             }
 
             leaf = path->nodes[0];
             slot = path->slots[0];
             btrfs_item_key_to_cpu(leaf, &key2, slot);
             if (key2.objectid != dirid) {
                 ret = -ENOENT;
                 goto out_put;
             }
 
             temp_inode = btrfs_iget(sb, key2.objectid, root);
             if (IS_ERR(temp_inode)) {
                 ret = PTR_ERR(temp_inode);
                 goto out_put;
             }
             ret = inode_permission(mnt_userns, temp_inode,
                            MAY_READ | MAY_EXEC);
             iput(temp_inode);
             if (ret) {
                 ret = -EACCES;
                 goto out_put;
             }
 
             if (key.offset == upper_limit.objectid)
                 break;
             if (key.objectid == BTRFS_FIRST_FREE_OBJECTID) {
                 ret = -EACCES;
                 goto out_put;
             }
 
             btrfs_release_path(path);
             key.objectid = key.offset;
             key.offset = (u64)-1;
             dirid = key.objectid;
         }
 
         memmove(args->path, ptr, total_len);
         args->path[total_len] = '\0';
         btrfs_put_root(root);
         root = NULL;
         btrfs_release_path(path);
     }
 
     /* Get the bottom subvolume's name from ROOT_REF */
     key.objectid = treeid;
     key.type = BTRFS_ROOT_REF_KEY;
     key.offset = args->treeid;
     ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
     if (ret < 0) {
         goto out;
     } else if (ret > 0) {
         ret = -ENOENT;
         goto out;
     }
 
     leaf = path->nodes[0];
     slot = path->slots[0];
     btrfs_item_key_to_cpu(leaf, &key, slot);
 
     item_off = btrfs_item_ptr_offset(leaf, slot);
     item_len = btrfs_item_size(leaf, slot);
     /* Check if dirid in ROOT_REF corresponds to passed dirid */
     rref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
     if (args->dirid != btrfs_root_ref_dirid(leaf, rref)) {
         ret = -EINVAL;
         goto out;
     }
 
     /* Copy subvolume's name */
     item_off += sizeof(struct btrfs_root_ref);
     item_len -= sizeof(struct btrfs_root_ref);
     read_extent_buffer(leaf, args->name, item_off, item_len);
     args->name[item_len] = 0;
 
 out_put:
     btrfs_put_root(root);
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static noinline int btrfs_ioctl_ino_lookup(struct btrfs_root *root,
                        void __user *argp)
 {
     struct btrfs_ioctl_ino_lookup_args *args;
     int ret = 0;
 
     args = memdup_user(argp, sizeof(*args));
     if (IS_ERR(args))
         return PTR_ERR(args);
 
     /*
      * Unprivileged query to obtain the containing subvolume root id. The
      * path is reset so it's consistent with btrfs_search_path_in_tree.
      */
     if (args->treeid == 0)
         args->treeid = root->root_key.objectid;
 
     if (args->objectid == BTRFS_FIRST_FREE_OBJECTID) {
         args->name[0] = 0;
         goto out;
     }
 
     if (!capable(CAP_SYS_ADMIN)) {
         ret = -EPERM;
         goto out;
     }
 
     ret = btrfs_search_path_in_tree(root->fs_info,
                     args->treeid, args->objectid,
                     args->name);
 
 out:
     if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
         ret = -EFAULT;
 
     kfree(args);
     return ret;
 }
 
 /*
  * Version of ino_lookup ioctl (unprivileged)
  *
  * The main differences from ino_lookup ioctl are:
  *
  *   1. Read + Exec permission will be checked using inode_permission() during
  *      path construction. -EACCES will be returned in case of failure.
  *   2. Path construction will be stopped at the inode number which corresponds
  *      to the fd with which this ioctl is called. If constructed path does not
  *      exist under fd's inode, -EACCES will be returned.
  *   3. The name of bottom subvolume is also searched and filled.
  */
 static int btrfs_ioctl_ino_lookup_user(struct file *file, void __user *argp)
 {
     struct btrfs_ioctl_ino_lookup_user_args *args;
     struct inode *inode;
     int ret;
 
     args = memdup_user(argp, sizeof(*args));
     if (IS_ERR(args))
         return PTR_ERR(args);
 
     inode = file_inode(file);
 
     if (args->dirid == BTRFS_FIRST_FREE_OBJECTID &&
         BTRFS_I(inode)->location.objectid != BTRFS_FIRST_FREE_OBJECTID) {
         /*
          * The subvolume does not exist under fd with which this is
          * called
          */
         kfree(args);
         return -EACCES;
     }
 
     ret = btrfs_search_path_in_tree_user(file_mnt_user_ns(file), inode, args);
 
     if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
         ret = -EFAULT;
 
     kfree(args);
     return ret;
 }
 
 /* Get the subvolume information in BTRFS_ROOT_ITEM and BTRFS_ROOT_BACKREF */
 static int btrfs_ioctl_get_subvol_info(struct inode *inode, void __user *argp)
 {
     struct btrfs_ioctl_get_subvol_info_args *subvol_info;
     struct btrfs_fs_info *fs_info;
     struct btrfs_root *root;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct btrfs_root_item *root_item;
     struct btrfs_root_ref *rref;
     struct extent_buffer *leaf;
     unsigned long item_off;
     unsigned long item_len;
     int slot;
     int ret = 0;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     subvol_info = kzalloc(sizeof(*subvol_info), GFP_KERNEL);
     if (!subvol_info) {
         btrfs_free_path(path);
         return -ENOMEM;
     }
 
     fs_info = BTRFS_I(inode)->root->fs_info;
 
     /* Get root_item of inode's subvolume */
     key.objectid = BTRFS_I(inode)->root->root_key.objectid;
     root = btrfs_get_fs_root(fs_info, key.objectid, true);
     if (IS_ERR(root)) {
         ret = PTR_ERR(root);
         goto out_free;
     }
     root_item = &root->root_item;
 
     subvol_info->treeid = key.objectid;
 
     subvol_info->generation = btrfs_root_generation(root_item);
     subvol_info->flags = btrfs_root_flags(root_item);
 
     memcpy(subvol_info->uuid, root_item->uuid, BTRFS_UUID_SIZE);
     memcpy(subvol_info->parent_uuid, root_item->parent_uuid,
                             BTRFS_UUID_SIZE);
     memcpy(subvol_info->received_uuid, root_item->received_uuid,
                             BTRFS_UUID_SIZE);
 
     subvol_info->ctransid = btrfs_root_ctransid(root_item);
     subvol_info->ctime.sec = btrfs_stack_timespec_sec(&root_item->ctime);
     subvol_info->ctime.nsec = btrfs_stack_timespec_nsec(&root_item->ctime);
 
     subvol_info->otransid = btrfs_root_otransid(root_item);
     subvol_info->otime.sec = btrfs_stack_timespec_sec(&root_item->otime);
     subvol_info->otime.nsec = btrfs_stack_timespec_nsec(&root_item->otime);
 
     subvol_info->stransid = btrfs_root_stransid(root_item);
     subvol_info->stime.sec = btrfs_stack_timespec_sec(&root_item->stime);
     subvol_info->stime.nsec = btrfs_stack_timespec_nsec(&root_item->stime);
 
     subvol_info->rtransid = btrfs_root_rtransid(root_item);
     subvol_info->rtime.sec = btrfs_stack_timespec_sec(&root_item->rtime);
     subvol_info->rtime.nsec = btrfs_stack_timespec_nsec(&root_item->rtime);
 
     if (key.objectid != BTRFS_FS_TREE_OBJECTID) {
         /* Search root tree for ROOT_BACKREF of this subvolume */
         key.type = BTRFS_ROOT_BACKREF_KEY;
         key.offset = 0;
         ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
         if (ret < 0) {
             goto out;
         } else if (path->slots[0] >=
                btrfs_header_nritems(path->nodes[0])) {
             ret = btrfs_next_leaf(fs_info->tree_root, path);
             if (ret < 0) {
                 goto out;
             } else if (ret > 0) {
                 ret = -EUCLEAN;
                 goto out;
             }
         }
 
         leaf = path->nodes[0];
         slot = path->slots[0];
         btrfs_item_key_to_cpu(leaf, &key, slot);
         if (key.objectid == subvol_info->treeid &&
             key.type == BTRFS_ROOT_BACKREF_KEY) {
             subvol_info->parent_id = key.offset;
 
             rref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
             subvol_info->dirid = btrfs_root_ref_dirid(leaf, rref);
 
             item_off = btrfs_item_ptr_offset(leaf, slot)
                     + sizeof(struct btrfs_root_ref);
             item_len = btrfs_item_size(leaf, slot)
                     - sizeof(struct btrfs_root_ref);
             read_extent_buffer(leaf, subvol_info->name,
                        item_off, item_len);
         } else {
             ret = -ENOENT;
             goto out;
         }
     }
 
     if (copy_to_user(argp, subvol_info, sizeof(*subvol_info)))
         ret = -EFAULT;
 
 out:
     btrfs_put_root(root);
 out_free:
     btrfs_free_path(path);
     kfree(subvol_info);
     return ret;
 }
 
 /*
  * Return ROOT_REF information of the subvolume containing this inode
  * except the subvolume name.
  */
 static int btrfs_ioctl_get_subvol_rootref(struct btrfs_root *root,
                       void __user *argp)
 {
     struct btrfs_ioctl_get_subvol_rootref_args *rootrefs;
     struct btrfs_root_ref *rref;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct extent_buffer *leaf;
     u64 objectid;
     int slot;
     int ret;
     u8 found;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     rootrefs = memdup_user(argp, sizeof(*rootrefs));
     if (IS_ERR(rootrefs)) {
         btrfs_free_path(path);
         return PTR_ERR(rootrefs);
     }
 
     objectid = root->root_key.objectid;
     key.objectid = objectid;
     key.type = BTRFS_ROOT_REF_KEY;
     key.offset = rootrefs->min_treeid;
     found = 0;
 
     root = root->fs_info->tree_root;
     ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
     if (ret < 0) {
         goto out;
     } else if (path->slots[0] >=
            btrfs_header_nritems(path->nodes[0])) {
         ret = btrfs_next_leaf(root, path);
         if (ret < 0) {
             goto out;
         } else if (ret > 0) {
             ret = -EUCLEAN;
             goto out;
         }
     }
     while (1) {
         leaf = path->nodes[0];
         slot = path->slots[0];
 
         btrfs_item_key_to_cpu(leaf, &key, slot);
         if (key.objectid != objectid || key.type != BTRFS_ROOT_REF_KEY) {
             ret = 0;
             goto out;
         }
 
         if (found == BTRFS_MAX_ROOTREF_BUFFER_NUM) {
             ret = -EOVERFLOW;
             goto out;
         }
 
         rref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
         rootrefs->rootref[found].treeid = key.offset;
         rootrefs->rootref[found].dirid =
                   btrfs_root_ref_dirid(leaf, rref);
         found++;
 
         ret = btrfs_next_item(root, path);
         if (ret < 0) {
             goto out;
         } else if (ret > 0) {
             ret = -EUCLEAN;
             goto out;
         }
     }
 
 out:
     if (!ret || ret == -EOVERFLOW) {
         rootrefs->num_items = found;
         /* update min_treeid for next search */
         if (found)
             rootrefs->min_treeid =
                 rootrefs->rootref[found - 1].treeid + 1;
         if (copy_to_user(argp, rootrefs, sizeof(*rootrefs)))
             ret = -EFAULT;
     }
 
     kfree(rootrefs);
     btrfs_free_path(path);
 
     return ret;
 }
 
 static noinline int btrfs_ioctl_snap_destroy(struct file *file,
                          void __user *arg,
                          bool destroy_v2)
 {
     struct dentry *parent = file->f_path.dentry;
     struct btrfs_fs_info *fs_info = btrfs_sb(parent->d_sb);
     struct dentry *dentry;
     struct inode *dir = d_inode(parent);
     struct inode *inode;
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct btrfs_root *dest = NULL;
     struct btrfs_ioctl_vol_args *vol_args = NULL;
     struct btrfs_ioctl_vol_args_v2 *vol_args2 = NULL;
     struct user_namespace *mnt_userns = file_mnt_user_ns(file);
     char *subvol_name, *subvol_name_ptr = NULL;
     int subvol_namelen;
     int err = 0;
     bool destroy_parent = false;
 
     /* We don't support snapshots with extent tree v2 yet. */
     if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
         btrfs_err(fs_info,
               "extent tree v2 doesn't support snapshot deletion yet");
         return -EOPNOTSUPP;
     }
 
     if (destroy_v2) {
         vol_args2 = memdup_user(arg, sizeof(*vol_args2));
         if (IS_ERR(vol_args2))
             return PTR_ERR(vol_args2);
 
         if (vol_args2->flags & ~BTRFS_SUBVOL_DELETE_ARGS_MASK) {
             err = -EOPNOTSUPP;
             goto out;
         }
 
         /*
          * If SPEC_BY_ID is not set, we are looking for the subvolume by
          * name, same as v1 currently does.
          */
         if (!(vol_args2->flags & BTRFS_SUBVOL_SPEC_BY_ID)) {
             vol_args2->name[BTRFS_SUBVOL_NAME_MAX] = 0;
             subvol_name = vol_args2->name;
 
             err = mnt_want_write_file(file);
             if (err)
                 goto out;
         } else {
             struct inode *old_dir;
 
             if (vol_args2->subvolid < BTRFS_FIRST_FREE_OBJECTID) {
                 err = -EINVAL;
                 goto out;
             }
 
             err = mnt_want_write_file(file);
             if (err)
                 goto out;
 
             dentry = btrfs_get_dentry(fs_info->sb,
                     BTRFS_FIRST_FREE_OBJECTID,
                     vol_args2->subvolid, 0, 0);
             if (IS_ERR(dentry)) {
                 err = PTR_ERR(dentry);
                 goto out_drop_write;
             }
 
             /*
              * Change the default parent since the subvolume being
              * deleted can be outside of the current mount point.
              */
             parent = btrfs_get_parent(dentry);
 
             /*
              * At this point dentry->d_name can point to '/' if the
              * subvolume we want to destroy is outsite of the
              * current mount point, so we need to release the
              * current dentry and execute the lookup to return a new
              * one with ->d_name pointing to the
              * <mount point>/subvol_name.
              */
             dput(dentry);
             if (IS_ERR(parent)) {
                 err = PTR_ERR(parent);
                 goto out_drop_write;
             }
             old_dir = dir;
             dir = d_inode(parent);
 
             /*
              * If v2 was used with SPEC_BY_ID, a new parent was
              * allocated since the subvolume can be outside of the
              * current mount point. Later on we need to release this
              * new parent dentry.
              */
             destroy_parent = true;
 
             /*
              * On idmapped mounts, deletion via subvolid is
              * restricted to subvolumes that are immediate
              * ancestors of the inode referenced by the file
              * descriptor in the ioctl. Otherwise the idmapping
              * could potentially be abused to delete subvolumes
              * anywhere in the filesystem the user wouldn't be able
              * to delete without an idmapped mount.
              */
             if (old_dir != dir && mnt_userns != &init_user_ns) {
                 err = -EOPNOTSUPP;
                 goto free_parent;
             }
 
             subvol_name_ptr = btrfs_get_subvol_name_from_objectid(
                         fs_info, vol_args2->subvolid);
             if (IS_ERR(subvol_name_ptr)) {
                 err = PTR_ERR(subvol_name_ptr);
                 goto free_parent;
             }
             /* subvol_name_ptr is already nul terminated */
             subvol_name = (char *)kbasename(subvol_name_ptr);
         }
     } else {
         vol_args = memdup_user(arg, sizeof(*vol_args));
         if (IS_ERR(vol_args))
             return PTR_ERR(vol_args);
 
         vol_args->name[BTRFS_PATH_NAME_MAX] = 0;
         subvol_name = vol_args->name;
 
         err = mnt_want_write_file(file);
         if (err)
             goto out;
     }
 
     subvol_namelen = strlen(subvol_name);
 
     if (strchr(subvol_name, '/') ||
         strncmp(subvol_name, "..", subvol_namelen) == 0) {
         err = -EINVAL;
         goto free_subvol_name;
     }
 
     if (!S_ISDIR(dir->i_mode)) {
         err = -ENOTDIR;
         goto free_subvol_name;
     }
 
     err = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
     if (err == -EINTR)
         goto free_subvol_name;
     dentry = lookup_one(mnt_userns, subvol_name, parent, subvol_namelen);
     if (IS_ERR(dentry)) {
         err = PTR_ERR(dentry);
         goto out_unlock_dir;
     }
 
     if (d_really_is_negative(dentry)) {
         err = -ENOENT;
         goto out_dput;
     }
 
     inode = d_inode(dentry);
     dest = BTRFS_I(inode)->root;
     if (!capable(CAP_SYS_ADMIN)) {
         /*
          * Regular user.  Only allow this with a special mount
          * option, when the user has write+exec access to the
          * subvol root, and when rmdir(2) would have been
          * allowed.
          *
          * Note that this is _not_ check that the subvol is
          * empty or doesn't contain data that we wouldn't
          * otherwise be able to delete.
          *
          * Users who want to delete empty subvols should try
          * rmdir(2).
          */
         err = -EPERM;
         if (!btrfs_test_opt(fs_info, USER_SUBVOL_RM_ALLOWED))
             goto out_dput;
 
         /*
          * Do not allow deletion if the parent dir is the same
          * as the dir to be deleted.  That means the ioctl
          * must be called on the dentry referencing the root
          * of the subvol, not a random directory contained
          * within it.
          */
         err = -EINVAL;
         if (root == dest)
             goto out_dput;
 
         err = inode_permission(mnt_userns, inode, MAY_WRITE | MAY_EXEC);
         if (err)
             goto out_dput;
     }
 
     /* check if subvolume may be deleted by a user */
     err = btrfs_may_delete(mnt_userns, dir, dentry, 1);
     if (err)
         goto out_dput;
 
     if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
         err = -EINVAL;
         goto out_dput;
     }
 
     btrfs_inode_lock(inode, 0);
     err = btrfs_delete_subvolume(dir, dentry);
     btrfs_inode_unlock(inode, 0);
     if (!err)
         d_delete_notify(dir, dentry);
 
 out_dput:
     dput(dentry);
 out_unlock_dir:
     btrfs_inode_unlock(dir, 0);
 free_subvol_name:
     kfree(subvol_name_ptr);
 free_parent:
     if (destroy_parent)
         dput(parent);
 out_drop_write:
     mnt_drop_write_file(file);
 out:
     kfree(vol_args2);
     kfree(vol_args);
     return err;
 }
 
 static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_ioctl_defrag_range_args range = {0};
     int ret;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     if (btrfs_root_readonly(root)) {
         ret = -EROFS;
         goto out;
     }
 
     switch (inode->i_mode & S_IFMT) {
     case S_IFDIR:
         if (!capable(CAP_SYS_ADMIN)) {
             ret = -EPERM;
             goto out;
         }
         ret = btrfs_defrag_root(root);
         break;
     case S_IFREG:
         /*
          * Note that this does not check the file descriptor for write
          * access. This prevents defragmenting executables that are
          * running and allows defrag on files open in read-only mode.
          */
         if (!capable(CAP_SYS_ADMIN) &&
             inode_permission(&init_user_ns, inode, MAY_WRITE)) {
             ret = -EPERM;
             goto out;
         }
 
         if (argp) {
             if (copy_from_user(&range, argp, sizeof(range))) {
                 ret = -EFAULT;
                 goto out;
             }
             /* compression requires us to start the IO */
             if ((range.flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
                 range.flags |= BTRFS_DEFRAG_RANGE_START_IO;
                 range.extent_thresh = (u32)-1;
             }
         } else {
             /* the rest are all set to zero by kzalloc */
             range.len = (u64)-1;
         }
         ret = btrfs_defrag_file(file_inode(file), &file->f_ra,
                     &range, BTRFS_OLDEST_GENERATION, 0);
         if (ret > 0)
             ret = 0;
         break;
     default:
         ret = -EINVAL;
     }
 out:
     mnt_drop_write_file(file);
     return ret;
 }
 
 static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)
 {
     struct btrfs_ioctl_vol_args *vol_args;
     bool restore_op = false;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
         btrfs_err(fs_info, "device add not supported on extent tree v2 yet");
         return -EINVAL;
     }
 
     if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_ADD)) {
         if (!btrfs_exclop_start_try_lock(fs_info, BTRFS_EXCLOP_DEV_ADD))
             return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
 
         /*
          * We can do the device add because we have a paused balanced,
          * change the exclusive op type and remember we should bring
          * back the paused balance
          */
         fs_info->exclusive_operation = BTRFS_EXCLOP_DEV_ADD;
         btrfs_exclop_start_unlock(fs_info);
         restore_op = true;
     }
 
     vol_args = memdup_user(arg, sizeof(*vol_args));
     if (IS_ERR(vol_args)) {
         ret = PTR_ERR(vol_args);
         goto out;
     }
 
     vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
     ret = btrfs_init_new_device(fs_info, vol_args->name);
 
     if (!ret)
         btrfs_info(fs_info, "disk added %s", vol_args->name);
 
     kfree(vol_args);
 out:
     if (restore_op)
         btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE_PAUSED);
     else
         btrfs_exclop_finish(fs_info);
     return ret;
 }
 
 static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
 {
     BTRFS_DEV_LOOKUP_ARGS(args);
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_ioctl_vol_args_v2 *vol_args;
     struct block_device *bdev = NULL;
     fmode_t mode;
     int ret;
     bool cancel = false;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     vol_args = memdup_user(arg, sizeof(*vol_args));
     if (IS_ERR(vol_args))
         return PTR_ERR(vol_args);
 
     if (vol_args->flags & ~BTRFS_DEVICE_REMOVE_ARGS_MASK) {
         ret = -EOPNOTSUPP;
         goto out;
     }
 
     vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
     if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID) {
         args.devid = vol_args->devid;
     } else if (!strcmp("cancel", vol_args->name)) {
         cancel = true;
     } else {
         ret = btrfs_get_dev_args_from_path(fs_info, &args, vol_args->name);
         if (ret)
             goto out;
     }
 
     ret = mnt_want_write_file(file);
     if (ret)
         goto out;
 
     ret = exclop_start_or_cancel_reloc(fs_info, BTRFS_EXCLOP_DEV_REMOVE,
                        cancel);
     if (ret)
         goto err_drop;
 
     /* Exclusive operation is now claimed */
     ret = btrfs_rm_device(fs_info, &args, &bdev, &mode);
 
     btrfs_exclop_finish(fs_info);
 
     if (!ret) {
         if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID)
             btrfs_info(fs_info, "device deleted: id %llu",
                     vol_args->devid);
         else
             btrfs_info(fs_info, "device deleted: %s",
                     vol_args->name);
     }
 err_drop:
     mnt_drop_write_file(file);
     if (bdev)
         blkdev_put(bdev, mode);
 out:
     btrfs_put_dev_args_from_path(&args);
     kfree(vol_args);
     return ret;
 }
 
 static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
 {
     BTRFS_DEV_LOOKUP_ARGS(args);
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_ioctl_vol_args *vol_args;
     struct block_device *bdev = NULL;
     fmode_t mode;
     int ret;
     bool cancel = false;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     vol_args = memdup_user(arg, sizeof(*vol_args));
     if (IS_ERR(vol_args))
         return PTR_ERR(vol_args);
 
     vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
     if (!strcmp("cancel", vol_args->name)) {
         cancel = true;
     } else {
         ret = btrfs_get_dev_args_from_path(fs_info, &args, vol_args->name);
         if (ret)
             goto out;
     }
 
     ret = mnt_want_write_file(file);
     if (ret)
         goto out;
 
     ret = exclop_start_or_cancel_reloc(fs_info, BTRFS_EXCLOP_DEV_REMOVE,
                        cancel);
     if (ret == 0) {
         ret = btrfs_rm_device(fs_info, &args, &bdev, &mode);
         if (!ret)
             btrfs_info(fs_info, "disk deleted %s", vol_args->name);
         btrfs_exclop_finish(fs_info);
     }
 
     mnt_drop_write_file(file);
     if (bdev)
         blkdev_put(bdev, mode);
 out:
     btrfs_put_dev_args_from_path(&args);
     kfree(vol_args);
     return ret;
 }
 
 static long btrfs_ioctl_fs_info(struct btrfs_fs_info *fs_info,
                 void __user *arg)
 {
     struct btrfs_ioctl_fs_info_args *fi_args;
     struct btrfs_device *device;
     struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
     u64 flags_in;
     int ret = 0;
 
     fi_args = memdup_user(arg, sizeof(*fi_args));
     if (IS_ERR(fi_args))
         return PTR_ERR(fi_args);
 
     flags_in = fi_args->flags;
     memset(fi_args, 0, sizeof(*fi_args));
 
     rcu_read_lock();
     fi_args->num_devices = fs_devices->num_devices;
 
     list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
         if (device->devid > fi_args->max_id)
             fi_args->max_id = device->devid;
     }
     rcu_read_unlock();
 
     memcpy(&fi_args->fsid, fs_devices->fsid, sizeof(fi_args->fsid));
     fi_args->nodesize = fs_info->nodesize;
     fi_args->sectorsize = fs_info->sectorsize;
     fi_args->clone_alignment = fs_info->sectorsize;
 
     if (flags_in & BTRFS_FS_INFO_FLAG_CSUM_INFO) {
         fi_args->csum_type = btrfs_super_csum_type(fs_info->super_copy);
         fi_args->csum_size = btrfs_super_csum_size(fs_info->super_copy);
         fi_args->flags |= BTRFS_FS_INFO_FLAG_CSUM_INFO;
     }
 
     if (flags_in & BTRFS_FS_INFO_FLAG_GENERATION) {
         fi_args->generation = fs_info->generation;
         fi_args->flags |= BTRFS_FS_INFO_FLAG_GENERATION;
     }
 
     if (flags_in & BTRFS_FS_INFO_FLAG_METADATA_UUID) {
         memcpy(&fi_args->metadata_uuid, fs_devices->metadata_uuid,
                sizeof(fi_args->metadata_uuid));
         fi_args->flags |= BTRFS_FS_INFO_FLAG_METADATA_UUID;
     }
 
     if (copy_to_user(arg, fi_args, sizeof(*fi_args)))
         ret = -EFAULT;
 
     kfree(fi_args);
     return ret;
 }
 
 static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
                  void __user *arg)
 {
     BTRFS_DEV_LOOKUP_ARGS(args);
     struct btrfs_ioctl_dev_info_args *di_args;
     struct btrfs_device *dev;
     int ret = 0;
 
     di_args = memdup_user(arg, sizeof(*di_args));
     if (IS_ERR(di_args))
         return PTR_ERR(di_args);
 
     args.devid = di_args->devid;
     if (!btrfs_is_empty_uuid(di_args->uuid))
         args.uuid = di_args->uuid;
 
     rcu_read_lock();
     dev = btrfs_find_device(fs_info->fs_devices, &args);
     if (!dev) {
         ret = -ENODEV;
         goto out;
     }
 
     di_args->devid = dev->devid;
     di_args->bytes_used = btrfs_device_get_bytes_used(dev);
     di_args->total_bytes = btrfs_device_get_total_bytes(dev);
     memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
     if (dev->name) {
         strncpy(di_args->path, rcu_str_deref(dev->name),
                 sizeof(di_args->path) - 1);
         di_args->path[sizeof(di_args->path) - 1] = 0;
     } else {
         di_args->path[0] = '\0';
     }
 
 out:
     rcu_read_unlock();
     if (ret == 0 && copy_to_user(arg, di_args, sizeof(*di_args)))
         ret = -EFAULT;
 
     kfree(di_args);
     return ret;
 }
 
 static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_root *new_root;
     struct btrfs_dir_item *di;
     struct btrfs_trans_handle *trans;
     struct btrfs_path *path = NULL;
     struct btrfs_disk_key disk_key;
     u64 objectid = 0;
     u64 dir_id;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     if (copy_from_user(&objectid, argp, sizeof(objectid))) {
         ret = -EFAULT;
         goto out;
     }
 
     if (!objectid)
         objectid = BTRFS_FS_TREE_OBJECTID;
 
     new_root = btrfs_get_fs_root(fs_info, objectid, true);
     if (IS_ERR(new_root)) {
         ret = PTR_ERR(new_root);
         goto out;
     }
     if (!is_fstree(new_root->root_key.objectid)) {
         ret = -ENOENT;
         goto out_free;
     }
 
     path = btrfs_alloc_path();
     if (!path) {
         ret = -ENOMEM;
         goto out_free;
     }
 
     trans = btrfs_start_transaction(root, 1);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out_free;
     }
 
     dir_id = btrfs_super_root_dir(fs_info->super_copy);
     di = btrfs_lookup_dir_item(trans, fs_info->tree_root, path,
                    dir_id, "default", 7, 1);
     if (IS_ERR_OR_NULL(di)) {
         btrfs_release_path(path);
         btrfs_end_transaction(trans);
         btrfs_err(fs_info,
               "Umm, you don't have the default diritem, this isn't going to work");
         ret = -ENOENT;
         goto out_free;
     }
 
     btrfs_cpu_key_to_disk(&disk_key, &new_root->root_key);
     btrfs_set_dir_item_key(path->nodes[0], di, &disk_key);
     btrfs_mark_buffer_dirty(path->nodes[0]);
     btrfs_release_path(path);
 
     btrfs_set_fs_incompat(fs_info, DEFAULT_SUBVOL);
     btrfs_end_transaction(trans);
 out_free:
     btrfs_put_root(new_root);
     btrfs_free_path(path);
 out:
     mnt_drop_write_file(file);
     return ret;
 }
 
 static void get_block_group_info(struct list_head *groups_list,
                  struct btrfs_ioctl_space_info *space)
 {
     struct btrfs_block_group *block_group;
 
     space->total_bytes = 0;
     space->used_bytes = 0;
     space->flags = 0;
     list_for_each_entry(block_group, groups_list, list) {
         space->flags = block_group->flags;
         space->total_bytes += block_group->length;
         space->used_bytes += block_group->used;
     }
 }
 
 static long btrfs_ioctl_space_info(struct btrfs_fs_info *fs_info,
                    void __user *arg)
 {
     struct btrfs_ioctl_space_args space_args;
     struct btrfs_ioctl_space_info space;
     struct btrfs_ioctl_space_info *dest;
     struct btrfs_ioctl_space_info *dest_orig;
     struct btrfs_ioctl_space_info __user *user_dest;
     struct btrfs_space_info *info;
     static const u64 types[] = {
         BTRFS_BLOCK_GROUP_DATA,
         BTRFS_BLOCK_GROUP_SYSTEM,
         BTRFS_BLOCK_GROUP_METADATA,
         BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA
     };
     int num_types = 4;
     int alloc_size;
     int ret = 0;
     u64 slot_count = 0;
     int i, c;
 
     if (copy_from_user(&space_args,
                (struct btrfs_ioctl_space_args __user *)arg,
                sizeof(space_args)))
         return -EFAULT;
 
     for (i = 0; i < num_types; i++) {
         struct btrfs_space_info *tmp;
 
         info = NULL;
         list_for_each_entry(tmp, &fs_info->space_info, list) {
             if (tmp->flags == types[i]) {
                 info = tmp;
                 break;
             }
         }
 
         if (!info)
             continue;
 
         down_read(&info->groups_sem);
         for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
             if (!list_empty(&info->block_groups[c]))
                 slot_count++;
         }
         up_read(&info->groups_sem);
     }
 
     /*
      * Global block reserve, exported as a space_info
      */
     slot_count++;
 
     /* space_slots == 0 means they are asking for a count */
     if (space_args.space_slots == 0) {
         space_args.total_spaces = slot_count;
         goto out;
     }
 
     slot_count = min_t(u64, space_args.space_slots, slot_count);
 
     alloc_size = sizeof(*dest) * slot_count;
 
     /* we generally have at most 6 or so space infos, one for each raid
      * level.  So, a whole page should be more than enough for everyone
      */
     if (alloc_size > PAGE_SIZE)
         return -ENOMEM;
 
     space_args.total_spaces = 0;
     dest = kmalloc(alloc_size, GFP_KERNEL);
     if (!dest)
         return -ENOMEM;
     dest_orig = dest;
 
     /* now we have a buffer to copy into */
     for (i = 0; i < num_types; i++) {
         struct btrfs_space_info *tmp;
 
         if (!slot_count)
             break;
 
         info = NULL;
         list_for_each_entry(tmp, &fs_info->space_info, list) {
             if (tmp->flags == types[i]) {
                 info = tmp;
                 break;
             }
         }
 
         if (!info)
             continue;
         down_read(&info->groups_sem);
         for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
             if (!list_empty(&info->block_groups[c])) {
                 get_block_group_info(&info->block_groups[c],
                              &space);
                 memcpy(dest, &space, sizeof(space));
                 dest++;
                 space_args.total_spaces++;
                 slot_count--;
             }
             if (!slot_count)
                 break;
         }
         up_read(&info->groups_sem);
     }
 
     /*
      * Add global block reserve
      */
     if (slot_count) {
         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
 
         spin_lock(&block_rsv->lock);
         space.total_bytes = block_rsv->size;
         space.used_bytes = block_rsv->size - block_rsv->reserved;
         spin_unlock(&block_rsv->lock);
         space.flags = BTRFS_SPACE_INFO_GLOBAL_RSV;
         memcpy(dest, &space, sizeof(space));
         space_args.total_spaces++;
     }
 
     user_dest = (struct btrfs_ioctl_space_info __user *)
         (arg + sizeof(struct btrfs_ioctl_space_args));
 
     if (copy_to_user(user_dest, dest_orig, alloc_size))
         ret = -EFAULT;
 
     kfree(dest_orig);
 out:
     if (ret == 0 && copy_to_user(arg, &space_args, sizeof(space_args)))
         ret = -EFAULT;
 
     return ret;
 }
 
 static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
                         void __user *argp)
 {
     struct btrfs_trans_handle *trans;
     u64 transid;
 
     trans = btrfs_attach_transaction_barrier(root);
     if (IS_ERR(trans)) {
         if (PTR_ERR(trans) != -ENOENT)
             return PTR_ERR(trans);
 
         /* No running transaction, don't bother */
         transid = root->fs_info->last_trans_committed;
         goto out;
     }
     transid = trans->transid;
     btrfs_commit_transaction_async(trans);
 out:
     if (argp)
         if (copy_to_user(argp, &transid, sizeof(transid)))
             return -EFAULT;
     return 0;
 }
 
 static noinline long btrfs_ioctl_wait_sync(struct btrfs_fs_info *fs_info,
                        void __user *argp)
 {
     u64 transid;
 
     if (argp) {
         if (copy_from_user(&transid, argp, sizeof(transid)))
             return -EFAULT;
     } else {
         transid = 0;  /* current trans */
     }
     return btrfs_wait_for_commit(fs_info, transid);
 }
 
 static long btrfs_ioctl_scrub(struct file *file, void __user *arg)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(file_inode(file)->i_sb);
     struct btrfs_ioctl_scrub_args *sa;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
         btrfs_err(fs_info, "scrub is not supported on extent tree v2 yet");
         return -EINVAL;
     }
 
     sa = memdup_user(arg, sizeof(*sa));
     if (IS_ERR(sa))
         return PTR_ERR(sa);
 
     if (!(sa->flags & BTRFS_SCRUB_READONLY)) {
         ret = mnt_want_write_file(file);
         if (ret)
             goto out;
     }
 
     ret = btrfs_scrub_dev(fs_info, sa->devid, sa->start, sa->end,
                   &sa->progress, sa->flags & BTRFS_SCRUB_READONLY,
                   0);
 
     /*
      * Copy scrub args to user space even if btrfs_scrub_dev() returned an
      * error. This is important as it allows user space to know how much
      * progress scrub has done. For example, if scrub is canceled we get
      * -ECANCELED from btrfs_scrub_dev() and return that error back to user
      * space. Later user space can inspect the progress from the structure
      * btrfs_ioctl_scrub_args and resume scrub from where it left off
      * previously (btrfs-progs does this).
      * If we fail to copy the btrfs_ioctl_scrub_args structure to user space
      * then return -EFAULT to signal the structure was not copied or it may
      * be corrupt and unreliable due to a partial copy.
      */
     if (copy_to_user(arg, sa, sizeof(*sa)))
         ret = -EFAULT;
 
     if (!(sa->flags & BTRFS_SCRUB_READONLY))
         mnt_drop_write_file(file);
 out:
     kfree(sa);
     return ret;
 }
 
 static long btrfs_ioctl_scrub_cancel(struct btrfs_fs_info *fs_info)
 {
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     return btrfs_scrub_cancel(fs_info);
 }
 
 static long btrfs_ioctl_scrub_progress(struct btrfs_fs_info *fs_info,
                        void __user *arg)
 {
     struct btrfs_ioctl_scrub_args *sa;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     sa = memdup_user(arg, sizeof(*sa));
     if (IS_ERR(sa))
         return PTR_ERR(sa);
 
     ret = btrfs_scrub_progress(fs_info, sa->devid, &sa->progress);
 
     if (ret == 0 && copy_to_user(arg, sa, sizeof(*sa)))
         ret = -EFAULT;
 
     kfree(sa);
     return ret;
 }
 
 static long btrfs_ioctl_get_dev_stats(struct btrfs_fs_info *fs_info,
                       void __user *arg)
 {
     struct btrfs_ioctl_get_dev_stats *sa;
     int ret;
 
     sa = memdup_user(arg, sizeof(*sa));
     if (IS_ERR(sa))
         return PTR_ERR(sa);
 
     if ((sa->flags & BTRFS_DEV_STATS_RESET) && !capable(CAP_SYS_ADMIN)) {
         kfree(sa);
         return -EPERM;
     }
 
     ret = btrfs_get_dev_stats(fs_info, sa);
 
     if (ret == 0 && copy_to_user(arg, sa, sizeof(*sa)))
         ret = -EFAULT;
 
     kfree(sa);
     return ret;
 }
 
 static long btrfs_ioctl_dev_replace(struct btrfs_fs_info *fs_info,
                     void __user *arg)
 {
     struct btrfs_ioctl_dev_replace_args *p;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
         btrfs_err(fs_info, "device replace not supported on extent tree v2 yet");
         return -EINVAL;
     }
 
     p = memdup_user(arg, sizeof(*p));
     if (IS_ERR(p))
         return PTR_ERR(p);
 
     switch (p->cmd) {
     case BTRFS_IOCTL_DEV_REPLACE_CMD_START:
         if (sb_rdonly(fs_info->sb)) {
             ret = -EROFS;
             goto out;
         }
         if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
             ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
         } else {
             ret = btrfs_dev_replace_by_ioctl(fs_info, p);
             btrfs_exclop_finish(fs_info);
         }
         break;
     case BTRFS_IOCTL_DEV_REPLACE_CMD_STATUS:
         btrfs_dev_replace_status(fs_info, p);
         ret = 0;
         break;
     case BTRFS_IOCTL_DEV_REPLACE_CMD_CANCEL:
         p->result = btrfs_dev_replace_cancel(fs_info);
         ret = 0;
         break;
     default:
         ret = -EINVAL;
         break;
     }
 
     if ((ret == 0 || ret == -ECANCELED) && copy_to_user(arg, p, sizeof(*p)))
         ret = -EFAULT;
 out:
     kfree(p);
     return ret;
 }
 
 static long btrfs_ioctl_ino_to_path(struct btrfs_root *root, void __user *arg)
 {
     int ret = 0;
     int i;
     u64 rel_ptr;
     int size;
     struct btrfs_ioctl_ino_path_args *ipa = NULL;
     struct inode_fs_paths *ipath = NULL;
     struct btrfs_path *path;
 
     if (!capable(CAP_DAC_READ_SEARCH))
         return -EPERM;
 
     path = btrfs_alloc_path();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
 
     ipa = memdup_user(arg, sizeof(*ipa));
     if (IS_ERR(ipa)) {
         ret = PTR_ERR(ipa);
         ipa = NULL;
         goto out;
     }
 
     size = min_t(u32, ipa->size, 4096);
     ipath = init_ipath(size, root, path);
     if (IS_ERR(ipath)) {
         ret = PTR_ERR(ipath);
         ipath = NULL;
         goto out;
     }
 
     ret = paths_from_inode(ipa->inum, ipath);
     if (ret < 0)
         goto out;
 
     for (i = 0; i < ipath->fspath->elem_cnt; ++i) {
         rel_ptr = ipath->fspath->val[i] -
               (u64)(unsigned long)ipath->fspath->val;
         ipath->fspath->val[i] = rel_ptr;
     }
 
     ret = copy_to_user((void __user *)(unsigned long)ipa->fspath,
                ipath->fspath, size);
     if (ret) {
         ret = -EFAULT;
         goto out;
     }
 
 out:
     btrfs_free_path(path);
     free_ipath(ipath);
     kfree(ipa);
 
     return ret;
 }
 
 static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
                     void __user *arg, int version)
 {
     int ret = 0;
     int size;
     struct btrfs_ioctl_logical_ino_args *loi;
     struct btrfs_data_container *inodes = NULL;
     struct btrfs_path *path = NULL;
     bool ignore_offset;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     loi = memdup_user(arg, sizeof(*loi));
     if (IS_ERR(loi))
         return PTR_ERR(loi);
 
     if (version == 1) {
         ignore_offset = false;
         size = min_t(u32, loi->size, SZ_64K);
     } else {
         /* All reserved bits must be 0 for now */
         if (memchr_inv(loi->reserved, 0, sizeof(loi->reserved))) {
             ret = -EINVAL;
             goto out_loi;
         }
         /* Only accept flags we have defined so far */
         if (loi->flags & ~(BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET)) {
             ret = -EINVAL;
             goto out_loi;
         }
         ignore_offset = loi->flags & BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET;
         size = min_t(u32, loi->size, SZ_16M);
     }
 
     path = btrfs_alloc_path();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
 
     inodes = init_data_container(size);
     if (IS_ERR(inodes)) {
         ret = PTR_ERR(inodes);
         inodes = NULL;
         goto out;
     }
 
     ret = iterate_inodes_from_logical(loi->logical, fs_info, path,
                       inodes, ignore_offset);
     if (ret == -EINVAL)
         ret = -ENOENT;
     if (ret < 0)
         goto out;
 
     ret = copy_to_user((void __user *)(unsigned long)loi->inodes, inodes,
                size);
     if (ret)
         ret = -EFAULT;
 
 out:
     btrfs_free_path(path);
     kvfree(inodes);
 out_loi:
     kfree(loi);
 
     return ret;
 }
 
 void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
                    struct btrfs_ioctl_balance_args *bargs)
 {
     struct btrfs_balance_control *bctl = fs_info->balance_ctl;
 
     bargs->flags = bctl->flags;
 
     if (test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags))
         bargs->state |= BTRFS_BALANCE_STATE_RUNNING;
     if (atomic_read(&fs_info->balance_pause_req))
         bargs->state |= BTRFS_BALANCE_STATE_PAUSE_REQ;
     if (atomic_read(&fs_info->balance_cancel_req))
         bargs->state |= BTRFS_BALANCE_STATE_CANCEL_REQ;
 
     memcpy(&bargs->data, &bctl->data, sizeof(bargs->data));
     memcpy(&bargs->meta, &bctl->meta, sizeof(bargs->meta));
     memcpy(&bargs->sys, &bctl->sys, sizeof(bargs->sys));
 
     spin_lock(&fs_info->balance_lock);
     memcpy(&bargs->stat, &bctl->stat, sizeof(bargs->stat));
     spin_unlock(&fs_info->balance_lock);
 }
 
 /**
  * Try to acquire fs_info::balance_mutex as well as set BTRFS_EXLCOP_BALANCE as
  * required.
  *
  * @fs_info:       the filesystem
  * @excl_acquired: ptr to boolean value which is set to false in case balance
  *                 is being resumed
  *
  * Return 0 on success in which case both fs_info::balance is acquired as well
  * as exclusive ops are blocked. In case of failure return an error code.
  */
 static int btrfs_try_lock_balance(struct btrfs_fs_info *fs_info, bool *excl_acquired)
 {
     int ret;
 
     /*
      * Exclusive operation is locked. Three possibilities:
      *   (1) some other op is running
      *   (2) balance is running
      *   (3) balance is paused -- special case (think resume)
      */
     while (1) {
         if (btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) {
             *excl_acquired = true;
             mutex_lock(&fs_info->balance_mutex);
             return 0;
         }
 
         mutex_lock(&fs_info->balance_mutex);
         if (fs_info->balance_ctl) {
             /* This is either (2) or (3) */
             if (test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)) {
                 /* This is (2) */
                 ret = -EINPROGRESS;
                 goto out_failure;
 
             } else {
                 mutex_unlock(&fs_info->balance_mutex);
                 /*
                  * Lock released to allow other waiters to
                  * continue, we'll reexamine the status again.
                  */
                 mutex_lock(&fs_info->balance_mutex);
 
                 if (fs_info->balance_ctl &&
                     !test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)) {
                     /* This is (3) */
                     *excl_acquired = false;
                     return 0;
                 }
             }
         } else {
             /* This is (1) */
             ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
             goto out_failure;
         }
 
         mutex_unlock(&fs_info->balance_mutex);
     }
 
 out_failure:
     mutex_unlock(&fs_info->balance_mutex);
     *excl_acquired = false;
     return ret;
 }
 
 static long btrfs_ioctl_balance(struct file *file, void __user *arg)
 {
     struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_ioctl_balance_args *bargs;
     struct btrfs_balance_control *bctl;
     bool need_unlock = true;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     bargs = memdup_user(arg, sizeof(*bargs));
     if (IS_ERR(bargs)) {
         ret = PTR_ERR(bargs);
         bargs = NULL;
         goto out;
     }
 
     ret = btrfs_try_lock_balance(fs_info, &need_unlock);
     if (ret)
         goto out;
 
     lockdep_assert_held(&fs_info->balance_mutex);
 
     if (bargs->flags & BTRFS_BALANCE_RESUME) {
         if (!fs_info->balance_ctl) {
             ret = -ENOTCONN;
             goto out_unlock;
         }
 
         bctl = fs_info->balance_ctl;
         spin_lock(&fs_info->balance_lock);
         bctl->flags |= BTRFS_BALANCE_RESUME;
         spin_unlock(&fs_info->balance_lock);
         btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE);
 
         goto do_balance;
     }
 
     if (bargs->flags & ~(BTRFS_BALANCE_ARGS_MASK | BTRFS_BALANCE_TYPE_MASK)) {
         ret = -EINVAL;
         goto out_unlock;
     }
 
     if (fs_info->balance_ctl) {
         ret = -EINPROGRESS;
         goto out_unlock;
     }
 
     bctl = kzalloc(sizeof(*bctl), GFP_KERNEL);
     if (!bctl) {
         ret = -ENOMEM;
         goto out_unlock;
     }
 
     memcpy(&bctl->data, &bargs->data, sizeof(bctl->data));
     memcpy(&bctl->meta, &bargs->meta, sizeof(bctl->meta));
     memcpy(&bctl->sys, &bargs->sys, sizeof(bctl->sys));
 
     bctl->flags = bargs->flags;
 do_balance:
     /*
      * Ownership of bctl and exclusive operation goes to btrfs_balance.
      * bctl is freed in reset_balance_state, or, if restriper was paused
      * all the way until unmount, in free_fs_info.  The flag should be
      * cleared after reset_balance_state.
      */
     need_unlock = false;
 
     ret = btrfs_balance(fs_info, bctl, bargs);
     bctl = NULL;
 
     if (ret == 0 || ret == -ECANCELED) {
         if (copy_to_user(arg, bargs, sizeof(*bargs)))
             ret = -EFAULT;
     }
 
     kfree(bctl);
 out_unlock:
     mutex_unlock(&fs_info->balance_mutex);
     if (need_unlock)
         btrfs_exclop_finish(fs_info);
 out:
     mnt_drop_write_file(file);
     kfree(bargs);
     return ret;
 }
 
 static long btrfs_ioctl_balance_ctl(struct btrfs_fs_info *fs_info, int cmd)
 {
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     switch (cmd) {
     case BTRFS_BALANCE_CTL_PAUSE:
         return btrfs_pause_balance(fs_info);
     case BTRFS_BALANCE_CTL_CANCEL:
         return btrfs_cancel_balance(fs_info);
     }
 
     return -EINVAL;
 }
 
 static long btrfs_ioctl_balance_progress(struct btrfs_fs_info *fs_info,
                      void __user *arg)
 {
     struct btrfs_ioctl_balance_args *bargs;
     int ret = 0;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     mutex_lock(&fs_info->balance_mutex);
     if (!fs_info->balance_ctl) {
         ret = -ENOTCONN;
         goto out;
     }
 
     bargs = kzalloc(sizeof(*bargs), GFP_KERNEL);
     if (!bargs) {
         ret = -ENOMEM;
         goto out;
     }
 
     btrfs_update_ioctl_balance_args(fs_info, bargs);
 
     if (copy_to_user(arg, bargs, sizeof(*bargs)))
         ret = -EFAULT;
 
     kfree(bargs);
 out:
     mutex_unlock(&fs_info->balance_mutex);
     return ret;
 }
 
 static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_ioctl_quota_ctl_args *sa;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     sa = memdup_user(arg, sizeof(*sa));
     if (IS_ERR(sa)) {
         ret = PTR_ERR(sa);
         goto drop_write;
     }
 
     down_write(&fs_info->subvol_sem);
 
     switch (sa->cmd) {
     case BTRFS_QUOTA_CTL_ENABLE:
         ret = btrfs_quota_enable(fs_info);
         break;
     case BTRFS_QUOTA_CTL_DISABLE:
         ret = btrfs_quota_disable(fs_info);
         break;
     default:
         ret = -EINVAL;
         break;
     }
 
     kfree(sa);
     up_write(&fs_info->subvol_sem);
 drop_write:
     mnt_drop_write_file(file);
     return ret;
 }
 
 static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_ioctl_qgroup_assign_args *sa;
     struct btrfs_trans_handle *trans;
     int ret;
     int err;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     sa = memdup_user(arg, sizeof(*sa));
     if (IS_ERR(sa)) {
         ret = PTR_ERR(sa);
         goto drop_write;
     }
 
     trans = btrfs_join_transaction(root);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out;
     }
 
     if (sa->assign) {
         ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst);
     } else {
         ret = btrfs_del_qgroup_relation(trans, sa->src, sa->dst);
     }
 
     /* update qgroup status and info */
     err = btrfs_run_qgroups(trans);
     if (err < 0)
         btrfs_handle_fs_error(fs_info, err,
                       "failed to update qgroup status and info");
     err = btrfs_end_transaction(trans);
     if (err && !ret)
         ret = err;
 
 out:
     kfree(sa);
 drop_write:
     mnt_drop_write_file(file);
     return ret;
 }
 
 static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_ioctl_qgroup_create_args *sa;
     struct btrfs_trans_handle *trans;
     int ret;
     int err;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     sa = memdup_user(arg, sizeof(*sa));
     if (IS_ERR(sa)) {
         ret = PTR_ERR(sa);
         goto drop_write;
     }
 
     if (!sa->qgroupid) {
         ret = -EINVAL;
         goto out;
     }
 
     trans = btrfs_join_transaction(root);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out;
     }
 
     if (sa->create) {
         ret = btrfs_create_qgroup(trans, sa->qgroupid);
     } else {
         ret = btrfs_remove_qgroup(trans, sa->qgroupid);
     }
 
     err = btrfs_end_transaction(trans);
     if (err && !ret)
         ret = err;
 
 out:
     kfree(sa);
 drop_write:
     mnt_drop_write_file(file);
     return ret;
 }
 
 static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_ioctl_qgroup_limit_args *sa;
     struct btrfs_trans_handle *trans;
     int ret;
     int err;
     u64 qgroupid;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     sa = memdup_user(arg, sizeof(*sa));
     if (IS_ERR(sa)) {
         ret = PTR_ERR(sa);
         goto drop_write;
     }
 
     trans = btrfs_join_transaction(root);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out;
     }
 
     qgroupid = sa->qgroupid;
     if (!qgroupid) {
         /* take the current subvol as qgroup */
         qgroupid = root->root_key.objectid;
     }
 
     ret = btrfs_limit_qgroup(trans, qgroupid, &sa->lim);
 
     err = btrfs_end_transaction(trans);
     if (err && !ret)
         ret = err;
 
 out:
     kfree(sa);
 drop_write:
     mnt_drop_write_file(file);
     return ret;
 }
 
 static long btrfs_ioctl_quota_rescan(struct file *file, void __user *arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_ioctl_quota_rescan_args *qsa;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     qsa = memdup_user(arg, sizeof(*qsa));
     if (IS_ERR(qsa)) {
         ret = PTR_ERR(qsa);
         goto drop_write;
     }
 
     if (qsa->flags) {
         ret = -EINVAL;
         goto out;
     }
 
     ret = btrfs_qgroup_rescan(fs_info);
 
 out:
     kfree(qsa);
 drop_write:
     mnt_drop_write_file(file);
     return ret;
 }
 
 static long btrfs_ioctl_quota_rescan_status(struct btrfs_fs_info *fs_info,
                         void __user *arg)
 {
     struct btrfs_ioctl_quota_rescan_args qsa = {0};
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
         qsa.flags = 1;
         qsa.progress = fs_info->qgroup_rescan_progress.objectid;
     }
 
     if (copy_to_user(arg, &qsa, sizeof(qsa)))
         return -EFAULT;
 
     return 0;
 }
 
 static long btrfs_ioctl_quota_rescan_wait(struct btrfs_fs_info *fs_info,
                         void __user *arg)
 {
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     return btrfs_qgroup_wait_for_completion(fs_info, true);
 }
 
 static long _btrfs_ioctl_set_received_subvol(struct file *file,
                         struct user_namespace *mnt_userns,
                         struct btrfs_ioctl_received_subvol_args *sa)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_root_item *root_item = &root->root_item;
     struct btrfs_trans_handle *trans;
     struct timespec64 ct = current_time(inode);
     int ret = 0;
     int received_uuid_changed;
 
     if (!inode_owner_or_capable(mnt_userns, inode))
         return -EPERM;
 
     ret = mnt_want_write_file(file);
     if (ret < 0)
         return ret;
 
     down_write(&fs_info->subvol_sem);
 
     if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
         ret = -EINVAL;
         goto out;
     }
 
     if (btrfs_root_readonly(root)) {
         ret = -EROFS;
         goto out;
     }
 
     /*
      * 1 - root item
      * 2 - uuid items (received uuid + subvol uuid)
      */
     trans = btrfs_start_transaction(root, 3);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         trans = NULL;
         goto out;
     }
 
     sa->rtransid = trans->transid;
     sa->rtime.sec = ct.tv_sec;
     sa->rtime.nsec = ct.tv_nsec;
 
     received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
                        BTRFS_UUID_SIZE);
     if (received_uuid_changed &&
         !btrfs_is_empty_uuid(root_item->received_uuid)) {
         ret = btrfs_uuid_tree_remove(trans, root_item->received_uuid,
                       BTRFS_UUID_KEY_RECEIVED_SUBVOL,
                       root->root_key.objectid);
         if (ret && ret != -ENOENT) {
                 btrfs_abort_transaction(trans, ret);
                 btrfs_end_transaction(trans);
                 goto out;
         }
     }
     memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
     btrfs_set_root_stransid(root_item, sa->stransid);
     btrfs_set_root_rtransid(root_item, sa->rtransid);
     btrfs_set_stack_timespec_sec(&root_item->stime, sa->stime.sec);
     btrfs_set_stack_timespec_nsec(&root_item->stime, sa->stime.nsec);
     btrfs_set_stack_timespec_sec(&root_item->rtime, sa->rtime.sec);
     btrfs_set_stack_timespec_nsec(&root_item->rtime, sa->rtime.nsec);
 
     ret = btrfs_update_root(trans, fs_info->tree_root,
                 &root->root_key, &root->root_item);
     if (ret < 0) {
         btrfs_end_transaction(trans);
         goto out;
     }
     if (received_uuid_changed && !btrfs_is_empty_uuid(sa->uuid)) {
         ret = btrfs_uuid_tree_add(trans, sa->uuid,
                       BTRFS_UUID_KEY_RECEIVED_SUBVOL,
                       root->root_key.objectid);
         if (ret < 0 && ret != -EEXIST) {
             btrfs_abort_transaction(trans, ret);
             btrfs_end_transaction(trans);
             goto out;
         }
     }
     ret = btrfs_commit_transaction(trans);
 out:
     up_write(&fs_info->subvol_sem);
     mnt_drop_write_file(file);
     return ret;
 }
 
 #ifdef CONFIG_64BIT
 static long btrfs_ioctl_set_received_subvol_32(struct file *file,
                         void __user *arg)
 {
     struct btrfs_ioctl_received_subvol_args_32 *args32 = NULL;
     struct btrfs_ioctl_received_subvol_args *args64 = NULL;
     int ret = 0;
 
     args32 = memdup_user(arg, sizeof(*args32));
     if (IS_ERR(args32))
         return PTR_ERR(args32);
 
     args64 = kmalloc(sizeof(*args64), GFP_KERNEL);
     if (!args64) {
         ret = -ENOMEM;
         goto out;
     }
 
     memcpy(args64->uuid, args32->uuid, BTRFS_UUID_SIZE);
     args64->stransid = args32->stransid;
     args64->rtransid = args32->rtransid;
     args64->stime.sec = args32->stime.sec;
     args64->stime.nsec = args32->stime.nsec;
     args64->rtime.sec = args32->rtime.sec;
     args64->rtime.nsec = args32->rtime.nsec;
     args64->flags = args32->flags;
 
     ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_user_ns(file), args64);
     if (ret)
         goto out;
 
     memcpy(args32->uuid, args64->uuid, BTRFS_UUID_SIZE);
     args32->stransid = args64->stransid;
     args32->rtransid = args64->rtransid;
     args32->stime.sec = args64->stime.sec;
     args32->stime.nsec = args64->stime.nsec;
     args32->rtime.sec = args64->rtime.sec;
     args32->rtime.nsec = args64->rtime.nsec;
     args32->flags = args64->flags;
 
     ret = copy_to_user(arg, args32, sizeof(*args32));
     if (ret)
         ret = -EFAULT;
 
 out:
     kfree(args32);
     kfree(args64);
     return ret;
 }
 #endif
 
 static long btrfs_ioctl_set_received_subvol(struct file *file,
                         void __user *arg)
 {
     struct btrfs_ioctl_received_subvol_args *sa = NULL;
     int ret = 0;
 
     sa = memdup_user(arg, sizeof(*sa));
     if (IS_ERR(sa))
         return PTR_ERR(sa);
 
     ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_user_ns(file), sa);
 
     if (ret)
         goto out;
 
     ret = copy_to_user(arg, sa, sizeof(*sa));
     if (ret)
         ret = -EFAULT;
 
 out:
     kfree(sa);
     return ret;
 }
 
 static int btrfs_ioctl_get_fslabel(struct btrfs_fs_info *fs_info,
                     void __user *arg)
 {
     size_t len;
     int ret;
     char label[BTRFS_LABEL_SIZE];
 
     spin_lock(&fs_info->super_lock);
     memcpy(label, fs_info->super_copy->label, BTRFS_LABEL_SIZE);
     spin_unlock(&fs_info->super_lock);
 
     len = strnlen(label, BTRFS_LABEL_SIZE);
 
     if (len == BTRFS_LABEL_SIZE) {
         btrfs_warn(fs_info,
                "label is too long, return the first %zu bytes",
                --len);
     }
 
     ret = copy_to_user(arg, label, len);
 
     return ret ? -EFAULT : 0;
 }
 
 static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_super_block *super_block = fs_info->super_copy;
     struct btrfs_trans_handle *trans;
     char label[BTRFS_LABEL_SIZE];
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     if (copy_from_user(label, arg, sizeof(label)))
         return -EFAULT;
 
     if (strnlen(label, BTRFS_LABEL_SIZE) == BTRFS_LABEL_SIZE) {
         btrfs_err(fs_info,
               "unable to set label with more than %d bytes",
               BTRFS_LABEL_SIZE - 1);
         return -EINVAL;
     }
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     trans = btrfs_start_transaction(root, 0);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out_unlock;
     }
 
     spin_lock(&fs_info->super_lock);
     strcpy(super_block->label, label);
     spin_unlock(&fs_info->super_lock);
     ret = btrfs_commit_transaction(trans);
 
 out_unlock:
     mnt_drop_write_file(file);
     return ret;
 }
 
 #define INIT_FEATURE_FLAGS(suffix) \
     { .compat_flags = BTRFS_FEATURE_COMPAT_##suffix, \
       .compat_ro_flags = BTRFS_FEATURE_COMPAT_RO_##suffix, \
       .incompat_flags = BTRFS_FEATURE_INCOMPAT_##suffix }
 
 int btrfs_ioctl_get_supported_features(void __user *arg)
 {
     static const struct btrfs_ioctl_feature_flags features[3] = {
         INIT_FEATURE_FLAGS(SUPP),
         INIT_FEATURE_FLAGS(SAFE_SET),
         INIT_FEATURE_FLAGS(SAFE_CLEAR)
     };
 
     if (copy_to_user(arg, &features, sizeof(features)))
         return -EFAULT;
 
     return 0;
 }
 
 static int btrfs_ioctl_get_features(struct btrfs_fs_info *fs_info,
                     void __user *arg)
 {
     struct btrfs_super_block *super_block = fs_info->super_copy;
     struct btrfs_ioctl_feature_flags features;
 
     features.compat_flags = btrfs_super_compat_flags(super_block);
     features.compat_ro_flags = btrfs_super_compat_ro_flags(super_block);
     features.incompat_flags = btrfs_super_incompat_flags(super_block);
 
     if (copy_to_user(arg, &features, sizeof(features)))
         return -EFAULT;
 
     return 0;
 }
 
 static int check_feature_bits(struct btrfs_fs_info *fs_info,
                   enum btrfs_feature_set set,
                   u64 change_mask, u64 flags, u64 supported_flags,
                   u64 safe_set, u64 safe_clear)
 {
     const char *type = btrfs_feature_set_name(set);
     char *names;
     u64 disallowed, unsupported;
     u64 set_mask = flags & change_mask;
     u64 clear_mask = ~flags & change_mask;
 
     unsupported = set_mask & ~supported_flags;
     if (unsupported) {
         names = btrfs_printable_features(set, unsupported);
         if (names) {
             btrfs_warn(fs_info,
                    "this kernel does not support the %s feature bit%s",
                    names, strchr(names, ',') ? "s" : "");
             kfree(names);
         } else
             btrfs_warn(fs_info,
                    "this kernel does not support %s bits 0x%llx",
                    type, unsupported);
         return -EOPNOTSUPP;
     }
 
     disallowed = set_mask & ~safe_set;
     if (disallowed) {
         names = btrfs_printable_features(set, disallowed);
         if (names) {
             btrfs_warn(fs_info,
                    "can't set the %s feature bit%s while mounted",
                    names, strchr(names, ',') ? "s" : "");
             kfree(names);
         } else
             btrfs_warn(fs_info,
                    "can't set %s bits 0x%llx while mounted",
                    type, disallowed);
         return -EPERM;
     }
 
     disallowed = clear_mask & ~safe_clear;
     if (disallowed) {
         names = btrfs_printable_features(set, disallowed);
         if (names) {
             btrfs_warn(fs_info,
                    "can't clear the %s feature bit%s while mounted",
                    names, strchr(names, ',') ? "s" : "");
             kfree(names);
         } else
             btrfs_warn(fs_info,
                    "can't clear %s bits 0x%llx while mounted",
                    type, disallowed);
         return -EPERM;
     }
 
     return 0;
 }
 
 #define check_feature(fs_info, change_mask, flags, mask_base)   \
 check_feature_bits(fs_info, FEAT_##mask_base, change_mask, flags,   \
            BTRFS_FEATURE_ ## mask_base ## _SUPP,    \
            BTRFS_FEATURE_ ## mask_base ## _SAFE_SET,    \
            BTRFS_FEATURE_ ## mask_base ## _SAFE_CLEAR)
 
 static int btrfs_ioctl_set_features(struct file *file, void __user *arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_super_block *super_block = fs_info->super_copy;
     struct btrfs_ioctl_feature_flags flags[2];
     struct btrfs_trans_handle *trans;
     u64 newflags;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     if (copy_from_user(flags, arg, sizeof(flags)))
         return -EFAULT;
 
     /* Nothing to do */
     if (!flags[0].compat_flags && !flags[0].compat_ro_flags &&
         !flags[0].incompat_flags)
         return 0;
 
     ret = check_feature(fs_info, flags[0].compat_flags,
                 flags[1].compat_flags, COMPAT);
     if (ret)
         return ret;
 
     ret = check_feature(fs_info, flags[0].compat_ro_flags,
                 flags[1].compat_ro_flags, COMPAT_RO);
     if (ret)
         return ret;
 
     ret = check_feature(fs_info, flags[0].incompat_flags,
                 flags[1].incompat_flags, INCOMPAT);
     if (ret)
         return ret;
 
     ret = mnt_want_write_file(file);
     if (ret)
         return ret;
 
     trans = btrfs_start_transaction(root, 0);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out_drop_write;
     }
 
     spin_lock(&fs_info->super_lock);
     newflags = btrfs_super_compat_flags(super_block);
     newflags |= flags[0].compat_flags & flags[1].compat_flags;
     newflags &= ~(flags[0].compat_flags & ~flags[1].compat_flags);
     btrfs_set_super_compat_flags(super_block, newflags);
 
     newflags = btrfs_super_compat_ro_flags(super_block);
     newflags |= flags[0].compat_ro_flags & flags[1].compat_ro_flags;
     newflags &= ~(flags[0].compat_ro_flags & ~flags[1].compat_ro_flags);
     btrfs_set_super_compat_ro_flags(super_block, newflags);
 
     newflags = btrfs_super_incompat_flags(super_block);
     newflags |= flags[0].incompat_flags & flags[1].incompat_flags;
     newflags &= ~(flags[0].incompat_flags & ~flags[1].incompat_flags);
     btrfs_set_super_incompat_flags(super_block, newflags);
     spin_unlock(&fs_info->super_lock);
 
     ret = btrfs_commit_transaction(trans);
 out_drop_write:
     mnt_drop_write_file(file);
 
     return ret;
 }
 
 static int _btrfs_ioctl_send(struct inode *inode, void __user *argp, bool compat)
 {
     struct btrfs_ioctl_send_args *arg;
     int ret;
 
     if (compat) {
 #if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
         struct btrfs_ioctl_send_args_32 args32;
 
         ret = copy_from_user(&args32, argp, sizeof(args32));
         if (ret)
             return -EFAULT;
         arg = kzalloc(sizeof(*arg), GFP_KERNEL);
         if (!arg)
             return -ENOMEM;
         arg->send_fd = args32.send_fd;
         arg->clone_sources_count = args32.clone_sources_count;
         arg->clone_sources = compat_ptr(args32.clone_sources);
         arg->parent_root = args32.parent_root;
         arg->flags = args32.flags;
         memcpy(arg->reserved, args32.reserved,
                sizeof(args32.reserved));
 #else
         return -ENOTTY;
 #endif
     } else {
         arg = memdup_user(argp, sizeof(*arg));
         if (IS_ERR(arg))
             return PTR_ERR(arg);
     }
     ret = btrfs_ioctl_send(inode, arg);
     kfree(arg);
     return ret;
 }
 
 static int btrfs_ioctl_encoded_read(struct file *file, void __user *argp,
                     bool compat)
 {
     struct btrfs_ioctl_encoded_io_args args = { 0 };
     size_t copy_end_kernel = offsetofend(struct btrfs_ioctl_encoded_io_args,
                          flags);
     size_t copy_end;
     struct iovec iovstack[UIO_FASTIOV];
     struct iovec *iov = iovstack;
     struct iov_iter iter;
     loff_t pos;
     struct kiocb kiocb;
     ssize_t ret;
 
     if (!capable(CAP_SYS_ADMIN)) {
         ret = -EPERM;
         goto out_acct;
     }
 
     if (compat) {
 #if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
         struct btrfs_ioctl_encoded_io_args_32 args32;
 
         copy_end = offsetofend(struct btrfs_ioctl_encoded_io_args_32,
                        flags);
         if (copy_from_user(&args32, argp, copy_end)) {
             ret = -EFAULT;
             goto out_acct;
         }
         args.iov = compat_ptr(args32.iov);
         args.iovcnt = args32.iovcnt;
         args.offset = args32.offset;
         args.flags = args32.flags;
 #else
         return -ENOTTY;
 #endif
     } else {
         copy_end = copy_end_kernel;
         if (copy_from_user(&args, argp, copy_end)) {
             ret = -EFAULT;
             goto out_acct;
         }
     }
     if (args.flags != 0) {
         ret = -EINVAL;
         goto out_acct;
     }
 
     ret = import_iovec(READ, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
                &iov, &iter);
     if (ret < 0)
         goto out_acct;
 
     if (iov_iter_count(&iter) == 0) {
         ret = 0;
         goto out_iov;
     }
     pos = args.offset;
     ret = rw_verify_area(READ, file, &pos, args.len);
     if (ret < 0)
         goto out_iov;
 
     init_sync_kiocb(&kiocb, file);
     kiocb.ki_pos = pos;
 
     ret = btrfs_encoded_read(&kiocb, &iter, &args);
     if (ret >= 0) {
         fsnotify_access(file);
         if (copy_to_user(argp + copy_end,
                  (char *)&args + copy_end_kernel,
                  sizeof(args) - copy_end_kernel))
             ret = -EFAULT;
     }
 
 out_iov:
     kfree(iov);
 out_acct:
     if (ret > 0)
         add_rchar(current, ret);
     inc_syscr(current);
     return ret;
 }
 
 static int btrfs_ioctl_encoded_write(struct file *file, void __user *argp, bool compat)
 {
     struct btrfs_ioctl_encoded_io_args args;
     struct iovec iovstack[UIO_FASTIOV];
     struct iovec *iov = iovstack;
     struct iov_iter iter;
     loff_t pos;
     struct kiocb kiocb;
     ssize_t ret;
 
     if (!capable(CAP_SYS_ADMIN)) {
         ret = -EPERM;
         goto out_acct;
     }
 
     if (!(file->f_mode & FMODE_WRITE)) {
         ret = -EBADF;
         goto out_acct;
     }
 
     if (compat) {
 #if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
         struct btrfs_ioctl_encoded_io_args_32 args32;
 
         if (copy_from_user(&args32, argp, sizeof(args32))) {
             ret = -EFAULT;
             goto out_acct;
         }
         args.iov = compat_ptr(args32.iov);
         args.iovcnt = args32.iovcnt;
         args.offset = args32.offset;
         args.flags = args32.flags;
         args.len = args32.len;
         args.unencoded_len = args32.unencoded_len;
         args.unencoded_offset = args32.unencoded_offset;
         args.compression = args32.compression;
         args.encryption = args32.encryption;
         memcpy(args.reserved, args32.reserved, sizeof(args.reserved));
 #else
         return -ENOTTY;
 #endif
     } else {
         if (copy_from_user(&args, argp, sizeof(args))) {
             ret = -EFAULT;
             goto out_acct;
         }
     }
 
     ret = -EINVAL;
     if (args.flags != 0)
         goto out_acct;
     if (memchr_inv(args.reserved, 0, sizeof(args.reserved)))
         goto out_acct;
     if (args.compression == BTRFS_ENCODED_IO_COMPRESSION_NONE &&
         args.encryption == BTRFS_ENCODED_IO_ENCRYPTION_NONE)
         goto out_acct;
     if (args.compression >= BTRFS_ENCODED_IO_COMPRESSION_TYPES ||
         args.encryption >= BTRFS_ENCODED_IO_ENCRYPTION_TYPES)
         goto out_acct;
     if (args.unencoded_offset > args.unencoded_len)
         goto out_acct;
     if (args.len > args.unencoded_len - args.unencoded_offset)
         goto out_acct;
 
     ret = import_iovec(WRITE, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
                &iov, &iter);
     if (ret < 0)
         goto out_acct;
 
     file_start_write(file);
 
     if (iov_iter_count(&iter) == 0) {
         ret = 0;
         goto out_end_write;
     }
     pos = args.offset;
     ret = rw_verify_area(WRITE, file, &pos, args.len);
     if (ret < 0)
         goto out_end_write;
 
     init_sync_kiocb(&kiocb, file);
     ret = kiocb_set_rw_flags(&kiocb, 0);
     if (ret)
         goto out_end_write;
     kiocb.ki_pos = pos;
 
     ret = btrfs_do_write_iter(&kiocb, &iter, &args);
     if (ret > 0)
         fsnotify_modify(file);
 
 out_end_write:
     file_end_write(file);
     kfree(iov);
 out_acct:
     if (ret > 0)
         add_wchar(current, ret);
     inc_syscw(current);
     return ret;
 }
 
 long btrfs_ioctl(struct file *file, unsigned int
         cmd, unsigned long arg)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     void __user *argp = (void __user *)arg;
 
     switch (cmd) {
     case FS_IOC_GETVERSION:
         return btrfs_ioctl_getversion(inode, argp);
     case FS_IOC_GETFSLABEL:
         return btrfs_ioctl_get_fslabel(fs_info, argp);
     case FS_IOC_SETFSLABEL:
         return btrfs_ioctl_set_fslabel(file, argp);
     case FITRIM:
         return btrfs_ioctl_fitrim(fs_info, argp);
     case BTRFS_IOC_SNAP_CREATE:
         return btrfs_ioctl_snap_create(file, argp, 0);
     case BTRFS_IOC_SNAP_CREATE_V2:
         return btrfs_ioctl_snap_create_v2(file, argp, 0);
     case BTRFS_IOC_SUBVOL_CREATE:
         return btrfs_ioctl_snap_create(file, argp, 1);
     case BTRFS_IOC_SUBVOL_CREATE_V2:
         return btrfs_ioctl_snap_create_v2(file, argp, 1);
     case BTRFS_IOC_SNAP_DESTROY:
         return btrfs_ioctl_snap_destroy(file, argp, false);
     case BTRFS_IOC_SNAP_DESTROY_V2:
         return btrfs_ioctl_snap_destroy(file, argp, true);
     case BTRFS_IOC_SUBVOL_GETFLAGS:
         return btrfs_ioctl_subvol_getflags(inode, argp);
     case BTRFS_IOC_SUBVOL_SETFLAGS:
         return btrfs_ioctl_subvol_setflags(file, argp);
     case BTRFS_IOC_DEFAULT_SUBVOL:
         return btrfs_ioctl_default_subvol(file, argp);
     case BTRFS_IOC_DEFRAG:
         return btrfs_ioctl_defrag(file, NULL);
     case BTRFS_IOC_DEFRAG_RANGE:
         return btrfs_ioctl_defrag(file, argp);
     case BTRFS_IOC_RESIZE:
         return btrfs_ioctl_resize(file, argp);
     case BTRFS_IOC_ADD_DEV:
         return btrfs_ioctl_add_dev(fs_info, argp);
     case BTRFS_IOC_RM_DEV:
         return btrfs_ioctl_rm_dev(file, argp);
     case BTRFS_IOC_RM_DEV_V2:
         return btrfs_ioctl_rm_dev_v2(file, argp);
     case BTRFS_IOC_FS_INFO:
         return btrfs_ioctl_fs_info(fs_info, argp);
     case BTRFS_IOC_DEV_INFO:
         return btrfs_ioctl_dev_info(fs_info, argp);
     case BTRFS_IOC_TREE_SEARCH:
         return btrfs_ioctl_tree_search(inode, argp);
     case BTRFS_IOC_TREE_SEARCH_V2:
         return btrfs_ioctl_tree_search_v2(inode, argp);
     case BTRFS_IOC_INO_LOOKUP:
         return btrfs_ioctl_ino_lookup(root, argp);
     case BTRFS_IOC_INO_PATHS:
         return btrfs_ioctl_ino_to_path(root, argp);
     case BTRFS_IOC_LOGICAL_INO:
         return btrfs_ioctl_logical_to_ino(fs_info, argp, 1);
     case BTRFS_IOC_LOGICAL_INO_V2:
         return btrfs_ioctl_logical_to_ino(fs_info, argp, 2);
     case BTRFS_IOC_SPACE_INFO:
         return btrfs_ioctl_space_info(fs_info, argp);
     case BTRFS_IOC_SYNC: {
         int ret;
 
         ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
         if (ret)
             return ret;
         ret = btrfs_sync_fs(inode->i_sb, 1);
         /*
          * The transaction thread may want to do more work,
          * namely it pokes the cleaner kthread that will start
          * processing uncleaned subvols.
          */
         wake_up_process(fs_info->transaction_kthread);
         return ret;
     }
     case BTRFS_IOC_START_SYNC:
         return btrfs_ioctl_start_sync(root, argp);
     case BTRFS_IOC_WAIT_SYNC:
         return btrfs_ioctl_wait_sync(fs_info, argp);
     case BTRFS_IOC_SCRUB:
         return btrfs_ioctl_scrub(file, argp);
     case BTRFS_IOC_SCRUB_CANCEL:
         return btrfs_ioctl_scrub_cancel(fs_info);
     case BTRFS_IOC_SCRUB_PROGRESS:
         return btrfs_ioctl_scrub_progress(fs_info, argp);
     case BTRFS_IOC_BALANCE_V2:
         return btrfs_ioctl_balance(file, argp);
     case BTRFS_IOC_BALANCE_CTL:
         return btrfs_ioctl_balance_ctl(fs_info, arg);
     case BTRFS_IOC_BALANCE_PROGRESS:
         return btrfs_ioctl_balance_progress(fs_info, argp);
     case BTRFS_IOC_SET_RECEIVED_SUBVOL:
         return btrfs_ioctl_set_received_subvol(file, argp);
 #ifdef CONFIG_64BIT
     case BTRFS_IOC_SET_RECEIVED_SUBVOL_32:
         return btrfs_ioctl_set_received_subvol_32(file, argp);
 #endif
     case BTRFS_IOC_SEND:
         return _btrfs_ioctl_send(inode, argp, false);
 #if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
     case BTRFS_IOC_SEND_32:
         return _btrfs_ioctl_send(inode, argp, true);
 #endif
     case BTRFS_IOC_GET_DEV_STATS:
         return btrfs_ioctl_get_dev_stats(fs_info, argp);
     case BTRFS_IOC_QUOTA_CTL:
         return btrfs_ioctl_quota_ctl(file, argp);
     case BTRFS_IOC_QGROUP_ASSIGN:
         return btrfs_ioctl_qgroup_assign(file, argp);
     case BTRFS_IOC_QGROUP_CREATE:
         return btrfs_ioctl_qgroup_create(file, argp);
     case BTRFS_IOC_QGROUP_LIMIT:
         return btrfs_ioctl_qgroup_limit(file, argp);
     case BTRFS_IOC_QUOTA_RESCAN:
         return btrfs_ioctl_quota_rescan(file, argp);
     case BTRFS_IOC_QUOTA_RESCAN_STATUS:
         return btrfs_ioctl_quota_rescan_status(fs_info, argp);
     case BTRFS_IOC_QUOTA_RESCAN_WAIT:
         return btrfs_ioctl_quota_rescan_wait(fs_info, argp);
     case BTRFS_IOC_DEV_REPLACE:
         return btrfs_ioctl_dev_replace(fs_info, argp);
     case BTRFS_IOC_GET_SUPPORTED_FEATURES:
         return btrfs_ioctl_get_supported_features(argp);
     case BTRFS_IOC_GET_FEATURES:
         return btrfs_ioctl_get_features(fs_info, argp);
     case BTRFS_IOC_SET_FEATURES:
         return btrfs_ioctl_set_features(file, argp);
     case BTRFS_IOC_GET_SUBVOL_INFO:
         return btrfs_ioctl_get_subvol_info(inode, argp);
     case BTRFS_IOC_GET_SUBVOL_ROOTREF:
         return btrfs_ioctl_get_subvol_rootref(root, argp);
     case BTRFS_IOC_INO_LOOKUP_USER:
         return btrfs_ioctl_ino_lookup_user(file, argp);
     case FS_IOC_ENABLE_VERITY:
         return fsverity_ioctl_enable(file, (const void __user *)argp);
     case FS_IOC_MEASURE_VERITY:
         return fsverity_ioctl_measure(file, argp);
     case BTRFS_IOC_ENCODED_READ:
         return btrfs_ioctl_encoded_read(file, argp, false);
     case BTRFS_IOC_ENCODED_WRITE:
         return btrfs_ioctl_encoded_write(file, argp, false);
 #if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
     case BTRFS_IOC_ENCODED_READ_32:
         return btrfs_ioctl_encoded_read(file, argp, true);
     case BTRFS_IOC_ENCODED_WRITE_32:
         return btrfs_ioctl_encoded_write(file, argp, true);
 #endif
     }
 
     return -ENOTTY;
 }
 
 #ifdef CONFIG_COMPAT
 long btrfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
     /*
      * These all access 32-bit values anyway so no further
      * handling is necessary.
      */
     switch (cmd) {
     case FS_IOC32_GETVERSION:
         cmd = FS_IOC_GETVERSION;
         break;
     }
 
     return btrfs_ioctl(file, cmd, (unsigned long) compat_ptr(arg));
 }
 #endif