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	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) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
  * Written by Alex Tomas <alex@clusterfs.com>
  *
  * Architecture independence:
  *   Copyright (c) 2005, Bull S.A.
  *   Written by Pierre Peiffer <pierre.peiffer@bull.net>
  */
 
 /*
  * Extents support for EXT4
  *
  * TODO:
  *   - ext4*_error() should be used in some situations
  *   - analyze all BUG()/BUG_ON(), use -EIO where appropriate
  *   - smart tree reduction
  */
 
 #include <linux/fs.h>
 #include <linux/time.h>
 #include <linux/jbd2.h>
 #include <linux/highuid.h>
 #include <linux/pagemap.h>
 #include <linux/quotaops.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/fiemap.h>
 #include <linux/iomap.h>
 #include <linux/sched/mm.h>
 #include "ext4_jbd2.h"
 #include "ext4_extents.h"
 #include "xattr.h"
 
 #include <trace/events/ext4.h>
 
 /*
  * used by extent splitting.
  */
 #define EXT4_EXT_MAY_ZEROOUT    0x1  /* safe to zeroout if split fails \
                     due to ENOSPC */
 #define EXT4_EXT_MARK_UNWRIT1   0x2  /* mark first half unwritten */
 #define EXT4_EXT_MARK_UNWRIT2   0x4  /* mark second half unwritten */
 
 #define EXT4_EXT_DATA_VALID1    0x8  /* first half contains valid data */
 #define EXT4_EXT_DATA_VALID2    0x10 /* second half contains valid data */
 
 static __le32 ext4_extent_block_csum(struct inode *inode,
                      struct ext4_extent_header *eh)
 {
     struct ext4_inode_info *ei = EXT4_I(inode);
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     __u32 csum;
 
     csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)eh,
                EXT4_EXTENT_TAIL_OFFSET(eh));
     return cpu_to_le32(csum);
 }
 
 static int ext4_extent_block_csum_verify(struct inode *inode,
                      struct ext4_extent_header *eh)
 {
     struct ext4_extent_tail *et;
 
     if (!ext4_has_metadata_csum(inode->i_sb))
         return 1;
 
     et = find_ext4_extent_tail(eh);
     if (et->et_checksum != ext4_extent_block_csum(inode, eh))
         return 0;
     return 1;
 }
 
 static void ext4_extent_block_csum_set(struct inode *inode,
                        struct ext4_extent_header *eh)
 {
     struct ext4_extent_tail *et;
 
     if (!ext4_has_metadata_csum(inode->i_sb))
         return;
 
     et = find_ext4_extent_tail(eh);
     et->et_checksum = ext4_extent_block_csum(inode, eh);
 }
 
 static int ext4_split_extent_at(handle_t *handle,
                  struct inode *inode,
                  struct ext4_ext_path **ppath,
                  ext4_lblk_t split,
                  int split_flag,
                  int flags);
 
 static int ext4_ext_trunc_restart_fn(struct inode *inode, int *dropped)
 {
     /*
      * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
      * moment, get_block can be called only for blocks inside i_size since
      * page cache has been already dropped and writes are blocked by
      * i_rwsem. So we can safely drop the i_data_sem here.
      */
     BUG_ON(EXT4_JOURNAL(inode) == NULL);
     ext4_discard_preallocations(inode, 0);
     up_write(&EXT4_I(inode)->i_data_sem);
     *dropped = 1;
     return 0;
 }
 
 /*
  * Make sure 'handle' has at least 'check_cred' credits. If not, restart
  * transaction with 'restart_cred' credits. The function drops i_data_sem
  * when restarting transaction and gets it after transaction is restarted.
  *
  * The function returns 0 on success, 1 if transaction had to be restarted,
  * and < 0 in case of fatal error.
  */
 int ext4_datasem_ensure_credits(handle_t *handle, struct inode *inode,
                 int check_cred, int restart_cred,
                 int revoke_cred)
 {
     int ret;
     int dropped = 0;
 
     ret = ext4_journal_ensure_credits_fn(handle, check_cred, restart_cred,
         revoke_cred, ext4_ext_trunc_restart_fn(inode, &dropped));
     if (dropped)
         down_write(&EXT4_I(inode)->i_data_sem);
     return ret;
 }
 
 /*
  * could return:
  *  - EROFS
  *  - ENOMEM
  */
 static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
                 struct ext4_ext_path *path)
 {
     int err = 0;
 
     if (path->p_bh) {
         /* path points to block */
         BUFFER_TRACE(path->p_bh, "get_write_access");
         err = ext4_journal_get_write_access(handle, inode->i_sb,
                             path->p_bh, EXT4_JTR_NONE);
         /*
          * The extent buffer's verified bit will be set again in
          * __ext4_ext_dirty(). We could leave an inconsistent
          * buffer if the extents updating procudure break off du
          * to some error happens, force to check it again.
          */
         if (!err)
             clear_buffer_verified(path->p_bh);
     }
     /* path points to leaf/index in inode body */
     /* we use in-core data, no need to protect them */
     return err;
 }
 
 /*
  * could return:
  *  - EROFS
  *  - ENOMEM
  *  - EIO
  */
 static int __ext4_ext_dirty(const char *where, unsigned int line,
                 handle_t *handle, struct inode *inode,
                 struct ext4_ext_path *path)
 {
     int err;
 
     WARN_ON(!rwsem_is_locked(&EXT4_I(inode)->i_data_sem));
     if (path->p_bh) {
         ext4_extent_block_csum_set(inode, ext_block_hdr(path->p_bh));
         /* path points to block */
         err = __ext4_handle_dirty_metadata(where, line, handle,
                            inode, path->p_bh);
         /* Extents updating done, re-set verified flag */
         if (!err)
             set_buffer_verified(path->p_bh);
     } else {
         /* path points to leaf/index in inode body */
         err = ext4_mark_inode_dirty(handle, inode);
     }
     return err;
 }
 
 #define ext4_ext_dirty(handle, inode, path) \
         __ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path))
 
 static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
                   struct ext4_ext_path *path,
                   ext4_lblk_t block)
 {
     if (path) {
         int depth = path->p_depth;
         struct ext4_extent *ex;
 
         /*
          * Try to predict block placement assuming that we are
          * filling in a file which will eventually be
          * non-sparse --- i.e., in the case of libbfd writing
          * an ELF object sections out-of-order but in a way
          * the eventually results in a contiguous object or
          * executable file, or some database extending a table
          * space file.  However, this is actually somewhat
          * non-ideal if we are writing a sparse file such as
          * qemu or KVM writing a raw image file that is going
          * to stay fairly sparse, since it will end up
          * fragmenting the file system's free space.  Maybe we
          * should have some hueristics or some way to allow
          * userspace to pass a hint to file system,
          * especially if the latter case turns out to be
          * common.
          */
         ex = path[depth].p_ext;
         if (ex) {
             ext4_fsblk_t ext_pblk = ext4_ext_pblock(ex);
             ext4_lblk_t ext_block = le32_to_cpu(ex->ee_block);
 
             if (block > ext_block)
                 return ext_pblk + (block - ext_block);
             else
                 return ext_pblk - (ext_block - block);
         }
 
         /* it looks like index is empty;
          * try to find starting block from index itself */
         if (path[depth].p_bh)
             return path[depth].p_bh->b_blocknr;
     }
 
     /* OK. use inode's group */
     return ext4_inode_to_goal_block(inode);
 }
 
 /*
  * Allocation for a meta data block
  */
 static ext4_fsblk_t
 ext4_ext_new_meta_block(handle_t *handle, struct inode *inode,
             struct ext4_ext_path *path,
             struct ext4_extent *ex, int *err, unsigned int flags)
 {
     ext4_fsblk_t goal, newblock;
 
     goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
     newblock = ext4_new_meta_blocks(handle, inode, goal, flags,
                     NULL, err);
     return newblock;
 }
 
 static inline int ext4_ext_space_block(struct inode *inode, int check)
 {
     int size;
 
     size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
             / sizeof(struct ext4_extent);
 #ifdef AGGRESSIVE_TEST
     if (!check && size > 6)
         size = 6;
 #endif
     return size;
 }
 
 static inline int ext4_ext_space_block_idx(struct inode *inode, int check)
 {
     int size;
 
     size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
             / sizeof(struct ext4_extent_idx);
 #ifdef AGGRESSIVE_TEST
     if (!check && size > 5)
         size = 5;
 #endif
     return size;
 }
 
 static inline int ext4_ext_space_root(struct inode *inode, int check)
 {
     int size;
 
     size = sizeof(EXT4_I(inode)->i_data);
     size -= sizeof(struct ext4_extent_header);
     size /= sizeof(struct ext4_extent);
 #ifdef AGGRESSIVE_TEST
     if (!check && size > 3)
         size = 3;
 #endif
     return size;
 }
 
 static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
 {
     int size;
 
     size = sizeof(EXT4_I(inode)->i_data);
     size -= sizeof(struct ext4_extent_header);
     size /= sizeof(struct ext4_extent_idx);
 #ifdef AGGRESSIVE_TEST
     if (!check && size > 4)
         size = 4;
 #endif
     return size;
 }
 
 static inline int
 ext4_force_split_extent_at(handle_t *handle, struct inode *inode,
                struct ext4_ext_path **ppath, ext4_lblk_t lblk,
                int nofail)
 {
     struct ext4_ext_path *path = *ppath;
     int unwritten = ext4_ext_is_unwritten(path[path->p_depth].p_ext);
     int flags = EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO;
 
     if (nofail)
         flags |= EXT4_GET_BLOCKS_METADATA_NOFAIL | EXT4_EX_NOFAIL;
 
     return ext4_split_extent_at(handle, inode, ppath, lblk, unwritten ?
             EXT4_EXT_MARK_UNWRIT1|EXT4_EXT_MARK_UNWRIT2 : 0,
             flags);
 }
 
 static int
 ext4_ext_max_entries(struct inode *inode, int depth)
 {
     int max;
 
     if (depth == ext_depth(inode)) {
         if (depth == 0)
             max = ext4_ext_space_root(inode, 1);
         else
             max = ext4_ext_space_root_idx(inode, 1);
     } else {
         if (depth == 0)
             max = ext4_ext_space_block(inode, 1);
         else
             max = ext4_ext_space_block_idx(inode, 1);
     }
 
     return max;
 }
 
 static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext)
 {
     ext4_fsblk_t block = ext4_ext_pblock(ext);
     int len = ext4_ext_get_actual_len(ext);
     ext4_lblk_t lblock = le32_to_cpu(ext->ee_block);
 
     /*
      * We allow neither:
      *  - zero length
      *  - overflow/wrap-around
      */
     if (lblock + len <= lblock)
         return 0;
     return ext4_inode_block_valid(inode, block, len);
 }
 
 static int ext4_valid_extent_idx(struct inode *inode,
                 struct ext4_extent_idx *ext_idx)
 {
     ext4_fsblk_t block = ext4_idx_pblock(ext_idx);
 
     return ext4_inode_block_valid(inode, block, 1);
 }
 
 static int ext4_valid_extent_entries(struct inode *inode,
                      struct ext4_extent_header *eh,
                      ext4_lblk_t lblk, ext4_fsblk_t *pblk,
                      int depth)
 {
     unsigned short entries;
     ext4_lblk_t lblock = 0;
     ext4_lblk_t cur = 0;
 
     if (eh->eh_entries == 0)
         return 1;
 
     entries = le16_to_cpu(eh->eh_entries);
 
     if (depth == 0) {
         /* leaf entries */
         struct ext4_extent *ext = EXT_FIRST_EXTENT(eh);
 
         /*
          * The logical block in the first entry should equal to
          * the number in the index block.
          */
         if (depth != ext_depth(inode) &&
             lblk != le32_to_cpu(ext->ee_block))
             return 0;
         while (entries) {
             if (!ext4_valid_extent(inode, ext))
                 return 0;
 
             /* Check for overlapping extents */
             lblock = le32_to_cpu(ext->ee_block);
             if (lblock < cur) {
                 *pblk = ext4_ext_pblock(ext);
                 return 0;
             }
             cur = lblock + ext4_ext_get_actual_len(ext);
             ext++;
             entries--;
         }
     } else {
         struct ext4_extent_idx *ext_idx = EXT_FIRST_INDEX(eh);
 
         /*
          * The logical block in the first entry should equal to
          * the number in the parent index block.
          */
         if (depth != ext_depth(inode) &&
             lblk != le32_to_cpu(ext_idx->ei_block))
             return 0;
         while (entries) {
             if (!ext4_valid_extent_idx(inode, ext_idx))
                 return 0;
 
             /* Check for overlapping index extents */
             lblock = le32_to_cpu(ext_idx->ei_block);
             if (lblock < cur) {
                 *pblk = ext4_idx_pblock(ext_idx);
                 return 0;
             }
             ext_idx++;
             entries--;
             cur = lblock + 1;
         }
     }
     return 1;
 }
 
 static int __ext4_ext_check(const char *function, unsigned int line,
                 struct inode *inode, struct ext4_extent_header *eh,
                 int depth, ext4_fsblk_t pblk, ext4_lblk_t lblk)
 {
     const char *error_msg;
     int max = 0, err = -EFSCORRUPTED;
 
     if (unlikely(eh->eh_magic != EXT4_EXT_MAGIC)) {
         error_msg = "invalid magic";
         goto corrupted;
     }
     if (unlikely(le16_to_cpu(eh->eh_depth) != depth)) {
         error_msg = "unexpected eh_depth";
         goto corrupted;
     }
     if (unlikely(eh->eh_max == 0)) {
         error_msg = "invalid eh_max";
         goto corrupted;
     }
     max = ext4_ext_max_entries(inode, depth);
     if (unlikely(le16_to_cpu(eh->eh_max) > max)) {
         error_msg = "too large eh_max";
         goto corrupted;
     }
     if (unlikely(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max))) {
         error_msg = "invalid eh_entries";
         goto corrupted;
     }
     if (unlikely((eh->eh_entries == 0) && (depth > 0))) {
         error_msg = "eh_entries is 0 but eh_depth is > 0";
         goto corrupted;
     }
     if (!ext4_valid_extent_entries(inode, eh, lblk, &pblk, depth)) {
         error_msg = "invalid extent entries";
         goto corrupted;
     }
     if (unlikely(depth > 32)) {
         error_msg = "too large eh_depth";
         goto corrupted;
     }
     /* Verify checksum on non-root extent tree nodes */
     if (ext_depth(inode) != depth &&
         !ext4_extent_block_csum_verify(inode, eh)) {
         error_msg = "extent tree corrupted";
         err = -EFSBADCRC;
         goto corrupted;
     }
     return 0;
 
 corrupted:
     ext4_error_inode_err(inode, function, line, 0, -err,
                  "pblk %llu bad header/extent: %s - magic %x, "
                  "entries %u, max %u(%u), depth %u(%u)",
                  (unsigned long long) pblk, error_msg,
                  le16_to_cpu(eh->eh_magic),
                  le16_to_cpu(eh->eh_entries),
                  le16_to_cpu(eh->eh_max),
                  max, le16_to_cpu(eh->eh_depth), depth);
     return err;
 }
 
 #define ext4_ext_check(inode, eh, depth, pblk)          \
     __ext4_ext_check(__func__, __LINE__, (inode), (eh), (depth), (pblk), 0)
 
 int ext4_ext_check_inode(struct inode *inode)
 {
     return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode), 0);
 }
 
 static void ext4_cache_extents(struct inode *inode,
                    struct ext4_extent_header *eh)
 {
     struct ext4_extent *ex = EXT_FIRST_EXTENT(eh);
     ext4_lblk_t prev = 0;
     int i;
 
     for (i = le16_to_cpu(eh->eh_entries); i > 0; i--, ex++) {
         unsigned int status = EXTENT_STATUS_WRITTEN;
         ext4_lblk_t lblk = le32_to_cpu(ex->ee_block);
         int len = ext4_ext_get_actual_len(ex);
 
         if (prev && (prev != lblk))
             ext4_es_cache_extent(inode, prev, lblk - prev, ~0,
                          EXTENT_STATUS_HOLE);
 
         if (ext4_ext_is_unwritten(ex))
             status = EXTENT_STATUS_UNWRITTEN;
         ext4_es_cache_extent(inode, lblk, len,
                      ext4_ext_pblock(ex), status);
         prev = lblk + len;
     }
 }
 
 static struct buffer_head *
 __read_extent_tree_block(const char *function, unsigned int line,
              struct inode *inode, struct ext4_extent_idx *idx,
              int depth, int flags)
 {
     struct buffer_head      *bh;
     int             err;
     gfp_t               gfp_flags = __GFP_MOVABLE | GFP_NOFS;
     ext4_fsblk_t            pblk;
 
     if (flags & EXT4_EX_NOFAIL)
         gfp_flags |= __GFP_NOFAIL;
 
     pblk = ext4_idx_pblock(idx);
     bh = sb_getblk_gfp(inode->i_sb, pblk, gfp_flags);
     if (unlikely(!bh))
         return ERR_PTR(-ENOMEM);
 
     if (!bh_uptodate_or_lock(bh)) {
         trace_ext4_ext_load_extent(inode, pblk, _RET_IP_);
         err = ext4_read_bh(bh, 0, NULL);
         if (err < 0)
             goto errout;
     }
     if (buffer_verified(bh) && !(flags & EXT4_EX_FORCE_CACHE))
         return bh;
     err = __ext4_ext_check(function, line, inode, ext_block_hdr(bh),
                    depth, pblk, le32_to_cpu(idx->ei_block));
     if (err)
         goto errout;
     set_buffer_verified(bh);
     /*
      * If this is a leaf block, cache all of its entries
      */
     if (!(flags & EXT4_EX_NOCACHE) && depth == 0) {
         struct ext4_extent_header *eh = ext_block_hdr(bh);
         ext4_cache_extents(inode, eh);
     }
     return bh;
 errout:
     put_bh(bh);
     return ERR_PTR(err);
 
 }
 
 #define read_extent_tree_block(inode, idx, depth, flags)        \
     __read_extent_tree_block(__func__, __LINE__, (inode), (idx),    \
                  (depth), (flags))
 
 /*
  * This function is called to cache a file's extent information in the
  * extent status tree
  */
 int ext4_ext_precache(struct inode *inode)
 {
     struct ext4_inode_info *ei = EXT4_I(inode);
     struct ext4_ext_path *path = NULL;
     struct buffer_head *bh;
     int i = 0, depth, ret = 0;
 
     if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         return 0;   /* not an extent-mapped inode */
 
     down_read(&ei->i_data_sem);
     depth = ext_depth(inode);
 
     /* Don't cache anything if there are no external extent blocks */
     if (!depth) {
         up_read(&ei->i_data_sem);
         return ret;
     }
 
     path = kcalloc(depth + 1, sizeof(struct ext4_ext_path),
                GFP_NOFS);
     if (path == NULL) {
         up_read(&ei->i_data_sem);
         return -ENOMEM;
     }
 
     path[0].p_hdr = ext_inode_hdr(inode);
     ret = ext4_ext_check(inode, path[0].p_hdr, depth, 0);
     if (ret)
         goto out;
     path[0].p_idx = EXT_FIRST_INDEX(path[0].p_hdr);
     while (i >= 0) {
         /*
          * If this is a leaf block or we've reached the end of
          * the index block, go up
          */
         if ((i == depth) ||
             path[i].p_idx > EXT_LAST_INDEX(path[i].p_hdr)) {
             brelse(path[i].p_bh);
             path[i].p_bh = NULL;
             i--;
             continue;
         }
         bh = read_extent_tree_block(inode, path[i].p_idx++,
                         depth - i - 1,
                         EXT4_EX_FORCE_CACHE);
         if (IS_ERR(bh)) {
             ret = PTR_ERR(bh);
             break;
         }
         i++;
         path[i].p_bh = bh;
         path[i].p_hdr = ext_block_hdr(bh);
         path[i].p_idx = EXT_FIRST_INDEX(path[i].p_hdr);
     }
     ext4_set_inode_state(inode, EXT4_STATE_EXT_PRECACHED);
 out:
     up_read(&ei->i_data_sem);
     ext4_ext_drop_refs(path);
     kfree(path);
     return ret;
 }
 
 #ifdef EXT_DEBUG
 static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
 {
     int k, l = path->p_depth;
 
     ext_debug(inode, "path:");
     for (k = 0; k <= l; k++, path++) {
         if (path->p_idx) {
             ext_debug(inode, "  %d->%llu",
                   le32_to_cpu(path->p_idx->ei_block),
                   ext4_idx_pblock(path->p_idx));
         } else if (path->p_ext) {
             ext_debug(inode, "  %d:[%d]%d:%llu ",
                   le32_to_cpu(path->p_ext->ee_block),
                   ext4_ext_is_unwritten(path->p_ext),
                   ext4_ext_get_actual_len(path->p_ext),
                   ext4_ext_pblock(path->p_ext));
         } else
             ext_debug(inode, "  []");
     }
     ext_debug(inode, "\n");
 }
 
 static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
 {
     int depth = ext_depth(inode);
     struct ext4_extent_header *eh;
     struct ext4_extent *ex;
     int i;
 
     if (!path)
         return;
 
     eh = path[depth].p_hdr;
     ex = EXT_FIRST_EXTENT(eh);
 
     ext_debug(inode, "Displaying leaf extents\n");
 
     for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
         ext_debug(inode, "%d:[%d]%d:%llu ", le32_to_cpu(ex->ee_block),
               ext4_ext_is_unwritten(ex),
               ext4_ext_get_actual_len(ex), ext4_ext_pblock(ex));
     }
     ext_debug(inode, "\n");
 }
 
 static void ext4_ext_show_move(struct inode *inode, struct ext4_ext_path *path,
             ext4_fsblk_t newblock, int level)
 {
     int depth = ext_depth(inode);
     struct ext4_extent *ex;
 
     if (depth != level) {
         struct ext4_extent_idx *idx;
         idx = path[level].p_idx;
         while (idx <= EXT_MAX_INDEX(path[level].p_hdr)) {
             ext_debug(inode, "%d: move %d:%llu in new index %llu\n",
                   level, le32_to_cpu(idx->ei_block),
                   ext4_idx_pblock(idx), newblock);
             idx++;
         }
 
         return;
     }
 
     ex = path[depth].p_ext;
     while (ex <= EXT_MAX_EXTENT(path[depth].p_hdr)) {
         ext_debug(inode, "move %d:%llu:[%d]%d in new leaf %llu\n",
                 le32_to_cpu(ex->ee_block),
                 ext4_ext_pblock(ex),
                 ext4_ext_is_unwritten(ex),
                 ext4_ext_get_actual_len(ex),
                 newblock);
         ex++;
     }
 }
 
 #else
 #define ext4_ext_show_path(inode, path)
 #define ext4_ext_show_leaf(inode, path)
 #define ext4_ext_show_move(inode, path, newblock, level)
 #endif
 
 void ext4_ext_drop_refs(struct ext4_ext_path *path)
 {
     int depth, i;
 
     if (!path)
         return;
     depth = path->p_depth;
     for (i = 0; i <= depth; i++, path++) {
         brelse(path->p_bh);
         path->p_bh = NULL;
     }
 }
 
 /*
  * ext4_ext_binsearch_idx:
  * binary search for the closest index of the given block
  * the header must be checked before calling this
  */
 static void
 ext4_ext_binsearch_idx(struct inode *inode,
             struct ext4_ext_path *path, ext4_lblk_t block)
 {
     struct ext4_extent_header *eh = path->p_hdr;
     struct ext4_extent_idx *r, *l, *m;
 
 
     ext_debug(inode, "binsearch for %u(idx):  ", block);
 
     l = EXT_FIRST_INDEX(eh) + 1;
     r = EXT_LAST_INDEX(eh);
     while (l <= r) {
         m = l + (r - l) / 2;
         ext_debug(inode, "%p(%u):%p(%u):%p(%u) ", l,
               le32_to_cpu(l->ei_block), m, le32_to_cpu(m->ei_block),
               r, le32_to_cpu(r->ei_block));
 
         if (block < le32_to_cpu(m->ei_block))
             r = m - 1;
         else
             l = m + 1;
     }
 
     path->p_idx = l - 1;
     ext_debug(inode, "  -> %u->%lld ", le32_to_cpu(path->p_idx->ei_block),
           ext4_idx_pblock(path->p_idx));
 
 #ifdef CHECK_BINSEARCH
     {
         struct ext4_extent_idx *chix, *ix;
         int k;
 
         chix = ix = EXT_FIRST_INDEX(eh);
         for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ix++) {
             if (k != 0 && le32_to_cpu(ix->ei_block) <=
                 le32_to_cpu(ix[-1].ei_block)) {
                 printk(KERN_DEBUG "k=%d, ix=0x%p, "
                        "first=0x%p\n", k,
                        ix, EXT_FIRST_INDEX(eh));
                 printk(KERN_DEBUG "%u <= %u\n",
                        le32_to_cpu(ix->ei_block),
                        le32_to_cpu(ix[-1].ei_block));
             }
             BUG_ON(k && le32_to_cpu(ix->ei_block)
                        <= le32_to_cpu(ix[-1].ei_block));
             if (block < le32_to_cpu(ix->ei_block))
                 break;
             chix = ix;
         }
         BUG_ON(chix != path->p_idx);
     }
 #endif
 
 }
 
 /*
  * ext4_ext_binsearch:
  * binary search for closest extent of the given block
  * the header must be checked before calling this
  */
 static void
 ext4_ext_binsearch(struct inode *inode,
         struct ext4_ext_path *path, ext4_lblk_t block)
 {
     struct ext4_extent_header *eh = path->p_hdr;
     struct ext4_extent *r, *l, *m;
 
     if (eh->eh_entries == 0) {
         /*
          * this leaf is empty:
          * we get such a leaf in split/add case
          */
         return;
     }
 
     ext_debug(inode, "binsearch for %u:  ", block);
 
     l = EXT_FIRST_EXTENT(eh) + 1;
     r = EXT_LAST_EXTENT(eh);
 
     while (l <= r) {
         m = l + (r - l) / 2;
         ext_debug(inode, "%p(%u):%p(%u):%p(%u) ", l,
               le32_to_cpu(l->ee_block), m, le32_to_cpu(m->ee_block),
               r, le32_to_cpu(r->ee_block));
 
         if (block < le32_to_cpu(m->ee_block))
             r = m - 1;
         else
             l = m + 1;
     }
 
     path->p_ext = l - 1;
     ext_debug(inode, "  -> %d:%llu:[%d]%d ",
             le32_to_cpu(path->p_ext->ee_block),
             ext4_ext_pblock(path->p_ext),
             ext4_ext_is_unwritten(path->p_ext),
             ext4_ext_get_actual_len(path->p_ext));
 
 #ifdef CHECK_BINSEARCH
     {
         struct ext4_extent *chex, *ex;
         int k;
 
         chex = ex = EXT_FIRST_EXTENT(eh);
         for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
             BUG_ON(k && le32_to_cpu(ex->ee_block)
                       <= le32_to_cpu(ex[-1].ee_block));
             if (block < le32_to_cpu(ex->ee_block))
                 break;
             chex = ex;
         }
         BUG_ON(chex != path->p_ext);
     }
 #endif
 
 }
 
 void ext4_ext_tree_init(handle_t *handle, struct inode *inode)
 {
     struct ext4_extent_header *eh;
 
     eh = ext_inode_hdr(inode);
     eh->eh_depth = 0;
     eh->eh_entries = 0;
     eh->eh_magic = EXT4_EXT_MAGIC;
     eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
     eh->eh_generation = 0;
     ext4_mark_inode_dirty(handle, inode);
 }
 
 struct ext4_ext_path *
 ext4_find_extent(struct inode *inode, ext4_lblk_t block,
          struct ext4_ext_path **orig_path, int flags)
 {
     struct ext4_extent_header *eh;
     struct buffer_head *bh;
     struct ext4_ext_path *path = orig_path ? *orig_path : NULL;
     short int depth, i, ppos = 0;
     int ret;
     gfp_t gfp_flags = GFP_NOFS;
 
     if (flags & EXT4_EX_NOFAIL)
         gfp_flags |= __GFP_NOFAIL;
 
     eh = ext_inode_hdr(inode);
     depth = ext_depth(inode);
     if (depth < 0 || depth > EXT4_MAX_EXTENT_DEPTH) {
         EXT4_ERROR_INODE(inode, "inode has invalid extent depth: %d",
                  depth);
         ret = -EFSCORRUPTED;
         goto err;
     }
 
     if (path) {
         ext4_ext_drop_refs(path);
         if (depth > path[0].p_maxdepth) {
             kfree(path);
             *orig_path = path = NULL;
         }
     }
     if (!path) {
         /* account possible depth increase */
         path = kcalloc(depth + 2, sizeof(struct ext4_ext_path),
                 gfp_flags);
         if (unlikely(!path))
             return ERR_PTR(-ENOMEM);
         path[0].p_maxdepth = depth + 1;
     }
     path[0].p_hdr = eh;
     path[0].p_bh = NULL;
 
     i = depth;
     if (!(flags & EXT4_EX_NOCACHE) && depth == 0)
         ext4_cache_extents(inode, eh);
     /* walk through the tree */
     while (i) {
         ext_debug(inode, "depth %d: num %d, max %d\n",
               ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
 
         ext4_ext_binsearch_idx(inode, path + ppos, block);
         path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
         path[ppos].p_depth = i;
         path[ppos].p_ext = NULL;
 
         bh = read_extent_tree_block(inode, path[ppos].p_idx, --i, flags);
         if (IS_ERR(bh)) {
             ret = PTR_ERR(bh);
             goto err;
         }
 
         eh = ext_block_hdr(bh);
         ppos++;
         path[ppos].p_bh = bh;
         path[ppos].p_hdr = eh;
     }
 
     path[ppos].p_depth = i;
     path[ppos].p_ext = NULL;
     path[ppos].p_idx = NULL;
 
     /* find extent */
     ext4_ext_binsearch(inode, path + ppos, block);
     /* if not an empty leaf */
     if (path[ppos].p_ext)
         path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
 
     ext4_ext_show_path(inode, path);
 
     return path;
 
 err:
     ext4_ext_drop_refs(path);
     kfree(path);
     if (orig_path)
         *orig_path = NULL;
     return ERR_PTR(ret);
 }
 
 /*
  * ext4_ext_insert_index:
  * insert new index [@logical;@ptr] into the block at @curp;
  * check where to insert: before @curp or after @curp
  */
 static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
                  struct ext4_ext_path *curp,
                  int logical, ext4_fsblk_t ptr)
 {
     struct ext4_extent_idx *ix;
     int len, err;
 
     err = ext4_ext_get_access(handle, inode, curp);
     if (err)
         return err;
 
     if (unlikely(logical == le32_to_cpu(curp->p_idx->ei_block))) {
         EXT4_ERROR_INODE(inode,
                  "logical %d == ei_block %d!",
                  logical, le32_to_cpu(curp->p_idx->ei_block));
         return -EFSCORRUPTED;
     }
 
     if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
                  >= le16_to_cpu(curp->p_hdr->eh_max))) {
         EXT4_ERROR_INODE(inode,
                  "eh_entries %d >= eh_max %d!",
                  le16_to_cpu(curp->p_hdr->eh_entries),
                  le16_to_cpu(curp->p_hdr->eh_max));
         return -EFSCORRUPTED;
     }
 
     if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
         /* insert after */
         ext_debug(inode, "insert new index %d after: %llu\n",
               logical, ptr);
         ix = curp->p_idx + 1;
     } else {
         /* insert before */
         ext_debug(inode, "insert new index %d before: %llu\n",
               logical, ptr);
         ix = curp->p_idx;
     }
 
     len = EXT_LAST_INDEX(curp->p_hdr) - ix + 1;
     BUG_ON(len < 0);
     if (len > 0) {
         ext_debug(inode, "insert new index %d: "
                 "move %d indices from 0x%p to 0x%p\n",
                 logical, len, ix, ix + 1);
         memmove(ix + 1, ix, len * sizeof(struct ext4_extent_idx));
     }
 
     if (unlikely(ix > EXT_MAX_INDEX(curp->p_hdr))) {
         EXT4_ERROR_INODE(inode, "ix > EXT_MAX_INDEX!");
         return -EFSCORRUPTED;
     }
 
     ix->ei_block = cpu_to_le32(logical);
     ext4_idx_store_pblock(ix, ptr);
     le16_add_cpu(&curp->p_hdr->eh_entries, 1);
 
     if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
         EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
         return -EFSCORRUPTED;
     }
 
     err = ext4_ext_dirty(handle, inode, curp);
     ext4_std_error(inode->i_sb, err);
 
     return err;
 }
 
 /*
  * ext4_ext_split:
  * inserts new subtree into the path, using free index entry
  * at depth @at:
  * - allocates all needed blocks (new leaf and all intermediate index blocks)
  * - makes decision where to split
  * - moves remaining extents and index entries (right to the split point)
  *   into the newly allocated blocks
  * - initializes subtree
  */
 static int ext4_ext_split(handle_t *handle, struct inode *inode,
               unsigned int flags,
               struct ext4_ext_path *path,
               struct ext4_extent *newext, int at)
 {
     struct buffer_head *bh = NULL;
     int depth = ext_depth(inode);
     struct ext4_extent_header *neh;
     struct ext4_extent_idx *fidx;
     int i = at, k, m, a;
     ext4_fsblk_t newblock, oldblock;
     __le32 border;
     ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
     gfp_t gfp_flags = GFP_NOFS;
     int err = 0;
     size_t ext_size = 0;
 
     if (flags & EXT4_EX_NOFAIL)
         gfp_flags |= __GFP_NOFAIL;
 
     /* make decision: where to split? */
     /* FIXME: now decision is simplest: at current extent */
 
     /* if current leaf will be split, then we should use
      * border from split point */
     if (unlikely(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr))) {
         EXT4_ERROR_INODE(inode, "p_ext > EXT_MAX_EXTENT!");
         return -EFSCORRUPTED;
     }
     if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
         border = path[depth].p_ext[1].ee_block;
         ext_debug(inode, "leaf will be split."
                 " next leaf starts at %d\n",
                   le32_to_cpu(border));
     } else {
         border = newext->ee_block;
         ext_debug(inode, "leaf will be added."
                 " next leaf starts at %d\n",
                 le32_to_cpu(border));
     }
 
     /*
      * If error occurs, then we break processing
      * and mark filesystem read-only. index won't
      * be inserted and tree will be in consistent
      * state. Next mount will repair buffers too.
      */
 
     /*
      * Get array to track all allocated blocks.
      * We need this to handle errors and free blocks
      * upon them.
      */
     ablocks = kcalloc(depth, sizeof(ext4_fsblk_t), gfp_flags);
     if (!ablocks)
         return -ENOMEM;
 
     /* allocate all needed blocks */
     ext_debug(inode, "allocate %d blocks for indexes/leaf\n", depth - at);
     for (a = 0; a < depth - at; a++) {
         newblock = ext4_ext_new_meta_block(handle, inode, path,
                            newext, &err, flags);
         if (newblock == 0)
             goto cleanup;
         ablocks[a] = newblock;
     }
 
     /* initialize new leaf */
     newblock = ablocks[--a];
     if (unlikely(newblock == 0)) {
         EXT4_ERROR_INODE(inode, "newblock == 0!");
         err = -EFSCORRUPTED;
         goto cleanup;
     }
     bh = sb_getblk_gfp(inode->i_sb, newblock, __GFP_MOVABLE | GFP_NOFS);
     if (unlikely(!bh)) {
         err = -ENOMEM;
         goto cleanup;
     }
     lock_buffer(bh);
 
     err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
                          EXT4_JTR_NONE);
     if (err)
         goto cleanup;
 
     neh = ext_block_hdr(bh);
     neh->eh_entries = 0;
     neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
     neh->eh_magic = EXT4_EXT_MAGIC;
     neh->eh_depth = 0;
     neh->eh_generation = 0;
 
     /* move remainder of path[depth] to the new leaf */
     if (unlikely(path[depth].p_hdr->eh_entries !=
              path[depth].p_hdr->eh_max)) {
         EXT4_ERROR_INODE(inode, "eh_entries %d != eh_max %d!",
                  path[depth].p_hdr->eh_entries,
                  path[depth].p_hdr->eh_max);
         err = -EFSCORRUPTED;
         goto cleanup;
     }
     /* start copy from next extent */
     m = EXT_MAX_EXTENT(path[depth].p_hdr) - path[depth].p_ext++;
     ext4_ext_show_move(inode, path, newblock, depth);
     if (m) {
         struct ext4_extent *ex;
         ex = EXT_FIRST_EXTENT(neh);
         memmove(ex, path[depth].p_ext, sizeof(struct ext4_extent) * m);
         le16_add_cpu(&neh->eh_entries, m);
     }
 
     /* zero out unused area in the extent block */
     ext_size = sizeof(struct ext4_extent_header) +
         sizeof(struct ext4_extent) * le16_to_cpu(neh->eh_entries);
     memset(bh->b_data + ext_size, 0, inode->i_sb->s_blocksize - ext_size);
     ext4_extent_block_csum_set(inode, neh);
     set_buffer_uptodate(bh);
     unlock_buffer(bh);
 
     err = ext4_handle_dirty_metadata(handle, inode, bh);
     if (err)
         goto cleanup;
     brelse(bh);
     bh = NULL;
 
     /* correct old leaf */
     if (m) {
         err = ext4_ext_get_access(handle, inode, path + depth);
         if (err)
             goto cleanup;
         le16_add_cpu(&path[depth].p_hdr->eh_entries, -m);
         err = ext4_ext_dirty(handle, inode, path + depth);
         if (err)
             goto cleanup;
 
     }
 
     /* create intermediate indexes */
     k = depth - at - 1;
     if (unlikely(k < 0)) {
         EXT4_ERROR_INODE(inode, "k %d < 0!", k);
         err = -EFSCORRUPTED;
         goto cleanup;
     }
     if (k)
         ext_debug(inode, "create %d intermediate indices\n", k);
     /* insert new index into current index block */
     /* current depth stored in i var */
     i = depth - 1;
     while (k--) {
         oldblock = newblock;
         newblock = ablocks[--a];
         bh = sb_getblk(inode->i_sb, newblock);
         if (unlikely(!bh)) {
             err = -ENOMEM;
             goto cleanup;
         }
         lock_buffer(bh);
 
         err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
                              EXT4_JTR_NONE);
         if (err)
             goto cleanup;
 
         neh = ext_block_hdr(bh);
         neh->eh_entries = cpu_to_le16(1);
         neh->eh_magic = EXT4_EXT_MAGIC;
         neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
         neh->eh_depth = cpu_to_le16(depth - i);
         neh->eh_generation = 0;
         fidx = EXT_FIRST_INDEX(neh);
         fidx->ei_block = border;
         ext4_idx_store_pblock(fidx, oldblock);
 
         ext_debug(inode, "int.index at %d (block %llu): %u -> %llu\n",
                 i, newblock, le32_to_cpu(border), oldblock);
 
         /* move remainder of path[i] to the new index block */
         if (unlikely(EXT_MAX_INDEX(path[i].p_hdr) !=
                     EXT_LAST_INDEX(path[i].p_hdr))) {
             EXT4_ERROR_INODE(inode,
                      "EXT_MAX_INDEX != EXT_LAST_INDEX ee_block %d!",
                      le32_to_cpu(path[i].p_ext->ee_block));
             err = -EFSCORRUPTED;
             goto cleanup;
         }
         /* start copy indexes */
         m = EXT_MAX_INDEX(path[i].p_hdr) - path[i].p_idx++;
         ext_debug(inode, "cur 0x%p, last 0x%p\n", path[i].p_idx,
                 EXT_MAX_INDEX(path[i].p_hdr));
         ext4_ext_show_move(inode, path, newblock, i);
         if (m) {
             memmove(++fidx, path[i].p_idx,
                 sizeof(struct ext4_extent_idx) * m);
             le16_add_cpu(&neh->eh_entries, m);
         }
         /* zero out unused area in the extent block */
         ext_size = sizeof(struct ext4_extent_header) +
            (sizeof(struct ext4_extent) * le16_to_cpu(neh->eh_entries));
         memset(bh->b_data + ext_size, 0,
             inode->i_sb->s_blocksize - ext_size);
         ext4_extent_block_csum_set(inode, neh);
         set_buffer_uptodate(bh);
         unlock_buffer(bh);
 
         err = ext4_handle_dirty_metadata(handle, inode, bh);
         if (err)
             goto cleanup;
         brelse(bh);
         bh = NULL;
 
         /* correct old index */
         if (m) {
             err = ext4_ext_get_access(handle, inode, path + i);
             if (err)
                 goto cleanup;
             le16_add_cpu(&path[i].p_hdr->eh_entries, -m);
             err = ext4_ext_dirty(handle, inode, path + i);
             if (err)
                 goto cleanup;
         }
 
         i--;
     }
 
     /* insert new index */
     err = ext4_ext_insert_index(handle, inode, path + at,
                     le32_to_cpu(border), newblock);
 
 cleanup:
     if (bh) {
         if (buffer_locked(bh))
             unlock_buffer(bh);
         brelse(bh);
     }
 
     if (err) {
         /* free all allocated blocks in error case */
         for (i = 0; i < depth; i++) {
             if (!ablocks[i])
                 continue;
             ext4_free_blocks(handle, inode, NULL, ablocks[i], 1,
                      EXT4_FREE_BLOCKS_METADATA);
         }
     }
     kfree(ablocks);
 
     return err;
 }
 
 /*
  * ext4_ext_grow_indepth:
  * implements tree growing procedure:
  * - allocates new block
  * - moves top-level data (index block or leaf) into the new block
  * - initializes new top-level, creating index that points to the
  *   just created block
  */
 static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
                  unsigned int flags)
 {
     struct ext4_extent_header *neh;
     struct buffer_head *bh;
     ext4_fsblk_t newblock, goal = 0;
     struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
     int err = 0;
     size_t ext_size = 0;
 
     /* Try to prepend new index to old one */
     if (ext_depth(inode))
         goal = ext4_idx_pblock(EXT_FIRST_INDEX(ext_inode_hdr(inode)));
     if (goal > le32_to_cpu(es->s_first_data_block)) {
         flags |= EXT4_MB_HINT_TRY_GOAL;
         goal--;
     } else
         goal = ext4_inode_to_goal_block(inode);
     newblock = ext4_new_meta_blocks(handle, inode, goal, flags,
                     NULL, &err);
     if (newblock == 0)
         return err;
 
     bh = sb_getblk_gfp(inode->i_sb, newblock, __GFP_MOVABLE | GFP_NOFS);
     if (unlikely(!bh))
         return -ENOMEM;
     lock_buffer(bh);
 
     err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
                          EXT4_JTR_NONE);
     if (err) {
         unlock_buffer(bh);
         goto out;
     }
 
     ext_size = sizeof(EXT4_I(inode)->i_data);
     /* move top-level index/leaf into new block */
     memmove(bh->b_data, EXT4_I(inode)->i_data, ext_size);
     /* zero out unused area in the extent block */
     memset(bh->b_data + ext_size, 0, inode->i_sb->s_blocksize - ext_size);
 
     /* set size of new block */
     neh = ext_block_hdr(bh);
     /* old root could have indexes or leaves
      * so calculate e_max right way */
     if (ext_depth(inode))
         neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
     else
         neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
     neh->eh_magic = EXT4_EXT_MAGIC;
     ext4_extent_block_csum_set(inode, neh);
     set_buffer_uptodate(bh);
     set_buffer_verified(bh);
     unlock_buffer(bh);
 
     err = ext4_handle_dirty_metadata(handle, inode, bh);
     if (err)
         goto out;
 
     /* Update top-level index: num,max,pointer */
     neh = ext_inode_hdr(inode);
     neh->eh_entries = cpu_to_le16(1);
     ext4_idx_store_pblock(EXT_FIRST_INDEX(neh), newblock);
     if (neh->eh_depth == 0) {
         /* Root extent block becomes index block */
         neh->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
         EXT_FIRST_INDEX(neh)->ei_block =
             EXT_FIRST_EXTENT(neh)->ee_block;
     }
     ext_debug(inode, "new root: num %d(%d), lblock %d, ptr %llu\n",
           le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),
           le32_to_cpu(EXT_FIRST_INDEX(neh)->ei_block),
           ext4_idx_pblock(EXT_FIRST_INDEX(neh)));
 
     le16_add_cpu(&neh->eh_depth, 1);
     err = ext4_mark_inode_dirty(handle, inode);
 out:
     brelse(bh);
 
     return err;
 }
 
 /*
  * ext4_ext_create_new_leaf:
  * finds empty index and adds new leaf.
  * if no free index is found, then it requests in-depth growing.
  */
 static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
                     unsigned int mb_flags,
                     unsigned int gb_flags,
                     struct ext4_ext_path **ppath,
                     struct ext4_extent *newext)
 {
     struct ext4_ext_path *path = *ppath;
     struct ext4_ext_path *curp;
     int depth, i, err = 0;
 
 repeat:
     i = depth = ext_depth(inode);
 
     /* walk up to the tree and look for free index entry */
     curp = path + depth;
     while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
         i--;
         curp--;
     }
 
     /* we use already allocated block for index block,
      * so subsequent data blocks should be contiguous */
     if (EXT_HAS_FREE_INDEX(curp)) {
         /* if we found index with free entry, then use that
          * entry: create all needed subtree and add new leaf */
         err = ext4_ext_split(handle, inode, mb_flags, path, newext, i);
         if (err)
             goto out;
 
         /* refill path */
         path = ext4_find_extent(inode,
                     (ext4_lblk_t)le32_to_cpu(newext->ee_block),
                     ppath, gb_flags);
         if (IS_ERR(path))
             err = PTR_ERR(path);
     } else {
         /* tree is full, time to grow in depth */
         err = ext4_ext_grow_indepth(handle, inode, mb_flags);
         if (err)
             goto out;
 
         /* refill path */
         path = ext4_find_extent(inode,
                    (ext4_lblk_t)le32_to_cpu(newext->ee_block),
                     ppath, gb_flags);
         if (IS_ERR(path)) {
             err = PTR_ERR(path);
             goto out;
         }
 
         /*
          * only first (depth 0 -> 1) produces free space;
          * in all other cases we have to split the grown tree
          */
         depth = ext_depth(inode);
         if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
             /* now we need to split */
             goto repeat;
         }
     }
 
 out:
     return err;
 }
 
 /*
  * search the closest allocated block to the left for *logical
  * and returns it at @logical + it's physical address at @phys
  * if *logical is the smallest allocated block, the function
  * returns 0 at @phys
  * return value contains 0 (success) or error code
  */
 static int ext4_ext_search_left(struct inode *inode,
                 struct ext4_ext_path *path,
                 ext4_lblk_t *logical, ext4_fsblk_t *phys)
 {
     struct ext4_extent_idx *ix;
     struct ext4_extent *ex;
     int depth, ee_len;
 
     if (unlikely(path == NULL)) {
         EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
         return -EFSCORRUPTED;
     }
     depth = path->p_depth;
     *phys = 0;
 
     if (depth == 0 && path->p_ext == NULL)
         return 0;
 
     /* usually extent in the path covers blocks smaller
      * then *logical, but it can be that extent is the
      * first one in the file */
 
     ex = path[depth].p_ext;
     ee_len = ext4_ext_get_actual_len(ex);
     if (*logical < le32_to_cpu(ex->ee_block)) {
         if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
             EXT4_ERROR_INODE(inode,
                      "EXT_FIRST_EXTENT != ex *logical %d ee_block %d!",
                      *logical, le32_to_cpu(ex->ee_block));
             return -EFSCORRUPTED;
         }
         while (--depth >= 0) {
             ix = path[depth].p_idx;
             if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
                 EXT4_ERROR_INODE(inode,
                   "ix (%d) != EXT_FIRST_INDEX (%d) (depth %d)!",
                   ix != NULL ? le32_to_cpu(ix->ei_block) : 0,
                   le32_to_cpu(EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block),
                   depth);
                 return -EFSCORRUPTED;
             }
         }
         return 0;
     }
 
     if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
         EXT4_ERROR_INODE(inode,
                  "logical %d < ee_block %d + ee_len %d!",
                  *logical, le32_to_cpu(ex->ee_block), ee_len);
         return -EFSCORRUPTED;
     }
 
     *logical = le32_to_cpu(ex->ee_block) + ee_len - 1;
     *phys = ext4_ext_pblock(ex) + ee_len - 1;
     return 0;
 }
 
 /*
  * Search the closest allocated block to the right for *logical
  * and returns it at @logical + it's physical address at @phys.
  * If not exists, return 0 and @phys is set to 0. We will return
  * 1 which means we found an allocated block and ret_ex is valid.
  * Or return a (< 0) error code.
  */
 static int ext4_ext_search_right(struct inode *inode,
                  struct ext4_ext_path *path,
                  ext4_lblk_t *logical, ext4_fsblk_t *phys,
                  struct ext4_extent *ret_ex)
 {
     struct buffer_head *bh = NULL;
     struct ext4_extent_header *eh;
     struct ext4_extent_idx *ix;
     struct ext4_extent *ex;
     int depth;  /* Note, NOT eh_depth; depth from top of tree */
     int ee_len;
 
     if (unlikely(path == NULL)) {
         EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
         return -EFSCORRUPTED;
     }
     depth = path->p_depth;
     *phys = 0;
 
     if (depth == 0 && path->p_ext == NULL)
         return 0;
 
     /* usually extent in the path covers blocks smaller
      * then *logical, but it can be that extent is the
      * first one in the file */
 
     ex = path[depth].p_ext;
     ee_len = ext4_ext_get_actual_len(ex);
     if (*logical < le32_to_cpu(ex->ee_block)) {
         if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
             EXT4_ERROR_INODE(inode,
                      "first_extent(path[%d].p_hdr) != ex",
                      depth);
             return -EFSCORRUPTED;
         }
         while (--depth >= 0) {
             ix = path[depth].p_idx;
             if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
                 EXT4_ERROR_INODE(inode,
                          "ix != EXT_FIRST_INDEX *logical %d!",
                          *logical);
                 return -EFSCORRUPTED;
             }
         }
         goto found_extent;
     }
 
     if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
         EXT4_ERROR_INODE(inode,
                  "logical %d < ee_block %d + ee_len %d!",
                  *logical, le32_to_cpu(ex->ee_block), ee_len);
         return -EFSCORRUPTED;
     }
 
     if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
         /* next allocated block in this leaf */
         ex++;
         goto found_extent;
     }
 
     /* go up and search for index to the right */
     while (--depth >= 0) {
         ix = path[depth].p_idx;
         if (ix != EXT_LAST_INDEX(path[depth].p_hdr))
             goto got_index;
     }
 
     /* we've gone up to the root and found no index to the right */
     return 0;
 
 got_index:
     /* we've found index to the right, let's
      * follow it and find the closest allocated
      * block to the right */
     ix++;
     while (++depth < path->p_depth) {
         /* subtract from p_depth to get proper eh_depth */
         bh = read_extent_tree_block(inode, ix, path->p_depth - depth, 0);
         if (IS_ERR(bh))
             return PTR_ERR(bh);
         eh = ext_block_hdr(bh);
         ix = EXT_FIRST_INDEX(eh);
         put_bh(bh);
     }
 
     bh = read_extent_tree_block(inode, ix, path->p_depth - depth, 0);
     if (IS_ERR(bh))
         return PTR_ERR(bh);
     eh = ext_block_hdr(bh);
     ex = EXT_FIRST_EXTENT(eh);
 found_extent:
     *logical = le32_to_cpu(ex->ee_block);
     *phys = ext4_ext_pblock(ex);
     if (ret_ex)
         *ret_ex = *ex;
     if (bh)
         put_bh(bh);
     return 1;
 }
 
 /*
  * ext4_ext_next_allocated_block:
  * returns allocated block in subsequent extent or EXT_MAX_BLOCKS.
  * NOTE: it considers block number from index entry as
  * allocated block. Thus, index entries have to be consistent
  * with leaves.
  */
 ext4_lblk_t
 ext4_ext_next_allocated_block(struct ext4_ext_path *path)
 {
     int depth;
 
     BUG_ON(path == NULL);
     depth = path->p_depth;
 
     if (depth == 0 && path->p_ext == NULL)
         return EXT_MAX_BLOCKS;
 
     while (depth >= 0) {
         struct ext4_ext_path *p = &path[depth];
 
         if (depth == path->p_depth) {
             /* leaf */
             if (p->p_ext && p->p_ext != EXT_LAST_EXTENT(p->p_hdr))
                 return le32_to_cpu(p->p_ext[1].ee_block);
         } else {
             /* index */
             if (p->p_idx != EXT_LAST_INDEX(p->p_hdr))
                 return le32_to_cpu(p->p_idx[1].ei_block);
         }
         depth--;
     }
 
     return EXT_MAX_BLOCKS;
 }
 
 /*
  * ext4_ext_next_leaf_block:
  * returns first allocated block from next leaf or EXT_MAX_BLOCKS
  */
 static ext4_lblk_t ext4_ext_next_leaf_block(struct ext4_ext_path *path)
 {
     int depth;
 
     BUG_ON(path == NULL);
     depth = path->p_depth;
 
     /* zero-tree has no leaf blocks at all */
     if (depth == 0)
         return EXT_MAX_BLOCKS;
 
     /* go to index block */
     depth--;
 
     while (depth >= 0) {
         if (path[depth].p_idx !=
                 EXT_LAST_INDEX(path[depth].p_hdr))
             return (ext4_lblk_t)
                 le32_to_cpu(path[depth].p_idx[1].ei_block);
         depth--;
     }
 
     return EXT_MAX_BLOCKS;
 }
 
 /*
  * ext4_ext_correct_indexes:
  * if leaf gets modified and modified extent is first in the leaf,
  * then we have to correct all indexes above.
  * TODO: do we need to correct tree in all cases?
  */
 static int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode,
                 struct ext4_ext_path *path)
 {
     struct ext4_extent_header *eh;
     int depth = ext_depth(inode);
     struct ext4_extent *ex;
     __le32 border;
     int k, err = 0;
 
     eh = path[depth].p_hdr;
     ex = path[depth].p_ext;
 
     if (unlikely(ex == NULL || eh == NULL)) {
         EXT4_ERROR_INODE(inode,
                  "ex %p == NULL or eh %p == NULL", ex, eh);
         return -EFSCORRUPTED;
     }
 
     if (depth == 0) {
         /* there is no tree at all */
         return 0;
     }
 
     if (ex != EXT_FIRST_EXTENT(eh)) {
         /* we correct tree if first leaf got modified only */
         return 0;
     }
 
     /*
      * TODO: we need correction if border is smaller than current one
      */
     k = depth - 1;
     border = path[depth].p_ext->ee_block;
     err = ext4_ext_get_access(handle, inode, path + k);
     if (err)
         return err;
     path[k].p_idx->ei_block = border;
     err = ext4_ext_dirty(handle, inode, path + k);
     if (err)
         return err;
 
     while (k--) {
         /* change all left-side indexes */
         if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
             break;
         err = ext4_ext_get_access(handle, inode, path + k);
         if (err)
             break;
         path[k].p_idx->ei_block = border;
         err = ext4_ext_dirty(handle, inode, path + k);
         if (err)
             break;
     }
 
     return err;
 }
 
 static int ext4_can_extents_be_merged(struct inode *inode,
                       struct ext4_extent *ex1,
                       struct ext4_extent *ex2)
 {
     unsigned short ext1_ee_len, ext2_ee_len;
 
     if (ext4_ext_is_unwritten(ex1) != ext4_ext_is_unwritten(ex2))
         return 0;
 
     ext1_ee_len = ext4_ext_get_actual_len(ex1);
     ext2_ee_len = ext4_ext_get_actual_len(ex2);
 
     if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
             le32_to_cpu(ex2->ee_block))
         return 0;
 
     if (ext1_ee_len + ext2_ee_len > EXT_INIT_MAX_LEN)
         return 0;
 
     if (ext4_ext_is_unwritten(ex1) &&
         ext1_ee_len + ext2_ee_len > EXT_UNWRITTEN_MAX_LEN)
         return 0;
 #ifdef AGGRESSIVE_TEST
     if (ext1_ee_len >= 4)
         return 0;
 #endif
 
     if (ext4_ext_pblock(ex1) + ext1_ee_len == ext4_ext_pblock(ex2))
         return 1;
     return 0;
 }
 
 /*
  * This function tries to merge the "ex" extent to the next extent in the tree.
  * It always tries to merge towards right. If you want to merge towards
  * left, pass "ex - 1" as argument instead of "ex".
  * Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
  * 1 if they got merged.
  */
 static int ext4_ext_try_to_merge_right(struct inode *inode,
                  struct ext4_ext_path *path,
                  struct ext4_extent *ex)
 {
     struct ext4_extent_header *eh;
     unsigned int depth, len;
     int merge_done = 0, unwritten;
 
     depth = ext_depth(inode);
     BUG_ON(path[depth].p_hdr == NULL);
     eh = path[depth].p_hdr;
 
     while (ex < EXT_LAST_EXTENT(eh)) {
         if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
             break;
         /* merge with next extent! */
         unwritten = ext4_ext_is_unwritten(ex);
         ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
                 + ext4_ext_get_actual_len(ex + 1));
         if (unwritten)
             ext4_ext_mark_unwritten(ex);
 
         if (ex + 1 < EXT_LAST_EXTENT(eh)) {
             len = (EXT_LAST_EXTENT(eh) - ex - 1)
                 * sizeof(struct ext4_extent);
             memmove(ex + 1, ex + 2, len);
         }
         le16_add_cpu(&eh->eh_entries, -1);
         merge_done = 1;
         WARN_ON(eh->eh_entries == 0);
         if (!eh->eh_entries)
             EXT4_ERROR_INODE(inode, "eh->eh_entries = 0!");
     }
 
     return merge_done;
 }
 
 /*
  * This function does a very simple check to see if we can collapse
  * an extent tree with a single extent tree leaf block into the inode.
  */
 static void ext4_ext_try_to_merge_up(handle_t *handle,
                      struct inode *inode,
                      struct ext4_ext_path *path)
 {
     size_t s;
     unsigned max_root = ext4_ext_space_root(inode, 0);
     ext4_fsblk_t blk;
 
     if ((path[0].p_depth != 1) ||
         (le16_to_cpu(path[0].p_hdr->eh_entries) != 1) ||
         (le16_to_cpu(path[1].p_hdr->eh_entries) > max_root))
         return;
 
     /*
      * We need to modify the block allocation bitmap and the block
      * group descriptor to release the extent tree block.  If we
      * can't get the journal credits, give up.
      */
     if (ext4_journal_extend(handle, 2,
             ext4_free_metadata_revoke_credits(inode->i_sb, 1)))
         return;
 
     /*
      * Copy the extent data up to the inode
      */
     blk = ext4_idx_pblock(path[0].p_idx);
     s = le16_to_cpu(path[1].p_hdr->eh_entries) *
         sizeof(struct ext4_extent_idx);
     s += sizeof(struct ext4_extent_header);
 
     path[1].p_maxdepth = path[0].p_maxdepth;
     memcpy(path[0].p_hdr, path[1].p_hdr, s);
     path[0].p_depth = 0;
     path[0].p_ext = EXT_FIRST_EXTENT(path[0].p_hdr) +
         (path[1].p_ext - EXT_FIRST_EXTENT(path[1].p_hdr));
     path[0].p_hdr->eh_max = cpu_to_le16(max_root);
 
     brelse(path[1].p_bh);
     ext4_free_blocks(handle, inode, NULL, blk, 1,
              EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
 }
 
 /*
  * This function tries to merge the @ex extent to neighbours in the tree, then
  * tries to collapse the extent tree into the inode.
  */
 static void ext4_ext_try_to_merge(handle_t *handle,
                   struct inode *inode,
                   struct ext4_ext_path *path,
                   struct ext4_extent *ex)
 {
     struct ext4_extent_header *eh;
     unsigned int depth;
     int merge_done = 0;
 
     depth = ext_depth(inode);
     BUG_ON(path[depth].p_hdr == NULL);
     eh = path[depth].p_hdr;
 
     if (ex > EXT_FIRST_EXTENT(eh))
         merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);
 
     if (!merge_done)
         (void) ext4_ext_try_to_merge_right(inode, path, ex);
 
     ext4_ext_try_to_merge_up(handle, inode, path);
 }
 
 /*
  * check if a portion of the "newext" extent overlaps with an
  * existing extent.
  *
  * If there is an overlap discovered, it updates the length of the newext
  * such that there will be no overlap, and then returns 1.
  * If there is no overlap found, it returns 0.
  */
 static unsigned int ext4_ext_check_overlap(struct ext4_sb_info *sbi,
                        struct inode *inode,
                        struct ext4_extent *newext,
                        struct ext4_ext_path *path)
 {
     ext4_lblk_t b1, b2;
     unsigned int depth, len1;
     unsigned int ret = 0;
 
     b1 = le32_to_cpu(newext->ee_block);
     len1 = ext4_ext_get_actual_len(newext);
     depth = ext_depth(inode);
     if (!path[depth].p_ext)
         goto out;
     b2 = EXT4_LBLK_CMASK(sbi, le32_to_cpu(path[depth].p_ext->ee_block));
 
     /*
      * get the next allocated block if the extent in the path
      * is before the requested block(s)
      */
     if (b2 < b1) {
         b2 = ext4_ext_next_allocated_block(path);
         if (b2 == EXT_MAX_BLOCKS)
             goto out;
         b2 = EXT4_LBLK_CMASK(sbi, b2);
     }
 
     /* check for wrap through zero on extent logical start block*/
     if (b1 + len1 < b1) {
         len1 = EXT_MAX_BLOCKS - b1;
         newext->ee_len = cpu_to_le16(len1);
         ret = 1;
     }
 
     /* check for overlap */
     if (b1 + len1 > b2) {
         newext->ee_len = cpu_to_le16(b2 - b1);
         ret = 1;
     }
 out:
     return ret;
 }
 
 /*
  * ext4_ext_insert_extent:
  * tries to merge requested extent into the existing extent or
  * inserts requested extent as new one into the tree,
  * creating new leaf in the no-space case.
  */
 int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
                 struct ext4_ext_path **ppath,
                 struct ext4_extent *newext, int gb_flags)
 {
     struct ext4_ext_path *path = *ppath;
     struct ext4_extent_header *eh;
     struct ext4_extent *ex, *fex;
     struct ext4_extent *nearex; /* nearest extent */
     struct ext4_ext_path *npath = NULL;
     int depth, len, err;
     ext4_lblk_t next;
     int mb_flags = 0, unwritten;
 
     if (gb_flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
         mb_flags |= EXT4_MB_DELALLOC_RESERVED;
     if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
         EXT4_ERROR_INODE(inode, "ext4_ext_get_actual_len(newext) == 0");
         return -EFSCORRUPTED;
     }
     depth = ext_depth(inode);
     ex = path[depth].p_ext;
     eh = path[depth].p_hdr;
     if (unlikely(path[depth].p_hdr == NULL)) {
         EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
         return -EFSCORRUPTED;
     }
 
     /* try to insert block into found extent and return */
     if (ex && !(gb_flags & EXT4_GET_BLOCKS_PRE_IO)) {
 
         /*
          * Try to see whether we should rather test the extent on
          * right from ex, or from the left of ex. This is because
          * ext4_find_extent() can return either extent on the
          * left, or on the right from the searched position. This
          * will make merging more effective.
          */
         if (ex < EXT_LAST_EXTENT(eh) &&
             (le32_to_cpu(ex->ee_block) +
             ext4_ext_get_actual_len(ex) <
             le32_to_cpu(newext->ee_block))) {
             ex += 1;
             goto prepend;
         } else if ((ex > EXT_FIRST_EXTENT(eh)) &&
                (le32_to_cpu(newext->ee_block) +
                ext4_ext_get_actual_len(newext) <
                le32_to_cpu(ex->ee_block)))
             ex -= 1;
 
         /* Try to append newex to the ex */
         if (ext4_can_extents_be_merged(inode, ex, newext)) {
             ext_debug(inode, "append [%d]%d block to %u:[%d]%d"
                   "(from %llu)\n",
                   ext4_ext_is_unwritten(newext),
                   ext4_ext_get_actual_len(newext),
                   le32_to_cpu(ex->ee_block),
                   ext4_ext_is_unwritten(ex),
                   ext4_ext_get_actual_len(ex),
                   ext4_ext_pblock(ex));
             err = ext4_ext_get_access(handle, inode,
                           path + depth);
             if (err)
                 return err;
             unwritten = ext4_ext_is_unwritten(ex);
             ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
                     + ext4_ext_get_actual_len(newext));
             if (unwritten)
                 ext4_ext_mark_unwritten(ex);
             nearex = ex;
             goto merge;
         }
 
 prepend:
         /* Try to prepend newex to the ex */
         if (ext4_can_extents_be_merged(inode, newext, ex)) {
             ext_debug(inode, "prepend %u[%d]%d block to %u:[%d]%d"
                   "(from %llu)\n",
                   le32_to_cpu(newext->ee_block),
                   ext4_ext_is_unwritten(newext),
                   ext4_ext_get_actual_len(newext),
                   le32_to_cpu(ex->ee_block),
                   ext4_ext_is_unwritten(ex),
                   ext4_ext_get_actual_len(ex),
                   ext4_ext_pblock(ex));
             err = ext4_ext_get_access(handle, inode,
                           path + depth);
             if (err)
                 return err;
 
             unwritten = ext4_ext_is_unwritten(ex);
             ex->ee_block = newext->ee_block;
             ext4_ext_store_pblock(ex, ext4_ext_pblock(newext));
             ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
                     + ext4_ext_get_actual_len(newext));
             if (unwritten)
                 ext4_ext_mark_unwritten(ex);
             nearex = ex;
             goto merge;
         }
     }
 
     depth = ext_depth(inode);
     eh = path[depth].p_hdr;
     if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
         goto has_space;
 
     /* probably next leaf has space for us? */
     fex = EXT_LAST_EXTENT(eh);
     next = EXT_MAX_BLOCKS;
     if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block))
         next = ext4_ext_next_leaf_block(path);
     if (next != EXT_MAX_BLOCKS) {
         ext_debug(inode, "next leaf block - %u\n", next);
         BUG_ON(npath != NULL);
         npath = ext4_find_extent(inode, next, NULL, gb_flags);
         if (IS_ERR(npath))
             return PTR_ERR(npath);
         BUG_ON(npath->p_depth != path->p_depth);
         eh = npath[depth].p_hdr;
         if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
             ext_debug(inode, "next leaf isn't full(%d)\n",
                   le16_to_cpu(eh->eh_entries));
             path = npath;
             goto has_space;
         }
         ext_debug(inode, "next leaf has no free space(%d,%d)\n",
               le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
     }
 
     /*
      * There is no free space in the found leaf.
      * We're gonna add a new leaf in the tree.
      */
     if (gb_flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
         mb_flags |= EXT4_MB_USE_RESERVED;
     err = ext4_ext_create_new_leaf(handle, inode, mb_flags, gb_flags,
                        ppath, newext);
     if (err)
         goto cleanup;
     depth = ext_depth(inode);
     eh = path[depth].p_hdr;
 
 has_space:
     nearex = path[depth].p_ext;
 
     err = ext4_ext_get_access(handle, inode, path + depth);
     if (err)
         goto cleanup;
 
     if (!nearex) {
         /* there is no extent in this leaf, create first one */
         ext_debug(inode, "first extent in the leaf: %u:%llu:[%d]%d\n",
                 le32_to_cpu(newext->ee_block),
                 ext4_ext_pblock(newext),
                 ext4_ext_is_unwritten(newext),
                 ext4_ext_get_actual_len(newext));
         nearex = EXT_FIRST_EXTENT(eh);
     } else {
         if (le32_to_cpu(newext->ee_block)
                > le32_to_cpu(nearex->ee_block)) {
             /* Insert after */
             ext_debug(inode, "insert %u:%llu:[%d]%d before: "
                     "nearest %p\n",
                     le32_to_cpu(newext->ee_block),
                     ext4_ext_pblock(newext),
                     ext4_ext_is_unwritten(newext),
                     ext4_ext_get_actual_len(newext),
                     nearex);
             nearex++;
         } else {
             /* Insert before */
             BUG_ON(newext->ee_block == nearex->ee_block);
             ext_debug(inode, "insert %u:%llu:[%d]%d after: "
                     "nearest %p\n",
                     le32_to_cpu(newext->ee_block),
                     ext4_ext_pblock(newext),
                     ext4_ext_is_unwritten(newext),
                     ext4_ext_get_actual_len(newext),
                     nearex);
         }
         len = EXT_LAST_EXTENT(eh) - nearex + 1;
         if (len > 0) {
             ext_debug(inode, "insert %u:%llu:[%d]%d: "
                     "move %d extents from 0x%p to 0x%p\n",
                     le32_to_cpu(newext->ee_block),
                     ext4_ext_pblock(newext),
                     ext4_ext_is_unwritten(newext),
                     ext4_ext_get_actual_len(newext),
                     len, nearex, nearex + 1);
             memmove(nearex + 1, nearex,
                 len * sizeof(struct ext4_extent));
         }
     }
 
     le16_add_cpu(&eh->eh_entries, 1);
     path[depth].p_ext = nearex;
     nearex->ee_block = newext->ee_block;
     ext4_ext_store_pblock(nearex, ext4_ext_pblock(newext));
     nearex->ee_len = newext->ee_len;
 
 merge:
     /* try to merge extents */
     if (!(gb_flags & EXT4_GET_BLOCKS_PRE_IO))
         ext4_ext_try_to_merge(handle, inode, path, nearex);
 
 
     /* time to correct all indexes above */
     err = ext4_ext_correct_indexes(handle, inode, path);
     if (err)
         goto cleanup;
 
     err = ext4_ext_dirty(handle, inode, path + path->p_depth);
 
 cleanup:
     ext4_ext_drop_refs(npath);
     kfree(npath);
     return err;
 }
 
 static int ext4_fill_es_cache_info(struct inode *inode,
                    ext4_lblk_t block, ext4_lblk_t num,
                    struct fiemap_extent_info *fieinfo)
 {
     ext4_lblk_t next, end = block + num - 1;
     struct extent_status es;
     unsigned char blksize_bits = inode->i_sb->s_blocksize_bits;
     unsigned int flags;
     int err;
 
     while (block <= end) {
         next = 0;
         flags = 0;
         if (!ext4_es_lookup_extent(inode, block, &next, &es))
             break;
         if (ext4_es_is_unwritten(&es))
             flags |= FIEMAP_EXTENT_UNWRITTEN;
         if (ext4_es_is_delayed(&es))
             flags |= (FIEMAP_EXTENT_DELALLOC |
                   FIEMAP_EXTENT_UNKNOWN);
         if (ext4_es_is_hole(&es))
             flags |= EXT4_FIEMAP_EXTENT_HOLE;
         if (next == 0)
             flags |= FIEMAP_EXTENT_LAST;
         if (flags & (FIEMAP_EXTENT_DELALLOC|
                  EXT4_FIEMAP_EXTENT_HOLE))
             es.es_pblk = 0;
         else
             es.es_pblk = ext4_es_pblock(&es);
         err = fiemap_fill_next_extent(fieinfo,
                 (__u64)es.es_lblk << blksize_bits,
                 (__u64)es.es_pblk << blksize_bits,
                 (__u64)es.es_len << blksize_bits,
                 flags);
         if (next == 0)
             break;
         block = next;
         if (err < 0)
             return err;
         if (err == 1)
             return 0;
     }
     return 0;
 }
 
 
 /*
  * ext4_ext_determine_hole - determine hole around given block
  * @inode:  inode we lookup in
  * @path:   path in extent tree to @lblk
  * @lblk:   pointer to logical block around which we want to determine hole
  *
  * Determine hole length (and start if easily possible) around given logical
  * block. We don't try too hard to find the beginning of the hole but @path
  * actually points to extent before @lblk, we provide it.
  *
  * The function returns the length of a hole starting at @lblk. We update @lblk
  * to the beginning of the hole if we managed to find it.
  */
 static ext4_lblk_t ext4_ext_determine_hole(struct inode *inode,
                        struct ext4_ext_path *path,
                        ext4_lblk_t *lblk)
 {
     int depth = ext_depth(inode);
     struct ext4_extent *ex;
     ext4_lblk_t len;
 
     ex = path[depth].p_ext;
     if (ex == NULL) {
         /* there is no extent yet, so gap is [0;-] */
         *lblk = 0;
         len = EXT_MAX_BLOCKS;
     } else if (*lblk < le32_to_cpu(ex->ee_block)) {
         len = le32_to_cpu(ex->ee_block) - *lblk;
     } else if (*lblk >= le32_to_cpu(ex->ee_block)
             + ext4_ext_get_actual_len(ex)) {
         ext4_lblk_t next;
 
         *lblk = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
         next = ext4_ext_next_allocated_block(path);
         BUG_ON(next == *lblk);
         len = next - *lblk;
     } else {
         BUG();
     }
     return len;
 }
 
 /*
  * ext4_ext_put_gap_in_cache:
  * calculate boundaries of the gap that the requested block fits into
  * and cache this gap
  */
 static void
 ext4_ext_put_gap_in_cache(struct inode *inode, ext4_lblk_t hole_start,
               ext4_lblk_t hole_len)
 {
     struct extent_status es;
 
     ext4_es_find_extent_range(inode, &ext4_es_is_delayed, hole_start,
                   hole_start + hole_len - 1, &es);
     if (es.es_len) {
         /* There's delayed extent containing lblock? */
         if (es.es_lblk <= hole_start)
             return;
         hole_len = min(es.es_lblk - hole_start, hole_len);
     }
     ext_debug(inode, " -> %u:%u\n", hole_start, hole_len);
     ext4_es_insert_extent(inode, hole_start, hole_len, ~0,
                   EXTENT_STATUS_HOLE);
 }
 
 /*
  * ext4_ext_rm_idx:
  * removes index from the index block.
  */
 static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
             struct ext4_ext_path *path, int depth)
 {
     int err;
     ext4_fsblk_t leaf;
 
     /* free index block */
     depth--;
     path = path + depth;
     leaf = ext4_idx_pblock(path->p_idx);
     if (unlikely(path->p_hdr->eh_entries == 0)) {
         EXT4_ERROR_INODE(inode, "path->p_hdr->eh_entries == 0");
         return -EFSCORRUPTED;
     }
     err = ext4_ext_get_access(handle, inode, path);
     if (err)
         return err;
 
     if (path->p_idx != EXT_LAST_INDEX(path->p_hdr)) {
         int len = EXT_LAST_INDEX(path->p_hdr) - path->p_idx;
         len *= sizeof(struct ext4_extent_idx);
         memmove(path->p_idx, path->p_idx + 1, len);
     }
 
     le16_add_cpu(&path->p_hdr->eh_entries, -1);
     err = ext4_ext_dirty(handle, inode, path);
     if (err)
         return err;
     ext_debug(inode, "index is empty, remove it, free block %llu\n", leaf);
     trace_ext4_ext_rm_idx(inode, leaf);
 
     ext4_free_blocks(handle, inode, NULL, leaf, 1,
              EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
 
     while (--depth >= 0) {
         if (path->p_idx != EXT_FIRST_INDEX(path->p_hdr))
             break;
         path--;
         err = ext4_ext_get_access(handle, inode, path);
         if (err)
             break;
         path->p_idx->ei_block = (path+1)->p_idx->ei_block;
         err = ext4_ext_dirty(handle, inode, path);
         if (err)
             break;
     }
     return err;
 }
 
 /*
  * ext4_ext_calc_credits_for_single_extent:
  * This routine returns max. credits that needed to insert an extent
  * to the extent tree.
  * When pass the actual path, the caller should calculate credits
  * under i_data_sem.
  */
 int ext4_ext_calc_credits_for_single_extent(struct inode *inode, int nrblocks,
                         struct ext4_ext_path *path)
 {
     if (path) {
         int depth = ext_depth(inode);
         int ret = 0;
 
         /* probably there is space in leaf? */
         if (le16_to_cpu(path[depth].p_hdr->eh_entries)
                 < le16_to_cpu(path[depth].p_hdr->eh_max)) {
 
             /*
              *  There are some space in the leaf tree, no
              *  need to account for leaf block credit
              *
              *  bitmaps and block group descriptor blocks
              *  and other metadata blocks still need to be
              *  accounted.
              */
             /* 1 bitmap, 1 block group descriptor */
             ret = 2 + EXT4_META_TRANS_BLOCKS(inode->i_sb);
             return ret;
         }
     }
 
     return ext4_chunk_trans_blocks(inode, nrblocks);
 }
 
 /*
  * How many index/leaf blocks need to change/allocate to add @extents extents?
  *
  * If we add a single extent, then in the worse case, each tree level
  * index/leaf need to be changed in case of the tree split.
  *
  * If more extents are inserted, they could cause the whole tree split more
  * than once, but this is really rare.
  */
 int ext4_ext_index_trans_blocks(struct inode *inode, int extents)
 {
     int index;
     int depth;
 
     /* If we are converting the inline data, only one is needed here. */
     if (ext4_has_inline_data(inode))
         return 1;
 
     depth = ext_depth(inode);
 
     if (extents <= 1)
         index = depth * 2;
     else
         index = depth * 3;
 
     return index;
 }
 
 static inline int get_default_free_blocks_flags(struct inode *inode)
 {
     if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
         ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE))
         return EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET;
     else if (ext4_should_journal_data(inode))
         return EXT4_FREE_BLOCKS_FORGET;
     return 0;
 }
 
 /*
  * ext4_rereserve_cluster - increment the reserved cluster count when
  *                          freeing a cluster with a pending reservation
  *
  * @inode - file containing the cluster
  * @lblk - logical block in cluster to be reserved
  *
  * Increments the reserved cluster count and adjusts quota in a bigalloc
  * file system when freeing a partial cluster containing at least one
  * delayed and unwritten block.  A partial cluster meeting that
  * requirement will have a pending reservation.  If so, the
  * RERESERVE_CLUSTER flag is used when calling ext4_free_blocks() to
  * defer reserved and allocated space accounting to a subsequent call
  * to this function.
  */
 static void ext4_rereserve_cluster(struct inode *inode, ext4_lblk_t lblk)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     struct ext4_inode_info *ei = EXT4_I(inode);
 
     dquot_reclaim_block(inode, EXT4_C2B(sbi, 1));
 
     spin_lock(&ei->i_block_reservation_lock);
     ei->i_reserved_data_blocks++;
     percpu_counter_add(&sbi->s_dirtyclusters_counter, 1);
     spin_unlock(&ei->i_block_reservation_lock);
 
     percpu_counter_add(&sbi->s_freeclusters_counter, 1);
     ext4_remove_pending(inode, lblk);
 }
 
 static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
                   struct ext4_extent *ex,
                   struct partial_cluster *partial,
                   ext4_lblk_t from, ext4_lblk_t to)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     unsigned short ee_len = ext4_ext_get_actual_len(ex);
     ext4_fsblk_t last_pblk, pblk;
     ext4_lblk_t num;
     int flags;
 
     /* only extent tail removal is allowed */
     if (from < le32_to_cpu(ex->ee_block) ||
         to != le32_to_cpu(ex->ee_block) + ee_len - 1) {
         ext4_error(sbi->s_sb,
                "strange request: removal(2) %u-%u from %u:%u",
                from, to, le32_to_cpu(ex->ee_block), ee_len);
         return 0;
     }
 
 #ifdef EXTENTS_STATS
     spin_lock(&sbi->s_ext_stats_lock);
     sbi->s_ext_blocks += ee_len;
     sbi->s_ext_extents++;
     if (ee_len < sbi->s_ext_min)
         sbi->s_ext_min = ee_len;
     if (ee_len > sbi->s_ext_max)
         sbi->s_ext_max = ee_len;
     if (ext_depth(inode) > sbi->s_depth_max)
         sbi->s_depth_max = ext_depth(inode);
     spin_unlock(&sbi->s_ext_stats_lock);
 #endif
 
     trace_ext4_remove_blocks(inode, ex, from, to, partial);
 
     /*
      * if we have a partial cluster, and it's different from the
      * cluster of the last block in the extent, we free it
      */
     last_pblk = ext4_ext_pblock(ex) + ee_len - 1;
 
     if (partial->state != initial &&
         partial->pclu != EXT4_B2C(sbi, last_pblk)) {
         if (partial->state == tofree) {
             flags = get_default_free_blocks_flags(inode);
             if (ext4_is_pending(inode, partial->lblk))
                 flags |= EXT4_FREE_BLOCKS_RERESERVE_CLUSTER;
             ext4_free_blocks(handle, inode, NULL,
                      EXT4_C2B(sbi, partial->pclu),
                      sbi->s_cluster_ratio, flags);
             if (flags & EXT4_FREE_BLOCKS_RERESERVE_CLUSTER)
                 ext4_rereserve_cluster(inode, partial->lblk);
         }
         partial->state = initial;
     }
 
     num = le32_to_cpu(ex->ee_block) + ee_len - from;
     pblk = ext4_ext_pblock(ex) + ee_len - num;
 
     /*
      * We free the partial cluster at the end of the extent (if any),
      * unless the cluster is used by another extent (partial_cluster
      * state is nofree).  If a partial cluster exists here, it must be
      * shared with the last block in the extent.
      */
     flags = get_default_free_blocks_flags(inode);
 
     /* partial, left end cluster aligned, right end unaligned */
     if ((EXT4_LBLK_COFF(sbi, to) != sbi->s_cluster_ratio - 1) &&
         (EXT4_LBLK_CMASK(sbi, to) >= from) &&
         (partial->state != nofree)) {
         if (ext4_is_pending(inode, to))
             flags |= EXT4_FREE_BLOCKS_RERESERVE_CLUSTER;
         ext4_free_blocks(handle, inode, NULL,
                  EXT4_PBLK_CMASK(sbi, last_pblk),
                  sbi->s_cluster_ratio, flags);
         if (flags & EXT4_FREE_BLOCKS_RERESERVE_CLUSTER)
             ext4_rereserve_cluster(inode, to);
         partial->state = initial;
         flags = get_default_free_blocks_flags(inode);
     }
 
     flags |= EXT4_FREE_BLOCKS_NOFREE_LAST_CLUSTER;
 
     /*
      * For bigalloc file systems, we never free a partial cluster
      * at the beginning of the extent.  Instead, we check to see if we
      * need to free it on a subsequent call to ext4_remove_blocks,
      * or at the end of ext4_ext_rm_leaf or ext4_ext_remove_space.
      */
     flags |= EXT4_FREE_BLOCKS_NOFREE_FIRST_CLUSTER;
     ext4_free_blocks(handle, inode, NULL, pblk, num, flags);
 
     /* reset the partial cluster if we've freed past it */
     if (partial->state != initial && partial->pclu != EXT4_B2C(sbi, pblk))
         partial->state = initial;
 
     /*
      * If we've freed the entire extent but the beginning is not left
      * cluster aligned and is not marked as ineligible for freeing we
      * record the partial cluster at the beginning of the extent.  It
      * wasn't freed by the preceding ext4_free_blocks() call, and we
      * need to look farther to the left to determine if it's to be freed
      * (not shared with another extent). Else, reset the partial
      * cluster - we're either  done freeing or the beginning of the
      * extent is left cluster aligned.
      */
     if (EXT4_LBLK_COFF(sbi, from) && num == ee_len) {
         if (partial->state == initial) {
             partial->pclu = EXT4_B2C(sbi, pblk);
             partial->lblk = from;
             partial->state = tofree;
         }
     } else {
         partial->state = initial;
     }
 
     return 0;
 }
 
 /*
  * ext4_ext_rm_leaf() Removes the extents associated with the
  * blocks appearing between "start" and "end".  Both "start"
  * and "end" must appear in the same extent or EIO is returned.
  *
  * @handle: The journal handle
  * @inode:  The files inode
  * @path:   The path to the leaf
  * @partial_cluster: The cluster which we'll have to free if all extents
  *                   has been released from it.  However, if this value is
  *                   negative, it's a cluster just to the right of the
  *                   punched region and it must not be freed.
  * @start:  The first block to remove
  * @end:   The last block to remove
  */
 static int
 ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
          struct ext4_ext_path *path,
          struct partial_cluster *partial,
          ext4_lblk_t start, ext4_lblk_t end)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     int err = 0, correct_index = 0;
     int depth = ext_depth(inode), credits, revoke_credits;
     struct ext4_extent_header *eh;
     ext4_lblk_t a, b;
     unsigned num;
     ext4_lblk_t ex_ee_block;
     unsigned short ex_ee_len;
     unsigned unwritten = 0;
     struct ext4_extent *ex;
     ext4_fsblk_t pblk;
 
     /* the header must be checked already in ext4_ext_remove_space() */
     ext_debug(inode, "truncate since %u in leaf to %u\n", start, end);
     if (!path[depth].p_hdr)
         path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
     eh = path[depth].p_hdr;
     if (unlikely(path[depth].p_hdr == NULL)) {
         EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
         return -EFSCORRUPTED;
     }
     /* find where to start removing */
     ex = path[depth].p_ext;
     if (!ex)
         ex = EXT_LAST_EXTENT(eh);
 
     ex_ee_block = le32_to_cpu(ex->ee_block);
     ex_ee_len = ext4_ext_get_actual_len(ex);
 
     trace_ext4_ext_rm_leaf(inode, start, ex, partial);
 
     while (ex >= EXT_FIRST_EXTENT(eh) &&
             ex_ee_block + ex_ee_len > start) {
 
         if (ext4_ext_is_unwritten(ex))
             unwritten = 1;
         else
             unwritten = 0;
 
         ext_debug(inode, "remove ext %u:[%d]%d\n", ex_ee_block,
               unwritten, ex_ee_len);
         path[depth].p_ext = ex;
 
         a = ex_ee_block > start ? ex_ee_block : start;
         b = ex_ee_block+ex_ee_len - 1 < end ?
             ex_ee_block+ex_ee_len - 1 : end;
 
         ext_debug(inode, "  border %u:%u\n", a, b);
 
         /* If this extent is beyond the end of the hole, skip it */
         if (end < ex_ee_block) {
             /*
              * We're going to skip this extent and move to another,
              * so note that its first cluster is in use to avoid
              * freeing it when removing blocks.  Eventually, the
              * right edge of the truncated/punched region will
              * be just to the left.
              */
             if (sbi->s_cluster_ratio > 1) {
                 pblk = ext4_ext_pblock(ex);
                 partial->pclu = EXT4_B2C(sbi, pblk);
                 partial->state = nofree;
             }
             ex--;
             ex_ee_block = le32_to_cpu(ex->ee_block);
             ex_ee_len = ext4_ext_get_actual_len(ex);
             continue;
         } else if (b != ex_ee_block + ex_ee_len - 1) {
             EXT4_ERROR_INODE(inode,
                      "can not handle truncate %u:%u "
                      "on extent %u:%u",
                      start, end, ex_ee_block,
                      ex_ee_block + ex_ee_len - 1);
             err = -EFSCORRUPTED;
             goto out;
         } else if (a != ex_ee_block) {
             /* remove tail of the extent */
             num = a - ex_ee_block;
         } else {
             /* remove whole extent: excellent! */
             num = 0;
         }
         /*
          * 3 for leaf, sb, and inode plus 2 (bmap and group
          * descriptor) for each block group; assume two block
          * groups plus ex_ee_len/blocks_per_block_group for
          * the worst case
          */
         credits = 7 + 2*(ex_ee_len/EXT4_BLOCKS_PER_GROUP(inode->i_sb));
         if (ex == EXT_FIRST_EXTENT(eh)) {
             correct_index = 1;
             credits += (ext_depth(inode)) + 1;
         }
         credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
         /*
          * We may end up freeing some index blocks and data from the
          * punched range. Note that partial clusters are accounted for
          * by ext4_free_data_revoke_credits().
          */
         revoke_credits =
             ext4_free_metadata_revoke_credits(inode->i_sb,
                               ext_depth(inode)) +
             ext4_free_data_revoke_credits(inode, b - a + 1);
 
         err = ext4_datasem_ensure_credits(handle, inode, credits,
                           credits, revoke_credits);
         if (err) {
             if (err > 0)
                 err = -EAGAIN;
             goto out;
         }
 
         err = ext4_ext_get_access(handle, inode, path + depth);
         if (err)
             goto out;
 
         err = ext4_remove_blocks(handle, inode, ex, partial, a, b);
         if (err)
             goto out;
 
         if (num == 0)
             /* this extent is removed; mark slot entirely unused */
             ext4_ext_store_pblock(ex, 0);
 
         ex->ee_len = cpu_to_le16(num);
         /*
          * Do not mark unwritten if all the blocks in the
          * extent have been removed.
          */
         if (unwritten && num)
             ext4_ext_mark_unwritten(ex);
         /*
          * If the extent was completely released,
          * we need to remove it from the leaf
          */
         if (num == 0) {
             if (end != EXT_MAX_BLOCKS - 1) {
                 /*
                  * For hole punching, we need to scoot all the
                  * extents up when an extent is removed so that
                  * we dont have blank extents in the middle
                  */
                 memmove(ex, ex+1, (EXT_LAST_EXTENT(eh) - ex) *
                     sizeof(struct ext4_extent));
 
                 /* Now get rid of the one at the end */
                 memset(EXT_LAST_EXTENT(eh), 0,
                     sizeof(struct ext4_extent));
             }
             le16_add_cpu(&eh->eh_entries, -1);
         }
 
         err = ext4_ext_dirty(handle, inode, path + depth);
         if (err)
             goto out;
 
         ext_debug(inode, "new extent: %u:%u:%llu\n", ex_ee_block, num,
                 ext4_ext_pblock(ex));
         ex--;
         ex_ee_block = le32_to_cpu(ex->ee_block);
         ex_ee_len = ext4_ext_get_actual_len(ex);
     }
 
     if (correct_index && eh->eh_entries)
         err = ext4_ext_correct_indexes(handle, inode, path);
 
     /*
      * If there's a partial cluster and at least one extent remains in
      * the leaf, free the partial cluster if it isn't shared with the
      * current extent.  If it is shared with the current extent
      * we reset the partial cluster because we've reached the start of the
      * truncated/punched region and we're done removing blocks.
      */
     if (partial->state == tofree && ex >= EXT_FIRST_EXTENT(eh)) {
         pblk = ext4_ext_pblock(ex) + ex_ee_len - 1;
         if (partial->pclu != EXT4_B2C(sbi, pblk)) {
             int flags = get_default_free_blocks_flags(inode);
 
             if (ext4_is_pending(inode, partial->lblk))
                 flags |= EXT4_FREE_BLOCKS_RERESERVE_CLUSTER;
             ext4_free_blocks(handle, inode, NULL,
                      EXT4_C2B(sbi, partial->pclu),
                      sbi->s_cluster_ratio, flags);
             if (flags & EXT4_FREE_BLOCKS_RERESERVE_CLUSTER)
                 ext4_rereserve_cluster(inode, partial->lblk);
         }
         partial->state = initial;
     }
 
     /* if this leaf is free, then we should
      * remove it from index block above */
     if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
         err = ext4_ext_rm_idx(handle, inode, path, depth);
 
 out:
     return err;
 }
 
 /*
  * ext4_ext_more_to_rm:
  * returns 1 if current index has to be freed (even partial)
  */
 static int
 ext4_ext_more_to_rm(struct ext4_ext_path *path)
 {
     BUG_ON(path->p_idx == NULL);
 
     if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
         return 0;
 
     /*
      * if truncate on deeper level happened, it wasn't partial,
      * so we have to consider current index for truncation
      */
     if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
         return 0;
     return 1;
 }
 
 int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
               ext4_lblk_t end)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     int depth = ext_depth(inode);
     struct ext4_ext_path *path = NULL;
     struct partial_cluster partial;
     handle_t *handle;
     int i = 0, err = 0;
 
     partial.pclu = 0;
     partial.lblk = 0;
     partial.state = initial;
 
     ext_debug(inode, "truncate since %u to %u\n", start, end);
 
     /* probably first extent we're gonna free will be last in block */
     handle = ext4_journal_start_with_revoke(inode, EXT4_HT_TRUNCATE,
             depth + 1,
             ext4_free_metadata_revoke_credits(inode->i_sb, depth));
     if (IS_ERR(handle))
         return PTR_ERR(handle);
 
 again:
     trace_ext4_ext_remove_space(inode, start, end, depth);
 
     /*
      * Check if we are removing extents inside the extent tree. If that
      * is the case, we are going to punch a hole inside the extent tree
      * so we have to check whether we need to split the extent covering
      * the last block to remove so we can easily remove the part of it
      * in ext4_ext_rm_leaf().
      */
     if (end < EXT_MAX_BLOCKS - 1) {
         struct ext4_extent *ex;
         ext4_lblk_t ee_block, ex_end, lblk;
         ext4_fsblk_t pblk;
 
         /* find extent for or closest extent to this block */
         path = ext4_find_extent(inode, end, NULL,
                     EXT4_EX_NOCACHE | EXT4_EX_NOFAIL);
         if (IS_ERR(path)) {
             ext4_journal_stop(handle);
             return PTR_ERR(path);
         }
         depth = ext_depth(inode);
         /* Leaf not may not exist only if inode has no blocks at all */
         ex = path[depth].p_ext;
         if (!ex) {
             if (depth) {
                 EXT4_ERROR_INODE(inode,
                          "path[%d].p_hdr == NULL",
                          depth);
                 err = -EFSCORRUPTED;
             }
             goto out;
         }
 
         ee_block = le32_to_cpu(ex->ee_block);
         ex_end = ee_block + ext4_ext_get_actual_len(ex) - 1;
 
         /*
          * See if the last block is inside the extent, if so split
          * the extent at 'end' block so we can easily remove the
          * tail of the first part of the split extent in
          * ext4_ext_rm_leaf().
          */
         if (end >= ee_block && end < ex_end) {
 
             /*
              * If we're going to split the extent, note that
              * the cluster containing the block after 'end' is
              * in use to avoid freeing it when removing blocks.
              */
             if (sbi->s_cluster_ratio > 1) {
                 pblk = ext4_ext_pblock(ex) + end - ee_block + 1;
                 partial.pclu = EXT4_B2C(sbi, pblk);
                 partial.state = nofree;
             }
 
             /*
              * Split the extent in two so that 'end' is the last
              * block in the first new extent. Also we should not
              * fail removing space due to ENOSPC so try to use
              * reserved block if that happens.
              */
             err = ext4_force_split_extent_at(handle, inode, &path,
                              end + 1, 1);
             if (err < 0)
                 goto out;
 
         } else if (sbi->s_cluster_ratio > 1 && end >= ex_end &&
                partial.state == initial) {
             /*
              * If we're punching, there's an extent to the right.
              * If the partial cluster hasn't been set, set it to
              * that extent's first cluster and its state to nofree
              * so it won't be freed should it contain blocks to be
              * removed. If it's already set (tofree/nofree), we're
              * retrying and keep the original partial cluster info
              * so a cluster marked tofree as a result of earlier
              * extent removal is not lost.
              */
             lblk = ex_end + 1;
             err = ext4_ext_search_right(inode, path, &lblk, &pblk,
                             NULL);
             if (err < 0)
                 goto out;
             if (pblk) {
                 partial.pclu = EXT4_B2C(sbi, pblk);
                 partial.state = nofree;
             }
         }
     }
     /*
      * We start scanning from right side, freeing all the blocks
      * after i_size and walking into the tree depth-wise.
      */
     depth = ext_depth(inode);
     if (path) {
         int k = i = depth;
         while (--k > 0)
             path[k].p_block =
                 le16_to_cpu(path[k].p_hdr->eh_entries)+1;
     } else {
         path = kcalloc(depth + 1, sizeof(struct ext4_ext_path),
                    GFP_NOFS | __GFP_NOFAIL);
         if (path == NULL) {
             ext4_journal_stop(handle);
             return -ENOMEM;
         }
         path[0].p_maxdepth = path[0].p_depth = depth;
         path[0].p_hdr = ext_inode_hdr(inode);
         i = 0;
 
         if (ext4_ext_check(inode, path[0].p_hdr, depth, 0)) {
             err = -EFSCORRUPTED;
             goto out;
         }
     }
     err = 0;
 
     while (i >= 0 && err == 0) {
         if (i == depth) {
             /* this is leaf block */
             err = ext4_ext_rm_leaf(handle, inode, path,
                            &partial, start, end);
             /* root level has p_bh == NULL, brelse() eats this */
             brelse(path[i].p_bh);
             path[i].p_bh = NULL;
             i--;
             continue;
         }
 
         /* this is index block */
         if (!path[i].p_hdr) {
             ext_debug(inode, "initialize header\n");
             path[i].p_hdr = ext_block_hdr(path[i].p_bh);
         }
 
         if (!path[i].p_idx) {
             /* this level hasn't been touched yet */
             path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
             path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
             ext_debug(inode, "init index ptr: hdr 0x%p, num %d\n",
                   path[i].p_hdr,
                   le16_to_cpu(path[i].p_hdr->eh_entries));
         } else {
             /* we were already here, see at next index */
             path[i].p_idx--;
         }
 
         ext_debug(inode, "level %d - index, first 0x%p, cur 0x%p\n",
                 i, EXT_FIRST_INDEX(path[i].p_hdr),
                 path[i].p_idx);
         if (ext4_ext_more_to_rm(path + i)) {
             struct buffer_head *bh;
             /* go to the next level */
             ext_debug(inode, "move to level %d (block %llu)\n",
                   i + 1, ext4_idx_pblock(path[i].p_idx));
             memset(path + i + 1, 0, sizeof(*path));
             bh = read_extent_tree_block(inode, path[i].p_idx,
                             depth - i - 1,
                             EXT4_EX_NOCACHE);
             if (IS_ERR(bh)) {
                 /* should we reset i_size? */
                 err = PTR_ERR(bh);
                 break;
             }
             /* Yield here to deal with large extent trees.
              * Should be a no-op if we did IO above. */
             cond_resched();
             if (WARN_ON(i + 1 > depth)) {
                 err = -EFSCORRUPTED;
                 break;
             }
             path[i + 1].p_bh = bh;
 
             /* save actual number of indexes since this
              * number is changed at the next iteration */
             path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
             i++;
         } else {
             /* we finished processing this index, go up */
             if (path[i].p_hdr->eh_entries == 0 && i > 0) {
                 /* index is empty, remove it;
                  * handle must be already prepared by the
                  * truncatei_leaf() */
                 err = ext4_ext_rm_idx(handle, inode, path, i);
             }
             /* root level has p_bh == NULL, brelse() eats this */
             brelse(path[i].p_bh);
             path[i].p_bh = NULL;
             i--;
             ext_debug(inode, "return to level %d\n", i);
         }
     }
 
     trace_ext4_ext_remove_space_done(inode, start, end, depth, &partial,
                      path->p_hdr->eh_entries);
 
     /*
      * if there's a partial cluster and we have removed the first extent
      * in the file, then we also free the partial cluster, if any
      */
     if (partial.state == tofree && err == 0) {
         int flags = get_default_free_blocks_flags(inode);
 
         if (ext4_is_pending(inode, partial.lblk))
             flags |= EXT4_FREE_BLOCKS_RERESERVE_CLUSTER;
         ext4_free_blocks(handle, inode, NULL,
                  EXT4_C2B(sbi, partial.pclu),
                  sbi->s_cluster_ratio, flags);
         if (flags & EXT4_FREE_BLOCKS_RERESERVE_CLUSTER)
             ext4_rereserve_cluster(inode, partial.lblk);
         partial.state = initial;
     }
 
     /* TODO: flexible tree reduction should be here */
     if (path->p_hdr->eh_entries == 0) {
         /*
          * truncate to zero freed all the tree,
          * so we need to correct eh_depth
          */
         err = ext4_ext_get_access(handle, inode, path);
         if (err == 0) {
             ext_inode_hdr(inode)->eh_depth = 0;
             ext_inode_hdr(inode)->eh_max =
                 cpu_to_le16(ext4_ext_space_root(inode, 0));
             err = ext4_ext_dirty(handle, inode, path);
         }
     }
 out:
     ext4_ext_drop_refs(path);
     kfree(path);
     path = NULL;
     if (err == -EAGAIN)
         goto again;
     ext4_journal_stop(handle);
 
     return err;
 }
 
 /*
  * called at mount time
  */
 void ext4_ext_init(struct super_block *sb)
 {
     /*
      * possible initialization would be here
      */
 
     if (ext4_has_feature_extents(sb)) {
 #if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
         printk(KERN_INFO "EXT4-fs: file extents enabled"
 #ifdef AGGRESSIVE_TEST
                ", aggressive tests"
 #endif
 #ifdef CHECK_BINSEARCH
                ", check binsearch"
 #endif
 #ifdef EXTENTS_STATS
                ", stats"
 #endif
                "\n");
 #endif
 #ifdef EXTENTS_STATS
         spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
         EXT4_SB(sb)->s_ext_min = 1 << 30;
         EXT4_SB(sb)->s_ext_max = 0;
 #endif
     }
 }
 
 /*
  * called at umount time
  */
 void ext4_ext_release(struct super_block *sb)
 {
     if (!ext4_has_feature_extents(sb))
         return;
 
 #ifdef EXTENTS_STATS
     if (EXT4_SB(sb)->s_ext_blocks && EXT4_SB(sb)->s_ext_extents) {
         struct ext4_sb_info *sbi = EXT4_SB(sb);
         printk(KERN_ERR "EXT4-fs: %lu blocks in %lu extents (%lu ave)\n",
             sbi->s_ext_blocks, sbi->s_ext_extents,
             sbi->s_ext_blocks / sbi->s_ext_extents);
         printk(KERN_ERR "EXT4-fs: extents: %lu min, %lu max, max depth %lu\n",
             sbi->s_ext_min, sbi->s_ext_max, sbi->s_depth_max);
     }
 #endif
 }
 
 static int ext4_zeroout_es(struct inode *inode, struct ext4_extent *ex)
 {
     ext4_lblk_t  ee_block;
     ext4_fsblk_t ee_pblock;
     unsigned int ee_len;
 
     ee_block  = le32_to_cpu(ex->ee_block);
     ee_len    = ext4_ext_get_actual_len(ex);
     ee_pblock = ext4_ext_pblock(ex);
 
     if (ee_len == 0)
         return 0;
 
     return ext4_es_insert_extent(inode, ee_block, ee_len, ee_pblock,
                      EXTENT_STATUS_WRITTEN);
 }
 
 /* FIXME!! we need to try to merge to left or right after zero-out  */
 static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
 {
     ext4_fsblk_t ee_pblock;
     unsigned int ee_len;
 
     ee_len    = ext4_ext_get_actual_len(ex);
     ee_pblock = ext4_ext_pblock(ex);
     return ext4_issue_zeroout(inode, le32_to_cpu(ex->ee_block), ee_pblock,
                   ee_len);
 }
 
 /*
  * ext4_split_extent_at() splits an extent at given block.
  *
  * @handle: the journal handle
  * @inode: the file inode
  * @path: the path to the extent
  * @split: the logical block where the extent is splitted.
  * @split_flags: indicates if the extent could be zeroout if split fails, and
  *       the states(init or unwritten) of new extents.
  * @flags: flags used to insert new extent to extent tree.
  *
  *
  * Splits extent [a, b] into two extents [a, @split) and [@split, b], states
  * of which are determined by split_flag.
  *
  * There are two cases:
  *  a> the extent are splitted into two extent.
  *  b> split is not needed, and just mark the extent.
  *
  * return 0 on success.
  */
 static int ext4_split_extent_at(handle_t *handle,
                  struct inode *inode,
                  struct ext4_ext_path **ppath,
                  ext4_lblk_t split,
                  int split_flag,
                  int flags)
 {
     struct ext4_ext_path *path = *ppath;
     ext4_fsblk_t newblock;
     ext4_lblk_t ee_block;
     struct ext4_extent *ex, newex, orig_ex, zero_ex;
     struct ext4_extent *ex2 = NULL;
     unsigned int ee_len, depth;
     int err = 0;
 
     BUG_ON((split_flag & (EXT4_EXT_DATA_VALID1 | EXT4_EXT_DATA_VALID2)) ==
            (EXT4_EXT_DATA_VALID1 | EXT4_EXT_DATA_VALID2));
 
     ext_debug(inode, "logical block %llu\n", (unsigned long long)split);
 
     ext4_ext_show_leaf(inode, path);
 
     depth = ext_depth(inode);
     ex = path[depth].p_ext;
     ee_block = le32_to_cpu(ex->ee_block);
     ee_len = ext4_ext_get_actual_len(ex);
     newblock = split - ee_block + ext4_ext_pblock(ex);
 
     BUG_ON(split < ee_block || split >= (ee_block + ee_len));
     BUG_ON(!ext4_ext_is_unwritten(ex) &&
            split_flag & (EXT4_EXT_MAY_ZEROOUT |
                  EXT4_EXT_MARK_UNWRIT1 |
                  EXT4_EXT_MARK_UNWRIT2));
 
     err = ext4_ext_get_access(handle, inode, path + depth);
     if (err)
         goto out;
 
     if (split == ee_block) {
         /*
          * case b: block @split is the block that the extent begins with
          * then we just change the state of the extent, and splitting
          * is not needed.
          */
         if (split_flag & EXT4_EXT_MARK_UNWRIT2)
             ext4_ext_mark_unwritten(ex);
         else
             ext4_ext_mark_initialized(ex);
 
         if (!(flags & EXT4_GET_BLOCKS_PRE_IO))
             ext4_ext_try_to_merge(handle, inode, path, ex);
 
         err = ext4_ext_dirty(handle, inode, path + path->p_depth);
         goto out;
     }
 
     /* case a */
     memcpy(&orig_ex, ex, sizeof(orig_ex));
     ex->ee_len = cpu_to_le16(split - ee_block);
     if (split_flag & EXT4_EXT_MARK_UNWRIT1)
         ext4_ext_mark_unwritten(ex);
 
     /*
      * path may lead to new leaf, not to original leaf any more
      * after ext4_ext_insert_extent() returns,
      */
     err = ext4_ext_dirty(handle, inode, path + depth);
     if (err)
         goto fix_extent_len;
 
     ex2 = &newex;
     ex2->ee_block = cpu_to_le32(split);
     ex2->ee_len   = cpu_to_le16(ee_len - (split - ee_block));
     ext4_ext_store_pblock(ex2, newblock);
     if (split_flag & EXT4_EXT_MARK_UNWRIT2)
         ext4_ext_mark_unwritten(ex2);
 
     err = ext4_ext_insert_extent(handle, inode, ppath, &newex, flags);
     if (err != -ENOSPC && err != -EDQUOT)
         goto out;
 
     if (EXT4_EXT_MAY_ZEROOUT & split_flag) {
         if (split_flag & (EXT4_EXT_DATA_VALID1|EXT4_EXT_DATA_VALID2)) {
             if (split_flag & EXT4_EXT_DATA_VALID1) {
                 err = ext4_ext_zeroout(inode, ex2);
                 zero_ex.ee_block = ex2->ee_block;
                 zero_ex.ee_len = cpu_to_le16(
                         ext4_ext_get_actual_len(ex2));
                 ext4_ext_store_pblock(&zero_ex,
                               ext4_ext_pblock(ex2));
             } else {
                 err = ext4_ext_zeroout(inode, ex);
                 zero_ex.ee_block = ex->ee_block;
                 zero_ex.ee_len = cpu_to_le16(
                         ext4_ext_get_actual_len(ex));
                 ext4_ext_store_pblock(&zero_ex,
                               ext4_ext_pblock(ex));
             }
         } else {
             err = ext4_ext_zeroout(inode, &orig_ex);
             zero_ex.ee_block = orig_ex.ee_block;
             zero_ex.ee_len = cpu_to_le16(
                         ext4_ext_get_actual_len(&orig_ex));
             ext4_ext_store_pblock(&zero_ex,
                           ext4_ext_pblock(&orig_ex));
         }
 
         if (!err) {
             /* update the extent length and mark as initialized */
             ex->ee_len = cpu_to_le16(ee_len);
             ext4_ext_try_to_merge(handle, inode, path, ex);
             err = ext4_ext_dirty(handle, inode, path + path->p_depth);
             if (!err)
                 /* update extent status tree */
                 err = ext4_zeroout_es(inode, &zero_ex);
             /* If we failed at this point, we don't know in which
              * state the extent tree exactly is so don't try to fix
              * length of the original extent as it may do even more
              * damage.
              */
             goto out;
         }
     }
 
 fix_extent_len:
     ex->ee_len = orig_ex.ee_len;
     /*
      * Ignore ext4_ext_dirty return value since we are already in error path
      * and err is a non-zero error code.
      */
     ext4_ext_dirty(handle, inode, path + path->p_depth);
     return err;
 out:
     ext4_ext_show_leaf(inode, path);
     return err;
 }
 
 /*
  * ext4_split_extents() splits an extent and mark extent which is covered
  * by @map as split_flags indicates
  *
  * It may result in splitting the extent into multiple extents (up to three)
  * There are three possibilities:
  *   a> There is no split required
  *   b> Splits in two extents: Split is happening at either end of the extent
  *   c> Splits in three extents: Somone is splitting in middle of the extent
  *
  */
 static int ext4_split_extent(handle_t *handle,
                   struct inode *inode,
                   struct ext4_ext_path **ppath,
                   struct ext4_map_blocks *map,
                   int split_flag,
                   int flags)
 {
     struct ext4_ext_path *path = *ppath;
     ext4_lblk_t ee_block;
     struct ext4_extent *ex;
     unsigned int ee_len, depth;
     int err = 0;
     int unwritten;
     int split_flag1, flags1;
     int allocated = map->m_len;
 
     depth = ext_depth(inode);
     ex = path[depth].p_ext;
     ee_block = le32_to_cpu(ex->ee_block);
     ee_len = ext4_ext_get_actual_len(ex);
     unwritten = ext4_ext_is_unwritten(ex);
 
     if (map->m_lblk + map->m_len < ee_block + ee_len) {
         split_flag1 = split_flag & EXT4_EXT_MAY_ZEROOUT;
         flags1 = flags | EXT4_GET_BLOCKS_PRE_IO;
         if (unwritten)
             split_flag1 |= EXT4_EXT_MARK_UNWRIT1 |
                        EXT4_EXT_MARK_UNWRIT2;
         if (split_flag & EXT4_EXT_DATA_VALID2)
             split_flag1 |= EXT4_EXT_DATA_VALID1;
         err = ext4_split_extent_at(handle, inode, ppath,
                 map->m_lblk + map->m_len, split_flag1, flags1);
         if (err)
             goto out;
     } else {
         allocated = ee_len - (map->m_lblk - ee_block);
     }
     /*
      * Update path is required because previous ext4_split_extent_at() may
      * result in split of original leaf or extent zeroout.
      */
     path = ext4_find_extent(inode, map->m_lblk, ppath, flags);
     if (IS_ERR(path))
         return PTR_ERR(path);
     depth = ext_depth(inode);
     ex = path[depth].p_ext;
     if (!ex) {
         EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
                  (unsigned long) map->m_lblk);
         return -EFSCORRUPTED;
     }
     unwritten = ext4_ext_is_unwritten(ex);
 
     if (map->m_lblk >= ee_block) {
         split_flag1 = split_flag & EXT4_EXT_DATA_VALID2;
         if (unwritten) {
             split_flag1 |= EXT4_EXT_MARK_UNWRIT1;
             split_flag1 |= split_flag & (EXT4_EXT_MAY_ZEROOUT |
                              EXT4_EXT_MARK_UNWRIT2);
         }
         err = ext4_split_extent_at(handle, inode, ppath,
                 map->m_lblk, split_flag1, flags);
         if (err)
             goto out;
     }
 
     ext4_ext_show_leaf(inode, path);
 out:
     return err ? err : allocated;
 }
 
 /*
  * This function is called by ext4_ext_map_blocks() if someone tries to write
  * to an unwritten extent. It may result in splitting the unwritten
  * extent into multiple extents (up to three - one initialized and two
  * unwritten).
  * There are three possibilities:
  *   a> There is no split required: Entire extent should be initialized
  *   b> Splits in two extents: Write is happening at either end of the extent
  *   c> Splits in three extents: Somone is writing in middle of the extent
  *
  * Pre-conditions:
  *  - The extent pointed to by 'path' is unwritten.
  *  - The extent pointed to by 'path' contains a superset
  *    of the logical span [map->m_lblk, map->m_lblk + map->m_len).
  *
  * Post-conditions on success:
  *  - the returned value is the number of blocks beyond map->l_lblk
  *    that are allocated and initialized.
  *    It is guaranteed to be >= map->m_len.
  */
 static int ext4_ext_convert_to_initialized(handle_t *handle,
                        struct inode *inode,
                        struct ext4_map_blocks *map,
                        struct ext4_ext_path **ppath,
                        int flags)
 {
     struct ext4_ext_path *path = *ppath;
     struct ext4_sb_info *sbi;
     struct ext4_extent_header *eh;
     struct ext4_map_blocks split_map;
     struct ext4_extent zero_ex1, zero_ex2;
     struct ext4_extent *ex, *abut_ex;
     ext4_lblk_t ee_block, eof_block;
     unsigned int ee_len, depth, map_len = map->m_len;
     int allocated = 0, max_zeroout = 0;
     int err = 0;
     int split_flag = EXT4_EXT_DATA_VALID2;
 
     ext_debug(inode, "logical block %llu, max_blocks %u\n",
           (unsigned long long)map->m_lblk, map_len);
 
     sbi = EXT4_SB(inode->i_sb);
     eof_block = (EXT4_I(inode)->i_disksize + inode->i_sb->s_blocksize - 1)
             >> inode->i_sb->s_blocksize_bits;
     if (eof_block < map->m_lblk + map_len)
         eof_block = map->m_lblk + map_len;
 
     depth = ext_depth(inode);
     eh = path[depth].p_hdr;
     ex = path[depth].p_ext;
     ee_block = le32_to_cpu(ex->ee_block);
     ee_len = ext4_ext_get_actual_len(ex);
     zero_ex1.ee_len = 0;
     zero_ex2.ee_len = 0;
 
     trace_ext4_ext_convert_to_initialized_enter(inode, map, ex);
 
     /* Pre-conditions */
     BUG_ON(!ext4_ext_is_unwritten(ex));
     BUG_ON(!in_range(map->m_lblk, ee_block, ee_len));
 
     /*
      * Attempt to transfer newly initialized blocks from the currently
      * unwritten extent to its neighbor. This is much cheaper
      * than an insertion followed by a merge as those involve costly
      * memmove() calls. Transferring to the left is the common case in
      * steady state for workloads doing fallocate(FALLOC_FL_KEEP_SIZE)
      * followed by append writes.
      *
      * Limitations of the current logic:
      *  - L1: we do not deal with writes covering the whole extent.
      *    This would require removing the extent if the transfer
      *    is possible.
      *  - L2: we only attempt to merge with an extent stored in the
      *    same extent tree node.
      */
     if ((map->m_lblk == ee_block) &&
         /* See if we can merge left */
         (map_len < ee_len) &&       /*L1*/
         (ex > EXT_FIRST_EXTENT(eh))) {  /*L2*/
         ext4_lblk_t prev_lblk;
         ext4_fsblk_t prev_pblk, ee_pblk;
         unsigned int prev_len;
 
         abut_ex = ex - 1;
         prev_lblk = le32_to_cpu(abut_ex->ee_block);
         prev_len = ext4_ext_get_actual_len(abut_ex);
         prev_pblk = ext4_ext_pblock(abut_ex);
         ee_pblk = ext4_ext_pblock(ex);
 
         /*
          * A transfer of blocks from 'ex' to 'abut_ex' is allowed
          * upon those conditions:
          * - C1: abut_ex is initialized,
          * - C2: abut_ex is logically abutting ex,
          * - C3: abut_ex is physically abutting ex,
          * - C4: abut_ex can receive the additional blocks without
          *   overflowing the (initialized) length limit.
          */
         if ((!ext4_ext_is_unwritten(abut_ex)) &&        /*C1*/
             ((prev_lblk + prev_len) == ee_block) &&     /*C2*/
             ((prev_pblk + prev_len) == ee_pblk) &&      /*C3*/
             (prev_len < (EXT_INIT_MAX_LEN - map_len))) {    /*C4*/
             err = ext4_ext_get_access(handle, inode, path + depth);
             if (err)
                 goto out;
 
             trace_ext4_ext_convert_to_initialized_fastpath(inode,
                 map, ex, abut_ex);
 
             /* Shift the start of ex by 'map_len' blocks */
             ex->ee_block = cpu_to_le32(ee_block + map_len);
             ext4_ext_store_pblock(ex, ee_pblk + map_len);
             ex->ee_len = cpu_to_le16(ee_len - map_len);
             ext4_ext_mark_unwritten(ex); /* Restore the flag */
 
             /* Extend abut_ex by 'map_len' blocks */
             abut_ex->ee_len = cpu_to_le16(prev_len + map_len);
 
             /* Result: number of initialized blocks past m_lblk */
             allocated = map_len;
         }
     } else if (((map->m_lblk + map_len) == (ee_block + ee_len)) &&
            (map_len < ee_len) &&    /*L1*/
            ex < EXT_LAST_EXTENT(eh)) {  /*L2*/
         /* See if we can merge right */
         ext4_lblk_t next_lblk;
         ext4_fsblk_t next_pblk, ee_pblk;
         unsigned int next_len;
 
         abut_ex = ex + 1;
         next_lblk = le32_to_cpu(abut_ex->ee_block);
         next_len = ext4_ext_get_actual_len(abut_ex);
         next_pblk = ext4_ext_pblock(abut_ex);
         ee_pblk = ext4_ext_pblock(ex);
 
         /*
          * A transfer of blocks from 'ex' to 'abut_ex' is allowed
          * upon those conditions:
          * - C1: abut_ex is initialized,
          * - C2: abut_ex is logically abutting ex,
          * - C3: abut_ex is physically abutting ex,
          * - C4: abut_ex can receive the additional blocks without
          *   overflowing the (initialized) length limit.
          */
         if ((!ext4_ext_is_unwritten(abut_ex)) &&        /*C1*/
             ((map->m_lblk + map_len) == next_lblk) &&       /*C2*/
             ((ee_pblk + ee_len) == next_pblk) &&        /*C3*/
             (next_len < (EXT_INIT_MAX_LEN - map_len))) {    /*C4*/
             err = ext4_ext_get_access(handle, inode, path + depth);
             if (err)
                 goto out;
 
             trace_ext4_ext_convert_to_initialized_fastpath(inode,
                 map, ex, abut_ex);
 
             /* Shift the start of abut_ex by 'map_len' blocks */
             abut_ex->ee_block = cpu_to_le32(next_lblk - map_len);
             ext4_ext_store_pblock(abut_ex, next_pblk - map_len);
             ex->ee_len = cpu_to_le16(ee_len - map_len);
             ext4_ext_mark_unwritten(ex); /* Restore the flag */
 
             /* Extend abut_ex by 'map_len' blocks */
             abut_ex->ee_len = cpu_to_le16(next_len + map_len);
 
             /* Result: number of initialized blocks past m_lblk */
             allocated = map_len;
         }
     }
     if (allocated) {
         /* Mark the block containing both extents as dirty */
         err = ext4_ext_dirty(handle, inode, path + depth);
 
         /* Update path to point to the right extent */
         path[depth].p_ext = abut_ex;
         goto out;
     } else
         allocated = ee_len - (map->m_lblk - ee_block);
 
     WARN_ON(map->m_lblk < ee_block);
     /*
      * It is safe to convert extent to initialized via explicit
      * zeroout only if extent is fully inside i_size or new_size.
      */
     split_flag |= ee_block + ee_len <= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0;
 
     if (EXT4_EXT_MAY_ZEROOUT & split_flag)
         max_zeroout = sbi->s_extent_max_zeroout_kb >>
             (inode->i_sb->s_blocksize_bits - 10);
 
     /*
      * five cases:
      * 1. split the extent into three extents.
      * 2. split the extent into two extents, zeroout the head of the first
      *    extent.
      * 3. split the extent into two extents, zeroout the tail of the second
      *    extent.
      * 4. split the extent into two extents with out zeroout.
      * 5. no splitting needed, just possibly zeroout the head and / or the
      *    tail of the extent.
      */
     split_map.m_lblk = map->m_lblk;
     split_map.m_len = map->m_len;
 
     if (max_zeroout && (allocated > split_map.m_len)) {
         if (allocated <= max_zeroout) {
             /* case 3 or 5 */
             zero_ex1.ee_block =
                  cpu_to_le32(split_map.m_lblk +
                          split_map.m_len);
             zero_ex1.ee_len =
                 cpu_to_le16(allocated - split_map.m_len);
             ext4_ext_store_pblock(&zero_ex1,
                 ext4_ext_pblock(ex) + split_map.m_lblk +
                 split_map.m_len - ee_block);
             err = ext4_ext_zeroout(inode, &zero_ex1);
             if (err)
                 goto fallback;
             split_map.m_len = allocated;
         }
         if (split_map.m_lblk - ee_block + split_map.m_len <
                                 max_zeroout) {
             /* case 2 or 5 */
             if (split_map.m_lblk != ee_block) {
                 zero_ex2.ee_block = ex->ee_block;
                 zero_ex2.ee_len = cpu_to_le16(split_map.m_lblk -
                             ee_block);
                 ext4_ext_store_pblock(&zero_ex2,
                               ext4_ext_pblock(ex));
                 err = ext4_ext_zeroout(inode, &zero_ex2);
                 if (err)
                     goto fallback;
             }
 
             split_map.m_len += split_map.m_lblk - ee_block;
             split_map.m_lblk = ee_block;
             allocated = map->m_len;
         }
     }
 
 fallback:
     err = ext4_split_extent(handle, inode, ppath, &split_map, split_flag,
                 flags);
     if (err > 0)
         err = 0;
 out:
     /* If we have gotten a failure, don't zero out status tree */
     if (!err) {
         err = ext4_zeroout_es(inode, &zero_ex1);
         if (!err)
             err = ext4_zeroout_es(inode, &zero_ex2);
     }
     return err ? err : allocated;
 }
 
 /*
  * This function is called by ext4_ext_map_blocks() from
  * ext4_get_blocks_dio_write() when DIO to write
  * to an unwritten extent.
  *
  * Writing to an unwritten extent may result in splitting the unwritten
  * extent into multiple initialized/unwritten extents (up to three)
  * There are three possibilities:
  *   a> There is no split required: Entire extent should be unwritten
  *   b> Splits in two extents: Write is happening at either end of the extent
  *   c> Splits in three extents: Somone is writing in middle of the extent
  *
  * This works the same way in the case of initialized -> unwritten conversion.
  *
  * One of more index blocks maybe needed if the extent tree grow after
  * the unwritten extent split. To prevent ENOSPC occur at the IO
  * complete, we need to split the unwritten extent before DIO submit
  * the IO. The unwritten extent called at this time will be split
  * into three unwritten extent(at most). After IO complete, the part
  * being filled will be convert to initialized by the end_io callback function
  * via ext4_convert_unwritten_extents().
  *
  * Returns the size of unwritten extent to be written on success.
  */
 static int ext4_split_convert_extents(handle_t *handle,
                     struct inode *inode,
                     struct ext4_map_blocks *map,
                     struct ext4_ext_path **ppath,
                     int flags)
 {
     struct ext4_ext_path *path = *ppath;
     ext4_lblk_t eof_block;
     ext4_lblk_t ee_block;
     struct ext4_extent *ex;
     unsigned int ee_len;
     int split_flag = 0, depth;
 
     ext_debug(inode, "logical block %llu, max_blocks %u\n",
           (unsigned long long)map->m_lblk, map->m_len);
 
     eof_block = (EXT4_I(inode)->i_disksize + inode->i_sb->s_blocksize - 1)
             >> inode->i_sb->s_blocksize_bits;
     if (eof_block < map->m_lblk + map->m_len)
         eof_block = map->m_lblk + map->m_len;
     /*
      * It is safe to convert extent to initialized via explicit
      * zeroout only if extent is fully inside i_size or new_size.
      */
     depth = ext_depth(inode);
     ex = path[depth].p_ext;
     ee_block = le32_to_cpu(ex->ee_block);
     ee_len = ext4_ext_get_actual_len(ex);
 
     /* Convert to unwritten */
     if (flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN) {
         split_flag |= EXT4_EXT_DATA_VALID1;
     /* Convert to initialized */
     } else if (flags & EXT4_GET_BLOCKS_CONVERT) {
         split_flag |= ee_block + ee_len <= eof_block ?
                   EXT4_EXT_MAY_ZEROOUT : 0;
         split_flag |= (EXT4_EXT_MARK_UNWRIT2 | EXT4_EXT_DATA_VALID2);
     }
     flags |= EXT4_GET_BLOCKS_PRE_IO;
     return ext4_split_extent(handle, inode, ppath, map, split_flag, flags);
 }
 
 static int ext4_convert_unwritten_extents_endio(handle_t *handle,
                         struct inode *inode,
                         struct ext4_map_blocks *map,
                         struct ext4_ext_path **ppath)
 {
     struct ext4_ext_path *path = *ppath;
     struct ext4_extent *ex;
     ext4_lblk_t ee_block;
     unsigned int ee_len;
     int depth;
     int err = 0;
 
     depth = ext_depth(inode);
     ex = path[depth].p_ext;
     ee_block = le32_to_cpu(ex->ee_block);
     ee_len = ext4_ext_get_actual_len(ex);
 
     ext_debug(inode, "logical block %llu, max_blocks %u\n",
           (unsigned long long)ee_block, ee_len);
 
     /* If extent is larger than requested it is a clear sign that we still
      * have some extent state machine issues left. So extent_split is still
      * required.
      * TODO: Once all related issues will be fixed this situation should be
      * illegal.
      */
     if (ee_block != map->m_lblk || ee_len > map->m_len) {
 #ifdef CONFIG_EXT4_DEBUG
         ext4_warning(inode->i_sb, "Inode (%ld) finished: extent logical block %llu,"
                  " len %u; IO logical block %llu, len %u",
                  inode->i_ino, (unsigned long long)ee_block, ee_len,
                  (unsigned long long)map->m_lblk, map->m_len);
 #endif
         err = ext4_split_convert_extents(handle, inode, map, ppath,
                          EXT4_GET_BLOCKS_CONVERT);
         if (err < 0)
             return err;
         path = ext4_find_extent(inode, map->m_lblk, ppath, 0);
         if (IS_ERR(path))
             return PTR_ERR(path);
         depth = ext_depth(inode);
         ex = path[depth].p_ext;
     }
 
     err = ext4_ext_get_access(handle, inode, path + depth);
     if (err)
         goto out;
     /* first mark the extent as initialized */
     ext4_ext_mark_initialized(ex);
 
     /* note: ext4_ext_correct_indexes() isn't needed here because
      * borders are not changed
      */
     ext4_ext_try_to_merge(handle, inode, path, ex);
 
     /* Mark modified extent as dirty */
     err = ext4_ext_dirty(handle, inode, path + path->p_depth);
 out:
     ext4_ext_show_leaf(inode, path);
     return err;
 }
 
 static int
 convert_initialized_extent(handle_t *handle, struct inode *inode,
                struct ext4_map_blocks *map,
                struct ext4_ext_path **ppath,
                unsigned int *allocated)
 {
     struct ext4_ext_path *path = *ppath;
     struct ext4_extent *ex;
     ext4_lblk_t ee_block;
     unsigned int ee_len;
     int depth;
     int err = 0;
 
     /*
      * Make sure that the extent is no bigger than we support with
      * unwritten extent
      */
     if (map->m_len > EXT_UNWRITTEN_MAX_LEN)
         map->m_len = EXT_UNWRITTEN_MAX_LEN / 2;
 
     depth = ext_depth(inode);
     ex = path[depth].p_ext;
     ee_block = le32_to_cpu(ex->ee_block);
     ee_len = ext4_ext_get_actual_len(ex);
 
     ext_debug(inode, "logical block %llu, max_blocks %u\n",
           (unsigned long long)ee_block, ee_len);
 
     if (ee_block != map->m_lblk || ee_len > map->m_len) {
         err = ext4_split_convert_extents(handle, inode, map, ppath,
                 EXT4_GET_BLOCKS_CONVERT_UNWRITTEN);
         if (err < 0)
             return err;
         path = ext4_find_extent(inode, map->m_lblk, ppath, 0);
         if (IS_ERR(path))
             return PTR_ERR(path);
         depth = ext_depth(inode);
         ex = path[depth].p_ext;
         if (!ex) {
             EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
                      (unsigned long) map->m_lblk);
             return -EFSCORRUPTED;
         }
     }
 
     err = ext4_ext_get_access(handle, inode, path + depth);
     if (err)
         return err;
     /* first mark the extent as unwritten */
     ext4_ext_mark_unwritten(ex);
 
     /* note: ext4_ext_correct_indexes() isn't needed here because
      * borders are not changed
      */
     ext4_ext_try_to_merge(handle, inode, path, ex);
 
     /* Mark modified extent as dirty */
     err = ext4_ext_dirty(handle, inode, path + path->p_depth);
     if (err)
         return err;
     ext4_ext_show_leaf(inode, path);
 
     ext4_update_inode_fsync_trans(handle, inode, 1);
 
     map->m_flags |= EXT4_MAP_UNWRITTEN;
     if (*allocated > map->m_len)
         *allocated = map->m_len;
     map->m_len = *allocated;
     return 0;
 }
 
 static int
 ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
             struct ext4_map_blocks *map,
             struct ext4_ext_path **ppath, int flags,
             unsigned int allocated, ext4_fsblk_t newblock)
 {
     struct ext4_ext_path __maybe_unused *path = *ppath;
     int ret = 0;
     int err = 0;
 
     ext_debug(inode, "logical block %llu, max_blocks %u, flags 0x%x, allocated %u\n",
           (unsigned long long)map->m_lblk, map->m_len, flags,
           allocated);
     ext4_ext_show_leaf(inode, path);
 
     /*
      * When writing into unwritten space, we should not fail to
      * allocate metadata blocks for the new extent block if needed.
      */
     flags |= EXT4_GET_BLOCKS_METADATA_NOFAIL;
 
     trace_ext4_ext_handle_unwritten_extents(inode, map, flags,
                             allocated, newblock);
 
     /* get_block() before submitting IO, split the extent */
     if (flags & EXT4_GET_BLOCKS_PRE_IO) {
         ret = ext4_split_convert_extents(handle, inode, map, ppath,
                      flags | EXT4_GET_BLOCKS_CONVERT);
         if (ret < 0) {
             err = ret;
             goto out2;
         }
         /*
          * shouldn't get a 0 return when splitting an extent unless
          * m_len is 0 (bug) or extent has been corrupted
          */
         if (unlikely(ret == 0)) {
             EXT4_ERROR_INODE(inode,
                      "unexpected ret == 0, m_len = %u",
                      map->m_len);
             err = -EFSCORRUPTED;
             goto out2;
         }
         map->m_flags |= EXT4_MAP_UNWRITTEN;
         goto out;
     }
     /* IO end_io complete, convert the filled extent to written */
     if (flags & EXT4_GET_BLOCKS_CONVERT) {
         err = ext4_convert_unwritten_extents_endio(handle, inode, map,
                                ppath);
         if (err < 0)
             goto out2;
         ext4_update_inode_fsync_trans(handle, inode, 1);
         goto map_out;
     }
     /* buffered IO cases */
     /*
      * repeat fallocate creation request
      * we already have an unwritten extent
      */
     if (flags & EXT4_GET_BLOCKS_UNWRIT_EXT) {
         map->m_flags |= EXT4_MAP_UNWRITTEN;
         goto map_out;
     }
 
     /* buffered READ or buffered write_begin() lookup */
     if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
         /*
          * We have blocks reserved already.  We
          * return allocated blocks so that delalloc
          * won't do block reservation for us.  But
          * the buffer head will be unmapped so that
          * a read from the block returns 0s.
          */
         map->m_flags |= EXT4_MAP_UNWRITTEN;
         goto out1;
     }
 
     /*
      * Default case when (flags & EXT4_GET_BLOCKS_CREATE) == 1.
      * For buffered writes, at writepage time, etc.  Convert a
      * discovered unwritten extent to written.
      */
     ret = ext4_ext_convert_to_initialized(handle, inode, map, ppath, flags);
     if (ret < 0) {
         err = ret;
         goto out2;
     }
     ext4_update_inode_fsync_trans(handle, inode, 1);
     /*
      * shouldn't get a 0 return when converting an unwritten extent
      * unless m_len is 0 (bug) or extent has been corrupted
      */
     if (unlikely(ret == 0)) {
         EXT4_ERROR_INODE(inode, "unexpected ret == 0, m_len = %u",
                  map->m_len);
         err = -EFSCORRUPTED;
         goto out2;
     }
 
 out:
     allocated = ret;
     map->m_flags |= EXT4_MAP_NEW;
 map_out:
     map->m_flags |= EXT4_MAP_MAPPED;
 out1:
     map->m_pblk = newblock;
     if (allocated > map->m_len)
         allocated = map->m_len;
     map->m_len = allocated;
     ext4_ext_show_leaf(inode, path);
 out2:
     return err ? err : allocated;
 }
 
 /*
  * get_implied_cluster_alloc - check to see if the requested
  * allocation (in the map structure) overlaps with a cluster already
  * allocated in an extent.
  *  @sb The filesystem superblock structure
  *  @map    The requested lblk->pblk mapping
  *  @ex The extent structure which might contain an implied
  *          cluster allocation
  *
  * This function is called by ext4_ext_map_blocks() after we failed to
  * find blocks that were already in the inode's extent tree.  Hence,
  * we know that the beginning of the requested region cannot overlap
  * the extent from the inode's extent tree.  There are three cases we
  * want to catch.  The first is this case:
  *
  *       |--- cluster # N--|
  *    |--- extent ---|  |---- requested region ---|
  *          |==========|
  *
  * The second case that we need to test for is this one:
  *
  *   |--------- cluster # N ----------------|
  *     |--- requested region --|   |------- extent ----|
  *     |=======================|
  *
  * The third case is when the requested region lies between two extents
  * within the same cluster:
  *          |------------- cluster # N-------------|
  * |----- ex -----|                  |---- ex_right ----|
  *                  |------ requested region ------|
  *                  |================|
  *
  * In each of the above cases, we need to set the map->m_pblk and
  * map->m_len so it corresponds to the return the extent labelled as
  * "|====|" from cluster #N, since it is already in use for data in
  * cluster EXT4_B2C(sbi, map->m_lblk).  We will then return 1 to
  * signal to ext4_ext_map_blocks() that map->m_pblk should be treated
  * as a new "allocated" block region.  Otherwise, we will return 0 and
  * ext4_ext_map_blocks() will then allocate one or more new clusters
  * by calling ext4_mb_new_blocks().
  */
 static int get_implied_cluster_alloc(struct super_block *sb,
                      struct ext4_map_blocks *map,
                      struct ext4_extent *ex,
                      struct ext4_ext_path *path)
 {
     struct ext4_sb_info *sbi = EXT4_SB(sb);
     ext4_lblk_t c_offset = EXT4_LBLK_COFF(sbi, map->m_lblk);
     ext4_lblk_t ex_cluster_start, ex_cluster_end;
     ext4_lblk_t rr_cluster_start;
     ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
     ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
     unsigned short ee_len = ext4_ext_get_actual_len(ex);
 
     /* The extent passed in that we are trying to match */
     ex_cluster_start = EXT4_B2C(sbi, ee_block);
     ex_cluster_end = EXT4_B2C(sbi, ee_block + ee_len - 1);
 
     /* The requested region passed into ext4_map_blocks() */
     rr_cluster_start = EXT4_B2C(sbi, map->m_lblk);
 
     if ((rr_cluster_start == ex_cluster_end) ||
         (rr_cluster_start == ex_cluster_start)) {
         if (rr_cluster_start == ex_cluster_end)
             ee_start += ee_len - 1;
         map->m_pblk = EXT4_PBLK_CMASK(sbi, ee_start) + c_offset;
         map->m_len = min(map->m_len,
                  (unsigned) sbi->s_cluster_ratio - c_offset);
         /*
          * Check for and handle this case:
          *
          *   |--------- cluster # N-------------|
          *             |------- extent ----|
          *     |--- requested region ---|
          *     |===========|
          */
 
         if (map->m_lblk < ee_block)
             map->m_len = min(map->m_len, ee_block - map->m_lblk);
 
         /*
          * Check for the case where there is already another allocated
          * block to the right of 'ex' but before the end of the cluster.
          *
          *          |------------- cluster # N-------------|
          * |----- ex -----|                  |---- ex_right ----|
          *                  |------ requested region ------|
          *                  |================|
          */
         if (map->m_lblk > ee_block) {
             ext4_lblk_t next = ext4_ext_next_allocated_block(path);
             map->m_len = min(map->m_len, next - map->m_lblk);
         }
 
         trace_ext4_get_implied_cluster_alloc_exit(sb, map, 1);
         return 1;
     }
 
     trace_ext4_get_implied_cluster_alloc_exit(sb, map, 0);
     return 0;
 }
 
 
 /*
  * Block allocation/map/preallocation routine for extents based files
  *
  *
  * Need to be called with
  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
  * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
  *
  * return > 0, number of blocks already mapped/allocated
  *          if create == 0 and these are pre-allocated blocks
  *              buffer head is unmapped
  *          otherwise blocks are mapped
  *
  * return = 0, if plain look up failed (blocks have not been allocated)
  *          buffer head is unmapped
  *
  * return < 0, error case.
  */
 int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
             struct ext4_map_blocks *map, int flags)
 {
     struct ext4_ext_path *path = NULL;
     struct ext4_extent newex, *ex, ex2;
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     ext4_fsblk_t newblock = 0, pblk;
     int err = 0, depth, ret;
     unsigned int allocated = 0, offset = 0;
     unsigned int allocated_clusters = 0;
     struct ext4_allocation_request ar;
     ext4_lblk_t cluster_offset;
 
     ext_debug(inode, "blocks %u/%u requested\n", map->m_lblk, map->m_len);
     trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
 
     /* find extent for this block */
     path = ext4_find_extent(inode, map->m_lblk, NULL, 0);
     if (IS_ERR(path)) {
         err = PTR_ERR(path);
         path = NULL;
         goto out;
     }
 
     depth = ext_depth(inode);
 
     /*
      * consistent leaf must not be empty;
      * this situation is possible, though, _during_ tree modification;
      * this is why assert can't be put in ext4_find_extent()
      */
     if (unlikely(path[depth].p_ext == NULL && depth != 0)) {
         EXT4_ERROR_INODE(inode, "bad extent address "
                  "lblock: %lu, depth: %d pblock %lld",
                  (unsigned long) map->m_lblk, depth,
                  path[depth].p_block);
         err = -EFSCORRUPTED;
         goto out;
     }
 
     ex = path[depth].p_ext;
     if (ex) {
         ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
         ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
         unsigned short ee_len;
 
 
         /*
          * unwritten extents are treated as holes, except that
          * we split out initialized portions during a write.
          */
         ee_len = ext4_ext_get_actual_len(ex);
 
         trace_ext4_ext_show_extent(inode, ee_block, ee_start, ee_len);
 
         /* if found extent covers block, simply return it */
         if (in_range(map->m_lblk, ee_block, ee_len)) {
             newblock = map->m_lblk - ee_block + ee_start;
             /* number of remaining blocks in the extent */
             allocated = ee_len - (map->m_lblk - ee_block);
             ext_debug(inode, "%u fit into %u:%d -> %llu\n",
                   map->m_lblk, ee_block, ee_len, newblock);
 
             /*
              * If the extent is initialized check whether the
              * caller wants to convert it to unwritten.
              */
             if ((!ext4_ext_is_unwritten(ex)) &&
                 (flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN)) {
                 err = convert_initialized_extent(handle,
                     inode, map, &path, &allocated);
                 goto out;
             } else if (!ext4_ext_is_unwritten(ex)) {
                 map->m_flags |= EXT4_MAP_MAPPED;
                 map->m_pblk = newblock;
                 if (allocated > map->m_len)
                     allocated = map->m_len;
                 map->m_len = allocated;
                 ext4_ext_show_leaf(inode, path);
                 goto out;
             }
 
             ret = ext4_ext_handle_unwritten_extents(
                 handle, inode, map, &path, flags,
                 allocated, newblock);
             if (ret < 0)
                 err = ret;
             else
                 allocated = ret;
             goto out;
         }
     }
 
     /*
      * requested block isn't allocated yet;
      * we couldn't try to create block if create flag is zero
      */
     if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
         ext4_lblk_t hole_start, hole_len;
 
         hole_start = map->m_lblk;
         hole_len = ext4_ext_determine_hole(inode, path, &hole_start);
         /*
          * put just found gap into cache to speed up
          * subsequent requests
          */
         ext4_ext_put_gap_in_cache(inode, hole_start, hole_len);
 
         /* Update hole_len to reflect hole size after map->m_lblk */
         if (hole_start != map->m_lblk)
             hole_len -= map->m_lblk - hole_start;
         map->m_pblk = 0;
         map->m_len = min_t(unsigned int, map->m_len, hole_len);
 
         goto out;
     }
 
     /*
      * Okay, we need to do block allocation.
      */
     newex.ee_block = cpu_to_le32(map->m_lblk);
     cluster_offset = EXT4_LBLK_COFF(sbi, map->m_lblk);
 
     /*
      * If we are doing bigalloc, check to see if the extent returned
      * by ext4_find_extent() implies a cluster we can use.
      */
     if (cluster_offset && ex &&
         get_implied_cluster_alloc(inode->i_sb, map, ex, path)) {
         ar.len = allocated = map->m_len;
         newblock = map->m_pblk;
         goto got_allocated_blocks;
     }
 
     /* find neighbour allocated blocks */
     ar.lleft = map->m_lblk;
     err = ext4_ext_search_left(inode, path, &ar.lleft, &ar.pleft);
     if (err)
         goto out;
     ar.lright = map->m_lblk;
     err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright, &ex2);
     if (err < 0)
         goto out;
 
     /* Check if the extent after searching to the right implies a
      * cluster we can use. */
     if ((sbi->s_cluster_ratio > 1) && err &&
         get_implied_cluster_alloc(inode->i_sb, map, &ex2, path)) {
         ar.len = allocated = map->m_len;
         newblock = map->m_pblk;
         goto got_allocated_blocks;
     }
 
     /*
      * See if request is beyond maximum number of blocks we can have in
      * a single extent. For an initialized extent this limit is
      * EXT_INIT_MAX_LEN and for an unwritten extent this limit is
      * EXT_UNWRITTEN_MAX_LEN.
      */
     if (map->m_len > EXT_INIT_MAX_LEN &&
         !(flags & EXT4_GET_BLOCKS_UNWRIT_EXT))
         map->m_len = EXT_INIT_MAX_LEN;
     else if (map->m_len > EXT_UNWRITTEN_MAX_LEN &&
          (flags & EXT4_GET_BLOCKS_UNWRIT_EXT))
         map->m_len = EXT_UNWRITTEN_MAX_LEN;
 
     /* Check if we can really insert (m_lblk)::(m_lblk + m_len) extent */
     newex.ee_len = cpu_to_le16(map->m_len);
     err = ext4_ext_check_overlap(sbi, inode, &newex, path);
     if (err)
         allocated = ext4_ext_get_actual_len(&newex);
     else
         allocated = map->m_len;
 
     /* allocate new block */
     ar.inode = inode;
     ar.goal = ext4_ext_find_goal(inode, path, map->m_lblk);
     ar.logical = map->m_lblk;
     /*
      * We calculate the offset from the beginning of the cluster
      * for the logical block number, since when we allocate a
      * physical cluster, the physical block should start at the
      * same offset from the beginning of the cluster.  This is
      * needed so that future calls to get_implied_cluster_alloc()
      * work correctly.
      */
     offset = EXT4_LBLK_COFF(sbi, map->m_lblk);
     ar.len = EXT4_NUM_B2C(sbi, offset+allocated);
     ar.goal -= offset;
     ar.logical -= offset;
     if (S_ISREG(inode->i_mode))
         ar.flags = EXT4_MB_HINT_DATA;
     else
         /* disable in-core preallocation for non-regular files */
         ar.flags = 0;
     if (flags & EXT4_GET_BLOCKS_NO_NORMALIZE)
         ar.flags |= EXT4_MB_HINT_NOPREALLOC;
     if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
         ar.flags |= EXT4_MB_DELALLOC_RESERVED;
     if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
         ar.flags |= EXT4_MB_USE_RESERVED;
     newblock = ext4_mb_new_blocks(handle, &ar, &err);
     if (!newblock)
         goto out;
     allocated_clusters = ar.len;
     ar.len = EXT4_C2B(sbi, ar.len) - offset;
     ext_debug(inode, "allocate new block: goal %llu, found %llu/%u, requested %u\n",
           ar.goal, newblock, ar.len, allocated);
     if (ar.len > allocated)
         ar.len = allocated;
 
 got_allocated_blocks:
     /* try to insert new extent into found leaf and return */
     pblk = newblock + offset;
     ext4_ext_store_pblock(&newex, pblk);
     newex.ee_len = cpu_to_le16(ar.len);
     /* Mark unwritten */
     if (flags & EXT4_GET_BLOCKS_UNWRIT_EXT) {
         ext4_ext_mark_unwritten(&newex);
         map->m_flags |= EXT4_MAP_UNWRITTEN;
     }
 
     err = ext4_ext_insert_extent(handle, inode, &path, &newex, flags);
     if (err) {
         if (allocated_clusters) {
             int fb_flags = 0;
 
             /*
              * free data blocks we just allocated.
              * not a good idea to call discard here directly,
              * but otherwise we'd need to call it every free().
              */
             ext4_discard_preallocations(inode, 0);
             if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
                 fb_flags = EXT4_FREE_BLOCKS_NO_QUOT_UPDATE;
             ext4_free_blocks(handle, inode, NULL, newblock,
                      EXT4_C2B(sbi, allocated_clusters),
                      fb_flags);
         }
         goto out;
     }
 
     /*
      * Reduce the reserved cluster count to reflect successful deferred
      * allocation of delayed allocated clusters or direct allocation of
      * clusters discovered to be delayed allocated.  Once allocated, a
      * cluster is not included in the reserved count.
      */
     if (test_opt(inode->i_sb, DELALLOC) && allocated_clusters) {
         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {
             /*
              * When allocating delayed allocated clusters, simply
              * reduce the reserved cluster count and claim quota
              */
             ext4_da_update_reserve_space(inode, allocated_clusters,
                             1);
         } else {
             ext4_lblk_t lblk, len;
             unsigned int n;
 
             /*
              * When allocating non-delayed allocated clusters
              * (from fallocate, filemap, DIO, or clusters
              * allocated when delalloc has been disabled by
              * ext4_nonda_switch), reduce the reserved cluster
              * count by the number of allocated clusters that
              * have previously been delayed allocated.  Quota
              * has been claimed by ext4_mb_new_blocks() above,
              * so release the quota reservations made for any
              * previously delayed allocated clusters.
              */
             lblk = EXT4_LBLK_CMASK(sbi, map->m_lblk);
             len = allocated_clusters << sbi->s_cluster_bits;
             n = ext4_es_delayed_clu(inode, lblk, len);
             if (n > 0)
                 ext4_da_update_reserve_space(inode, (int) n, 0);
         }
     }
 
     /*
      * Cache the extent and update transaction to commit on fdatasync only
      * when it is _not_ an unwritten extent.
      */
     if ((flags & EXT4_GET_BLOCKS_UNWRIT_EXT) == 0)
         ext4_update_inode_fsync_trans(handle, inode, 1);
     else
         ext4_update_inode_fsync_trans(handle, inode, 0);
 
     map->m_flags |= (EXT4_MAP_NEW | EXT4_MAP_MAPPED);
     map->m_pblk = pblk;
     map->m_len = ar.len;
     allocated = map->m_len;
     ext4_ext_show_leaf(inode, path);
 out:
     ext4_ext_drop_refs(path);
     kfree(path);
 
     trace_ext4_ext_map_blocks_exit(inode, flags, map,
                        err ? err : allocated);
     return err ? err : allocated;
 }
 
 int ext4_ext_truncate(handle_t *handle, struct inode *inode)
 {
     struct super_block *sb = inode->i_sb;
     ext4_lblk_t last_block;
     int err = 0;
 
     /*
      * TODO: optimization is possible here.
      * Probably we need not scan at all,
      * because page truncation is enough.
      */
 
     /* we have to know where to truncate from in crash case */
     EXT4_I(inode)->i_disksize = inode->i_size;
     err = ext4_mark_inode_dirty(handle, inode);
     if (err)
         return err;
 
     last_block = (inode->i_size + sb->s_blocksize - 1)
             >> EXT4_BLOCK_SIZE_BITS(sb);
 retry:
     err = ext4_es_remove_extent(inode, last_block,
                     EXT_MAX_BLOCKS - last_block);
     if (err == -ENOMEM) {
         memalloc_retry_wait(GFP_ATOMIC);
         goto retry;
     }
     if (err)
         return err;
 retry_remove_space:
     err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
     if (err == -ENOMEM) {
         memalloc_retry_wait(GFP_ATOMIC);
         goto retry_remove_space;
     }
     return err;
 }
 
 static int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset,
                   ext4_lblk_t len, loff_t new_size,
                   int flags)
 {
     struct inode *inode = file_inode(file);
     handle_t *handle;
     int ret = 0, ret2 = 0, ret3 = 0;
     int retries = 0;
     int depth = 0;
     struct ext4_map_blocks map;
     unsigned int credits;
     loff_t epos;
 
     BUG_ON(!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS));
     map.m_lblk = offset;
     map.m_len = len;
     /*
      * Don't normalize the request if it can fit in one extent so
      * that it doesn't get unnecessarily split into multiple
      * extents.
      */
     if (len <= EXT_UNWRITTEN_MAX_LEN)
         flags |= EXT4_GET_BLOCKS_NO_NORMALIZE;
 
     /*
      * credits to insert 1 extent into extent tree
      */
     credits = ext4_chunk_trans_blocks(inode, len);
     depth = ext_depth(inode);
 
 retry:
     while (len) {
         /*
          * Recalculate credits when extent tree depth changes.
          */
         if (depth != ext_depth(inode)) {
             credits = ext4_chunk_trans_blocks(inode, len);
             depth = ext_depth(inode);
         }
 
         handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
                         credits);
         if (IS_ERR(handle)) {
             ret = PTR_ERR(handle);
             break;
         }
         ret = ext4_map_blocks(handle, inode, &map, flags);
         if (ret <= 0) {
             ext4_debug("inode #%lu: block %u: len %u: "
                    "ext4_ext_map_blocks returned %d",
                    inode->i_ino, map.m_lblk,
                    map.m_len, ret);
             ext4_mark_inode_dirty(handle, inode);
             ext4_journal_stop(handle);
             break;
         }
         /*
          * allow a full retry cycle for any remaining allocations
          */
         retries = 0;
         map.m_lblk += ret;
         map.m_len = len = len - ret;
         epos = (loff_t)map.m_lblk << inode->i_blkbits;
         inode->i_ctime = current_time(inode);
         if (new_size) {
             if (epos > new_size)
                 epos = new_size;
             if (ext4_update_inode_size(inode, epos) & 0x1)
                 inode->i_mtime = inode->i_ctime;
         }
         ret2 = ext4_mark_inode_dirty(handle, inode);
         ext4_update_inode_fsync_trans(handle, inode, 1);
         ret3 = ext4_journal_stop(handle);
         ret2 = ret3 ? ret3 : ret2;
         if (unlikely(ret2))
             break;
     }
     if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
         goto retry;
 
     return ret > 0 ? ret2 : ret;
 }
 
 static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len);
 
 static int ext4_insert_range(struct file *file, loff_t offset, loff_t len);
 
 static long ext4_zero_range(struct file *file, loff_t offset,
                 loff_t len, int mode)
 {
     struct inode *inode = file_inode(file);
     struct address_space *mapping = file->f_mapping;
     handle_t *handle = NULL;
     unsigned int max_blocks;
     loff_t new_size = 0;
     int ret = 0;
     int flags;
     int credits;
     int partial_begin, partial_end;
     loff_t start, end;
     ext4_lblk_t lblk;
     unsigned int blkbits = inode->i_blkbits;
 
     trace_ext4_zero_range(inode, offset, len, mode);
 
     /* Call ext4_force_commit to flush all data in case of data=journal. */
     if (ext4_should_journal_data(inode)) {
         ret = ext4_force_commit(inode->i_sb);
         if (ret)
             return ret;
     }
 
     /*
      * Round up offset. This is not fallocate, we need to zero out
      * blocks, so convert interior block aligned part of the range to
      * unwritten and possibly manually zero out unaligned parts of the
      * range.
      */
     start = round_up(offset, 1 << blkbits);
     end = round_down((offset + len), 1 << blkbits);
 
     if (start < offset || end > offset + len)
         return -EINVAL;
     partial_begin = offset & ((1 << blkbits) - 1);
     partial_end = (offset + len) & ((1 << blkbits) - 1);
 
     lblk = start >> blkbits;
     max_blocks = (end >> blkbits);
     if (max_blocks < lblk)
         max_blocks = 0;
     else
         max_blocks -= lblk;
 
     inode_lock(inode);
 
     /*
      * Indirect files do not support unwritten extents
      */
     if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
         ret = -EOPNOTSUPP;
         goto out_mutex;
     }
 
     if (!(mode & FALLOC_FL_KEEP_SIZE) &&
         (offset + len > inode->i_size ||
          offset + len > EXT4_I(inode)->i_disksize)) {
         new_size = offset + len;
         ret = inode_newsize_ok(inode, new_size);
         if (ret)
             goto out_mutex;
     }
 
     flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT;
 
     /* Wait all existing dio workers, newcomers will block on i_rwsem */
     inode_dio_wait(inode);
 
     ret = file_modified(file);
     if (ret)
         goto out_mutex;
 
     /* Preallocate the range including the unaligned edges */
     if (partial_begin || partial_end) {
         ret = ext4_alloc_file_blocks(file,
                 round_down(offset, 1 << blkbits) >> blkbits,
                 (round_up((offset + len), 1 << blkbits) -
                  round_down(offset, 1 << blkbits)) >> blkbits,
                 new_size, flags);
         if (ret)
             goto out_mutex;
 
     }
 
     /* Zero range excluding the unaligned edges */
     if (max_blocks > 0) {
         flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN |
               EXT4_EX_NOCACHE);
 
         /*
          * Prevent page faults from reinstantiating pages we have
          * released from page cache.
          */
         filemap_invalidate_lock(mapping);
 
         ret = ext4_break_layouts(inode);
         if (ret) {
             filemap_invalidate_unlock(mapping);
             goto out_mutex;
         }
 
         ret = ext4_update_disksize_before_punch(inode, offset, len);
         if (ret) {
             filemap_invalidate_unlock(mapping);
             goto out_mutex;
         }
         /* Now release the pages and zero block aligned part of pages */
         truncate_pagecache_range(inode, start, end - 1);
         inode->i_mtime = inode->i_ctime = current_time(inode);
 
         ret = ext4_alloc_file_blocks(file, lblk, max_blocks, new_size,
                          flags);
         filemap_invalidate_unlock(mapping);
         if (ret)
             goto out_mutex;
     }
     if (!partial_begin && !partial_end)
         goto out_mutex;
 
     /*
      * In worst case we have to writeout two nonadjacent unwritten
      * blocks and update the inode
      */
     credits = (2 * ext4_ext_index_trans_blocks(inode, 2)) + 1;
     if (ext4_should_journal_data(inode))
         credits += 2;
     handle = ext4_journal_start(inode, EXT4_HT_MISC, credits);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         ext4_std_error(inode->i_sb, ret);
         goto out_mutex;
     }
 
     inode->i_mtime = inode->i_ctime = current_time(inode);
     if (new_size)
         ext4_update_inode_size(inode, new_size);
     ret = ext4_mark_inode_dirty(handle, inode);
     if (unlikely(ret))
         goto out_handle;
     /* Zero out partial block at the edges of the range */
     ret = ext4_zero_partial_blocks(handle, inode, offset, len);
     if (ret >= 0)
         ext4_update_inode_fsync_trans(handle, inode, 1);
 
     if (file->f_flags & O_SYNC)
         ext4_handle_sync(handle);
 
 out_handle:
     ext4_journal_stop(handle);
 out_mutex:
     inode_unlock(inode);
     return ret;
 }
 
 /*
  * preallocate space for a file. This implements ext4's fallocate file
  * operation, which gets called from sys_fallocate system call.
  * For block-mapped files, posix_fallocate should fall back to the method
  * of writing zeroes to the required new blocks (the same behavior which is
  * expected for file systems which do not support fallocate() system call).
  */
 long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 {
     struct inode *inode = file_inode(file);
     loff_t new_size = 0;
     unsigned int max_blocks;
     int ret = 0;
     int flags;
     ext4_lblk_t lblk;
     unsigned int blkbits = inode->i_blkbits;
 
     /*
      * Encrypted inodes can't handle collapse range or insert
      * range since we would need to re-encrypt blocks with a
      * different IV or XTS tweak (which are based on the logical
      * block number).
      */
     if (IS_ENCRYPTED(inode) &&
         (mode & (FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE)))
         return -EOPNOTSUPP;
 
     /* Return error if mode is not supported */
     if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
              FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |
              FALLOC_FL_INSERT_RANGE))
         return -EOPNOTSUPP;
 
     inode_lock(inode);
     ret = ext4_convert_inline_data(inode);
     inode_unlock(inode);
     if (ret)
         goto exit;
 
     if (mode & FALLOC_FL_PUNCH_HOLE) {
         ret = ext4_punch_hole(file, offset, len);
         goto exit;
     }
 
     if (mode & FALLOC_FL_COLLAPSE_RANGE) {
         ret = ext4_collapse_range(file, offset, len);
         goto exit;
     }
 
     if (mode & FALLOC_FL_INSERT_RANGE) {
         ret = ext4_insert_range(file, offset, len);
         goto exit;
     }
 
     if (mode & FALLOC_FL_ZERO_RANGE) {
         ret = ext4_zero_range(file, offset, len, mode);
         goto exit;
     }
     trace_ext4_fallocate_enter(inode, offset, len, mode);
     lblk = offset >> blkbits;
 
     max_blocks = EXT4_MAX_BLOCKS(len, offset, blkbits);
     flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT;
 
     inode_lock(inode);
 
     /*
      * We only support preallocation for extent-based files only
      */
     if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
         ret = -EOPNOTSUPP;
         goto out;
     }
 
     if (!(mode & FALLOC_FL_KEEP_SIZE) &&
         (offset + len > inode->i_size ||
          offset + len > EXT4_I(inode)->i_disksize)) {
         new_size = offset + len;
         ret = inode_newsize_ok(inode, new_size);
         if (ret)
             goto out;
     }
 
     /* Wait all existing dio workers, newcomers will block on i_rwsem */
     inode_dio_wait(inode);
 
     ret = file_modified(file);
     if (ret)
         goto out;
 
     ret = ext4_alloc_file_blocks(file, lblk, max_blocks, new_size, flags);
     if (ret)
         goto out;
 
     if (file->f_flags & O_SYNC && EXT4_SB(inode->i_sb)->s_journal) {
         ret = ext4_fc_commit(EXT4_SB(inode->i_sb)->s_journal,
                     EXT4_I(inode)->i_sync_tid);
     }
 out:
     inode_unlock(inode);
     trace_ext4_fallocate_exit(inode, offset, max_blocks, ret);
 exit:
     return ret;
 }
 
 /*
  * This function convert a range of blocks to written extents
  * The caller of this function will pass the start offset and the size.
  * all unwritten extents within this range will be converted to
  * written extents.
  *
  * This function is called from the direct IO end io call back
  * function, to convert the fallocated extents after IO is completed.
  * Returns 0 on success.
  */
 int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
                    loff_t offset, ssize_t len)
 {
     unsigned int max_blocks;
     int ret = 0, ret2 = 0, ret3 = 0;
     struct ext4_map_blocks map;
     unsigned int blkbits = inode->i_blkbits;
     unsigned int credits = 0;
 
     map.m_lblk = offset >> blkbits;
     max_blocks = EXT4_MAX_BLOCKS(len, offset, blkbits);
 
     if (!handle) {
         /*
          * credits to insert 1 extent into extent tree
          */
         credits = ext4_chunk_trans_blocks(inode, max_blocks);
     }
     while (ret >= 0 && ret < max_blocks) {
         map.m_lblk += ret;
         map.m_len = (max_blocks -= ret);
         if (credits) {
             handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
                             credits);
             if (IS_ERR(handle)) {
                 ret = PTR_ERR(handle);
                 break;
             }
         }
         ret = ext4_map_blocks(handle, inode, &map,
                       EXT4_GET_BLOCKS_IO_CONVERT_EXT);
         if (ret <= 0)
             ext4_warning(inode->i_sb,
                      "inode #%lu: block %u: len %u: "
                      "ext4_ext_map_blocks returned %d",
                      inode->i_ino, map.m_lblk,
                      map.m_len, ret);
         ret2 = ext4_mark_inode_dirty(handle, inode);
         if (credits) {
             ret3 = ext4_journal_stop(handle);
             if (unlikely(ret3))
                 ret2 = ret3;
         }
 
         if (ret <= 0 || ret2)
             break;
     }
     return ret > 0 ? ret2 : ret;
 }
 
 int ext4_convert_unwritten_io_end_vec(handle_t *handle, ext4_io_end_t *io_end)
 {
     int ret = 0, err = 0;
     struct ext4_io_end_vec *io_end_vec;
 
     /*
      * This is somewhat ugly but the idea is clear: When transaction is
      * reserved, everything goes into it. Otherwise we rather start several
      * smaller transactions for conversion of each extent separately.
      */
     if (handle) {
         handle = ext4_journal_start_reserved(handle,
                              EXT4_HT_EXT_CONVERT);
         if (IS_ERR(handle))
             return PTR_ERR(handle);
     }
 
     list_for_each_entry(io_end_vec, &io_end->list_vec, list) {
         ret = ext4_convert_unwritten_extents(handle, io_end->inode,
                              io_end_vec->offset,
                              io_end_vec->size);
         if (ret)
             break;
     }
 
     if (handle)
         err = ext4_journal_stop(handle);
 
     return ret < 0 ? ret : err;
 }
 
 static int ext4_iomap_xattr_fiemap(struct inode *inode, struct iomap *iomap)
 {
     __u64 physical = 0;
     __u64 length = 0;
     int blockbits = inode->i_sb->s_blocksize_bits;
     int error = 0;
     u16 iomap_type;
 
     /* in-inode? */
     if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
         struct ext4_iloc iloc;
         int offset; /* offset of xattr in inode */
 
         error = ext4_get_inode_loc(inode, &iloc);
         if (error)
             return error;
         physical = (__u64)iloc.bh->b_blocknr << blockbits;
         offset = EXT4_GOOD_OLD_INODE_SIZE +
                 EXT4_I(inode)->i_extra_isize;
         physical += offset;
         length = EXT4_SB(inode->i_sb)->s_inode_size - offset;
         brelse(iloc.bh);
         iomap_type = IOMAP_INLINE;
     } else if (EXT4_I(inode)->i_file_acl) { /* external block */
         physical = (__u64)EXT4_I(inode)->i_file_acl << blockbits;
         length = inode->i_sb->s_blocksize;
         iomap_type = IOMAP_MAPPED;
     } else {
         /* no in-inode or external block for xattr, so return -ENOENT */
         error = -ENOENT;
         goto out;
     }
 
     iomap->addr = physical;
     iomap->offset = 0;
     iomap->length = length;
     iomap->type = iomap_type;
     iomap->flags = 0;
 out:
     return error;
 }
 
 static int ext4_iomap_xattr_begin(struct inode *inode, loff_t offset,
                   loff_t length, unsigned flags,
                   struct iomap *iomap, struct iomap *srcmap)
 {
     int error;
 
     error = ext4_iomap_xattr_fiemap(inode, iomap);
     if (error == 0 && (offset >= iomap->length))
         error = -ENOENT;
     return error;
 }
 
 static const struct iomap_ops ext4_iomap_xattr_ops = {
     .iomap_begin        = ext4_iomap_xattr_begin,
 };
 
 static int ext4_fiemap_check_ranges(struct inode *inode, u64 start, u64 *len)
 {
     u64 maxbytes;
 
     if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         maxbytes = inode->i_sb->s_maxbytes;
     else
         maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 
     if (*len == 0)
         return -EINVAL;
     if (start > maxbytes)
         return -EFBIG;
 
     /*
      * Shrink request scope to what the fs can actually handle.
      */
     if (*len > maxbytes || (maxbytes - *len) < start)
         *len = maxbytes - start;
     return 0;
 }
 
 int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
         u64 start, u64 len)
 {
     int error = 0;
 
     if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
         error = ext4_ext_precache(inode);
         if (error)
             return error;
         fieinfo->fi_flags &= ~FIEMAP_FLAG_CACHE;
     }
 
     /*
      * For bitmap files the maximum size limit could be smaller than
      * s_maxbytes, so check len here manually instead of just relying on the
      * generic check.
      */
     error = ext4_fiemap_check_ranges(inode, start, &len);
     if (error)
         return error;
 
     if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
         fieinfo->fi_flags &= ~FIEMAP_FLAG_XATTR;
         return iomap_fiemap(inode, fieinfo, start, len,
                     &ext4_iomap_xattr_ops);
     }
 
     return iomap_fiemap(inode, fieinfo, start, len, &ext4_iomap_report_ops);
 }
 
 int ext4_get_es_cache(struct inode *inode, struct fiemap_extent_info *fieinfo,
               __u64 start, __u64 len)
 {
     ext4_lblk_t start_blk, len_blks;
     __u64 last_blk;
     int error = 0;
 
     if (ext4_has_inline_data(inode)) {
         int has_inline;
 
         down_read(&EXT4_I(inode)->xattr_sem);
         has_inline = ext4_has_inline_data(inode);
         up_read(&EXT4_I(inode)->xattr_sem);
         if (has_inline)
             return 0;
     }
 
     if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
         error = ext4_ext_precache(inode);
         if (error)
             return error;
         fieinfo->fi_flags &= ~FIEMAP_FLAG_CACHE;
     }
 
     error = fiemap_prep(inode, fieinfo, start, &len, 0);
     if (error)
         return error;
 
     error = ext4_fiemap_check_ranges(inode, start, &len);
     if (error)
         return error;
 
     start_blk = start >> inode->i_sb->s_blocksize_bits;
     last_blk = (start + len - 1) >> inode->i_sb->s_blocksize_bits;
     if (last_blk >= EXT_MAX_BLOCKS)
         last_blk = EXT_MAX_BLOCKS-1;
     len_blks = ((ext4_lblk_t) last_blk) - start_blk + 1;
 
     /*
      * Walk the extent tree gathering extent information
      * and pushing extents back to the user.
      */
     return ext4_fill_es_cache_info(inode, start_blk, len_blks, fieinfo);
 }
 
 /*
  * ext4_ext_shift_path_extents:
  * Shift the extents of a path structure lying between path[depth].p_ext
  * and EXT_LAST_EXTENT(path[depth].p_hdr), by @shift blocks. @SHIFT tells
  * if it is right shift or left shift operation.
  */
 static int
 ext4_ext_shift_path_extents(struct ext4_ext_path *path, ext4_lblk_t shift,
                 struct inode *inode, handle_t *handle,
                 enum SHIFT_DIRECTION SHIFT)
 {
     int depth, err = 0;
     struct ext4_extent *ex_start, *ex_last;
     bool update = false;
     int credits, restart_credits;
     depth = path->p_depth;
 
     while (depth >= 0) {
         if (depth == path->p_depth) {
             ex_start = path[depth].p_ext;
             if (!ex_start)
                 return -EFSCORRUPTED;
 
             ex_last = EXT_LAST_EXTENT(path[depth].p_hdr);
             /* leaf + sb + inode */
             credits = 3;
             if (ex_start == EXT_FIRST_EXTENT(path[depth].p_hdr)) {
                 update = true;
                 /* extent tree + sb + inode */
                 credits = depth + 2;
             }
 
             restart_credits = ext4_writepage_trans_blocks(inode);
             err = ext4_datasem_ensure_credits(handle, inode, credits,
                     restart_credits, 0);
             if (err) {
                 if (err > 0)
                     err = -EAGAIN;
                 goto out;
             }
 
             err = ext4_ext_get_access(handle, inode, path + depth);
             if (err)
                 goto out;
 
             while (ex_start <= ex_last) {
                 if (SHIFT == SHIFT_LEFT) {
                     le32_add_cpu(&ex_start->ee_block,
                         -shift);
                     /* Try to merge to the left. */
                     if ((ex_start >
                         EXT_FIRST_EXTENT(path[depth].p_hdr))
                         &&
                         ext4_ext_try_to_merge_right(inode,
                         path, ex_start - 1))
                         ex_last--;
                     else
                         ex_start++;
                 } else {
                     le32_add_cpu(&ex_last->ee_block, shift);
                     ext4_ext_try_to_merge_right(inode, path,
                         ex_last);
                     ex_last--;
                 }
             }
             err = ext4_ext_dirty(handle, inode, path + depth);
             if (err)
                 goto out;
 
             if (--depth < 0 || !update)
                 break;
         }
 
         /* Update index too */
         err = ext4_ext_get_access(handle, inode, path + depth);
         if (err)
             goto out;
 
         if (SHIFT == SHIFT_LEFT)
             le32_add_cpu(&path[depth].p_idx->ei_block, -shift);
         else
             le32_add_cpu(&path[depth].p_idx->ei_block, shift);
         err = ext4_ext_dirty(handle, inode, path + depth);
         if (err)
             goto out;
 
         /* we are done if current index is not a starting index */
         if (path[depth].p_idx != EXT_FIRST_INDEX(path[depth].p_hdr))
             break;
 
         depth--;
     }
 
 out:
     return err;
 }
 
 /*
  * ext4_ext_shift_extents:
  * All the extents which lies in the range from @start to the last allocated
  * block for the @inode are shifted either towards left or right (depending
  * upon @SHIFT) by @shift blocks.
  * On success, 0 is returned, error otherwise.
  */
 static int
 ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
                ext4_lblk_t start, ext4_lblk_t shift,
                enum SHIFT_DIRECTION SHIFT)
 {
     struct ext4_ext_path *path;
     int ret = 0, depth;
     struct ext4_extent *extent;
     ext4_lblk_t stop, *iterator, ex_start, ex_end;
     ext4_lblk_t tmp = EXT_MAX_BLOCKS;
 
     /* Let path point to the last extent */
     path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL,
                 EXT4_EX_NOCACHE);
     if (IS_ERR(path))
         return PTR_ERR(path);
 
     depth = path->p_depth;
     extent = path[depth].p_ext;
     if (!extent)
         goto out;
 
     stop = le32_to_cpu(extent->ee_block);
 
        /*
     * For left shifts, make sure the hole on the left is big enough to
     * accommodate the shift.  For right shifts, make sure the last extent
     * won't be shifted beyond EXT_MAX_BLOCKS.
     */
     if (SHIFT == SHIFT_LEFT) {
         path = ext4_find_extent(inode, start - 1, &path,
                     EXT4_EX_NOCACHE);
         if (IS_ERR(path))
             return PTR_ERR(path);
         depth = path->p_depth;
         extent =  path[depth].p_ext;
         if (extent) {
             ex_start = le32_to_cpu(extent->ee_block);
             ex_end = le32_to_cpu(extent->ee_block) +
                 ext4_ext_get_actual_len(extent);
         } else {
             ex_start = 0;
             ex_end = 0;
         }
 
         if ((start == ex_start && shift > ex_start) ||
             (shift > start - ex_end)) {
             ret = -EINVAL;
             goto out;
         }
     } else {
         if (shift > EXT_MAX_BLOCKS -
             (stop + ext4_ext_get_actual_len(extent))) {
             ret = -EINVAL;
             goto out;
         }
     }
 
     /*
      * In case of left shift, iterator points to start and it is increased
      * till we reach stop. In case of right shift, iterator points to stop
      * and it is decreased till we reach start.
      */
 again:
     if (SHIFT == SHIFT_LEFT)
         iterator = &start;
     else
         iterator = &stop;
 
     if (tmp != EXT_MAX_BLOCKS)
         *iterator = tmp;
 
     /*
      * Its safe to start updating extents.  Start and stop are unsigned, so
      * in case of right shift if extent with 0 block is reached, iterator
      * becomes NULL to indicate the end of the loop.
      */
     while (iterator && start <= stop) {
         path = ext4_find_extent(inode, *iterator, &path,
                     EXT4_EX_NOCACHE);
         if (IS_ERR(path))
             return PTR_ERR(path);
         depth = path->p_depth;
         extent = path[depth].p_ext;
         if (!extent) {
             EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
                      (unsigned long) *iterator);
             return -EFSCORRUPTED;
         }
         if (SHIFT == SHIFT_LEFT && *iterator >
             le32_to_cpu(extent->ee_block)) {
             /* Hole, move to the next extent */
             if (extent < EXT_LAST_EXTENT(path[depth].p_hdr)) {
                 path[depth].p_ext++;
             } else {
                 *iterator = ext4_ext_next_allocated_block(path);
                 continue;
             }
         }
 
         tmp = *iterator;
         if (SHIFT == SHIFT_LEFT) {
             extent = EXT_LAST_EXTENT(path[depth].p_hdr);
             *iterator = le32_to_cpu(extent->ee_block) +
                     ext4_ext_get_actual_len(extent);
         } else {
             extent = EXT_FIRST_EXTENT(path[depth].p_hdr);
             if (le32_to_cpu(extent->ee_block) > 0)
                 *iterator = le32_to_cpu(extent->ee_block) - 1;
             else
                 /* Beginning is reached, end of the loop */
                 iterator = NULL;
             /* Update path extent in case we need to stop */
             while (le32_to_cpu(extent->ee_block) < start)
                 extent++;
             path[depth].p_ext = extent;
         }
         ret = ext4_ext_shift_path_extents(path, shift, inode,
                 handle, SHIFT);
         /* iterator can be NULL which means we should break */
         if (ret == -EAGAIN)
             goto again;
         if (ret)
             break;
     }
 out:
     ext4_ext_drop_refs(path);
     kfree(path);
     return ret;
 }
 
 /*
  * ext4_collapse_range:
  * This implements the fallocate's collapse range functionality for ext4
  * Returns: 0 and non-zero on error.
  */
 static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
 {
     struct inode *inode = file_inode(file);
     struct super_block *sb = inode->i_sb;
     struct address_space *mapping = inode->i_mapping;
     ext4_lblk_t punch_start, punch_stop;
     handle_t *handle;
     unsigned int credits;
     loff_t new_size, ioffset;
     int ret;
 
     /*
      * We need to test this early because xfstests assumes that a
      * collapse range of (0, 1) will return EOPNOTSUPP if the file
      * system does not support collapse range.
      */
     if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         return -EOPNOTSUPP;
 
     /* Collapse range works only on fs cluster size aligned regions. */
     if (!IS_ALIGNED(offset | len, EXT4_CLUSTER_SIZE(sb)))
         return -EINVAL;
 
     trace_ext4_collapse_range(inode, offset, len);
 
     punch_start = offset >> EXT4_BLOCK_SIZE_BITS(sb);
     punch_stop = (offset + len) >> EXT4_BLOCK_SIZE_BITS(sb);
 
     /* Call ext4_force_commit to flush all data in case of data=journal. */
     if (ext4_should_journal_data(inode)) {
         ret = ext4_force_commit(inode->i_sb);
         if (ret)
             return ret;
     }
 
     inode_lock(inode);
     /*
      * There is no need to overlap collapse range with EOF, in which case
      * it is effectively a truncate operation
      */
     if (offset + len >= inode->i_size) {
         ret = -EINVAL;
         goto out_mutex;
     }
 
     /* Currently just for extent based files */
     if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
         ret = -EOPNOTSUPP;
         goto out_mutex;
     }
 
     /* Wait for existing dio to complete */
     inode_dio_wait(inode);
 
     ret = file_modified(file);
     if (ret)
         goto out_mutex;
 
     /*
      * Prevent page faults from reinstantiating pages we have released from
      * page cache.
      */
     filemap_invalidate_lock(mapping);
 
     ret = ext4_break_layouts(inode);
     if (ret)
         goto out_mmap;
 
     /*
      * Need to round down offset to be aligned with page size boundary
      * for page size > block size.
      */
     ioffset = round_down(offset, PAGE_SIZE);
     /*
      * Write tail of the last page before removed range since it will get
      * removed from the page cache below.
      */
     ret = filemap_write_and_wait_range(mapping, ioffset, offset);
     if (ret)
         goto out_mmap;
     /*
      * Write data that will be shifted to preserve them when discarding
      * page cache below. We are also protected from pages becoming dirty
      * by i_rwsem and invalidate_lock.
      */
     ret = filemap_write_and_wait_range(mapping, offset + len,
                        LLONG_MAX);
     if (ret)
         goto out_mmap;
     truncate_pagecache(inode, ioffset);
 
     credits = ext4_writepage_trans_blocks(inode);
     handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         goto out_mmap;
     }
     ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_FALLOC_RANGE, handle);
 
     down_write(&EXT4_I(inode)->i_data_sem);
     ext4_discard_preallocations(inode, 0);
 
     ret = ext4_es_remove_extent(inode, punch_start,
                     EXT_MAX_BLOCKS - punch_start);
     if (ret) {
         up_write(&EXT4_I(inode)->i_data_sem);
         goto out_stop;
     }
 
     ret = ext4_ext_remove_space(inode, punch_start, punch_stop - 1);
     if (ret) {
         up_write(&EXT4_I(inode)->i_data_sem);
         goto out_stop;
     }
     ext4_discard_preallocations(inode, 0);
 
     ret = ext4_ext_shift_extents(inode, handle, punch_stop,
                      punch_stop - punch_start, SHIFT_LEFT);
     if (ret) {
         up_write(&EXT4_I(inode)->i_data_sem);
         goto out_stop;
     }
 
     new_size = inode->i_size - len;
     i_size_write(inode, new_size);
     EXT4_I(inode)->i_disksize = new_size;
 
     up_write(&EXT4_I(inode)->i_data_sem);
     if (IS_SYNC(inode))
         ext4_handle_sync(handle);
     inode->i_mtime = inode->i_ctime = current_time(inode);
     ret = ext4_mark_inode_dirty(handle, inode);
     ext4_update_inode_fsync_trans(handle, inode, 1);
 
 out_stop:
     ext4_journal_stop(handle);
 out_mmap:
     filemap_invalidate_unlock(mapping);
 out_mutex:
     inode_unlock(inode);
     return ret;
 }
 
 /*
  * ext4_insert_range:
  * This function implements the FALLOC_FL_INSERT_RANGE flag of fallocate.
  * The data blocks starting from @offset to the EOF are shifted by @len
  * towards right to create a hole in the @inode. Inode size is increased
  * by len bytes.
  * Returns 0 on success, error otherwise.
  */
 static int ext4_insert_range(struct file *file, loff_t offset, loff_t len)
 {
     struct inode *inode = file_inode(file);
     struct super_block *sb = inode->i_sb;
     struct address_space *mapping = inode->i_mapping;
     handle_t *handle;
     struct ext4_ext_path *path;
     struct ext4_extent *extent;
     ext4_lblk_t offset_lblk, len_lblk, ee_start_lblk = 0;
     unsigned int credits, ee_len;
     int ret = 0, depth, split_flag = 0;
     loff_t ioffset;
 
     /*
      * We need to test this early because xfstests assumes that an
      * insert range of (0, 1) will return EOPNOTSUPP if the file
      * system does not support insert range.
      */
     if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         return -EOPNOTSUPP;
 
     /* Insert range works only on fs cluster size aligned regions. */
     if (!IS_ALIGNED(offset | len, EXT4_CLUSTER_SIZE(sb)))
         return -EINVAL;
 
     trace_ext4_insert_range(inode, offset, len);
 
     offset_lblk = offset >> EXT4_BLOCK_SIZE_BITS(sb);
     len_lblk = len >> EXT4_BLOCK_SIZE_BITS(sb);
 
     /* Call ext4_force_commit to flush all data in case of data=journal */
     if (ext4_should_journal_data(inode)) {
         ret = ext4_force_commit(inode->i_sb);
         if (ret)
             return ret;
     }
 
     inode_lock(inode);
     /* Currently just for extent based files */
     if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
         ret = -EOPNOTSUPP;
         goto out_mutex;
     }
 
     /* Check whether the maximum file size would be exceeded */
     if (len > inode->i_sb->s_maxbytes - inode->i_size) {
         ret = -EFBIG;
         goto out_mutex;
     }
 
     /* Offset must be less than i_size */
     if (offset >= inode->i_size) {
         ret = -EINVAL;
         goto out_mutex;
     }
 
     /* Wait for existing dio to complete */
     inode_dio_wait(inode);
 
     ret = file_modified(file);
     if (ret)
         goto out_mutex;
 
     /*
      * Prevent page faults from reinstantiating pages we have released from
      * page cache.
      */
     filemap_invalidate_lock(mapping);
 
     ret = ext4_break_layouts(inode);
     if (ret)
         goto out_mmap;
 
     /*
      * Need to round down to align start offset to page size boundary
      * for page size > block size.
      */
     ioffset = round_down(offset, PAGE_SIZE);
     /* Write out all dirty pages */
     ret = filemap_write_and_wait_range(inode->i_mapping, ioffset,
             LLONG_MAX);
     if (ret)
         goto out_mmap;
     truncate_pagecache(inode, ioffset);
 
     credits = ext4_writepage_trans_blocks(inode);
     handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         goto out_mmap;
     }
     ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_FALLOC_RANGE, handle);
 
     /* Expand file to avoid data loss if there is error while shifting */
     inode->i_size += len;
     EXT4_I(inode)->i_disksize += len;
     inode->i_mtime = inode->i_ctime = current_time(inode);
     ret = ext4_mark_inode_dirty(handle, inode);
     if (ret)
         goto out_stop;
 
     down_write(&EXT4_I(inode)->i_data_sem);
     ext4_discard_preallocations(inode, 0);
 
     path = ext4_find_extent(inode, offset_lblk, NULL, 0);
     if (IS_ERR(path)) {
         up_write(&EXT4_I(inode)->i_data_sem);
         goto out_stop;
     }
 
     depth = ext_depth(inode);
     extent = path[depth].p_ext;
     if (extent) {
         ee_start_lblk = le32_to_cpu(extent->ee_block);
         ee_len = ext4_ext_get_actual_len(extent);
 
         /*
          * If offset_lblk is not the starting block of extent, split
          * the extent @offset_lblk
          */
         if ((offset_lblk > ee_start_lblk) &&
                 (offset_lblk < (ee_start_lblk + ee_len))) {
             if (ext4_ext_is_unwritten(extent))
                 split_flag = EXT4_EXT_MARK_UNWRIT1 |
                     EXT4_EXT_MARK_UNWRIT2;
             ret = ext4_split_extent_at(handle, inode, &path,
                     offset_lblk, split_flag,
                     EXT4_EX_NOCACHE |
                     EXT4_GET_BLOCKS_PRE_IO |
                     EXT4_GET_BLOCKS_METADATA_NOFAIL);
         }
 
         ext4_ext_drop_refs(path);
         kfree(path);
         if (ret < 0) {
             up_write(&EXT4_I(inode)->i_data_sem);
             goto out_stop;
         }
     } else {
         ext4_ext_drop_refs(path);
         kfree(path);
     }
 
     ret = ext4_es_remove_extent(inode, offset_lblk,
             EXT_MAX_BLOCKS - offset_lblk);
     if (ret) {
         up_write(&EXT4_I(inode)->i_data_sem);
         goto out_stop;
     }
 
     /*
      * if offset_lblk lies in a hole which is at start of file, use
      * ee_start_lblk to shift extents
      */
     ret = ext4_ext_shift_extents(inode, handle,
         ee_start_lblk > offset_lblk ? ee_start_lblk : offset_lblk,
         len_lblk, SHIFT_RIGHT);
 
     up_write(&EXT4_I(inode)->i_data_sem);
     if (IS_SYNC(inode))
         ext4_handle_sync(handle);
     if (ret >= 0)
         ext4_update_inode_fsync_trans(handle, inode, 1);
 
 out_stop:
     ext4_journal_stop(handle);
 out_mmap:
     filemap_invalidate_unlock(mapping);
 out_mutex:
     inode_unlock(inode);
     return ret;
 }
 
 /**
  * ext4_swap_extents() - Swap extents between two inodes
  * @handle: handle for this transaction
  * @inode1: First inode
  * @inode2: Second inode
  * @lblk1:  Start block for first inode
  * @lblk2:  Start block for second inode
  * @count:  Number of blocks to swap
  * @unwritten: Mark second inode's extents as unwritten after swap
  * @erp:    Pointer to save error value
  *
  * This helper routine does exactly what is promise "swap extents". All other
  * stuff such as page-cache locking consistency, bh mapping consistency or
  * extent's data copying must be performed by caller.
  * Locking:
  *      i_rwsem is held for both inodes
  *      i_data_sem is locked for write for both inodes
  * Assumptions:
  *      All pages from requested range are locked for both inodes
  */
 int
 ext4_swap_extents(handle_t *handle, struct inode *inode1,
           struct inode *inode2, ext4_lblk_t lblk1, ext4_lblk_t lblk2,
           ext4_lblk_t count, int unwritten, int *erp)
 {
     struct ext4_ext_path *path1 = NULL;
     struct ext4_ext_path *path2 = NULL;
     int replaced_count = 0;
 
     BUG_ON(!rwsem_is_locked(&EXT4_I(inode1)->i_data_sem));
     BUG_ON(!rwsem_is_locked(&EXT4_I(inode2)->i_data_sem));
     BUG_ON(!inode_is_locked(inode1));
     BUG_ON(!inode_is_locked(inode2));
 
     *erp = ext4_es_remove_extent(inode1, lblk1, count);
     if (unlikely(*erp))
         return 0;
     *erp = ext4_es_remove_extent(inode2, lblk2, count);
     if (unlikely(*erp))
         return 0;
 
     while (count) {
         struct ext4_extent *ex1, *ex2, tmp_ex;
         ext4_lblk_t e1_blk, e2_blk;
         int e1_len, e2_len, len;
         int split = 0;
 
         path1 = ext4_find_extent(inode1, lblk1, NULL, EXT4_EX_NOCACHE);
         if (IS_ERR(path1)) {
             *erp = PTR_ERR(path1);
             path1 = NULL;
         finish:
             count = 0;
             goto repeat;
         }
         path2 = ext4_find_extent(inode2, lblk2, NULL, EXT4_EX_NOCACHE);
         if (IS_ERR(path2)) {
             *erp = PTR_ERR(path2);
             path2 = NULL;
             goto finish;
         }
         ex1 = path1[path1->p_depth].p_ext;
         ex2 = path2[path2->p_depth].p_ext;
         /* Do we have something to swap ? */
         if (unlikely(!ex2 || !ex1))
             goto finish;
 
         e1_blk = le32_to_cpu(ex1->ee_block);
         e2_blk = le32_to_cpu(ex2->ee_block);
         e1_len = ext4_ext_get_actual_len(ex1);
         e2_len = ext4_ext_get_actual_len(ex2);
 
         /* Hole handling */
         if (!in_range(lblk1, e1_blk, e1_len) ||
             !in_range(lblk2, e2_blk, e2_len)) {
             ext4_lblk_t next1, next2;
 
             /* if hole after extent, then go to next extent */
             next1 = ext4_ext_next_allocated_block(path1);
             next2 = ext4_ext_next_allocated_block(path2);
             /* If hole before extent, then shift to that extent */
             if (e1_blk > lblk1)
                 next1 = e1_blk;
             if (e2_blk > lblk2)
                 next2 = e2_blk;
             /* Do we have something to swap */
             if (next1 == EXT_MAX_BLOCKS || next2 == EXT_MAX_BLOCKS)
                 goto finish;
             /* Move to the rightest boundary */
             len = next1 - lblk1;
             if (len < next2 - lblk2)
                 len = next2 - lblk2;
             if (len > count)
                 len = count;
             lblk1 += len;
             lblk2 += len;
             count -= len;
             goto repeat;
         }
 
         /* Prepare left boundary */
         if (e1_blk < lblk1) {
             split = 1;
             *erp = ext4_force_split_extent_at(handle, inode1,
                         &path1, lblk1, 0);
             if (unlikely(*erp))
                 goto finish;
         }
         if (e2_blk < lblk2) {
             split = 1;
             *erp = ext4_force_split_extent_at(handle, inode2,
                         &path2,  lblk2, 0);
             if (unlikely(*erp))
                 goto finish;
         }
         /* ext4_split_extent_at() may result in leaf extent split,
          * path must to be revalidated. */
         if (split)
             goto repeat;
 
         /* Prepare right boundary */
         len = count;
         if (len > e1_blk + e1_len - lblk1)
             len = e1_blk + e1_len - lblk1;
         if (len > e2_blk + e2_len - lblk2)
             len = e2_blk + e2_len - lblk2;
 
         if (len != e1_len) {
             split = 1;
             *erp = ext4_force_split_extent_at(handle, inode1,
                         &path1, lblk1 + len, 0);
             if (unlikely(*erp))
                 goto finish;
         }
         if (len != e2_len) {
             split = 1;
             *erp = ext4_force_split_extent_at(handle, inode2,
                         &path2, lblk2 + len, 0);
             if (*erp)
                 goto finish;
         }
         /* ext4_split_extent_at() may result in leaf extent split,
          * path must to be revalidated. */
         if (split)
             goto repeat;
 
         BUG_ON(e2_len != e1_len);
         *erp = ext4_ext_get_access(handle, inode1, path1 + path1->p_depth);
         if (unlikely(*erp))
             goto finish;
         *erp = ext4_ext_get_access(handle, inode2, path2 + path2->p_depth);
         if (unlikely(*erp))
             goto finish;
 
         /* Both extents are fully inside boundaries. Swap it now */
         tmp_ex = *ex1;
         ext4_ext_store_pblock(ex1, ext4_ext_pblock(ex2));
         ext4_ext_store_pblock(ex2, ext4_ext_pblock(&tmp_ex));
         ex1->ee_len = cpu_to_le16(e2_len);
         ex2->ee_len = cpu_to_le16(e1_len);
         if (unwritten)
             ext4_ext_mark_unwritten(ex2);
         if (ext4_ext_is_unwritten(&tmp_ex))
             ext4_ext_mark_unwritten(ex1);
 
         ext4_ext_try_to_merge(handle, inode2, path2, ex2);
         ext4_ext_try_to_merge(handle, inode1, path1, ex1);
         *erp = ext4_ext_dirty(handle, inode2, path2 +
                       path2->p_depth);
         if (unlikely(*erp))
             goto finish;
         *erp = ext4_ext_dirty(handle, inode1, path1 +
                       path1->p_depth);
         /*
          * Looks scarry ah..? second inode already points to new blocks,
          * and it was successfully dirtied. But luckily error may happen
          * only due to journal error, so full transaction will be
          * aborted anyway.
          */
         if (unlikely(*erp))
             goto finish;
         lblk1 += len;
         lblk2 += len;
         replaced_count += len;
         count -= len;
 
     repeat:
         ext4_ext_drop_refs(path1);
         kfree(path1);
         ext4_ext_drop_refs(path2);
         kfree(path2);
         path1 = path2 = NULL;
     }
     return replaced_count;
 }
 
 /*
  * ext4_clu_mapped - determine whether any block in a logical cluster has
  *                   been mapped to a physical cluster
  *
  * @inode - file containing the logical cluster
  * @lclu - logical cluster of interest
  *
  * Returns 1 if any block in the logical cluster is mapped, signifying
  * that a physical cluster has been allocated for it.  Otherwise,
  * returns 0.  Can also return negative error codes.  Derived from
  * ext4_ext_map_blocks().
  */
 int ext4_clu_mapped(struct inode *inode, ext4_lblk_t lclu)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     struct ext4_ext_path *path;
     int depth, mapped = 0, err = 0;
     struct ext4_extent *extent;
     ext4_lblk_t first_lblk, first_lclu, last_lclu;
 
     /* search for the extent closest to the first block in the cluster */
     path = ext4_find_extent(inode, EXT4_C2B(sbi, lclu), NULL, 0);
     if (IS_ERR(path)) {
         err = PTR_ERR(path);
         path = NULL;
         goto out;
     }
 
     depth = ext_depth(inode);
 
     /*
      * A consistent leaf must not be empty.  This situation is possible,
      * though, _during_ tree modification, and it's why an assert can't
      * be put in ext4_find_extent().
      */
     if (unlikely(path[depth].p_ext == NULL && depth != 0)) {
         EXT4_ERROR_INODE(inode,
             "bad extent address - lblock: %lu, depth: %d, pblock: %lld",
                  (unsigned long) EXT4_C2B(sbi, lclu),
                  depth, path[depth].p_block);
         err = -EFSCORRUPTED;
         goto out;
     }
 
     extent = path[depth].p_ext;
 
     /* can't be mapped if the extent tree is empty */
     if (extent == NULL)
         goto out;
 
     first_lblk = le32_to_cpu(extent->ee_block);
     first_lclu = EXT4_B2C(sbi, first_lblk);
 
     /*
      * Three possible outcomes at this point - found extent spanning
      * the target cluster, to the left of the target cluster, or to the
      * right of the target cluster.  The first two cases are handled here.
      * The last case indicates the target cluster is not mapped.
      */
     if (lclu >= first_lclu) {
         last_lclu = EXT4_B2C(sbi, first_lblk +
                      ext4_ext_get_actual_len(extent) - 1);
         if (lclu <= last_lclu) {
             mapped = 1;
         } else {
             first_lblk = ext4_ext_next_allocated_block(path);
             first_lclu = EXT4_B2C(sbi, first_lblk);
             if (lclu == first_lclu)
                 mapped = 1;
         }
     }
 
 out:
     ext4_ext_drop_refs(path);
     kfree(path);
 
     return err ? err : mapped;
 }
 
 /*
  * Updates physical block address and unwritten status of extent
  * starting at lblk start and of len. If such an extent doesn't exist,
  * this function splits the extent tree appropriately to create an
  * extent like this.  This function is called in the fast commit
  * replay path.  Returns 0 on success and error on failure.
  */
 int ext4_ext_replay_update_ex(struct inode *inode, ext4_lblk_t start,
                   int len, int unwritten, ext4_fsblk_t pblk)
 {
     struct ext4_ext_path *path = NULL, *ppath;
     struct ext4_extent *ex;
     int ret;
 
     path = ext4_find_extent(inode, start, NULL, 0);
     if (IS_ERR(path))
         return PTR_ERR(path);
     ex = path[path->p_depth].p_ext;
     if (!ex) {
         ret = -EFSCORRUPTED;
         goto out;
     }
 
     if (le32_to_cpu(ex->ee_block) != start ||
         ext4_ext_get_actual_len(ex) != len) {
         /* We need to split this extent to match our extent first */
         ppath = path;
         down_write(&EXT4_I(inode)->i_data_sem);
         ret = ext4_force_split_extent_at(NULL, inode, &ppath, start, 1);
         up_write(&EXT4_I(inode)->i_data_sem);
         if (ret)
             goto out;
         kfree(path);
         path = ext4_find_extent(inode, start, NULL, 0);
         if (IS_ERR(path))
             return -1;
         ppath = path;
         ex = path[path->p_depth].p_ext;
         WARN_ON(le32_to_cpu(ex->ee_block) != start);
         if (ext4_ext_get_actual_len(ex) != len) {
             down_write(&EXT4_I(inode)->i_data_sem);
             ret = ext4_force_split_extent_at(NULL, inode, &ppath,
                              start + len, 1);
             up_write(&EXT4_I(inode)->i_data_sem);
             if (ret)
                 goto out;
             kfree(path);
             path = ext4_find_extent(inode, start, NULL, 0);
             if (IS_ERR(path))
                 return -EINVAL;
             ex = path[path->p_depth].p_ext;
         }
     }
     if (unwritten)
         ext4_ext_mark_unwritten(ex);
     else
         ext4_ext_mark_initialized(ex);
     ext4_ext_store_pblock(ex, pblk);
     down_write(&EXT4_I(inode)->i_data_sem);
     ret = ext4_ext_dirty(NULL, inode, &path[path->p_depth]);
     up_write(&EXT4_I(inode)->i_data_sem);
 out:
     ext4_ext_drop_refs(path);
     kfree(path);
     ext4_mark_inode_dirty(NULL, inode);
     return ret;
 }
 
 /* Try to shrink the extent tree */
 void ext4_ext_replay_shrink_inode(struct inode *inode, ext4_lblk_t end)
 {
     struct ext4_ext_path *path = NULL;
     struct ext4_extent *ex;
     ext4_lblk_t old_cur, cur = 0;
 
     while (cur < end) {
         path = ext4_find_extent(inode, cur, NULL, 0);
         if (IS_ERR(path))
             return;
         ex = path[path->p_depth].p_ext;
         if (!ex) {
             ext4_ext_drop_refs(path);
             kfree(path);
             ext4_mark_inode_dirty(NULL, inode);
             return;
         }
         old_cur = cur;
         cur = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
         if (cur <= old_cur)
             cur = old_cur + 1;
         ext4_ext_try_to_merge(NULL, inode, path, ex);
         down_write(&EXT4_I(inode)->i_data_sem);
         ext4_ext_dirty(NULL, inode, &path[path->p_depth]);
         up_write(&EXT4_I(inode)->i_data_sem);
         ext4_mark_inode_dirty(NULL, inode);
         ext4_ext_drop_refs(path);
         kfree(path);
     }
 }
 
 /* Check if *cur is a hole and if it is, skip it */
 static int skip_hole(struct inode *inode, ext4_lblk_t *cur)
 {
     int ret;
     struct ext4_map_blocks map;
 
     map.m_lblk = *cur;
     map.m_len = ((inode->i_size) >> inode->i_sb->s_blocksize_bits) - *cur;
 
     ret = ext4_map_blocks(NULL, inode, &map, 0);
     if (ret < 0)
         return ret;
     if (ret != 0)
         return 0;
     *cur = *cur + map.m_len;
     return 0;
 }
 
 /* Count number of blocks used by this inode and update i_blocks */
 int ext4_ext_replay_set_iblocks(struct inode *inode)
 {
     struct ext4_ext_path *path = NULL, *path2 = NULL;
     struct ext4_extent *ex;
     ext4_lblk_t cur = 0, end;
     int numblks = 0, i, ret = 0;
     ext4_fsblk_t cmp1, cmp2;
     struct ext4_map_blocks map;
 
     /* Determin the size of the file first */
     path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL,
                     EXT4_EX_NOCACHE);
     if (IS_ERR(path))
         return PTR_ERR(path);
     ex = path[path->p_depth].p_ext;
     if (!ex) {
         ext4_ext_drop_refs(path);
         kfree(path);
         goto out;
     }
     end = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
     ext4_ext_drop_refs(path);
     kfree(path);
 
     /* Count the number of data blocks */
     cur = 0;
     while (cur < end) {
         map.m_lblk = cur;
         map.m_len = end - cur;
         ret = ext4_map_blocks(NULL, inode, &map, 0);
         if (ret < 0)
             break;
         if (ret > 0)
             numblks += ret;
         cur = cur + map.m_len;
     }
 
     /*
      * Count the number of extent tree blocks. We do it by looking up
      * two successive extents and determining the difference between
      * their paths. When path is different for 2 successive extents
      * we compare the blocks in the path at each level and increment
      * iblocks by total number of differences found.
      */
     cur = 0;
     ret = skip_hole(inode, &cur);
     if (ret < 0)
         goto out;
     path = ext4_find_extent(inode, cur, NULL, 0);
     if (IS_ERR(path))
         goto out;
     numblks += path->p_depth;
     ext4_ext_drop_refs(path);
     kfree(path);
     while (cur < end) {
         path = ext4_find_extent(inode, cur, NULL, 0);
         if (IS_ERR(path))
             break;
         ex = path[path->p_depth].p_ext;
         if (!ex) {
             ext4_ext_drop_refs(path);
             kfree(path);
             return 0;
         }
         cur = max(cur + 1, le32_to_cpu(ex->ee_block) +
                     ext4_ext_get_actual_len(ex));
         ret = skip_hole(inode, &cur);
         if (ret < 0) {
             ext4_ext_drop_refs(path);
             kfree(path);
             break;
         }
         path2 = ext4_find_extent(inode, cur, NULL, 0);
         if (IS_ERR(path2)) {
             ext4_ext_drop_refs(path);
             kfree(path);
             break;
         }
         for (i = 0; i <= max(path->p_depth, path2->p_depth); i++) {
             cmp1 = cmp2 = 0;
             if (i <= path->p_depth)
                 cmp1 = path[i].p_bh ?
                     path[i].p_bh->b_blocknr : 0;
             if (i <= path2->p_depth)
                 cmp2 = path2[i].p_bh ?
                     path2[i].p_bh->b_blocknr : 0;
             if (cmp1 != cmp2 && cmp2 != 0)
                 numblks++;
         }
         ext4_ext_drop_refs(path);
         ext4_ext_drop_refs(path2);
         kfree(path);
         kfree(path2);
     }
 
 out:
     inode->i_blocks = numblks << (inode->i_sb->s_blocksize_bits - 9);
     ext4_mark_inode_dirty(NULL, inode);
     return 0;
 }
 
 int ext4_ext_clear_bb(struct inode *inode)
 {
     struct ext4_ext_path *path = NULL;
     struct ext4_extent *ex;
     ext4_lblk_t cur = 0, end;
     int j, ret = 0;
     struct ext4_map_blocks map;
 
     if (ext4_test_inode_flag(inode, EXT4_INODE_INLINE_DATA))
         return 0;
 
     /* Determin the size of the file first */
     path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL,
                     EXT4_EX_NOCACHE);
     if (IS_ERR(path))
         return PTR_ERR(path);
     ex = path[path->p_depth].p_ext;
     if (!ex) {
         ext4_ext_drop_refs(path);
         kfree(path);
         return 0;
     }
     end = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
     ext4_ext_drop_refs(path);
     kfree(path);
 
     cur = 0;
     while (cur < end) {
         map.m_lblk = cur;
         map.m_len = end - cur;
         ret = ext4_map_blocks(NULL, inode, &map, 0);
         if (ret < 0)
             break;
         if (ret > 0) {
             path = ext4_find_extent(inode, map.m_lblk, NULL, 0);
             if (!IS_ERR_OR_NULL(path)) {
                 for (j = 0; j < path->p_depth; j++) {
 
                     ext4_mb_mark_bb(inode->i_sb,
                             path[j].p_block, 1, 0);
                     ext4_fc_record_regions(inode->i_sb, inode->i_ino,
                             0, path[j].p_block, 1, 1);
                 }
                 ext4_ext_drop_refs(path);
                 kfree(path);
             }
             ext4_mb_mark_bb(inode->i_sb, map.m_pblk, map.m_len, 0);
             ext4_fc_record_regions(inode->i_sb, inode->i_ino,
                     map.m_lblk, map.m_pblk, map.m_len, 1);
         }
         cur = cur + map.m_len;
     }
 
     return 0;
 }