call-ext4_ext_drop_refs-from-ext4_ext_find_extent

   1 ext4: call ext4_ext_drop_refs() from ext4_ext_find_extent()
   2
   3 In nearly all of the calls to ext4_ext_find_extent() where the caller
   4 is trying to recycle the path object, ext4_ext_drop_refs() gets called
   5 to release the buffer heads before the path object gets overwritten.
   6 To simplify things for the callers, and to avoid the possibility of a
   7 memory leak, make ext4_ext_find_extent() responsible for dropping the
   8 buffers.
   9
  10 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  11 ---
  12  fs/ext4/extents.c | 11 ++++-------
  13  1 file changed, 4 insertions(+), 7 deletions(-)
  14
  15 diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
  16 index f6d8b00..62aa508 100644
  17 --- a/fs/ext4/extents.c
  18 +++ b/fs/ext4/extents.c
  19 @@ -859,8 +859,10 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
  20         eh = ext_inode_hdr(inode);
  21         depth = ext_depth(inode);
  22
  23 -       /* account possible depth increase */
  24 -       if (!path) {
  25 +       if (path)
  26 +               ext4_ext_drop_refs(path);
  27 +       else {
  28 +               /* account possible depth increase */
  29                 path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
  30                                 GFP_NOFS);
  31                 if (unlikely(!path))
  32 @@ -1348,7 +1350,6 @@ repeat:
  33                         goto out;
  34
  35                 /* refill path */
  36 -               ext4_ext_drop_refs(path);
  37                 path = ext4_ext_find_extent(inode,
  38                                     (ext4_lblk_t)le32_to_cpu(newext->ee_block),
  39                                     ppath, gb_flags);
  40 @@ -1361,7 +1362,6 @@ repeat:
  41                         goto out;
  42
  43                 /* refill path */
  44 -               ext4_ext_drop_refs(path);
  45                 path = ext4_ext_find_extent(inode,
  46                                    (ext4_lblk_t)le32_to_cpu(newext->ee_block),
  47                                     ppath, gb_flags);
  48 @@ -3325,7 +3325,6 @@ static int ext4_split_extent(handle_t *handle,
  49          * Update path is required because previous ext4_split_extent_at() may
  50          * result in split of original leaf or extent zeroout.
  51          */
  52 -       ext4_ext_drop_refs(path);
  53         path = ext4_ext_find_extent(inode, map->m_lblk, ppath, 0);
  54         if (IS_ERR(path))
  55                 return PTR_ERR(path);
  56 @@ -3724,7 +3723,6 @@ static int ext4_convert_unwritten_extents_endio(handle_t *handle,
  57                                                  EXT4_GET_BLOCKS_CONVERT);
  58                 if (err < 0)
  59                         return err;
  60 -               ext4_ext_drop_refs(path);
  61                 path = ext4_ext_find_extent(inode, map->m_lblk, ppath, 0);
  62                 if (IS_ERR(path))
  63                         return PTR_ERR(path);
  64 @@ -3953,7 +3951,6 @@ convert_initialized_extent(handle_t *handle, struct inode *inode,
  65                                 EXT4_GET_BLOCKS_CONVERT_UNWRITTEN);
  66                 if (err < 0)
  67                         return err;
  68 -               ext4_ext_drop_refs(path);
  69                 path = ext4_ext_find_extent(inode, map->m_lblk, ppath, 0);
  70                 if (IS_ERR(path))
  71                         return PTR_ERR(path);