prevent-fs-reentrant-deadlock-for-inline-data

   1 ext4: prevent fsreentrance deadlock for inline_data
   2
   3 From: Dmitry Monakhov <dmonakhov@openvz.org>
   4
   5 ext4_da_convert_inline_data_to_extent() invokes
   6 grab_cache_page_write_begin().  grab_cache_page_write_begin performs
   7 memory allocation, so fs-reentrance should be prohibited because we
   8 are inside journal transaction.
   9
  10 Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
  11 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  12 ---
  13  fs/ext4/inline.c | 11 ++++++-----
  14  1 file changed, 6 insertions(+), 5 deletions(-)
  15
  16 diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
  17 index 3ea6269..efdcede 100644
  18 --- a/fs/ext4/inline.c
  19 +++ b/fs/ext4/inline.c
  20 @@ -870,6 +870,12 @@ retry_journal:
  21                         goto out_journal;
  22         }
  23
  24 +       /*
  25 +        * We cannot recurse into the filesystem as the transaction
  26 +        * is already started.
  27 +        */
  28 +       flags |= AOP_FLAG_NOFS;
  29 +
  30         if (ret == -ENOSPC) {
  31                 ret = ext4_da_convert_inline_data_to_extent(mapping,
  32                                                             inode,
  33 @@ -882,11 +888,6 @@ retry_journal:
  34                 goto out;
  35         }
  36
  37 -       /*
  38 -        * We cannot recurse into the filesystem as the transaction
  39 -        * is already started.
  40 -        */
  41 -       flags |= AOP_FLAG_NOFS;
  42
  43         page = grab_cache_page_write_begin(mapping, 0, flags);
  44         if (!page) {