trigger-error-on-journal_dirty_metadata

   1 ext4: call ext4_error_inode() if jbd2_journal_dirty_metadata() fails
   2
   3 While it's true that errors can only happen if there is a bug in
   4 jbd2_journal_dirty_metadata(), if a bug does happen, we need to halt
   5 the kernel or remount the file system read-only in order to avoid
   6 further data loss.  The ext4_journal_abort_handle() function doesn't
   7 do any of this, and while it's likely that this call (since it doesn't
   8 adjust refcounts) will likely result in the file system eventually
   9 deadlocking since the current transaction will never be able to close,
  10 it's much cleaner to call let ext4's error handling system deal with
  11 this situation.
  12
  13 There's a separate bug here which is that if certain jbd2 errors
  14 errors occur and file system is mounted errors=continue, the file
  15 system will probably eventually end grind to a halt as described
  16 above.  But things have been this way in a long time, and usually when
  17 we have these sorts of errors it's pretty much a disaster --- and
  18 that's why the jbd2 layer aggressively retries memory allocations,
  19 which is the most likely cause of these jbd2 errors.
  20
  21 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  22 Cc: stable@vger.kernel.org
  23 ---
  24  fs/ext4/ext4_jbd2.c | 9 +++++++++
  25  1 file changed, 9 insertions(+)
  26
  27 diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
  28 index 17ac112..3fe29de 100644
  29 --- a/fs/ext4/ext4_jbd2.c
  30 +++ b/fs/ext4/ext4_jbd2.c
  31 @@ -259,6 +259,15 @@ int __ext4_handle_dirty_metadata(const char *where, unsigned int line,
  32                 if (WARN_ON_ONCE(err)) {
  33                         ext4_journal_abort_handle(where, line, __func__, bh,
  34                                                   handle, err);
  35 +                       ext4_error_inode(inode, where, line,
  36 +                                        bh->b_blocknr,
  37 +                                        "journal_dirty_metadata failed: "
  38 +                                        "handle type %u started at line %u, "
  39 +                                        "credits %u/%u, errcode %d",
  40 +                                        handle->h_type,
  41 +                                        handle->h_line_no,
  42 +                                        handle->h_requested_credits,
  43 +                                        handle->h_buffer_credits, err);
  44                 }
  45         } else {
  46                 if (inode)