On Mon, 2014-09-15 at 15:08 -0700, Kamal Mostafa wrote:

3.13.11.7 -stable review patch.  If anyone has any objections, please let me know.

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From: Theodore Ts'o <tytso@mit.edu>

commit 86f0afd463215fc3e58020493482faa4ac3a4d69 upstream.

If there is a failure while allocating the preallocation structure, a
number of blocks can end up getting marked in the in-memory buddy
bitmap, and then not getting released.  This can result in the
following corruption getting reported by the kernel:

EXT4-fs error (device sda3): ext4_mb_generate_buddy:758: group 1126,
12793 clusters in bitmap, 12729 in gd

In that case, we need to release the blocks using mb_free_blocks().

Tested: fs smoke test; also demonstrated that with injected errors,
	the file system is no longer getting corrupted

Google-Bug-Id: 16657874

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Kamal Mostafa <redacted>

[...]

You need to apply commit c99d1e6e83b0 ("ext4: fix BUG_ON in
mb_free_blocks()") along with this.

Ben.

-- 
Ben Hutchings
Beware of programmers who carry screwdrivers. - Leonard Brandwein