Re: [PATCH 3.13 120/187] ext4: fix ext4_discard_allocated_blocks() if we can't allocate the pa struct

[Kamal Mostafa]

On Wed, 2014-09-17 at 12:13 +0100, Ben Hutchings wrote:
> 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.
> > 
> > ------------------
> > 
> > From: Theodore Ts'o <tytso@xxxxxxx>
> > 
> > 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@xxxxxxx>
> > Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
> [...]
> 
> You need to apply commit c99d1e6e83b0 ("ext4: fix BUG_ON in
> mb_free_blocks()") along with this.
> 
> Ben.
> 

Ok, that's now queued up for 3.13.11.7 also.  Thanks again, Ben.

 -Kamal


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