Re: [PATCH 4/4] ext4: avoid dividing by 0 in mb_update_avg_fragment_size() when block bitmap corrupt

[Jan Kara]

On Mon 18-12-23 15:43:42, Jan Kara wrote:
> On Mon 18-12-23 22:18:14, Baokun Li wrote:
> > When bb_free is not 0 but bb_fragments is 0, return directly to avoid
> > system crash due to division by zero.
> 
> How could this possibly happen? bb_fragments is the number of free space
> extents and bb_free is the number of free blocks. No free space extents =>
> no free blocks seems pretty obvious? You can see the logic in
> ext4_mb_generate_buddy()...

Oh, I see. This is probably about "bitmap corrupted case". But still both
allocation and freeing of blocks shouldn't operate on bitmaps marked as
corrupted so this should not happen?

								Honza
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR