Re: [PATCH] Btrfs: fix leaf corruption after __btrfs_drop_extents

[Liu Bo <bo.li.liu@oracle.com>]

On Fri, Jun 06, 2014 at 02:02:07PM +0000, Holger Hoffstätte wrote:
> On Fri, 06 Jun 2014 14:25:58 +0800, Liu Bo wrote:
> 
> > Several reports about leaf corruption has been floating on the list, one
> > of them points to __btrfs_drop_extents(), and we find that the leaf
> > becomes corrupted after __btrfs_drop_extents(), it's really a rare case
> > but it does exist.
> 
> Out of curiosity ("..what could go wrong?" :) I applied this to 3.14.6, 
> rebooted and worked a bit on my btrfs drive - rsyncs, create & delete 
> snapshots etc. For the first time in ages I got two kernel messages:
> 
> Jun  6 09:20:56 tux kernel: BTRFS error (device sdb1): block group 
> 351872745472 has wrong amount of free space
> Jun  6 09:20:56 tux kernel: BTRFS error (device sdb1): failed to load 
> free space cache for block group 351872745472
> 
> I remounted without inode_cache & clear_cache, worked some more and so 
> far no more messages. Could the messages be related to this patch? Or am 
> I just looking at a coincidental/unrelated occurrence? Dropping the 
> snapshots correctly freed up several GBs, so I assume that extents were 
> dropped..

Well, I think they're unrelated ;)

We saw similar space cache errors from other reports, but it mainly came from a
unclean shutdown or poweroff.

-liubo

> 
> thanks
> Holger
> 
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