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17 May 2024, 09:02:56 UTC
Revision d288db5dc0110c8e0732d099aaf7a05e2ea0e0c8 authored by Liu Bo on 02 July 2014, 08:58:01 UTC, committed by Chris Mason on 03 July 2014, 14:04:15 UTC 
Btrfs: fix race of using total_bytes_pinned
 
This percpu counter @total_bytes_pinned is introduced to skip unnecessary
operations of 'commit transaction', it accounts for those space we may free
but are stuck in delayed refs.

And we zero out @space_info->total_bytes_pinned every transaction period so
we have a better idea of how much space we'll actually free up by committing
this transaction.  However, we do the 'zero out' part a little earlier, before
we actually unpin space, so we end up returning ENOSPC when we actually have
free space that's just unpinned from committing transaction.

xfstests/generic/074 complained then.

This fixes it by actually accounting the percpu pinned number when 'unpin',
and since it's protected by space_info->lock, the race is gone now.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
1 parent 130d5b4
History
Tip revision: d288db5dc0110c8e0732d099aaf7a05e2ea0e0c8 authored by Liu Bo on 02 July 2014, 08:58:01 UTC
Btrfs: fix race of using total_bytes_pinned
Tip revision: d288db5
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