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dm bufio: update last_accessed when relinking a buffer 

The 'last_accessed' member of the dm_buffer structure was only set when
the the buffer was created.  This led to each buffer being discarded
after dm_bufio_max_age time even if it was used recently.  In practice
this resulted in all thinp metadata being evicted soon after being read
-- this is particularly problematic for metadata intensive workloads
like multithreaded small random IO.

'last_accessed' is now updated each time the buffer is moved to the head
of the LRU list, so the buffer is now properly discarded if it was not
used in dm_bufio_max_age time.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v3.2+
This commit is contained in:
Joe Thornber 2014-09-30 09:32:46 +01:00 committed by Mike Snitzer
parent 48cf06bc5f
commit eb76faf53b
1 changed files with 1 additions and 0 deletions
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1
drivers/md/dm-bufio.c
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@ -465,6 +465,7 @@ static void __relink_lru(struct dm_buffer *b, int dirty)
c->n_buffers[dirty]++;
b->list_mode = dirty;
list_move(&b->lru_list, &c->lru[dirty]);
b->last_accessed = jiffies;
}
/*----------------------------------------------------------------