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Subject[PATCH 3.10 036/123] dm bufio: update last_accessed when relinking a buffer
Date
3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joe Thornber <ejt@redhat.com>

commit eb76faf53b1ff7a77ce3f78cc98ad392ac70c2a0 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/dm-bufio.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -462,6 +462,7 @@ static void __relink_lru(struct dm_buffe
c->n_buffers[dirty]++;
b->list_mode = dirty;
list_move(&b->lru_list, &c->lru[dirty]);
+ b->last_accessed = jiffies;
}

/*----------------------------------------------------------------



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