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 Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org # v3.2+ --- drivers/md/dm-bufio.c | 1 + 1 file changed, 1 insertion(+) Index: linux-3.17-rc7/drivers/md/dm-bufio.c =================================================================== --- linux-3.17-rc7.orig/drivers/md/dm-bufio.c 2014-09-30 17:41:31.000000000 +0200 +++ linux-3.17-rc7/drivers/md/dm-bufio.c 2014-09-30 17:41:57.000000000 +0200 @@ -465,6 +465,7 @@ 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; } /*----------------------------------------------------------------