From 0e825862f3c04cee40e25f55680333728a4ffa9b Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 1 Oct 2014 13:29:48 -0400 Subject: [PATCH] dm bufio: when done scanning return from __scan immediately When __scan frees the required number of buffer entries that the shrinker requested (nr_to_scan becomes zero) it must return. Before this fix the __scan code exited only the inner loop and continued in the outer loop -- which could result in reduced performance due to extra buffers being freed (e.g. unnecessarily evicted thinp metadata needing to be synchronously re-read into bufio's cache). Also, move dm_bufio_cond_resched to __scan's inner loop, so that iterating the bufio client's lru lists doesn't result in scheduling latency. Reported-by: Joe Thornber Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org # 3.2+ --- drivers/md/dm-bufio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index eab64bcaab66..9ea5b6041eb2 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1473,9 +1473,9 @@ static long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan, list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) { freed += __cleanup_old_buffer(b, gfp_mask, 0); if (!--nr_to_scan) - break; + return freed; + dm_bufio_cond_resched(); } - dm_bufio_cond_resched(); } return freed; }