From 390020ad2af9ca04844c4f3b1f299ad8746d84c8 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Sun, 30 Apr 2017 17:34:53 -0400 Subject: [PATCH] dm bufio: check new buffer allocation watermark every 30 seconds dm-bufio checks a watermark when it allocates a new buffer in __bufio_new(). However, it doesn't check the watermark when the user changes /sys/module/dm_bufio/parameters/max_cache_size_bytes. This may result in a problem - if the watermark is high enough so that all possible buffers are allocated and if the user lowers the value of "max_cache_size_bytes", the watermark will never be checked against the new value because no new buffer would be allocated. To fix this, change __evict_old_buffers() so that it checks the watermark. __evict_old_buffers() is called every 30 seconds, so if the user reduces "max_cache_size_bytes", dm-bufio will react to this change within 30 seconds and decrease memory consumption. Depends-on: 1b0fb5a5b2 ("dm bufio: avoid a possible ABBA deadlock") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- drivers/md/dm-bufio.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index fd28146dd952..c92c31b23e54 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1796,9 +1796,17 @@ static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz) struct dm_buffer *b, *tmp; unsigned retain_target = get_retain_buffers(c); unsigned count; + LIST_HEAD(write_list); dm_bufio_lock(c); + __check_watermark(c, &write_list); + if (unlikely(!list_empty(&write_list))) { + dm_bufio_unlock(c); + __flush_write_list(&write_list); + dm_bufio_lock(c); + } + count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) { if (count <= retain_target) @@ -1823,6 +1831,8 @@ static void cleanup_old_buffers(void) mutex_lock(&dm_bufio_clients_lock); + __cache_size_refresh(); + list_for_each_entry(c, &dm_bufio_all_clients, client_list) __evict_old_buffers(c, max_age_hz); -- 2.11.0