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authorMikulas Patocka <mpatocka@redhat.com>2017-04-30 17:34:53 -0400
committerMike Snitzer <snitzer@redhat.com>2017-05-01 15:21:42 -0400
commit390020ad2af9ca04844c4f3b1f299ad8746d84c8 (patch)
treea89be3c8cd0ad3b0959c12eb534c288be9669597 /drivers/md
parent1b0fb5a5b2dc0dddcfa575060441a7176ba7ac37 (diff)
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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 <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-bufio.c10
1 files changed, 10 insertions, 0 deletions
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);