| From 41c73a49df31151f4ff868f28fe4f129f113fa2c Mon Sep 17 00:00:00 2001 |
| From: Mikulas Patocka <mpatocka@redhat.com> |
| Date: Wed, 23 Nov 2016 17:04:00 -0500 |
| Subject: dm bufio: drop the lock when doing GFP_NOIO allocation |
| |
| From: Mikulas Patocka <mpatocka@redhat.com> |
| |
| commit 41c73a49df31151f4ff868f28fe4f129f113fa2c upstream. |
| |
| If the first allocation attempt using GFP_NOWAIT fails, drop the lock |
| and retry using GFP_NOIO allocation (lock is dropped because the |
| allocation can take some time). |
| |
| Note that we won't do GFP_NOIO allocation when we loop for the second |
| time, because the lock shouldn't be dropped between __wait_for_free_buffer |
| and __get_unclaimed_buffer. |
| |
| 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 | 10 ++++++++++ |
| 1 file changed, 10 insertions(+) |
| |
| --- a/drivers/md/dm-bufio.c |
| +++ b/drivers/md/dm-bufio.c |
| @@ -813,6 +813,7 @@ enum new_flag { |
| static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf) |
| { |
| struct dm_buffer *b; |
| + bool tried_noio_alloc = false; |
| |
| /* |
| * dm-bufio is resistant to allocation failures (it just keeps |
| @@ -837,6 +838,15 @@ static struct dm_buffer *__alloc_buffer_ |
| if (nf == NF_PREFETCH) |
| return NULL; |
| |
| + if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) { |
| + dm_bufio_unlock(c); |
| + b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); |
| + dm_bufio_lock(c); |
| + if (b) |
| + return b; |
| + tried_noio_alloc = true; |
| + } |
| + |
| if (!list_empty(&c->reserved_buffers)) { |
| b = list_entry(c->reserved_buffers.next, |
| struct dm_buffer, lru_list); |