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Commit 41c73a49 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
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dm bufio: drop the lock when doing GFP_NOIO allocation 



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: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent d12067f4

drivers/md/dm-bufio.c

+10 −0
Original line number Diff line number Diff line
@@ -822,6 +822,7 @@ 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
@@ -846,6 +847,15 @@ static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client 
		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);