dm bufio: drop the lock when doing GFP_NOIO allocation (41c73a49) · Commits · 戴 / test

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>

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);

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