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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: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2016-11-23 17:04:00 -05:00 committed by Mike Snitzer
parent d12067f428
commit 41c73a49df
1 changed files with 10 additions and 0 deletions
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10
drivers/md/dm-bufio.c
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@ -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);