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dm bufio: change __GFP_IO to __GFP_FS in shrinker callbacks 

The shrinker uses gfp flags to indicate what kind of operation can the
driver wait for. If __GFP_IO flag is present, the driver can wait for
block I/O operations, if __GFP_FS flag is present, the driver can wait on
operations involving the filesystem.

dm-bufio tested for __GFP_IO. However, dm-bufio can run on a loop block
device that makes calls into the filesystem. If __GFP_IO is present and
__GFP_FS isn't, dm-bufio could still block on filesystem operations if it
runs on a loop block device.

The change from __GFP_IO to __GFP_FS supposedly fixes one observed (though
unreproducible) deadlock involving dm-bufio and loop device.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Mikulas Patocka 2014-10-16 14:45:20 -04:00 committed by Mike Snitzer
parent a3f2af2547
commit 9d28eb1244
1 changed files with 6 additions and 6 deletions
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12
drivers/md/dm-bufio.c
View File

@ -1435,9 +1435,9 @@ static void drop_buffers(struct dm_bufio_client *c)
/*
* Test if the buffer is unused and too old, and commit it.
* At if noio is set, we must not do any I/O because we hold
* dm_bufio_clients_lock and we would risk deadlock if the I/O gets rerouted to
* different bufio client.
* And if GFP_NOFS is used, we must not do any I/O because we hold
* dm_bufio_clients_lock and we would risk deadlock if the I/O gets
* rerouted to different bufio client.
*/
static int __cleanup_old_buffer(struct dm_buffer *b, gfp_t gfp,
unsigned long max_jiffies)
@ -1445,7 +1445,7 @@ static int __cleanup_old_buffer(struct dm_buffer *b, gfp_t gfp,
if (jiffies - b->last_accessed < max_jiffies)
return 0;
if (!(gfp & __GFP_IO)) {
if (!(gfp & __GFP_FS)) {
if (test_bit(B_READING, &b->state) ||
test_bit(B_WRITING, &b->state) ||
test_bit(B_DIRTY, &b->state))
@ -1487,7 +1487,7 @@ dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
unsigned long freed;
c = container_of(shrink, struct dm_bufio_client, shrinker);
if (sc->gfp_mask & __GFP_IO)
if (sc->gfp_mask & __GFP_FS)
dm_bufio_lock(c);
else if (!dm_bufio_trylock(c))
return SHRINK_STOP;
@ -1504,7 +1504,7 @@ dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
unsigned long count;
c = container_of(shrink, struct dm_bufio_client, shrinker);
if (sc->gfp_mask & __GFP_IO)
if (sc->gfp_mask & __GFP_FS)
dm_bufio_lock(c);
else if (!dm_bufio_trylock(c))
return 0;