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authorJoe Thornber <ejt@redhat.com>2013-10-21 12:44:57 +0200
committerMike Snitzer <snitzer@redhat.com>2013-11-09 23:54:34 +0100
commit99ba2ae4cd876bbcedb01d94c1a7952ce171418e (patch)
treee150c06aff63538e6c64ff29a88f6afdb9d9fe20 /drivers/md/dm-cache-policy-mq.c
parentdm array: fix bug in growing array (diff)
downloadlinux-99ba2ae4cd876bbcedb01d94c1a7952ce171418e.tar.xz
linux-99ba2ae4cd876bbcedb01d94c1a7952ce171418e.zip
dm cache policy mq: protect residency method with existing mutex
It is safe to use a mutex in mq_residency() at this point since it is only called from ioctl context. But future-proof mq_residency() by using might_sleep() to catch new contexts that cannot sleep. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-cache-policy-mq.c')
-rw-r--r--drivers/md/dm-cache-policy-mq.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c
index 4296155090b2..db490f74c7f8 100644
--- a/drivers/md/dm-cache-policy-mq.c
+++ b/drivers/md/dm-cache-policy-mq.c
@@ -1001,10 +1001,14 @@ static void mq_force_mapping(struct dm_cache_policy *p,
static dm_cblock_t mq_residency(struct dm_cache_policy *p)
{
+ dm_cblock_t r;
struct mq_policy *mq = to_mq_policy(p);
- /* FIXME: lock mutex, not sure we can block here */
- return to_cblock(mq->nr_cblocks_allocated);
+ mutex_lock(&mq->lock);
+ r = to_cblock(mq->nr_cblocks_allocated);
+ mutex_unlock(&mq->lock);
+
+ return r;
}
static void mq_tick(struct dm_cache_policy *p)