[PATCH] RAID5: Change kmem_cache name string of RAID 4/5/6 stripe cache

[Jonathan Brassow <jbrassow@redhat.com>]

The unique portion of the kmem_cache name used when dm-raid is creating
a RAID 4/5/6 array is the memory address of it's associated 'mddev'
structure.  This is not always unique.  The memory associated
with the 'mddev' structure can be freed and a future 'mddev' structure
can be allocated from the exact same spot.  This causes an identical
name to the old cache to be created when kmem_cache_create is called.
If an old name is still present amoung slab_caches due to cache merging,
the call will fail.  This is not theoretical, I see this regularly when
performing device-mapper RAID 4/5/6 tests (although, strangely only on
Fedora-19).

Making the unique portion of the kmem_cache name based on jiffies fixes
this problem.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
---
 drivers/md/raid5.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7ff4f25..f731ce9 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1618,7 +1618,7 @@ static int grow_stripes(struct r5conf *conf, int num)
 			"raid%d-%s", conf->level, mdname(conf->mddev));
 	else
 		sprintf(conf->cache_name[0],
-			"raid%d-%p", conf->level, conf->mddev);
+			"raid%d-%llu", conf->level, get_jiffies_64());
 	sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
 
 	conf->active_name = 0;
-- 
1.7.7.6

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