Merge tag 'dm-3.19-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:
 "Two stable fixes for dm-cache and one 3.19 DM core fix:

   - fix potential for dm-cache metadata corruption via stale metadata
     buffers being used when switching an inactive cache table to
     active; this could occur due to each table having it's own bufio
     client rather than sharing the client between tables.

   - fix dm-cache target to properly account for discard IO while
     suspending otherwise IO quiescing could complete prematurely.

   - fix DM core's handling of multiple internal suspends by maintaining
     an 'internal_suspend_count' and only resuming the device when this
     count drops to zero"

* tag 'dm-3.19-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: fix handling of multiple internal suspends
  dm cache: fix problematic dual use of a single migration count variable
  dm cache: share cache-metadata object across inactive and active DM tables

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b98cd9d..2caf5b3 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -206,6 +206,9 @@ struct mapped_device {
 	/* zero-length flush that will be cloned and submitted to targets */
 	struct bio flush_bio;
 
+	/* the number of internal suspends */
+	unsigned internal_suspend_count;
+
 	struct dm_stats stats;
 };
 
@@ -2928,7 +2931,7 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla
 {
 	struct dm_table *map = NULL;
 
-	if (dm_suspended_internally_md(md))
+	if (md->internal_suspend_count++)
 		return; /* nested internal suspend */
 
 	if (dm_suspended_md(md)) {
@@ -2953,7 +2956,9 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla
 
 static void __dm_internal_resume(struct mapped_device *md)
 {
-	if (!dm_suspended_internally_md(md))
+	BUG_ON(!md->internal_suspend_count);
+
+	if (--md->internal_suspend_count)
 		return; /* resume from nested internal suspend */
 
 	if (dm_suspended_md(md))