Merge tag 'dm-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:
 "A set of device-mapper fixes for 3.13.

  A fix for possible memory corruption during DM table load, fix a
  possible leak of snapshot space in case of a crash, fix a possible
  deadlock due to a shared workqueue in the delay target, fix to
  initialize read-only module parameters that are used to export metrics
  for dm stats and dm bufio.

  Quite a few stable fixes were identified for both the thin-
  provisioning and caching targets as a result of increased regression
  testing using the device-mapper-test-suite (dmts).  The most notable
  of these are the reference counting fixes for the space map btree that
  is used by the dm-array interface -- without these the dm-cache
  metadata will leak, resulting in dm-cache devices running out of
  metadata blocks.  Also, some important fixes related to the
  thin-provisioning target's transition to read-only mode on error"

* tag 'dm-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm array: fix a reference counting bug in shadow_ablock
  dm space map: disallow decrementing a reference count below zero
  dm stats: initialize read-only module parameter
  dm bufio: initialize read-only module parameters
  dm cache: actually resize cache
  dm cache: update Documentation for invalidate_cblocks's range syntax
  dm cache policy mq: fix promotions to occur as expected
  dm thin: allow pool in read-only mode to transition to read-write mode
  dm thin: re-establish read-only state when switching to fail mode
  dm thin: always fallback the pool mode if commit fails
  dm thin: switch to read-only mode if metadata space is exhausted
  dm thin: switch to read only mode if a mapping insert fails
  dm space map metadata: return on failure in sm_metadata_new_block
  dm table: fail dm_table_create on dm_round_up overflow
  dm snapshot: avoid snapshot space leak on crash
  dm delay: fix a possible deadlock due to shared workqueue

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/md/persistent-data/dm-array.c b/drivers/md/persistent-data/dm-array.c
index af96e24ec328..1d75b1dc1e2e 100644
--- a/drivers/md/persistent-data/dm-array.c
+++ b/drivers/md/persistent-data/dm-array.c
@@ -317,8 +317,16 @@ static int shadow_ablock(struct dm_array_info *info, dm_block_t *root,
 	 * The shadow op will often be a noop.  Only insert if it really
 	 * copied data.
 	 */
-	if (dm_block_location(*block) != b)
+	if (dm_block_location(*block) != b) {
+		/*
+		 * dm_tm_shadow_block will have already decremented the old
+		 * block, but it is still referenced by the btree.  We
+		 * increment to stop the insert decrementing it below zero
+		 * when overwriting the old value.
+		 */
+		dm_tm_inc(info->btree_info.tm, b);
 		r = insert_ablock(info, index, *block, root);
+	}
 
 	return r;
 }