Joe Thornber cebc2de44d dm space map metadata: fix refcount decrement below 0 which caused corruption ... This has been a relatively long-standing issue that wasn't nailed down until Teng-Feng Yang's meticulous bug report to dm-devel on 3/7/2014, see: http://www.redhat.com/archives/dm-devel/2014-March/msg00021.html From that report: "When decreasing the reference count of a metadata block with its reference count equals 3, we will call dm_btree_remove() to remove this enrty from the B+tree which keeps the reference count info in metadata device. The B+tree will try to rebalance the entry of the child nodes in each node it traversed, and the rebalance process contains the following steps. (1) Finding the corresponding children in current node (shadow_current(s)) (2) Shadow the children block (issue BOP_INC) (3) redistribute keys among children, and free children if necessary (issue BOP_DEC) Since the update of a metadata block's reference count could be recursive, we will stash these reference count update operations in smm->uncommitted and then process them in a FILO fashion. The problem is that step(3) could free the children which is created in step(2), so the BOP_DEC issued in step(3) will be carried out before the BOP_INC issued in step(2) since these BOPs will be processed in FILO fashion. Once the BOP_DEC from step(3) tries to decrease the reference count of newly shadow block, it will report failure for its reference equals 0 before decreasing. It looks like we can solve this issue by processing these BOPs in a FIFO fashion instead of FILO." Commit 5b564d80 ("dm space map: disallow decrementing a reference count below zero") changed the code to report an error for this temporary refcount decrement below zero. So what was previously a harmless invalid refcount became a hard failure due to the new error path: device-mapper: space map common: unable to decrement a reference count below 0 device-mapper: thin: 253:6: dm_thin_insert_block() failed: error = -22 device-mapper: thin: 253:6: switching pool to read-only mode This bug is in dm persistent-data code that is common to the DM thin and cache targets. So any users of those targets should apply this fix. Fix this by applying recursive space map operations in FIFO order rather than FILO. Resolves: https://bugzilla.kernel.org/show_bug.cgi?id=68801 Reported-by: Apollon Oikonomopoulos <apoikos@debian.org> Reported-by: edwillam1007@gmail.com Reported-by: Teng-Feng Yang <shinrairis@gmail.com> Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org # 3.13+		2014-03-07 12:02:47 -05:00
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dm-array.c	dm array: fix a reference counting bug in shadow_ablock	2013-12-13 14:22:10 -05:00
dm-array.h	dm persistent data: add transactional array	2013-03-01 22:45:51 +00:00
dm-bitset.c	dm persistent data: add bitset	2013-03-01 22:45:51 +00:00
dm-bitset.h	dm persistent data: add bitset	2013-03-01 22:45:51 +00:00
dm-block-manager.c	dm persistent data: cleanup dm-thin specific references in text	2014-01-07 10:11:54 -05:00
dm-block-manager.h	dm thin: allow pool in read-only mode to transition to read-write mode	2013-12-10 16:35:13 -05:00
dm-btree-internal.h	dm persistent data: add btree_walk	2013-03-01 22:45:50 +00:00
dm-btree-remove.c	dm thin: fix discard corruption	2013-03-20 17:21:24 +00:00
dm-btree-spine.c	dm persistent data: add btree_walk	2013-03-01 22:45:50 +00:00
dm-btree.c	dm btree: add dm_btree_find_lowest_key	2014-01-09 16:29:17 -05:00
dm-btree.h	dm btree: add dm_btree_find_lowest_key	2014-01-09 16:29:17 -05:00
dm-persistent-data-internal.h
dm-space-map-common.c	dm space map common: make sure new space is used during extend	2014-01-07 21:05:17 -05:00
dm-space-map-common.h	dm persistent data: only commit space map if index changed	2012-07-27 15:08:06 +01:00
dm-space-map-disk.c	dm space map disk: optimise sm_disk_dec_block	2013-11-09 18:20:24 -05:00
dm-space-map-disk.h
dm-space-map-metadata.c	dm space map metadata: fix refcount decrement below 0 which caused corruption	2014-03-07 12:02:47 -05:00
dm-space-map-metadata.h	dm thin: allow metadata space larger than supported to go unused	2014-02-27 11:49:08 -05:00
dm-space-map.h	dm persistent data: add threshold callback to space map	2013-05-10 14:37:20 +01:00
dm-transaction-manager.c	hlist: drop the node parameter from iterators	2013-02-27 19:10:24 -08:00
dm-transaction-manager.h	dm persistent data: tidy transaction manager creation fns	2012-07-27 15:08:09 +01:00
Kconfig	dm: fix Kconfig indentation	2014-03-03 17:31:07 -05:00
Makefile	dm persistent data: add bitset	2013-03-01 22:45:51 +00:00