linux/drivers/md/persistent-data
Joe Thornber 4feaef830d dm space map common: fix to ensure new block isn't already in use
The space-maps track the reference counts for disk blocks allocated by
both the thin-provisioning and cache targets.  There are variants for
tracking metadata blocks and data blocks.

Transactionality is implemented by never touching blocks from the
previous transaction, so we can rollback in the event of a crash.

When allocating a new block we need to ensure the block is free (has
reference count of 0) in both the current and previous transaction.
Prior to this fix we were doing this by searching for a free block in
the previous transaction, and relying on a 'begin' counter to track
where the last allocation in the current transaction was.  This
'begin' field was not being updated in all code paths (eg, increment
of a data block reference count due to breaking sharing of a neighbour
block in the same btree leaf).

This fix keeps the 'begin' field, but now it's just a hint to speed up
the search.  Instead the current transaction is searched for a free
block, and then the old transaction is double checked to ensure it's
free.  Much simpler.

This fixes reports of sm_disk_new_block()'s BUG_ON() triggering when
DM thin-provisioning's snapshots are heavily used.

Reported-by: Eric Wheeler <dm-devel@lists.ewheeler.net>
Cc: stable@vger.kernel.org
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-01-14 20:15:53 -05:00
..
dm-array.c dm persistent data: add cursor skip functions to the cursor APIs 2017-02-16 13:12:50 -05:00
dm-array.h dm persistent data: add cursor skip functions to the cursor APIs 2017-02-16 13:12:50 -05:00
dm-bitset.c dm persistent data: add cursor skip functions to the cursor APIs 2017-02-16 13:12:50 -05:00
dm-bitset.h dm persistent data: add cursor skip functions to the cursor APIs 2017-02-16 13:12:50 -05:00
dm-block-manager.c dm persistent data: Simplify stack trace handling 2019-04-29 12:37:52 +02:00
dm-block-manager.h dm block manager: remove an unused argument from dm_block_manager_create() 2017-04-27 17:08:41 -04:00
dm-btree-internal.h dm persistent data: eliminate unnecessary return values 2015-10-31 19:06:02 -04:00
dm-btree-remove.c dm btree: increase rebalance threshold in __rebalance2() 2019-12-05 15:27:52 -05:00
dm-btree-spine.c dm persistent data: eliminate unnecessary return values 2015-10-31 19:06:02 -04:00
dm-btree.c dm btree: fix order of block initialization in btree_split_beneath 2019-08-22 16:11:23 -04:00
dm-btree.h dm persistent data: add cursor skip functions to the cursor APIs 2017-02-16 13:12:50 -05:00
dm-persistent-data-internal.h
dm-space-map-common.c dm space map common: fix to ensure new block isn't already in use 2020-01-14 20:15:53 -05:00
dm-space-map-common.h dm space map common: fix to ensure new block isn't already in use 2020-01-14 20:15:53 -05:00
dm-space-map-disk.c dm space map common: fix to ensure new block isn't already in use 2020-01-14 20:15:53 -05:00
dm-space-map-disk.h
dm-space-map-metadata.c dm space map common: fix to ensure new block isn't already in use 2020-01-14 20:15:53 -05:00
dm-space-map-metadata.h
dm-space-map.h
dm-transaction-manager.c dm persistent data: eliminate unnecessary return values 2015-10-31 19:06:02 -04:00
dm-transaction-manager.h dm persistent data: eliminate unnecessary return values 2015-10-31 19:06:02 -04:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00