WSL2-Linux-Kernel/drivers/md/persistent-data
Hou Tao 474e559567 dm btree: increase rebalance threshold in __rebalance2()
We got the following warnings from thin_check during thin-pool setup:

  $ thin_check /dev/vdb
  examining superblock
  examining devices tree
    missing devices: [1, 84]
      too few entries in btree_node: 41, expected at least 42 (block 138, max_entries = 126)
  examining mapping tree

The phenomenon is the number of entries in one node of details_info tree is
less than (max_entries / 3). And it can be easily reproduced by the following
procedures:

  $ new a thin pool
  $ presume the max entries of details_info tree is 126
  $ new 127 thin devices (e.g. 1~127) to make the root node being full
    and then split
  $ remove the first 43 (e.g. 1~43) thin devices to make the children
    reblance repeatedly
  $ stop the thin pool
  $ thin_check

The root cause is that the B-tree removal procedure in __rebalance2()
doesn't guarantee the invariance: the minimal number of entries in
non-root node should be >= (max_entries / 3).

Simply fix the problem by increasing the rebalance threshold to
make sure the number of entries in each child will be greater
than or equal to (max_entries / 3 + 1), so no matter which
child is used for removal, the number will still be valid.

Cc: stable@vger.kernel.org
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-12-05 15:27:52 -05:00
..
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
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: remove check for impossible sm_find_free() return value 2019-08-26 15:39:53 -04:00
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: fix some book keeping in the disk space map 2017-05-15 15:09:50 -04:00
dm-space-map-disk.h
dm-space-map-metadata.c dm space map metadata: fix missing store of apply_bops() return value 2019-08-22 16:11:24 -04:00
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 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