There's a bug in dm-thin in the function rebalance_children. If the
internal btree node has one entry, the code tries to copy all btree
entries from the node's child to the node itself and then decrement the
child's reference count.
If the child node is shared (it has reference count > 1), we won't free
it, so there would be two pointers to each of the grandchildren nodes.
But the reference counts of the grandchildren is not increased, thus the
reference count doesn't match the number of pointers that point to the
grandchildren. This results in "device mapper: space map common: unable
to decrement block" errors.
Fix this bug by incrementing reference counts on the grandchildren if the
btree node is shared.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 3241b1d3e0 ("dm: add persistent data library")
Cc: stable@vger.kernel.org
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
Pull device mapper updates from Mikulas Patocka:
- fix a spelling error in dm-raid
- change kzalloc to kcalloc
- remove useless test in alloc_multiple_bios
- disable REQ_NOWAIT for flushes
- dm-transaction-manager: use red-black trees instead of linear lists
- atomic writes support for dm-linear, dm-stripe and dm-mirror
- dm-crypt: code cleanups and two bugfixes
* tag 'for-6.14/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm-crypt: track tag_offset in convert_context
dm-crypt: don't initialize cc_sector again
dm-crypt: don't update io->sector after kcryptd_crypt_write_io_submit()
dm-crypt: use bi_sector in bio when initialize integrity seed
dm-crypt: fully initialize clone->bi_iter in crypt_alloc_buffer()
dm-crypt: set atomic as false when calling crypt_convert() in kworker
dm-mirror: Support atomic writes
dm-io: Warn on creating multiple atomic write bios for a region
dm-stripe: Enable atomic writes
dm-linear: Enable atomic writes
dm: Ensure cloned bio is same length for atomic write
dm-table: atomic writes support
dm-transaction-manager: use red-black trees instead of linear lists
dm: disable REQ_NOWAIT for flushes
dm: remove useless test in alloc_multiple_bios
dm: change kzalloc to kcalloc
dm raid: fix spelling errors in raid_ctr()
There was reported performance degradation when the shadow map contained
too many entries [1]. The shadow map uses 256-bucket hash with linear
lists - when there are too many entries, it has quadratic complexity.
Meir Elisha proposed to add a module parameter that could configure the
size of the hash array - however, this is not ideal because users don't
know that they should increase the parameter when they get bad
performance.
This commit replaces the linear lists with rb-trees (so that there's a
hash of rb-trees), they have logarithmic complexity, so it solves the
performance degradation.
Link: https://patchwork.kernel.org/project/dm-devel/patch/20241014134944.1264991-1-meir.elisha@volumez.com/ [1]
Reported-by: Meir Elisha <meir.elisha@volumez.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
dm_array_cursor_skip() seeks to the target position by loading array
blocks iteratively until the specified number of entries to skip is
reached. When seeking across block boundaries, it uses
dm_array_cursor_next() to step into the next block.
dm_array_cursor_skip() must first move the cursor index to the end
of the current block; otherwise, the cursor position could incorrectly
remain in the same block, causing the actual number of skipped entries
to be much smaller than expected.
This bug affects cache resizing in v2 metadata and could lead to data
loss if the fast device is shrunk during the first-time resume. For
example:
1. create a cache metadata consists of 32768 blocks, with a dirty block
assigned to the second bitmap block. cache_restore v1.0 is required.
cat <<EOF >> cmeta.xml
<superblock uuid="" block_size="64" nr_cache_blocks="32768" \
policy="smq" hint_width="4">
<mappings>
<mapping cache_block="32767" origin_block="0" dirty="true"/>
</mappings>
</superblock>
EOF
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2
2. bring up the cache while attempt to discard all the blocks belonging
to the second bitmap block (block# 32576 to 32767). The last command
is expected to fail, but it actually succeeds.
dmsetup create cdata --table "0 2084864 linear /dev/sdc 8192"
dmsetup create corig --table "0 65536 linear /dev/sdc 2105344"
dmsetup create cache --table "0 65536 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 64 2 metadata2 writeback smq \
2 migration_threshold 0"
In addition to the reproducer described above, this fix can be
verified using the "array_cursor/skip" tests in dm-unit:
dm-unit run /pdata/array_cursor/skip/ --kernel-dir <KERNEL_DIR>
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Fixes: 9b696229aa ("dm persistent data: add cursor skip functions to the cursor APIs")
Reviewed-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
The cached block pointer in dm_array_cursor might be NULL if it reaches
an unreadable array block, or the array is empty. Therefore,
dm_array_cursor_end() should call dm_btree_cursor_end() unconditionally,
to prevent leaving unreleased btree blocks.
This fix can be verified using the "array_cursor/iterate/empty" test
in dm-unit:
dm-unit run /pdata/array_cursor/iterate/empty --kernel-dir <KERNEL_DIR>
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Fixes: fdd1315aa5 ("dm array: introduce cursor api")
Reviewed-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Remove the redundant "i" at the beginning of the error message. This "i"
came from commit 1c13188669 ("dm: prefer
'"%s...", __func__'"), the "i" is accidentally left.
Signed-off-by: Ssuhung Yeh <ssuhung@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 1c13188669 ("dm: prefer '"%s...", __func__'")
Cc: stable@vger.kernel.org # v6.3+
kmalloc is unreliable when allocating more than 8 pages of memory. It may
fail when there is plenty of free memory but the memory is fragmented.
Zdenek Kabelac observed such failure in his tests.
This commit changes kmalloc to kvmalloc - kvmalloc will fall back to
vmalloc if the large allocation fails.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Reviewed-by: Mike Snitzer <snitzer@kernel.org>
Cc: stable@vger.kernel.org
'struct dm_block_validator' are not modified in these drivers.
Constifying this structure moves some data to a read-only section, so
increase overall security.
On a x86_64, with allmodconfig, as an example:
Before:
======
text data bss dec hex filename
32047 920 16 32983 80d7 drivers/md/dm-cache-metadata.o
After:
=====
text data bss dec hex filename
32075 896 16 32987 80db drivers/md/dm-cache-metadata.o
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
As described in commit 8111964f1b ("dm thin: Fix ABBA deadlock between
shrink_slab and dm_pool_abort_metadata"), ABBA deadlocks will be
triggered because shrinker_rwsem currently needs to held by
dm_pool_abort_metadata() as a side-effect of thin-pool metadata
operation failure.
The following three problem scenarios have been noticed:
1) Described by commit 8111964f1b ("dm thin: Fix ABBA deadlock between
shrink_slab and dm_pool_abort_metadata")
2) shrinker_rwsem and throttle->lock
P1(drop cache) P2(kworker)
drop_caches_sysctl_handler
drop_slab
shrink_slab
down_read(&shrinker_rwsem) - LOCK A
do_shrink_slab
super_cache_scan
prune_icache_sb
dispose_list
evict
ext4_evict_inode
ext4_clear_inode
ext4_discard_preallocations
ext4_mb_load_buddy_gfp
ext4_mb_init_cache
ext4_wait_block_bitmap
__ext4_error
ext4_handle_error
ext4_commit_super
...
dm_submit_bio
do_worker
throttle_work_update
down_write(&t->lock) -- LOCK B
process_deferred_bios
commit
metadata_operation_failed
dm_pool_abort_metadata
dm_block_manager_create
dm_bufio_client_create
register_shrinker
down_write(&shrinker_rwsem)
-- LOCK A
thin_map
thin_bio_map
thin_defer_bio_with_throttle
throttle_lock
down_read(&t->lock) - LOCK B
3) shrinker_rwsem and wait_on_buffer
P1(drop cache) P2(kworker)
drop_caches_sysctl_handler
drop_slab
shrink_slab
down_read(&shrinker_rwsem) - LOCK A
do_shrink_slab
...
ext4_wait_block_bitmap
__ext4_error
ext4_handle_error
jbd2_journal_abort
jbd2_journal_update_sb_errno
jbd2_write_superblock
submit_bh
// LOCK B
// RELEASE B
do_worker
throttle_work_update
down_write(&t->lock) - LOCK B
process_deferred_bios
process_bio
commit
metadata_operation_failed
dm_pool_abort_metadata
dm_block_manager_create
dm_bufio_client_create
register_shrinker
register_shrinker_prepared
down_write(&shrinker_rwsem) - LOCK A
bio_endio
wait_on_buffer
__wait_on_buffer
Fix these by resetting dm_bufio_client without holding shrinker_rwsem.
Fixes: 8111964f1b ("dm thin: Fix ABBA deadlock between shrink_slab and dm_pool_abort_metadata")
Cc: stable@vger.kernel.org
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
