kernel.git/drivers/md/dm-core.h, branch linux-6.7.y

dm: limit the number of targets and parameter size area

2024-02-23T08:51:59Z

commit bd504bcfec41a503b32054da5472904b404341a4 upstream. The kvmalloc function fails with a warning if the size is larger than INT_MAX. The warning was triggered by a syscall testing robot. In order to avoid the warning, this commit limits the number of targets to 1048576 and the size of the parameter area to 1073741824. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm: fix a race condition in retrieve_deps

2023-09-14T15:18:29Z

There's a race condition in the multipath target when retrieve_deps races with multipath_message calling dm_get_device and dm_put_device. retrieve_deps walks the list of open devices without holding any lock but multipath may add or remove devices to the list while it is running. The end result may be memory corruption or use-after-free memory access. See this description of a UAF with multipath_message(): https://listman.redhat.com/archives/dm-devel/2022-October/052373.html Fix this bug by introducing a new rw semaphore "devices_lock". We grab devices_lock for read in retrieve_deps and we grab it for write in dm_get_device and dm_put_device. Reported-by: Luo Meng Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Tested-by: Li Lingfeng Signed-off-by: Mike Snitzer

dm: support turning off block-core's io stats accounting

2023-06-16T22:24:13Z

Commit bc58ba9468d9 ("block: add sysfs file for controlling io stats accounting") allowed users to turn off disk stat accounting completely by checking if queue flag QUEUE_FLAG_IO_STAT is set. In dm, this flag is neither set nor checked: so block-core's io stats are continuously counted and cannot be turned off. Add support for turning off block-core's io stats accounting for dm. Set QUEUE_FLAG_IO_STAT for dm's request_queue. If QUEUE_FLAG_IO_STAT is set when an io starts, record the need for block core's io stats by setting the DM_IO_BLK_STAT dm_io flag to avoid io stats being disabled in the middle of the io. DM statistics (dm-stats) is independent of block-core's io stats and remains unchanged. Signed-off-by: Li Nan Signed-off-by: Mike Snitzer

block: replace fmode_t with a block-specific type for block open flags

2023-06-12T14:04:05Z

The only overlap between the block open flags mapped into the fmode_t and other uses of fmode_t are FMODE_READ and FMODE_WRITE. Define a new blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and ->ioctl and stop abusing fmode_t. Signed-off-by: Christoph Hellwig Acked-by: Jack Wang [rnbd] Reviewed-by: Hannes Reinecke Reviewed-by: Christian Brauner Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de Signed-off-by: Jens Axboe

dm: add argument identifier names

2023-02-14T19:23:06Z

Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer

dm: change "unsigned" to "unsigned int"

2023-02-14T19:23:06Z

Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer

dm: add missing SPDX-License-Indentifiers

2023-02-14T19:23:06Z

'GPL-2.0-only' is used instead of 'GPL-2.0' because SPDX has deprecated its use. Suggested-by: John Wiele Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer

dm table: audit all dm_table_get_target() callers

2022-07-07T15:49:34Z

All callers of dm_table_get_target() are expected to do proper bounds checking on the index they pass. Move dm_table_get_target() to dm-core.h to make it extra clear that only DM core code should be using it. Switch it to be inlined while at it. Standardize all DM core callers to use the same for loop pattern and make associated variables as local as possible. Rename some variables (e.g. s/table/t/ and s/tgt/ti/) along the way. Signed-off-by: Mike Snitzer

dm: add two stage requeue mechanism

2022-07-07T15:49:32Z

Commit 61b6e2e5321d ("dm: fix BLK_STS_DM_REQUEUE handling when dm_io represents split bio") reverted DM core's bio splitting back to using bio_split()+bio_chain() because it was found that otherwise DM's BLK_STS_DM_REQUEUE would trigger a live-lock waiting for bio completion that would never occur. Restore using bio_trim()+bio_inc_remaining(), like was done in commit 7dd76d1feec7 ("dm: improve bio splitting and associated IO accounting"), but this time with proper handling for the above scenario that is covered in more detail in the commit header for 61b6e2e5321d. Solve this issue by adding a two staged dm_io requeue mechanism that uses the new dm_bio_rewind() via dm_io_rewind(): 1) requeue the dm_io into the requeue_list added to struct mapped_device, and schedule it via new added requeue work. This workqueue just clones the dm_io->orig_bio (which DM saves and ensures its end sector isn't modified). dm_io_rewind() uses the sectors and sectors_offset members of the dm_io that are recorded relative to the end of orig_bio: dm_bio_rewind()+bio_trim() are then used to make that cloned bio reflect the subset of the original bio that is represented by the dm_io that is being requeued. 2) the 2nd stage requeue is same with original requeue, but io->orig_bio points to new cloned bio (which matches the requeued dm_io as described above). This allows DM core to shift the need for bio cloning from bio-split time (during IO submission) to the less likely BLK_STS_DM_REQUEUE handling (after IO completes with that error). Signed-off-by: Ming Lei Signed-off-by: Mike Snitzer

dm: add dm_bio_rewind() API to DM core

2022-07-07T15:26:55Z

Commit 7759eb23fd98 ("block: remove bio_rewind_iter()") removed a similar API for the following reasons: ``` It is pointed that bio_rewind_iter() is one very bad API[1]: 1) bio size may not be restored after rewinding 2) it causes some bogus change, such as 5151842b9d8732 (block: reset bi_iter.bi_done after splitting bio) 3) rewinding really makes things complicated wrt. bio splitting 4) unnecessary updating of .bi_done in fast path [1] https://marc.info/?t=153549924200005&r=1&w=2 So this patch takes Kent's suggestion to restore one bio into its original state via saving bio iterator(struct bvec_iter) in bio_integrity_prep(), given now bio_rewind_iter() is only used by bio integrity code. ``` However, saving off a copy of the 32 bytes bio->bi_iter in case rewind needed isn't efficient because it bloats per-bio-data for what is an unlikely case. That suggestion also ignores the need to restore crypto and integrity info. Add dm_bio_rewind() API for a specific use-case that is much more narrow than the previous more generic rewind code that was reverted: 1) most bios have a fixed end sector since bio split is done from front of the bio, if driver just records how many sectors between current bio's start sector and the original bio's end sector, the original position can be restored. Keeping the original bio's end sector fixed is a _hard_ requirement for this interface! 2) if a bio's end sector won't change (usually bio_trim() isn't called, or in the case of DM it preserves original bio), user can restore the original position by storing sector offset from the current ->bi_iter.bi_sector to bio's end sector; together with saving bio size, only 8 bytes is needed to restore to original bio. 3) DM's requeue use case: when BLK_STS_DM_REQUEUE happens, DM core needs to restore to an "original bio" which represents the current dm_io to be requeued (which may be a subset of the original bio). By storing the sector offset from the original bio's end sector and dm_io's size, dm_bio_rewind() can restore such original bio. See commit 7dd76d1feec7 ("dm: improve bio splitting and associated IO accounting") for more details on how DM does this. Leveraging this, allows DM core to shift the need for bio cloning from bio-split time (during IO submission) to the less likely BLK_STS_DM_REQUEUE handling (after IO completes with that error). 4) Unlike the original rewind API, dm_bio_rewind() doesn't add .bi_done to bvec_iter and there is no effect on the fast path. Implement dm_bio_rewind() by factoring out clear helpers that it calls: dm_bio_integrity_rewind, dm_bio_crypt_rewind and dm_bio_rewind_iter. DM is able to ensure that dm_bio_rewind() is used safely but, given the constraint that the bio's end must never change, other hypothetical future callers may not take the same care. So make dm_bio_rewind() and all supporting code local to DM to avoid risk of hypothetical abuse. A "dm_" prefix was added to all functions to avoid any namespace collisions. Suggested-by: Jens Axboe Signed-off-by: Ming Lei Signed-off-by: Mike Snitzer