1. 07 Jul, 2022 10 commits
    • Mauro Carvalho Chehab's avatar
      Documentation: dm writecache: add blank line before optional parameters · 8b301af4
      Mauro Carvalho Chehab authored
      Otherwise this warning occurs:
        Documentation/admin-guide/device-mapper/writecache.rst:23: WARNING: Unexpected indentation.
      Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@kernel.org>
      Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
      8b301af4
    • Zhang Jiaming's avatar
      962c6296
    • Jiang Jian's avatar
    • Steven Lung's avatar
      dm cache: fix typo in 2 comment blocks · 5c29e784
      Steven Lung authored
      Replace neccessarily with necessarily.
      Signed-off-by: default avatarSteven Lung <1030steven@gmail.com>
      Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
      5c29e784
    • JeongHyeon Lee's avatar
      dm verity: fix checkpatch close brace error · 20e6fc85
      JeongHyeon Lee authored
      Resolves: ERROR: else should follow close brace '}'
      Signed-off-by: default avatarJeongHyeon Lee <jhs2.lee@samsung.com>
      Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
      20e6fc85
    • Mike Snitzer's avatar
      dm table: rename dm_target variable in dm_table_add_target() · 899ab445
      Mike Snitzer authored
      Rename from "tgt" to "ti" so that all of dm-table.c code uses the same
      naming for dm_target variables.
      Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
      899ab445
    • Mike Snitzer's avatar
      dm table: audit all dm_table_get_target() callers · 564b5c54
      Mike Snitzer authored
      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: default avatarMike Snitzer <snitzer@kernel.org>
      564b5c54
    • Mike Snitzer's avatar
      dm table: remove dm_table_get_num_targets() wrapper · 2aec377a
      Mike Snitzer authored
      More efficient and readable to just access table->num_targets directly.
      Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
      2aec377a
    • Ming Lei's avatar
      dm: add two stage requeue mechanism · 8b211aac
      Ming Lei authored
      Commit 61b6e2e5 ("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
      7dd76d1f ("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
      61b6e2e5.
      
      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: default avatarMing Lei <ming.lei@redhat.com>
      Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
      8b211aac
    • Ming Lei's avatar
      dm: add dm_bio_rewind() API to DM core · 61cbe788
      Ming Lei authored
      Commit 7759eb23 ("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 5151842b (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 7dd76d1f ("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: default avatarJens Axboe <axboe@kernel.dk>
      Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
      Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
      61cbe788
  2. 29 Jun, 2022 6 commits
  3. 28 Jun, 2022 12 commits
  4. 27 Jun, 2022 12 commits