| Message ID | 20240411201529.44846-2-snitzer@kernel.org (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
| Series | dm: use late bio-splitting and queue_limits_set | expand |
Yes, this is the right thing to to:
Reviewed-by: Christoph Hellwig <hch@lst.de>
On Thu, 11 Apr 2024, Mike Snitzer wrote: > This change effectively reverts commit 586b286b110e ("dm crypt: > constrain crypt device's max_segment_size to PAGE_SIZE") and relies on > block core's late bio-splitting to ensure that dm-crypt's encryption > bios are split accordingly if they exceed the underlying device's > limits (e.g. max_segment_size). > > Commit 586b286b110e was applied as a 4.3 fix for the benefit of > stable@ kernels 4.0+ just after block core's late bio-splitting was > introduced in 4.3 with commit 54efd50bfd873 ("block: make > generic_make_request handle arbitrarily sized bios"). Given block > core's late bio-splitting it is past time that dm-crypt make use of > it. > > Also, given the recent need to revert meaningful progress that was > attempted during the 6.9 merge window (see commit bff4b74625fe Revert > "dm: use queue_limits_set") this change allows DM core to safely make > use of queue_limits_set() without risk of breaking dm-crypt on NVMe. > Though it should be noted this commit isn't a prereq for reinstating > DM core's use of queue_limits_set() because blk_validate_limits() was > made less strict with commit b561ea56a264 ("block: allow device to > have both virt_boundary_mask and max segment size"). > > Signed-off-by: Mike Snitzer <snitzer@kernel.org> Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> > --- > drivers/md/dm-crypt.c | 12 ++---------- > 1 file changed, 2 insertions(+), 10 deletions(-) > > diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c > index 5bfa35760167..f43a2c0b3d77 100644 > --- a/drivers/md/dm-crypt.c > +++ b/drivers/md/dm-crypt.c > @@ -1656,8 +1656,8 @@ static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone); > > /* > * Generate a new unfragmented bio with the given size > - * This should never violate the device limitations (but only because > - * max_segment_size is being constrained to PAGE_SIZE). > + * This should never violate the device limitations (but if it did then block > + * core should split the bio as needed). > * > * This function may be called concurrently. If we allocate from the mempool > * concurrently, there is a possibility of deadlock. For example, if we have > @@ -3717,14 +3717,6 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits) > { > struct crypt_config *cc = ti->private; > > - /* > - * Unfortunate constraint that is required to avoid the potential > - * for exceeding underlying device's max_segments limits -- due to > - * crypt_alloc_buffer() possibly allocating pages for the encryption > - * bio that are not as physically contiguous as the original bio. > - */ > - limits->max_segment_size = PAGE_SIZE; > - > limits->logical_block_size = > max_t(unsigned int, limits->logical_block_size, cc->sector_size); > limits->physical_block_size = > -- > 2.40.0 >
On Thu, Apr 11, 2024 at 04:15:28PM -0400, Mike Snitzer wrote: > This change effectively reverts commit 586b286b110e ("dm crypt: > constrain crypt device's max_segment_size to PAGE_SIZE") and relies on > block core's late bio-splitting to ensure that dm-crypt's encryption > bios are split accordingly if they exceed the underlying device's > limits (e.g. max_segment_size). > > Commit 586b286b110e was applied as a 4.3 fix for the benefit of > stable@ kernels 4.0+ just after block core's late bio-splitting was > introduced in 4.3 with commit 54efd50bfd873 ("block: make > generic_make_request handle arbitrarily sized bios"). Given block > core's late bio-splitting it is past time that dm-crypt make use of > it. > > Also, given the recent need to revert meaningful progress that was > attempted during the 6.9 merge window (see commit bff4b74625fe Revert > "dm: use queue_limits_set") this change allows DM core to safely make > use of queue_limits_set() without risk of breaking dm-crypt on NVMe. > Though it should be noted this commit isn't a prereq for reinstating > DM core's use of queue_limits_set() because blk_validate_limits() was > made less strict with commit b561ea56a264 ("block: allow device to > have both virt_boundary_mask and max segment size"). > > Signed-off-by: Mike Snitzer <snitzer@kernel.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Thanks, Ming
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 5bfa35760167..f43a2c0b3d77 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -1656,8 +1656,8 @@ static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone); /* * Generate a new unfragmented bio with the given size - * This should never violate the device limitations (but only because - * max_segment_size is being constrained to PAGE_SIZE). + * This should never violate the device limitations (but if it did then block + * core should split the bio as needed). * * This function may be called concurrently. If we allocate from the mempool * concurrently, there is a possibility of deadlock. For example, if we have @@ -3717,14 +3717,6 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits) { struct crypt_config *cc = ti->private; - /* - * Unfortunate constraint that is required to avoid the potential - * for exceeding underlying device's max_segments limits -- due to - * crypt_alloc_buffer() possibly allocating pages for the encryption - * bio that are not as physically contiguous as the original bio. - */ - limits->max_segment_size = PAGE_SIZE; - limits->logical_block_size = max_t(unsigned int, limits->logical_block_size, cc->sector_size); limits->physical_block_size =
This change effectively reverts commit 586b286b110e ("dm crypt: constrain crypt device's max_segment_size to PAGE_SIZE") and relies on block core's late bio-splitting to ensure that dm-crypt's encryption bios are split accordingly if they exceed the underlying device's limits (e.g. max_segment_size). Commit 586b286b110e was applied as a 4.3 fix for the benefit of stable@ kernels 4.0+ just after block core's late bio-splitting was introduced in 4.3 with commit 54efd50bfd873 ("block: make generic_make_request handle arbitrarily sized bios"). Given block core's late bio-splitting it is past time that dm-crypt make use of it. Also, given the recent need to revert meaningful progress that was attempted during the 6.9 merge window (see commit bff4b74625fe Revert "dm: use queue_limits_set") this change allows DM core to safely make use of queue_limits_set() without risk of breaking dm-crypt on NVMe. Though it should be noted this commit isn't a prereq for reinstating DM core's use of queue_limits_set() because blk_validate_limits() was made less strict with commit b561ea56a264 ("block: allow device to have both virt_boundary_mask and max segment size"). Signed-off-by: Mike Snitzer <snitzer@kernel.org> --- drivers/md/dm-crypt.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-)