linux.git/drivers/md/dm-table.c, branch v5.10

dm: fix IO splitting

2020-12-04T19:53:15+00:00

Commit 882ec4e609c1 ("dm table: stack 'chunk_sectors' limit to account
for target-specific splitting") caused a couple regressions:
1) Using lcm_not_zero() when stacking chunk_sectors was a bug because
   chunk_sectors must reflect the most limited of all devices in the
   IO stack.
2) DM targets that set max_io_len but that do _not_ provide an
   .iterate_devices method no longer had there IO split properly.

And commit 5091cdec56fa ("dm: change max_io_len() to use
blk_max_size_offset()") also caused a regression where DM no longer
supported varied (per target) IO splitting. The implication being the
potential for severely reduced performance for IO stacks that use a DM
target like dm-cache to hide performance limitations of a slower
device (e.g. one that requires 4K IO splitting).

Coming full circle: Fix all these issues by discontinuing stacking
chunk_sectors up using ti->max_io_len in dm_calculate_queue_limits(),
add optional chunk_sectors override argument to blk_max_size_offset()
and update DM's max_io_len() to pass ti->max_io_len to its
blk_max_size_offset() call.

Passing in an optional chunk_sectors override to blk_max_size_offset()
allows for code reuse of block's centralized calculation for max IO
size based on provided offset and split boundary.

Fixes: 882ec4e609c1 ("dm table: stack 'chunk_sectors' limit to account for target-specific splitting")
Fixes: 5091cdec56fa ("dm: change max_io_len() to use blk_max_size_offset()")
Cc: stable@vger.kernel.org
Reported-by: John Dorminy 
Reported-by: Bruce Johnston 
Reported-by: Kirill Tkhai 
Reviewed-by: John Dorminy 
Signed-off-by: Mike Snitzer 
Reviewed-by: Jens Axboe

dm table: Remove BUG_ON(in_interrupt())

2020-12-01T20:43:38+00:00

The BUG_ON(in_interrupt()) in dm_table_event() is a historic leftover from
a rework of the dm table code which changed the calling context.

Issuing a BUG for a wrong calling context is frowned upon and
in_interrupt() is deprecated and only covering parts of the wrong
contexts. The sanity check for the context is covered by
CONFIG_DEBUG_ATOMIC_SLEEP and other debug facilities already.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Mike Snitzer

dm: remove special-casing of bio-based immutable singleton target on NVMe

2020-10-07T22:08:41+00:00

Since commit 5a6c35f9af416 ("block: remove direct_make_request") there
is no benefit to DM special-casing NVMe. Remove all code used to
establish DM_TYPE_NVME_BIO_BASED.

Signed-off-by: Mike Snitzer

dm table: make 'struct dm_table' definition accessible to all of DM core

2020-09-29T20:33:07+00:00

Move 'struct dm_table' definition from dm-table.c to dm-core.h and
update DM core to access its members directly.

Helps optimize max_io_len() and other methods slightly.

Signed-off-by: Mike Snitzer

dm table: stack 'chunk_sectors' limit to account for target-specific splitting

2020-09-29T20:33:01+00:00

If target set ti->max_io_len it must be used when stacking
DM device's queue_limits to establish a 'chunk_sectors' that is
compatible with the IO stack.

By using lcm_not_zero() care is taken to avoid blindly overriding the
chunk_sectors limit stacked up by blk_stack_limits().

Depends-on: 07d098e6bbad ("block: allow 'chunk_sectors' to be non-power-of-2")
Signed-off-by: Mike Snitzer

Merge remote-tracking branch 'jens/for-5.10/block' into dm-5.10

2020-09-29T20:31:35+00:00

DM depends on these block 5.10 commits:

22ada802ede8 block: use lcm_not_zero() when stacking chunk_sectors
07d098e6bbad block: allow 'chunk_sectors' to be non-power-of-2
021a24460dc2 block: add QUEUE_FLAG_NOWAIT
6abc49468eea dm: add support for REQ_NOWAIT and enable it for linear target

Signed-off-by: Mike Snitzer

dm: add support for REQ_NOWAIT and enable it for linear target

2020-09-25T14:20:03+00:00

Add DM target feature flag DM_TARGET_NOWAIT which advertises that
target works with REQ_NOWAIT bios.

Add dm_table_supports_nowait() and update dm_table_set_restrictions()
to set/clear QUEUE_FLAG_NOWAIT accordingly.

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jens Axboe

block: add a bdev_is_partition helper

2020-09-25T14:18:57+00:00

Add a littler helper to make the somewhat arcane bd_contains checks a
little more obvious.

Signed-off-by: Christoph Hellwig 
Acked-by: Ulf Hansson 
Signed-off-by: Jens Axboe

bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag

2020-09-24T19:43:39+00:00

The BDI_CAP_STABLE_WRITES is one of the few bits of information in the
backing_dev_info shared between the block drivers and the writeback code.
To help untangling the dependency replace it with a queue flag and a
superblock flag derived from it.  This also helps with the case of e.g.
a file system requiring stable writes due to its own checksumming, but
not forcing it on other users of the block device like the swap code.

One downside is that we an't support the stable_pages_required bdi
attribute in sysfs anymore.  It is replaced with a queue attribute which
also is writable for easier testing.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Reviewed-by: Johannes Thumshirn 
Signed-off-by: Jens Axboe

block: lift setting the readahead size into the block layer

2020-09-24T19:43:39+00:00

Drivers shouldn't really mess with the readahead size, as that is a VM
concept.  Instead set it based on the optimal I/O size by lifting the
algorithm from the md driver when registering the disk.  Also set
bdi->io_pages there as well by applying the same scheme based on
max_sectors.  To ensure the limits work well for stacking drivers a
new helper is added to update the readahead limits from the block
limits, which is also called from disk_stack_limits.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Reviewed-by: Jan Kara 
Reviewed-by: Mike Snitzer 
Reviewed-by: Martin K. Petersen 
Acked-by: Coly Li 
Signed-off-by: Jens Axboe