Commit adc0daad ("dm: report suspended
device during destroy") broke integrity recalculation.

The problem is dm_suspended() returns true not only during suspend,
but also during resume. So this race condition could occur:
1. dm_integrity_resume calls queue_work(ic->recalc_wq, &ic->recalc_work)
2. integrity_recalc (&ic->recalc_work) preempts the current thread
3. integrity_recalc calls if (unlikely(dm_suspended(ic->ti))) goto unlock_ret;
4. integrity_recalc exits and no recalculating is done.

To fix this race condition, add a function dm_post_suspending that is
only true during the postsuspend phase and use it instead of
dm_suspended().

Signed-off-by: Mikulas Patocka <mpatocka redhat com>
Fixes: adc0daad ("dm: report suspended device during destroy")
Cc: stable vger kernel org # v4.18+
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

kobject_uevent may allocate memory and it may be called while there are dm
devices suspended. The allocation may recurse into a suspended device,
causing a deadlock. We must set the noio flag when sending a uevent.

The observed deadlock was reported here:
https://www.redhat.com/archives/dm-devel/2020-March/msg00025.htmlReported-by: NKhazhismel Kumykov <khazhy@google.com>
Reported-by: NTahsin Erdogan <tahsin@google.com>
Reported-by: NGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

bio_uninit is the proper API to clean up a BIO that has been allocated
on stack or inside a structure that doesn't come from the BIO allocator.
Switch dm to use that instead of bio_disassociate_blkg, which really is
an implementation detail.  Note that the bio_uninit calls are also moved
to the two callers of __send_empty_flush, so that they better pair with
the bio_init calls used to initialize them.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Given request-based DM now uses blk-mq's blk_mq_queue_inflight() to
determine if outstanding IO has completed (and DM has no control over
the blk-mq state machine used to track outstanding IO) it is unsafe to
wakeup waiter (dm_wait_for_completion) before blk-mq has cleared a
request's state bits (e.g. MQ_RQ_IN_FLIGHT or MQ_RQ_COMPLETE).  As
such dm_wait_for_completion() could be left to wait indefinitely if no
other requests complete.

Fix this by eliminating request-based DM's use of waitqueue to wait
for blk-mq requests to complete in dm_wait_for_completion.
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Depends-on: 3c94d83c ("blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight()")
Cc: stable@vger.kernel.org
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Naohiro reported that issuing zone-append bios to a zoned block device
underneath a dm-linear device does not work as expected.

This because we forgot to reverse-map the sector the device wrote to the
original bio.

For zone-append bios, get the offset in the zone of the written sector
from the clone bio and add that to the original bio's sector position.

Fixes: 0512a75b ("block: Introduce REQ_OP_ZONE_APPEND")
Cc: stable@vger.kernel.org
Reported-by: NNaohiro Aota <Naohiro.Aota@wdc.com>
Signed-off-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Switch dm to use the nicer bio accounting helpers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Now that DMDEBUG uses pr_debug and DMDEBUG_LIMIT uses
pr_debug_ratelimited cleanup DM's 2 direct pr_debug callers to use
them to get the benefit of consistent DM_FMT formatting of debugging
messages.

While doing so, dm-mpath.c:dm_report_EIO() was switched over to using
DMDEBUG_LIMIT due to the potential for error handling floods in the IO
completion path.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

blk_mq_make_request currently needs to grab an q_usage_counter
reference when allocating a request.  This is because the block layer
grabs one before calling blk_mq_make_request, but also releases it as
soon as blk_mq_make_request returns.  Remove the blk_queue_exit call
after blk_mq_make_request returns, and instead let it consume the
reference.  This works perfectly fine for the block layer caller, just
device mapper needs an extra reference as the old problem still
persists there.  Open code blk_queue_enter_live in device mapper,
as there should be no other callers and this allows better documenting
why we do a non-try get.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The HST path selector needs this information to perform path
prediction. For request-based mpath, struct request's io_start_time_ns
is used, while for bio-based, use the start_time stored in dm_io.
Signed-off-by: NGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

We must have some way of letting a storage device driver know what
encryption context it should use for en/decrypting a request. However,
it's the upper layers (like the filesystem/fscrypt) that know about and
manages encryption contexts. As such, when the upper layer submits a bio
to the block layer, and this bio eventually reaches a device driver with
support for inline encryption, the device driver will need to have been
told the encryption context for that bio.

We want to communicate the encryption context from the upper layer to the
storage device along with the bio, when the bio is submitted to the block
layer. To do this, we add a struct bio_crypt_ctx to struct bio, which can
represent an encryption context (note that we can't use the bi_private
field in struct bio to do this because that field does not function to pass
information across layers in the storage stack). We also introduce various
functions to manipulate the bio_crypt_ctx and make the bio/request merging
logic aware of the bio_crypt_ctx.

We also make changes to blk-mq to make it handle bios with encryption
contexts. blk-mq can merge many bios into the same request. These bios need
to have contiguous data unit numbers (the necessary changes to blk-merge
are also made to ensure this) - as such, it suffices to keep the data unit
number of just the first bio, since that's all a storage driver needs to
infer the data unit number to use for each data block in each bio in a
request. blk-mq keeps track of the encryption context to be used for all
the bios in a request with the request's rq_crypt_ctx. When the first bio
is added to an empty request, blk-mq will program the encryption context
of that bio into the request_queue's keyslot manager, and store the
returned keyslot in the request's rq_crypt_ctx. All the functions to
operate on encryption contexts are in blk-crypto.c.

Upper layers only need to call bio_crypt_set_ctx with the encryption key,
algorithm and data_unit_num; they don't have to worry about getting a
keyslot for each encryption context, as blk-mq/blk-crypto handles that.
Blk-crypto also makes it possible for request-based layered devices like
dm-rq to make use of inline encryption hardware by cloning the
rq_crypt_ctx and programming a keyslot in the new request_queue when
necessary.

Note that any user of the block layer can submit bios with an
encryption context, such as filesystems, device-mapper targets, etc.
Signed-off-by: NSatya Tangirala <satyat@google.com>
Reviewed-by: NEric Biggers <ebiggers@google.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Call blk_mq_make_request when no ->make_request_fn is set.  This is
safe now that blk_alloc_queue always sets up the pointer for make_request
based drivers.  This avoids an indirect call in the blk-mq driver I/O
fast path, which is rather expensive due to spectre mitigations.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This reverts commit effd58c9.

blk_queue_split() is causing excessive IO splitting -- because
blk_max_size_offset() depends on 'chunk_sectors' limit being set and
if it isn't (as is the case for DM targets!) it falls back to
splitting on a 'max_sectors' boundary regardless of offset.

"Fix" this by reverting back to _not_ using blk_queue_split() in
dm_process_bio() for normal IO (reads and writes).  Long-term fix is
still TBD but it should focus on training blk_max_size_offset() to
call into a DM provided hook (to call DM's max_io_len()).

Test results from simple misaligned IO test on 4-way dm-striped device
with chunksize of 128K and stripesize of 512K:

xfs_io -d -c 'pread -b 2m 224s 4072s' /dev/mapper/stripe_dev

before this revert:

253,0   21        1     0.000000000  2206  Q   R 224 + 4072 [xfs_io]
253,0   21        2     0.000008267  2206  X   R 224 / 480 [xfs_io]
253,0   21        3     0.000010530  2206  X   R 224 / 256 [xfs_io]
253,0   21        4     0.000027022  2206  X   R 480 / 736 [xfs_io]
253,0   21        5     0.000028751  2206  X   R 480 / 512 [xfs_io]
253,0   21        6     0.000033323  2206  X   R 736 / 992 [xfs_io]
253,0   21        7     0.000035130  2206  X   R 736 / 768 [xfs_io]
253,0   21        8     0.000039146  2206  X   R 992 / 1248 [xfs_io]
253,0   21        9     0.000040734  2206  X   R 992 / 1024 [xfs_io]
253,0   21       10     0.000044694  2206  X   R 1248 / 1504 [xfs_io]
253,0   21       11     0.000046422  2206  X   R 1248 / 1280 [xfs_io]
253,0   21       12     0.000050376  2206  X   R 1504 / 1760 [xfs_io]
253,0   21       13     0.000051974  2206  X   R 1504 / 1536 [xfs_io]
253,0   21       14     0.000055881  2206  X   R 1760 / 2016 [xfs_io]
253,0   21       15     0.000057462  2206  X   R 1760 / 1792 [xfs_io]
253,0   21       16     0.000060999  2206  X   R 2016 / 2272 [xfs_io]
253,0   21       17     0.000062489  2206  X   R 2016 / 2048 [xfs_io]
253,0   21       18     0.000066133  2206  X   R 2272 / 2528 [xfs_io]
253,0   21       19     0.000067507  2206  X   R 2272 / 2304 [xfs_io]
253,0   21       20     0.000071136  2206  X   R 2528 / 2784 [xfs_io]
253,0   21       21     0.000072764  2206  X   R 2528 / 2560 [xfs_io]
253,0   21       22     0.000076185  2206  X   R 2784 / 3040 [xfs_io]
253,0   21       23     0.000077486  2206  X   R 2784 / 2816 [xfs_io]
253,0   21       24     0.000080885  2206  X   R 3040 / 3296 [xfs_io]
253,0   21       25     0.000082316  2206  X   R 3040 / 3072 [xfs_io]
253,0   21       26     0.000085788  2206  X   R 3296 / 3552 [xfs_io]
253,0   21       27     0.000087096  2206  X   R 3296 / 3328 [xfs_io]
253,0   21       28     0.000093469  2206  X   R 3552 / 3808 [xfs_io]
253,0   21       29     0.000095186  2206  X   R 3552 / 3584 [xfs_io]
253,0   21       30     0.000099228  2206  X   R 3808 / 4064 [xfs_io]
253,0   21       31     0.000101062  2206  X   R 3808 / 3840 [xfs_io]
253,0   21       32     0.000104956  2206  X   R 4064 / 4096 [xfs_io]
253,0   21       33     0.001138823     0  C   R 4096 + 200 [0]

after this revert:

253,0   18        1     0.000000000  4430  Q   R 224 + 3896 [xfs_io]
253,0   18        2     0.000018359  4430  X   R 224 / 256 [xfs_io]
253,0   18        3     0.000028898  4430  X   R 256 / 512 [xfs_io]
253,0   18        4     0.000033535  4430  X   R 512 / 768 [xfs_io]
253,0   18        5     0.000065684  4430  X   R 768 / 1024 [xfs_io]
253,0   18        6     0.000091695  4430  X   R 1024 / 1280 [xfs_io]
253,0   18        7     0.000098494  4430  X   R 1280 / 1536 [xfs_io]
253,0   18        8     0.000114069  4430  X   R 1536 / 1792 [xfs_io]
253,0   18        9     0.000129483  4430  X   R 1792 / 2048 [xfs_io]
253,0   18       10     0.000136759  4430  X   R 2048 / 2304 [xfs_io]
253,0   18       11     0.000152412  4430  X   R 2304 / 2560 [xfs_io]
253,0   18       12     0.000160758  4430  X   R 2560 / 2816 [xfs_io]
253,0   18       13     0.000183385  4430  X   R 2816 / 3072 [xfs_io]
253,0   18       14     0.000190797  4430  X   R 3072 / 3328 [xfs_io]
253,0   18       15     0.000197667  4430  X   R 3328 / 3584 [xfs_io]
253,0   18       16     0.000218751  4430  X   R 3584 / 3840 [xfs_io]
253,0   18       17     0.000226005  4430  X   R 3840 / 4096 [xfs_io]
253,0   18       18     0.000250404  4430  Q   R 4120 + 176 [xfs_io]
253,0   18       19     0.000847708     0  C   R 4096 + 24 [0]
253,0   18       20     0.000855783     0  C   R 4120 + 176 [0]

Fixes: effd58c9 ("dm: always call blk_queue_split() in dm_process_bio()")
Cc: stable@vger.kernel.org
Reported-by: NAndreas Gruenbacher <agruenba@redhat.com>
Tested-by: NBarry Marson <bmarson@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

zero_page_range() dax operation is mandatory for dax devices. Right now
that check happens in dax_zero_page_range() function. Dan thinks that's
too late and its better to do the check earlier in alloc_dax().

I also modified alloc_dax() to return pointer with error code in it in
case of failure. Right now it returns NULL and caller assumes failure
happened due to -ENOMEM. But with this ->zero_page_range() check, I
need to return -EINVAL instead.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20200401161125.GB9398@redhat.comSigned-off-by: NDan Williams <dan.j.williams@intel.com>

This patch adds support for dax zero_page_range operation to dm targets.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20200228163456.1587-5-vgoyal@redhat.comSigned-off-by: NDan Williams <dan.j.williams@intel.com>

Current make_request based drivers use either blk_alloc_queue_node or
blk_alloc_queue to allocate a queue, and then set up the make_request_fn
function pointer and a few parameters using the blk_queue_make_request
helper.  Simplify this by passing the make_request pointer to
blk_alloc_queue, and while at it merge the _node variant into the main
helper by always passing a node_id, and remove the superfluous gfp_mask
parameter.  A lower-level __blk_alloc_queue is kept for the blk-mq case.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

These macros are just used by a few files.  Move them out of genhd.h,
which is included everywhere into a new standalone header.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We neither assign congested_fn for requested-based blk-mq device nor
implement it correctly. So fix both.

Also, remove incorrect comment from dm_init_normal_md_queue and rename
it to dm_init_congested_fn.

Fixes: 4aa9c692 ("bdi: separate out congested state into a separate struct")
Cc: stable@vger.kernel.org
Signed-off-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

The function dm_suspended returns true if the target is suspended.
However, when the target is being suspended during unload, it returns
false.

An example where this is a problem: the test "!dm_suspended(wc->ti)" in
writecache_writeback is not sufficient, because dm_suspended returns
zero while writecache_suspend is in progress.  As is, without an
enhanced dm_suspended, simply switching from flush_workqueue to
drain_workqueue still emits warnings:
workqueue writecache-writeback: drain_workqueue() isn't complete after 10 tries
workqueue writecache-writeback: drain_workqueue() isn't complete after 100 tries
workqueue writecache-writeback: drain_workqueue() isn't complete after 200 tries
workqueue writecache-writeback: drain_workqueue() isn't complete after 300 tries
workqueue writecache-writeback: drain_workqueue() isn't complete after 400 tries

writecache_suspend calls flush_workqueue(wc->writeback_wq) - this function
flushes the current work. However, the workqueue may re-queue itself and
flush_workqueue doesn't wait for re-queued works to finish. Because of
this - the function writecache_writeback continues execution after the
device was suspended and then concurrently with writecache_dtr, causing
a crash in writecache_writeback.

We must use drain_workqueue - that waits until the work and all re-queued
works finish.

As a prereq for switching to drain_workqueue, this commit fixes
dm_suspended to return true after the presuspend hook and before the
postsuspend hook - just like during a normal suspend. It allows
simplifying the dm-integrity and dm-writecache targets so that they
don't have to maintain suspended flags on their own.

With this change use of drain_workqueue() can be used effectively.  This
change was tested with the lvm2 testsuite and cryptsetup testsuite and
the are no regressions.

Fixes: 48debafe ("dm: add writecache target")
Cc: stable@vger.kernel.org # 4.18+
Reported-by: NCorey Marthaler <cmarthal@redhat.com>
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Move blk_queue_make_request() to dm.c:alloc_dev() so that
q->make_request_fn is never NULL during the lifetime of a DM device
(even one that is created without a DM table).

Otherwise generic_make_request() will crash simply by doing:
  dmsetup create -n test
  mount /dev/dm-N /mnt

While at it, move ->congested_data initialization out of
dm.c:alloc_dev() and into the bio-based specific init method.
Reported-by: NStefan Bader <stefan.bader@canonical.com>
BugLink: https://bugs.launchpad.net/bugs/1860231
Fixes: ff36ab34 ("dm: remove request-based logic from make_request_fn wrapper")
Depends-on: c12c9a3c ("dm: various cleanups to md->queue initialization code")
Cc: stable@vger.kernel.org
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Avoid the need to allocate a potentially large array of struct blk_zone
in the block layer by switching the ->report_zones method interface to
a callback model. Now the caller simply supplies a callback that is
executed on each reported zone, and private data for it.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NShin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

No known partitioning tool supports zoned block devices, especially the
host managed flavor with strong sequential write constraints.
Furthermore, there are also no known user nor use cases for partitioned
zoned block devices.

This patch removes partition device creation for zoned block devices,
which allows simplifying the processing of zone commands for zoned
block devices. A warning is added if a partition table is found on the
device.

For report zones operations no zone sector information remapping is
necessary anymore, simplifying the code. Of note is that remapping of
zone reports for DM targets is still necessary as done by
dm_remap_zone_report().

Similarly, remaping of a zone reset bio is not necessary anymore.
Testing for the applicability of the zone reset all request also becomes
simpler and only needs to check that the number of sectors of the
requested zone range is equal to the disk capacity.
Reviewed-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

All kernel users of blkdev_report_zones() as well as applications use
through ioctl(BLKZONEREPORT) expect to potentially get less zone
descriptors than requested. As such, the use of the internal report
zones command execution loop implemented by blk_report_zones() is
not necessary and can even be harmful to performance by causing the
execution of inefficient small zones report command to service the
reminder of a requested zone array.

This patch removes blk_report_zones(), simplifying the code. Also
remove a now incorrect comment in dm_blk_report_zones().
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJavier Gonzalez <javier@javigon.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Implement REQ_OP_ZONE_OPEN, REQ_OP_ZONE_CLOSE and REQ_OP_ZONE_FINISH
support to allow explicit control of zone states.

Contains contributions from Matias Bjorling, Hans Holmberg and
Damien Le Moal.
Acked-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAjay Joshi <ajay.joshi@wdc.com>
Signed-off-by: NMatias Bjorling <matias.bjorling@wdc.com>
Signed-off-by: NHans Holmberg <hans.holmberg@wdc.com>
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Currently, if we pass too high sector number to dm_table_find_target, it
returns zeroed dm_target structure and callers test if the structure is
zeroed with the macro dm_target_is_valid.

However, returning NULL is common practice to indicate errors.

This patch refactors the dm code, so that dm_table_find_target returns
NULL and its callers test the returned value for NULL. The macro
dm_target_is_valid is deleted. In alloc_targets, we no longer allocate an
extra zeroed target.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Only GFP_KERNEL and GFP_NOIO are used with blkdev_report_zones(). In
preparation of using vmalloc() for large report buffer and zone array
allocations used by this function, remove its "gfp_t gfp_mask" argument
and rely on the caller context to use memalloc_noio_save/restore() where
necessary (block layer zone revalidation and dm-zoned I/O error path).
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch sets dax device 'DAXDEV_SYNC' flag if all the target
devices of device mapper support synchrononous DAX. If device
mapper consists of both synchronous and asynchronous dax devices,
we don't set 'DAXDEV_SYNC' flag.

'dm_table_supports_dax' is refactored to pass 'iterate_devices_fn'
as argument so that the callers can pass the appropriate functions.
Suggested-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NPankaj Gupta <pagupta@redhat.com>
Reviewed-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

This patch adds 'DAXDEV_SYNC' flag which is set
for nd_region doing synchronous flush. This later
is used to disable MAP_SYNC functionality for
ext4 & xfs filesystem for devices don't support
synchronous flush.
Signed-off-by: NPankaj Gupta <pagupta@redhat.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Commit 61697a6a ("dm: eliminate 'split_discard_bios' flag from DM
target interface") incorrectly removed code from
__send_changing_extent_only() that is required to impose a per-target IO
boundary on IO that exceeds max_io_len_target_boundary().  Otherwise
"special" IO (e.g. DISCARD, WRITE SAME, WRITE ZEROES) can write beyond
where allowed.

Fix this by restoring the max_io_len_target_boundary() limit in
__send_changing_extent_only()

Fixes: 61697a6a ("dm: eliminate 'split_discard_bios' flag from DM target interface")
Cc: stable@vger.kernel.org # 5.1+
Signed-off-by: NMichael Lass <bevan@bi-co.net>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Pankaj reports that starting with commit ad428cdb "dax: Check the
end of the block-device capacity with dax_direct_access()" device-mapper
no longer allows dax operation. This results from the stricter checks in
__bdev_dax_supported() that validate that the start and end of a
block-device map to the same 'pagemap' instance.

Teach the dax-core and device-mapper to validate the 'pagemap' on a
per-target basis. This is accomplished by refactoring the
bdev_dax_supported() internals into generic_fsdax_supported() which
takes a sector range to validate. Consequently generic_fsdax_supported()
is suitable to be used in a device-mapper ->iterate_devices() callback.
A new ->dax_supported() operation is added to allow composite devices to
split and route upper-level bdev_dax_supported() requests.

Fixes: ad428cdb ("dax: Check the end of the block-device...")
Cc: <stable@vger.kernel.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Reported-by: NPankaj Gupta <pagupta@redhat.com>
Reviewed-by: NPankaj Gupta <pagupta@redhat.com>
Tested-by: NPankaj Gupta <pagupta@redhat.com>
Tested-by: NVaibhav Jain <vaibhav@linux.ibm.com>
Reviewed-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Signed-off-by: NSheetal Singala <2396sheetal@gmail.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

md->dax_dev defaults to NULL and there is no need to initialize it
if CONFIG_DAX_DRIVER is disabled.
Signed-off-by: NPeng Wang <rocking@whu.edu.cn>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Storage devices which report supporting discard commands like
WRITE_SAME_16 with unmap, but reject discard commands sent to the
storage device.  This is a clear storage firmware bug but it doesn't
change the fact that should a program cause discards to be sent to a
multipath device layered on this buggy storage, all paths can end up
failed at the same time from the discards, causing possible I/O loss.

The first discard to a path will fail with Illegal Request, Invalid
field in cdb, e.g.:
 kernel: sd 8:0:8:19: [sdfn] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
 kernel: sd 8:0:8:19: [sdfn] tag#0 Sense Key : Illegal Request [current]
 kernel: sd 8:0:8:19: [sdfn] tag#0 Add. Sense: Invalid field in cdb
 kernel: sd 8:0:8:19: [sdfn] tag#0 CDB: Write same(16) 93 08 00 00 00 00 00 a0 08 00 00 00 80 00 00 00
 kernel: blk_update_request: critical target error, dev sdfn, sector 10487808

The SCSI layer converts this to the BLK_STS_TARGET error number, the sd
device disables its support for discard on this path, and because of the
BLK_STS_TARGET error multipath fails the discard without failing any
path or retrying down a different path.  But subsequent discards can
cause path failures.  Any discards sent to the path which already failed
a discard ends up failing with EIO from blk_cloned_rq_check_limits with
an "over max size limit" error since the discard limit was set to 0 by
the sd driver for the path.  As the error is EIO, this now fails the
path and multipath tries to send the discard down the next path.  This
cycle continues as discards are sent until all paths fail.

Fix this by training DM core to disable DISCARD if the underlying
storage already did so.

Also, fix branching in dm_done() and clone_endio() to reflect the
mutually exclussive nature of the IO operations in question.

Cc: stable@vger.kernel.org
Reported-by: NDavid Jeffery <djeffery@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

The limit was already incorporated to dm-crypt with commit 4e870e94
("dm crypt: fix error with too large bios"), so we don't need to apply
it globally to all targets. The quantity BIO_MAX_PAGES * PAGE_SIZE is
wrong anyway because the variable ti->max_io_len it is supposed to be in
the units of 512-byte sectors not in bytes.

Reduction of the limit to 1048576 sectors could even cause data
corruption in rare cases - suppose that we have a dm-striped device with
stripe size 768MiB. The target will call dm_set_target_max_io_len with
the value 1572864. The buggy code would reduce it to 1048576. Now, the
dm-core will errorneously split the bios on 1048576-sector boundary
insetad of 1572864-sector boundary and pass these stripe-crossing bios
to the striped target.

Cc: stable@vger.kernel.org # v4.16+
Fixes: 8f50e358 ("dm: limit the max bio size as BIO_MAX_PAGES * PAGE_SIZE")
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Acked-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Do not just call blk_queue_split() if the bio is_abnormal_io().

Fixes: 568c73a3 ("dm: update dm_process_bio() to split bio if in ->make_request_fn()")
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Also move dm_rq_target_io structure definition from dm-rq.h to dm-rq.c

Fixes: 6a23e05c ("dm: remove legacy request-based IO path")
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

There is no need to have DM core split discards on behalf of a DM target
now that blk_queue_split() handles splitting discards based on the
queue_limits.  A DM target just needs to set max_discard_sectors,
discard_granularity, etc, in queue_limits.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Must call blk_queue_split() otherwise queue_limits for abnormal requests
(e.g. discard, writesame, etc) won't be imposed.

In addition, add dm_queue_split() to simplify DM specific splitting that
is needed for targets that impose ti->max_io_len.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

bio_trim() has an early return, which makes it _not_ idempotent, if the
offset is 0 and the bio's bi_size already matches the requested size.
Prior to DM, all users of bio_trim() were fine with this.  But DM has
exposed the fact that bio_trim()'s early return is incompatible with a
cloned bio whose integrity payload must be trimmed via
bio_integrity_trim().

Fix this by reverting DM back to doing the equivalent of bio_trim() but
in an idempotent manner (so bio_integrity_trim is always performed).

Follow-on work is needed to assess what benefit bio_trim()'s early
return is providing to its existing callers.
Reported-by: NMilan Broz <gmazyland@gmail.com>
Fixes: 57c36519 ("dm: fix clone_bio() to trigger blk_recount_segments()")
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Block core changes to switch bio-based IO accounting to be percpu had a
side-effect of altering DM core to now rely on calling waitqueue_active
(in both bio-based and request-based) to check if another task is in
dm_wait_for_completion().

A memory barrier is needed before calling waitqueue_active().  DM core
doesn't piggyback on a preceding memory barrier so it must explicitly
use its own.

For more details on why using waitqueue_active() without a preceding
barrier is unsafe, please see the comment before the waitqueue_active()
definition in include/linux/wait.h.

Add the missing memory barrier by switching to using wq_has_sleeper().

Fixes: 6f757231 ("dm: remove the pending IO accounting")
Fixes: c4576aed ("dm: fix request-based dm's use of dm_wait_for_completion")
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Provides useful context about bio splits in blktrace.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>