We never insert flush request into scheduler queue before.

Recently commit d92ca9d8 ("blk-mq: don't handle non-flush requests in
blk_insert_flush") tries to handle FUA data request as normal request.
This way has caused warning[1] in mq-deadline dd_exit_sched() or io hang in
case of kyber since RQF_ELVPRIV isn't set for flush request, then
->finish_request won't be called.

Fix the issue by inserting FUA data request with blk_mq_request_bypass_insert()
when the device supports FUA, just like what we did before.

[1] https://lore.kernel.org/linux-block/CAHj4cs-_vkTW=dAzbZYGxpEWSpzpcmaNeY1R=vH311+9vMUSdg@mail.gmail.com/



Reported-by: Yi Zhang <yi.zhang@redhat.com>
Fixes: d92ca9d8 ("blk-mq: don't handle non-flush requests in blk_insert_flush")
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20211118153041.2163228-1-ming.lei@redhat.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Retain the old logic for the fops based submit, but for our internal
blk_mq_submit_bio(), move the queue entering logic into the core
function itself.

We need to be a bit careful if going into the scheduler, as a scheduler
or queue mappings can arbitrarily change before we have entered the queue.
Have the bio scheduler mapping do that separately, it's a very cheap
operation compared to actually doing merging locking and lookups.

Reviewed-by: Christoph Hellwig <hch@lst.de>
[axboe: update to check merge post submit_bio_checks() doing remap...]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Just a prep patch for shifting the queue enter logic. This moves the
expected fast path inline, and leaves __bio_queue_enter() as an
out-of-line function call. We don't want to inline the latter, as it's
mostly slow path code.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The Concurrent Positioning Ranges VPD page (for SCSI) and data log page
(for ATA) contain parameters describing the set of contiguous LBAs that
can be served independently by a single LUN multi-actuator hard-disk.
Similarly, a logically defined block device composed of multiple disks
can in some cases execute requests directed at different sector ranges
in parallel. A dm-linear device aggregating 2 block devices together is
an example.

This patch implements support for exposing a block device independent
access ranges to the user through sysfs to allow optimizing device
accesses to increase performance.

To describe the set of independent sector ranges of a device (actuators
of a multi-actuator HDDs or table entries of a dm-linear device),
The type struct blk_independent_access_ranges is introduced. This
structure describes the sector ranges using an array of
struct blk_independent_access_range structures. This range structure
defines the start sector and number of sectors of the access range.
The ranges in the array cannot overlap and must contain all sectors
within the device capacity.

The function disk_set_independent_access_ranges() allows a device
driver to signal to the block layer that a device has multiple
independent access ranges.  In this case, a struct
blk_independent_access_ranges is attached to the device request queue
by the function disk_set_independent_access_ranges(). The function
disk_alloc_independent_access_ranges() is provided for drivers to
allocate this structure.

struct blk_independent_access_ranges contains kobjects (struct kobject)
to expose to the user through sysfs the set of independent access ranges
supported by a device. When the device is initialized, sysfs
registration of the ranges information is done from blk_register_queue()
using the block layer internal function
disk_register_independent_access_ranges(). If a driver calls
disk_set_independent_access_ranges() for a registered queue, e.g. when a
device is revalidated, disk_set_independent_access_ranges() will execute
disk_register_independent_access_ranges() to update the sysfs attribute
files.  The sysfs file structure created starts from the
independent_access_ranges sub-directory and contains the start sector
and number of sectors of each range, with the information for each range
grouped in numbered sub-directories.

E.g. for a dual actuator HDD, the user sees:

$ tree /sys/block/sdk/queue/independent_access_ranges/
/sys/block/sdk/queue/independent_access_ranges/
|-- 0
|   |-- nr_sectors
|   `-- sector
`-- 1
    |-- nr_sectors
    `-- sector

For a regular device with a single access range, the
independent_access_ranges sysfs directory does not exist.

Device revalidation may lead to changes to this structure and to the
attribute values. When manipulated, the queue sysfs_lock and
sysfs_dir_lock mutexes are held for atomicity, similarly to how the
blk-mq and elevator sysfs queue sub-directories are protected.

The code related to the management of independent access ranges is
added in the new file block/blk-ia-ranges.c.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20211027022223.183838-2-damien.lemoal@wdc.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Return to the normal blk_mq_submit_bio flow if the bio did not end up
actually being a flush because the device didn't support it.  Note that
this is basically impossible to hit without special instrumentation given
that submit_bio_checks already clears these flags usually, so we'd need a
tight race to actually hit this code path.

With this the call to blk_mq_run_hw_queue for the flush requests can be
removed given that the actual flush requests are always issued via the
requeue workqueue which runs the queue unconditionally.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211019122553.2467817-1-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Instead of returning the same queue request through a request pointer,
use a boolean to accomplish the same.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

For some reason we still have them in blk-core, with the rest of the
request completion being in blk-mq. That causes and out-of-line call
for each completion.

Move them into blk-mq.c instead, where they belong.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The fast path is no splitting needed. Separate the handling into a
check part we can inline, and an out-of-line handling path if we do
need to split.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Unlike the RWF_HIPRI userspace ABI which is intentionally kept vague,
the bio flag is specific to the polling implementation, so rename and
document it properly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-12-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Extract hot paths of __blk_account_io_start() and
__blk_account_io_done() into inline functions, so we don't always pay
for function calls.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b0662a636bd4cc7b4f84c9d0a41efa46a688ef13.1633781740.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Simplify the ioctl path and match the code structure on the compat side.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012104450.659013-4-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

These are only used inside of block/.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012104450.659013-3-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Particularly for NVMe with efficient deferred submission for many
requests, there are nice benefits to be seen by bumping the default max
plug count from 16 to 32. This is especially true for virtualized setups,
where the submit part is more expensive. But can be noticed even on
native hardware.

Reduce the multiple queue factor from 4 to 2, since we're changing the
default size.

While changing it, move the defines into the block layer private header.
These aren't values that anyone outside of the block layer uses, or
should use.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Even if no policies are defined, we spend ~2% of the total IO time
checking. Move the fast path inline.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

To be more concise and consistent in naming, rename
blk_mq_sched_free_requests() -> blk_mq_sched_free_rqs().

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/1633429419-228500-7-git-send-email-john.garry@huawei.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>

These are block-layer internal helpers, so move them to block/blk.h and
block/blk-merge.c.  Also update a comment a bit to use better grammar.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-16-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Except for the features passed to blk_queue_required_elevator_features,
elevator.h is only needed internally to the block layer.  Move the
ELEVATOR_F_* definitions to blkdev.h, and the move elevator.h to
block/, dropping all the spurious includes outside of that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-13-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Don't switch back to percpu mode to avoid the double RCU grace period
when tearing down SCSI devices.  After removing the disk only passthrough
commands can be send anyway.

Suggested-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20210929071241.934472-6-hch@lst.de


Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Instead of delaying draining of file system I/O related items like the
blk-qos queues, the integrity read workqueue and timeouts only when the
request_queue is removed, do that when del_gendisk is called.  This is
important for SCSI where the upper level drivers that control the gendisk
are separate entities, and the disk can be freed much earlier than the
request_queue, or can even be unbound without tearing down the queue.

Fixes: edb0872f ("block: move the bdi from the request_queue to the gendisk")
Reported-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20210929071241.934472-5-hch@lst.de


Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add a new block/fops.c for all the file and address_space operations
that provide the block special file support.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210907141303.1371844-2-hch@lst.de


[axboe: correct trailing whitespace while at it]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Any case that turns off REQ_HIPRI must also clear BIO_PERCPU_CACHE,
as non-polled IO may complete through hard/soft IRQ and hence isn't
safe for our polled bio alloc cache.

Provide a helper that does just that, and use it in the merging code as
well if we split a bio and turn off polling.

Fixes: be863b9e ("block: clear BIO_PERCPU_CACHE flag if polling isn't supported")
Reported-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Prepare for proper error handling in add_disk.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-9-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Prepare for proper error handling in add_disk.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-8-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

is_flush_rq() is called from bt_iter()/bt_tags_iter(), and runs the
following check:

	hctx->fq->flush_rq == req

but the passed hctx from bt_iter()/bt_tags_iter() may be NULL because:

1) memory re-order in blk_mq_rq_ctx_init():

	rq->mq_hctx = data->hctx;
	...
	refcount_set(&rq->ref, 1);

OR

2) tag re-use and ->rqs[] isn't updated with new request.

Fix the issue by re-writing is_flush_rq() as:

	return rq->end_io == flush_end_io;

which turns out simpler to follow and immune to data race since we have
ordered WRITE rq->end_io and refcount_set(&rq->ref, 1).

Fixes: 2e315dc0 ("blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter")
Cc: "Blank-Burian, Markus, Dr." <blankburian@uni-muenster.de>
Cc: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210818010925.607383-1-ming.lei@redhat.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>

After patch 54efd50b (block: make generic_make_request handle
arbitrarily sized bios), the IO through io-throttle may be larger,
and these IOs may be further split into more small IOs. However,
IOPS throttle does not seem to be aware of this change, which
makes the calculation of IOPS of large IOs incomplete, resulting
in disk-side IOPS that does not meet expectations. Maybe we should
fix this problem.

We can reproduce it by set max_sectors_kb of disk to 128, set
blkio.write_iops_throttle to 100, run a dd instance inside blkio
and use iostat to watch IOPS:

dd if=/dev/zero of=/dev/sdb bs=1M count=1000 oflag=direct

As a result, without this change the average IOPS is 1995, with
this change the IOPS is 98.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/65869aaad05475797d63b4c3fed4f529febe3c26.1627876014.git.brookxu@tencent.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdev_resize_partition can only operate on the whole device.  Make that clear
by passing a gendisk instead of a block_device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210810154512.1809898-5-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdev_del_partition can only operate on the whole device.  Make that clear
by passing a gendisk instead of a block_device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210810154512.1809898-4-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdev_add_partition can only operate on the whole device.  Make that clear
by passing a gendisk instead of a block_device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210810154512.1809898-3-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Remove the disk_name function now that all users are gone.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210727062518.122108-7-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Lockdep complains about lock inversion between ioc->lock and bfqd->lock:

bfqd -> ioc:
 put_io_context+0x33/0x90 -> ioc->lock grabbed
 blk_mq_free_request+0x51/0x140
 blk_put_request+0xe/0x10
 blk_attempt_req_merge+0x1d/0x30
 elv_attempt_insert_merge+0x56/0xa0
 blk_mq_sched_try_insert_merge+0x4b/0x60
 bfq_insert_requests+0x9e/0x18c0 -> bfqd->lock grabbed
 blk_mq_sched_insert_requests+0xd6/0x2b0
 blk_mq_flush_plug_list+0x154/0x280
 blk_finish_plug+0x40/0x60
 ext4_writepages+0x696/0x1320
 do_writepages+0x1c/0x80
 __filemap_fdatawrite_range+0xd7/0x120
 sync_file_range+0xac/0xf0

ioc->bfqd:
 bfq_exit_icq+0xa3/0xe0 -> bfqd->lock grabbed
 put_io_context_active+0x78/0xb0 -> ioc->lock grabbed
 exit_io_context+0x48/0x50
 do_exit+0x7e9/0xdd0
 do_group_exit+0x54/0xc0

To avoid this inversion we change blk_mq_sched_try_insert_merge() to not
free the merged request but rather leave that upto the caller similarly
to blk_mq_sched_try_merge(). And in bfq_insert_requests() we make sure
to free all the merged requests after dropping bfqd->lock.

Fixes: aee69d78 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210623093634.27879-3-jack@suse.cz


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add the events attributes to the disk_attrs array, which ensures they are
added by the driver core when the device is created rather than adding
them after the device has been added, which is racy versus uevents and
requires more boilerplate code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210624073843.251178-3-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Move the code for handling disk events from genhd.c into a new file
as it isn't very related to the rest of the file while at the same
time requiring lots of forward declarations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210624073843.251178-2-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Don't return the passed in request_queue but a normal error code, and
drop the elevator_init argument in favor of just calling elevator_init_mq
directly from dm-rq.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Link: https://lore.kernel.org/r/20210602065345.355274-3-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk_alloc_queue is just an internal helper now, unexport it and remove
it from the public header.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-27-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Untangle the mess around blk_alloc_devt by moving the check for
the used allocation scheme into the callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-2-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Move the busy check and disk-wide sync into the only caller, so that
the remainder can be shared with del_gendisk.  Also pass the gendisk
instead of the bdev as that is all that is needed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-5-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Get rid of all the PFN arithmetics and just use an enum for the two
remaining options, and use PageHighMem for the actual bounce decision.

Add a fast path to entirely avoid the call for the common case of a queue
not using the legacy bouncing code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210331073001.46776-8-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Remove the BLK_BOUNCE_ISA support now that all users are gone.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210331073001.46776-7-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>

Introduce the internal function blk_queue_clear_zone_settings() to
cleanup all limits and resources related to zoned block devices. This
new function is called from blk_queue_set_zoned() when a disk zoned
model is set to BLK_ZONED_NONE. This particular case can happens when a
partition is created on a host-aware scsi disk.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@edc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Instead of encoding of the bvec pool using magic bio flags, just use
a helper to find the pool based on the max_vecs value.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>