refcount_t is not as expensive as it used to be, but it's still more
expensive than the io_uring method of using atomic_t and just checking
for potential over/underflow.

This borrows that same implementation, which in turn is based on the
mm implementation from Linus.
Reviewed-by: NKeith Busch <kbusch@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Just use the disk attached to the request_queue instead.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NChaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20211126121802.2090656-4-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Remove the ioc argument as it always points to current->io_context.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-15-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Move blk_mq_sched_assign_ioc so that many interfaces from the file can
be marked static.  Rename the function to ioc_find_get_icq as well and
return the icq to simplify the interface.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-8-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Not needed, shift it into the source files that need it instead.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-9-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Not needed.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-8-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Not needed.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-7-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

No needed, shift a blk-stat.h include into the source file that needs it
instead.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-6-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

No needed, shift it into the source files that need it instead.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-5-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

All callers pass q->elevator.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-4-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Open code elevator_exit in it's only caller, and rename __elevator_exit to
elevator_exit.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-3-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

blk_get_flush_queue is only used in blk-flush.c, so move it there.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-2-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

blk_mq_submit_bio has two different plug cases, one that uses full
plugging and a limited plugging one.

The limited plugging case is only used for a corner case that does
not matter in real life:

 - no ->commit_rqs (so not NVMe)
 - no shared tags (so not SCSI)
 - not rotational (so no old disk or floppy driver)
 - must have multiple queues (so no eMMC)

Remove the limited merging case and all the related junk to simplify
blk_mq_submit_bio and the functions called from it.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123160443.1315598-2-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Unify the functionality that implements a partition rescan for a
gendisk.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-6-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

This function is only used by the request completion path.  Factor out
a blk_status_to_str to keep blk_errors private in blk-core.c.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NChaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-11-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

These are only used for request based I/O, so move them where they are
used.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-9-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Keep all the request based code together.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-6-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

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: NYi 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: NMing Lei <ming.lei@redhat.com>
Reviewed-by: NBart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20211118153041.2163228-1-ming.lei@redhat.comSigned-off-by: NJens 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: NChristoph Hellwig <hch@lst.de>
[axboe: update to check merge post submit_bio_checks() doing remap...]
Signed-off-by: NJens 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: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens 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: NDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NKeith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20211027022223.183838-2-damien.lemoal@wdc.comSigned-off-by: NJens 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: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211019122553.2467817-1-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Instead of returning the same queue request through a request pointer,
use a boolean to accomplish the same.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens 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: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens 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: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens 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: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Reviewed-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Tested-by: NMark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-12-hch@lst.deSigned-off-by: NJens 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: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b0662a636bd4cc7b4f84c9d0a41efa46a688ef13.1633781740.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Simplify the ioctl path and match the code structure on the compat side.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012104450.659013-4-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

These are only used inside of block/.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012104450.659013-3-hch@lst.deSigned-off-by: NJens 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: NJens 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: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens 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: NJohn Garry <john.garry@huawei.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/1633429419-228500-7-git-send-email-john.garry@huawei.comSigned-off-by: NJens 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: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-16-hch@lst.deSigned-off-by: NJens 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: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-13-hch@lst.deSigned-off-by: NJens 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: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Tested-by: NDarrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20210929071241.934472-6-hch@lst.deTested-by: NYi Zhang <yi.zhang@redhat.com>
Signed-off-by: NJens 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: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Tested-by: NDarrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20210929071241.934472-5-hch@lst.deTested-by: NYi Zhang <yi.zhang@redhat.com>
Signed-off-by: NJens 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: NChristoph 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: NJens 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: NKeith Busch <kbusch@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Prepare for proper error handling in add_disk.
Signed-off-by: NLuis Chamberlain <mcgrof@kernel.org>
[hch: split from a larger patch]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-9-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Prepare for proper error handling in add_disk.
Signed-off-by: NLuis Chamberlain <mcgrof@kernel.org>
[hch: split from a larger patch]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-8-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>