blk-throttle: remove blk_throtl_drain

After the commit 5addeae1bedc4 ("blk-cgroup: remove blkcg_drain_queue"),
there is no caller of blk_throtl_drain, so let's remove it.

Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

null_blk: force complete for timeout request

The commit 7b11eab041da ("blk-mq: blk-mq: provide forced completion
method") exports new API to force a request to complete without error
injection.

There should be no error injection when completing a request by timeout
handler.

Otherwise, the below would hang because timeout handler is failed.

echo 100 > /sys/kernel/debug/fail_io_timeout/probability
echo 1000 > /sys/kernel/debug/fail_io_timeout/times
echo 1 > /sys/block/nullb0/io-timeout-fail
dd if=/dev/zero of=/dev/nullb0 bs=512 count=1 oflag=direct

With this patch, the timeout handler is able to complete the IO.

Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: drain I/O when all CPUs in a hctx are offline

Most of blk-mq drivers depend on managed IRQ's auto-affinity to setup
up queue mapping. Thomas mentioned the following point[1]:

"That was the constraint of managed interrupts from the very beginning:

 The driver/subsystem has to quiesce the interrupt line and the associated
 queue _before_ it gets shutdown in CPU unplug and not fiddle with it
 until it's restarted by the core when the CPU is plugged in again."

However, current blk-mq implementation doesn't quiesce hw queue before
the last CPU in the hctx is shutdown.  Even worse, CPUHP_BLK_MQ_DEAD is a
cpuhp state handled after the CPU is down, so there isn't any chance to
quiesce the hctx before shutting down the CPU.

Add new CPUHP_AP_BLK_MQ_ONLINE state to stop allocating from blk-mq hctxs
where the last CPU goes away, and wait for completion of in-flight
requests.  This guarantees that there is no inflight I/O before shutting
down the managed IRQ.

Add a BLK_MQ_F_STACKING and set it for dm-rq and loop, so we don't need
to wait for completion of in-flight requests from these drivers to avoid
a potential dead-lock. It is safe to do this for stacking drivers as those
do not use interrupts at all and their I/O completions are triggered by
underlying devices I/O completion.

[1] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@nanos.tec.linutronix.de/

[hch: different retry mechanism, merged two patches, minor cleanups]

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: add blk_mq_all_tag_iter

Add a new blk_mq_all_tag_iter function to iterate over all allocated
scheduler tags and driver tags.  This is more flexible than the existing
blk_mq_all_tag_busy_iter function as it allows the callers to do whatever
they want on allocated request instead of being limited to started
requests.

It will be used to implement draining allocated requests on specified
hctx in this patchset.

[hch: switch from the two booleans to a more readable flags field and
 consolidate the tags iter functions]

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Bart van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: open code __blk_mq_alloc_request in blk_mq_alloc_request_hctx

blk_mq_alloc_request_hctx is only used for NVMeoF connect commands, so
tailor it to the specific requirements, and don't bother the general
fast path code with its special twinkles.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: use BLK_MQ_NO_TAG in more places

Replace various magic -1 constants for tags with BLK_MQ_NO_TAG.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: rename BLK_MQ_TAG_FAIL to BLK_MQ_NO_TAG

To prepare for wider use of this constant give it a more applicable name.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: move more request initialization to blk_mq_rq_ctx_init

Don't split request initialization between __blk_mq_alloc_request and
blk_mq_rq_ctx_init.  Also remove the op argument as it can be derived
from the blk_mq_alloc_data structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: simplify the blk_mq_get_request calling convention

The bio argument is entirely unused, and the request_queue can be passed
through the alloc_data, given that it needs to be filled out for the
low-level tag allocation anyway.  Also rename the function to
__blk_mq_alloc_request as the switch between get and alloc in the call
chains is rather confusing.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: remove the bio argument to ->prepare_request

None of the I/O schedulers actually needs it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme: force complete cancelled requests

Use blk_mq_foce_complete_rq() to bypass fake timeout error injection so
that request reclaim may proceed.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: blk-mq: provide forced completion method

Drivers may need to bypass error injection for error recovery. Rename
__blk_mq_complete_request() to blk_mq_force_complete_rq() and export
that function so drivers may skip potential fake timeouts after they've
reclaimed lost requests.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: fix a warning when blkdev.h is included for !CONFIG_BLOCK builds

disk_start_io_acct and disk_end_io_acct need at least a struct gendisk
forward declaration, but for weird historic reasons much of blkdev.h
is stubbed out for CONFIG_BLOCK=n.  Fix this by stubbing more out for
now, but eventually this header will need a massive cleanup.

Fixes: 956d510ee78 ("block: add disk/bio-based accounting helpers")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: blk-crypto-fallback: remove redundant initialization of variable err

The variable err is being initialized with a value that is never read
and it is being updated later with a new value.  The initialization is
redundant and can be removed.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Satya Tangirala <satyat@google.com>
Addresses-Coverity: ("Unused value")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: reduce part_stat_lock() scope

We only need the stats lock (aka preempt_disable()) for updating the
states, not for looking up or dropping the hd_struct reference.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: use __this_cpu_add() instead of access by smp_processor_id()

Most architectures have fast path to access percpu for current cpu.
The required preempt_disable() is provided by part_stat_lock().

[hch: rebased]

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove rcu_read_lock() from part_stat_lock()

The RCU lock is required only in disk_map_sector_rcu() to lookup the
partition.  After that request holds reference to related hd_struct.

Replace get_cpu() with preempt_disable() - returned cpu index is unused.

[hch: rebased]

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add a blk_account_io_merge_bio helper

Move the non-"new_io" branch of blk_account_io_start() into separate
function.  Fix merge accounting for discards (they were counted as write
merges).

The new blk_account_io_merge_bio() doesn't call update_io_ticks() unlike
blk_account_io_start(), as there is no reason for that.

[hch: rebased]

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: account merge of two requests

Also rename blk_account_io_merge() into blk_account_io_merge_request() to
distinguish it from merging request and bio.

[hch: rebased]

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: always use a percpu variable for disk stats

percpu variables have a perfectly fine working stub implementation
for UP kernels, so use that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move update_io_ticks to blk-core.c

All callers are in blk-core.c, so move update_io_ticks over.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove generic_{start,end}_io_acct

Remove these now unused functions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

zram: nvdimm: use bio_{start,end}_io_acct and disk_{start,end}_io_acct

Switch zram to use the nicer bio accounting helpers, and as part of that
ensure each bio is counted as a single I/O request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvdimm: use bio_{start,end}_io_acct

Switch dm to use the nicer bio accounting helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

dm: use bio_{start,end}_io_acct

Switch dm to use the nicer bio accounting helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bcache: use bio_{start,end}_io_acct

Switch bcache to use the nicer bio accounting helpers, and call the
routines where we also sample the start time to give coherent accounting
results.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

lightnvm/pblk: use bio_{start,end}_io_acct

Switch rsxx to use the nicer bio accounting helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

rsxx: use bio_{start,end}_io_acct

Switch rsxx to use the nicer bio accounting helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drbd: use bio_{start,end}_io_acct

Switch drbd to use the nicer bio accounting helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add disk/bio-based accounting helpers

Add two new helpers to simplify I/O accounting for bio based drivers.
Currently these drivers use the generic_start_io_acct and
generic_end_io_acct helpers which have very cumbersome calling
conventions, don't actually return the time they started accounting,
and try to deal with accounting for partitions, which can't happen
for bio based drivers.  The new helpers will be used to subsequently
replace uses of the old helpers.

The main API is the bio based wrappes in blkdev.h, but for zram
which wants to account rw_page based I/O lower level routines are
provided as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove the disk and queue NULL checks in blkdev_issue_flush

Both of these never can be NULL for a live block device.

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

block: remove the error_sector argument to blkdev_issue_flush

The argument isn't used by any caller, and drivers don't fill out
bi_sector for flush requests either.

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

block: Remove unused flush_queue_delayed in struct blk_flush_queue

The flush_queue_delayed was introdued to hold queue if flush is
running for non-queueable flush drive by commit 3ac0cc450870
("hold queue if flush is running for non-queueable flush drive"),
but the non mq parts of the flush code had been removed by
commit 7e992f847a08 ("block: remove non mq parts from the flush code"),
as well as removing the usage of the flush_queue_delayed flag.
Thus remove the unused flush_queue_delayed flag.

Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

null_blk: Zero-initialize read buffers in non-memory-backed mode

This patch suppresses an uninteresting KMSAN complaint without affecting
performance of the null_blk driver if CONFIG_KMSAN is disabled.

Reported-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Alexander Potapenko <glider@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Document the bio_vec properties

Since it is nontrivial that nth_page() does not have to be used for a
bio_vec, document this.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
CC: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bio.h: Declare the arguments of the bio iteration functions const

This change makes it possible to pass 'const struct bio *' arguments to
these functions.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Fix type of first compat_put_{,u}long() argument

This patch fixes the following sparse warnings:

block/ioctl.c:209:16: warning: incorrect type in argument 1 (different address spaces)
block/ioctl.c:209:16:    expected void const volatile [noderef] <asn:1> *
block/ioctl.c:209:16:    got signed int [usertype] *argp
block/ioctl.c:214:16: warning: incorrect type in argument 1 (different address spaces)
block/ioctl.c:214:16:    expected void const volatile [noderef] <asn:1> *
block/ioctl.c:214:16:    got unsigned int [usertype] *argp
block/ioctl.c:666:40: warning: incorrect type in argument 1 (different address spaces)
block/ioctl.c:666:40:    expected signed int [usertype] *argp
block/ioctl.c:666:40:    got void [noderef] <asn:1> *argp
block/ioctl.c:672:41: warning: incorrect type in argument 1 (different address spaces)
block/ioctl.c:672:41:    expected unsigned int [usertype] *argp
block/ioctl.c:672:41:    got void [noderef] <asn:1> *argp

Fixes: 9b81648cb5e3 ("compat_ioctl: simplify up block/ioctl.c")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: merge part_{inc,dev}_in_flight into their only callers

part_inc_in_flight and part_dec_in_flight only have one caller each, and
those callers are purely for bio based drivers.  Merge each function into
the only caller, and remove the superflous blk-mq checks.

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

block: don't call part_{inc,dec}_in_flight for blk-mq devices

part_inc_in_flight and part_dec_in_flight are no-ops for blk-mq queues,
so remove the calls in purely blk-mq callers.

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

block: move the blk-mq calls out of part_in_flight{,_rw}

Don't bother to call part_in_flight / part_in_flight_rw on blk-mq
devices, just call the blk-mq versions directly.

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

block: mark blk_account_io_completion static

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

blk-mq: allow blk_mq_make_request to consume the q_usage_counter reference

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

blk-mq: remove a pointless queue enter pair in blk_mq_alloc_request_hctx

No need for two queue references.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: remove a pointless queue enter pair in blk_mq_alloc_request

No need for two queue references.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: move the call to blk_queue_enter_live out of blk_mq_get_request

Move the blk_queue_enter_live calls into the callers, where they can
successively be cleaned up.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blktrace: Report pid with note messages

Currently informational messages within block trace do not have PID
information of the process reporting the message included. With BFQ it
is sometimes useful to have the information and there's no good reason
to omit the information from the trace. So just fill in pid information
when generating note message.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove the REQ_NOWAIT_INLINE flag

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: blk-crypto-fallback for Inline Encryption

Blk-crypto delegates crypto operations to inline encryption hardware
when available. The separately configurable blk-crypto-fallback contains
a software fallback to the kernel crypto API - when enabled, blk-crypto
will use this fallback for en/decryption when inline encryption hardware
is not available.

This lets upper layers not have to worry about whether or not the
underlying device has support for inline encryption before deciding to
specify an encryption context for a bio. It also allows for testing
without actual inline encryption hardware - in particular, it makes it
possible to test the inline encryption code in ext4 and f2fs simply by
running xfstests with the inlinecrypt mount option, which in turn allows
for things like the regular upstream regression testing of ext4 to cover
the inline encryption code paths.

For more details, refer to Documentation/block/inline-encryption.rst.

Signed-off-by: Satya Tangirala <satyat@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Make blk-integrity preclude hardware inline encryption

Whenever a device supports blk-integrity, make the kernel pretend that
the device doesn't support inline encryption (essentially by setting the
keyslot manager in the request queue to NULL).

There's no hardware currently that supports both integrity and inline
encryption. However, it seems possible that there will be such hardware
in the near future (like the NVMe key per I/O support that might support
both inline encryption and PI).

But properly integrating both features is not trivial, and without
real hardware that implements both, it is difficult to tell if it will
be done correctly by the majority of hardware that support both.
So it seems best not to support both features together right now, and
to decide what to do at probe time.

Signed-off-by: Satya Tangirala <satyat@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Inline encryption support for blk-mq

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: Satya Tangirala <satyat@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Keyslot Manager for Inline Encryption

Inline Encryption hardware allows software to specify an encryption context
(an encryption key, crypto algorithm, data unit num, data unit size) along
with a data transfer request to a storage device, and the inline encryption
hardware will use that context to en/decrypt the data. The inline
encryption hardware is part of the storage device, and it conceptually sits
on the data path between system memory and the storage device.

Inline Encryption hardware implementations often function around the
concept of "keyslots". These implementations often have a limited number
of "keyslots", each of which can hold a key (we say that a key can be
"programmed" into a keyslot). Requests made to the storage device may have
a keyslot and a data unit number associated with them, and the inline
encryption hardware will en/decrypt the data in the requests using the key
programmed into that associated keyslot and the data unit number specified
with the request.

As keyslots are limited, and programming keys may be expensive in many
implementations, and multiple requests may use exactly the same encryption
contexts, we introduce a Keyslot Manager to efficiently manage keyslots.

We also introduce a blk_crypto_key, which will represent the key that's
programmed into keyslots managed by keyslot managers. The keyslot manager
also functions as the interface that upper layers will use to program keys
into inline encryption hardware. For more information on the Keyslot
Manager, refer to documentation found in block/keyslot-manager.c and
linux/keyslot-manager.h.

Co-developed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Documentation: Document the blk-crypto framework

The blk-crypto framework adds support for inline encryption. There are
numerous changes throughout the storage stack. This patch documents the
main design choices in the block layer, the API presented to users of
the block layer (like fscrypt or layered devices) and the API presented
to drivers for adding support for inline encryption.

Signed-off-by: Satya Tangirala <satyat@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

iocost: don't let vrate run wild while there's no saturation signal

When the QoS targets are met and nothing is being throttled, there's
no way to tell how saturated the underlying device is - it could be
almost entirely idle, at the cusp of saturation or anywhere inbetween.
Given that there's no information, it's best to keep vrate as-is in
this state.  Before 7cd806a9a953 ("iocost: improve nr_lagging
handling"), this was the case - if the device isn't missing QoS
targets and nothing is being throttled, busy_level was reset to zero.

While fixing nr_lagging handling, 7cd806a9a953 ("iocost: improve
nr_lagging handling") broke this.  Now, while the device is hitting
QoS targets and nothing is being throttled, vrate keeps getting
adjusted according to the existing busy_level.

This led to vrate keeping climing till it hits max when there's an IO
issuer with limited request concurrency if the vrate started low.
vrate starts getting adjusted upwards until the issuer can issue IOs
w/o being throttled.  From then on, QoS targets keeps getting met and
nothing on the system needs throttling and vrate keeps getting
increased due to the existing busy_level.

This patch makes the following changes to the busy_level logic.

* Reset busy_level if nr_shortages is zero to avoid the above
  scenario.

* Make non-zero nr_lagging block lowering nr_level but still clear
  positive busy_level if there's clear non-saturation signal - QoS
  targets are met and nr_shortages is non-zero.  nr_lagging's role is
  preventing adjusting vrate upwards while there are long-running
  commands and it shouldn't keep busy_level positive while there's
  clear non-saturation signal.

* Restructure code for clarity and add comments.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Andy Newell <newella@fb.com>
Fixes: 7cd806a9a953 ("iocost: improve nr_lagging handling")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move blk_io_schedule() out of header file

blk_io_schedule() isn't called from performance sensitive code path, and
it is easier to maintain by exporting it as symbol.

Also blk_io_schedule() is only called by CONFIG_BLOCK code, so it is safe
to do this way. Meantime fixes build failure when CONFIG_BLOCK is off.

Cc: Christoph Hellwig <hch@infradead.org>
Fixes: e6249cdd46e4 ("block: add blk_io_schedule() for avoiding task hung in sync dio")
Reported-by: Satya Tangirala <satyat@google.com>
Tested-by: Satya Tangirala <satyat@google.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

zonefs: use REQ_OP_ZONE_APPEND for sync DIO

Synchronous direct I/O to a sequential write only zone can be issued using
the new REQ_OP_ZONE_APPEND request operation. As dispatching multiple
BIOs can potentially result in reordering, we cannot support asynchronous
IO via this interface.

We also can only dispatch up to queue_max_zone_append_sectors() via the
new zone-append method and have to return a short write back to user-space
in case an IO larger than queue_max_zone_append_sectors() has been issued.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Acked-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: export bio_release_pages and bio_iov_iter_get_pages

Export bio_release_pages and bio_iov_iter_get_pages, so they can be used
from modular code.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

null_blk: Support REQ_OP_ZONE_APPEND

Support REQ_OP_ZONE_APPEND requests for null_blk devices with zoned
mode enabled. Use the internally tracked zone write pointer position
as the actual write position and return it using the command request
__sector field in the case of an mq device and using the command BIO
sector in the case of a BIO device.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

scsi: sd_zbc: emulate ZONE_APPEND commands

Emulate ZONE_APPEND for SCSI disks using a regular WRITE(16) command
with a start LBA set to the target zone write pointer position.

In order to always know the write pointer position of a sequential write
zone, the write pointer of all zones is tracked using an array of 32bits
zone write pointer offset attached to the scsi disk structure. Each
entry of the array indicate a zone write pointer position relative to
the zone start sector. The write pointer offsets are maintained in sync
with the device as follows:
1) the write pointer offset of a zone is reset to 0 when a
   REQ_OP_ZONE_RESET command completes.
2) the write pointer offset of a zone is set to the zone size when a
   REQ_OP_ZONE_FINISH command completes.
3) the write pointer offset of a zone is incremented by the number of
   512B sectors written when a write, write same or a zone append
   command completes.
4) the write pointer offset of all zones is reset to 0 when a
   REQ_OP_ZONE_RESET_ALL command completes.

Since the block layer does not write lock zones for zone append
commands, to ensure a sequential ordering of the regular write commands
used for the emulation, the target zone of a zone append command is
locked when the function sd_zbc_prepare_zone_append() is called from
sd_setup_read_write_cmnd(). If the zone write lock cannot be obtained
(e.g. a zone append is in-flight or a regular write has already locked
the zone), the zone append command dispatching is delayed by returning
BLK_STS_ZONE_RESOURCE.

To avoid the need for write locking all zones for REQ_OP_ZONE_RESET_ALL
requests, use a spinlock to protect accesses and modifications of the
zone write pointer offsets. This spinlock is initialized from sd_probe()
using the new function sd_zbc_init().

Co-developed-by: Damien Le Moal <Damien.LeMoal@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

scsi: sd_zbc: factor out sanity checks for zoned commands

Factor sanity checks for zoned commands from sd_zbc_setup_zone_mgmt_cmnd().

This will help with the introduction of an emulated ZONE_APPEND command.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Modify revalidate zones

Modify the interface of blk_revalidate_disk_zones() to add an optional
driver callback function that a driver can use to extend processing
done during zone revalidation. The callback, if defined, is executed
with the device request queue frozen, after all zones have been
inspected.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: introduce blk_req_zone_write_trylock

Introduce blk_req_zone_write_trylock(), which either grabs the write-lock
for a sequential zone or returns false, if the zone is already locked.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Introduce REQ_OP_ZONE_APPEND

Define REQ_OP_ZONE_APPEND to append-write sectors to a zone of a zoned
block device. This is a no-merge write operation.

A zone append write BIO must:
* Target a zoned block device
* Have a sector position indicating the start sector of the target zone
* The target zone must be a sequential write zone
* The BIO must not cross a zone boundary
* The BIO size must not be split to ensure that a single range of LBAs
  is written with a single command.

Implement these checks in generic_make_request_checks() using the
helper function blk_check_zone_append(). To avoid write append BIO
splitting, introduce the new max_zone_append_sectors queue limit
attribute and ensure that a BIO size is always lower than this limit.
Export this new limit through sysfs and check these limits in bio_full().

Also when a LLDD can't dispatch a request to a specific zone, it
will return BLK_STS_ZONE_RESOURCE indicating this request needs to
be delayed, e.g.  because the zone it will be dispatched to is still
write-locked. If this happens set the request aside in a local list
to continue trying dispatching requests such as READ requests or a
WRITE/ZONE_APPEND requests targetting other zones. This way we can
still keep a high queue depth without starving other requests even if
one request can't be served due to zone write-locking.

Finally, make sure that the bio sector position indicates the actual
write position as indicated by the device on completion.

Signed-off-by: Keith Busch <kbusch@kernel.org>
[ jth: added zone-append specific add_page and merge_page helpers ]
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: rename __bio_add_pc_page to bio_add_hw_page

Rename __bio_add_pc_page() to bio_add_hw_page() and explicitly pass in a
max_sectors argument.

This max_sectors argument can be used to specify constraints from the
hardware.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[ jth: rebased and made public for blk-map.c ]
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: provide fallbacks for blk_queue_zone_is_seq and blk_queue_zone_no

blk_queue_zone_is_seq() and blk_queue_zone_no() have not been called with
CONFIG_BLK_DEV_ZONED disabled until now.

The introduction of REQ_OP_ZONE_APPEND will change this, so we need to
provide noop fallbacks for the !CONFIG_BLK_DEV_ZONED case.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add blk_io_schedule() for avoiding task hung in sync dio

Sync dio could be big, or may take long time in discard or in case of
IO failure.

We have prevented task hung in submit_bio_wait() and blk_execute_rq(),
so apply the same trick for prevent task hung from happening in sync dio.

Add helper of blk_io_schedule() and use io_schedule_timeout() to prevent
task hung warning.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Cc: Salman Qazi <sqazi@google.com>
Cc: Jesse Barnes <jsbarnes@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: don't hold part0's refcount in IO path

gendisk can't be gone when there is IO activity, so not hold
part0's refcount in IO path.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Yufen Yu <yuyufen@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: re-organize fields of 'struct hd_part'

Put all fields accessed in IO path together at the beginning
of the struct, so that all can be fetched in single cacheline.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Yufen Yu <yuyufen@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: only define 'nr_sects_seq' in hd_part for 32bit SMP

The seqcount of 'nr_sects_seq' is only needed in case of 32bit SMP,
so define it just for 32bit SMP.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Yufen Yu <yuyufen@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: fix use-after-free on cached last_lookup partition

delete_partition() clears the cached last_lookup partition. However the
.last_lookup cache may be overwritten by one IO path after it is cleared
from delete_partition(). Then another IO path may use the cached deleting
partition after hd_struct_free() is called, then use-after-free is triggered
on the cached partition.

Fixes the issue by the following approach:

1) always get the partition's refcount via hd_struct_try_get() before
setting .last_lookup

2) move clearing .last_lookup from delete_partition() to hd_struct_free()
which is the release handle of the partition's percpu-refcount, so that no
IO path can cache deleteing partition via .last_lookup.

It is one candidate approach of Yufen's patch[1] which adds overhead
in fast path by indirect lookup which may introduce one extra cacheline
in IO path. Also this patch relies on percpu-refcount's protection, and
it is easier to understand and verify.

[1] https://lore.kernel.org/linux-block/20200109013551.GB9655@ming.t460p/T/#t

Reported-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: reset mapping if failed to update hardware queue count

When we increase hardware queue count, blk_mq_update_queue_map will
reset the mapping between cpu and hardware queue base on the hardware
queue count(set->nr_hw_queues). The mapping cannot be reset if it
encounters error in blk_mq_realloc_hw_ctxs, but the fallback flow will
continue using it, then blk_mq_map_swqueue will touch a invalid memory,
because the mapping points to a wrong hctx.

blktest block/030:

null_blk: module loaded
Increasing nr_hw_queues to 8 fails, fallback to 1
==================================================================
BUG: KASAN: null-ptr-deref in blk_mq_map_swqueue+0x2f2/0x830
Read of size 8 at addr 0000000000000128 by task nproc/8541

CPU: 5 PID: 8541 Comm: nproc Not tainted 5.7.0-rc4-dbg+ #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.13.0-0-gf21b5a4-rebuilt.opensuse.org 04/01/2014
Call Trace:
dump_stack+0xa5/0xe6
__kasan_report.cold+0x65/0xbb
kasan_report+0x45/0x60
check_memory_region+0x15e/0x1c0
__kasan_check_read+0x15/0x20
blk_mq_map_swqueue+0x2f2/0x830
__blk_mq_update_nr_hw_queues+0x3df/0x690
blk_mq_update_nr_hw_queues+0x32/0x50
nullb_device_submit_queues_store+0xde/0x160 [null_blk]
configfs_write_file+0x1c4/0x250 [configfs]
__vfs_write+0x4c/0x90
vfs_write+0x14b/0x2d0
ksys_write+0xdd/0x180
__x64_sys_write+0x47/0x50
do_syscall_64+0x6f/0x310
entry_SYSCALL_64_after_hwframe+0x49/0xb3

Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com>
Tested-by: Bart van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdi: fix up for "remove the name field in struct backing_dev_info"

Fixes: 1cd925d58385 ("bdi: remove the name field in struct backing_dev_info")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

hfs: stop using ioctl_by_bdev

Instead just call the CDROM layer functionality directly.

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

bdi: remove the name field in struct backing_dev_info

The name is only printed for a not registered bdi in writeback.  Use the
device name there as is more useful anyway for the unlike case that the
warning triggers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdi: simplify bdi_alloc

Merge the _node vs normal version and drop the superflous gfp_t argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdi: remove bdi_register_owner

Split out a new bdi_set_owner helper to set the owner, and move the policy
for creating the bdi name back into genhd.c, where it belongs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdi: unexport bdi_register_va

bdi_register_va is only used by super.c, which can't be modular.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

driver core: remove device_create_vargs

All external users of device_create_vargs are gone, so remove it and
open code it in the only caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: rename blk_mq_alloc_rq_maps

rename blk_mq_alloc_rq_maps to blk_mq_alloc_map_and_requests,
this function allocs both map and request, make function name align
with funtion.

Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: rename __blk_mq_alloc_rq_map

rename __blk_mq_alloc_rq_map to __blk_mq_alloc_map_and_request,
actually it alloc both map and request, make function name
align with function.

Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: alloc map and request for new hardware queue

Alloc new map and request for new hardware queue when increse
hardware queue count. Before this patch, it will show a
warning for each new hardware queue, but it's not enough, these
hctx have no maps and reqeust, when a bio was mapped to these
hardware queue, it will trigger kernel panic when get request
from these hctx.

Test environment:
 * A NVMe disk supports 128 io queues
 * 96 cpus in system

A corner case can always trigger this panic, there are 96
io queues allocated for HCTX_TYPE_DEFAULT type, the corresponding kernel
log: nvme nvme0: 96/0/0 default/read/poll queues. Now we set nvme write
queues to 96, then nvme will alloc others(32) queues for read, but
blk_mq_update_nr_hw_queues does not alloc map and request for these new
added io queues. So when process read nvme disk, it will trigger kernel
panic when get request from these hardware context.

Reproduce script:

nr=$(expr `cat /sys/block/nvme0n1/device/queue_count` - 1)
echo $nr > /sys/module/nvme/parameters/write_queues
echo 1 > /sys/block/nvme0n1/device/reset_controller
dd if=/dev/nvme0n1 of=/dev/null bs=4K count=1

[ 8040.805626] ------------[ cut here ]------------
[ 8040.805627] WARNING: CPU: 82 PID: 12921 at block/blk-mq.c:2578 blk_mq_map_swqueue+0x2b6/0x2c0
[ 8040.805627] Modules linked in: nvme nvme_core nf_conntrack_netlink xt_addrtype br_netfilter overlay xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT nft_counter nf_nat_tftp nf_conntrack_tftp nft_masq nf_tables_set nft_fib_inet nft_f
ib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack tun bridge nf_defrag_ipv6 nf_defrag_ipv4 stp llc ip6_tables ip_tables nft_compat rfkill ip_set nf_tables nfne
tlink sunrpc intel_rapl_msr intel_rapl_common skx_edac nfit libnvdimm x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass ipmi_ssif crct10dif_pclmul crc32_pclmul iTCO_wdt iTCO_vendor_support ghash_clmulni_intel intel_
cstate intel_uncore raid0 joydev intel_rapl_perf ipmi_si pcspkr mei_me ioatdma sg ipmi_devintf mei i2c_i801 dca lpc_ich ipmi_msghandler acpi_power_meter acpi_pad xfs libcrc32c sd_mod ast i2c_algo_bit drm_vram_helper drm_ttm_helper ttm d
rm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops
[ 8040.805637]  ahci drm i40e libahci crc32c_intel libata t10_pi wmi dm_mirror dm_region_hash dm_log dm_mod [last unloaded: nvme_core]
[ 8040.805640] CPU: 82 PID: 12921 Comm: kworker/u194:2 Kdump: loaded Tainted: G        W         5.6.0-rc5.78317c+ #2
[ 8040.805640] Hardware name: Inspur SA5212M5/YZMB-00882-104, BIOS 4.0.9 08/27/2019
[ 8040.805641] Workqueue: nvme-reset-wq nvme_reset_work [nvme]
[ 8040.805642] RIP: 0010:blk_mq_map_swqueue+0x2b6/0x2c0
[ 8040.805643] Code: 00 00 00 00 00 41 83 c5 01 44 39 6d 50 77 b8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 8b bb 98 00 00 00 89 d6 e8 8c 81 03 00 eb 83 <0f> 0b e9 52 ff ff ff 0f 1f 00 0f 1f 44 00 00 41 57 48 89 f1 41 56
[ 8040.805643] RSP: 0018:ffffba590d2e7d48 EFLAGS: 00010246
[ 8040.805643] RAX: 0000000000000000 RBX: ffff9f013e1ba800 RCX: 000000000000003d
[ 8040.805644] RDX: ffff9f00ffff6000 RSI: 0000000000000003 RDI: ffff9ed200246d90
[ 8040.805644] RBP: ffff9f00f6a79860 R08: 0000000000000000 R09: 000000000000003d
[ 8040.805645] R10: 0000000000000001 R11: ffff9f0138c3d000 R12: ffff9f00fb3a9008
[ 8040.805645] R13: 000000000000007f R14: ffffffff96822660 R15: 000000000000005f
[ 8040.805645] FS:  0000000000000000(0000) GS:ffff9f013fa80000(0000) knlGS:0000000000000000
[ 8040.805646] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 8040.805646] CR2: 00007f7f397fa6f8 CR3: 0000003d8240a002 CR4: 00000000007606e0
[ 8040.805647] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 8040.805647] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 8040.805647] PKRU: 55555554
[ 8040.805647] Call Trace:
[ 8040.805649]  blk_mq_update_nr_hw_queues+0x31b/0x390
[ 8040.805650]  nvme_reset_work+0xb4b/0xeab [nvme]
[ 8040.805651]  process_one_work+0x1a7/0x370
[ 8040.805652]  worker_thread+0x1c9/0x380
[ 8040.805653]  ? max_active_store+0x80/0x80
[ 8040.805655]  kthread+0x112/0x130
[ 8040.805656]  ? __kthread_parkme+0x70/0x70
[ 8040.805657]  ret_from_fork+0x35/0x40
[ 8040.805658] ---[ end trace b5f13b1e73ccb5d3 ]---
[ 8229.365135] BUG: kernel NULL pointer dereference, address: 0000000000000004
[ 8229.365165] #PF: supervisor read access in kernel mode
[ 8229.365178] #PF: error_code(0x0000) - not-present page
[ 8229.365191] PGD 0 P4D 0
[ 8229.365201] Oops: 0000 [#1] SMP PTI
[ 8229.365212] CPU: 77 PID: 13024 Comm: dd Kdump: loaded Tainted: G        W         5.6.0-rc5.78317c+ #2
[ 8229.365232] Hardware name: Inspur SA5212M5/YZMB-00882-104, BIOS 4.0.9 08/27/2019
[ 8229.365253] RIP: 0010:blk_mq_get_tag+0x227/0x250
[ 8229.365265] Code: 44 24 04 44 01 e0 48 8b 74 24 38 65 48 33 34 25 28 00 00 00 75 33 48 83 c4 40 5b 5d 41 5c 41 5d 41 5e c3 48 8d 68 10 4c 89 ef <44> 8b 60 04 48 89 ee e8 dd f9 ff ff 83 f8 ff 75 c8 e9 67 fe ff ff
[ 8229.365304] RSP: 0018:ffffba590e977970 EFLAGS: 00010246
[ 8229.365317] RAX: 0000000000000000 RBX: ffff9f00f6a79860 RCX: ffffba590e977998
[ 8229.365333] RDX: 0000000000000000 RSI: ffff9f012039b140 RDI: ffffba590e977a38
[ 8229.365349] RBP: 0000000000000010 R08: ffffda58ff94e190 R09: ffffda58ff94e198
[ 8229.365365] R10: 0000000000000011 R11: ffff9f00f6a79860 R12: 0000000000000000
[ 8229.365381] R13: ffffba590e977a38 R14: ffff9f012039b140 R15: 0000000000000001
[ 8229.365397] FS:  00007f481c230580(0000) GS:ffff9f013f940000(0000) knlGS:0000000000000000
[ 8229.365415] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 8229.365428] CR2: 0000000000000004 CR3: 0000005f35e26004 CR4: 00000000007606e0
[ 8229.365444] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 8229.365460] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 8229.365476] PKRU: 55555554
[ 8229.365484] Call Trace:
[ 8229.365498]  ? finish_wait+0x80/0x80
[ 8229.365512]  blk_mq_get_request+0xcb/0x3f0
[ 8229.365525]  blk_mq_make_request+0x143/0x5d0
[ 8229.365538]  generic_make_request+0xcf/0x310
[ 8229.365553]  ? scan_shadow_nodes+0x30/0x30
[ 8229.365564]  submit_bio+0x3c/0x150
[ 8229.365576]  mpage_readpages+0x163/0x1a0
[ 8229.365588]  ? blkdev_direct_IO+0x490/0x490
[ 8229.365601]  read_pages+0x6b/0x190
[ 8229.365612]  __do_page_cache_readahead+0x1c1/0x1e0
[ 8229.365626]  ondemand_readahead+0x182/0x2f0
[ 8229.365639]  generic_file_buffered_read+0x590/0xab0
[ 8229.365655]  new_sync_read+0x12a/0x1c0
[ 8229.365666]  vfs_read+0x8a/0x140
[ 8229.365676]  ksys_read+0x59/0xd0
[ 8229.365688]  do_syscall_64+0x55/0x1d0
[ 8229.365700]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com>
Tested-by: Weiping Zhang <zhangweiping@didiglobal.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: save previous hardware queue count before udpate

blk_mq_realloc_tag_set_tags will update set->nr_hw_queues, so
save old set->nr_hw_queues before call this function.

Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: free both rq_map and request

Allocation:

__blk_mq_alloc_rq_map
blk_mq_alloc_rq_map
blk_mq_alloc_rq_map
tags = blk_mq_init_tags : kzalloc_node:
tags->rqs = kcalloc_node
tags->static_rqs = kcalloc_node
blk_mq_alloc_rqs
p = alloc_pages_node
tags->static_rqs[i] = p + offset;

Free:

blk_mq_free_rq_map
kfree(tags->rqs);
kfree(tags->static_rqs);
blk_mq_free_tags
kfree(tags);

The page allocated in blk_mq_alloc_rqs cannot be released,
so we should use blk_mq_free_map_and_requests here.

blk_mq_free_map_and_requests
blk_mq_free_rqs
__free_pages : cleanup for blk_mq_alloc_rqs
blk_mq_free_rq_map : cleanup for blk_mq_alloc_rq_map

Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Merge branch 'block-5.7' into for-5.8/block

Pull in block-5.7 fixes for 5.8. Mostly to resolve a conflict with
the blk-iocost changes, but we also need the base of the bdi
use-after-free as well as we build on top of it.

* block-5.7:
  nvme: fix possible hang when ns scanning fails during error recovery
  nvme-pci: fix "slimmer CQ head update"
  bdi: add a ->dev_name field to struct backing_dev_info
  bdi: use bdi_dev_name() to get device name
  bdi: move bdi_dev_name out of line
  vboxsf: don't use the source name in the bdi name
  iocost: protect iocg->abs_vdebt with iocg->waitq.lock
  block: remove the bd_openers checks in blk_drop_partitions
  nvme: prevent double free in nvme_alloc_ns() error handling
  null_blk: Cleanup zoned device initialization
  null_blk: Fix zoned command handling
  block: remove unused header
  blk-iocost: Fix error on iocost_ioc_vrate_adj
  bdev: Reduce time holding bd_mutex in sync in blkdev_close()
  buffer: remove useless comment and WB_REASON_FREE_MORE_MEM, reason.

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

nvme: fix possible hang when ns scanning fails during error recovery

When the controller is reconnecting, the host fails I/O and admin
commands as the host cannot reach the controller. ns scanning may
revalidate namespaces during that period and it is wrong to remove
namespaces due to these failures as we may hang (see 205da2434301).

One command that may fail is nvme_identify_ns_descs. Since we return
success due to having ns identify descriptor list optional, we continue
to compare ns identifiers in nvme_revalidate_disk, obviously fail and
return -ENODEV to nvme_validate_ns, which will remove the namespace.

Exactly what we don't want to happen.

Fixes: 22802bf742c2 ("nvme: Namepace identification descriptor list is optional")
Tested-by: Anton Eidelman <anton@lightbitslabs.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme-pci: fix "slimmer CQ head update"

Pre-incrementing ->cq_head can't be done in memory because OOB value
can be observed by another context.

This devalues space savings compared to original code :-\

$ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux
add/remove: 0/0 grow/shrink: 0/4 up/down: 0/-32 (-32)
Function                                     old     new   delta
nvme_poll_irqdisable                         464     456      -8
nvme_poll                                    455     447      -8
nvme_irq                                     388     380      -8
nvme_dev_disable                             955     947      -8

But the code is minimal now: one read for head, one read for q_depth,
one increment, one comparison, single instruction phase bit update and
one write for new head.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: John Garry <john.garry@huawei.com>
Tested-by: John Garry <john.garry@huawei.com>
Fixes: e2a366a4b0feaeb ("nvme-pci: slimmer CQ head update")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdi: add a ->dev_name field to struct backing_dev_info

Cache a copy of the name for the life time of the backing_dev_info
structure so that we can reference it even after unregistering.

Fixes: 68f23b89067f ("memcg: fix a crash in wb_workfn when a device disappears")
Reported-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdi: use bdi_dev_name() to get device name

Use the common interface bdi_dev_name() to get device name.

Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Add missing <linux/backing-dev.h> include BFQ

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

bdi: move bdi_dev_name out of line

bdi_dev_name is not a fast path function, move it out of line.  This
prepares for using it from modular callers without having to export
an implementation detail like bdi_unknown_name.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

vboxsf: don't use the source name in the bdi name

Simplify the bdi name to mirror what we are doing elsewhere, and
drop them name in favor of just using a number.  This avoids a
potentially very long bdi name.

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

iocost: protect iocg->abs_vdebt with iocg->waitq.lock

abs_vdebt is an atomic_64 which tracks how much over budget a given cgroup
is and controls the activation of use_delay mechanism. Once a cgroup goes
over budget from forced IOs, it has to pay it back with its future budget.
The progress guarantee on debt paying comes from the iocg being active -
active iocgs are processed by the periodic timer, which ensures that as time
passes the debts dissipate and the iocg returns to normal operation.

However, both iocg activation and vdebt handling are asynchronous and a
sequence like the following may happen.

1. The iocg is in the process of being deactivated by the periodic timer.

2. A bio enters ioc_rqos_throttle(), calls iocg_activate() which returns
   without anything because it still sees that the iocg is already active.

3. The iocg is deactivated.

4. The bio from #2 is over budget but needs to be forced. It increases
   abs_vdebt and goes over the threshold and enables use_delay.

5. IO control is enabled for the iocg's subtree and now IOs are attributed
   to the descendant cgroups and the iocg itself no longer issues IOs.

This leaves the iocg with stuck abs_vdebt - it has debt but inactive and no
further IOs which can activate it. This can end up unduly punishing all the
descendants cgroups.

The usual throttling path has the same issue - the iocg must be active while
throttled to ensure that future event will wake it up - and solves the
problem by synchronizing the throttling path with a spinlock. abs_vdebt
handling is another form of overage handling and shares a lot of
characteristics including the fact that it isn't in the hottest path.

This patch fixes the above and other possible races by strictly
synchronizing abs_vdebt and use_delay handling with iocg->waitq.lock.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Vlad Dmitriev <vvd@fb.com>
Cc: stable@vger.kernel.org # v5.4+
Fixes: e1518f63f246 ("blk-iocost: Don't let merges push vtime into the future")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

udf: stop using ioctl_by_bdev

Instead just call the CDROM layer functionality directly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

isofs: stop using ioctl_by_bdev

Instead just call the CDROM layer functionality directly, and turn the
hot mess in isofs_get_last_session into remotely readable code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

hfsplus: stop using ioctl_by_bdev

Instead just call the CDROM layer functionality directly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

cdrom: factor out a cdrom_multisession helper

Factor out a version of the CDROMMULTISESSION ioctl handler that can
be called directly from kernel space.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

cdrom: factor out a cdrom_read_tocentry helper

Factor out a version of the CDROMREADTOCENTRY ioctl handler that can
be called directly from kernel space.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

ide-cd: rename cdrom_read_tocentry

Give the cdrom_read_tocentry function and ide_ prefix to not conflict
with the soon to be added generic function.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add a cdrom_device_info pointer to struct gendisk

Add a pointer to the CDROM information structure to struct gendisk.
This will allow various removable media file systems to call directly
into the CDROM layer instead of abusing ioctls with kernel pointers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

iocost_monitor: drop string wrap around numbers when outputting json

Wrapping numbers in strings is used by some to work around bit-width issues in
some enviroments. The problem isn't innate to json and the workaround seems to
cause more integration problems than help. Let's drop the string wrapping.

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

iocost_monitor: exit successfully if interval is zero

This is to help external tools to decide whether iocost_monitor has all its
requirements met or not based on the exit status of an -i0 run.

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

blk-iocost: account for IO size when testing latencies

On each IO completion, iocost decides whether the IO met or missed its latency
target. Currently, the targets are fixed numbers per IO type. While this can be
good enough for loose latency targets way higher than typical completion
latencies, the effect of IO size makes it difficult to tighten the latency
target - a target adequate for 4k IOs might be too tight for 512k IOs and
vice-versa.

iocost already has all the necessary information to account for different IO
sizes when testing whether the latency target is met as iocost can calculate the
size vtime cost of a given IO. This patch updates the completion path to
calculate the size vtime cost of the IO, deduct the nsec equivalent from the
observed latency and use the adjusted value to decide whether the target is met.

This makes latency targets independent from IO size and enables determining
adequate latency targets with fixed size fio runs.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andy Newell <newella@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>