Refactor the request alloction so that blk_mq_get_cached_request tries
to find a cached request first, and the entirely separate and now
self contained blk_mq_get_new_requests allocates one or more requests
if that is not possible.

There is a small change in behavior as submit_bio_checks is called
twice now if a cached request is present but can't be used, but that
is a small price to pay for unwinding this code.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211124062856.1444266-1-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>

Remove a repeated "#include<linux/sched/sysctl.h>".
Signed-off-by: NGuo Zhengkui <guozhengkui@vivo.com>
Reviewed-by: NChaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20211123063340.25882-1-guozhengkui@vivo.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

The only user of the io_context for IO is BFQ, yet we put the checking
and logic of it into the normal IO path.

Put the creation into blk_mq_sched_assign_ioc(), and have BFQ use that
helper.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This is essentially never used, yet it's about 1/3rd of the total
queue size. Allocate it when needed, and don't embed it in the queue.

Kill the queue flag for this while at it, since we can just check the
assigned pointer now.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We don't need to write to the bio if:

1) No ioprio value has ever been assigned to the blkcg
2) We wouldn't anyway, depending on bio and blkcg IO priority
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Keep all the functionality for adding a request to a plug in a single place.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123160443.1315598-3-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>

Set up GENHD_FL_REMOVABLE together with the rest of the gendisk fields.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-15-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Switch to an enum and tidy up the documentation.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-14-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Hidden gendisks can't be opened using blkdev_get_*, so we can't really
reach any of the partition scanning paths or partitioning ioctls except
for the initial partition scan from add_disk.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-13-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

All modern drivers can support extra partitions using the extended
dev_t.  In fact except for the ioctl method drivers never even see
partitions in normal operation.

So remove the GENHD_FL_EXT_DEVT and allow extra partitions for all
block devices that do support partitions, and require those that
do not support partitions to explicit disallow them using
GENHD_FL_NO_PART.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-12-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

This flag is not set directly anywhere and only inherited from
GENHD_FL_HIDDEN.  Just check for GENHD_FL_HIDDEN instead.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-11-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

This manually reverts 07b652cdbec3 ("mmc: card: Don't show eMMC RPMB and
BOOT areas in /proc/partitions").  Based on the commit description that
change was purely cosmetic.  mmc is the last driver that sets this
flag and thus prevents it from being removed.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NUlf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20211122130625.1136848-10-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

This manually reverts commit 27290b469051 ("null_blk: suppress invalid
partition info").  The message in that commit log can't appearch as
the flag is never checked during probing, and there is no good reason
to treat null_blk special in /proc/partitions.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-9-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Hidden gendisks never hash the block device inode, so this can't happen.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-8-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

The GENHD_FL_NO_PART_SCAN controls more than just partitions canning,
so rename it to GENHD_FL_NO_PART.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NUlf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20211122130625.1136848-7-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>

disk_max_parts never returns 0 given that ->minors for devices not using
the extended dev_t must be non-zero, and disk_max_parts always returns
DISK_MAX_PARTS for the latter.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-5-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

GENHD_FL_CD marks a gendisk as a vaguely CD-ROM like device.
Besides being used internally inside of sunvdc.c an xen-blkfront it
is used by xen-blkback as a hint to claim a device exported to a
guest is a CD-ROM like device.  Just check for disk->cdi instead
which is the right indicator for "real" CD-ROM or DVD drivers.  This
will miss the paravirtualized guest drivers, but those make little
sense to report anyway.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-4-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE is all about the event reporting
mechanism, so move it to the event_flags field.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-3-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

The flag to indicate an unlocked native capacity is dynamic state,
not a driver capability flag, so move it to disk->state.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-2-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

All request based code is in the blk-mq files now.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-12-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>

blk_dump_rq_flags deals with a request, so move it to blk-mq.c.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-10-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/20211117061404.331732-8-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

blk_rq_init deals with a request structure, so move it to blk-mq.c
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-7-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>

Move blk_mq_flush_plug_list and blk_mq_plug_issue_direct down in blk-mq.c
to prepare for marking blk_mq_request_issue_directly static without the
need of a forward declaration.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-5-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

All this code is tightly coupled to the blk-mq core, so move it
there.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-4-hch@lst.de
[axboe: remove doc generation for blk-exec.c]
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This function is trivial, and flush_dcache_page is always defined, so
just open code it in the 2.5 callers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-3-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

blk_rq_err_bytes is only used by the scsi midlayer, so move it there.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20211117061404.331732-2-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>