Now we only verify the outmost freeze & unfreeze in current context in case
that !q->mq_freeze_depth, so it is reliable to save queue lying state when
we want to lock the freeze queue since the state is one per-task variable
now.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241127135133.3952153-5-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Make bio_is_zone_append globally available, because file systems need
to use to check for a zone append bio in their end_io handlers to deal
with the block layer emulation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20241104062647.91160-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
commit f1be1788a3 ("block: model freeze & enter queue as lock for
supporting lockdep") tries to apply lockdep for verifying freeze &
unfreeze. However, the verification is only done the outmost freeze and
unfreeze. This way is actually not correct because q->mq_freeze_depth
still may drop to zero on other task instead of the freeze owner task.
Fix this issue by always verifying the last unfreeze lock on the owner
task context, and make sure both the outmost freeze & unfreeze are
verified in the current task.
Fixes: f1be1788a3 ("block: model freeze & enter queue as lock for supporting lockdep")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241031133723.303835-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No one use blk_freeze_queue(), so remove it and the obsolete comment.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241031133723.303835-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Recently we got several deadlock report[1][2][3] caused by
blk_mq_freeze_queue and blk_enter_queue().
Turns out the two are just like acquiring read/write lock, so model them
as read/write lock for supporting lockdep:
1) model q->q_usage_counter as two locks(io and queue lock)
- queue lock covers sync with blk_enter_queue()
- io lock covers sync with bio_enter_queue()
2) make the lockdep class/key as per-queue:
- different subsystem has very different lock use pattern, shared lock
class causes false positive easily
- freeze_queue degrades to no lock in case that disk state becomes DEAD
because bio_enter_queue() won't be blocked any more
- freeze_queue degrades to no lock in case that request queue becomes dying
because blk_enter_queue() won't be blocked any more
3) model blk_mq_freeze_queue() as acquire_exclusive & try_lock
- it is exclusive lock, so dependency with blk_enter_queue() is covered
- it is trylock because blk_mq_freeze_queue() are allowed to run
concurrently
4) model blk_enter_queue() & bio_enter_queue() as acquire_read()
- nested blk_enter_queue() are allowed
- dependency with blk_mq_freeze_queue() is covered
- blk_queue_exit() is often called from other contexts(such as irq), and
it can't be annotated as lock_release(), so simply do it in
blk_enter_queue(), this way still covered cases as many as possible
With lockdep support, such kind of reports may be reported asap and
needn't wait until the real deadlock is triggered.
For example, lockdep report can be triggered in the report[3] with this
patch applied.
[1] occasional block layer hang when setting 'echo noop > /sys/block/sda/queue/scheduler'
https://bugzilla.kernel.org/show_bug.cgi?id=219166
[2] del_gendisk() vs blk_queue_enter() race condition
https://lore.kernel.org/linux-block/20241003085610.GK11458@google.com/
[3] queue_freeze & queue_enter deadlock in scsi
https://lore.kernel.org/linux-block/ZxG38G9BuFdBpBHZ@fedora/T/#u
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241025003722.3630252-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add support for defining read-only partitions and complete support for
it in the cmdline partition parser as the additional "ro" after a
partition is scanned but never actually applied.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241002221306.4403-2-ansuelsmth@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's now just checking whether or not RQF_IO_STAT is set, so let's get
rid of it and just open-code the specific flag that is being checked.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rather than have blk_do_io_stat() check for both RQF_IO_STAT and whether
the request is a passthrough requests every time, move both of those
checks into blk_account_io_start(). Then blk_do_io_stat() can be reduced
to just checking for RQF_IO_STAT.
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring allows implementing custom file specific asynchronous
operations via the fops->uring_cmd callback, a.k.a. IORING_OP_URING_CMD
requests or just io_uring commands. Use it to add support for async
discards.
Normally, it first tries to queue up bios in a non-blocking context,
and if that fails, we'd retry from a blocking context by returning
-EAGAIN to the core io_uring. We always get the result from bios
asynchronously by setting a custom bi_end_io callback, at which point
we drag the request into the task context to either reissue or complete
it and post a completion to the user.
Unlike ioctl(BLKDISCARD) with stronger guarantees against races, we only
do a best effort attempt to invalidate page cache, and it can race with
any writes and reads and leave page cache stale. It's the same kind of
races we allow to direct writes.
Also, apart from cases where discarding is not allowed at all, e.g.
discards are not supported or the file/device is read only, the user
should assume that the sector range on disk is not valid anymore, even
when an error was returned to the user.
Suggested-by: Conrad Meyer <conradmeyer@meta.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2b5210443e4fa0257934f73dfafcc18a77cd0e09.1726072086.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Added new bio_add_hw_folio() function as a wrapper around
bio_add_hw_page(). This is a prep patch.
Signed-off-by: Kundan Kumar <kundan.kumar@samsung.com>
Tested-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20240911064935.5630-2-kundan.kumar@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bio_split_rw is designed to split read and write bios with a payload.
Currently it is called by __bio_split_to_limits for all operations not
explicitly list, which works because bio_may_need_split explicitly checks
for bi_vcnt == 1 and thus skips the bypass if there is no payload and
bio_for_each_bvec loop will never execute it's body if bi_size is 0.
But all this is hard to understand, fragile and wasted pointless cycles.
Switch __bio_split_to_limits to only call bio_split_rw for READ and
WRITE command and don't attempt any kind split for operation that do not
require splitting.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Link: https://lore.kernel.org/r/20240826173820.1690925-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently REQ_OP_ZONE_APPEND is handled by the bio_split_rw case in
__bio_split_to_limits. This is harmful because REQ_OP_ZONE_APPEND
bios do not adhere to the soft max_limits value but instead use their
own capped version of max_hw_sectors, leading to incorrect splits that
later blow up in bio_split.
We still need the bio_split_rw logic to count nr_segs for blk-mq code,
so add a new wrapper that passes in the right limit, and turns any bio
that would need a split into an error as an additional debugging aid.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Link: https://lore.kernel.org/r/20240826173820.1690925-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The current setup with bio_may_exceed_limit and __bio_split_to_limits
is a bit of a mess.
Change it so that __bio_split_to_limits does all the work and is just
a variant of bio_split_to_limits that returns nr_segs. This is done
by inlining it and instead have the various bio_split_* helpers directly
submit the potentially split bios.
To support btrfs, the rw version has a lower level helper split out
that just returns the offset to split. This turns out to nicely clean
up the btrfs flow as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Link: https://lore.kernel.org/r/20240826173820.1690925-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-6.11/block-post-20240722' of git://git.kernel.dk/linux
Pull block integrity mapping updates from Jens Axboe:
"A set of cleanups and fixes for the block integrity support.
Sent separately from the main block changes from last week, as they
depended on later fixes in the 6.10-rc cycle"
* tag 'for-6.11/block-post-20240722' of git://git.kernel.dk/linux:
block: don't free the integrity payload in bio_integrity_unmap_free_user
block: don't free submitter owned integrity payload on I/O completion
block: call bio_integrity_unmap_free_user from blk_rq_unmap_user
block: don't call bio_uninit from bio_endio
block: also return bio_integrity_payload * from stubs
block: split integrity support out of bio.h
Get callers out of poking into bvec internals a bit more. Not a huge win
right now, but with the proposed new DMA mapping API we might end up with
a lot more of this otherwise.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240706075228.2350978-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently __bio_integrity_endio frees the integrity payload unless it is
explicitly marked as user-mapped. This means in-kernel callers that
allocate their own integrity payload never get to see it on I/O
completion. The current two users don't need it as they just pre-mapped
PI tuples received over the network, but this limits uses of integrity
data lot.
Change bio_integrity_endio to call __bio_integrity_endio for block layer
generated integrity data only, and leave freeing of submitter
allocated integrity data to bio_uninit which also gets called from
the final bio_put. This requires that unmapping user mapped or copied
integrity data is now always done by the caller, and the special
BIP_INTEGRITY_USER flag can go away.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240702151047.1746127-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Split struct bio_integrity_payload and the related prototypes out of
bio.h into a separate bio-integrity.h header so that it is only pulled
in by the few places that need it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240702151047.1746127-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the bvec interation into the generate/verify helpers to avoid a bit
of argument passing churn.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240626045950.189758-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Mark blk_apply_bdi_limits non-static and open code disk_update_readahead
in the only caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240626142637.300624-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add atomic write support, as follows:
- add helper functions to get request_queue atomic write limits
- report request_queue atomic write support limits to sysfs and update Doc
- support to safely merge atomic writes
- deal with splitting atomic writes
- misc helper functions
- add a per-request atomic write flag
New request_queue limits are added, as follows:
- atomic_write_hw_max is set by the block driver and is the maximum length
of an atomic write which the device may support. It is not
necessarily a power-of-2.
- atomic_write_max_sectors is derived from atomic_write_hw_max_sectors and
max_hw_sectors. It is always a power-of-2. Atomic writes may be merged,
and atomic_write_max_sectors would be the limit on a merged atomic write
request size. This value is not capped at max_sectors, as the value in
max_sectors can be controlled from userspace, and it would only cause
trouble if userspace could limit atomic_write_unit_max_bytes and the
other atomic write limits.
- atomic_write_hw_unit_{min,max} are set by the block driver and are the
min/max length of an atomic write unit which the device may support. They
both must be a power-of-2. Typically atomic_write_hw_unit_max will hold
the same value as atomic_write_hw_max.
- atomic_write_unit_{min,max} are derived from
atomic_write_hw_unit_{min,max}, max_hw_sectors, and block core limits.
Both min and max values must be a power-of-2.
- atomic_write_hw_boundary is set by the block driver. If non-zero, it
indicates an LBA space boundary at which an atomic write straddles no
longer is atomically executed by the disk. The value must be a
power-of-2. Note that it would be acceptable to enforce a rule that
atomic_write_hw_boundary_sectors is a multiple of
atomic_write_hw_unit_max, but the resultant code would be more
complicated.
All atomic writes limits are by default set 0 to indicate no atomic write
support. Even though it is assumed by Linux that a logical block can always
be atomically written, we ignore this as it is not of particular interest.
Stacked devices are just not supported either for now.
An atomic write must always be submitted to the block driver as part of a
single request. As such, only a single BIO must be submitted to the block
layer for an atomic write. When a single atomic write BIO is submitted, it
cannot be split. As such, atomic_write_unit_{max, min}_bytes are limited
by the maximum guaranteed BIO size which will not be required to be split.
This max size is calculated by request_queue max segments and the number
of bvecs a BIO can fit, BIO_MAX_VECS. Currently we rely on userspace
issuing a write with iovcnt=1 for pwritev2() - as such, we can rely on each
segment containing PAGE_SIZE of data, apart from the first+last, which each
can fit logical block size of data. The first+last will be LBS
length/aligned as we rely on direct IO alignment rules also.
New sysfs files are added to report the following atomic write limits:
- atomic_write_unit_max_bytes - same as atomic_write_unit_max_sectors in
bytes
- atomic_write_unit_min_bytes - same as atomic_write_unit_min_sectors in
bytes
- atomic_write_boundary_bytes - same as atomic_write_hw_boundary_sectors in
bytes
- atomic_write_max_bytes - same as atomic_write_max_sectors in bytes
Atomic writes may only be merged with other atomic writes and only under
the following conditions:
- total resultant request length <= atomic_write_max_bytes
- the merged write does not straddle a boundary
Helper function bdev_can_atomic_write() is added to indicate whether
atomic writes may be issued to a bdev. If a bdev is a partition, the
partition start must be aligned with both atomic_write_unit_min_sectors
and atomic_write_hw_boundary_sectors.
FSes will rely on the block layer to validate that an atomic write BIO
submitted will be of valid size, so add blk_validate_atomic_write_op_size()
for this purpose. Userspace expects an atomic write which is of invalid
size to be rejected with -EINVAL, so add BLK_STS_INVAL for this. Also use
BLK_STS_INVAL for when a BIO needs to be split, as this should mean an
invalid size BIO.
Flag REQ_ATOMIC is used for indicating an atomic write.
Co-developed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-6-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently blk_queue_get_max_sectors() is passed a enum req_op. In future
the value returned from blk_queue_get_max_sectors() may depend on certain
request flags, so pass a request pointer.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-2-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the bounce flag into the features field to reclaim a little bit of
space.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240617060532.127975-27-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Block layer integrity configuration is a bit complex right now, as it
indirects through operation vectors for a simple two-dimensional
configuration:
a) the checksum type of none, ip checksum, crc, crc64
b) the presence or absence of a reference tag
Remove the integrity profile, and instead add a separate csum_type flag
which replaces the existing ip-checksum field and a new flag that
indicates the presence of the reference tag.
This removes up to two layers of indirect calls, remove the need to
offload the no-op verification of non-PI metadata to a workqueue and
generally simplifies the code. The downside is that block/t10-pi.c now
has to be built into the kernel when CONFIG_BLK_DEV_INTEGRITY is
supported. Given that both nvme and SCSI require t10-pi.ko, it is loaded
for all usual configurations that enabled CONFIG_BLK_DEV_INTEGRITY
already, though.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240613084839.1044015-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Replacement of bdev->bd_inode with sane(r) set of primitives.
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Merge tag 'pull-bd_inode-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull bdev bd_inode updates from Al Viro:
"Replacement of bdev->bd_inode with sane(r) set of primitives by me and
Yu Kuai"
* tag 'pull-bd_inode-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
RIP ->bd_inode
dasd_format(): killing the last remaining user of ->bd_inode
nilfs_attach_log_writer(): use ->bd_mapping->host instead of ->bd_inode
block/bdev.c: use the knowledge of inode/bdev coallocation
gfs2: more obvious initializations of mapping->host
fs/buffer.c: massage the remaining users of ->bd_inode to ->bd_mapping
blk_ioctl_{discard,zeroout}(): we only want ->bd_inode->i_mapping here...
grow_dev_folio(): we only want ->bd_inode->i_mapping there
use ->bd_mapping instead of ->bd_inode->i_mapping
block_device: add a pointer to struct address_space (page cache of bdev)
missing helpers: bdev_unhash(), bdev_drop()
block: move two helpers into bdev.c
block2mtd: prevent direct access of bd_inode
dm-vdo: use bdev_nr_bytes(bdev) instead of i_size_read(bdev->bd_inode)
blkdev_write_iter(): saner way to get inode and bdev
bcachefs: remove dead function bdev_sectors()
ext4: remove block_device_ejected()
erofs_buf: store address_space instead of inode
erofs: switch erofs_bread() to passing offset instead of block number
One the one hand, it's marked EXPERIMENTAL since 2017, and looks like
there are no users since then, and no testers and no developers, it's
just not active at all.
On the other hand, even if the config is disabled, there are still many
fields in throtl_grp and throtl_data and many functions that are only
used for throtl low.
At last, currently blk-throtl is initialized during disk initialization,
and destroyed during disk removal, and it exposes many functions to be
called directly from block layer.
Remove throtl low to make code much more cleaner and follow up work much
easier.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240509121107.3195568-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, io_ticks is accounted based on sampling, specifically
update_io_ticks() will always account io_ticks by 1 jiffies from
bdev_start_io_acct()/blk_account_io_start(), and the result can be
inaccurate, for example(HZ is 250):
Test script:
fio -filename=/dev/sda -bs=4k -rw=write -direct=1 -name=test -thinktime=4ms
Test result: util is about 90%, while the disk is really idle.
This behaviour is introduced by commit 5b18b5a737 ("block: delete
part_round_stats and switch to less precise counting"), however, there
was a key point that is missed that this patch also improve performance
a lot:
Before the commit:
part_round_stats:
if (part->stamp != now)
stats |= 1;
part_in_flight()
-> there can be lots of task here in 1 jiffies.
part_round_stats_single()
__part_stat_add()
part->stamp = now;
After the commit:
update_io_ticks:
stamp = part->bd_stamp;
if (time_after(now, stamp))
if (try_cmpxchg())
__part_stat_add()
-> only one task can reach here in 1 jiffies.
Hence in order to account io_ticks precisely, we only need to know if
there are IO inflight at most once in one jiffies. Noted that for
rq-based device, iterating tags should not be used here because
'tags->lock' is grabbed in blk_mq_find_and_get_req(), hence
part_stat_lock_inc/dec() and part_in_flight() is used to trace inflight.
The additional overhead is quite little:
- per cpu add/dec for each IO for rq-based device;
- per cpu sum for each jiffies;
And it's verified by null-blk that there are no performance degration
under heavy IO pressure.
Fixes: 5b18b5a737 ("block: delete part_round_stats and switch to less precise counting")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240509123717.3223892-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a helper to wait for an entire chain of bios to complete.
[hch: split from a larger patch, moved and changed the name now that it
is non-static]
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240506042027.2289826-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bdev_unhash(): make block device invisible to lookups by device number
bdev_drop(): drop reference to associated inode.
Both are internal, for use by genhd and partition-related code - similar
to bdev_add(). The logics in there (especially the lifetime-related
parts of it) ought to be cleaned up, but that's a separate story; here
we just encapsulate getting to associated inode.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
blk_zone_complete_request() must be called to handle the completion of a
zone write request handled with zone write plugging. This function is
called from blk_complete_request(), blk_update_request() and also in
blk_mq_submit_bio() error path. Improve this by moving this function
call into blk_mq_finish_request() as all requests are processed with
this function when they complete as well as when they are freed without
being executed. This also improves blk_update_request() used by scsi
devices as these may repeatedly call this function to handle partial
completions.
To be consistent with this change, blk_zone_complete_request() is
renamed to blk_zone_finish_request() and
blk_zone_write_plug_complete_request() is renamed to
blk_zone_write_plug_finish_request().
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240501110907.96950-12-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Zone write plugging ignores empty (no data) flush operations but handles
flush BIOs that have data to ensure that the flush machinery generated
write is processed in order. However, the call to
blk_zone_write_plug_attempt_merge() which sets a request
RQF_ZONE_WRITE_PLUGGING flag is called after blk_insert_flush(), thus
missing indicating that a non empty flush request completion needs
handling by zone write plugging.
Fix this by moving the call to blk_zone_write_plug_attempt_merge()
before blk_insert_flush(). And while at it, rename that function as
blk_zone_write_plug_init_request() to be clear that it is not just about
merging plugged BIOs in the request. While at it, also add a WARN_ONCE()
check that the zone write plug for the request is not NULL.
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240501110907.96950-10-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Given that zone write plugging manages all writes to zones of a zoned
block device and tracks the write pointer position of all zones that are
not full nor empty, emulating zone append operations using regular
writes can be implemented generically, without relying on the underlying
device driver to implement such emulation. This is needed for devices
that do not natively support the zone append command (e.g. SMR
hard-disks).
A device may request zone append emulation by setting its
max_zone_append_sectors queue limit to 0. For such device, the function
blk_zone_wplug_prepare_bio() changes zone append BIOs into
non-mergeable regular write BIOs. Modified zone append BIOs are flagged
with the new BIO flag BIO_EMULATES_ZONE_APPEND. This flag is checked
on completion of the BIO in blk_zone_write_plug_bio_endio() to restore
the original REQ_OP_ZONE_APPEND operation code of the BIO.
The block layer internal inline helper function bio_is_zone_append() is
added to test if a BIO is either a native zone append operation
(REQ_OP_ZONE_APPEND operation code) or if it is flagged with
BIO_EMULATES_ZONE_APPEND. Given that both native and emulated zone
append BIO completion handling should be similar, The functions
blk_update_request() and blk_zone_complete_request_bio() are modified to
use bio_is_zone_append() to execute blk_zone_update_request_bio() for
both native and emulated zone append operations.
This commit contains contributions from Christoph Hellwig <hch@lst.de>.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-11-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Zone write plugging implements a per-zone "plug" for write operations
to control the submission and execution order of write operations to
sequential write required zones of a zoned block device. Per-zone
plugging guarantees that at any time there is at most only one write
request per zone being executed. This mechanism is intended to replace
zone write locking which implements a similar per-zone write throttling
at the scheduler level, but is implemented only by mq-deadline.
Unlike zone write locking which operates on requests, zone write
plugging operates on BIOs. A zone write plug is simply a BIO list that
is atomically manipulated using a spinlock and a kblockd submission
work. A write BIO to a zone is "plugged" to delay its execution if a
write BIO for the same zone was already issued, that is, if a write
request for the same zone is being executed. The next plugged BIO is
unplugged and issued once the write request completes.
This mechanism allows to:
- Untangle zone write ordering from block IO schedulers. This allows
removing the restriction on using mq-deadline for writing to zoned
block devices. Any block IO scheduler, including "none" can be used.
- Zone write plugging operates on BIOs instead of requests. Plugged
BIOs waiting for execution thus do not hold scheduling tags and thus
are not preventing other BIOs from executing (reads or writes to
other zones). Depending on the workload, this can significantly
improve the device use (higher queue depth operation) and
performance.
- Both blk-mq (request based) zoned devices and BIO-based zoned devices
(e.g. device mapper) can use zone write plugging. It is mandatory
for the former but optional for the latter. BIO-based drivers can
use zone write plugging to implement write ordering guarantees, or
the drivers can implement their own if needed.
- The code is less invasive in the block layer and is mostly limited to
blk-zoned.c with some small changes in blk-mq.c, blk-merge.c and
bio.c.
Zone write plugging is implemented using struct blk_zone_wplug. This
structure includes a spinlock, a BIO list and a work structure to
handle the submission of plugged BIOs. Zone write plugs structures are
managed using a per-disk hash table.
Plugging of zone write BIOs is done using the function
blk_zone_write_plug_bio() which returns false if a BIO execution does
not need to be delayed and true otherwise. This function is called
from blk_mq_submit_bio() after a BIO is split to avoid large BIOs
spanning multiple zones which would cause mishandling of zone write
plugs. This ichange enables by default zone write plugging for any mq
request-based block device. BIO-based device drivers can also use zone
write plugging by expliclty calling blk_zone_write_plug_bio() in their
->submit_bio method. For such devices, the driver must ensure that a
BIO passed to blk_zone_write_plug_bio() is already split and not
straddling zone boundaries.
Only write and write zeroes BIOs are plugged. Zone write plugging does
not introduce any significant overhead for other operations. A BIO that
is being handled through zone write plugging is flagged using the new
BIO flag BIO_ZONE_WRITE_PLUGGING. A request handling a BIO flagged with
this new flag is flagged with the new RQF_ZONE_WRITE_PLUGGING flag.
The completion of BIOs and requests flagged trigger respectively calls
to the functions blk_zone_write_bio_endio() and
blk_zone_write_complete_request(). The latter function is used to
trigger submission of the next plugged BIO using the zone plug work.
blk_zone_write_bio_endio() does the same for BIO-based devices.
This ensures that at any time, at most one request (blk-mq devices) or
one BIO (BIO-based devices) is being executed for any zone. The
handling of zone write plugs using a per-zone plug spinlock maximizes
parallelism and device usage by allowing multiple zones to be writen
simultaneously without lock contention.
Zone write plugging ignores flush BIOs without data. Hovever, any flush
BIO that has data is always plugged so that the write part of the flush
sequence is serialized with other regular writes.
Given that any BIO handled through zone write plugging will be the only
BIO in flight for the target zone when it is executed, the unplugging
and submission of a BIO will have no chance of successfully merging with
plugged requests or requests in the scheduler. To overcome this
potential performance degradation, blk_mq_submit_bio() calls the
function blk_zone_write_plug_attempt_merge() to try to merge other
plugged BIOs with the one just unplugged and submitted. Successful
merging is signaled using blk_zone_write_plug_bio_merged(), called from
bio_attempt_back_merge(). Furthermore, to avoid recalculating the number
of segments of plugged BIOs to attempt merging, the number of segments
of a plugged BIO is saved using the new struct bio field
__bi_nr_segments. To avoid growing the size of struct bio, this field is
added as a union with the bio_cookie field. This is safe to do as
polling is always disabled for plugged BIOs.
When BIOs are plugged in a zone write plug, the device request queue
usage counter is always incremented. This reference is kept and reused
for blk-mq devices when the plugged BIO is unplugged and submitted
again using submit_bio_noacct_nocheck(). For this case, the unplugged
BIO is already flagged with BIO_ZONE_WRITE_PLUGGING and
blk_mq_submit_bio() proceeds directly to allocating a new request for
the BIO, re-using the usage reference count taken when the BIO was
plugged. This extra reference count is dropped in
blk_zone_write_plug_attempt_merge() for any plugged BIO that is
successfully merged. Given that BIO-based devices will not take this
path, the extra reference is dropped after a plugged BIO is unplugged
and submitted.
Zone write plugs are dynamically allocated and managed using a hash
table (an array of struct hlist_head) with RCU protection.
A zone write plug is allocated when a write BIO is received for the
zone and not freed until the zone is fully written, reset or finished.
To detect when a zone write plug can be freed, the write state of each
zone is tracked using a write pointer offset which corresponds to the
offset of a zone write pointer relative to the zone start. Write
operations always increment this write pointer offset. Zone reset
operations set it to 0 and zone finish operations set it to the zone
size.
If a write error happens, the wp_offset value of a zone write plug may
become incorrect and out of sync with the device managed write pointer.
This is handled using the zone write plug flag BLK_ZONE_WPLUG_ERROR.
The function blk_zone_wplug_handle_error() is called from the new disk
zone write plug work when this flag is set. This function executes a
report zone to update the zone write pointer offset to the current
value as indicated by the device. The disk zone write plug work is
scheduled whenever a BIO flagged with BIO_ZONE_WRITE_PLUGGING completes
with an error or when bio_zone_wplug_prepare_bio() detects an unaligned
write. Once scheduled, the disk zone write plugs work keeps running
until all zone errors are handled.
To match the new data structures used for zoned disks, the function
disk_free_zone_bitmaps() is renamed to the more generic
disk_free_zone_resources(). The function disk_init_zone_resources() is
also introduced to initialize zone write plugs resources when a gendisk
is allocated.
In order to guarantee that the user can simultaneously write up to a
number of zones equal to a device max active zone limit or max open zone
limit, zone write plugs are allocated using a mempool sized to the
maximum of these 2 device limits. For a device that does not have
active and open zone limits, 128 is used as the default mempool size.
If a change to the device active and open zone limits is detected, the
disk mempool is resized when blk_revalidate_disk_zones() is executed.
This commit contains contributions from Christoph Hellwig <hch@lst.de>.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240408014128.205141-8-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove "static" from the definition of bio_attempt_back_merge() and
declare this function in block/blk.h to allow using it internally from
other block layer files. The definition of enum bio_merge_status is
also moved to block/blk.h.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240408014128.205141-6-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
On completion of a zone append request, the request sector indicates the
location of the written data. This value must be returned to the user
through the BIO iter sector. This is done in 2 places: in
blk_complete_request() and in blk_update_request(). Introduce the inline
helper function blk_zone_update_request_bio() to avoid duplicating
this BIO update for zone append requests, and to compile out this
helper call when CONFIG_BLK_DEV_ZONED is not enabled.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240408014128.205141-4-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since commit 8e756373d7 ("block: Move bio merge related functions into
blk-merge.c"), blk_rq_set_mixed_merge() has only been referenced in
blk-merge.c, so make it static.
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240325083501.2816408-1-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We should not have any callers of this from non-task context, but Jakub
ran [1] into one from blk-iocost. Rather than risk running into others,
or future ones, just limit blk_time_get_ns() to when it is called from
a task. Any other usage is invalid.
[1] https://lore.kernel.org/lkml/CAHk-=wiOaBLqarS2uFhM1YdwOvCX4CZaWkeyNDY1zONpbYw2ig@mail.gmail.com/
Fixes: da4c8c3d09 ("block: cache current nsec time in struct blk_plug")
Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We just need to use the holder to indicate whether a block device open
was exclusive or not. We did use to do that before but had to give that
up once we switched to struct bdev_handle. Before struct bdev_handle we
only stashed stuff in file->private_data if this was an exclusive open
but after struct bdev_handle we always set file->private_data to a
struct bdev_handle and so we had to use bdev_handle->mode or
bdev_handle->holder. Now that we don't use struct bdev_handle anymore we
can revert back to the old behavior.
Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-32-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
We can always go directly via:
* I_BDEV(bdev_file->f_inode)
* I_BDEV(bdev_file->f_mapping->host)
So keeping struct bdev in struct bdev_handle is redundant.
Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-30-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Move both of them to the private block header. There's no caller in the
tree anymore that uses them directly.
Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-28-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This is the same in two places, and another will be added soon. Create a
helper for it.
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240223155910.3622666-4-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass a queue_limits to blk_alloc_queue and apply it after validating and
capping the values using blk_validate_limits. This will allow allocating
queues with valid queue limits instead of setting the values one at a
time later.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240213073425.1621680-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new queue_limits_{start,commit}_update pair of functions that
allows taking an atomic snapshot of queue limits, update it, and
commit it if it passes validity checking. Also use the low-level
validation helper to implement blk_set_default_limits instead of
duplicating the initialization.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240213073425.1621680-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Mark the task as having a cached timestamp when set assign it, so we
can efficiently check if it needs updating post being scheduled back in.
This covers both the actual schedule out case, which would've flushed
the plug, and the preemption case which doesn't touch the plugged
requests (for many reasons, one of them being then we'd need to have
preemption disabled around plug state manipulation).
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Querying the current time is the most costly thing we do in the block
layer per IO, and depending on kernel config settings, we may do it
many times per IO.
None of the callers actually need nsec granularity. Take advantage of
that by caching the current time in the plug, with the assumption here
being that any time checking will be temporally close enough that the
slight loss of precision doesn't matter.
If the block plug gets flushed, eg on preempt or schedule out, then
we invalidate the cached clock.
On a basic peak IOPS test case with iostats enabled, this changes
the performance from:
IOPS=108.41M, BW=52.93GiB/s, IOS/call=31/31
IOPS=108.43M, BW=52.94GiB/s, IOS/call=32/32
IOPS=108.29M, BW=52.88GiB/s, IOS/call=31/32
IOPS=108.35M, BW=52.91GiB/s, IOS/call=32/32
IOPS=108.42M, BW=52.94GiB/s, IOS/call=31/31
IOPS=108.40M, BW=52.93GiB/s, IOS/call=32/32
IOPS=108.31M, BW=52.89GiB/s, IOS/call=32/31
to
IOPS=118.79M, BW=58.00GiB/s, IOS/call=31/32
IOPS=118.62M, BW=57.92GiB/s, IOS/call=31/31
IOPS=118.80M, BW=58.01GiB/s, IOS/call=32/31
IOPS=118.78M, BW=58.00GiB/s, IOS/call=32/32
IOPS=118.69M, BW=57.95GiB/s, IOS/call=32/31
IOPS=118.62M, BW=57.92GiB/s, IOS/call=32/31
IOPS=118.63M, BW=57.92GiB/s, IOS/call=31/32
which is more than a 9% improvement in performance. Looking at perf diff,
we can see a huge reduction in time overhead:
10.55% -9.88% [kernel.vmlinux] [k] read_tsc
1.31% -1.22% [kernel.vmlinux] [k] ktime_get
Note that since this relies on blk_plug for the caching, it's only
applicable to the issue side. But this is where most of the time calls
happen anyway. On the completion side, cached time stamping is done with
struct io_comp patch, as long as the driver supports it.
It's also worth noting that the above testing doesn't enable any of the
higher cost CPU items on the block layer side, like wbt, cgroups,
iocost, etc, which all would add additional time querying and hence
overhead. IOW, results would likely look even better in comparison with
those enabled, as distros would do.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Convert any user of ktime_get_ns() to use blk_time_get_ns(), and
ktime_get() to blk_time_get(), so we have a unified API for querying the
current time in nanoseconds or as ktime.
No functional changes intended, this patch just wraps ktime_get_ns()
and ktime_get() with a block helper.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for moving time keeping into blk.h, move the cgroup
related code for timestamps in here too. This will help avoid a circular
dependency, and also moves it into a more appropriate header as this one
is private to the block layer code.
Leave struct bio_issue in blk_types.h as it's a proper time definition.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Only use disk_set_zoned to actually enable zoned device support.
For clearing it, call disk_clear_zoned, which is renamed from
disk_clear_zone_settings and now directly clears the zoned flag as
well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20231217165359.604246-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
