Zone write plugging for handling writes to zones of a zoned block
device always execute a zone report whenever a write BIO to a zone
fails. The intent of this is to ensure that the tracking of a zone write
pointer is always correct to ensure that the alignment to a zone write
pointer of write BIOs can be checked on submission and that we can
always correctly emulate zone append operations using regular write
BIOs.
However, this error recovery scheme introduces a potential deadlock if a
device queue freeze is initiated while BIOs are still plugged in a zone
write plug and one of these write operation fails. In such case, the
disk zone write plug error recovery work is scheduled and executes a
report zone. This in turn can result in a request allocation in the
underlying driver to issue the report zones command to the device. But
with the device queue freeze already started, this allocation will
block, preventing the report zone execution and the continuation of the
processing of the plugged BIOs. As plugged BIOs hold a queue usage
reference, the queue freeze itself will never complete, resulting in a
deadlock.
Avoid this problem by completely removing from the zone write plugging
code the use of report zones operations after a failed write operation,
instead relying on the device user to either execute a report zones,
reset the zone, finish the zone, or give up writing to the device (which
is a fairly common pattern for file systems which degrade to read-only
after write failures). This is not an unreasonnable requirement as all
well-behaved applications, FSes and device mapper already use report
zones to recover from write errors whenever possible by comparing the
current position of a zone write pointer with what their assumption
about the position is.
The changes to remove the automatic error recovery are as follows:
- Completely remove the error recovery work and its associated
resources (zone write plug list head, disk error list, and disk
zone_wplugs_work work struct). This also removes the functions
disk_zone_wplug_set_error() and disk_zone_wplug_clear_error().
- Change the BLK_ZONE_WPLUG_ERROR zone write plug flag into
BLK_ZONE_WPLUG_NEED_WP_UPDATE. This new flag is set for a zone write
plug whenever a write opration targetting the zone of the zone write
plug fails. This flag indicates that the zone write pointer offset is
not reliable and that it must be updated when the next report zone,
reset zone, finish zone or disk revalidation is executed.
- Modify blk_zone_write_plug_bio_endio() to set the
BLK_ZONE_WPLUG_NEED_WP_UPDATE flag for the target zone of a failed
write BIO.
- Modify the function disk_zone_wplug_set_wp_offset() to clear this
new flag, thus implementing recovery of a correct write pointer
offset with the reset (all) zone and finish zone operations.
- Modify blkdev_report_zones() to always use the disk_report_zones_cb()
callback so that disk_zone_wplug_sync_wp_offset() can be called for
any zone marked with the BLK_ZONE_WPLUG_NEED_WP_UPDATE flag.
This implements recovery of a correct write pointer offset for zone
write plugs marked with BLK_ZONE_WPLUG_NEED_WP_UPDATE and within
the range of the report zones operation executed by the user.
- Modify blk_revalidate_seq_zone() to call
disk_zone_wplug_sync_wp_offset() for all sequential write required
zones when a zoned block device is revalidated, thus always resolving
any inconsistency between the write pointer offset of zone write
plugs and the actual write pointer position of sequential zones.
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20241209122357.47838-5-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The zone reclaim processing of the dm-zoned device mapper uses
blkdev_issue_zeroout() to align the write pointer of a zone being used
for reclaiming another zone, to write the valid data blocks from the
zone being reclaimed at the same position relative to the zone start in
the reclaim target zone.
The first call to blkdev_issue_zeroout() will try to use hardware
offload using a REQ_OP_WRITE_ZEROES operation if the device reports a
non-zero max_write_zeroes_sectors queue limit. If this operation fails
because of the lack of hardware support, blkdev_issue_zeroout() falls
back to using a regular write operation with the zero-page as buffer.
Currently, such REQ_OP_WRITE_ZEROES failure is automatically handled by
the block layer zone write plugging code which will execute a report
zones operation to ensure that the write pointer of the target zone of
the failed operation has not changed and to "rewind" the zone write
pointer offset of the target zone as it was advanced when the write zero
operation was submitted. So the REQ_OP_WRITE_ZEROES failure does not
cause any issue and blkdev_issue_zeroout() works as expected.
However, since the automatic recovery of zone write pointers by the zone
write plugging code can potentially cause deadlocks with queue freeze
operations, a different recovery must be implemented in preparation for
the removal of zone write plugging report zones based recovery.
Do this by introducing the new function blk_zone_issue_zeroout(). This
function first calls blkdev_issue_zeroout() with the flag
BLKDEV_ZERO_NOFALLBACK to intercept failures on the first execution
which attempt to use the device hardware offload with the
REQ_OP_WRITE_ZEROES operation. If this attempt fails, a report zone
operation is issued to restore the zone write pointer offset of the
target zone to the correct position and blkdev_issue_zeroout() is called
again without the BLKDEV_ZERO_NOFALLBACK flag. The report zones
operation performing this recovery is implemented using the helper
function disk_zone_sync_wp_offset() which calls the gendisk report_zones
file operation with the callback disk_report_zones_cb(). This callback
updates the target write pointer offset of the target zone using the new
function disk_zone_wplug_sync_wp_offset().
dmz_reclaim_align_wp() is modified to change its call to
blkdev_issue_zeroout() to a call to blk_zone_issue_zeroout() without any
other change needed as the two functions are functionnally equivalent.
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20241209122357.47838-4-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There are currently any issuer of REQ_OP_ZONE_RESET and
REQ_OP_ZONE_FINISH operations that set REQ_NOWAIT. However, as we cannot
handle this flag correctly due to the potential request allocation
failure that may happen in blk_mq_submit_bio() after blk_zone_plug_bio()
has handled the zone write plug write pointer updates for the targeted
zones, modify blk_zone_wplug_handle_reset_or_finish() to warn if this
flag is set and ignore it.
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20241209122357.47838-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For zoned block devices, a write BIO issued to a zone that has no
on-going writes will be prepared for execution and allowed to execute
immediately by blk_zone_wplug_handle_write() (called from
blk_zone_plug_bio()). However, if this BIO specifies REQ_NOWAIT, the
allocation of a request for its execution in blk_mq_submit_bio() may
fail after blk_zone_plug_bio() completed, marking the target zone of the
BIO as plugged. When this BIO is retried later on, it will be blocked as
the zone write plug of the target zone is in a plugged state without any
on-going write operation (completion of write operations trigger
unplugging of the next write BIOs for a zone). This leads to a BIO that
is stuck in a zone write plug and never completes, which results in
various issues such as hung tasks.
Avoid this problem by always executing REQ_NOWAIT write BIOs using the
BIO work of a zone write plug. This ensure that we never block the BIO
issuer and can thus safely ignore the REQ_NOWAIT flag when executing the
BIO from the zone write plug BIO work.
Since such BIO may be the first write BIO issued to a zone with no
on-going write, modify disk_zone_wplug_add_bio() to schedule the zone
write plug BIO work if the write plug is not already marked with the
BLK_ZONE_WPLUG_PLUGGED flag. This scheduling is otherwise not necessary
as the completion of the on-going write for the zone will schedule the
execution of the next plugged BIOs.
blk_zone_wplug_handle_write() is also fixed to better handle zone write
plug allocation failures for REQ_NOWAIT BIOs by failing a write BIO
using bio_wouldblock_error() instead of bio_io_error().
Reported-by: Bart Van Assche <bvanassche@acm.org>
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20241209122357.47838-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The function blk_revalidate_disk_zones() calls the function
disk_update_zone_resources() after freezing the device queue. In turn,
disk_update_zone_resources() calls queue_limits_start_update() which
takes a queue limits mutex lock, resulting in the ordering:
q->q_usage_counter check -> q->limits_lock. However, the usual ordering
is to always take a queue limit lock before freezing the queue to commit
the limits updates, e.g., the code pattern:
lim = queue_limits_start_update(q);
...
blk_mq_freeze_queue(q);
ret = queue_limits_commit_update(q, &lim);
blk_mq_unfreeze_queue(q);
Thus, blk_revalidate_disk_zones() introduces a potential circular
locking dependency deadlock that lockdep sometimes catches with the
splat:
[ 51.934109] ======================================================
[ 51.935916] WARNING: possible circular locking dependency detected
[ 51.937561] 6.12.0+ #2107 Not tainted
[ 51.938648] ------------------------------------------------------
[ 51.940351] kworker/u16:4/157 is trying to acquire lock:
[ 51.941805] ffff9fff0aa0bea8 (&q->limits_lock){+.+.}-{4:4}, at: disk_update_zone_resources+0x86/0x170
[ 51.944314]
but task is already holding lock:
[ 51.945688] ffff9fff0aa0b890 (&q->q_usage_counter(queue)#3){++++}-{0:0}, at: blk_revalidate_disk_zones+0x15f/0x340
[ 51.948527]
which lock already depends on the new lock.
[ 51.951296]
the existing dependency chain (in reverse order) is:
[ 51.953708]
-> #1 (&q->q_usage_counter(queue)#3){++++}-{0:0}:
[ 51.956131] blk_queue_enter+0x1c9/0x1e0
[ 51.957290] blk_mq_alloc_request+0x187/0x2a0
[ 51.958365] scsi_execute_cmd+0x78/0x490 [scsi_mod]
[ 51.959514] read_capacity_16+0x111/0x410 [sd_mod]
[ 51.960693] sd_revalidate_disk.isra.0+0x872/0x3240 [sd_mod]
[ 51.962004] sd_probe+0x2d7/0x520 [sd_mod]
[ 51.962993] really_probe+0xd5/0x330
[ 51.963898] __driver_probe_device+0x78/0x110
[ 51.964925] driver_probe_device+0x1f/0xa0
[ 51.965916] __driver_attach_async_helper+0x60/0xe0
[ 51.967017] async_run_entry_fn+0x2e/0x140
[ 51.968004] process_one_work+0x21f/0x5a0
[ 51.968987] worker_thread+0x1dc/0x3c0
[ 51.969868] kthread+0xe0/0x110
[ 51.970377] ret_from_fork+0x31/0x50
[ 51.970983] ret_from_fork_asm+0x11/0x20
[ 51.971587]
-> #0 (&q->limits_lock){+.+.}-{4:4}:
[ 51.972479] __lock_acquire+0x1337/0x2130
[ 51.973133] lock_acquire+0xc5/0x2d0
[ 51.973691] __mutex_lock+0xda/0xcf0
[ 51.974300] disk_update_zone_resources+0x86/0x170
[ 51.975032] blk_revalidate_disk_zones+0x16c/0x340
[ 51.975740] sd_zbc_revalidate_zones+0x73/0x160 [sd_mod]
[ 51.976524] sd_revalidate_disk.isra.0+0x465/0x3240 [sd_mod]
[ 51.977824] sd_probe+0x2d7/0x520 [sd_mod]
[ 51.978917] really_probe+0xd5/0x330
[ 51.979915] __driver_probe_device+0x78/0x110
[ 51.981047] driver_probe_device+0x1f/0xa0
[ 51.982143] __driver_attach_async_helper+0x60/0xe0
[ 51.983282] async_run_entry_fn+0x2e/0x140
[ 51.984319] process_one_work+0x21f/0x5a0
[ 51.985873] worker_thread+0x1dc/0x3c0
[ 51.987289] kthread+0xe0/0x110
[ 51.988546] ret_from_fork+0x31/0x50
[ 51.989926] ret_from_fork_asm+0x11/0x20
[ 51.991376]
other info that might help us debug this:
[ 51.994127] Possible unsafe locking scenario:
[ 51.995651] CPU0 CPU1
[ 51.996694] ---- ----
[ 51.997716] lock(&q->q_usage_counter(queue)#3);
[ 51.998817] lock(&q->limits_lock);
[ 52.000043] lock(&q->q_usage_counter(queue)#3);
[ 52.001638] lock(&q->limits_lock);
[ 52.002485]
*** DEADLOCK ***
Prevent this issue by moving the calls to blk_mq_freeze_queue() and
blk_mq_unfreeze_queue() around the call to queue_limits_commit_update()
in disk_update_zone_resources(). In case of revalidation failure, the
call to disk_free_zone_resources() in blk_revalidate_disk_zones()
is still done with the queue frozen as before.
Fixes: 843283e96e ("block: Fake max open zones limit when there is no limit")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241126104705.183996-1-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Turn the private disk_zone_is_conv() function in blk-zoned.c into a
public and documented bdev_zone_is_seq() helper with the inverse
polarity of the original function, also adding a check for non-zoned
devices so that all file systems can use the helper, even with a regular
block device.
Suggested-by: Christoph Hellwig <hch@lst.de>
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/20241107064300.227731-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Ensure that a disk revalidation changing the conventional zones bitmap
of a disk does not cause invalid memory references when using the
disk_zone_is_conv() helper by RCU protecting the disk->conv_zones_bitmap
pointer.
disk_zone_is_conv() is modified to operate under the RCU read lock and
the function disk_set_conv_zones_bitmap() is added to update a disk
conv_zones_bitmap pointer using rcu_replace_pointer() with the disk
zone_wplugs_lock spinlock held.
disk_free_zone_resources() is modified to call
disk_update_zone_resources() with a NULL bitmap pointer to free the disk
conv_zones_bitmap. disk_set_conv_zones_bitmap() is also used in
disk_update_zone_resources() to set the new (revalidated) bitmap and
free the old one.
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/20241107064300.227731-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With the lock layer zone append emulation, we are now always setting a
max_zone_append_sectors value for zoned devices and this check can't
ever trigger.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241104073955.112324-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-6.11/block-20240710' of git://git.kernel.dk/linux
Pull block updates from Jens Axboe:
- NVMe updates via Keith:
- Device initialization memory leak fixes (Keith)
- More constants defined (Weiwen)
- Target debugfs support (Hannes)
- PCIe subsystem reset enhancements (Keith)
- Queue-depth multipath policy (Redhat and PureStorage)
- Implement get_unique_id (Christoph)
- Authentication error fixes (Gaosheng)
- MD updates via Song
- sync_action fix and refactoring (Yu Kuai)
- Various small fixes (Christoph Hellwig, Li Nan, and Ofir Gal, Yu
Kuai, Benjamin Marzinski, Christophe JAILLET, Yang Li)
- Fix loop detach/open race (Gulam)
- Fix lower control limit for blk-throttle (Yu)
- Add module descriptions to various drivers (Jeff)
- Add support for atomic writes for block devices, and statx reporting
for same. Includes SCSI and NVMe (John, Prasad, Alan)
- Add IO priority information to block trace points (Dongliang)
- Various zone improvements and tweaks (Damien)
- mq-deadline tag reservation improvements (Bart)
- Ignore direct reclaim swap writes in writeback throttling (Baokun)
- Block integrity improvements and fixes (Anuj)
- Add basic support for rust based block drivers. Has a dummy null_blk
variant for now (Andreas)
- Series converting driver settings to queue limits, and cleanups and
fixes related to that (Christoph)
- Cleanup for poking too deeply into the bvec internals, in preparation
for DMA mapping API changes (Christoph)
- Various minor tweaks and fixes (Jiapeng, John, Kanchan, Mikulas,
Ming, Zhu, Damien, Christophe, Chaitanya)
* tag 'for-6.11/block-20240710' of git://git.kernel.dk/linux: (206 commits)
floppy: add missing MODULE_DESCRIPTION() macro
loop: add missing MODULE_DESCRIPTION() macro
ublk_drv: add missing MODULE_DESCRIPTION() macro
xen/blkback: add missing MODULE_DESCRIPTION() macro
block/rnbd: Constify struct kobj_type
block: take offset into account in blk_bvec_map_sg again
block: fix get_max_segment_size() warning
loop: Don't bother validating blocksize
virtio_blk: Don't bother validating blocksize
null_blk: Don't bother validating blocksize
block: Validate logical block size in blk_validate_limits()
virtio_blk: Fix default logical block size fallback
nvmet-auth: fix nvmet_auth hash error handling
nvme: implement ->get_unique_id
block: pass a phys_addr_t to get_max_segment_size
block: add a bvec_phys helper
blk-lib: check for kill signal in ioctl BLKZEROOUT
block: limit the Write Zeroes to manually writing zeroes fallback
block: refacto blkdev_issue_zeroout
block: move read-only and supported checks into (__)blkdev_issue_zeroout
...
Remove the helper function blk_alloc_zone_bitmap() and replace its
single call site with a call to bitmap_alloc(). To be consistent with
this change, use bitmap_free() to free a disk convnetional zone bitmap.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240704052816.623865-6-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that device mapper can handle resetting all zones of a mapped zoned
device using REQ_OP_ZONE_RESET_ALL, all zoned block device drivers
support this operation. With this, the request queue feature
BLK_FEAT_ZONE_RESETALL is not necessary and the emulation code in
blk-zone.c can be removed.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240704052816.623865-5-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is no need for bdev_nr_zones() to be an exported function
calculating the number of zones of a block device. Instead, given that
all callers use this helper with a fully initialized block device that
has a gendisk, we can redefine this function as an inline helper in
blkdev.h.
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/20240621031506.759397-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Make sure that the zone resource limits of a zoned block device are
correct by checking that:
(a) If the device has a max active zones limit, make sure that the max
open zones limit is lower than the max active zones limit.
(b) If the device has zone resource limits, check that the limits
values are lower than the number of sequential zones of the device.
If it is not, assume that the zoned device has no limits by setting
the limits to 0.
For (a), a check is added to blk_validate_zoned_limits() and an error
returned if the max open zones limit exceeds the value of the max active
zone limit (if there is one).
For (b), given that we need the number of sequential zones of the zoned
device, this check is added to disk_update_zone_resources(). This is
safe to do as that function is executed with the disk queue frozen and
the check executed after queue_limits_start_update() which takes the
queue limits lock. Of note is that the early return in this function
for zoned devices that do not use zone write plugging (e.g. DM devices
using native zone append) is moved to after the new check and adjustment
of the zone resource limits so that the check applies to any zoned
device.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
Link: https://lore.kernel.org/r/20240611023639.89277-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For zoned block devices using zone write plugging, an rcu_barrier() call
is needed in disk_free_zone_resources() to synchronize freeing of zone
write plugs and the destrution of the mempool used to allocate the
plugs. The barrier call does slow down a little teardown of zoned block
devices but should not affect teardown of regular block devices or zoned
block devices that do not use zone write plugging (e.g. zoned DM devices
that do not require zone append emulation).
Modify disk_free_zone_resources() to return early if we do not have a
mempool to start with, that is, if the device does not use zone write
plugging. This avoids the costly rcu_barrier() and speeds up disk
teardown.
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Link: https://lore.kernel.org/r/20240607002126.104227-1-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A zoned device may have a last sequential write required zone that is
smaller than other zones. However, all tests to check if a zone write
plug write offset exceeds the zone capacity use the same capacity
value stored in the gendisk zone_capacity field. This is incorrect for a
zoned device with a last runt (smaller) zone.
Add the new field last_zone_capacity to struct gendisk to store the
capacity of the last zone of the device. blk_revalidate_seq_zone() and
blk_revalidate_conv_zone() are both modified to get this value when
disk_zone_is_last() returns true. Similarly to zone_capacity, the value
is first stored using the last_zone_capacity field of struct
blk_revalidate_zone_args. Once zone revalidation of all zones is done,
this is used to set the gendisk last_zone_capacity field.
The checks to determine if a zone is full or if a sector offset in a
zone exceeds the zone capacity in disk_should_remove_zone_wplug(),
disk_zone_wplug_abort_unaligned(), blk_zone_write_plug_init_request(),
and blk_zone_wplug_prepare_bio() are modified to use the new helper
functions disk_zone_is_full() and disk_zone_wplug_is_full().
disk_zone_is_full() uses the zone index to determine if the zone being
tested is the last one of the disk and uses the either the disk
zone_capacity or last_zone_capacity accordingly.
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Link: https://lore.kernel.org/r/20240530054035.491497-4-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit ecfe43b11b ("block: Remember zone capacity when revalidating
zones") introduced checks to ensure that the capacity of the zones of
a zoned device is constant for all zones. However, this check ignores
the possibility that a zoned device has a smaller last zone with a size
not equal to the capacity of other zones. Such device correspond in
practice to an SMR drive with a smaller last zone and all zones with a
capacity equal to the zone size, leading to the last zone capacity being
different than the capacity of other zones.
Correctly handle such device by fixing the check for the constant zone
capacity in blk_revalidate_seq_zone() using the new helper function
disk_zone_is_last(). This helper function is also used in
blk_revalidate_zone_cb() when checking the zone size.
Fixes: ecfe43b11b ("block: Remember zone capacity when revalidating zones")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Link: https://lore.kernel.org/r/20240530054035.491497-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We can easily have up to 24 flags with sane
atomicity, _without_ pushing anything out
of the first cacheline of struct block_device.
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Merge tag 'pull-bd_flags-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull bdev flags update from Al Viro:
"Compactifying bdev flags.
We can easily have up to 24 flags with sane atomicity, _without_
pushing anything out of the first cacheline of struct block_device"
* tag 'pull-bd_flags-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
bdev: move ->bd_make_it_fail to ->__bd_flags
bdev: move ->bd_ro_warned to ->__bd_flags
bdev: move ->bd_has_subit_bio to ->__bd_flags
bdev: move ->bd_write_holder into ->__bd_flags
bdev: move ->bd_read_only to ->__bd_flags
bdev: infrastructure for flags
wrapper for access to ->bd_partno
Use bdev_is_paritition() instead of open-coding it
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
Define the code for checking conventional and sequential write required
zones suing the functions blk_revalidate_conv_zone() and
blk_revalidate_seq_zone() respectively. This simplifies the zone type
switch-case in blk_revalidate_zone_cb().
No functional changes.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240501110907.96950-15-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When BIOs plugged in a zone write plug are aborted,
blk_zone_wplug_bio_io_error() clears the BIO BIO_ZONE_WRITE_PLUGGING
flag so that bio_io_error(bio) does not end up calling
blk_zone_write_plug_bio_endio() and we thus need to manually drop the
reference on the zone write plug held by the aborted BIO.
Move the call to disk_put_zone_wplug() that is alwasy following the call
to blk_zone_wplug_bio_io_error() inside that function to simplify the
code.
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/20240501110907.96950-14-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We already have the disk variable obtained from the bio when calling
disk_get_zone_wplug(). So use that variable instead of dereferencing the
bio bdev again for the disk argument of disk_get_zone_wplug().
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/20240501110907.96950-13-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
Improve blk_zone_write_plug_bio_merged() to check that we succefully get
a reference on the zone write plug of the merged BIO, as expected since
for a merge we already have at least one request and one BIO referencing
the zone write plug. Comments in this function are also improved to
better explain the references to the BIO zone write plug.
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/20240501110907.96950-11-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>
Large write BIOs that span a zone boundary are split in
blk_mq_submit_bio() before being passed to blk_zone_plug_bio() for zone
write plugging. Such split BIO will be chained with one fragment
targeting one zone and the remainder of the BIO targeting the next
zone. The two BIOs can be executed in parallel, without a predetermine
order relative to eachother and their completion may be reversed: the
remainder first completing and the first fragment then completing. In
such case, bio_endio() will not immediately execute
blk_zone_write_plug_bio_endio() for the parent BIO (the remainder of the
split BIO) as the BIOs are chained. blk_zone_write_plug_bio_endio() for
the parent BIO will be executed only once the first fragment completes.
In the case of a device with small zones and very large BIOs, uch
completion pattern can lead to disk_should_remove_zone_wplug() to return
true for the zone of the parent BIO when the parent BIO request
completes and blk_zone_write_plug_complete_request() is executed. This
triggers the removal of the zone write plug from the hash table using
disk_remove_zone_wplug(). With the zone write plug of the parent BIO
missing, the call to disk_get_zone_wplug() in
blk_zone_write_plug_bio_endio() returns NULL and triggers a warning.
This patterns can be recreated fairly easily using a scsi_debug device
with small zone and btrfs. E.g.
modprobe scsi_debug delay=0 dev_size_mb=1024 sector_size=4096 \
zbc=host-managed zone_cap_mb=3 zone_nr_conv=0 zone_size_mb=4
mkfs.btrfs -f -O zoned /dev/sda
mount -t btrfs /dev/sda /mnt
fio --name=wrtest --rw=randwrite --direct=1 --ioengine=libaio \
--bs=4k --iodepth=16 --size=1M --directory=/mnt --time_based \
--runtime=10
umount /dev/sda
Will result in the warning:
[ 29.035538] WARNING: CPU: 3 PID: 37 at block/blk-zoned.c:1207 blk_zone_write_plug_bio_endio+0xee/0x1e0
...
[ 29.058682] Call Trace:
[ 29.059095] <TASK>
[ 29.059473] ? __warn+0x80/0x120
[ 29.059983] ? blk_zone_write_plug_bio_endio+0xee/0x1e0
[ 29.060728] ? report_bug+0x160/0x190
[ 29.061283] ? handle_bug+0x36/0x70
[ 29.061830] ? exc_invalid_op+0x17/0x60
[ 29.062399] ? asm_exc_invalid_op+0x1a/0x20
[ 29.063025] ? blk_zone_write_plug_bio_endio+0xee/0x1e0
[ 29.063760] bio_endio+0xb7/0x150
[ 29.064280] btrfs_clone_write_end_io+0x2b/0x60 [btrfs]
[ 29.065049] blk_update_request+0x17c/0x500
[ 29.065666] scsi_end_request+0x27/0x1a0 [scsi_mod]
[ 29.066356] scsi_io_completion+0x5b/0x690 [scsi_mod]
[ 29.067077] blk_complete_reqs+0x3a/0x50
[ 29.067692] __do_softirq+0xcf/0x2b3
[ 29.068248] ? sort_range+0x20/0x20
[ 29.068791] run_ksoftirqd+0x1c/0x30
[ 29.069339] smpboot_thread_fn+0xcc/0x1b0
[ 29.069936] kthread+0xcf/0x100
[ 29.070438] ? kthread_complete_and_exit+0x20/0x20
[ 29.071314] ret_from_fork+0x31/0x50
[ 29.071873] ? kthread_complete_and_exit+0x20/0x20
[ 29.072563] ret_from_fork_asm+0x11/0x20
[ 29.073146] </TASK>
either when fio executes or when unmount is executed.
Fix this by modifying disk_should_remove_zone_wplug() to check that the
reference count to a zone write plug is not larger than 2, that is, that
the only references left on the zone are the caller held reference
(blk_zone_write_plug_complete_request()) and the initial extra reference
for the zone write plug taken when it was initialized (and that is
dropped when the zone write plug is removed from the hash table).
To be consistent with this change, make sure to drop the request or BIO
held reference to the zone write plug before calling
disk_zone_wplug_unplug_bio(). All references are also dropped using
disk_put_zone_wplug() instead of atomic_dec() to ensure that the zone
write plug is freed if it needs to be.
Comments are also improved to clarify zone write plugs reference
handling.
Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240501110907.96950-8-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix disk_remove_zone_wplug() to ensure that a zone write plug already
removed from a disk hash table of zone write plugs is not removed
again. Do this by checking the BLK_ZONE_WPLUG_UNHASHED flag of the plug
and calling hlist_del_init_rcu() only if the flag is not set.
Furthermore, since BIO completions can happen at any time, that is,
decrementing of the zone write plug reference count can happen at any
time, make sure to use disk_put_zone_wplug() instead of atomic_dec() to
ensure that the zone write plug is freed when its last reference is
dropped. In order to do this, disk_remove_zone_wplug() is moved after
the definition of disk_put_zone_wplug(). disk_should_remove_zone_wplug()
is moved as well to keep it together with disk_remove_zone_wplug().
To be consistent with this change, add a check in disk_put_zone_wplug()
to ensure that a zone write plug being freed was already removed from
the disk hash table.
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/20240501110907.96950-7-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since a zone write plug BIO work is a field of struct blk_zone_wplug, we
must ensure that a zone write plug is never freed when its BIO
submission work is queued or running. Do this by holding a reference on
the zone write plug when the submission work is scheduled for execution
with queue_work() and releasing the reference at the end of the
execution of the work function blk_zone_wplug_bio_work().
The helper function disk_zone_wplug_schedule_bio_work() is introduced to
get a reference on a zone write plug and queue its work. This helper is
used in disk_zone_wplug_unplug_bio() and disk_zone_wplug_handle_error().
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/20240501110907.96950-6-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When zone is reset or finished, disk_zone_wplug_set_wp_offset() is
called to update the zone write plug write pointer offset and to clear
the zone error state (BLK_ZONE_WPLUG_ERROR flag) if it is set.
However, this processing is missing dropping the reference to the zone
write plug that was taken in disk_zone_wplug_set_error() when the error
flag was first set. Furthermore, the error state handling must release
the zone write plug lock to first execute a report zones command. When
the report zone races with a reset or finish operation that clears the
error, we can end up decrementing the zone write plug reference count
twice: once in disk_zone_wplug_set_wp_offset() for the reset/finish
operation and one more time in disk_zone_wplugs_work() once
disk_zone_wplug_handle_error() completes.
Fix this by introducing disk_zone_wplug_clear_error() as the symmetric
function of disk_zone_wplug_set_error(). disk_zone_wplug_clear_error()
decrements the zone write plug reference count obtained in
disk_zone_wplug_set_error() only if the error handling has not started
yet, that is, only if disk_zone_wplugs_work() has not yet taken the zone
write plug off the error list. This ensure that either
disk_zone_wplug_clear_error() or disk_zone_wplugs_work() drop the zone
write plug reference count.
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/20240501110907.96950-5-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When revalidating the zones of a zoned block device,
blk_revalidate_zone_cb() must allocate a zone write plug for any
sequential write required zone that is not empty nor full. However, the
current code tests the latter case by comparing the zone write pointer
offset to the zone size instead of the zone capacity. Furthermore,
disk_get_and_lock_zone_wplug() is called with a sector argument equal to
the zone start instead of the current zone write pointer position.
This commit fixes both issues by calling disk_get_and_lock_zone_wplug()
for a zone that is not empty and with a write pointer offset lower than
the zone capacity and use the zone capacity sector as the sector
argument for disk_get_and_lock_zone_wplug().
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/20240501110907.96950-4-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For a device that has no limits for the maximum number of open and
active zones, we default to using the number of zones, limited to
BLK_ZONE_WPLUG_DEFAULT_POOL_SIZE (128), for the maximum number of open
zones indicated to the user. However, for a device that has conventional
zones and less zones than BLK_ZONE_WPLUG_DEFAULT_POOL_SIZE, we should
not account conventional zones and set the limit to the number of
sequential write required zones. Furthermore, for cases where the limit
is equal to the number of sequential write required zones, we can
advertize a limit of 0 to indicate "no limits".
Fix this by moving the zone write plug mempool resizing from
disk_revalidate_zone_resources() to disk_update_zone_resources() where
we can safely compute the number of conventional zones and update the
limits.
Fixes: 843283e96e ("block: Fake max open zones limit when there is no limit")
Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
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/20240501110907.96950-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Changhui reported a kernel crash when running this simple shell
reproducer:
# cd /sys/kernel/debug/block && find . -type f -exec grep -aH . {} \;
The above results in a NULL pointer dereference if a device does not have
a zone_wplugs_hash allocated.
To fix this, return early if we don't have a zone_wplugs_hash.
Reported-by: Changhui Zhong <czhong@redhat.com>
Fixes: a98b05b02f ("block: Replace zone_wlock debugfs entry with zone_wplugs entry")
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/e5fec079dfca448cc21c425cfa5d7b291f5faa67.1714046443.git.johannes.thumshirn@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A zone write plug BIO work function blk_zone_wplug_bio_work() calls
submit_bio_noacct_nocheck() to execute the next unplugged BIO. This
function may block. So executing zone plugs BIO works using the block
layer global kblockd workqueue can potentially lead to preformance or
latency issues as the number of concurrent work for a workqueue is
limited to WQ_DFL_ACTIVE (256).
1) For a system with a large number of zoned disks, issuing write
requests to otherwise unused zones may be delayed wiating for a work
thread to become available.
2) Requeue operations which use kblockd but are independent of zone
write plugging may alsoi end up being delayed.
To avoid these potential performance issues, create a workqueue per
zoned device to execute zone plugs BIO work. The workqueue max active
parameter is set to the maximum number of zone write plugs allocated
with the zone write plug mempool. This limit is equal to the maximum
number of open zones of the disk and defaults to 128 for disks that do
not have a limit on the number of open zones.
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240420075811.1276893-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Zone write locking is now unused and replaced with zone write plugging.
Remove all code that was implementing zone write locking, that is, the
various helper functions controlling request zone write locking and
the gendisk attached zone bitmaps.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.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>
Link: https://lore.kernel.org/r/20240408014128.205141-27-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation to completely remove zone write locking, replace the
"zone_wlock" mq-debugfs entry that was listing zones that are
write-locked with the zone_wplugs entry which lists the zones that
currently have a write plug allocated.
The write plug information provided is: the zone number, the zone write
plug flags, the zone write plug write pointer offset and the number of
BIOs currently waiting for execution in the zone write plug BIO list.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
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>
Link: https://lore.kernel.org/r/20240408014128.205141-26-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block/blk-mq-debugfs-zone.c contains a single debugfs attribute
function. Defining this outside of block/blk-zoned.c does not really
help in any way, so move this zone related debugfs attribute to
block/blk-zoned.c and delete block/blk-mq-debugfs-zone.c.
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/20240408014128.205141-25-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The only user of blk_revalidate_disk_zones() second argument was the
SCSI disk driver (sd). Now that this driver does not require this
update_driver_data argument, remove it to simplify the interface of
blk_revalidate_disk_zones(). Also update the function kdoc comment to
be more accurate (i.e. there is no gendisk ->revalidate method).
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/20240408014128.205141-21-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for allowing BIO based device drivers to use zone write
plugging and its zone append emulation, allow these drivers to call
blk_revalidate_disk_zones() so that all zone resources necessary to zone
write plugging can be initialized.
To do so, remove the check in blk_revalidate_disk_zones() restricting
the use of this function to mq request-based drivers to allow also
BIO-based drivers to use it. This is safe to do as long as the
BIO-based block device queue is already setup and usable, as it should,
and can be safely frozen.
The helper function disk_need_zone_resources() is added to control the
allocation and initialization of the zone write plug hash table and
of the conventional zone bitmap only for mq devices and for BIO-based
devices that require zone append emulation.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.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/20240408014128.205141-12-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>
In preparation for adding a generic zone append emulation using zone
write plugging, allow device drivers supporting zoned block device to
set a the max_zone_append_sectors queue limit of a device to 0 to
indicate the lack of native support for zone append operations and that
the block layer should emulate these operations using regular write
operations.
blk_queue_max_zone_append_sectors() is modified to allow passing 0 as
the max_zone_append_sectors argument. The function
queue_max_zone_append_sectors() is also modified to ensure that the
minimum of the max_hw_sectors and chunk_sectors limit is used whenever
the max_zone_append_sectors limit is 0. This minimum is consistent with
the value set for the max_zone_append_sectors limit by the function
blk_validate_zoned_limits() when limits for a queue are validated.
The helper functions queue_emulates_zone_append() and
bdev_emulates_zone_append() are added to test if a queue (or block
device) emulates zone append operations.
In order for blk_revalidate_disk_zones() to accept zoned block devices
relying on zone append emulation, the direct check to the
max_zone_append_sectors queue limit of the disk is replaced by a check
using the value returned by queue_max_zone_append_sectors(). Similarly,
queue_zone_append_max_show() is modified to use the same accessor so
that the sysfs attribute advertizes the non-zero limit that will be
used, regardless if it is for native or emulated commands.
For stacking drivers, a top device should not need to care if the
underlying devices have native or emulated zone append operations.
blk_stack_limits() is thus modified to set the top device
max_zone_append_sectors limit using the new accessor
queue_limits_max_zone_append_sectors(). queue_max_zone_append_sectors()
is modified to use this function as well. Stacking drivers that require
zone append emulation, e.g. dm-crypt, can still request this feature by
calling blk_queue_max_zone_append_sectors() with a 0 limit.
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/20240408014128.205141-10-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For a zoned block device that has no limit on the number of open zones
and no limit on the number of active zones, the zone write plug mempool
is created with a size of 128 zone write plugs. For such case, set the
device max_open_zones queue limit to this value to indicate to the user
the potential performance penalty that may happen when writing
simultaneously to more zones than the mempool size.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.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/20240408014128.205141-9-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>
In preparation for adding zone write plugging, modify
blk_revalidate_disk_zones() to get the capacity of zones of a zoned
block device. This capacity value as a number of 512B sectors is stored
in the gendisk zone_capacity field.
Given that host-managed SMR disks (including zoned UFS drives) and all
known NVMe ZNS devices have the same zone capacity for all zones
blk_revalidate_disk_zones() returns an error if different capacities are
detected for different zones.
This also adds check to verify that the values reported by the device
for zone capacities are correct, that is, that the zone capacity is
never 0, does not exceed the zone size and is equal to the zone size for
conventional zones.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.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/20240408014128.205141-7-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The block zone code does not use RB-tree. So remove the include of
linux/rbtree.h as it is not needed.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240222131724.1803520-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that all callers pass in GFP_KERNEL to blkdev_zone_mgmt() and use
memalloc_no{io,fs}_{save,restore}() to define the allocation scope, we can
drop the gfp_mask parameter from blkdev_zone_mgmt() as well as
blkdev_zone_reset_all() and blkdev_zone_reset_all_emulated().
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Mike Snitzer <snitzer@kernel.org>
Link: https://lore.kernel.org/r/20240128-zonefs_nofs-v3-5-ae3b7c8def61@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With the removal of the support for host-aware zoned devices,
blk_revalidate_zone_cb() should never see the zone type
BLK_ZONE_TYPE_SEQWRITE_PREF (sequential write preffered zones). Treat
this zone type as being invalid.
Fixes: 7437bb73f0 ("block: remove support for the host aware zone model")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240107072212.1071080-1-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
disk_clear_zoned is unused now that the last warts of the host-aware
model support in sd are gone.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20231228075141.362560-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A previous commit split disk_set_zoned(..., bool) into not taking an
argument for whether to set or clear, and instead added
disk_clear_zoned() as the counterpart. However, that commit neglected
to export the new symbol, causing failures for modular drivers that
used it.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: d73e93b4df ("block: simplify disk_set_zoned")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
