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* null_blk: Don't bother validating blocksizeJohn Garry2024-07-091-3/+0
| | | | | | | | | | | | | The block queue limits validation does this for us now. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: John Garry <john.g.garry@oracle.com> Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Acked-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Link: https://lore.kernel.org/r/20240708091651.177447-4-john.g.garry@oracle.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: Remove REQ_OP_ZONE_RESET_ALL emulationDamien Le Moal2024-07-051-1/+1
| | | | | | | | | | | | | | | 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>
* null_blk: Introduce the zone_full parameterDamien Le Moal2024-07-053-3/+17
| | | | | | | | | | | | | | | Allow creating a zoned null_blk device with the initial state of its sequential write required zones to be FULL. This is convenient to avoid having to first write these zones to perform read performance evaluation or test zone management operations such as zone reset (and zone reset all). 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/20240704052816.623865-2-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: don't initialize static 'g_virt_boundary' to falseZhu Yanjun2024-07-041-1/+1
| | | | | | | | No functional changes intended. Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev> Link: https://lore.kernel.org/r/20240704010638.324349-1-yanjun.zhu@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: Fix description of the fua parameterDamien Le Moal2024-07-021-1/+1
| | | | | | | | | | | | | | | The description of the fua module parameter is defined using MODULE_PARM_DESC() with the first argument passed being "zoned". That is the wrong name, obviously. Fix that by using the correct "fua" parameter name so that "modinfo null_blk" displays correct information. Fixes: f4f84586c8b9 ("null_blk: Introduce fua attribute") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Link: https://lore.kernel.org/r/20240702073234.206458-1-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: Do not set disk->nr_zonesDamien Le Moal2024-06-211-2/+0
| | | | | | | | | | | | In null_register_zoned_dev(), there is no need to set disk->nr_zones as the now uncoditional call to blk_revalidate_disk_zones() will do that. So remove the assignment using bdev_nr_zones(). 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/20240621031506.759397-2-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: move the zone_resetall flag to queue_limitsChristoph Hellwig2024-06-191-2/+1
| | | | | | | | | | | Move the zone_resetall flag into the queue_limits feature field so that it can be set atomically with the queue frozen. 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/20240617060532.127975-24-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: move the zoned flag into the features fieldChristoph Hellwig2024-06-191-1/+1
| | | | | | | | | | | Move the zoned flags 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/20240617060532.127975-23-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: move the nonrot flag to queue_limitsChristoph Hellwig2024-06-191-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | Move the nonrot flag into the queue_limits feature field so that it can be set atomically with the queue frozen. Use the chance to switch to defaulting to non-rotational and require the driver to opt into rotational, which matches the polarity of the sysfs interface. For the z2ram, ps3vram, 2x memstick, ubiblock and dcssblk the new rotational flag is not set as they clearly are not rotational despite this being a behavior change. There are some other drivers that unconditionally set the rotational flag to keep the existing behavior as they arguably can be used on rotational devices even if that is probably not their main use today (e.g. virtio_blk and drbd). The flag is automatically inherited in blk_stack_limits matching the existing behavior in dm and md. 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/20240617060532.127975-15-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: move cache control settings out of queue->flagsChristoph Hellwig2024-06-191-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move the cache control settings into the queue_limits so that the flags can be set atomically with the device queue frozen. Add new features and flags field for the driver set flags, and internal (usually sysfs-controlled) flags in the block layer. Note that we'll eventually remove enough field from queue_limits to bring it back to the previous size. The disable flag is inverted compared to the previous meaning, which means it now survives a rescan, similar to the max_sectors and max_discard_sectors user limits. The FLUSH and FUA flags are now inherited by blk_stack_limits, which simplified the code in dm a lot, but also causes a slight behavior change in that dm-switch and dm-unstripe now advertise a write cache despite setting num_flush_bios to 0. The I/O path will handle this gracefully, but as far as I can tell the lack of num_flush_bios and thus flush support is a pre-existing data integrity bug in those targets that really needs fixing, after which a non-zero num_flush_bios should be required in dm for targets that map to underlying devices. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/20240617060532.127975-14-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: fix validation of block sizeAndreas Hindborg2024-06-051-2/+2
| | | | | | | | | | | | | | | | Block size should be between 512 and PAGE_SIZE and be a power of 2. The current check does not validate this, so update the check. Without this patch, null_blk would Oops due to a null pointer deref when loaded with bs=1536 [1]. Link: https://lore.kernel.org/all/87wmn8mocd.fsf@metaspace.dk/ Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20240603192645.977968-1-nmi@metaspace.dk [axboe: remove unnecessary braces and != 0 check] Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: Do not allow runt zone with zone capacity smaller then zone sizeDamien Le Moal2024-05-301-0/+11
| | | | | | | | | | | | | | | | | | | A zoned device with a smaller last zone together with a zone capacity smaller than the zone size does make any sense as that does not correspond to any possible setup for a real device: 1) For ZNS and zoned UFS devices, all zones are always the same size. 2) For SMR HDDs, all zones always have the same capacity. In other words, if we have a smaller last runt zone, then this zone capacity should always be equal to the zone size. Add a check in null_init_zoned_dev() to prevent a configuration to have both a smaller zone size and a zone capacity smaller than the zone size. Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Niklas Cassel <cassel@kernel.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20240530054035.491497-2-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: Print correct max open zones limit in null_init_zoned_dev()Damien Le Moal2024-05-281-1/+1
| | | | | | | | | | | | When changing the maximum number of open zones, print that number instead of the total number of zones. Fixes: dc4d137ee3b7 ("null_blk: add support for max open/active zone limit for zoned devices") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Niklas Cassel <cassel@kernel.org> Link: https://lore.kernel.org/r/20240528062852.437599-1-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: Fix return value of nullb_device_power_store()Damien Le Moal2024-05-271-0/+1
| | | | | | | | | | | | | | | When powering on a null_blk device that is not already on, the return value ret that is initialized to be count is reused to check the return value of null_add_dev(), leading to nullb_device_power_store() to return null_add_dev() return value (0 on success) instead of "count". So make sure to set ret to be equal to count when there are no errors. Fixes: a2db328b0839 ("null_blk: fix null-ptr-dereference while configuring 'power' and 'submit_queues'") Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Kanchan Joshi <joshi.k@samsung.com> Link: https://lore.kernel.org/r/20240527043445.235267-1-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: fix null-ptr-dereference while configuring 'power' and 'submit_queues'Yu Kuai2024-05-231-14/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Writing 'power' and 'submit_queues' concurrently will trigger kernel panic: Test script: modprobe null_blk nr_devices=0 mkdir -p /sys/kernel/config/nullb/nullb0 while true; do echo 1 > submit_queues; echo 4 > submit_queues; done & while true; do echo 1 > power; echo 0 > power; done Test result: BUG: kernel NULL pointer dereference, address: 0000000000000148 Oops: 0000 [#1] PREEMPT SMP RIP: 0010:__lock_acquire+0x41d/0x28f0 Call Trace: <TASK> lock_acquire+0x121/0x450 down_write+0x5f/0x1d0 simple_recursive_removal+0x12f/0x5c0 blk_mq_debugfs_unregister_hctxs+0x7c/0x100 blk_mq_update_nr_hw_queues+0x4a3/0x720 nullb_update_nr_hw_queues+0x71/0xf0 [null_blk] nullb_device_submit_queues_store+0x79/0xf0 [null_blk] configfs_write_iter+0x119/0x1e0 vfs_write+0x326/0x730 ksys_write+0x74/0x150 This is because del_gendisk() can concurrent with blk_mq_update_nr_hw_queues(): nullb_device_power_store nullb_apply_submit_queues null_del_dev del_gendisk nullb_update_nr_hw_queues if (!dev->nullb) // still set while gendisk is deleted return 0 blk_mq_update_nr_hw_queues dev->nullb = NULL Fix this problem by resuing the global mutex to protect nullb_device_power_store() and nullb_update_nr_hw_queues() from configfs. Fixes: 45919fbfe1c4 ("null_blk: Enable modifying 'submit_queues' after an instance has been configured") Reported-and-tested-by: Yi Zhang <yi.zhang@redhat.com> Closes: https://lore.kernel.org/all/CAHj4cs9LgsHLnjg8z06LQ3Pr5cax-+Ps+xT7AP7TPnEjStuwZA@mail.gmail.com/ Signed-off-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev> Link: https://lore.kernel.org/r/20240523153934.1937851-1-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: Fix two sparse warningsBart Van Assche2024-05-142-2/+7
| | | | | | | | | | | | | | | | | Fix the following sparse warnings: drivers/block/null_blk/main.c:1243:35: warning: incorrect type in return expression (different base types) drivers/block/null_blk/main.c:1243:35: expected int drivers/block/null_blk/main.c:1243:35: got restricted blk_status_t drivers/block/null_blk/main.c:1291:30: warning: incorrect type in return expression (different base types) drivers/block/null_blk/main.c:1291:30: expected restricted blk_status_t drivers/block/null_blk/main.c:1291:30: got int Cc: Christoph Hellwig <hch@lst.de> Cc: Damien Le Moal <dlemoal@kernel.org> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20240510201816.24921-1-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Merge tag 'for-6.10/block-20240511' of git://git.kernel.dk/linuxLinus Torvalds2024-05-133-178/+225
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull block updates from Jens Axboe: - Add a partscan attribute in sysfs, fixing an issue with systemd relying on an internal interface that went away. - Attempt #2 at making long running discards interruptible. The previous attempt went into 6.9, but we ended up mostly reverting it as it had issues. - Remove old ida_simple API in bcache - Support for zoned write plugging, greatly improving the performance on zoned devices. - Remove the old throttle low interface, which has been experimental since 2017 and never made it beyond that and isn't being used. - Remove page->index debugging checks in brd, as it hasn't caught anything and prepares us for removing in struct page. - MD pull request from Song - Don't schedule block workers on isolated CPUs * tag 'for-6.10/block-20240511' of git://git.kernel.dk/linux: (84 commits) blk-throttle: delay initialization until configuration blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW block: fix that util can be greater than 100% block: support to account io_ticks precisely block: add plug while submitting IO bcache: fix variable length array abuse in btree_iter bcache: Remove usage of the deprecated ida_simple_xx() API md: Revert "md: Fix overflow in is_mddev_idle" blk-lib: check for kill signal in ioctl BLKDISCARD block: add a bio_await_chain helper block: add a blk_alloc_discard_bio helper block: add a bio_chain_and_submit helper block: move discard checks into the ioctl handler block: remove the discard_granularity check in __blkdev_issue_discard block/ioctl: prefer different overflow check null_blk: Fix the WARNING: modpost: missing MODULE_DESCRIPTION() block: fix and simplify blkdevparts= cmdline parsing block: refine the EOF check in blkdev_iomap_begin block: add a partscan sysfs attribute for disks block: add a disk_has_partscan helper ...
| * null_blk: Fix the WARNING: modpost: missing MODULE_DESCRIPTION()Zhu Yanjun2024-05-061-0/+1
| | | | | | | | | | | | | | | | | | | | No functional changes intended. Fixes: f2298c0403b0 ("null_blk: multi queue aware block test driver") Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Link: https://lore.kernel.org/r/20240506075538.6064-1-yanjun.zhu@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * null_blk: Fix missing mutex_destroy() at module removalZhu Yanjun2024-04-251-0/+2
| | | | | | | | | | | | | | | | | | | | When a mutex lock is not used any more, the function mutex_destroy should be called to mark the mutex lock uninitialized. Fixes: f2298c0403b0 ("null_blk: multi queue aware block test driver") Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev> Link: https://lore.kernel.org/r/20240425171635.4227-1-yanjun.zhu@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * null_blk: Simplify null_zone_write()Damien Le Moal2024-04-171-20/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In null_zone_write, we do not need to first check if the target zone condition is FULL, READONLY or OFFLINE: for theses conditions, the check of the command sector against the zone write pointer will always result in the command failing. Remove these checks. We still however need to check that the target zone write pointer is not invalid for zone append operations. To do so, add the macro NULL_ZONE_INVALID_WP and use it in null_set_zone_cond() when changing a zone to READONLY or OFFLINE condition. Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20240411085502.728558-4-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * null_blk: Do zone resource management only if necessaryDamien Le Moal2024-04-171-146/+165
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For zoned null_blk devices setup without any limit on the maximum number of open and active zones, there is no need to count the number of zones that are implicitly open, explicitly open and closed. This is indicated by the boolean field need_zone_res_mgmt of sturct nullb_device. Modify the zone management functions null_reset_zone(), null_finish_zone(), null_open_zone() and null_close_zone() to manage the zone condition counters only if the device need_zone_res_mgmt field is true. With this change, the function __null_close_zone() is removed and integrated into the 2 caller sites directly, with the null_close_imp_open_zone() call site greatly simplified as this function closes zones that are known to be in the implicit open condition. null_zone_write() is modified in a similar manner to do zone condition accouting only when the device need_zone_res_mgmt field is true. With these changes, the inline helpers null_lock_zone_res() and null_unlock_zone_res() are removed and replaced with direct calls to spin_lock()/spin_unlock(). Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20240411085502.728558-3-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * null_blk: Have all null_handle_xxx() return a blk_status_tDamien Le Moal2024-04-171-10/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | Modify the null_handle_flush() and null_handle_rq() functions to return a blk_status_t instead of an errno to simplify the call sites of these functions and to be consistant with other null_handle_xxx() functions. Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20240411085502.728558-2-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * block: Simplify blk_revalidate_disk_zones() interfaceDamien Le Moal2024-04-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * null_blk: Introduce fua attributeDamien Le Moal2024-04-172-2/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add the fua configfs attribute and module parameter to allow configuring if the device supports FUA or not. Using this attribute has an effect on the null_blk device only if memory backing is enabled together with a write cache (cache_size option). This new attribute allows configuring a null_blk device with a write cache but without FUA support. This is convenient to test the block layer flush machinery. 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> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> 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/20240408014128.205141-18-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * null_blk: Introduce zone_append_max_sectors attributeDamien Le Moal2024-04-173-4/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add the zone_append_max_sectors configfs attribute and module parameter to allow configuring the maximum number of 512B sectors of zone append operations. This attribute is meaningful only for zoned null block devices. If not specified, the default is unchanged and the zoned device max append sectors limit is set to the device max sectors limit. If a non 0 value is used for this attribute, which is the default, then native support for zone append operations is enabled. Setting a 0 value disables native zone append operations support to instead use the block layer emulation. 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: Chaitanya Kulkarni <kch@nvidia.com> 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/20240408014128.205141-17-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
| * null_blk: Do not request ELEVATOR_F_ZBD_SEQ_WRITE elevator featureDamien Le Moal2024-04-171-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With zone write plugging enabled at the block layer level, a zoned device can only ever see at most a single write operation per zone. There is thus no need to request a block scheduler with strick per-zone sequential write ordering control through the ELEVATOR_F_ZBD_SEQ_WRITE feature. Removing this allows using a zoned null_blk device with any scheduler, including "none". 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> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> 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/20240408014128.205141-16-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* | nullblk: Fix cleanup order in null_add_dev() error pathDamien Le Moal2024-04-021-2/+2
|/ | | | | | | | | | | | | | In null_add_dev(), if an error happen after initializing the resources for a zoned null block device, we must free these resources before exiting the function. To ensure this, move the out_cleanup_zone label after out_cleanup_disk as we jump to this latter label if an error happens after calling null_init_zoned_dev(). Fixes: e440626b1caf ("null_blk: pass queue_limits to blk_mq_alloc_disk") Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20240330005300.1503252-1-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: Delete nullb.{queue_depth, nr_queues}John Garry2024-02-222-13/+0
| | | | | | | | | | | | Since commit 8b631f9cf0b8 ("null_blk: remove the bio based I/O path"), struct nullb members queue_depth and nr_queues are only ever written, so delete them. With that, null_exit_hctx() can also be deleted. Signed-off-by: John Garry <john.g.garry@oracle.com> Link: https://lore.kernel.org/r/20240222083420.6026-1-john.g.garry@oracle.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: pass queue_limits to blk_mq_alloc_diskChristoph Hellwig2024-02-203-31/+29
| | | | | | | | | | | | | Pass the queue limits directly to blk_mq_alloc_disk instead of setting them one at a time. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Tested-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20240220093248.3290292-6-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: remove null_gendisk_registerChristoph Hellwig2024-02-201-25/+16
| | | | | | | | | | | | | | null_gendisk_register isn't a very useful abstraction given that it doesn't even allocate the gendisk. Merge it into the only caller instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Tested-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20240220093248.3290292-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: refactor tag_set setupChristoph Hellwig2024-02-201-55/+51
| | | | | | | | | | | | | | Move the tagset initialization out of null_add_dev into a new null_setup_tagset helper, and move the shared vs local differences out of null_init_tag_set into the callers. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Tested-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20240220093248.3290292-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: initialize the tag_set timeout in null_init_tag_setChristoph Hellwig2024-02-201-1/+1
| | | | | | | | | | | | | Otherwise it will be reset to the always same value when initializing a device using the shared tag_set. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Tested-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20240220093248.3290292-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: remove the bio based I/O pathChristoph Hellwig2024-02-204-328/+69
| | | | | | | | | | | | | | | | | | | | | | | | | The bio based I/O path complicates null_blk and also make various data structures, including the per-command one way bigger than required for the main request based interface. As the bio-based path is mostly used by stacking drivers and simple memory based drivers, and brd is a good example driver for the latter there is no need to have a bio based path in null_blk. Remove the path to simplify the driver and make future block layer API changes simpler by not having to deal with the complex two API setup in null_blk. Note that the queue_mode field in struct nullb_device is kept as that is simpler than having two different places to check the value and fully open coding the debugfs helpers as the existing ones won't work without a named struct member. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Tested-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20240220093248.3290292-2-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: pass a queue_limits argument to blk_alloc_diskChristoph Hellwig2024-02-201-3/+4
| | | | | | | | | | | | | | | Pass a queue_limits to blk_alloc_disk and apply it if non-NULL. This will allow allocating queues with valid queue limits instead of setting the values one at a time later. Also change blk_alloc_disk to return an ERR_PTR instead of just NULL which can't distinguish errors. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com> Link: https://lore.kernel.org/r/20240215071055.2201424-2-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: pass a queue_limits argument to blk_mq_alloc_diskChristoph Hellwig2024-02-131-1/+1
| | | | | | | | | | | | | | | | | Pass a queue_limits to blk_mq_alloc_disk and apply it if non-NULL. 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: Keith Busch <kbusch@kernel.org> Reviewed-by: John Garry <john.g.garry@oracle.com> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/20240213073425.1621680-11-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: add configfs variable shared_tagsShin'ichiro Kawasaki2024-02-082-18/+21
| | | | | | | | | | | | | | | | | | Allow setting shared_tags through configfs, which could only be set as a module parameter. For that purpose, delay tag_set initialization from null_init() to null_add_dev(). Refer tag_set.ops as the flag to check if tag_set is initialized or not. The following parameters can not be set through configfs yet: timeout requeue init_hctx Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Link: https://lore.kernel.org/r/20240130042134.2463659-1-shinichiro.kawasaki@wdc.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: Remove usage of the deprecated ida_simple_xx() APIChristophe JAILLET2024-01-141-2/+2
| | | | | | | | | | | ida_alloc() and ida_free() should be preferred to the deprecated ida_simple_get() and ida_simple_remove(). This is less verbose. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Link: https://lore.kernel.org/r/bf257b1078475a415cdc3344c6a750842946e367.1705222845.git.christophe.jaillet@wanadoo.fr Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: use the default discard granularityChristoph Hellwig2023-12-291-1/+0
| | | | | | | | | The discard granularity now defaults to a single sector, so don't set that value explicitly. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20231228075545.362768-7-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: don't cap max_hw_sectors to BLK_DEF_MAX_SECTORSChristoph Hellwig2023-12-271-10/+2
| | | | | | | | | | | | | | | null_blk has some rather odd capping of the max_hw_sectors value to BLK_DEF_MAX_SECTORS, which doesn't make sense - max_hw_sector is the hardware limit, and BLK_DEF_MAX_SECTORS despite the confusing name is the default cap for the max_sectors field used for normal file system I/O. Remove all the capping, and simply leave it to the block layer or user to take up or not all of that for file system I/O. Fixes: ea17fd354ca8 ("null_blk: Allow controlling max_hw_sectors limit") Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20231227092305.279567-2-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: simplify disk_set_zonedChristoph Hellwig2023-12-201-1/+1
| | | | | | | | | | | | | 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>
* block: remove support for the host aware zone modelChristoph Hellwig2023-12-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | When zones were first added the SCSI and ATA specs, two different models were supported (in addition to the drive managed one that is invisible to the host): - host managed where non-conventional zones there is strict requirement to write at the write pointer, or else an error is returned - host aware where a write point is maintained if writes always happen at it, otherwise it is left in an under-defined state and the sequential write preferred zones behave like conventional zones (probably very badly performing ones, though) Not surprisingly this lukewarm model didn't prove to be very useful and was finally removed from the ZBC and SBC specs (NVMe never implemented it). Due to to the easily disappearing write pointer host software could never rely on the write pointer to actually be useful for say recovery. Fortunately only a few HDD prototypes shipped using this model which never made it to mass production. Drop the support before it is too late. Note that any such host aware prototype HDD can still be used with Linux as we'll now treat it as a conventional HDD. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Link: https://lore.kernel.org/r/20231217165359.604246-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block/null_blk: Fix double blk_mq_start_request() warningChengming Zhou2023-11-201-12/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | When CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION is enabled, null_queue_rq() would return BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE for the request, which has been marked as MQ_RQ_IN_FLIGHT by blk_mq_start_request(). Then null_queue_rqs() put these requests in the rqlist, return back to the block layer core, which would try to queue them individually again, so the warning in blk_mq_start_request() triggered. Fix it by splitting the null_queue_rq() into two parts: the first is the preparation of request, the second is the handling of request. We put the blk_mq_start_request() after the preparation part, which may fail and return back to the block layer core. The throttling also belongs to the preparation part, so move it before blk_mq_start_request(). And change the return type of null_handle_cmd() to void, since it always return BLK_STS_OK now. Reported-by: <syzbot+fcc47ba2476570cbbeb0@syzkaller.appspotmail.com> Closes: https://lore.kernel.org/all/0000000000000e6aac06098aee0c@google.com/ Fixes: d78bfa1346ab ("block/null_blk: add queue_rqs() support") Suggested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Link: https://lore.kernel.org/r/20231120032521.1012037-1-chengming.zhou@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: replace strncpy with strscpyJustin Stitt2023-10-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | `strncpy` is deprecated for use on NUL-terminated destination strings [1]. We should favor a more robust and less ambiguous interface. We expect that both `nullb->disk_name` and `disk->disk_name` be NUL-terminated: | snprintf(nullb->disk_name, sizeof(nullb->disk_name), | "%s", config_item_name(&dev->group.cg_item)); ... | pr_info("disk %s created\n", nullb->disk_name); It seems like NUL-padding may be required due to __assign_disk_name() utilizing a memcpy as opposed to a `str*cpy` api. | static inline void __assign_disk_name(char *name, struct gendisk *disk) | { | if (disk) | memcpy(name, disk->disk_name, DISK_NAME_LEN); | else | memset(name, 0, DISK_NAME_LEN); | } Then we go and print it with `__print_disk_name` which wraps `nullb_trace_disk_name()`. | #define __print_disk_name(name) nullb_trace_disk_name(p, name) This function obviously expects a NUL-terminated string. | const char *nullb_trace_disk_name(struct trace_seq *p, char *name) | { | const char *ret = trace_seq_buffer_ptr(p); | | if (name && *name) | trace_seq_printf(p, "disk=%s, ", name); | trace_seq_putc(p, 0); | | return ret; | } >From the above, we need both 1) a NUL-terminated string and 2) a NUL-padded string. So, let's use strscpy_pad() as per Kees' suggestion from v1. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Cc: Kees Cook <keescook@chromium.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Justin Stitt <justinstitt@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20230919-strncpy-drivers-block-null_blk-main-c-v3-1-10cf0a87a2c3@google.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block/null_blk: add queue_rqs() supportChengming Zhou2023-09-221-0/+20
| | | | | | | | | | | | | | | | Add batched mq_ops.queue_rqs() support in null_blk for testing. The implementation is much easy since null_blk doesn't have commit_rqs(). We simply handle each request one by one, if errors are encountered, leave them in the passed in list and return back. There is about 3.6% improvement in IOPS of fio/t/io_uring on null_blk with hw_queue_depth=256 on my test VM, from 1.09M to 1.13M. Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20230913151616.3164338-6-chengming.zhou@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
* null_blk: fix poll request timeout handlingChengming Zhou2023-09-011-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When doing io_uring benchmark on /dev/nullb0, it's easy to crash the kernel if poll requests timeout triggered, as reported by David. [1] BUG: kernel NULL pointer dereference, address: 0000000000000008 Workqueue: kblockd blk_mq_timeout_work RIP: 0010:null_timeout_rq+0x4e/0x91 Call Trace: ? null_timeout_rq+0x4e/0x91 blk_mq_handle_expired+0x31/0x4b bt_iter+0x68/0x84 ? bt_tags_iter+0x81/0x81 __sbitmap_for_each_set.constprop.0+0xb0/0xf2 ? __blk_mq_complete_request_remote+0xf/0xf bt_for_each+0x46/0x64 ? __blk_mq_complete_request_remote+0xf/0xf ? percpu_ref_get_many+0xc/0x2a blk_mq_queue_tag_busy_iter+0x14d/0x18e blk_mq_timeout_work+0x95/0x127 process_one_work+0x185/0x263 worker_thread+0x1b5/0x227 This is indeed a race problem between null_timeout_rq() and null_poll(). null_poll() null_timeout_rq() spin_lock(&nq->poll_lock) list_splice_init(&nq->poll_list, &list) spin_unlock(&nq->poll_lock) while (!list_empty(&list)) req = list_first_entry() list_del_init() ... blk_mq_add_to_batch() // req->rq_next = NULL spin_lock(&nq->poll_lock) // rq->queuelist->next == NULL list_del_init(&rq->queuelist) spin_unlock(&nq->poll_lock) Fix these problems by setting requests state to MQ_RQ_COMPLETE under nq->poll_lock protection, in which null_timeout_rq() can safely detect this race and early return. Note this patch just fix the kernel panic when request timeout happen. [1] https://lore.kernel.org/all/3893581.1691785261@warthog.procyon.org.uk/ Fixes: 0a593fbbc245 ("null_blk: poll queue support") Reported-by: David Howells <dhowells@redhat.com> Tested-by: David Howells <dhowells@redhat.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Link: https://lore.kernel.org/r/20230901120306.170520-2-chengming.zhou@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Merge branch '6.5/scsi-staging' into 6.5/scsi-fixesMartin K. Petersen2023-07-111-11/+5
|\ | | | | | | | | | | Pull in the currently staged SCSI fixes for 6.5. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
| * scsi: block: nullblk: Set zone limits before revalidating zonesDamien Le Moal2023-07-061-11/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In null_register_zoned_dev(), execute blk_queue_chunk_sectors() and blk_queue_max_zone_append_sectors() to respectively set the zoned device zone size and maximum zone append sector limit before executing blk_revalidate_disk_zones(). This is to allow the block layer zone reavlidation to check these device characteristics prior to checking all zones of the device. Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230703024812.76778-4-dlemoal@kernel.org Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
* | null_blk: Fix: memory release when memory_backed=1Nitesh Shetty2023-06-061-0/+1
|/ | | | | | | | | | | | | | | | | | | | | | Memory/pages are not freed, when unloading nullblk driver. Steps to reproduce issue 1.free -h total used free shared buff/cache available Mem: 7.8Gi 260Mi 7.1Gi 3.0Mi 395Mi 7.3Gi Swap: 0B 0B 0B 2.modprobe null_blk memory_backed=1 3.dd if=/dev/urandom of=/dev/nullb0 oflag=direct bs=1M count=1000 4.modprobe -r null_blk 5.free -h total used free shared buff/cache available Mem: 7.8Gi 1.2Gi 6.1Gi 3.0Mi 398Mi 6.3Gi Swap: 0B 0B 0B Signed-off-by: Anuj Gupta <anuj20.g@samsung.com> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com> Link: https://lore.kernel.org/r/20230605062354.24785-1-nj.shetty@samsung.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Merge tag 'for-6.4/block-2023-05-06' of git://git.kernel.dk/linuxLinus Torvalds2023-05-061-1/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull more block updates from Jens Axboe: - MD pull request via Song: - Improve raid5 sequential IO performance on spinning disks, which fixes a regression since v6.0 (Jan Kara) - Fix bitmap offset types, which fixes an issue introduced in this merge window (Jonathan Derrick) - Cleanup of hweight type used for cgroup writeback (Maxim) - Fix a regression with the "has_submit_bio" changes across partitions (Ming) - Cleanup of QUEUE_FLAG_ADD_RANDOM clearing. We used to set this flag on queues non blk-mq queues, and hence some drivers clear it unconditionally. Since all of these have since been converted to true blk-mq drivers, drop the useless clear as the bit is not set (Chaitanya) - Fix the flags being set in a bio for a flush for drbd (Christoph) - Cleanup and deduplication of the code handling setting block device capacity (Damien) - Fix for ublk handling IO timeouts (Ming) - Fix for a regression in blk-cgroup teardown (Tao) - NBD documentation and code fixes (Eric) - Convert blk-integrity to using device_attributes rather than a second kobject to manage lifetimes (Thomas) * tag 'for-6.4/block-2023-05-06' of git://git.kernel.dk/linux: ublk: add timeout handler drbd: correctly submit flush bio on barrier mailmap: add mailmap entries for Jens Axboe block: Skip destroyed blkg when restart in blkg_destroy_all() writeback: fix call of incorrect macro md: Fix bitmap offset type in sb writer md/raid5: Improve performance for sequential IO docs nbd: userspace NBD now favors github over sourceforge block nbd: use req.cookie instead of req.handle uapi nbd: add cookie alias to handle uapi nbd: improve doc links to userspace spec blk-integrity: register sysfs attributes on struct device blk-integrity: convert to struct device_attribute blk-integrity: use sysfs_emit block/drivers: remove dead clear of random flag block: sync part's ->bd_has_submit_bio with disk's block: Cleanup set_capacity()/bdev_set_nr_sectors()
| * block/drivers: remove dead clear of random flagChaitanya Kulkarni2023-04-251-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | QUEUE_FLAG_ADD_RANDOM is not set before we clear it for "null_blk", "brd", "nbd", "zram", and "bcache" since by default we don't set "QUEUE_FLAG_ADD_RANDOM" to MQ ops. Remove dead clear of QUEUE_FLAG_ADD_RANDOM in above listed drivers. Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> #zram Link: https://lore.kernel.org/r/20230424234628.45544-2-kch@nvidia.com Signed-off-by: Jens Axboe <axboe@kernel.dk>