Pull block fixes from Jens Axboe:

 - ublk selftests for missing coverage

 - two fixes for the block integrity code

 - fix for the newly added newly added PR read keys ioctl, limiting the
   memory that can be allocated

 - work around for a deadlock that can occur with ublk, where partition
   scanning ends up recursing back into file closure, which needs the
   same mutex grabbed. Not the prettiest thing in the world, but an
   acceptable work-around until we can eliminate the reliance on
   disk->open_mutex for this

 - fix for a race between enabling writeback throttling and new IO
   submissions

 - move a bit of bio flag handling code. No changes, but needed for a
   patchset for a future kernel

 - fix for an init time id leak failure in rnbd

 - loop/zloop state check fix

* tag 'block-6.19-20251218' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  block: validate interval_exp integrity limit
  block: validate pi_offset integrity limit
  block: rnbd-clt: Fix leaked ID in init_dev()
  ublk: fix deadlock when reading partition table
  block: add allocation size check in blkdev_pr_read_keys()
  Documentation: admin-guide: blockdev: replace zone_capacity with zone_capacity_mb when creating devices
  zloop: use READ_ONCE() to read lo->lo_state in queue_rq path
  loop: use READ_ONCE() to read lo->lo_state without locking
  block: fix race between wbt_enable_default and IO submission
  selftests: ublk: add user copy test cases
  selftests: ublk: add support for user copy to kublk
  selftests: ublk: forbid multiple data copy modes
  selftests: ublk: don't share backing files between ublk servers
  selftests: ublk: use auto_zc for PER_IO_DAEMON tests in stress_04
  selftests: ublk: fix fio arguments in run_io_and_recover()
  selftests: ublk: remove unused ios map in seq_io.bt
  selftests: ublk: correct last_rw map type in seq_io.bt
  selftests: ublk: fix overflow in ublk_queue_auto_zc_fallback()
  block: move around bio flagging helpers

Various code assumes that the integrity interval is at least 1 sector
and evenly divides the logical block size. Add these checks to
blk_validate_integrity_limits(). This guards against block drivers that
report invalid interval_exp values.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The PI tuple must be contained within the metadata value, so validate
that pi_offset + pi_tuple_size <= metadata_size. This guards against
block drivers that report invalid pi_offset values.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blkdev_pr_read_keys() takes num_keys from userspace and uses it to
calculate the allocation size for keys_info via struct_size(). While
there is a check for SIZE_MAX (integer overflow), there is no upper
bound validation on the allocation size itself.

A malicious or buggy userspace can pass a large num_keys value that
doesn't trigger overflow but still results in an excessive allocation
attempt, causing a warning in the page allocator when the order exceeds
MAX_PAGE_ORDER.

Fix this by introducing PR_KEYS_MAX to limit the number of keys to
a sane value. This makes the SIZE_MAX check redundant, so remove it.
Also switch to kvzalloc/kvfree to handle larger allocations gracefully.

Fixes: 22a1ffea5f80 ("block: add IOC_PR_READ_KEYS ioctl")
Tested-by: syzbot+660d079d90f8a1baf54d@syzkaller.appspotmail.com
Reported-by: syzbot+660d079d90f8a1baf54d@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=660d079d90f8a1baf54d
Link: https://lore.kernel.org/all/20251212013510.3576091-1-kartikey406@gmail.com/T/ [v1]
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

When wbt_enable_default() is moved out of queue freezing in elevator_change(),
it can cause the wbt inflight counter to become negative (-1), leading to hung
tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter
is in an inconsistent state.

The issue occurs because wbt_enable_default() could race with IO submission,
allowing the counter to be decremented before proper initialization. This manifests
as:

  rq_wait[0]:
    inflight:             -1
    has_waiters:        True

rwb_enabled() checks the state, which can be updated exactly between wbt_wait()
(rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter
will become negative.

And results in hung task warnings like:
  task:kworker/u24:39 state:D stack:0 pid:14767
  Call Trace:
    rq_qos_wait+0xb4/0x150
    wbt_wait+0xa9/0x100
    __rq_qos_throttle+0x24/0x40
    blk_mq_submit_bio+0x672/0x7b0
    ...

Fix this by:

1. Splitting wbt_enable_default() into:
   - __wbt_enable_default(): Returns true if wbt_init() should be called
   - wbt_enable_default(): Wrapper for existing callers (no init)
   - wbt_init_enable_default(): New function that checks and inits WBT

2. Using wbt_init_enable_default() in blk_register_queue() to ensure
   proper initialization during queue registration

3. Move wbt_init() out of wbt_enable_default() which is only for enabling
   disabled wbt from bfq and iocost, and wbt_init() isn't needed. Then the
   original lock warning can be avoided.

4. Removing the ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT flag and its handling
   code since it's no longer needed

This ensures WBT is properly initialized before any IO can be submitted,
preventing the counter from going negative.

Cc: Nilay Shroff <nilay@linux.ibm.com>
Cc: Yu Kuai <yukuai@fnnas.com>
Cc: Guangwu Zhang <guazhang@redhat.com>
Fixes: 78c271344b6f ("block: move wbt_enable_default() out of queue freezing from sched ->exit()")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull block fixes from Jens Axboe:

 - Always initialize DMA state, fixing a potentially nasty issue on the
   block side

 - btrfs zoned write fix with cached zone reports

 - Fix corruption issues in bcache with chained bio's, and further make
   it clear that the chained IO handler is simply a marker, it's not
   code meant to be executed

 - Kill old code dealing with synchronous IO polling in the block layer,
   that has been dead for a long time. Only async polling is supported
   these days

 - Fix a lockdep issue in tag_set management, moving it to RCU

 - Fix an issue with ublks bio_vec iteration

 - Don't unconditionally enforce blocking issue of ublk control
   commands, allow some of them with non-blocking issue as they
   do not block

* tag 'block-6.19-20251211' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  blk-mq-dma: always initialize dma state
  blk-mq: delete task running check in blk_hctx_poll()
  block: fix cached zone reports on devices with native zone append
  block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock
  ublk: don't mutate struct bio_vec in iteration
  block: prohibit calls to bio_chain_endio
  bcache: fix improper use of bi_end_io
  ublk: allow non-blocking ctrl cmds in IO_URING_F_NONBLOCK issue

Ensure the dma state is initialized when we're not using the contiguous
iova, otherwise the caller may be using a stale state from a previous
request that could use the coalesed iova allocation.

Fixes: 2f6b2565d43cdb5 ("block: accumulate memory segment gaps per bio")
Reported-by: Sebastian Ott <sebott@redhat.com>
Tested-by: Sebastian Ott <sebott@redhat.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk_hctx_poll() always checks if the task is running or not, and returns
1 if the task is running. This is a leftover from when polled IO was
purely for synchronous IO, and doesn't make sense anymore when polled IO
is purely asynchronous. Similarly, marking the task as TASK_RUNNING is
also superflous, as the very much has to be running to enter the
function in the first place.

It looks like there has been this judgment for historical reasons, and
in very early versions of this function the user would set the process
state to TASK_UNINTERRUPTIBLE.

Signed-off-by: Diangang Li <lidiangang@bytedance.com>
Signed-off-by: Fengnan Chang <changfengnan@bytedance.com>
[axboe: kill all remnants of task running, pointless now. massage message]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

When mounting a btrfs file system on virtio-blk which supports native
Zone Append there has been a WARN triggering in btrfs' space management
code.

Further looking into btrfs' zoned statistics uncovered the filesystem
expecting the zones to be used, but the write pointers being 0:
 # cat /sys/fs/btrfs/8eabd2e7-3294-4f9e-9b58-7e64135c8bf4/zoned_stats
 active block-groups: 4
         reclaimable: 0
         unused: 0
         need reclaim: false
 data relocation block-group: 1342177280
 active zones:
         start: 1073741824, wp: 0 used: 0, reserved: 0, unusable: 0
         start: 1342177280, wp: 0 used: 0, reserved: 0, unusable: 0
         start: 1610612736, wp: 0 used: 16384, reserved: 0, unusable: 18446744073709535232
         start: 1879048192, wp: 0 used: 131072, reserved: 0, unusable: 18446744073709420544

Looking at the blkzone report output for the zone in question
(1610612736) the write pointer on the device moved, but the filesystem
did not see a change on the write pointer:
 # blkzone report -c 1 -o 0x300000 /dev/vda
   start: 0x000300000, len 0x080000, cap 0x080000, wptr 0x000040 reset:0 non-seq:0, zcond: 2(oi) [type: 2(SEQ_WRITE_REQUIRED)]

The zone write pointer is 0, because btrfs is using the cached version
of blkdev_report_zones() and as virtio-blk is supporting native zone
append, but blkdev_revalidate_zones() does not initialize the zone write
plugs in this case.

Not skipping the revalidate of sequential zones in
blkdev_revalidate_zones() callchain fixes this issue.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Fixes: a6aa36e957a1 ("block: Remove zone write plugs when handling native zone append writes")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk_mq_{add,del}_queue_tag_set() functions add and remove queues from
tagset, the functions make sure that tagset and queues are marked as
shared when two or more queues are attached to the same tagset.
Initially a tagset starts as unshared and when the number of added
queues reaches two, blk_mq_add_queue_tag_set() marks it as shared along
with all the queues attached to it. When the number of attached queues
drops to 1 blk_mq_del_queue_tag_set() need to mark both the tagset and
the remaining queues as unshared.

Both functions need to freeze current queues in tagset before setting on
unsetting BLK_MQ_F_TAG_QUEUE_SHARED flag. While doing so, both functions
hold set->tag_list_lock mutex, which makes sense as we do not want
queues to be added or deleted in the process. This used to work fine
until commit 98d81f0df70c ("nvme: use blk_mq_[un]quiesce_tagset")
made the nvme driver quiesce tagset instead of quiscing individual
queues. blk_mq_quiesce_tagset() does the job and quiesce the queues in
set->tag_list while holding set->tag_list_lock also.

This results in deadlock between two threads with these stacktraces:

  __schedule+0x47c/0xbb0
  ? timerqueue_add+0x66/0xb0
  schedule+0x1c/0xa0
  schedule_preempt_disabled+0xa/0x10
  __mutex_lock.constprop.0+0x271/0x600
  blk_mq_quiesce_tagset+0x25/0xc0
  nvme_dev_disable+0x9c/0x250
  nvme_timeout+0x1fc/0x520
  blk_mq_handle_expired+0x5c/0x90
  bt_iter+0x7e/0x90
  blk_mq_queue_tag_busy_iter+0x27e/0x550
  ? __blk_mq_complete_request_remote+0x10/0x10
  ? __blk_mq_complete_request_remote+0x10/0x10
  ? __call_rcu_common.constprop.0+0x1c0/0x210
  blk_mq_timeout_work+0x12d/0x170
  process_one_work+0x12e/0x2d0
  worker_thread+0x288/0x3a0
  ? rescuer_thread+0x480/0x480
  kthread+0xb8/0xe0
  ? kthread_park+0x80/0x80
  ret_from_fork+0x2d/0x50
  ? kthread_park+0x80/0x80
  ret_from_fork_asm+0x11/0x20

  __schedule+0x47c/0xbb0
  ? xas_find+0x161/0x1a0
  schedule+0x1c/0xa0
  blk_mq_freeze_queue_wait+0x3d/0x70
  ? destroy_sched_domains_rcu+0x30/0x30
  blk_mq_update_tag_set_shared+0x44/0x80
  blk_mq_exit_queue+0x141/0x150
  del_gendisk+0x25a/0x2d0
  nvme_ns_remove+0xc9/0x170
  nvme_remove_namespaces+0xc7/0x100
  nvme_remove+0x62/0x150
  pci_device_remove+0x23/0x60
  device_release_driver_internal+0x159/0x200
  unbind_store+0x99/0xa0
  kernfs_fop_write_iter+0x112/0x1e0
  vfs_write+0x2b1/0x3d0
  ksys_write+0x4e/0xb0
  do_syscall_64+0x5b/0x160
  entry_SYSCALL_64_after_hwframe+0x4b/0x53

The top stacktrace is showing nvme_timeout() called to handle nvme
command timeout. timeout handler is trying to disable the controller and
as a first step, it needs to blk_mq_quiesce_tagset() to tell blk-mq not
to call queue callback handlers. The thread is stuck waiting for
set->tag_list_lock as it tries to walk the queues in set->tag_list.

The lock is held by the second thread in the bottom stack which is
waiting for one of queues to be frozen. The queue usage counter will
drop to zero after nvme_timeout() finishes, and this will not happen
because the thread will wait for this mutex forever.

Given that [un]quiescing queue is an operation that does not need to
sleep, update blk_mq_[un]quiesce_tagset() to use RCU instead of taking
set->tag_list_lock, update blk_mq_{add,del}_queue_tag_set() to use RCU
safe list operations. Also, delete INIT_LIST_HEAD(&q->tag_set_list)
in blk_mq_del_queue_tag_set() because we can not re-initialize it while
the list is being traversed under RCU. The deleted queue will not be
added/deleted to/from a tagset and it will be freed in blk_free_queue()
after the end of RCU grace period.

Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Fixes: 98d81f0df70c ("nvme: use blk_mq_[un]quiesce_tagset")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>