Add test_params_01.sh for SET_PARAMS. The test checks valid basic
parameters and several invalid parameter cases.

Also cover zoned parameters, including a non-power-of-2 zone size. This
case must fail in SET_PARAMS instead of being accepted and rejected later
when the device is started.

Signed-off-by: Yao Sang <sangyao@kylinos.cn>
Link: https://patch.msgid.link/20260814023226.354288-4-sangyao@kylinos.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The normal kublk add command goes through device startup. It does not
tell the shell test whether a bad parameter is rejected by SET_PARAMS or
later by START_DEV.

Add a set_params command. It creates a temporary ublk device, sends
SET_PARAMS with the command line parameters, returns the ioctl result,
and deletes the device before START_DEV.

Signed-off-by: Yao Sang <sangyao@kylinos.cn>
Link: https://patch.msgid.link/20260814023226.354288-3-sangyao@kylinos.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Batch AUTO_BUF_REG COMMIT must unregister the old auto_buf index before
storing the next one. Fixed per-tag indexing (A == B) masks bugs that
clear after overwriting io->buf.

Add kublk --rotate_auto_buf so each tag alternates between two sparse
buffer indices, and test_batch_04.sh to exercise that path. Without the
driver fix, the request ref stays stuck and I/O hangs; the test uses a
short timeout and kills the ublk daemon to recover. With the fix, a
small write completes quickly.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20260730024050.1062354-1-yangxiuwei@kylinos.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add test loop_08, which creates a ublk device with UBLK_F_IO_DESC_SIZE
enabled and io_desc_size set to 64. The test issues verified I/O to the
device using fio.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://patch.msgid.link/20260803211441.2538144-8-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add an optional --io_desc_size argument to the kublk add/recover
commands to enable UBLK_F_IO_DESC on the ublk device. The mmap()
arguments and ublk_get_iod() computation are adjusted accordingly.

Display the configured io_desc_size in the kublk list output for ublk
devices with UBLK_F_IO_DESC.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://patch.msgid.link/20260803211441.2538144-7-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

ublk passes the parameters of incoming I/O in memory shared between the
kernel ublk driver and userspace ublk server in struct ublksrv_io_desc.
The size of this struct is currently fixed to 24 bytes, which has been
an obstacle to extending it with additional fields [1]. Additionally,
with multiple ublk server threads handling I/Os from the same ublk queue
(possible with UBLK_F_PER_IO_DAEMON or UBLK_F_BATCH_IO), false sharing
results from adjacent io_descs sharing the same cache line.

Add a ublk feature UBLK_F_IO_DESC_SIZE to allow a ublk server to
override the size of each io_desc. The size must be at least 24 and a
multiple of 8 to store a properly-aligned struct ublksrv_io_desc. It's
also limited to a maximum of 256, though this bound could be lifted in
the future.

The struct ublksrv_io_desc is located at the beginning of each io_desc
and the remainder is padding. The mmap() performed for each queue must
have a length of queue_depth * io_desc_size rounded up to the page size.
The mmap() offset must be q_id * UBLK_MAX_QUEUE_DEPTH * io_desc_size,
also rounded up to the page size.

[1]: https://lore.kernel.org/linux-block/aV8QfvaNO5P6vOs6@fedora/

Suggested-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://patch.msgid.link/20260803211441.2538144-6-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

dev->nthreads is derived from the user-requested queue count before the
ADD command, but the kernel may reduce nr_hw_queues (capped to
nr_cpu_ids). When the VM has fewer CPUs than requested queues, the
daemon creates more handler threads than there are kernel queues.

In non-batch mode, the extra threads access uninitialized queues
(q_depth=0), submit zero io_uring SQEs, and block forever in
io_cqring_wait. In batch mode, the extra threads cause similar hangs
during device removal.

In both cases, the stuck threads prevent the daemon from closing the
char device, holding the last ublk_device reference and causing
ublk_ctrl_del_dev() to hang in wait_event_interruptible().

Fix by capping dev->nthreads to the kernel-returned nr_hw_queues after
the ADD command completes. per_io_tasks mode is excluded because threads
interleave across all queues, so nthreads > nr_hw_queues is valid.

Fixes: abe54c160346 ("selftests: ublk: kublk: decouple ublk_queues from ublk server threads")
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20260513101941.1373998-1-tom.leiming@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The end-to-end integrity ublk selftest test_integrity_02 requires a
relatively recent fio version to support I/O with integrity buffers. Add
a version test_integrity_03 that uses the block layer's auto integrity
path instead. The auto integrity code doesn't check the application tag,
and doesn't indicate the bad guard/ref tag (just returns EILSEQ). But
it's a good smoke-test of the ublk integrity code and provides coverage
of the auto integrity path as well.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20260421200901.1528842-4-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fio 3.42 was released with the needed fix for test_integrity_02.sh.
Allow 3.42 and newer in the fio version check.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20260421200901.1528842-3-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The _cleanup helper function doesn't take any arguments, so drop them
from its callers.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20260421200901.1528842-2-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>