The ublk selftests mock ublk server kublk supports every data copy mode
except user copy. Add support for user copy to kublk, enabled via the
--user_copy (-u) command line argument. On writes, issue pread() calls
to copy the write data into the ublk_io's buffer before dispatching the
write to the target implementation. On reads, issue pwrite() calls to
copy read data from the ublk_io's buffer before committing the request.
Copy in 2 KB chunks to provide some coverage of the offseting logic.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The functions ublk_queue_use_zc(), ublk_queue_use_auto_zc(), and
ublk_queue_auto_zc_fallback() were returning int, but performing
bitwise AND on q->flags which is __u64.
When a flag bit is set in the upper 32 bits (beyond INT_MAX), the
result of the bitwise AND operation could overflow when cast to int,
leading to incorrect boolean evaluation.
For example, if UBLKS_Q_AUTO_BUF_REG_FALLBACK is 0x8000000000000000:
- (u64)flags & 0x8000000000000000 = 0x8000000000000000
- Cast to int: undefined behavior / incorrect value
- Used in if(): may evaluate incorrectly
Fix by:
1. Changing return type from int to bool for semantic correctness
2. Using !! to explicitly convert to boolean (0 or 1)
This ensures the functions return proper boolean values regardless
of which bit position the flags occupy in the 64-bit field.
Fixes: c3a6d48f86 ("selftests: ublk: remove ublk queue self-defined flags")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Refactor ublk_thread to be a thread-local variable instead of storing
it in ublk_dev:
- Remove pthread_t thread field from struct ublk_thread and move it to
struct ublk_thread_info
- Remove struct ublk_thread array from struct ublk_dev, reducing memory
footprint
- Define struct ublk_thread as local variable in __ublk_io_handler_fn()
instead of accessing it from dev->threads[]
- Extract main IO handling logic into __ublk_io_handler_fn() which is
marked as noinline
- Move CPU affinity setup to ublk_io_handler_fn() before calling
__ublk_io_handler_fn()
- Update ublk_thread_set_sched_affinity() to take struct ublk_thread_info *
instead of struct ublk_thread *, and use pthread_setaffinity_np()
instead of sched_setaffinity()
- Reorder struct ublk_thread fields to group related state together
This change makes each thread's ublk_thread structure truly local to
the thread, improving cache locality and reducing memory usage.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new command line option --no_ublk_fixed_fd that excludes the ublk
control device (/dev/ublkcN) from io_uring's registered files array.
When this option is used, only backing files are registered starting
from index 1, while the ublk control device is accessed using its raw
file descriptor.
Add ublk_get_registered_fd() helper function that returns the appropriate
file descriptor for use with io_uring operations.
Key optimizations implemented:
- Cache UBLKS_Q_NO_UBLK_FIXED_FD flag in ublk_queue.flags to avoid
reading dev->no_ublk_fixed_fd in fast path
- Cache ublk char device fd in ublk_queue.ublk_fd for fast access
- Update ublk_get_registered_fd() to use ublk_queue * parameter
- Update io_uring_prep_buf_register/unregister() to use ublk_queue *
- Replace ublk_device * access with ublk_queue * access in fast paths
Also pass --no_ublk_fixed_fd to test_stress_04.sh for covering
plain ublk char device mode.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250827121602.2619736-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
'struct thread' is task local structure, and the related code will become
more readable if we pass it via parameter.
Meantime pass 'ublk_thread *' to ublk_io_alloc_sqes(), and this way is
natural since we use per-thread io_uring for handling IO.
More importantly it helps much for removing the current ubq_daemon or
per-io-task limit.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250713143415.2857561-13-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add support in kublk for decoupled ublk_queues and ublk server threads.
kublk now has two modes of operation:
- (preexisting mode) threads and queues are paired 1:1, and each thread
services all the I/Os of one queue
- (new mode) thread and queue counts are independently configurable.
threads service I/Os in a way that balances load across threads even
if load is not balanced over queues.
The default is the preexisting mode. The new mode is activated by
passing the --per_io_tasks flag.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250529-ublk_task_per_io-v8-6-e9d3b119336a@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We currently have a helper ublk_queue_alloc_sqes which the ublk targets
use to allocate SQEs for their own operations. However, as we move
towards decoupled ublk_queues and ublk server threads, this helper does
not make sense anymore. SQEs are allocated from rings, and we will have
one ring per thread to avoid locking. Change the SQE allocation helper
to ublk_io_alloc_sqes. Currently this still allocates SQEs from the io's
queue's ring, but when we fully decouple threads and queues, it will
allocate from the io's thread's ring instead.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250529-ublk_task_per_io-v8-3-e9d3b119336a@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, when we process CQEs, we know which ublk_queue we are working
on because we know which ring we are working on, and ublk_queues and
rings are in 1:1 correspondence. However, as we decouple ublk_queues
from ublk server threads, ublk_queues and rings will no longer be in 1:1
correspondence - each ublk server thread will have a ring, and each
thread may issue commands against more than one ublk_queue. So in order
to know which ublk_queue a CQE refers to, plumb that information in the
associated SQE's user_data.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250529-ublk_task_per_io-v8-2-e9d3b119336a@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add test for covering UBLK_AUTO_BUF_REG_FALLBACK:
- pass '--auto_zc_fallback' to null target, which requires both F_AUTO_BUF_REG
and F_SUPPORT_ZERO_COPY for handling UBLK_AUTO_BUF_REG_FALLBACK
- add ->buf_index() method for returning invalid buffer index to trigger
UBLK_AUTO_BUF_REG_FALLBACK
- add generic_09 for running the test
- add --auto_zc_fallback test in stress_03/stress_04/stress_05
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250520045455.515691-7-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Enable UBLK_F_AUTO_BUF_REG support for ublk utility by argument `--auto_zc`,
meantime support this feature in null, loop and stripe target code.
Add function test generic_08 for covering basic UBLK_F_AUTO_BUF_REG feature.
Also cover UBLK_F_AUTO_BUF_REG in stress_03, stress_04 and stress_05 test too.
'fio/t/io_uring -p0 /dev/ublkb0' shows that F_AUTO_BUF_REG can improve
IOPS by 50% compared with F_SUPPORT_ZERO_COPY in my test VM.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250520045455.515691-6-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Building kublk currently fails (with a "could not find linux/ublk_cmd.h"
error message) if kernel headers are not installed in a system-global
location (i.e. somewhere in the compiler's default include search path).
This failure is unnecessary, as make kselftest installs kernel headers
in the build tree - kublk's build just isn't looking for them properly.
There is an include path in kublk's CFLAGS which is probably intended to
find the kernel headers installed in the build tree; fix it so that it
can actually find them.
This introduces some macro redefinition issues between glibc-provided
headers and kernel headers; fix those by eliminating one include in
kublk.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250429-ublk_selftests-v2-3-e970b6d9e4f4@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 57e13a2e8c ("selftests: ublk: support user recovery") starts to
support UBLK_F_NEED_GET_DATA for covering recovery feature, however the
ublk utility implementation isn't done correctly.
Fix it by supporting UBLK_F_NEED_GET_DATA correctly.
Also add test generic_07 for covering UBLK_F_NEED_GET_DATA.
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 57e13a2e8c ("selftests: ublk: support user recovery")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250429022941.1718671-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In NUMA machine, ublk IO performance is very sensitive with queue
pthread's affinity setting.
Retrieve queue's affinity and select the 1st cpu as queue thread's sched
affinity, and it is observed that single cpu task affinity can get
stable & good performance if client application is put on proper cpu.
Dump this info when adding one ublk device. Use shmem to communicate
queue's tid between parent and daemon.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250412023035.2649275-9-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add io_uring UAPI header so that ublk can work with latest uapi
definition.
Fix the following build failure:
stripe.c: In function ‘stripe_to_uring_op’:
stripe.c:120:29: error: ‘IORING_OP_READV_FIXED’ undeclared (first use in this function); did you mean ‘IORING_OP_READ_FIXED’?
120 | return zc ? IORING_OP_READV_FIXED : IORING_OP_READV;
| ^~~~~~~~~~~~~~~~~~~~~
| IORING_OP_READ_FIXED
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Fixes: 57ed58c132 ("selftests: ublk: enable zero copy for stripe target")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250412023035.2649275-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add ublk stripe target which can take 1~4 underlying backing files
or block device, with stripe size 4k ~ 512K.
Add two basic tests(write verify & mkfs/mount/umount) over ublk/stripe.
This target is helpful to cover multiple IOs aiming at same
fixed/registered IO kernel buffer.
It is also capable of verifying vectored registered (kernel)buffers
in future for zero copy, so far it isn't supported yet.
Todo: support vectored registered kernel buffer for ublk/zc.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250322093218.431419-9-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
- pass 'truct dev_ctx *ctx' to target init function
- add 'private_data' to 'struct ublk_dev' for storing target specific data
- add 'private_data' to 'struct ublk_io' for storing per-IO data
- add 'tgt_ios' to 'struct ublk_io' for counting how many io_uring ios
for handling the current io command
- add helper ublk_get_io() for supporting stripe target
- add two helpers for simplifying target io handling
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250322093218.431419-6-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fixes the following build failure:
ublk//file_backed.c: In function ‘backing_file_tgt_init’:
ublk//file_backed.c:28:42: error: ‘O_DIRECT’ undeclared (first use in this function); did you mean ‘O_DIRECTORY’?
28 | fd = open(file, O_RDWR | O_DIRECT);
| ^~~~~~~~
| O_DIRECTORY
when trying to reuse this same utility for liburing test.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250303124324.3563605-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Both ublk driver and userspace heavily depends on io_uring subsystem,
and tools/testing/selftests/ should be the best place for holding this
cross-subsystem tests.
Add basic read/write IO test over this ublk null disk, and make sure ublk
working.
More tests will be added.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250228161919.2869102-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
