kernel/linux.git/io_uring/rw.c, branch v6.12.80

io_uring/rw: recycle buffers manually for non-mshot reads

2026-02-12T12:14:56+00:00

Commit d8e1dec2f860ee40623609aa6c4f22e1ee45605d upstream. The mshot side of reads already does this, but the regular read path does not. This leads to needing recycling checks sprinkled in various spots in the "go async" path, like arming poll. In preparation for getting rid of those, ensure that read recycles appropriately. Link: https://lore.kernel.org/r/20250821020750.598432-8-axboe@kernel.dk Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

Revert "io_uring/rw: drop -EOPNOTSUPP check in __io_complete_rw_common()"

2025-10-23T14:20:26+00:00

Commit 927069c4ac2cd1a37efa468596fb5b8f86db9df0 upstream. This reverts commit 90bfb28d5fa8127a113a140c9791ea0b40ab156a. Kevin reports that this commit causes an issue for him with LVM snapshots, most likely because of turning off NOWAIT support while a snapshot is being created. This makes -EOPNOTSUPP bubble back through the completion handler, where io_uring read/write handling should just retry it. Reinstate the previous check removed by the referenced commit. Cc: stable@vger.kernel.org Fixes: 90bfb28d5fa8 ("io_uring/rw: drop -EOPNOTSUPP check in __io_complete_rw_common()") Reported-by: Salvatore Bonaccorso Reported-by: Kevin Lumik Link: https://lore.kernel.org/io-uring/cceb723c-051b-4de2-9a4c-4aa82e1619ee@kernel.dk/ Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/rw: cast rw->flags assignment to rwf_t

2025-08-20T16:30:58+00:00

commit 825aea662b492571877b32aeeae13689fd9fbee4 upstream. kernel test robot reports that a recent change of the sqe->rw_flags field throws a sparse warning on 32-bit archs: >> io_uring/rw.c:291:19: sparse: sparse: incorrect type in assignment (different base types) @@ expected restricted __kernel_rwf_t [usertype] flags @@ got unsigned int @@ io_uring/rw.c:291:19: sparse: expected restricted __kernel_rwf_t [usertype] flags io_uring/rw.c:291:19: sparse: got unsigned int Force cast it to rwf_t to silence that new sparse warning. Fixes: cf73d9970ea4 ("io_uring: don't use int for ABI") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202507032211.PwSNPNSP-lkp@intel.com/ Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

block: add a rq_list type

2025-04-25T08:48:06+00:00

commit a3396b99990d8b4e5797e7b16fdeb64c15ae97bb upstream. Replace the semi-open coded request list helpers with a proper rq_list type that mirrors the bio_list and has head and tail pointers. Besides better type safety this actually allows to insert at the tail of the list, which will be useful soon. Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20241113152050.157179-5-hch@lst.de Signed-off-by: Jens Axboe Signed-off-by: Bart Van Assche Signed-off-by: Greg Kroah-Hartman

io_uring/rw: forbid multishot async reads

2025-02-27T12:30:21+00:00

commit 67b0025d19f99fb9fbb8b62e6975553c183f3a16 upstream. At the moment we can't sanely handle queuing an async request from a multishot context, so disable them. It shouldn't matter as pollable files / socekts don't normally do async. Patching it in __io_read() is not the cleanest way, but it's simpler than other options, so let's fix it there and clean up on top. Cc: stable@vger.kernel.org Reported-by: chase xd Fixes: fc68fcda04910 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/7d51732c125159d17db4fe16f51ec41b936973f8.1739919038.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/rw: fix downgraded mshot read

2025-01-09T12:33:51+00:00

commit 38fc96a58ce40257aec79b32e9b310c86907c63c upstream. The io-wq path can downgrade a multishot request to oneshot mode, however io_read_mshot() doesn't handle that and would still post multiple CQEs. That's not allowed, because io_req_post_cqe() requires stricter context requirements. The described can only happen with pollable files that don't support FMODE_NOWAIT, which is an odd combination, so if even allowed it should be fairly rare. Cc: stable@vger.kernel.org Reported-by: chase xd Fixes: bee1d5becdf5b ("io_uring: disable io-wq execution of multishot NOWAIT requests") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/c5c8c4a50a882fd581257b81bf52eee260ac29fd.1735407848.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/rw: fix missing NOWAIT check for O_DIRECT start write

2024-10-31T14:21:02+00:00

When io_uring starts a write, it'll call kiocb_start_write() to bump the super block rwsem, preventing any freezes from happening while that write is in-flight. The freeze side will grab that rwsem for writing, excluding any new writers from happening and waiting for existing writes to finish. But io_uring unconditionally uses kiocb_start_write(), which will block if someone is currently attempting to freeze the mount point. This causes a deadlock where freeze is waiting for previous writes to complete, but the previous writes cannot complete, as the task that is supposed to complete them is blocked waiting on starting a new write. This results in the following stuck trace showing that dependency with the write blocked starting a new write: task:fio state:D stack:0 pid:886 tgid:886 ppid:876 Call trace: __switch_to+0x1d8/0x348 __schedule+0x8e8/0x2248 schedule+0x110/0x3f0 percpu_rwsem_wait+0x1e8/0x3f8 __percpu_down_read+0xe8/0x500 io_write+0xbb8/0xff8 io_issue_sqe+0x10c/0x1020 io_submit_sqes+0x614/0x2110 __arm64_sys_io_uring_enter+0x524/0x1038 invoke_syscall+0x74/0x268 el0_svc_common.constprop.0+0x160/0x238 do_el0_svc+0x44/0x60 el0_svc+0x44/0xb0 el0t_64_sync_handler+0x118/0x128 el0t_64_sync+0x168/0x170 INFO: task fsfreeze:7364 blocked for more than 15 seconds. Not tainted 6.12.0-rc5-00063-g76aaf945701c #7963 with the attempting freezer stuck trying to grab the rwsem: task:fsfreeze state:D stack:0 pid:7364 tgid:7364 ppid:995 Call trace: __switch_to+0x1d8/0x348 __schedule+0x8e8/0x2248 schedule+0x110/0x3f0 percpu_down_write+0x2b0/0x680 freeze_super+0x248/0x8a8 do_vfs_ioctl+0x149c/0x1b18 __arm64_sys_ioctl+0xd0/0x1a0 invoke_syscall+0x74/0x268 el0_svc_common.constprop.0+0x160/0x238 do_el0_svc+0x44/0x60 el0_svc+0x44/0xb0 el0t_64_sync_handler+0x118/0x128 el0t_64_sync+0x168/0x170 Fix this by having the io_uring side honor IOCB_NOWAIT, and only attempt a blocking grab of the super block rwsem if it isn't set. For normal issue where IOCB_NOWAIT would always be set, this returns -EAGAIN which will have io_uring core issue a blocking attempt of the write. That will in turn also get completions run, ensuring forward progress. Since freezing requires CAP_SYS_ADMIN in the first place, this isn't something that can be triggered by a regular user. Cc: stable@vger.kernel.org # 5.10+ Reported-by: Peter Mann Link: https://lore.kernel.org/io-uring/38c94aec-81c9-4f62-b44e-1d87f5597644@sh.cz Signed-off-by: Jens Axboe

io_uring/rw: fix wrong NOWAIT check in io_rw_init_file()

2024-10-19T15:25:45+00:00

A previous commit improved how !FMODE_NOWAIT is dealt with, but inadvertently negated a check whilst doing so. This caused -EAGAIN to be returned from reading files with O_NONBLOCK set. Fix up the check for REQ_F_SUPPORT_NOWAIT. Reported-by: Julian Orth Link: https://github.com/axboe/liburing/issues/1270 Fixes: f7c913438533 ("io_uring/rw: allow pollable non-blocking attempts for !FMODE_NOWAIT") Signed-off-by: Jens Axboe

io_uring/rw: allow pollable non-blocking attempts for !FMODE_NOWAIT

2024-10-07T02:58:53+00:00

The checking for whether or not io_uring can do a non-blocking read or write attempt is gated on FMODE_NOWAIT. However, if the file is pollable, it's feasible to just check if it's currently in a state in which it can sanely receive or send _some_ data. This avoids unnecessary io-wq punts, and repeated worthless retries before doing that punt, by assuming that some data can get delivered or received if poll tells us that is true. It also allows multishot reads to properly work with these types of files, enabling a bit of a cleanup of the logic that: c9d952b9103b ("io_uring/rw: fix cflags posting for single issue multishot read") had to put in place. Signed-off-by: Jens Axboe

io_uring/rw: fix cflags posting for single issue multishot read

2024-10-06T14:05:47+00:00

If multishot gets disabled, and hence the request will get terminated rather than persist for more iterations, then posting the CQE with the right cflags is still important. Most notably, the buffer reference needs to be included. Refactor the return of __io_read() a bit, so that the provided buffer is always put correctly, and hence returned to the application. Reported-by: Sharon Rosner Link: https://github.com/axboe/liburing/issues/1257 Cc: stable@vger.kernel.org Fixes: 2a975d426c82 ("io_uring/rw: don't allow multishot reads without NOWAIT support") Signed-off-by: Jens Axboe