Commit 6746ee4c authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring/cmd: expose iowq to cmds 



When an io_uring request needs blocking context we offload it to the
io_uring's thread pool called io-wq. We can get there off ->uring_cmd
by returning -EAGAIN, but there is no straightforward way of doing that
from an asynchronous callback. Add a helper that would transfer a
command to a blocking context.

Note, we do an extra hop via task_work before io_queue_iowq(), that's a
limitation of io_uring infra we have that can likely be lifted later
if that would ever become a problem.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f735f807d7c8ba50c9452c69dfe5d3e9e535037b.1726072086.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 6d0f8dcb

include/linux/io_uring/cmd.h

+6 −0
Original line number Diff line number Diff line
@@ -48,6 +48,9 @@ void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd, 
void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,

		unsigned int issue_flags);



/* Execute the request from a blocking context */

void io_uring_cmd_issue_blocking(struct io_uring_cmd *ioucmd);



#else

static inline int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,

			      struct iov_iter *iter, void *ioucmd)
@@ -67,6 +70,9 @@ static inline void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, 
		unsigned int issue_flags)

{

}

static inline void io_uring_cmd_issue_blocking(struct io_uring_cmd *ioucmd)

{

}

#endif



/*

io_uring/io_uring.c

+11 −0
Original line number Diff line number Diff line
@@ -533,6 +533,17 @@ static void io_queue_iowq(struct io_kiocb *req) 
		io_queue_linked_timeout(link);

}



static void io_req_queue_iowq_tw(struct io_kiocb *req, struct io_tw_state *ts)

{

	io_queue_iowq(req);

}



void io_req_queue_iowq(struct io_kiocb *req)

{

	req->io_task_work.func = io_req_queue_iowq_tw;

	io_req_task_work_add(req);

}



static __cold void io_queue_deferred(struct io_ring_ctx *ctx)

{

	while (!list_empty(&ctx->defer_list)) {

io_uring/io_uring.h

+1 −0
Original line number Diff line number Diff line
@@ -94,6 +94,7 @@ int io_uring_alloc_task_context(struct task_struct *task, 


int io_ring_add_registered_file(struct io_uring_task *tctx, struct file *file,

				     int start, int end);

void io_req_queue_iowq(struct io_kiocb *req);



int io_poll_issue(struct io_kiocb *req, struct io_tw_state *ts);

int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr);

io_uring/uring_cmd.c

+7 −0
Original line number Diff line number Diff line
@@ -277,6 +277,13 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw, 
}

EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);



void io_uring_cmd_issue_blocking(struct io_uring_cmd *ioucmd)

{

	struct io_kiocb *req = cmd_to_io_kiocb(ioucmd);



	io_req_queue_iowq(req);

}



static inline int io_uring_cmd_getsockopt(struct socket *sock,

					  struct io_uring_cmd *cmd,

					  unsigned int issue_flags)