This is a note to let you know that I've just added the patch titled io_uring: stop using io_wq_work as an fd placeholder to the 5.17-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: io_uring-stop-using-io_wq_work-as-an-fd-placeholder.patch and it can be found in the queue-5.17 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 2cce61fb05b92db2d4520de259695a147f59b827 Author: Jens Axboe <axboe@xxxxxxxxx> Date: Sun Apr 10 19:05:09 2022 -0600 io_uring: stop using io_wq_work as an fd placeholder [ Upstream commit 82733d168cbd3fe9dab603f05894316b99008924 ] There are two reasons why this isn't the best idea: - It's an odd area to grab a bit of storage space, hence it's an odd area to grab storage from. - It puts the 3rd io_kiocb cacheline into the hot path, where normal hot path just needs the first two. Use 'cflags' for joint fd/cflags storage. We only need fd until we successfully issue, and we only need cflags once a request is done and is completed. Fixes: 6bf9c47a3989 ("io_uring: defer file assignment") Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/io-wq.h b/fs/io-wq.h index 04d374e65e54..dbecd27656c7 100644 --- a/fs/io-wq.h +++ b/fs/io-wq.h @@ -155,7 +155,6 @@ struct io_wq_work_node *wq_stack_extract(struct io_wq_work_node *stack) struct io_wq_work { struct io_wq_work_node list; unsigned flags; - int fd; }; static inline struct io_wq_work *wq_next_work(struct io_wq_work *work) diff --git a/fs/io_uring.c b/fs/io_uring.c index d13f142793f2..d05394b0c1e6 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -864,7 +864,11 @@ struct io_kiocb { u64 user_data; u32 result; - u32 cflags; + /* fd initially, then cflags for completion */ + union { + u32 cflags; + int fd; + }; struct io_ring_ctx *ctx; struct task_struct *task; @@ -6708,9 +6712,9 @@ static bool io_assign_file(struct io_kiocb *req, unsigned int issue_flags) return true; if (req->flags & REQ_F_FIXED_FILE) - req->file = io_file_get_fixed(req, req->work.fd, issue_flags); + req->file = io_file_get_fixed(req, req->fd, issue_flags); else - req->file = io_file_get_normal(req, req->work.fd); + req->file = io_file_get_normal(req, req->fd); if (req->file) return true; @@ -7243,7 +7247,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, if (io_op_defs[opcode].needs_file) { struct io_submit_state *state = &ctx->submit_state; - req->work.fd = READ_ONCE(sqe->fd); + req->fd = READ_ONCE(sqe->fd); /* * Plug now if we have more than 2 IO left after this, and the