From d625c6ee4975000140c57da7e1ff244efefde274 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 17 Dec 2019 19:53:05 -0700 Subject: io_uring: read opcode and user_data from SQE exactly once If we defer a request, we can't be reading the opcode again. Ensure that the user_data and opcode fields are stable. For the user_data we already have a place for it, for the opcode we can fill a one byte hold and store that as well. For both of them, assign them when we originally read the SQE in io_get_sqring(). Any code that uses sqe->opcode or sqe->user_data is switched to req->opcode and req->user_data. Signed-off-by: Jens Axboe --- fs/io_uring.c | 45 ++++++++++++++++++++------------------------- 1 file changed, 20 insertions(+), 25 deletions(-) (limited to 'fs/io_uring.c') diff --git a/fs/io_uring.c b/fs/io_uring.c index 9d4f8274ee1e..e0fc195d0d2d 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -384,6 +384,7 @@ struct io_kiocb { bool has_user; bool in_async; bool needs_fixed_file; + u8 opcode; struct io_ring_ctx *ctx; union { @@ -597,12 +598,10 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx) } } -static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe) +static inline bool io_req_needs_user(struct io_kiocb *req) { - u8 opcode = READ_ONCE(sqe->opcode); - - return !(opcode == IORING_OP_READ_FIXED || - opcode == IORING_OP_WRITE_FIXED); + return !(req->opcode == IORING_OP_READ_FIXED || + req->opcode == IORING_OP_WRITE_FIXED); } static inline bool io_prep_async_work(struct io_kiocb *req, @@ -611,7 +610,7 @@ static inline bool io_prep_async_work(struct io_kiocb *req, bool do_hashed = false; if (req->sqe) { - switch (req->sqe->opcode) { + switch (req->opcode) { case IORING_OP_WRITEV: case IORING_OP_WRITE_FIXED: /* only regular files should be hashed for writes */ @@ -634,7 +633,7 @@ static inline bool io_prep_async_work(struct io_kiocb *req, req->work.flags |= IO_WQ_WORK_UNBOUND; break; } - if (io_sqe_needs_user(req->sqe)) + if (io_req_needs_user(req)) req->work.flags |= IO_WQ_WORK_NEEDS_USER; } @@ -1005,7 +1004,7 @@ static void io_fail_links(struct io_kiocb *req) trace_io_uring_fail_link(req, link); if ((req->flags & REQ_F_LINK_TIMEOUT) && - link->sqe->opcode == IORING_OP_LINK_TIMEOUT) { + link->opcode == IORING_OP_LINK_TIMEOUT) { io_link_cancel_timeout(link); } else { io_cqring_fill_event(link, -ECANCELED); @@ -1648,7 +1647,7 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req, * for that purpose and instead let the caller pass in the read/write * flag. */ - opcode = READ_ONCE(sqe->opcode); + opcode = req->opcode; if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) { *iovec = NULL; return io_import_fixed(req->ctx, rw, sqe, iter); @@ -3082,7 +3081,7 @@ static int io_req_defer_prep(struct io_kiocb *req) struct iov_iter iter; ssize_t ret; - switch (io->sqe.opcode) { + switch (req->opcode) { case IORING_OP_READV: case IORING_OP_READ_FIXED: /* ensure prep does right import */ @@ -3181,11 +3180,10 @@ __attribute__((nonnull)) static int io_issue_sqe(struct io_kiocb *req, struct io_kiocb **nxt, bool force_nonblock) { - int ret, opcode; struct io_ring_ctx *ctx = req->ctx; + int ret; - opcode = READ_ONCE(req->sqe->opcode); - switch (opcode) { + switch (req->opcode) { case IORING_OP_NOP: ret = io_nop(req); break; @@ -3322,11 +3320,9 @@ static bool io_req_op_valid(int op) return op >= IORING_OP_NOP && op < IORING_OP_LAST; } -static int io_op_needs_file(const struct io_uring_sqe *sqe) +static int io_req_needs_file(struct io_kiocb *req) { - int op = READ_ONCE(sqe->opcode); - - switch (op) { + switch (req->opcode) { case IORING_OP_NOP: case IORING_OP_POLL_REMOVE: case IORING_OP_TIMEOUT: @@ -3335,7 +3331,7 @@ static int io_op_needs_file(const struct io_uring_sqe *sqe) case IORING_OP_LINK_TIMEOUT: return 0; default: - if (io_req_op_valid(op)) + if (io_req_op_valid(req->opcode)) return 1; return -EINVAL; } @@ -3362,7 +3358,7 @@ static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req) if (flags & IOSQE_IO_DRAIN) req->flags |= REQ_F_IO_DRAIN; - ret = io_op_needs_file(req->sqe); + ret = io_req_needs_file(req); if (ret <= 0) return ret; @@ -3482,7 +3478,7 @@ static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req) nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb, link_list); - if (!nxt || nxt->sqe->opcode != IORING_OP_LINK_TIMEOUT) + if (!nxt || nxt->opcode != IORING_OP_LINK_TIMEOUT) return NULL; req->flags |= REQ_F_LINK_TIMEOUT; @@ -3584,8 +3580,6 @@ static bool io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state, struct io_ring_ctx *ctx = req->ctx; int ret; - req->user_data = req->sqe->user_data; - /* enforce forwards compatibility on users */ if (unlikely(req->sqe->flags & ~SQE_VALID_FLAGS)) { ret = -EINVAL; @@ -3717,6 +3711,8 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct io_kiocb *req) */ req->sequence = ctx->cached_sq_head; req->sqe = &ctx->sq_sqes[head]; + req->opcode = READ_ONCE(req->sqe->opcode); + req->user_data = READ_ONCE(req->sqe->user_data); ctx->cached_sq_head++; return true; } @@ -3762,7 +3758,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr, break; } - if (io_sqe_needs_user(req->sqe) && !*mm) { + if (io_req_needs_user(req) && !*mm) { mm_fault = mm_fault || !mmget_not_zero(ctx->sqo_mm); if (!mm_fault) { use_mm(ctx->sqo_mm); @@ -3778,8 +3774,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr, req->has_user = *mm != NULL; req->in_async = async; req->needs_fixed_file = async; - trace_io_uring_submit_sqe(ctx, req->sqe->user_data, - true, async); + trace_io_uring_submit_sqe(ctx, req->user_data, true, async); if (!io_submit_sqe(req, statep, &link)) break; /* -- cgit