io_uring: simplify io_get_sqring

Make io_get_sqring() care only about sqes themselves, not initialising
the io_kiocb. Also, split it into get + consume, that will be helpful in
the future.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index b06188a..08f5204 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5781,8 +5781,7 @@ static void io_commit_sqring(struct io_ring_ctx *ctx)
  * used, it's important that those reads are done through READ_ONCE() to
  * prevent a re-load down the line.
  */
-static bool io_get_sqring(struct io_ring_ctx *ctx, struct io_kiocb *req,
-                         const struct io_uring_sqe **sqe_ptr)
+static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
 {
        u32 *sq_array = ctx->sq_array;
        unsigned head;
@@ -5796,25 +5795,18 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct io_kiocb *req,
         *    though the application is the one updating it.
         */
        head = READ_ONCE(sq_array[ctx->cached_sq_head & ctx->sq_mask]);
-       if (likely(head < ctx->sq_entries)) {
-               /*
-                * All io need record the previous position, if LINK vs DARIN,
-                * it can be used to mark the position of the first IO in the
-                * link list.
-                */
-               req->sequence = ctx->cached_sq_head;
-               *sqe_ptr = &ctx->sq_sqes[head];
-               req->opcode = READ_ONCE((*sqe_ptr)->opcode);
-               req->user_data = READ_ONCE((*sqe_ptr)->user_data);
-               ctx->cached_sq_head++;
-               return true;
-       }
+       if (likely(head < ctx->sq_entries))
+               return &ctx->sq_sqes[head];
 
        /* drop invalid entries */
-       ctx->cached_sq_head++;
        ctx->cached_sq_dropped++;
        WRITE_ONCE(ctx->rings->sq_dropped, ctx->cached_sq_dropped);
-       return false;
+       return NULL;
+}
+
+static inline void io_consume_sqe(struct io_ring_ctx *ctx)
+{
+       ctx->cached_sq_head++;
 }
 
 static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
@@ -5858,11 +5850,23 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
                                submitted = -EAGAIN;
                        break;
                }
-               if (!io_get_sqring(ctx, req, &sqe)) {
+               sqe = io_get_sqe(ctx);
+               if (!sqe) {
                        __io_req_do_free(req);
+                       io_consume_sqe(ctx);
                        break;
                }
 
+               /*
+                * All io need record the previous position, if LINK vs DARIN,
+                * it can be used to mark the position of the first IO in the
+                * link list.
+                */
+               req->sequence = ctx->cached_sq_head;
+               req->opcode = READ_ONCE(sqe->opcode);
+               req->user_data = READ_ONCE(sqe->user_data);
+               io_consume_sqe(ctx);
+
                /* will complete beyond this point, count as submitted */
                submitted++;