io_uring: abstract out a bit of the ring filling logic

Abstract out a io_uring_fill_params() helper, which fills out the
necessary bits of struct io_uring_params. Add it to io_uring.h as well,
in preparation for having another internal user of it.

Signed-off-by: Jens Axboe <[email protected]>

Author: axboe

io_uring/io_uring.c

@@ -3498,14 +3498,8 @@ static struct file *io_uring_get_file(struct io_ring_ctx *ctx)
 					 O_RDWR | O_CLOEXEC, NULL);
 }
 
-static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
-				  struct io_uring_params __user *params)
+int io_uring_fill_params(unsigned entries, struct io_uring_params *p)
 {
-	struct io_ring_ctx *ctx;
-	struct io_uring_task *tctx;
-	struct file *file;
-	int ret;
-
 	if (!entries)
 		return -EINVAL;
 	if (entries > IORING_MAX_ENTRIES) {
@@ -3547,6 +3541,42 @@ static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
 		p->cq_entries = 2 * p->sq_entries;
 	}
 
+	p->sq_off.head = offsetof(struct io_rings, sq.head);
+	p->sq_off.tail = offsetof(struct io_rings, sq.tail);
+	p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
+	p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
+	p->sq_off.flags = offsetof(struct io_rings, sq_flags);
+	p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
+	p->sq_off.resv1 = 0;
+	if (!(p->flags & IORING_SETUP_NO_MMAP))
+		p->sq_off.user_addr = 0;
+
+	p->cq_off.head = offsetof(struct io_rings, cq.head);
+	p->cq_off.tail = offsetof(struct io_rings, cq.tail);
+	p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
+	p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
+	p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
+	p->cq_off.cqes = offsetof(struct io_rings, cqes);
+	p->cq_off.flags = offsetof(struct io_rings, cq_flags);
+	p->cq_off.resv1 = 0;
+	if (!(p->flags & IORING_SETUP_NO_MMAP))
+		p->cq_off.user_addr = 0;
+
+	return 0;
+}
+
+static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
+				  struct io_uring_params __user *params)
+{
+	struct io_ring_ctx *ctx;
+	struct io_uring_task *tctx;
+	struct file *file;
+	int ret;
+
+	ret = io_uring_fill_params(entries, p);
+	if (unlikely(ret))
+		return ret;
+
 	ctx = io_ring_ctx_alloc(p);
 	if (!ctx)
 		return -ENOMEM;
@@ -3630,6 +3660,9 @@ static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
 	if (ret)
 		goto err;
 
+	if (!(p->flags & IORING_SETUP_NO_SQARRAY))
+		p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
+
 	ret = io_sq_offload_create(ctx, p);
 	if (ret)
 		goto err;
@@ -3638,29 +3671,6 @@ static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
 	if (ret)
 		goto err;
 
-	p->sq_off.head = offsetof(struct io_rings, sq.head);
-	p->sq_off.tail = offsetof(struct io_rings, sq.tail);
-	p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
-	p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
-	p->sq_off.flags = offsetof(struct io_rings, sq_flags);
-	p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
-	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
-		p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
-	p->sq_off.resv1 = 0;
-	if (!(ctx->flags & IORING_SETUP_NO_MMAP))
-		p->sq_off.user_addr = 0;
-
-	p->cq_off.head = offsetof(struct io_rings, cq.head);
-	p->cq_off.tail = offsetof(struct io_rings, cq.tail);
-	p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
-	p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
-	p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
-	p->cq_off.cqes = offsetof(struct io_rings, cqes);
-	p->cq_off.flags = offsetof(struct io_rings, cq_flags);
-	p->cq_off.resv1 = 0;
-	if (!(ctx->flags & IORING_SETUP_NO_MMAP))
-		p->cq_off.user_addr = 0;
-
 	p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP |
 			IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS |
 			IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL |

io_uring/io_uring.h

@@ -70,6 +70,7 @@ static inline bool io_should_wake(struct io_wait_queue *iowq)
 
 unsigned long rings_size(unsigned int flags, unsigned int sq_entries,
 			 unsigned int cq_entries, size_t *sq_offset);
+int io_uring_fill_params(unsigned entries, struct io_uring_params *p);
 bool io_cqe_cache_refill(struct io_ring_ctx *ctx, bool overflow);
 int io_run_task_work_sig(struct io_ring_ctx *ctx);
 void io_req_defer_failed(struct io_kiocb *req, s32 res);