[PATCH 4/4] io_uring: reuse buffer updates for registration

[Pavel Begunkov <asml.silence@gmail.com>]

After registering an empty buffer table, we can reuse the code for
buffer updates to actually register buffers.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/rsrc.c | 85 +++++++++++++++++++------------------------------
 1 file changed, 32 insertions(+), 53 deletions(-)

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 958eee7b4a47..6b5ec1504dcd 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -277,9 +277,11 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 	return done ? done : err;
 }
 
-static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
-				   struct io_uring_rsrc_update2 *up,
-				   unsigned int nr_args)
+static int io_buffer_table_update(struct io_ring_ctx *ctx,
+				  struct io_rsrc_data *buf_table,
+				  struct io_uring_rsrc_update2 *up,
+				  unsigned int nr_args,
+				  unsigned *last_error)
 {
 	u64 __user *tags = u64_to_user_ptr(up->tags);
 	struct iovec fast_iov, *iov;
@@ -289,9 +291,9 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
 	__u32 done;
 	int i, err;
 
-	if (!ctx->buf_table.nr)
+	if (!buf_table->nr)
 		return -ENXIO;
-	if (up->offset + nr_args > ctx->buf_table.nr)
+	if (up->offset + nr_args > buf_table->nr)
 		return -EINVAL;
 
 	for (done = 0; done < nr_args; done++) {
@@ -316,17 +318,26 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
 			err = PTR_ERR(node);
 			break;
 		}
-		i = array_index_nospec(up->offset + done, ctx->buf_table.nr);
-		io_reset_rsrc_node(ctx, &ctx->buf_table, i);
-		ctx->buf_table.nodes[i] = node;
+		i = array_index_nospec(up->offset + done, buf_table->nr);
+		io_reset_rsrc_node(ctx, buf_table, i);
+		buf_table->nodes[i] = node;
 		if (ctx->compat)
 			user_data += sizeof(struct compat_iovec);
 		else
 			user_data += sizeof(struct iovec);
 	}
+	if (last_error)
+		*last_error = err;
 	return done ? done : err;
 }
 
+static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
+				   struct io_uring_rsrc_update2 *up,
+				   unsigned int nr_args)
+{
+	return io_buffer_table_update(ctx, &ctx->buf_table, up, nr_args, NULL);
+}
+
 static int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type,
 				     struct io_uring_rsrc_update2 *up,
 				     unsigned nr_args)
@@ -851,11 +862,8 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
 int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
 			    unsigned int nr_args, u64 __user *tags)
 {
-	struct page *last_hpage = NULL;
 	struct io_rsrc_data data;
-	struct iovec fast_iov, *iov = &fast_iov;
-	const struct iovec __user *uvec;
-	int i, ret;
+	int ret, err;
 
 	BUILD_BUG_ON(IORING_MAX_REG_BUFFERS >= (1u << 16));
 
@@ -867,51 +875,22 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
 	if (ret)
 		return ret;
 
-	if (!arg) {
-		ctx->buf_table = data;
-		return 0;
-	}
-
-	for (i = 0; i < nr_args; i++) {
-		struct io_rsrc_node *node;
-		u64 tag = 0;
-
-		uvec = (struct iovec __user *) arg;
-		iov = iovec_from_user(uvec, 1, 1, &fast_iov, ctx->compat);
-		if (IS_ERR(iov)) {
-			ret = PTR_ERR(iov);
-			break;
-		}
-		ret = io_buffer_validate(iov);
-		if (ret)
-			break;
-		if (ctx->compat)
-			arg += sizeof(struct compat_iovec);
-		else
-			arg += sizeof(struct iovec);
-
-		if (tags) {
-			if (copy_from_user(&tag, &tags[i], sizeof(tag))) {
-				ret = -EFAULT;
-				break;
-			}
-		}
+	if (arg) {
+		struct io_uring_rsrc_update2 update_arg = {
+			.tags = (u64)(unsigned long)tags,
+			.data = (u64)(unsigned long)arg,
+			.offset = 0,
+		};
 
-		node = io_sqe_buffer_register(ctx, iov, &last_hpage, tag);
-		if (IS_ERR(node)) {
-			ret = PTR_ERR(node);
-			break;
+		ret = io_buffer_table_update(ctx, &data, &update_arg, nr_args, &err);
+		if (ret != nr_args) {
+			io_clear_table_tags(&data);
+			io_rsrc_data_free(ctx, &data);
+			return err;
 		}
-		data.nodes[i] = node;
-	}
-
-	if (ret) {
-		io_clear_table_tags(&data);
-		io_rsrc_data_free(ctx, &data);
-		return ret;
 	}
 	ctx->buf_table = data;
-	return ret;
+	return 0;
 }
 
 int io_buffer_register_bvec(struct io_uring_cmd *cmd, struct request *rq,
-- 
2.48.1