[PATCH v3 2/3] io_uring: add interface for getting files

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

Preparation without functional changes. Adds io_get_file(), that allows
to grab files not only into req->file.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 66 ++++++++++++++++++++++++++++++++-------------------
 1 file changed, 41 insertions(+), 25 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5ff7c602ad4d..389db6f5568b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1255,6 +1255,15 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
 	return NULL;
 }
 
+static inline void io_put_file(struct io_ring_ctx *ctx, struct file *file,
+			  bool fixed)
+{
+	if (fixed)
+		percpu_ref_put(&ctx->file_data->refs);
+	else
+		fput(file);
+}
+
 static void __io_req_do_free(struct io_kiocb *req)
 {
 	if (likely(!io_is_fallback_req(req)))
@@ -1268,12 +1277,8 @@ static void __io_req_aux_free(struct io_kiocb *req)
 	struct io_ring_ctx *ctx = req->ctx;
 
 	kfree(req->io);
-	if (req->file) {
-		if (req->flags & REQ_F_FIXED_FILE)
-			percpu_ref_put(&ctx->file_data->refs);
-		else
-			fput(req->file);
-	}
+	if (req->file)
+		io_put_file(ctx, req->file, (req->flags & REQ_F_FIXED_FILE));
 
 	io_req_work_drop_env(req);
 }
@@ -4573,41 +4578,52 @@ static inline struct file *io_file_from_index(struct io_ring_ctx *ctx,
 	return table->files[index & IORING_FILE_TABLE_MASK];;
 }
 
-static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
-			   const struct io_uring_sqe *sqe)
+static int io_get_file(struct io_submit_state *state, struct io_ring_ctx *ctx,
+			int fd, struct file **out_file, bool fixed)
 {
-	struct io_ring_ctx *ctx = req->ctx;
-	unsigned flags;
-	int fd;
-
-	flags = READ_ONCE(sqe->flags);
-	fd = READ_ONCE(sqe->fd);
-
-	if (!io_req_needs_file(req, fd))
-		return 0;
+	struct file *file;
 
-	if (flags & IOSQE_FIXED_FILE) {
+	if (fixed) {
 		if (unlikely(!ctx->file_data ||
 		    (unsigned) fd >= ctx->nr_user_files))
 			return -EBADF;
 		fd = array_index_nospec(fd, ctx->nr_user_files);
-		req->file = io_file_from_index(ctx, fd);
-		if (!req->file)
+		file = io_file_from_index(ctx, fd);
+		if (!file)
 			return -EBADF;
-		req->flags |= REQ_F_FIXED_FILE;
 		percpu_ref_get(&ctx->file_data->refs);
 	} else {
-		if (req->needs_fixed_file)
-			return -EBADF;
 		trace_io_uring_file_get(ctx, fd);
-		req->file = io_file_get(state, fd);
-		if (unlikely(!req->file))
+		file = io_file_get(state, fd);
+		if (unlikely(!file))
 			return -EBADF;
 	}
 
+	*out_file = file;
 	return 0;
 }
 
+static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
+			   const struct io_uring_sqe *sqe)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	unsigned flags;
+	int fd;
+	bool fixed;
+
+	flags = READ_ONCE(sqe->flags);
+	fd = READ_ONCE(sqe->fd);
+
+	if (!io_req_needs_file(req, fd))
+		return 0;
+
+	fixed = (flags & IOSQE_FIXED_FILE);
+	if (unlikely(!fixed && req->needs_fixed_file))
+		return -EBADF;
+
+	return io_get_file(state, ctx, fd, &req->file, fixed);
+}
+
 static int io_grab_files(struct io_kiocb *req)
 {
 	int ret = -EBADF;
-- 
2.24.0