io_uring/kbuf: introduce struct io_br_sel

Rather than return addresses directly from buffer selection, add a
struct around it. No functional changes in this patch, it's in
preparation for storing more buffer related information locally, rather
than in struct io_kiocb.

Link: https://lore.kernel.org/r/20250821020750.598432-7-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 20 insertions, 14 deletions

diff --git a/io_uring/rw.c b/io_uring/rw.c
index 7fe188872279..ef94cdde5f1f 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -107,34 +107,35 @@ static int io_import_vec(int ddir, struct io_kiocb *req,
 }
 
 static int __io_import_rw_buffer(int ddir, struct io_kiocb *req,
-			     struct io_async_rw *io,
-			     unsigned int issue_flags)
+				 struct io_async_rw *io, struct io_br_sel *sel,
+				 unsigned int issue_flags)
 {
 	const struct io_issue_def *def = &io_issue_defs[req->opcode];
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
-	void __user *buf = u64_to_user_ptr(rw->addr);
 	size_t sqe_len = rw->len;
 
+	sel->addr = u64_to_user_ptr(rw->addr);
 	if (def->vectored && !(req->flags & REQ_F_BUFFER_SELECT))
-		return io_import_vec(ddir, req, io, buf, sqe_len);
+		return io_import_vec(ddir, req, io, sel->addr, sqe_len);
 
 	if (io_do_buffer_select(req)) {
-		buf = io_buffer_select(req, &sqe_len, io->buf_group, issue_flags);
-		if (!buf)
+		*sel = io_buffer_select(req, &sqe_len, io->buf_group, issue_flags);
+		if (!sel->addr)
 			return -ENOBUFS;
-		rw->addr = (unsigned long) buf;
+		rw->addr = (unsigned long) sel->addr;
 		rw->len = sqe_len;
 	}
-	return import_ubuf(ddir, buf, sqe_len, &io->iter);
+	return import_ubuf(ddir, sel->addr, sqe_len, &io->iter);
 }
 
 static inline int io_import_rw_buffer(int rw, struct io_kiocb *req,
 				      struct io_async_rw *io,
+				      struct io_br_sel *sel,
 				      unsigned int issue_flags)
 {
 	int ret;
 
-	ret = __io_import_rw_buffer(rw, req, io, issue_flags);
+	ret = __io_import_rw_buffer(rw, req, io, sel, issue_flags);
 	if (unlikely(ret < 0))
 		return ret;
 
@@ -306,10 +307,12 @@ static int __io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 
 static int io_rw_do_import(struct io_kiocb *req, int ddir)
 {
+	struct io_br_sel sel = { };
+
 	if (io_do_buffer_select(req))
 		return 0;
 
-	return io_import_rw_buffer(ddir, req, req->async_data, 0);
+	return io_import_rw_buffer(ddir, req, req->async_data, &sel, 0);
 }
 
 static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
@@ -899,7 +902,8 @@ static int io_rw_init_file(struct io_kiocb *req, fmode_t mode, int rw_type)
 	return 0;
 }
 
-static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
+static int __io_read(struct io_kiocb *req, struct io_br_sel *sel,
+		     unsigned int issue_flags)
 {
 	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
@@ -913,7 +917,7 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
 		if (unlikely(ret))
 			return ret;
 	} else if (io_do_buffer_select(req)) {
-		ret = io_import_rw_buffer(ITER_DEST, req, io, issue_flags);
+		ret = io_import_rw_buffer(ITER_DEST, req, io, sel, issue_flags);
 		if (unlikely(ret < 0))
 			return ret;
 	}
@@ -1015,9 +1019,10 @@ done:
 
 int io_read(struct io_kiocb *req, unsigned int issue_flags)
 {
+	struct io_br_sel sel = { };
 	int ret;
 
-	ret = __io_read(req, issue_flags);
+	ret = __io_read(req, &sel, issue_flags);
 	if (ret >= 0)
 		return kiocb_done(req, ret, issue_flags);
 
@@ -1027,6 +1032,7 @@ int io_read(struct io_kiocb *req, unsigned int issue_flags)
 int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
+	struct io_br_sel sel = { };
 	unsigned int cflags = 0;
 	int ret;
 
@@ -1038,7 +1044,7 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 
 	/* make it sync, multishot doesn't support async execution */
 	rw->kiocb.ki_complete = NULL;
-	ret = __io_read(req, issue_flags);
+	ret = __io_read(req, &sel, issue_flags);
 
 	/*
 	 * If we get -EAGAIN, recycle our buffer and just let normal poll