[PATCH 0/2] unify registered buffer iovec imports

[PATCH 0/2] unify registered buffer iovec imports

[Pavel Begunkov]

Extract a helper for some common chunks of registered buffer iovec
handling so that callers don't have to care about offsets.

Pavel Begunkov (2):
  io_uring: introduce io_prep_reg_iovec()
  io_uring: rely on io_prep_reg_vec for iovec placement

 io_uring/net.c  | 27 ++++-----------------------
 io_uring/rsrc.c | 34 ++++++++++++++++++++++++++++++----
 io_uring/rsrc.h |  5 +++--
 io_uring/rw.c   | 24 ++----------------------
 4 files changed, 39 insertions(+), 51 deletions(-)

-- 
2.48.1

[PATCH 1/2] io_uring: introduce io_prep_reg_iovec()

[Pavel Begunkov]

iovecs that are turned into registered buffers are imported in a special
way with an offset, so that later we can do an in place translation. Add
a helper function taking care of it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/net.c  | 23 +++--------------------
 io_uring/rsrc.c | 26 ++++++++++++++++++++++++++
 io_uring/rsrc.h |  2 ++
 io_uring/rw.c   | 21 +--------------------
 4 files changed, 32 insertions(+), 40 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index 9fa5c9570875..6b8dbadf445f 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -403,9 +403,7 @@ static int io_sendmsg_zc_setup(struct io_kiocb *req, const struct io_uring_sqe *
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
 	struct io_async_msghdr *kmsg = req->async_data;
 	struct user_msghdr msg;
-	int ret, iovec_off;
-	struct iovec *iov;
-	void *res;
+	int ret;
 
 	if (!(sr->flags & IORING_RECVSEND_FIXED_BUF))
 		return io_sendmsg_setup(req, sqe);
@@ -416,24 +414,9 @@ static int io_sendmsg_zc_setup(struct io_kiocb *req, const struct io_uring_sqe *
 	if (unlikely(ret))
 		return ret;
 	sr->msg_control = kmsg->msg.msg_control_user;
-
-	if (msg.msg_iovlen > kmsg->vec.nr || WARN_ON_ONCE(!kmsg->vec.iovec)) {
-		ret = io_vec_realloc(&kmsg->vec, msg.msg_iovlen);
-		if (ret)
-			return ret;
-		req->flags |= REQ_F_NEED_CLEANUP;
-	}
-	iovec_off = kmsg->vec.nr - msg.msg_iovlen;
-	iov = kmsg->vec.iovec + iovec_off;
-
-	res = iovec_from_user(msg.msg_iov, msg.msg_iovlen, kmsg->vec.nr, iov,
-			      io_is_compat(req->ctx));
-	if (IS_ERR(res))
-		return PTR_ERR(res);
-
 	kmsg->msg.msg_iter.nr_segs = msg.msg_iovlen;
-	req->flags |= REQ_F_IMPORT_BUFFER;
-	return ret;
+
+	return io_prep_reg_iovec(req, &kmsg->vec, msg.msg_iov, msg.msg_iovlen);
 }
 
 #define SENDMSG_FLAGS (IORING_RECVSEND_POLL_FIRST | IORING_RECVSEND_BUNDLE)
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 71fe47facd4c..0e413e910f3d 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1397,3 +1397,29 @@ int io_import_reg_vec(int ddir, struct iov_iter *iter,
 
 	return io_vec_fill_bvec(ddir, iter, imu, iov, nr_iovs, vec);
 }
+
+int io_prep_reg_iovec(struct io_kiocb *req, struct iou_vec *iv,
+		      const struct iovec __user *uvec, size_t uvec_segs)
+{
+	struct iovec *iov;
+	int iovec_off, ret;
+	void *res;
+
+	if (uvec_segs > iv->nr) {
+		ret = io_vec_realloc(iv, uvec_segs);
+		if (ret)
+			return ret;
+		req->flags |= REQ_F_NEED_CLEANUP;
+	}
+
+	/* pad iovec to the right */
+	iovec_off = iv->nr - uvec_segs;
+	iov = iv->iovec + iovec_off;
+	res = iovec_from_user(uvec, uvec_segs, uvec_segs, iov,
+			      io_is_compat(req->ctx));
+	if (IS_ERR(res))
+		return PTR_ERR(res);
+
+	req->flags |= REQ_F_IMPORT_BUFFER;
+	return 0;
+}
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index b0097c06b577..43f784915573 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -67,6 +67,8 @@ int io_import_reg_vec(int ddir, struct iov_iter *iter,
 			struct io_kiocb *req, struct iou_vec *vec,
 			unsigned nr_iovs, unsigned iovec_off,
 			unsigned issue_flags);
+int io_prep_reg_iovec(struct io_kiocb *req, struct iou_vec *iv,
+			const struct iovec __user *uvec, size_t uvec_segs);
 
 int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg);
 int io_sqe_buffers_unregister(struct io_ring_ctx *ctx);
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 50037313555f..4861b876f48e 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -407,28 +407,9 @@ static int io_rw_prep_reg_vec(struct io_kiocb *req)
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 	struct io_async_rw *io = req->async_data;
 	const struct iovec __user *uvec;
-	size_t uvec_segs = rw->len;
-	struct iovec *iov;
-	int iovec_off, ret;
-	void *res;
 
-	if (uvec_segs > io->vec.nr) {
-		ret = io_vec_realloc(&io->vec, uvec_segs);
-		if (ret)
-			return ret;
-		req->flags |= REQ_F_NEED_CLEANUP;
-	}
-	/* pad iovec to the right */
-	iovec_off = io->vec.nr - uvec_segs;
-	iov = io->vec.iovec + iovec_off;
 	uvec = u64_to_user_ptr(rw->addr);
-	res = iovec_from_user(uvec, uvec_segs, uvec_segs, iov,
-			      io_is_compat(req->ctx));
-	if (IS_ERR(res))
-		return PTR_ERR(res);
-
-	req->flags |= REQ_F_IMPORT_BUFFER;
-	return 0;
+	return io_prep_reg_iovec(req, &io->vec, uvec, rw->len);
 }
 
 int io_prep_readv_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe)
-- 
2.48.1

[PATCH 2/2] io_uring: rely on io_prep_reg_vec for iovec placement

[Pavel Begunkov]

All vectored reg buffer users should use io_import_reg_vec() for iovec
imports, since iovec placement is the function's responsibility and
callers shouldn't know much about it, drop the offset parameter from
io_prep_reg_vec() and calculate it inside.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/net.c  | 4 +---
 io_uring/rsrc.c | 8 ++++----
 io_uring/rsrc.h | 3 +--
 io_uring/rw.c   | 3 +--
 4 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index 6b8dbadf445f..1e36a72e4008 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -1513,12 +1513,10 @@ int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (req->flags & REQ_F_IMPORT_BUFFER) {
 		unsigned uvec_segs = kmsg->msg.msg_iter.nr_segs;
-		unsigned iovec_off = kmsg->vec.nr - uvec_segs;
 		int ret;
 
 		ret = io_import_reg_vec(ITER_SOURCE, &kmsg->msg.msg_iter, req,
-					&kmsg->vec, uvec_segs, iovec_off,
-					issue_flags);
+					&kmsg->vec, uvec_segs, issue_flags);
 		if (unlikely(ret))
 			return ret;
 		kmsg->msg.sg_from_iter = io_sg_from_iter;
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 0e413e910f3d..607b09bd8374 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1349,11 +1349,11 @@ static int io_estimate_bvec_size(struct iovec *iov, unsigned nr_iovs,
 
 int io_import_reg_vec(int ddir, struct iov_iter *iter,
 			struct io_kiocb *req, struct iou_vec *vec,
-			unsigned nr_iovs, unsigned iovec_off,
-			unsigned issue_flags)
+			unsigned nr_iovs, unsigned issue_flags)
 {
 	struct io_rsrc_node *node;
 	struct io_mapped_ubuf *imu;
+	unsigned iovec_off;
 	struct iovec *iov;
 	unsigned nr_segs;
 
@@ -1366,6 +1366,7 @@ int io_import_reg_vec(int ddir, struct iov_iter *iter,
 	if (!(imu->dir & (1 << ddir)))
 		return -EFAULT;
 
+	iovec_off = vec->nr - nr_iovs;
 	iov = vec->iovec + iovec_off;
 	nr_segs = io_estimate_bvec_size(iov, nr_iovs, imu);
 
@@ -1377,8 +1378,7 @@ int io_import_reg_vec(int ddir, struct iov_iter *iter,
 		nr_segs += nr_iovs;
 	}
 
-	if (WARN_ON_ONCE(iovec_off + nr_iovs != vec->nr) ||
-	    nr_segs > vec->nr) {
+	if (nr_segs > vec->nr) {
 		struct iou_vec tmp_vec = {};
 		int ret;
 
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 43f784915573..b52242852ff3 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -65,8 +65,7 @@ int io_import_reg_buf(struct io_kiocb *req, struct iov_iter *iter,
 			unsigned issue_flags);
 int io_import_reg_vec(int ddir, struct iov_iter *iter,
 			struct io_kiocb *req, struct iou_vec *vec,
-			unsigned nr_iovs, unsigned iovec_off,
-			unsigned issue_flags);
+			unsigned nr_iovs, unsigned issue_flags);
 int io_prep_reg_iovec(struct io_kiocb *req, struct iou_vec *iv,
 			const struct iovec __user *uvec, size_t uvec_segs);
 
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 4861b876f48e..246b22225919 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -390,11 +390,10 @@ static int io_rw_import_reg_vec(struct io_kiocb *req,
 {
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 	unsigned uvec_segs = rw->len;
-	unsigned iovec_off = io->vec.nr - uvec_segs;
 	int ret;
 
 	ret = io_import_reg_vec(ddir, &io->iter, req, &io->vec,
-				uvec_segs, iovec_off, issue_flags);
+				uvec_segs, issue_flags);
 	if (unlikely(ret))
 		return ret;
 	iov_iter_save_state(&io->iter, &io->iter_state);
-- 
2.48.1

Re: [PATCH 0/2] unify registered buffer iovec imports

[Jens Axboe]

On Sat, 08 Mar 2025 18:21:14 +0000, Pavel Begunkov wrote:
> Extract a helper for some common chunks of registered buffer iovec
> handling so that callers don't have to care about offsets.
> 
> Pavel Begunkov (2):
>   io_uring: introduce io_prep_reg_iovec()
>   io_uring: rely on io_prep_reg_vec for iovec placement
> 
> [...]

Applied, thanks!

[1/2] io_uring: introduce io_prep_reg_iovec()
      commit: d291fb65202051e996cd983b29dce3e390421bc6
[2/2] io_uring: rely on io_prep_reg_vec for iovec placement
      commit: 146acfd0f6494579996ae4168967cc5ada7d0e5a

Best regards,
-- 
Jens Axboe