Merge tag 'for-6.3/iter-ubuf-2023-02-16' of git://git.kernel.dk/linux

Pull io_uring ITER_UBUF conversion from Jens Axboe:
 "Since we now have ITER_UBUF available, switch to using it for single
  ranges as it's more efficient than ITER_IOVEC for that"

* tag 'for-6.3/iter-ubuf-2023-02-16' of git://git.kernel.dk/linux:
  block: use iter_ubuf for single range
  iov_iter: move iter_ubuf check inside restore WARN
  io_uring: use iter_ubuf for single range imports
  io_uring: switch network send/recv to ITER_UBUF
  iov: add import_ubuf()

Author: torvalds

block/blk-map.c

@@ -31,7 +31,8 @@ static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data,
 		return NULL;
 	memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs);
 	bmd->iter = *data;
-	bmd->iter.iov = bmd->iov;
+	if (iter_is_iovec(data))
+		bmd->iter.iov = bmd->iov;
 	return bmd;
 }
 
@@ -641,7 +642,7 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 		copy = true;
 	else if (iov_iter_is_bvec(iter))
 		map_bvec = true;
-	else if (!iter_is_iovec(iter))
+	else if (!user_backed_iter(iter))
 		copy = true;
 	else if (queue_virt_boundary(q))
 		copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
@@ -682,9 +683,8 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
 		    struct rq_map_data *map_data, void __user *ubuf,
 		    unsigned long len, gfp_t gfp_mask)
 {
-	struct iovec iov;
 	struct iov_iter i;
-	int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i);
+	int ret = import_ubuf(rq_data_dir(rq), ubuf, len, &i);
 
 	if (unlikely(ret < 0))
 		return ret;

include/linux/uio.h

@@ -346,6 +346,7 @@ ssize_t __import_iovec(int type, const struct iovec __user *uvec,
 		 struct iov_iter *i, bool compat);
 int import_single_range(int type, void __user *buf, size_t len,
 		 struct iovec *iov, struct iov_iter *i);
+int import_ubuf(int type, void __user *buf, size_t len, struct iov_iter *i);
 
 static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
 			void __user *buf, size_t count)

io_uring/net.c

@@ -182,7 +182,7 @@ static int io_setup_async_msg(struct io_kiocb *req,
 	if (async_msg->msg.msg_name)
 		async_msg->msg.msg_name = &async_msg->addr;
 	/* if were using fast_iov, set it to the new one */
-	if (!kmsg->free_iov) {
+	if (iter_is_iovec(&kmsg->msg.msg_iter) && !kmsg->free_iov) {
 		size_t fast_idx = kmsg->msg.msg_iter.iov - kmsg->fast_iov;
 		async_msg->msg.msg_iter.iov = &async_msg->fast_iov[fast_idx];
 	}
@@ -345,7 +345,6 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
 	struct sockaddr_storage __address;
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
 	struct msghdr msg;
-	struct iovec iov;
 	struct socket *sock;
 	unsigned flags;
 	int min_ret = 0;
@@ -379,7 +378,7 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
 	if (unlikely(!sock))
 		return -ENOTSOCK;
 
-	ret = import_single_range(ITER_SOURCE, sr->buf, sr->len, &iov, &msg.msg_iter);
+	ret = import_ubuf(ITER_SOURCE, sr->buf, sr->len, &msg.msg_iter);
 	if (unlikely(ret))
 		return ret;
 
@@ -775,10 +774,7 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 			}
 		}
 
-		kmsg->fast_iov[0].iov_base = buf;
-		kmsg->fast_iov[0].iov_len = len;
-		iov_iter_init(&kmsg->msg.msg_iter, ITER_DEST, kmsg->fast_iov, 1,
-				len);
+		iov_iter_ubuf(&kmsg->msg.msg_iter, ITER_DEST, buf, len);
 	}
 
 	flags = sr->msg_flags;
@@ -846,7 +842,6 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
 	struct msghdr msg;
 	struct socket *sock;
-	struct iovec iov;
 	unsigned int cflags;
 	unsigned flags;
 	int ret, min_ret = 0;
@@ -874,7 +869,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 		sr->buf = buf;
 	}
 
-	ret = import_single_range(ITER_DEST, sr->buf, len, &iov, &msg.msg_iter);
+	ret = import_ubuf(ITER_DEST, sr->buf, len, &msg.msg_iter);
 	if (unlikely(ret))
 		goto out_free;
 
@@ -1085,7 +1080,6 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 	struct sockaddr_storage __address;
 	struct io_sr_msg *zc = io_kiocb_to_cmd(req, struct io_sr_msg);
 	struct msghdr msg;
-	struct iovec iov;
 	struct socket *sock;
 	unsigned msg_flags;
 	int ret, min_ret = 0;
@@ -1127,8 +1121,7 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 		msg.sg_from_iter = io_sg_from_iter;
 	} else {
 		io_notif_set_extended(zc->notif);
-		ret = import_single_range(ITER_SOURCE, zc->buf, zc->len, &iov,
-					  &msg.msg_iter);
+		ret = import_ubuf(ITER_SOURCE, zc->buf, zc->len, &msg.msg_iter);
 		if (unlikely(ret))
 			return ret;
 		ret = io_notif_account_mem(zc->notif, zc->len);

io_uring/rw.c

@@ -391,7 +391,7 @@ static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req,
 			rw->len = sqe_len;
 		}
 
-		ret = import_single_range(ddir, buf, sqe_len, s->fast_iov, iter);
+		ret = import_ubuf(ddir, buf, sqe_len, iter);
 		if (ret)
 			return ERR_PTR(ret);
 		return NULL;
@@ -450,7 +450,10 @@ static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
 		struct iovec iovec;
 		ssize_t nr;
 
-		if (!iov_iter_is_bvec(iter)) {
+		if (iter_is_ubuf(iter)) {
+			iovec.iov_base = iter->ubuf + iter->iov_offset;
+			iovec.iov_len = iov_iter_count(iter);
+		} else if (!iov_iter_is_bvec(iter)) {
 			iovec = iov_iter_iovec(iter);
 		} else {
 			iovec.iov_base = u64_to_user_ptr(rw->addr);
@@ -495,7 +498,7 @@ static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
 	io->free_iovec = iovec;
 	io->bytes_done = 0;
 	/* can only be fixed buffers, no need to do anything */
-	if (iov_iter_is_bvec(iter))
+	if (iov_iter_is_bvec(iter) || iter_is_ubuf(iter))
 		return;
 	if (!iovec) {
 		unsigned iov_off = 0;

lib/iov_iter.c

@@ -1877,6 +1877,17 @@ int import_single_range(int rw, void __user *buf, size_t len,
 }
 EXPORT_SYMBOL(import_single_range);
 
+int import_ubuf(int rw, void __user *buf, size_t len, struct iov_iter *i)
+{
+	if (len > MAX_RW_COUNT)
+		len = MAX_RW_COUNT;
+	if (unlikely(!access_ok(buf, len)))
+		return -EFAULT;
+
+	iov_iter_ubuf(i, rw, buf, len);
+	return 0;
+}
+
 /**
  * iov_iter_restore() - Restore a &struct iov_iter to the same state as when
  *     iov_iter_save_state() was called.
@@ -1891,8 +1902,8 @@ EXPORT_SYMBOL(import_single_range);
  */
 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state)
 {
-	if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) &&
-			 !iov_iter_is_kvec(i) && !iter_is_ubuf(i))
+	if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i) &&
+			 !iter_is_ubuf(i)) && !iov_iter_is_kvec(i))
 		return;
 	i->iov_offset = state->iov_offset;
 	i->count = state->count;