Merge tag 'iter-ubuf.2-2023-04-21' of git://git.kernel.dk/linux

Pull ITER_UBUF updates from Jens Axboe:
 "This turns singe vector imports into ITER_UBUF, rather than
  ITER_IOVEC.

  The former is more trivial to iterate and advance, and hence a bit
  more efficient. From some very unscientific testing, ~60% of all iovec
  imports are single vector"

* tag 'iter-ubuf.2-2023-04-21' of git://git.kernel.dk/linux:
  iov_iter: Mark copy_compat_iovec_from_user() noinline
  iov_iter: import single vector iovecs as ITER_UBUF
  iov_iter: convert import_single_range() to ITER_UBUF
  iov_iter: overlay struct iovec and ubuf/len
  iov_iter: set nr_segs = 1 for ITER_UBUF
  iov_iter: remove iov_iter_iovec()
  iov_iter: add iter_iov_addr() and iter_iov_len() helpers
  ALSA: pcm: check for user backed iterator, not specific iterator type
  IB/qib: check for user backed iterator, not specific iterator type
  IB/hfi1: check for user backed iterator, not specific iterator type
  iov_iter: add iter_iovec() helper
  block: ensure bio_alloc_map_data() deals with ITER_UBUF correctly

14 files changed, 165 insertions, 105 deletions

diff --git a/block/blk-map.c b/block/blk-map.c
index 9137d16cecdc..04c55f1c492e 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -29,10 +29,11 @@ static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data,
 	bmd = kmalloc(struct_size(bmd, iov, data->nr_segs), gfp_mask);
 	if (!bmd)
 		return NULL;
-	memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs);
 	bmd->iter = *data;
-	if (iter_is_iovec(data))
-		bmd->iter.iov = bmd->iov;
+	if (iter_is_iovec(data)) {
+		memcpy(bmd->iov, iter_iov(data), sizeof(struct iovec) * data->nr_segs);
+		bmd->iter.__iov = bmd->iov;
+	}
 	return bmd;
 }
 
diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c
index b1d6ca7e9708..f3d6ce45c397 100644
--- a/drivers/infiniband/hw/hfi1/file_ops.c
+++ b/drivers/infiniband/hw/hfi1/file_ops.c
@@ -267,6 +267,8 @@ static ssize_t hfi1_write_iter(struct kiocb *kiocb, struct iov_iter *from)
 
 	if (!HFI1_CAP_IS_KSET(SDMA))
 		return -EINVAL;
+	if (!from->user_backed)
+		return -EINVAL;
 	idx = srcu_read_lock(&fd->pq_srcu);
 	pq = srcu_dereference(fd->pq, &fd->pq_srcu);
 	if (!cq || !pq) {
@@ -274,11 +276,6 @@ static ssize_t hfi1_write_iter(struct kiocb *kiocb, struct iov_iter *from)
 		return -EIO;
 	}
 
-	if (!iter_is_iovec(from) || !dim) {
-		srcu_read_unlock(&fd->pq_srcu, idx);
-		return -EINVAL;
-	}
-
 	trace_hfi1_sdma_request(fd->dd, fd->uctxt->ctxt, fd->subctxt, dim);
 
 	if (atomic_read(&pq->n_reqs) == pq->n_max_reqs) {
@@ -287,11 +284,12 @@ static ssize_t hfi1_write_iter(struct kiocb *kiocb, struct iov_iter *from)
 	}
 
 	while (dim) {
+		const struct iovec *iov = iter_iov(from);
 		int ret;
 		unsigned long count = 0;
 
 		ret = hfi1_user_sdma_process_request(
-			fd, (struct iovec *)(from->iov + done),
+			fd, (struct iovec *)(iov + done),
 			dim, &count);
 		if (ret) {
 			reqs = ret;
diff --git a/drivers/infiniband/hw/qib/qib_file_ops.c b/drivers/infiniband/hw/qib/qib_file_ops.c
index 80fe92a21f96..815ea72ad473 100644
--- a/drivers/infiniband/hw/qib/qib_file_ops.c
+++ b/drivers/infiniband/hw/qib/qib_file_ops.c
@@ -2245,10 +2245,10 @@ static ssize_t qib_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct qib_ctxtdata *rcd = ctxt_fp(iocb->ki_filp);
 	struct qib_user_sdma_queue *pq = fp->pq;
 
-	if (!iter_is_iovec(from) || !from->nr_segs || !pq)
+	if (!from->user_backed || !from->nr_segs || !pq)
 		return -EINVAL;
 
-	return qib_user_sdma_writev(rcd, pq, from->iov, from->nr_segs);
+	return qib_user_sdma_writev(rcd, pq, iter_iov(from), from->nr_segs);
 }
 
 static struct class *qib_class;
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index ad653b32b2f0..5df1eba7b30a 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1486,7 +1486,8 @@ static struct sk_buff *tun_napi_alloc_frags(struct tun_file *tfile,
 	skb->truesize += skb->data_len;
 
 	for (i = 1; i < it->nr_segs; i++) {
-		size_t fragsz = it->iov[i].iov_len;
+		const struct iovec *iov = iter_iov(it);
+		size_t fragsz = iov->iov_len;
 		struct page *page;
 		void *frag;
 
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 32d0be968103..e68f7d226bc9 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -665,7 +665,7 @@ vhost_scsi_calc_sgls(struct iov_iter *iter, size_t bytes, int max_sgls)
 {
 	int sgl_count = 0;
 
-	if (!iter || !iter->iov) {
+	if (!iter || !iter_iov(iter)) {
 		pr_err("%s: iter->iov is NULL, but expected bytes: %zu"
 		       " present\n", __func__, bytes);
 		return -EINVAL;
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 5cc5a1faaef5..f649647392e0 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3730,10 +3730,15 @@ static int check_direct_read(struct btrfs_fs_info *fs_info,
 	if (!iter_is_iovec(iter))
 		return 0;
 
-	for (seg = 0; seg < iter->nr_segs; seg++)
-		for (i = seg + 1; i < iter->nr_segs; i++)
-			if (iter->iov[seg].iov_base == iter->iov[i].iov_base)
+	for (seg = 0; seg < iter->nr_segs; seg++) {
+		for (i = seg + 1; i < iter->nr_segs; i++) {
+			const struct iovec *iov1 = iter_iov(iter) + seg;
+			const struct iovec *iov2 = iter_iov(iter) + i;
+
+			if (iov1->iov_base == iov2->iov_base)
 				return -EINVAL;
+		}
+	}
 	return 0;
 }
 
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index de37a3a06a71..89d97f6188e0 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1419,7 +1419,7 @@ out:
 
 static inline unsigned long fuse_get_user_addr(const struct iov_iter *ii)
 {
-	return (unsigned long)ii->iov->iov_base + ii->iov_offset;
+	return (unsigned long)iter_iov(ii)->iov_base + ii->iov_offset;
 }
 
 static inline size_t fuse_get_frag_size(const struct iov_iter *ii,
diff --git a/fs/read_write.c b/fs/read_write.c
index 7a2ff6157eda..a21ba3be7dbe 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -749,15 +749,14 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
 		return -EOPNOTSUPP;
 
 	while (iov_iter_count(iter)) {
-		struct iovec iovec = iov_iter_iovec(iter);
 		ssize_t nr;
 
 		if (type == READ) {
-			nr = filp->f_op->read(filp, iovec.iov_base,
-					      iovec.iov_len, ppos);
+			nr = filp->f_op->read(filp, iter_iov_addr(iter),
+						iter_iov_len(iter), ppos);
 		} else {
-			nr = filp->f_op->write(filp, iovec.iov_base,
-					       iovec.iov_len, ppos);
+			nr = filp->f_op->write(filp, iter_iov_addr(iter),
+						iter_iov_len(iter), ppos);
 		}
 
 		if (nr < 0) {
@@ -766,7 +765,7 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
 			break;
 		}
 		ret += nr;
-		if (nr != iovec.iov_len)
+		if (nr != iter_iov_len(iter))
 			break;
 		iov_iter_advance(iter, nr);
 	}
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 27e3fd942960..ed35f4427a0a 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -49,14 +49,35 @@ struct iov_iter {
 		size_t iov_offset;
 		int last_offset;
 	};
-	size_t count;
+	/*
+	 * Hack alert: overlay ubuf_iovec with iovec + count, so
+	 * that the members resolve correctly regardless of the type
+	 * of iterator used. This means that you can use:
+	 *
+	 * &iter->__ubuf_iovec or iter->__iov
+	 *
+	 * interchangably for the user_backed cases, hence simplifying
+	 * some of the cases that need to deal with both.
+	 */
 	union {
-		const struct iovec *iov;
-		const struct kvec *kvec;
-		const struct bio_vec *bvec;
-		struct xarray *xarray;
-		struct pipe_inode_info *pipe;
-		void __user *ubuf;
+		/*
+		 * This really should be a const, but we cannot do that without
+		 * also modifying any of the zero-filling iter init functions.
+		 * Leave it non-const for now, but it should be treated as such.
+		 */
+		struct iovec __ubuf_iovec;
+		struct {
+			union {
+				/* use iter_iov() to get the current vec */
+				const struct iovec *__iov;
+				const struct kvec *kvec;
+				const struct bio_vec *bvec;
+				struct xarray *xarray;
+				struct pipe_inode_info *pipe;
+				void __user *ubuf;
+			};
+			size_t count;
+		};
 	};
 	union {
 		unsigned long nr_segs;
@@ -68,6 +89,16 @@ struct iov_iter {
 	};
 };
 
+static inline const struct iovec *iter_iov(const struct iov_iter *iter)
+{
+	if (iter->iter_type == ITER_UBUF)
+		return (const struct iovec *) &iter->__ubuf_iovec;
+	return iter->__iov;
+}
+
+#define iter_iov_addr(iter)	(iter_iov(iter)->iov_base + (iter)->iov_offset)
+#define iter_iov_len(iter)	(iter_iov(iter)->iov_len - (iter)->iov_offset)
+
 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
 {
 	return i->iter_type;
@@ -143,15 +174,6 @@ static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
 	return ret;
 }
 
-static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
-{
-	return (struct iovec) {
-		.iov_base = iter->iov->iov_base + iter->iov_offset,
-		.iov_len = min(iter->count,
-			       iter->iov->iov_len - iter->iov_offset),
-	};
-}
-
 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
 				  size_t bytes, struct iov_iter *i);
 void iov_iter_advance(struct iov_iter *i, size_t bytes);
@@ -359,7 +381,8 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
 		.user_backed = true,
 		.data_source = direction,
 		.ubuf = buf,
-		.count = count
+		.count = count,
+		.nr_segs = 1
 	};
 }
 /* Flags for iov_iter_get/extract_pages*() */
diff --git a/io_uring/net.c b/io_uring/net.c
index 4040cf093318..89e839013837 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -184,8 +184,8 @@ static int io_setup_async_msg(struct io_kiocb *req,
 		async_msg->msg.msg_name = &async_msg->addr;
 	/* if were using fast_iov, set it to the new one */
 	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];
+		size_t fast_idx = iter_iov(&kmsg->msg.msg_iter) - kmsg->fast_iov;
+		async_msg->msg.msg_iter.__iov = &async_msg->fast_iov[fast_idx];
 	}
 
 	return -EAGAIN;
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 4c233910e200..f33ba6f28247 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -447,26 +447,25 @@ static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
 	ppos = io_kiocb_ppos(kiocb);
 
 	while (iov_iter_count(iter)) {
-		struct iovec iovec;
+		void __user *addr;
+		size_t len;
 		ssize_t nr;
 
 		if (iter_is_ubuf(iter)) {
-			iovec.iov_base = iter->ubuf + iter->iov_offset;
-			iovec.iov_len = iov_iter_count(iter);
+			addr = iter->ubuf + iter->iov_offset;
+			len = iov_iter_count(iter);
 		} else if (!iov_iter_is_bvec(iter)) {
-			iovec = iov_iter_iovec(iter);
+			addr = iter_iov_addr(iter);
+			len = iter_iov_len(iter);
 		} else {
-			iovec.iov_base = u64_to_user_ptr(rw->addr);
-			iovec.iov_len = rw->len;
+			addr = u64_to_user_ptr(rw->addr);
+			len = rw->len;
 		}
 
-		if (ddir == READ) {
-			nr = file->f_op->read(file, iovec.iov_base,
-					      iovec.iov_len, ppos);
-		} else {
-			nr = file->f_op->write(file, iovec.iov_base,
-					       iovec.iov_len, ppos);
-		}
+		if (ddir == READ)
+			nr = file->f_op->read(file, addr, len, ppos);
+		else
+			nr = file->f_op->write(file, addr, len, ppos);
 
 		if (nr < 0) {
 			if (!ret)
@@ -482,7 +481,7 @@ static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
 			if (!rw->len)
 				break;
 		}
-		if (nr != iovec.iov_len)
+		if (nr != len)
 			break;
 	}
 
@@ -503,10 +502,10 @@ static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
 	if (!iovec) {
 		unsigned iov_off = 0;
 
-		io->s.iter.iov = io->s.fast_iov;
-		if (iter->iov != fast_iov) {
-			iov_off = iter->iov - fast_iov;
-			io->s.iter.iov += iov_off;
+		io->s.iter.__iov = io->s.fast_iov;
+		if (iter->__iov != fast_iov) {
+			iov_off = iter_iov(iter) - fast_iov;
+			io->s.iter.__iov += iov_off;
 		}
 		if (io->s.fast_iov != fast_iov)
 			memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off,
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 274014e4eafe..86a066aa9bcc 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -126,13 +126,13 @@ __out:								\
 			iterate_buf(i, n, base, len, off,	\
 						i->ubuf, (I)) 	\
 		} else if (likely(iter_is_iovec(i))) {		\
-			const struct iovec *iov = i->iov;	\
+			const struct iovec *iov = iter_iov(i);	\
 			void __user *base;			\
 			size_t len;				\
 			iterate_iovec(i, n, base, len, off,	\
 						iov, (I))	\
-			i->nr_segs -= iov - i->iov;		\
-			i->iov = iov;				\
+			i->nr_segs -= iov - iter_iov(i);	\
+			i->__iov = iov;				\
 		} else if (iov_iter_is_bvec(i)) {		\
 			const struct bio_vec *bvec = i->bvec;	\
 			void *base;				\
@@ -355,7 +355,7 @@ size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size)
 		size_t skip;
 
 		size -= count;
-		for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) {
+		for (p = iter_iov(i), skip = i->iov_offset; count; p++, skip = 0) {
 			size_t len = min(count, p->iov_len - skip);
 			size_t ret;
 
@@ -398,7 +398,7 @@ size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size)
 		size_t skip;
 
 		size -= count;
-		for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) {
+		for (p = iter_iov(i), skip = i->iov_offset; count; p++, skip = 0) {
 			size_t len = min(count, p->iov_len - skip);
 			size_t ret;
 
@@ -425,7 +425,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
 		.nofault = false,
 		.user_backed = true,
 		.data_source = direction,
-		.iov = iov,
+		.__iov = iov,
 		.nr_segs = nr_segs,
 		.iov_offset = 0,
 		.count = count
@@ -876,14 +876,14 @@ static void iov_iter_iovec_advance(struct iov_iter *i, size_t size)
 	i->count -= size;
 
 	size += i->iov_offset; // from beginning of current segment
-	for (iov = i->iov, end = iov + i->nr_segs; iov < end; iov++) {
+	for (iov = iter_iov(i), end = iov + i->nr_segs; iov < end; iov++) {
 		if (likely(size < iov->iov_len))
 			break;
 		size -= iov->iov_len;
 	}
 	i->iov_offset = size;
-	i->nr_segs -= iov - i->iov;
-	i->iov = iov;
+	i->nr_segs -= iov - iter_iov(i);
+	i->__iov = iov;
 }
 
 void iov_iter_advance(struct iov_iter *i, size_t size)
@@ -958,12 +958,12 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll)
 			unroll -= n;
 		}
 	} else { /* same logics for iovec and kvec */
-		const struct iovec *iov = i->iov;
+		const struct iovec *iov = iter_iov(i);
 		while (1) {
 			size_t n = (--iov)->iov_len;
 			i->nr_segs++;
 			if (unroll <= n) {
-				i->iov = iov;
+				i->__iov = iov;
 				i->iov_offset = n - unroll;
 				return;
 			}
@@ -980,7 +980,7 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i)
 {
 	if (i->nr_segs > 1) {
 		if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
-			return min(i->count, i->iov->iov_len - i->iov_offset);
+			return min(i->count, iter_iov(i)->iov_len - i->iov_offset);
 		if (iov_iter_is_bvec(i))
 			return min(i->count, i->bvec->bv_len - i->iov_offset);
 	}
@@ -1095,13 +1095,14 @@ static bool iov_iter_aligned_iovec(const struct iov_iter *i, unsigned addr_mask,
 	unsigned k;
 
 	for (k = 0; k < i->nr_segs; k++, skip = 0) {
-		size_t len = i->iov[k].iov_len - skip;
+		const struct iovec *iov = iter_iov(i) + k;
+		size_t len = iov->iov_len - skip;
 
 		if (len > size)
 			len = size;
 		if (len & len_mask)
 			return false;
-		if ((unsigned long)(i->iov[k].iov_base + skip) & addr_mask)
+		if ((unsigned long)(iov->iov_base + skip) & addr_mask)
 			return false;
 
 		size -= len;
@@ -1194,9 +1195,10 @@ static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i)
 	unsigned k;
 
 	for (k = 0; k < i->nr_segs; k++, skip = 0) {
-		size_t len = i->iov[k].iov_len - skip;
+		const struct iovec *iov = iter_iov(i) + k;
+		size_t len = iov->iov_len - skip;
 		if (len) {
-			res |= (unsigned long)i->iov[k].iov_base + skip;
+			res |= (unsigned long)iov->iov_base + skip;
 			if (len > size)
 				len = size;
 			res |= len;
@@ -1273,14 +1275,15 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
 		return ~0U;
 
 	for (k = 0; k < i->nr_segs; k++) {
-		if (i->iov[k].iov_len) {
-			unsigned long base = (unsigned long)i->iov[k].iov_base;
+		const struct iovec *iov = iter_iov(i) + k;
+		if (iov->iov_len) {
+			unsigned long base = (unsigned long)iov->iov_base;
 			if (v) // if not the first one
 				res |= base | v; // this start | previous end
-			v = base + i->iov[k].iov_len;
-			if (size <= i->iov[k].iov_len)
+			v = base + iov->iov_len;
+			if (size <= iov->iov_len)
 				break;
-			size -= i->iov[k].iov_len;
+			size -= iov->iov_len;
 		}
 	}
 	return res;
@@ -1396,13 +1399,14 @@ static unsigned long first_iovec_segment(const struct iov_iter *i, size_t *size)
 		return (unsigned long)i->ubuf + i->iov_offset;
 
 	for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) {
-		size_t len = i->iov[k].iov_len - skip;
+		const struct iovec *iov = iter_iov(i) + k;
+		size_t len = iov->iov_len - skip;
 
 		if (unlikely(!len))
 			continue;
 		if (*size > len)
 			*size = len;
-		return (unsigned long)i->iov[k].iov_base + skip;
+		return (unsigned long)iov->iov_base + skip;
 	}
 	BUG(); // if it had been empty, we wouldn't get called
 }
@@ -1614,7 +1618,7 @@ static int iov_npages(const struct iov_iter *i, int maxpages)
 	const struct iovec *p;
 	int npages = 0;
 
-	for (p = i->iov; size; skip = 0, p++) {
+	for (p = iter_iov(i); size; skip = 0, p++) {
 		unsigned offs = offset_in_page(p->iov_base + skip);
 		size_t len = min(p->iov_len - skip, size);
 
@@ -1691,14 +1695,14 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
 				    flags);
 	else if (iov_iter_is_kvec(new) || iter_is_iovec(new))
 		/* iovec and kvec have identical layout */
-		return new->iov = kmemdup(new->iov,
+		return new->__iov = kmemdup(new->__iov,
 				   new->nr_segs * sizeof(struct iovec),
 				   flags);
 	return NULL;
 }
 EXPORT_SYMBOL(dup_iter);
 
-static int copy_compat_iovec_from_user(struct iovec *iov,
+static __noclone int copy_compat_iovec_from_user(struct iovec *iov,
 		const struct iovec __user *uvec, unsigned long nr_segs)
 {
 	const struct compat_iovec __user *uiov =
@@ -1780,6 +1784,30 @@ struct iovec *iovec_from_user(const struct iovec __user *uvec,
 	return iov;
 }
 
+/*
+ * Single segment iovec supplied by the user, import it as ITER_UBUF.
+ */
+static ssize_t __import_iovec_ubuf(int type, const struct iovec __user *uvec,
+				   struct iovec **iovp, struct iov_iter *i,
+				   bool compat)
+{
+	struct iovec *iov = *iovp;
+	ssize_t ret;
+
+	if (compat)
+		ret = copy_compat_iovec_from_user(iov, uvec, 1);
+	else
+		ret = copy_iovec_from_user(iov, uvec, 1);
+	if (unlikely(ret))
+		return ret;
+
+	ret = import_ubuf(type, iov->iov_base, iov->iov_len, i);
+	if (unlikely(ret))
+		return ret;
+	*iovp = NULL;
+	return i->count;
+}
+
 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
 		 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
 		 struct iov_iter *i, bool compat)
@@ -1788,6 +1816,9 @@ ssize_t __import_iovec(int type, const struct iovec __user *uvec,
 	unsigned long seg;
 	struct iovec *iov;
 
+	if (nr_segs == 1)
+		return __import_iovec_ubuf(type, uvec, iovp, i, compat);
+
 	iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat);
 	if (IS_ERR(iov)) {
 		*iovp = NULL;
@@ -1866,9 +1897,7 @@ int import_single_range(int rw, void __user *buf, size_t len,
 	if (unlikely(!access_ok(buf, len)))
 		return -EFAULT;
 
-	iov->iov_base = buf;
-	iov->iov_len = len;
-	iov_iter_init(i, rw, iov, 1, len);
+	iov_iter_ubuf(i, rw, buf, len);
 	return 0;
 }
 EXPORT_SYMBOL(import_single_range);
@@ -1918,7 +1947,7 @@ void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state)
 	if (iov_iter_is_bvec(i))
 		i->bvec -= state->nr_segs - i->nr_segs;
 	else
-		i->iov -= state->nr_segs - i->nr_segs;
+		i->__iov -= state->nr_segs - i->nr_segs;
 	i->nr_segs = state->nr_segs;
 }
 
diff --git a/mm/madvise.c b/mm/madvise.c
index 340125d08c03..9f389c5304d2 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1456,7 +1456,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
 		size_t, vlen, int, behavior, unsigned int, flags)
 {
 	ssize_t ret;
-	struct iovec iovstack[UIO_FASTIOV], iovec;
+	struct iovec iovstack[UIO_FASTIOV];
 	struct iovec *iov = iovstack;
 	struct iov_iter iter;
 	struct task_struct *task;
@@ -1503,12 +1503,11 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
 	total_len = iov_iter_count(&iter);
 
 	while (iov_iter_count(&iter)) {
-		iovec = iov_iter_iovec(&iter);
-		ret = do_madvise(mm, (unsigned long)iovec.iov_base,
-					iovec.iov_len, behavior);
+		ret = do_madvise(mm, (unsigned long)iter_iov_addr(&iter),
+					iter_iov_len(&iter), behavior);
 		if (ret < 0)
 			break;
-		iov_iter_advance(&iter, iovec.iov_len);
+		iov_iter_advance(&iter, iter_iov_len(&iter));
 	}
 
 	ret = (total_len - iov_iter_count(&iter)) ? : ret;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 331380c2438b..5868661d461b 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3521,6 +3521,7 @@ static ssize_t snd_pcm_readv(struct kiocb *iocb, struct iov_iter *to)
 	unsigned long i;
 	void __user **bufs;
 	snd_pcm_uframes_t frames;
+	const struct iovec *iov = iter_iov(to);
 
 	pcm_file = iocb->ki_filp->private_data;
 	substream = pcm_file->substream;
@@ -3530,18 +3531,20 @@ static ssize_t snd_pcm_readv(struct kiocb *iocb, struct iov_iter *to)
 	if (runtime->state == SNDRV_PCM_STATE_OPEN ||
 	    runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
 		return -EBADFD;
-	if (!iter_is_iovec(to))
+	if (!to->user_backed)
 		return -EINVAL;
 	if (to->nr_segs > 1024 || to->nr_segs != runtime->channels)
 		return -EINVAL;
-	if (!frame_aligned(runtime, to->iov->iov_len))
+	if (!frame_aligned(runtime, iov->iov_len))
 		return -EINVAL;
-	frames = bytes_to_samples(runtime, to->iov->iov_len);
+	frames = bytes_to_samples(runtime, iov->iov_len);
 	bufs = kmalloc_array(to->nr_segs, sizeof(void *), GFP_KERNEL);
 	if (bufs == NULL)
 		return -ENOMEM;
-	for (i = 0; i < to->nr_segs; ++i)
-		bufs[i] = to->iov[i].iov_base;
+	for (i = 0; i < to->nr_segs; ++i) {
+		bufs[i] = iov->iov_base;
+		iov++;
+	}
 	result = snd_pcm_lib_readv(substream, bufs, frames);
 	if (result > 0)
 		result = frames_to_bytes(runtime, result);
@@ -3558,6 +3561,7 @@ static ssize_t snd_pcm_writev(struct kiocb *iocb, struct iov_iter *from)
 	unsigned long i;
 	void __user **bufs;
 	snd_pcm_uframes_t frames;
+	const struct iovec *iov = iter_iov(from);
 
 	pcm_file = iocb->ki_filp->private_data;
 	substream = pcm_file->substream;
@@ -3567,17 +3571,19 @@ static ssize_t snd_pcm_writev(struct kiocb *iocb, struct iov_iter *from)
 	if (runtime->state == SNDRV_PCM_STATE_OPEN ||
 	    runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
 		return -EBADFD;
-	if (!iter_is_iovec(from))
+	if (!from->user_backed)
 		return -EINVAL;
 	if (from->nr_segs > 128 || from->nr_segs != runtime->channels ||
-	    !frame_aligned(runtime, from->iov->iov_len))
+	    !frame_aligned(runtime, iov->iov_len))
 		return -EINVAL;
-	frames = bytes_to_samples(runtime, from->iov->iov_len);
+	frames = bytes_to_samples(runtime, iov->iov_len);
 	bufs = kmalloc_array(from->nr_segs, sizeof(void *), GFP_KERNEL);
 	if (bufs == NULL)
 		return -ENOMEM;
-	for (i = 0; i < from->nr_segs; ++i)
-		bufs[i] = from->iov[i].iov_base;
+	for (i = 0; i < from->nr_segs; ++i) {
+		bufs[i] = iov->iov_base;
+		iov++;
+	}
 	result = snd_pcm_lib_writev(substream, bufs, frames);
 	if (result > 0)
 		result = frames_to_bytes(runtime, result);