[RFC PATCH 03/22] fuse: convert fuse to use iov_iter_copy_[to|from]_user

[Dave Kleikamp <dave.kleikamp@oracle.com>]

A future patch hides the internals of struct iov_iter, so fuse should
be using the supported interface.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: fuse-devel@lists.sourceforge.net
---
 fs/fuse/file.c |   29 ++++++++---------------------
 1 file changed, 8 insertions(+), 21 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 4a199fd..877cee0 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1582,30 +1582,17 @@ static int fuse_ioctl_copy_user(struct page **pages, struct iovec *iov,
 	while (iov_iter_count(&ii)) {
 		struct page *page = pages[page_idx++];
 		size_t todo = min_t(size_t, PAGE_SIZE, iov_iter_count(&ii));
-		void *kaddr;
+		size_t left;
 
-		kaddr = kmap(page);
-
-		while (todo) {
-			char __user *uaddr = ii.iov->iov_base + ii.iov_offset;
-			size_t iov_len = ii.iov->iov_len - ii.iov_offset;
-			size_t copy = min(todo, iov_len);
-			size_t left;
-
-			if (!to_user)
-				left = copy_from_user(kaddr, uaddr, copy);
-			else
-				left = copy_to_user(uaddr, kaddr, copy);
-
-			if (unlikely(left))
-				return -EFAULT;
+		if (!to_user)
+			left = iov_iter_copy_from_user(page, &ii, 0, todo);
+		else
+			left = iov_iter_copy_to_user(page, &ii, 0, todo);
 
-			iov_iter_advance(&ii, copy);
-			todo -= copy;
-			kaddr += copy;
-		}
+		if (unlikely(left))
+			return -EFAULT;
 
-		kunmap(page);
+		iov_iter_advance(&ii, todo);
 	}
 
 	return 0;
-- 
1.7.9.2