generic_file_direct_write(): make use of iov_iter_revert()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/mm/filemap.c b/mm/filemap.c
index 1694623a628902b76e11d6983eebd1ea7d33ddf1..9f788eecd2c53b99af0a45cddde42a6d335fb4c6 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2704,7 +2704,6 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
        ssize_t         written;
        size_t          write_len;
        pgoff_t         end;
-       struct iov_iter data;
 
        write_len = iov_iter_count(from);
        end = (pos + write_len - 1) >> PAGE_SHIFT;
@@ -2733,8 +2732,7 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
                }
        }
 
-       data = *from;
-       written = mapping->a_ops->direct_IO(iocb, &data);
+       written = mapping->a_ops->direct_IO(iocb, from);
 
        /*
         * Finally, try again to invalidate clean pages which might have been
@@ -2751,13 +2749,14 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
 
        if (written > 0) {
                pos += written;
-               iov_iter_advance(from, written);
+               write_len -= written;
                if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
                        i_size_write(inode, pos);
                        mark_inode_dirty(inode);
                }
                iocb->ki_pos = pos;
        }
+       iov_iter_revert(from, write_len - iov_iter_count(from));
 out:
        return written;
 }