generic_file_direct_write(): make use of iov_iter_revert()

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

1 files changed, 3 insertions, 4 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 1694623a6289..9f788eecd2c5 100644
--- 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;
 }