generic_file_read_iter(): make use of iov_iter_revert()

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

1 files changed, 4 insertions, 4 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 9f788eecd2c5..cc480c07c71b 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2033,7 +2033,6 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
         if (iocb->ki_flags & IOCB_DIRECT) {
                 struct address_space *mapping = file->f_mapping;
                 struct inode *inode = mapping->host;
-                struct iov_iter data = *iter;
                 loff_t size;
 
                 size = i_size_read(inode);
@@ -2044,11 +2043,12 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 
                 file_accessed(file);
 
-                retval = mapping->a_ops->direct_IO(iocb, &data);
+                retval = mapping->a_ops->direct_IO(iocb, iter);
                 if (retval >= 0) {
                         iocb->ki_pos += retval;
-                        iov_iter_advance(iter, retval);
+                        count -= retval;
                 }
+                iov_iter_revert(iter, iov_iter_count(iter) - count);
 
                 /*
                  * Btrfs can have a short DIO read if we encounter
@@ -2059,7 +2059,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
                  * the rest of the read.  Buffered reads will not work for
                  * DAX files, so don't bother trying.
                  */
-                if (retval < 0 || !iov_iter_count(iter) || iocb->ki_pos >= size ||
+                if (retval < 0 || !count || iocb->ki_pos >= size ||
                     IS_DAX(inode))
                         goto out;
         }