fix ITER_PIPE interaction with direct_IO
by making sure we call iov_iter_advance() on original
iov_iter even if direct_IO (done on its copy) has returned 0.
It's a no-op for old iov_iter flavours and does the right thing
(== truncation of the stuff we'd allocated, but not filled) in
ITER_PIPE case. Failures (e.g. -EIO) get caught and dealt with
by cleanup in generic_file_read_iter().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/filemap.c b/mm/filemap.c
index 8a287df..6b965ef 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1920,7 +1920,7 @@
retval = mapping->a_ops->direct_IO(iocb, &data);
}
- if (retval > 0) {
+ if (retval >= 0) {
iocb->ki_pos += retval;
iov_iter_advance(iter, retval);
}