diff mbox series

[RFC,06/37] copy_page_to_iter(): fix ITER_DISCARD case

Message ID 20210606191051.1216821-6-viro@zeniv.linux.org.uk (mailing list archive)
State New, archived
Headers show
Series [RFC,01/37] ntfs_copy_from_user_iter(): don't bother with copying iov_iter | expand

Commit Message

Al Viro June 6, 2021, 7:10 p.m. UTC 
we need to advance the iterator...

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 lib/iov_iter.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 12fb04b23143..c8877cffb7bc 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -965,9 +965,12 @@  static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes
 		size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
 		kunmap_atomic(kaddr);
 		return wanted;
-	} else if (unlikely(iov_iter_is_discard(i)))
+	} else if (unlikely(iov_iter_is_discard(i))) {
+		if (unlikely(i->count < bytes))
+			bytes = i->count;
+		i->count -= bytes;
 		return bytes;
-	else if (likely(!iov_iter_is_pipe(i)))
+	} else if (likely(!iov_iter_is_pipe(i)))
 		return copy_page_to_iter_iovec(page, offset, bytes, i);
 	else
 		return copy_page_to_iter_pipe(page, offset, bytes, i);