[PATCH 3.16 116/366] block_invalidatepage(): only release page if the full page was invalidated

Ben Hutchings
2018-10-14T23:27:28Z

From: Jeff Moyer <jmoyer@redhat.com>

commit 3172485f4f8032649c144e4aafa550e1e6179332 upstream.

Prior to commit d47992f86b30 ("mm: change invalidatepage prototype to
accept length"), an offset of 0 meant that the full page was being
invalidated. After that commit, we need to instead check the length.

Jan said:
:
: The only possible issue is that try_to_release_page() was called more
: often than necessary. Otherwise the issue is harmless but still it's good
: to have this fixed.

Link: http://lkml.kernel.org/r/x49fu5rtnzs.fsf@segfault.boston.devel.redhat.com
Fixes: d47992f86b307 ("mm: change invalidatepage prototype to accept length")
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Lukas Czerner <lczerner@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1575,7 +1575,7 @@ void block_invalidatepage(struct page *p
* The get_block cached value has been unconditionally invalidated,
* so real IO is not possible anymore.
*/
- if (offset == 0)
+ if (length == PAGE_SIZE)
try_to_release_page(page, 0);
out:
return;