block_invalidatepage(): only release page if the full page was invalidated

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>

diff --git a/fs/buffer.c b/fs/buffer.c
index 9a73924..ec5dd39 100644 (file)
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1511,7 +1511,7 @@ void block_invalidatepage(struct page *page, unsigned int offset,
         * 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;