Quoting Zach Brown (2013-05-30 18:36:10) > 'stable' pages have always been a bit of a fiction. It's easy to > intentionally modify stable pages under io with some help from page > references that ignore mappings and page state. > > Here's little test that uses O_DIRECT to get the pinned aio ring pages > under IO and then has event completion stores modify them while they're > in flight. > > It's a nice quick way to test the consequences of stable pages being > modified. It can be used to burp out ratelimited csum failure kernel > messages with btrfs, for example.
Changing O_DIRECT in flight has always been a deep dark corner case, and crc errors are the expected result. Have you found anyone doing this in real life? I do like the small test program though, we should extend it into a test to make sure crcs are really crcing. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
