Re: [PATCH v3 0/3] data integrity: Stabilize pages during writeback for ext4

Chris Mason
2011-05-04T19:22:55Z

Excerpts from Christoph Hellwig's message of 2011-05-04 14:46:44 -0400:
> This seems to miss out on a lot of the generic functionality like
> write_cache_pages and block_page_mkwrite and just patch it into
> the ext4 copy & paste variants. Please make sure your patches also
> work for filesystem that use more of the generic functionality like
> xfs or ext2 (the latter one might be fun for the mmap case).

Probably after the block_commit_write in block_page_mkwrite()
Another question is, do we want to introduce a wait_on_stable_page_writeback()?

This would allow us to add a check against the bdi requesting stable
pages.

>
> Also what's the status of btrfs? I remembered there was one or two
> bits missing despite doing the right thing in most areas.

As far as I know btrfs is getting it right. The only bit missing is the
one Nick Piggin pointed out where it is possible to change mmap'd O_DIRECT
memory in flight while a DIO is in progress. Josef has a test case that
demonstrates this.

Nick had a plan to fix it, but it involved redoing the get_user_pages
api.

-chris