# Re: \[PATCH 4/6\] block: Optionally snapshot page contents to provide stable pages during write

- From: Martin K. Petersen \<hidden\>
- Date: 2013-01-17 03:26:36 
- List: linux-ext4
- Page: https://ratatoskr.run/linux-ext4/2013/01/70604
- Thread: https://ratatoskr.run/linux-fsdevel/2013/01/70604/t.md

```text
>>>>> "Darrick" == Darrick J Wong [ref] writes:

>> Umm, why did you move this hunk?

Darrick> I moved it so that the integrity data are generated against the
Darrick> contents of the bounce buffer because the write paths don't
Darrick> wait for writeback to finish if the snapshotting mode is
Darrick> enabled, which means (I think) that programs can wander in and
Darrick> scribble on the original page in between bio_integrity_prep and
Darrick> blk_queue_bounce.

It's also important that bio_integrity_prep() is run after partition
remapping has taken place. But it looks like that's still the case after
your change.

-- 
Martin K. Petersen	Oracle Linux Engineering
```