[dm-devel] [RFC][PATCH] dm: add dm-power-fail target
Chris Mason
clm at fb.com
Mon Nov 24 20:18:50 UTC 2014
On Mon, Nov 24, 2014 at 3:15 PM, Josef Bacik <jbacik at fb.com> wrote:
> On 11/24/2014 02:57 PM, Zach Brown wrote:
>
> That is way complicated, I was just going to take two devices, one
> that's a linear mapping and the other that's the log, and then write
> to the log the sector+data that was written in order that it
> completes, and then have userspace do the replay. So basically do
> the flush tracking like I am, then write out chunks to the log device
> to keep a semblance of how the flushing would have affected stuff,
> something like this
>
> write a, write b, a complete, flush, b complete, flush complete
>
> would log out
>
> wrote a, flush, write b, <other writes>, <next flush>
>
> and then we have a userspace thing that could do something like
> replay all writes to a flush, do fs consistency and data consistency
> checks, walk to the next flush, rinse repeat, and that way we could
> be sure that we always have a consistent fs. This would make it
> easier to check complex fs operations (like btrfs's balance) without
> having to come up with special hacks in those operations to check
> them. I like this better because it's less DM code which means less
> swearing printks, but whichever we think will be the best thing for
> this sort of testing. Thanks,
I vote for whatever is the easiest to fit in our little programmer
brains. The more complex the tool, the less we'll trust it.
-chris
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