Re: [Qemu-devel] [PATCH] block/raw-posix: use seek_hole ahead of fiemap

[Tony Breeds]

On Thu, Sep 25, 2014 at 09:30:30AM +0200, Kevin Wolf wrote:

> Does this fix the problem or does it just make it less likely that it
> becomes apparent?

Sorry for not making this clearer in my commit message.

I haven't been able to reproduce the corruption with the fiemap flag
change.
 
> If there is a data corruptor, we need to fix it, not just ensure that
> only the less common environments are affected.

I agree. I believe that the FIEMAP_FLAG_SYNC flag change fixes the
corrupter and then, as you say, makes that code less commonly executed.
 
> That looks like a logically separate change, so it should probably be
> a separate patch.

Sure I can do that, and be more explicit about the reason in the commit
message.
 
> Is this fix for the corruptor? The commit message doesn't make it
> clear. If so and fiemap is safe now, why would we still prefer
> seek_hole?

The preference for seek_hole was a suggestion from Pádraig Brady , so
I'll let him defend that :) but as I said above I think it was about 
reducing the situations where fiemap was/is called.

Tony.

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