[dm-devel] Crash when IO is being submitted and block size is changed

[Mikulas Patocka]

On Thu, 28 Jun 2012, Jan Kara wrote:

> > Do you have any other ideas what to do with it?
>   Yeah, it's nasty and neither solution looks particularly appealing. One
> idea that came to my mind is: I'm trying to solve some races between direct
> IO, buffered IO, hole punching etc. by a new mapping interval lock. I'm not
> sure if it will go anywhere yet but if it does, we can fix the above race
> by taking the mapping lock for the whole block device around setting block
> size thus effectivelly disallowing any IO to it.
> 
> 								Honza
> -- 
> Jan Kara <jack at suse.cz>
> SUSE Labs, CR

What races are you trying to solve? There used to be i_alloc_mem that 
prevented direct i/o while the file is being truncated, but it disappeared 
in recent kernels...

Mikulas