Re: [dm-devel] dm: fix discard support in dm_io

[Mike Snitzer <snitzer redhat com>]

On Fri, Nov 25 2011 at  2:28pm -0500,
Milan Broz <mbroz redhat com> wrote:

> This patch adds support for discard request to dm_io interface.
> 
> Currently dm_mirror can send REQ_DISCARD bios if running over
> discard enabled device and without support in dm_io the system
> crashes badly.
> 
> BUG: unable to handle kernel paging request at 00800000
> IP:  __bio_add_page.part.17+0xf5/0x1e0
> ...
>  bio_add_page+0x56/0x70
>  dispatch_io+0x1cf/0x240 [dm_mod]
>  ? km_get_page+0x50/0x50 [dm_mod]
>  ? vm_next_page+0x20/0x20 [dm_mod]
>  ? mirror_flush+0x130/0x130 [dm_mirror]
>  dm_io+0xdc/0x2b0 [dm_mod]
> ...
> 
> Signed-off-by: Milan Broz <mbroz redhat com>

Acked-by: Mike Snitzer <snitzer redhat com>