Re: [dm-devel] Re: [PATCH 12/17] bottom-layer barrier support

[Mikulas Patocka <mpatocka redhat com>]

On Tue, 28 Apr 2009, Alasdair G Kergon wrote:

> In other words, I'm asking for it to be defined and documented what the 
> target map function receives as input for one of these flush requests.
> 
> Alasdair
> -- 
> agk redhat com

It receives what it's set in dm_flush and __clone_and_map_empty_barrier.

bio is standard zero barrier with set bi_bdev and bi_rw. 
tio->info.flush_request is the sequence number of the request. (typical 
devices require just one request, dm_stripe asks for several requests for 
each striped device).

Mikulas