[dm-devel] Re: [PATCH 5/9] rqdm core: simplify suspend code

[Alasdair G Kergon <agk redhat com>]

On Fri, Oct 16, 2009 at 02:01:10PM +0900, Kiyoshi Ueda wrote:
>   o To keep the old semantics, we need to distinguish which I/Os were
>     queued before/after the suspend invocation.
>     So a special barrier-like request called 'suspend marker' was
>     introduced.

This is the key to the simplification - when dm devices can support
flushing properly (using this barrier support), there is no need for an
additional implementation of 'flush' to be embedded within any
internal suspend logic.

Alasdair