[dm-devel] [PATCH 5/5] dm thin: unroll issue_discard() to create longer discard bio chains
Joe Thornber
thornber at redhat.com
Fri May 6 16:36:58 UTC 2016
On Fri, May 06, 2016 at 06:12:16PM +0200, Christoph Hellwig wrote:
> On Thu, May 05, 2016 at 11:54:25AM -0400, Mike Snitzer wrote:
> > From: Joe Thornber <ejt at redhat.com>
> >
> > There is little benefit to doing this but it does structure DM thinp's
> > code to more cleanly use the __blkdev_issue_discard() interface --
> > particularly in passdown_double_checking_shared_status().
>
> As-is I think it makes the code a whole lot more convoluted, and especially
> the structure that's just used to communicated 4 parameters between
> functions which don't even use all of them isn't very helpful.
I started coding it inline, and then factored it out because I thought
it was cleaner. I'm also likely to lift it into a separate file for
use in dm-cache too.
> This is a useful helper I think, but passing tc and bio directly would
> make it even more obvious.
y, this is exactly what I had.
> Both the plugging and the bi_error handling would benefit from being
> moved into process_prepared_discard_passdown and handled in the common
> path.
But the plugging and error handling are called from two places.
process_prepared_discard_passdown() and
passdown_double_checking_shared_status().
- Joe
(I agree about the confusing comment, we'll remove)
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