[dm-devel] Re: [PATCH 1/4] dm-snapshot-rework-origin-write

[Mike Snitzer]

On Mon, Oct 05 2009 at  3:00pm -0400,
Mike Snitzer <snitzer at redhat.com> wrote:

> From: Mikulas Patocka <mpatocka at redhat.com>
> 
> Rework writing to snapshot origin.
> 
> The previous code selected one exception as "primary_pe", linked all other
> exceptions on it and used reference counting to wait until all exceptions are
> reallocated. This didn't work with exceptions with different chunk sizes:
> https://bugzilla.redhat.com/show_bug.cgi?id=182659
> 
> I removed all the complexity with exceptions linking and reference counting.
> Currently, bio is linked on one exception and when that exception is
> reallocated, the bio is retried to possibly wait for other exceptions.
> 
> Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
> Signed-off-by: Mike Snitzer <snitzer at redhat.com>

FYI, I added my "Signed-off-by" because I had to update this patch to
account for changes from these upstream linux-2.6 commits:

2913808e (dm snapshot: refactor __find_pending_exception)
c6621392 (dm snapshot: avoid dropping lock in __find_pending_exception)
0cea9c78 (dm exception store: move dm_target pointer)