From: Mike Snitzer <snitzer@redhat.com>
To: Alasdair G Kergon <agk@redhat.com>
Cc: device-mapper development <dm-devel@redhat.com>
Subject: Re: [PATCH v2 02/17] dm snapshot: add suspended flag to dm_snapshot
Date: Mon, 16 Nov 2009 13:17:17 -0500 [thread overview]
Message-ID: <20091116181716.GA17448@redhat.com> (raw)
In-Reply-To: <20091105005635.GN13375@agk-dp.fab.redhat.com>
On Wed, Nov 04 2009 at 7:56pm -0500,
Alasdair G Kergon <agk@redhat.com> wrote:
> On Tue, Oct 20, 2009 at 06:46:50PM -0400, Mike Snitzer wrote:
> > Allow the snapshot target to be able to verify its state relative to a
> > requested operation. Allows for invalid operations to be prevented,
> > e.g. an attempt handover an "old" snapshot's exceptions without it
> > having been suspended first.
>
> OK - same as we do in dm-raid1.
>
> But just be aware that:
> /* This does not get reverted if there's an error later. */
> dm_table_presuspend_targets(map);
>
> and so it's not identical to querying the dm_suspended() property directly.
Right, it is now clear that I should be using postsuspend. The handover
patch has a need to know that another snapshot target has been
suspended; setting dm-snapshot's 'suspended' in .presuspend doesn't give
us that information.
So the dm-snapshot-track-suspended-state-in-target.patch that you have
queued should be changed with: s/presuspend/postsuspend/
(the same search and replace is needed in the v7 handover patch)
Mike
next prev parent reply other threads:[~2009-11-16 18:17 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-20 22:46 [PATCH v2 00/17] snapshot-merge target Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 01/17] dm snapshot: rework writing to snapshot origin Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 02/17] dm snapshot: add suspended flag to dm_snapshot Mike Snitzer
2009-11-05 0:56 ` Alasdair G Kergon
2009-11-13 14:48 ` Mike Snitzer
2009-11-16 18:17 ` Mike Snitzer [this message]
2009-11-17 2:24 ` Alasdair G Kergon
2009-10-20 22:46 ` [PATCH v2 03/17] dm snapshot: initial support for exception handover Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 04/17] dm snapshot: exception handover improvements Mike Snitzer
2009-10-23 15:01 ` Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 05/17] dm exception store: do not read metadata if going to handover exceptions Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 06/17] dm exception store: add snapshot-merge specific methods Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 07/17] dm exception store: snapshot-merge usage accounting Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 08/17] dm snapshot: add snapshot-merge target Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 09/17] dm snapshot: merge target should not allocate new exceptions Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 10/17] dm snapshot: do not allow more than one merging snapshot Mike Snitzer
2009-10-20 22:46 ` [PATCH v2 11/17] dm snapshot: the merge procedure Mike Snitzer
2009-10-20 22:47 ` [PATCH v2 12/17] dm snapshot: queue writes to an area that is actively being merged Mike Snitzer
2009-10-20 22:47 ` [PATCH v2 13/17] dm snapshot: do not merge a chunk until active writes to it finish Mike Snitzer
2009-10-20 22:47 ` [PATCH v2 14/17] dm snapshot: make exceptions in other snapshots when merging Mike Snitzer
2009-10-20 22:47 ` [PATCH v2 15/17] dm snapshot: make exceptions if merge is dispatching to origin Mike Snitzer
2009-10-20 22:47 ` [PATCH v2 16/17] dm snapshot: redirect accesses to origin if merging snap invalidated Mike Snitzer
2009-10-20 22:47 ` [PATCH v2 17/17] dm snapshot: merge a linear region of chunks using one large IO Mike Snitzer
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