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From: Eric Blake <eblake@redhat.com>
To: John Snow <jsnow@redhat.com>,
	Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	"qemu-block@nongnu.org" <qemu-block@nongnu.org>
Cc: Fam Zheng <fam@euphon.net>, Kevin Wolf <kwolf@redhat.com>,
	Juan Quintela <quintela@redhat.com>,
	Markus Armbruster <armbru@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Max Reitz <mreitz@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v3 6/7] block/dirty-bitmaps: disallow busy bitmaps as merge source
Date: Wed, 6 Mar 2019 09:29:25 -0600	[thread overview]
Message-ID: <c2065cc3-7599-d7a6-17b5-c1362b02b5c2@redhat.com> (raw)
In-Reply-To: <7c1549db-3a4c-9100-ed7b-5e8bce39081b@redhat.com>

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On 3/6/19 9:24 AM, John Snow wrote:

>>>
>>> We could always split it back out later, but in basic terms for
>>> permissions and user perspective, "in use" seems robust enough of a
>>> resolution. (It might be safe to read, it might not be, who knows --
>>> it's in use.)
>>
>> I think, if we need some kind of sharing busy bitmaps, it should be two
>> busy states: one, which allows reads for other users and one that doesn't.
>>

Indeed, similar to flock having shared (multiple read-only users) and
exclusive (single writer) locks.  So it's nice to know we have a
technical plan for growth, if we have a reason to use that plan.

> 
> I think that's... hopefully premature. We don't need this NOW do we?

No, we don't need it now.

> 
> I think this is OK as-is.

It sounds like we are in violent agreement ;)

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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  reply	other threads:[~2019-03-06 15:29 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-01 19:15 [Qemu-devel] [PATCH v3 0/7] bitmaps: add inconsistent bit John Snow
2019-03-01 19:15 ` [Qemu-devel] [PATCH v3 1/7] block/dirty-bitmaps: " John Snow
2019-03-01 19:32   ` Eric Blake
2019-03-01 19:44     ` John Snow
2019-03-06 12:25   ` Vladimir Sementsov-Ogievskiy
2019-03-06 13:06     ` Vladimir Sementsov-Ogievskiy
2019-03-06 13:08       ` Vladimir Sementsov-Ogievskiy
2019-03-06 15:15     ` John Snow
2019-03-01 19:15 ` [Qemu-devel] [PATCH v3 2/7] block/dirty-bitmap: add inconsistent status John Snow
2019-03-06 13:05   ` Vladimir Sementsov-Ogievskiy
2019-03-06 15:14     ` John Snow
2019-03-01 19:15 ` [Qemu-devel] [PATCH v3 3/7] block/dirty-bitmaps: add block_dirty_bitmap_check function John Snow
2019-03-01 19:36   ` Eric Blake
2019-03-01 19:57     ` John Snow
2019-03-01 20:03       ` Eric Blake
2019-03-01 20:06         ` Eric Blake
2019-03-06 13:44   ` Vladimir Sementsov-Ogievskiy
2019-03-06 15:17     ` John Snow
2019-03-01 19:15 ` [Qemu-devel] [PATCH v3 4/7] block/dirty-bitmaps: prohibit readonly bitmaps for backups John Snow
2019-03-01 19:38   ` Eric Blake
2019-03-06 13:47   ` Vladimir Sementsov-Ogievskiy
2019-03-01 19:15 ` [Qemu-devel] [PATCH v3 5/7] block/dirty-bitmaps: prohibit removing readonly bitmaps John Snow
2019-03-01 19:39   ` Eric Blake
2019-03-06 13:49   ` Vladimir Sementsov-Ogievskiy
2019-03-01 19:15 ` [Qemu-devel] [PATCH v3 6/7] block/dirty-bitmaps: disallow busy bitmaps as merge source John Snow
2019-03-01 19:44   ` Eric Blake
2019-03-01 19:48     ` John Snow
2019-03-01 19:57       ` Eric Blake
2019-03-01 20:04         ` John Snow
2019-03-06 13:57           ` Vladimir Sementsov-Ogievskiy
2019-03-06 15:24             ` John Snow
2019-03-06 15:29               ` Eric Blake [this message]
2019-03-06 13:57   ` Vladimir Sementsov-Ogievskiy
2019-03-01 19:15 ` [Qemu-devel] [PATCH v3 7/7] block/dirty-bitmaps: implement inconsistent bit John Snow
2019-03-01 19:53   ` Eric Blake
2019-03-06 14:26   ` Vladimir Sementsov-Ogievskiy
2019-03-06 21:46     ` John Snow
2019-03-07 16:37       ` Eric Blake
2019-03-08 18:46         ` John Snow
2019-03-05 23:59 ` [Qemu-devel] [PATCH v3 0/7] bitmaps: add " John Snow

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