From: Paolo Bonzini <pbonzini@redhat.com>
To: famz@redhat.com
Cc: kwolf@redhat.com, rjones@redhat.com, obarenbo@redhat.com,
roliveri@redhat.com, hbrock@redhat.com, armbru@redhat.com,
qemu-devel@nongnu.org, pmyers@redhat.com, imain@redhat.com,
stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH 3/7] nbd: use BDS refcount
Date: Wed, 03 Jul 2013 07:58:13 +0200 [thread overview]
Message-ID: <51D3BD75.4030408@redhat.com> (raw)
In-Reply-To: <20130703011009.GE1949@t430s.nay.redhat.com>
Il 03/07/2013 03:10, Fam Zheng ha scritto:
> > This has the important side effect of marking the exported disk as
> > "in_use" (to use the terms before the series). Right now you can serve
> > a disk and, at the same time, stream it or mirror it or create a live
> > snapshot of it.
> >
> > Do we really want to block anything for a device being served? Perhaps
> > truncation, but maybe not even that. The NBD server is meant to be as
> > unobtrusive as possible (in some sense NBD accesses are the same as
> > guest accesses).
>
> OK, it is better to work like that. But I don't quite understand why was
> there drive_get_ref() on the device (w/o the series), as there's already
> a close notifier? And it just drive_put_ref() when bs is closed?
The close notifier runs when the user invokes a drive_del or eject
command from the monitor. The drive_get_ref/drive_put_ref delays the
bdrv_delete until after nbd.c has cleaned up all the connections.
Paolo
next prev parent reply other threads:[~2013-07-03 5:58 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-02 5:59 [Qemu-devel] [PATCH 0/7] Point-in-time snapshot exporting over NBD Fam Zheng
2013-07-02 5:59 ` [Qemu-devel] [PATCH 1/7] block: Convert BlockDriverState.in_use to refcount Fam Zheng
2013-07-02 10:21 ` Paolo Bonzini
2013-07-08 8:37 ` Fam Zheng
2013-07-02 19:41 ` Eric Blake
2013-07-03 0:59 ` Fam Zheng
2013-07-02 5:59 ` [Qemu-devel] [PATCH 2/7] block: use refcount to manage BlockDriverState lifecycle Fam Zheng
2013-07-02 5:59 ` [Qemu-devel] [PATCH 3/7] nbd: use BDS refcount Fam Zheng
2013-07-02 10:16 ` Paolo Bonzini
2013-07-03 1:10 ` Fam Zheng
2013-07-03 5:58 ` Paolo Bonzini [this message]
2013-07-03 6:30 ` Fam Zheng
2013-07-03 7:28 ` Paolo Bonzini
2013-07-02 5:59 ` [Qemu-devel] [PATCH 4/7] block: simplify bdrv_drop_intermediate Fam Zheng
2013-07-04 14:02 ` Stefan Hajnoczi
2013-07-05 1:00 ` Fam Zheng
2013-07-02 5:59 ` [Qemu-devel] [PATCH 5/7] block: rename bdrv_in_use to bdrv_is_shared Fam Zheng
2013-07-02 5:59 ` [Qemu-devel] [PATCH 6/7] block: add target-id option to drive-backup QMP command Fam Zheng
2013-07-02 19:59 ` Eric Blake
2013-07-02 5:59 ` [Qemu-devel] [PATCH 7/7] block: assign backing relationship in drive-backup Fam Zheng
2013-07-04 14:32 ` Stefan Hajnoczi
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