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Date: Thu, 16 Jan 2014 10:39:30 +0100
From: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20140116093930.GA3369@dhcp-200-207.str.redhat.com>
References: <2fb3ea05d2e1ee06d578a0f2c53f56df1661401c.1389726691.git.jcody@redhat.com>
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In-Reply-To: <2fb3ea05d2e1ee06d578a0f2c53f56df1661401c.1389726691.git.jcody@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] block: do not allow read-only=on and
 snapshot=on to be used together
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To: Jeff Cody <jcody@redhat.com>
Cc: pbonzini@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com

Am 14.01.2014 um 20:12 hat Jeff Cody geschrieben:
> Having both read-only=on and snapshot=on together does not make sense;
> currently, the read-only argument is effectively ignored for the
> temporary snapshot.  To prevent confusion, disallow the usage of both
> 'snapshot=on' and 'read-only=on'.
> 
> Signed-off-by: Jeff Cody <jcody@redhat.com>

I believe the reason why this was allowed was so that you can use a
read-only file with -snapshot. It might not be necessary any more since
I switched -snapshot implementation to modify the options QDict instead
of manually doing a second bdrv_open().

Did you test that this still works now?

The other question is about this code in bdrv_open_flags():

    /*
     * Snapshots should be writable.
     */
    if (bs->is_temporary) {
        open_flags |= BDRV_O_RDWR;
    }

Is this dead code now because the flag is always already set?

Kevin