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From: "Benoît Canet" <benoit.canet@gmail.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: kwolf@redhat.com, pbonzini@redhat.com,
	Anthony Liguori <aliguori@us.ibm.com>,
	qemu-devel@nongnu.org, stefanha@linux.vnet.ibm.com
Subject: Re: [Qemu-devel] [PATCH V2 4/7] qed: add bdrv_invalidate_cache to be called after incoming live migration
Date: Thu, 22 Mar 2012 15:15:01 +0100	[thread overview]
Message-ID: <CAOh3yay__9FmsxjvX8h-mHTPMbMkK459W31eyzU_08Qn=PUz3Q@mail.gmail.com> (raw)
In-Reply-To: <CAJSP0QWWmKBjTYeL3x2YH6T5-gswjE-4C6709b4b_BM6brwt0g@mail.gmail.com>

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>It's not clear to me why we need to introduce this field to stash
>flags values.  bs->open_flags already has this information.

>Originally this was introduced in 06d9260ffa9 ("qcow2: implement
>bdrv_invalidate_cache (v2)") for qcow2.  I wonder if that field is
>necessary when we already have bs->open_flags.

>What I don't like about s->flags is that it duplicates state *and*
>it's done in each block driver that supports .bdrv_invalidate_cache().
> So I wonder if we can drop it?

I added this flag after seeing the following code in in bdrv_open_common.

    /*
     * Clear flags that are internal to the block layer before opening the
     * image.
     */
    open_flags = flags & ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);

This lead me to believe that  bs->open_flags != open_flags.

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  reply	other threads:[~2012-03-22 14:15 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-21 15:51 [Qemu-devel] [PATCH V2 0/7] Make QED with live migration safe Benoît Canet
2012-03-21 15:51 ` [Qemu-devel] [PATCH V2 1/7] block: Add new BDRV_O_INCOMING flag to notice incoming live migration Benoît Canet
2012-03-21 15:51 ` [Qemu-devel] [PATCH V2 2/7] block: add a function to clear incoming live migration flags Benoît Canet
2012-03-21 15:52 ` [Qemu-devel] [PATCH V2 3/7] blockdev: open images with BDRV_O_INCOMING on incoming live migration Benoît Canet
2012-03-21 15:52 ` [Qemu-devel] [PATCH V2 4/7] qed: add bdrv_invalidate_cache to be called after " Benoît Canet
2012-03-22 13:21   ` Stefan Hajnoczi
2012-03-22 14:15     ` Benoît Canet [this message]
2012-03-22 14:17       ` Paolo Bonzini
2012-03-22 15:30         ` Stefan Hajnoczi
2012-03-21 15:52 ` [Qemu-devel] [PATCH V2 5/7] migration: clear BDRV_O_INCOMING flags on end of " Benoît Canet
2012-03-21 15:52 ` [Qemu-devel] [PATCH V2 6/7] qed: honor BDRV_O_INCOMING for " Benoît Canet
2012-03-21 15:52 ` [Qemu-devel] [PATCH V2 7/7] qed: remove incoming live migration blocker Benoît Canet

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