From: Fam Zheng <famz@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, pl@kamp.de,
pbonzini@redhat.com, ronniesahlberg@gmail.com,
stefanha@redhat.com, mreitz@redhat.com, kwolf@redhat.com,
jcody@redhat.com, jsnow@redhat.com, den@openvz.org
Subject: Re: [Qemu-devel] [PATCH v5 1/4] block/io: fix copy_range
Date: Tue, 10 Jul 2018 09:49:35 +0800 [thread overview]
Message-ID: <20180710014935.GF17581@lemon.usersys.redhat.com> (raw)
In-Reply-To: <20180709163719.87107-2-vsementsov@virtuozzo.com>
On Mon, 07/09 19:37, Vladimir Sementsov-Ogievskiy wrote:
> Here two things are fixed:
>
> 1. Architecture
>
> On each recursion step, we go to the child of src or dst, only for one
> of them. So, it's wrong to create tracked requests for both on each
> step. It leads to tracked requests duplication.
>
> 2. Wait for serializing requests on write path independently of
> BDRV_REQ_NO_SERIALISING
>
> Before commit 9ded4a01149 "backup: Use copy offloading",
> BDRV_REQ_NO_SERIALISING was used for only one case: read in
> copy-on-write operation during backup. Also, the flag was handled only
> on read path (in bdrv_co_preadv and bdrv_aligned_preadv).
>
> After 9ded4a01149, flag is used for not waiting serializing operations
> on backup target (in same case of copy-on-write operation). This
> behavior change is unsubstantiated and potentially dangerous, let's
> drop it and add additional asserts and documentation.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
next prev parent reply other threads:[~2018-07-10 1:49 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-09 16:37 [Qemu-devel] [PATCH v5 0/4] fix image fleecing Vladimir Sementsov-Ogievskiy
2018-07-09 16:37 ` [Qemu-devel] [PATCH v5 1/4] block/io: fix copy_range Vladimir Sementsov-Ogievskiy
2018-07-10 1:49 ` Fam Zheng [this message]
2018-07-09 16:37 ` [Qemu-devel] [PATCH v5 2/4] block: split flags in copy_range Vladimir Sementsov-Ogievskiy
2018-07-10 1:52 ` Fam Zheng
2018-07-09 16:37 ` [Qemu-devel] [PATCH v5 3/4] block: add BDRV_REQ_SERIALISING flag Vladimir Sementsov-Ogievskiy
2018-07-10 2:51 ` Fam Zheng
2018-07-09 16:37 ` [Qemu-devel] [PATCH v5 4/4] block/backup: fix fleecing scheme: use serialized writes Vladimir Sementsov-Ogievskiy
2018-07-10 2:57 ` Fam Zheng
2018-07-10 11:13 ` [Qemu-devel] [PATCH v5 0/4] fix image fleecing Kevin Wolf
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