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From: Kevin Wolf <kwolf@redhat.com>
To: "Denis V. Lunev" <den@openvz.org>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 4/5] qcow2: fix condition in is_zero_cluster
Date: Tue, 17 May 2016 17:11:05 +0200	[thread overview]
Message-ID: <20160517151105.GD9802@noname.redhat.com> (raw)
In-Reply-To: <1463476543-3087-5-git-send-email-den@openvz.org>

Am 17.05.2016 um 11:15 hat Denis V. Lunev geschrieben:
> We should check for (res & BDRV_BLOCK_ZERO) only. The situation when we
> will have !(res & BDRV_BLOCK_DATA) and will not have BDRV_BLOCK_ZERO is
> not possible.

The patch is okay, but I'm correcting this paragraph into:

    We should check for (res & BDRV_BLOCK_ZERO) only. The situation when we
    will have !(res & BDRV_BLOCK_DATA) and will not have BDRV_BLOCK_ZERO is
    not possible for images with bdi.unallocated_blocks_are_zero == true.

    For those images where it's false, however, it can happen and we must
    not consider the data zeroed then or we would corrupt the image.

Kevin

  reply	other threads:[~2016-05-17 15:11 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-17  9:15 [Qemu-devel] [PATCH v2 0/5] qcow2_co_write_zeroes and related improvements Denis V. Lunev
2016-05-17  9:15 ` [Qemu-devel] [PATCH 1/5] block: split write_zeroes always Denis V. Lunev
2016-05-17 16:34   ` Kevin Wolf
2016-05-25 18:36     ` Eric Blake
2016-05-17  9:15 ` [Qemu-devel] [PATCH 2/5] qcow2: simplify logic in qcow2_co_write_zeroes Denis V. Lunev
2016-05-17  9:15 ` [Qemu-devel] [PATCH 3/5] qcow2: add tracepoints for qcow2_co_write_zeroes Denis V. Lunev
2016-05-17 15:37   ` Eric Blake
2016-05-17  9:15 ` [Qemu-devel] [PATCH 4/5] qcow2: fix condition in is_zero_cluster Denis V. Lunev
2016-05-17 15:11   ` Kevin Wolf [this message]
2016-05-17  9:15 ` [Qemu-devel] [PATCH 5/5] qcow2: merge is_zero_cluster helpers into qcow2_co_write_zeroes Denis V. Lunev
2016-05-24 18:14   ` Eric Blake
2016-05-17 15:11 ` [Qemu-devel] [PATCH v2 0/5] qcow2_co_write_zeroes and related improvements Kevin Wolf

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