From: Kevin Wolf <kwolf@redhat.com>
To: Zhe Qiu <phoeagon@gmail.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v3] block/vdi: Use bdrv_flush after metadata updates
Date: Fri, 8 May 2015 12:43:37 +0200 [thread overview]
Message-ID: <20150508104337.GE4318@noname.redhat.com> (raw)
In-Reply-To: <1430971496-32659-1-git-send-email-phoeagon@gmail.com>
Am 07.05.2015 um 06:04 hat Zhe Qiu geschrieben:
> From: phoeagon <phoeagon@gmail.com>
>
> In reference to b0ad5a455d7e5352d4c86ba945112011dbeadfb8~078a458e077d6b0db262c4b05fee51d01de2d1d2, metadata writes to qcow2/cow/qcow/vpc/vmdk are all synced prior to succeeding writes.
The justification for these patches (in 2010!) was more or less that we
didn't know whether the implementations were safe without the flushes.
Many of the flushes added back then have been removed again until today
because they have turned out to be unnecessary.
> Only when write is successful that bdrv_flush is called.
>
> Signed-off-by: Zhe Qiu <phoeagon@gmail.com>
Please describe why VDI needs this flush to be safe. This is best done
by describing a case where not doing the flush would lead to image
corruption in case of a crash.
To my knowledge, the VDI driver is completely safe without it.
Kevin
next prev parent reply other threads:[~2015-05-08 10:43 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-07 4:04 [Qemu-devel] [PATCH v3] block/vdi: Use bdrv_flush after metadata updates Zhe Qiu
2015-05-07 10:09 ` Stefan Hajnoczi
2015-05-07 15:05 ` [Qemu-devel] [Qemu-block] " Eric Blake
2015-05-07 15:16 ` [Qemu-devel] [PATCH v4] " Zhe Qiu
2015-05-08 13:14 ` Max Reitz
2015-05-08 13:55 ` Kevin Wolf
2015-05-08 14:43 ` phoeagon
2015-05-08 21:26 ` Stefan Weil
2015-05-09 3:54 ` phoeagon
2015-05-09 3:59 ` phoeagon
2015-05-09 6:39 ` Stefan Weil
2015-05-09 7:41 ` phoeagon
2015-05-10 15:01 ` Paolo Bonzini
2015-05-10 16:02 ` Stefan Weil
2015-05-10 16:05 ` phoeagon
2015-05-10 16:10 ` Paolo Bonzini
2015-05-10 16:26 ` Stefan Weil
2015-05-10 17:14 ` phoeagon
2015-05-08 10:43 ` Kevin Wolf [this message]
2015-05-08 11:50 ` [Qemu-devel] [Qemu-block] [PATCH v3] " phoeagon
2015-05-08 12:02 ` Kevin Wolf
2015-05-08 12:56 ` phoeagon
2015-05-08 13:10 ` [Qemu-devel] " Max Reitz
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