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From: Eric Blake <eblake@redhat.com>
To: Max Reitz <mreitz@redhat.com>, qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
	qemu-stable@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 0/2] block/file-posix: Fix fully preallocated truncate
Date: Wed, 28 Feb 2018 08:22:37 -0600	[thread overview]
Message-ID: <e5b4f75c-6dbf-c5cc-8463-f28bb48d3956@redhat.com> (raw)
In-Reply-To: <20180228131315.30194-1-mreitz@redhat.com>

On 02/28/2018 07:13 AM, Max Reitz wrote:
> Fully preallocated truncation has a 50 % chance of working on images
> files over file-posix.  It works if $SIZE % 4G < 2G, and it fails
> otherwise.  To make things even more interesting, often you would not
> even notice because qemu reported success even though it did nothing
> (because after the successful lseek(), errno was still 0, so when the
> file-posix driver tried to return a negative error code, it actually
> reported success).
> 
> This issue is fixed by patch 1 in this series.  Thanks to Daniel for
> reporting!
> 
> 
> Max Reitz (2):
>    block/file-posix: Fix fully preallocated truncate
>    iotests: Test preallocated truncate of 2G image

Good catch.  Series:
Reviewed-by: Eric Blake <eblake@redhat.com>

gluster.c has similar code, but it assigns glfs_lseek() to an int64_t, 
so it does not have the bug.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

  parent reply	other threads:[~2018-02-28 14:22 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-28 13:13 [Qemu-devel] [PATCH 0/2] block/file-posix: Fix fully preallocated truncate Max Reitz
2018-02-28 13:13 ` [Qemu-devel] [PATCH 1/2] " Max Reitz
2018-02-28 13:34   ` Daniel P. Berrangé
2018-02-28 13:45     ` Max Reitz
2018-02-28 13:53       ` Daniel P. Berrangé
2018-02-28 13:55         ` Max Reitz
2018-02-28 13:59           ` Daniel P. Berrangé
2018-02-28 14:20         ` Eric Blake
2018-02-28 13:58   ` Daniel P. Berrangé
2018-02-28 13:13 ` [Qemu-devel] [PATCH 2/2] iotests: Test preallocated truncate of 2G image Max Reitz
2018-02-28 14:02   ` Daniel P. Berrangé
2018-02-28 14:22 ` Eric Blake [this message]
2018-03-26 20:30 ` [Qemu-devel] [PATCH 0/2] block/file-posix: Fix fully preallocated truncate Max Reitz

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