From: Max Reitz <mreitz@redhat.com>
To: Alberto Garcia <berto@igalia.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Nir Soffer <nsoffer@redhat.com>,
qemu-block@nongnu.org
Subject: Re: [PATCH v2 1/4] qcow2: Require that the virtual size is a multiple of the sector size
Date: Tue, 14 Jan 2020 14:01:03 +0100 [thread overview]
Message-ID: <bd6ca991-c2f7-0e27-5bee-07a7c53f8a8e@redhat.com> (raw)
In-Reply-To: <6a1cfcbb533b487bac96e1d2282ebf210954d27a.1578596897.git.berto@igalia.com>
[-- Attachment #1.1: Type: text/plain, Size: 828 bytes --]
On 09.01.20 20:12, Alberto Garcia wrote:
> The qcow2 header specifies the virtual size of the image in bytes, but
> BlockDriverState stores it as a number of 512-byte sectors.
>
> If the user tries to create an image with a size that is not a
> multiple of the sector size then this is fixed on creation by
> silently rounding the image size up (see commit c2eb918e32).
> qcow2_co_truncate() is more strict and returns an error instead.
>
> However when an image is opened the virtual size is rounded down,
> which means that trying to access the last few advertised bytes will
> result in an error. As seen above QEMU cannot create such images and
> there's no good use case that would require us to try to handle them
> so let's just treat them as unsupported.
But isn’t that just a bug in qemu?
Max
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
next prev parent reply other threads:[~2020-01-14 13:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-09 19:12 [PATCH v2 0/4] qcow2: Misc BDRV_SECTOR_SIZE updates Alberto Garcia
2020-01-09 19:12 ` [PATCH v2 1/4] qcow2: Require that the virtual size is a multiple of the sector size Alberto Garcia
2020-01-14 13:01 ` Max Reitz [this message]
2020-01-14 13:20 ` Alberto Garcia
2020-01-14 13:47 ` Max Reitz
2020-01-14 13:58 ` Alberto Garcia
2020-01-14 14:03 ` Max Reitz
2020-01-16 14:24 ` Alberto Garcia
2020-01-09 19:13 ` [PATCH v2 2/4] qcow2: Don't round the L1 table allocation up to " Alberto Garcia
2020-01-14 13:46 ` Max Reitz
2020-01-09 19:13 ` [PATCH v2 3/4] qcow2: Tighten cluster_offset alignment assertions Alberto Garcia
2020-01-10 12:14 ` Alberto Garcia
2020-01-14 13:58 ` Max Reitz
2020-01-14 13:56 ` Max Reitz
2020-01-09 19:13 ` [PATCH v2 4/4] qcow2: Use BDRV_SECTOR_SIZE instead of the hardcoded value Alberto Garcia
2020-01-14 14:15 ` Max Reitz
2020-01-16 23:26 ` Alberto Garcia
2020-01-17 9:12 ` Max Reitz
2020-01-17 9:55 ` Kevin Wolf
2020-01-17 11:01 ` Max Reitz
2020-01-17 11:51 ` Kevin Wolf
2020-01-17 14:34 ` Alberto Garcia
2020-01-18 18:07 ` Alberto Garcia
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=bd6ca991-c2f7-0e27-5bee-07a7c53f8a8e@redhat.com \
--to=mreitz@redhat.com \
--cc=berto@igalia.com \
--cc=kwolf@redhat.com \
--cc=nsoffer@redhat.com \
--cc=qemu-block@nongnu.org \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).