From: Konstantin Khorenko <khorenko@virtuozzo.com>
To: Alexander Ivanov <alexander.ivanov@virtuozzo.com>,
andrey.zhadchenko@virtuozzo.com
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 0/3] dm-qcow2: keep images of a read-only table unmodified
Date: Thu, 29 Oct 2026 12:42:07 +0100 [thread overview]
Message-ID: <5ef02a5b-bab9-40bb-8813-b3fdee7e4723@virtuozzo.com> (raw)
In-Reply-To: <20261023132008.2304901-1-alexander.ivanov@virtuozzo.com>
Three things found while reviewing the series, none of them for it.
Please fix them separately.
- A v3 image with header_length < 104 is not rejected. The only check
is header_length < sizeof(struct QCowHeader), and only when the
compression bit is set. qemu fails such an image with "qcow2 header
too short". For us the extension parser then starts inside the
header.
- For a v2 image hdr->header_length is never set, so it stays 0 from
kzalloc() and the extensions are parsed from offset 0 of the header
instead of 72. qemu sets header_length = 72 for v2.
- The table mode is still tested against FMODE_WRITE in
qcow2_check_convert_hdr(), qcow2_attach_file(),
qcow2_truncate_preallocations(), qcow2_postsuspend() and
qcow2_preresume(), while the series switched to BLK_OPEN_WRITE. Same
value today, but dm_table_get_mode() returns blk_mode_t. The is_ro
in qcow2_check_convert_hdr() has only a commented-out user and can go.
Please file appropriate tasks and fix them separately.
--
Best regards,
Konstantin Khorenko,
Virtuozzo Linux Kernel Team
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next prev parent reply other threads:[~2026-10-29 11:43 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-23 13:20 Alexander Ivanov
2026-10-23 13:20 ` [Devel] [PATCH hci-8.1 1/3] drivers/md/dm-qcow2: treat images of a read-only table as read-only Alexander Ivanov
2026-10-23 13:24 ` no-reply
2026-10-29 11:36 ` Konstantin Khorenko
2026-10-23 13:20 ` [Devel] [PATCH hci-8.1 2/3] drivers/md/dm-qcow2: fail writes to a read-only table Alexander Ivanov
2026-10-23 13:23 ` no-reply
2026-10-28 10:35 ` Andrey Zhadchenko
2026-10-23 13:20 ` [Devel] [PATCH hci-8.1 3/3] drivers/md/dm-qcow2: do not revalidate inconsistent persistent bitmaps Alexander Ivanov
2026-10-23 13:25 ` no-reply
2026-10-23 13:58 ` Alexander Ivanov
2026-10-29 11:39 ` Konstantin Khorenko
2026-10-28 10:47 ` [Devel] [PATCH hci-8.1 0/3] dm-qcow2: keep images of a read-only table unmodified Andrey Zhadchenko
2026-10-29 11:42 ` Konstantin Khorenko [this message]
2026-10-29 14:48 ` Alexander Ivanov
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