From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu block <qemu-block@nongnu.org>
Cc: Kevin Wolf <kwolf@redhat.com>, Denis Lunev <den@virtuozzo.com>,
qemu-devel <qemu-devel@nongnu.org>, Max Reitz <mreitz@redhat.com>
Subject: request_alignment vs file size, how to fix crash?
Date: Wed, 29 Jan 2020 18:01:31 +0000 [thread overview]
Message-ID: <2ca46523-44a2-1a48-dfa3-11bda9eef8e8@virtuozzo.com> (raw)
Hi!
I found a crash, which may be simply triggered for images unaligned to request_alignment:
# ./qemu-io --image-opts -c 'write 0 512' driver=blkdebug,align=4096,image.driver=null-co,image.size=512
qemu-io: block/io.c:1505: bdrv_aligned_pwritev: Assertion `end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE' failed.
Aborted (core dumped)
The problem is obvious: 512 is aligned to 4096 and becomes larger than file size.
I faced it after rebasing our downstream branches to newer Rhel versions. Seems that after some updates of alignment detection in file-posix.c, it started to detect 4096 alignment in our build environment, and iotest 152 started to crash (as it operates on file of 512 bytes).
My question is:
What is wrong? Should we restrict images to be aligned to request_alignment, or allow unaligned operations at EOF, if file is unaligned itself?
--
Best regards,
Vladimir
next reply other threads:[~2020-01-29 18:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 18:01 Vladimir Sementsov-Ogievskiy [this message]
2020-01-30 10:40 ` request_alignment vs file size, how to fix crash? Vladimir Sementsov-Ogievskiy
2020-01-30 11:11 ` Kevin Wolf
2020-01-30 11:30 ` Vladimir Sementsov-Ogievskiy
2020-01-30 12:12 ` Kevin Wolf
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