[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
request_alignment vs file size, how to fix crash?
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
request_alignment vs file size, how to fix crash? |
Date: |
Wed, 29 Jan 2020 18:01:31 +0000 |
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
- request_alignment vs file size, how to fix crash?,
Vladimir Sementsov-Ogievskiy <=