On Tue, Sep 26, 2017 at 1:45 PM, Xiao Yang <yangx.jy@xxxxxxxxxxxxxx> wrote: > On 2017/09/25 18:53, Amir Goldstein wrote: >> >> On Mon, Sep 25, 2017 at 12:49 PM, Xiao Yang<yangx.jy@xxxxxxxxxxxxxx> >> wrote: >>> >>> On 2017/08/27 18:44, Amir Goldstein wrote: >>>> >>>> This test is motivated by a bug found in ext4 during random crash >>>> consistency tests. >>>> >>>> This test uses device mapper flakey target to demonstrate the bug >>>> found using device mapper log-writes target. >>>> >>>> Signed-off-by: Amir Goldstein<amir73il@xxxxxxxxx> >>>> --- >>>> >>>> Ted, >>>> >>>> While working on crash consistency xfstests [1], I stubmled on what >>>> appeared to be an ext4 crash consistency bug. >>>> >>>> The tests I used rely on the log-writes dm target code written >>>> by Josef Bacik, which had little exposure to the wide community >>>> as far as I know. I wanted to prove to myself that the found >>>> inconsistency was not due to a test bug, so I bisected the failed >>>> test to the minimal operations that trigger the failure and wrote >>>> a small independent test to reproduce the issue using dm flakey target. >>>> >>>> The following fsck error is reliably reproduced by replaying some fsx >>>> ops >>>> on overlapping file regions, then emulating a crash, followed by mount, >>>> umount and fsck -nf: >>>> >>>> ./ltp/fsx -d --replay-ops /tmp/8995.fsxops /mnt/scratch/testfile >>>> 1 write 0x137dd thru 0x21445 (0xdc69 bytes) >>>> 2 falloc from 0xb531 to 0x16ade (0xb5ad bytes) >>>> 3 collapse from 0x1c000 to 0x20000, (0x4000 bytes) >>>> 4 write 0x3e5ec thru 0x3ffff (0x1a14 bytes) >>>> 5 zero from 0x20fac to 0x27d48, (0x6d9c bytes) >>>> 6 mapwrite 0x216ad thru 0x23dfb (0x274f bytes) >>>> All 7 operations completed A-OK! >>>> _check_generic_filesystem: filesystem on /dev/mapper/ssd-scratch is >>>> inconsistent >>>> *** fsck.ext4 output *** >>>> fsck from util-linux 2.27.1 >>>> e2fsck 1.42.13 (17-May-2015) >>>> Pass 1: Checking inodes, blocks, and sizes >>>> Inode 12, end of extent exceeds allowed value >>>> (logical block 33, physical block 33441, len 7) >>>> Clear? no >>>> Inode 12, i_blocks is 184, should be 128. Fix? no >>> >>> Hi Amir, >>> >>> I always get the following output when running your xfstests test case >>> 501. >> >> Now merged as test generic/456 >> >>> >>> --------------------------------------------------------------------------- >>> e2fsck 1.42.9 (28-Dec-2013) >>> Pass 1: Checking inodes, blocks, and sizes >>> Inode 12, i_size is 147456, should be 163840. Fix? no >>> >>> --------------------------------------------------------------------------- >>> >>> Could you tell me how to get the expected output as you reported? >> >> I can't say I am doing anything special, but I can say that I get the >> same output as you did when running the test inside kvm-xfstests. >> Actually, I could not reproduce ANY of the the crash consistency bugs >> inside kvm-xfstests. Must be something to do with different timing of >> IO with KVM+virtio disks?? >> >> When running on my laptop (Ubuntu 16.04 with latest kernel) >> on a 10G SSD volume, I always get the error reported above. >> I just re-verified with latest stable e2fsprogs (1.43.6). > > Hi Amir, > > I tested generic/456 with KVM+virtio disks and SATA volumes on some kernels I don't understand. Did you also test without KVM? Otherwise I suggest that you test without KVM/virtio. > (including > v3.10.0, the latest kernel), but i still got the same output as i reported. > > Could you determine whether the two different outputs are caused by the same > bug > or not ? No idea if those are 2 symptoms of the same bug or 2 different bugs I did not investigate the root cause. Amir.
