On Sun, Aug 27, 2017 at 1:21 PM, Amir Goldstein <amir73il@xxxxxxxxx> 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 3 fsx ops > (write, zero_range, mapwrite) on overlapping regions, then > emulating a crash, followed by mount and umount: > > ./ltp/fsx -d --replay-ops /tmp/8995.fsxops /mnt/scratch/testfile > 1 write 0x3e5ec thru 0x3ffff (0x1a14 bytes) > 2 zero from 0x20fac to 0x27d48, (0x6d9c bytes) > 3 mapwrite 0x216ad thru 0x23dfb (0x274f bytes) > All 4 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, i_size is 147456, should be 163840. Fix? no > Sorry, I wanted to report a different (additional) error - re-sending..
