We've had a report of the BUG in md_write_start() being triggered while
running the Debian installer: <http://bugs.debian.org/696650>.
Based on the call trace, I came up with the following script that
reproduces this under Linux 3.2.35 and 3.7.3:
--- BEGIN ---
#!/bin/bash -ex
# Set up temporary RAID1 on /dev/md0
dd if=/dev/zero of=/tmp/disk0 bs=1M count=1
losetup /dev/loop0 /tmp/disk0
dd if=/dev/zero of=/tmp/disk1 bs=1M count=1
losetup /dev/loop1 /tmp/disk1
yes | mdadm -C /dev/md0 -l 1 -n 2 /dev/loop{0,1}
# Make it read-only
while ! mdadm -o /dev/md0; do sleep 1; done
# Call fsync()
python -c "import os; os.fsync(os.open('/dev/md0', os.O_RDWR))"
--- END ---
I assume that the sync request should be filtered out at some point
before this assertion is made, since there can be nothing to sync.
Ben.
--
Ben Hutchings
Never attribute to conspiracy what can adequately be explained by stupidity.
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