On Thu, Sep 29, 2016 at 03:54:14PM +0800, Eryu Guan wrote:
> On Tue, Aug 30, 2016 at 12:39:05PM +1000, Dave Chinner wrote:
> > On Mon, Aug 29, 2016 at 06:37:54PM +0800, Eryu Guan wrote:
> > > Hi,
> > >
> > > I've hit an XFS internal error then filesystem shutdown with 4.8-rc3
> > > kernel but not with 4.8-rc2
> > .....
> > > I attached a script too to reproduce it. Please note that the XFS
> > > partition needs about 40G frees space, and it may take hours to finish
> > > based on your memory setup on your host.
> >
> > Ugh. can you try to narrow the cause so it takes less time to
> > reproduce? This is almost certainly one of two things:
> >
> > 1) a ENOSPC issue where an AG is almost-but-not-quite full,
> > but fixing up the freelist results in there being not enough
> > blocks left to allocate the data extent; or
> >
> > 2) we've split a delalloc extent so many times that we've
> > run out of indirect block reservation and we hit ENOSPC as a
> > result.
>
> [Sorry for getting back on this after so long time..]
>
> >
> > For the latter, I suspect a test case where we take a large delalloc
> > range and use sync_file_range to do single page writeback to "binary
> > split" the delalloc range. i.e. start with a 128MB delalloc, then
> > sync a 4k block at offset 64MB, then 4k at 32MB, then 16MB, then
> > 8MB, ... all the way down to writing the first block in the file,
> > and also all the way up to the final block in the file.
> >
> > Then write every second 4k block to cause worse case growth of the
> > bmbt and hopefully then exhaust the indirect block reservation for
> > that delalloc region...
>
> Seems it's only reproducible on certain hosts, and I haven't been able
> to work out an efficient & reliable reproducer. I tried to tuned the
> parameters of bash-shared-mapping run, but failed to find a efficient
> parameter conbination. Also tried to write a script (attached, not sure
> if it's correct) based on the second case above, but still cannot
> reproduce it.
Test script:
#!/bin/bash
dev=/dev/mapper/systemvg-lv50g
mnt=/mnt/xfs
testfile=/mnt/xfs/testfile
umount $dev
mount $dev $mnt
rm -f $testfile.*
do_test()
{
local testfile=$1
echo "pwrite -b 128M 0 128M && sync_range 64M 4k"
#xfs_io -fc "falloc 0 128M" -c "sync_range 64M 4k" $testfile >/dev/null
#xfs_io -fc "pwrite $((128*1024*1024 - 4096)) 4096" -c "sync_range 64M 4k" $testfile >/dev/null
xfs_io -fc "pwrite -b 128M 0 128M" -c "sync_range 64M 4k" $testfile >/dev/null
step=33554432 # 32M
off_down=67108864 # 64M
off_up=67108864 # 64M
while [ $off_down -gt 0 ]; do
if [ $step -lt 4096 ]; then
step=4096
fi
off_down=$((off_down - step))
off_up=$((off_up + step))
step=$((step / 2))
echo "sync_range $off_down 4k && sync_range $off_up 4k"
xfs_io -c "sync_range $off_down 4k" -c "sync_range $off_up 4k" $testfile
done
offset=4096
while [ $offset -lt 134217728 ]; do
# echo "pwrite $offset 4k"
xfs_io -c "pwrite $offset 4k" $testfile >/dev/null
offset=$((offset + 8192))
done
}
for i in `seq 1 10`; do
do_test $testfile.$i &
done
wait
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