xlog_space_left: head behind tail

[Jan Kara]

  Hello,

  when I run:
while true; do ~/tests/xfstests-dev/ltp/fsstress -d /mnt -n 10000 -p 4; done

and in parallel

while true; do ./fsfreeze /mnt; sync; ./fsfreeze -u /mnt; sleep 3; done

where fsfreeze is a small utility freezing and unfreezing filesystem. I get
warnings like:
[ 2029.103193] XFS (vdb1): xlog_space_left: head behind tail
[ 2029.103195]   tail_cycle = 10, tail_bytes = 6036480
[ 2029.103197]   GH   cycle = 10, GH   bytes = 6035728
[ 2029.103218] XFS (vdb1): xlog_space_left: head behind tail
[ 2029.103219]   tail_cycle = 10, tail_bytes = 6036480
[ 2029.103220]   GH   cycle = 10, GH   bytes = 6035728
[ 2033.269796] XFS (vdb1): xlog_space_left: head behind tail
[ 2033.269800]   tail_cycle = 10, tail_bytes = 6400512
[ 2033.269803]   GH   cycle = 10, GH   bytes = 6399752
[ 2033.269830] XFS (vdb1): xlog_space_left: head behind tail
[ 2033.269835]   tail_cycle = 10, tail_bytes = 6400512
[ 2033.269838]   GH   cycle = 10, GH   bytes = 6399752
[ 2033.269847] XFS (vdb1): xlog_space_left: head behind tail
[ 2033.269850]   tail_cycle = 10, tail_bytes = 6400512
[ 2033.269852]   GH   cycle = 10, GH   bytes = 6399752
[ 2033.269892] XFS (vdb1): xlog_space_left: head behind tail
[ 2033.269894]   tail_cycle = 10, tail_bytes = 6400512
[ 2033.269896]   GH   cycle = 10, GH   bytes = 6399752
[ 2033.269915] XFS (vdb1): xlog_space_left: head behind tail
[ 2033.269918]   tail_cycle = 10, tail_bytes = 6400512
[ 2033.269920]   GH   cycle = 10, GH   bytes = 6399752

They usually start to appear like 20 minutes after starting the tests and
when they start to appear they happen every couple of seconds (as you can
see from the timestamps). Is it a real problem or just annoyance?

								Honza
-- 
Jan Kara <jack at suse.cz>
SUSE Labs, CR