Hello,
To reproduce...
*) in one terminal window:
btrfs sub create test
chattr +C test
cd test/
while true; do dd if=/dev/zero of=zerofile bs=1M count=1024; sync; done
*) in another terminal window start repeatedly snapshotting 'test', at random
1-3-5 second intervals:
mkdir snaps
btrfs sub snap test snaps/test-`date +%Y-%m-%dT%H:%M:%S`
The 'dd' output of first window then looks like this for me:
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 0.49982 s, 2.1 GB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 0.541291 s, 2.0 GB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 4.88021 s, 220 MB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 4.56427 s, 235 MB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 0.530991 s, 2.0 GB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 5.68497 s, 189 MB/s
dd: writing `zerofile': No space left on device
1+0 records in
0+0 records out
0 bytes (0 B) copied, 0.000591943 s, 0.0 kB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 4.25015 s, 253 MB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 4.66459 s, 230 MB/s
dd: writing `zerofile': No space left on device
1015+0 records in
1014+0 records out
1063489536 bytes (1.1 GB) copied, 3.0433 s, 349 MB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 4.24264 s, 253 MB/s
dd: writing `zerofile': No space left on device
1+0 records in
0+0 records out
0 bytes (0 B) copied, 0.000647234 s, 0.0 kB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 3.56673 s, 301 MB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 3.71281 s, 289 MB/s
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 0.551317 s, 1.9 GB/s
^C
-----
This also causes my KVM VMs to fail with a high probability during
snapshotting of their backing subvolume (as described in the previous thread).
--
With respect,
Roman
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