Comment 1 for bug 1424114

I have seen a similar issue with Ubuntu 14.10

Repro steps:

root@ubuntu-amd64:~# lsb_release -cd
Description: Ubuntu 14.10
Codename: utopic

# after reboot
root@ubuntu-amd64:~# cat /etc/lvm/lvm.conf | grep " snapshot_autoextend"
    snapshot_autoextend_threshold = 80
    snapshot_autoextend_percent = 20

root@ubuntu-amd64:~# vgs
  VG #PV #LV #SN Attr VSize VFree
  vg1 1 0 0 wz--n- 20.00g 20.00g

root@ubuntu-amd64:~# lvcreate -n vol1 -L 100MB vg1
  Logical volume "vol1" created
root@ubuntu-amd64:~# lvs
  LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
  vol1 vg1 -wi-a---- 100.00m

root@ubuntu-amd64:~# lvs
  LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
  snap1 vg1 swi-a-s-- 12.00m vol1 0.00
  vol1 vg1 owi-a-s-- 100.00m

root@ubuntu-amd64:~# dd if=/dev/zero of=/dev/vg1/vol1 count=11 bs=1MB
11+0 records in
11+0 records out
11000000 bytes (11 MB) copied, 0.087546 s, 126 MB/s
root@ubuntu-amd64:~# lvs
  LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
  snap1 vg1 swi-a-s-- 12.00m vol1 87.83
  vol1 vg1 owi-a-s-- 100.00m

At this point I expected the snap1 volume to be auto extended based on the 80% setting in lvm.conf. However as can be seen the snapshot is 87% and the size stays as 12MB. If I continue writing the snapshot gets fill and disabled.