Bug 471565

Description of problem:
Creation of a mirrored LV with disk log fails, if the VG extent-size is 1K (2K and bigger works as expected).


Version-Release number of selected component (if applicable):
$ lvm version
  LVM version:     2.02.32-RHEL5 (2008-03-04)
  Library version: 1.02.24 (2007-12-20)
  Driver version:  4.11.5 


How reproducible:
Create a volume group with extent size of 1K and a mirrored logical volume with a disk based mirror log.


Steps to Reproduce:
$ dd if=/dev/zero of=/test/image[1,2,3] bs=1024k count=128
$ losetup /dev/loop0 /test/image1
$ losetup /dev/loop1 /test/image2
$ losetup /dev/loop2 /test/image3
$ pvcreate /dev/loop[0,1,2]
  Physical volume "/dev/loop[0,1,2]" successfully created
$ vgcreate -s 1K vg_mirror_test /dev/loop0 /dev/loop1 /dev/loop2
  Volume group "vg_mirror_test" successfully created
$ lvcreate -L 64M -m 1 -n lv_mirror1 vg_mirror_test /dev/loop0 /dev/loop1 /dev/loop2:0-0
  /dev/cdrom: open failed: Read-only file system
 
No more output shown.

  
Actual results:
dmesg and /var/log/messages shows this:
 
===
Nov  4 17:43:17 nagtest-web1 lvm[16895]: Log device, 253:2, has failed.  
Nov  4 17:43:17 nagtest-web1 lvm[16895]: Device failure in vg_mirror_test-lv_mirror1
Nov  4 17:43:17 nagtest-web1 lvm[16895]: WARNING: dev_open(/etc/lvm/lvm.conf) called while suspended
Nov  4 17:43:16 nagtest-web1 kernel: attempt to access beyond end of device
Nov  4 17:43:22 nagtest-web1 kernel: dm-2: rw=16, want=3, limit=2
Nov  4 17:43:22 nagtest-web1 kernel: device-mapper: mirror log: Failed to read header on mirror log device, 253:2
Nov  4 17:43:22 nagtest-web1 kernel: attempt to access beyond end of device
Nov  4 17:43:22 nagtest-web1 kernel: dm-2: rw=17, want=3, limit=2
Nov  4 17:43:22 nagtest-web1 kernel: device-mapper: mirror log: Failed to write header on mirror log device, 253:2
Nov  4 17:43:22 nagtest-web1 kernel: device-mapper: raid1: log resume failed
Nov  4 17:43:22 nagtest-web1 kernel: attempt to access beyond end of device
Nov  4 17:43:22 nagtest-web1 kernel: dm-2: rw=17, want=3, limit=2
Nov  4 17:43:22 nagtest-web1 kernel: attempt to access beyond end of device
Nov  4 17:43:22 nagtest-web1 kernel: dm-2: rw=17, want=3, limit=2
Nov  4 17:43:22 nagtest-web1 kernel: attempt to access beyond end of device
===
'top' lists the kmirrord process with high cpu utilization:
PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
5541 root      20  -5     0    0    0 R 95.9  0.0  12:30.75 kmirrord
===
 
The errors continue forever ...
It seems that a 1K mirror log (because the size of the mirror log is equal to the size of the VG phsical extend) isn't big enough to hold the log information!


Expected results:
$ lvcreate -L 64M -m 1 -n lv_mirror1 vg_mirror_test /dev/loop0 /dev/loop1 /dev/loop2:0-0
  /dev/cdrom: open failed: Read-only file system
  Logical volume "lv_mirror1" created 


Additional info:
This also works on Fedora 10 (Rawhide)!

$ lvm version
  LVM version:     2.02.39-RHEL5 (2008-06-27)
  Library version: 1.02.27 (2008-06-25)
  Driver version:  4.14.0