Bug 144874

Description of problem:

A volume group which I have converted from lvm1 to lvm2 causes 
problems when attempting to snapshot any logical volume for the 9th 
time.  Note that I can take many snapshots, but it appears shapshot 
number 9 of any LV causes the problem.

Either there is a coded limit of 8 snapshots, and the commands need 
to prevent attempt number 9, or there is a bug trying to take it.

The problem does not appear to be in any way hardware related.
Snapshot # 9 (/dev/rootvg/test9) does not appear.  I can still 
perform vg/lv operations, and can even perform an lvremove of the 
attempted snapshot # 9, but need to reboot to be able to 
access /dev/rootvg/tmp again.

Version-Release number of selected component (if applicable):


How reproducible:

Every time



Steps to Reproduce:
1. Installed basic RH EL3 and upgraded to EL4 beta 2.  All lvm 
filesystems except /boot. (I believe it will happen from a fresh EL4 
install but we had issues with our install disk on the EM64T, so we 
installed EL3 and upgraded).
2. vgconvert -M 2 rootvg (I believe an install straight onto LVM2 
filesystems will also perform the same).
3. Snapshot one of the LVs 8 times...
4. Try to take snapshot # 9 of the same LV:
[root@el4beta test2]# lvcreate -s -L 1M -n test7 /dev/rootvg/tmp
  
Actual results:

Error trying to create snapshot 9:
  Rounding up size to full physical extent 16.00 MB
  device-mapper ioctl cmd 9 failed: Cannot allocate memory
  Couldn't load device 'rootvg-test4'.
  Problem reactivating origin tmp

Note that I was trying to create /dev/rootvg/test7 
(aka /dev/mapper/rootvg-test7) and it says it couldn't load device 
rootvg-test4 - that's not what I asked for!

At this point /tmp is locked and any attempts to access it or a 
mounted snapshot(ls, app uses a temp file, or whatever) are met by a 
system wait.  Other commands/functions as they should.


Expected results:

If this is a limitation (max 8 snapshots of any particular LV), the 
command should have refused politely.  Otherwise the device mapper 
should have created the rootvg-test7 snapshot.


Additional info:

 here is the order they were created in:
[root@el4beta ~]# lvcreate -s -L 1M -n test /dev/rootvg/tmp
  Rounding up size to full physical extent 16.00 MB
  Logical volume "test" created                               (# 1)
[root@el4beta ~]# lvcreate -s -L 1M -n test9 /dev/rootvg/tmp  
Rounding up size to full physical extent 16.00 MB
  Logical volume "test9" created                             (# 2)
[root@el4beta ~]# lvcreate -s -L 1M -n test1 /dev/rootvg/tmp  
Rounding up size to full physical extent 16.00 MB
  Logical volume "test1" created                             (# 3)

... snapshots 4-7 (test2-5) follow along the same lines, finally...

[root@el4beta test2]# lvcreate -s -L 1M -n test6 /dev/rootvg/tmp  
Rounding up size to full physical extent 16.00 MB
  Logical volume "test6" created                         **(# 8)