lvrename fails to clear blkid cache

[Isaac M. Marcos]

Hello:
I found a problem that I'm not shure to report as a bug, I would like your input to asscertain that it is indeed worth filing a bug.

Short description:
On using lvrename with UUID I get a failure to mount a "logical volume".

As I understand, the sequence to rename a "logical volume" should be:
	umount /dev/VG4/test
	lvrename /dev/VG4/test /dev/VG4/newtest
	mount -a
The mount command fails with a " the special device UUID=(...) doesn't exist."

Conditions:
kernel:			Linux 2.6.25-2-amd64 #1 SMP GNU/Linux
OS:				Debian testing
lvm2 version:		2.02.39-2

Detailed sequence:

fstab contains only one line related to the partition:
zeus:/home#cat /etc/fstab | grep test
UUID=5e5c9ec4-b8d7-4670-a71a-54d1aee6632a       /home/test              ext3    defaults,acl            0               9

Mount works without a problem:
zeus:/home#mount -a

The "logical volume" is correctly mounted:
zeus:/home#mount | grep test
/dev/mapper/VG4-Ltest on /home/test type ext3 (rw,acl)

The "logical volume" is correct:
zeus:/home# lvs | grep test
  Ltest  VG4  -wi-a- 24,56G

lvrename works correctly:
zeus:/home# lvrename VG4 Ltest Ltes
  Renamed "Ltest" to "Ltes" in volume group "VG4"

Mount the affected volume fails to work:
zeus:/home# mount -a
mount: the special device UUID=5e5c9ec4-b8d7-4670-a71a-54d1aee6632a doesn't exist.


Being at this point in a very limited time window I opted to erase the failing volume and recreated it with a new
name, leaving for latter finding what the real problem was.
After recreating the situation with a new volume, I got conviced this was a "real" problem and not a failure on my part.
To find "what" was the real problem, got me into looking for what/who was making the UUID of the device fail.

Detail of some info after the lvrename:
The "logical volume" exists:
zeus:/home# lvs | grep Ltes
  Ltes   VG4  -wi-a- 24,56G

The "logical volume" is ACTIVE:
zeus:/home# lvscan | grep Ltes
  ACTIVE            '/dev/VG4/Ltest' [24,56 GB] inherit

The "logical volume" is correctly allocated:
zeus:/home# lvdisplay
  --- Logical volume ---
  LV Name                /dev/VG4/Ltest
  VG Name                VG4
  LV UUID                zGwUqV-Ckn4-hJuV-KdYG-Ub2Q-ibl6-FBghTP
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                24,56 GB
  Current LE             6288
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:12

The UUID of the corresponding ext3 filesystem is correct:
zeus:/home# dumpe2fs /dev/VG4/Ltes
dumpe2fs 1.41.0 (10-Jul-2008)
Filesystem UUID:          5e5c9ec4-b8d7-4670-a71a-54d1aee6632a


Q:	So, why this "logical volume" fails to mount with "mount -a"?
Finally I discovered that there is a cache system for UUID provided by blkid.tab 
Erasing the failing line on that file corrected the problem. Or making a "blkid -g" could work as well.
A:	blkid.tab is holding a stale line with wrong info.

Erase the line in blkid.tab:
zeus:/home#vi /etc/blkid.tab --> eliminate line with Ltest

Make blkid re-scan the devices:
zeus:/home#blkid | grep Ltes
/dev/mapper/VG4-Ltes: UUID="5e5c9ec4-b8d7-4670-a71a-54d1aee6632a" SEC_TYPE="ext2" TYPE="ext3"

And "mount -a" works correctly.


Conclusion:
lvrename should erase any reference to the name it is making unavailable from blkid.tab
Could we spare others to have the same problems?

Thanks for your attention in advance.

-- 
Isaac M. Marcos