Red Hat Bugzilla – Bug 204992
snapshot attempt will fail if requested minor is already in use
Last modified: 2013-02-28 23:04:20 EST
Description of problem: [root@taft-04 ~]# lvcreate -n snap10 -My --major 200 --minor 75 -L 50M -s /dev/snapper/origin Rounding up size to full physical extent 52.00 MB Logical volume "snap10" created [root@taft-04 ~]# dmsetup info -c Name Maj Min Stat Open Targ Event UUID snapper-snap10 253 4 L--w 0 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBFfzUpyTp1rA5Ibi7PSrzod0XiLecxvR5 snapper-origin-real 253 2 L--w 2 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBHouLln48K5ddi5v9fOialBRMD1Lkb4VG-real VolGroup00-LogVol01 253 1 L--w 1 1 0 LVM-zUByyTfjW0kZbVav84sw7MJSW2JYnqw5UsN964on4p3rGGX2nMO3T4sYHE3TnkhP VolGroup00-LogVol00 253 0 L--w 1 1 0 LVM-zUByyTfjW0kZbVav84sw7MJSW2JYnqw5ic586KqB9N623SZmXmWa54kFJ3nZM693 snapper-origin 253 3 L--w 0 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBHouLln48K5ddi5v9fOialBRMD1Lkb4VG snapper-snap10-cow 253 75 L--w 1 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBFfzUpyTp1rA5Ibi7PSrzod0XiLecxvR5-cow [root@taft-04 ~]# lvcreate -n snap11 -My --major 200 --minor 75 -L 50M -s /dev/snapper/origin Rounding up size to full physical extent 52.00 MB device-mapper: create ioctl failed: No such device or address device-mapper: reload ioctl failed: No such device or address Failed to suspend origin origin # Seems to work just fine if you're creating a linear [root@taft-04 ~]# lvcreate -n linear -My --major 200 --minor 75 -L 50M snapper Rounding up size to full physical extent 52.00 MB Logical volume "linear" created [root@taft-04 ~]# dmsetup info -c Name Maj Min Stat Open Targ Event UUID snapper-snap11 253 5 ---w 0 0 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBgCBEnxZsGm5t9PFXW7lAQJfRdRWsZqtP snapper-snap10 253 4 L--w 0 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBFfzUpyTp1rA5Ibi7PSrzod0XiLecxvR5 snapper-linear 253 6 L--w 0 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBtd8i3ZAtjSVtHcSVYD89itti61ChA6vK snapper-origin-real 253 2 L--w 2 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBHouLln48K5ddi5v9fOialBRMD1Lkb4VG-real VolGroup00-LogVol01 253 1 L--w 1 1 0 LVM-zUByyTfjW0kZbVav84sw7MJSW2JYnqw5UsN964on4p3rGGX2nMO3T4sYHE3TnkhP VolGroup00-LogVol00 253 0 L--w 1 1 0 LVM-zUByyTfjW0kZbVav84sw7MJSW2JYnqw5ic586KqB9N623SZmXmWa54kFJ3nZM693 snapper-origin 253 3 L--w 0 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBHouLln48K5ddi5v9fOialBRMD1Lkb4VG snapper-snap10-cow 253 75 L--w 1 1 0 LVM-Spo3CrJmpzevPFq2L7Pp3ns8R00FemmBFfzUpyTp1rA5Ibi7PSrzod0XiLecxvR5-cow # Try again with an strace [root@taft-04 ~]# strace -e trace=mknod lvcreate -n snap12 -My --major 200 --minor 75 -L 50M -s /dev/snapper/origin Rounding up size to full physical extent 52.00 MB mknod("/dev/mapper/snapper-snap12", S_IFBLK|0660, makedev(253, 7)) = 0 device-mapper: create ioctl failed: No such device or address device-mapper: reload ioctl failed: No such device or address Failed to suspend origin origin mknod("/dev/mapper/snapper-snap12", S_IFBLK|0660, makedev(253, 7)) = 0 Process 4895 detached # mknod doesn't seem to care if they're already in use [root@taft-03 lvm]# mknod /tmp/FOO b 255 100 [root@taft-03 lvm]# ls -lrt /tmp total 0 brw-r--r-- 1 root root 255, 100 Sep 1 10:15 FOO [root@taft-03 lvm]# mknod /tmp/GLARCH b 255 100 [root@taft-03 lvm]# ls -lrt /tmp total 0 brw-r--r-- 1 root root 255, 100 Sep 1 10:15 FOO brw-r--r-- 1 root root 255, 100 Sep 1 10:15 GLARCH Version-Release number of selected component (if applicable): [root@taft-04 ~]# uname -ar Linux taft-04 2.6.9-42.0.1.ELlargesmp #1 SMP Fri Aug 4 13:04:33 EDT 2006 x86_64 x86_64 x86_64 GNU/Linux [root@taft-04 ~]# rpm -q lvm2 lvm2-2.02.06-6.0.RHEL4 [root@taft-04 ~]# rpm -q device-mapper device-mapper-1.02.07-4.0.RHEL4 How reproducible: everytime
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release.
This request was previously evaluated by Red Hat Product Management for inclusion in the current Red Hat Enterprise Linux release, but Red Hat was unable to resolve it in time. This request will be reviewed for a future Red Hat Enterprise Linux release.
Only just noticed this one - fascinating. This problem might date back to the rewrite of the activation code! Should be straightforward to fix.
Note that the problem is *not* just what it says - the first command in the example is going wrong, assigning the minor number to the cow instead of the final top-level device - because of the way we store the metadata the activation code has to move the device number across internally. This one: snapper-snap10 253 4 L--w 0 1 0 should be 253:75. For the second command, the code should probably check for conflicts when the device node is added to the tree.
Fixed upstream in lvm2 2.02.44.
In lvm2-2.02.42-2.el4.
And fix (together with fix for bug 480838) in lvm2-2.02.42-3.el4.
Fix verified in lvm2-2.02.42-5.el4: [root@hayes-01 ~]# lvcreate -n snap11 -My --major 200 --minor 75 -L 50M -s /dev/grant/origin Rounding up size to full physical extent 52.00 MB The requested major:minor pair (200:75) is already used Aborting. Failed to activate snapshot exception store.
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2009-0967.html