vdev_id.conf slot mapping fails on Debian 7

[ghost]

I originally opened this at https://github.com/zfsonlinux/zfs/issues/2965, but was told it belonged here, so I guess we'll see.

After a ZFS upgrade on a Debian 7 server, my JBOD slot mappings defined in /etc/zfs/vdev_id.conf were broken. When I ran the vdev_id script manually on a device, I got the following:

# /lib/udev/vdev_id -d sde              
awk: line 1: regular expression compile failed (missing operand)
^(A|)$                                                          
ID_VDEV=A9                                                      
ID_VDEV_PATH=disk/by-vdev/A9                                    

The device should actually be mapped to A10 (linux slot 9 mapped to A10), but the awk error prevents the mapping and so the bay_identifier value is used instead. I have an older ZFS version installed on CentOS, and I copied it to this same Debian server, and that scripted worked fine. It appears the change for issue #2056 introduced this problem (specifically this diff: https://github.com/nedbass/zfs/commit/533d96afc85cb102f37eedded5025f5c23c4247a#diff-081bd452e1418e3d0dfab42b86a44142L115). I did a bit more investigation and noticed that the versions of awk are different between Debian and CentOS, the former being "mawk" while the latter is "gawk". Apparently the new syntax is not portable between them. After I installed gawk on the Debian server, the error is gone and my mappings are correct again:

# /lib/udev/vdev_id -d sde                                                                                                                                    
ID_VDEV=A10
ID_VDEV_PATH=disk/by-vdev/A10

I would have suggested adding a gawk dependency to the Debian package, but not sure that will fly. I have found some similar issues that avoided doing so: https://github.com/zfsonlinux/zfs/issues/76 (gawk dependency was removed) and https://github.com/zfsonlinux/zfs/issues/259 (awk usage was replaced)

[FransUrbo]

@dajhorn Do you see any such problem on Ubuntu? Do you depend on gawk (I don't)?

@pinek Thanx for moving it, but I might actually be wrong about having it here, but on the other hand it's an easier fix to put the dependency in the package instead of making sure that /lib/udev/vdev_id works correctly in ZoL... ?

However, I'm not having any trouble using mawk on my Debian GNU/Linux Wheezy machine

# dpkg -l \*awk\*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                              Version               Architecture          Description
+++-=================================-=====================-=====================-========================================================================
un  awk                               <none>                                      (no description available)
un  gawk                              <none>                                      (no description available)
ii  mawk                              1.3.3-17              amd64                 a pattern scanning and text processing language
# which awk
/usr/bin/awk
# ll /usr/bin/awk
lrwxrwxrwx 1 root root 21 Feb  4  2014 /usr/bin/awk -> /etc/alternatives/awk*
# ll /etc/alternatives/awk
lrwxrwxrwx 1 root root 13 Feb  4  2014 /etc/alternatives/awk -> /usr/bin/mawk*
# cat /etc/zfs/vdev_id.conf
alias disk_1a   scsi-SATA_VBOX_HARDDISK_VB1f45d95c-477fd9c6
alias disk_1b   scsi-SATA_VBOX_HARDDISK_VBa23b735b-e12dbf0c
alias disk_2a   scsi-SATA_VBOX_HARDDISK_VB00c23763-14860ab9
alias disk_2b   scsi-SATA_VBOX_HARDDISK_VBd15b7714-c746e03e
alias disk_3a   scsi-SATA_VBOX_HARDDISK_VBe7e12ad6-7394c614
alias disk_3b   scsi-SATA_VBOX_HARDDISK_VB69234b2a-d52afc22
alias disk_4a   scsi-SATA_VBOX_HARDDISK_VBee9d66a1-edf52bff
# zpool status
  pool: rpool
 state: ONLINE
  scan: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        rpool       ONLINE       0     0     0
          disk_1a   ONLINE       0     0     0
          disk_1b   ONLINE       0     0     0

errors: No known data errors

[dajhorn]

@dajhorn Do you see any such problem on Ubuntu?

That expression is good with gawk-4.1.1 and bad with mawk-1.3.3.

Do you depend on gawk (I don't)?

No, which means that this is probably a bug. It could be related to zfsonlinux/pkg-zfs#130 reported earlier by @gbkersey.

[nedbass]

The offending regular expression could be fixed to work with either mawk or gawk. This seems to work:

--- /lib/udev/vdev_id   2014-09-12 11:05:28.000000000 -0700
+++ vdev_id     2014-12-17 10:41:24.187649414 -0800
@@ -116,7 +116,7 @@
        local MAPPED_SLOT=

        MAPPED_SLOT=`awk "\\$1 == \"slot\" && \\$2 == ${LINUX_SLOT} && \
-                       \\$4 ~ /^(${CHANNEL}|)$/ { print \\$3; exit }" $CONFIG`
+               \\$4 ~ /^(${CHANNEL}|\'\')$/ { print \\$3; exit }" $CONFIG`
        if [ -z "$MAPPED_SLOT" ] ; then
                MAPPED_SLOT=$LINUX_SLOT
        fi

[FransUrbo]

That expression is good with gawk-4.1.1 and bad with mawk-1.3.3.

Worked for me on mawk-1.3.3...

[dajhorn]

@nedbass, I get this on Utopic with the busybox that runs most of the pre-init:

$ echo '""' | busybox awk '$1 ~ /^(A|\"\")$/  {print "TRUE";}'
TRUE
$ echo '' | busybox awk '$1 ~ /^(A|\"\")$/  {print "TRUE";}'
TRUE
$ echo '""' | busybox awk '$1 ~ /^(A|"")$/  {print "TRUE";}'
TRUE
$ echo '' | busybox awk '$1 ~ /^(A|"")$/  {print "TRUE";}'

Is this expected behavior? -- It seems like the literal quote handling is ambiguous.

[nedbass]

@dajhorn my original diff with double-quotes was broken, as you discovered. I updated it to use single quotes which seem to work as intended.

[nedbass]

The quoting is problematic in any form I've tried. Instead I moved the ^$ anchors inside the alternation.

[behlendorf]

Thanks guys, the updated patch appears to work properly with both mawk and gawk. I've merged it as:

2d9d57b vdev_id: use mawk-compatible regular expression