bin/94635: snapinfo/libufs only works for disk-backed filesystems

[Ceri Davies]

>Number:         94635
>Category:       bin
>Synopsis:       snapinfo/libufs only works for disk-backed filesystems
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Mar 18 11:10:10 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Ceri Davies
>Release:        FreeBSD 6.1-PRERELEASE i386
>Organization:
Submonkey
>Environment:
System: FreeBSD shrike.private.submonkey.net 6.1-PRERELEASE FreeBSD 6.1-PRERELEASE #30: Fri Mar 17 16:58:24 GMT 2006 root at shrike.private.submonkey.net:/usr/obj/usr/src/sys/SHRIKE i386

>Description:

My mounted filesystems are currently:

Filesystem           1K-blocks     Used    Avail Capacity  Mounted on
/dev/ad0s1a             507630   110934   356086    24%    /
devfs                        1        1        0   100%    /dev
/dev/md0                253678      558   232826     0%    /tmp
/dev/ad0s1f            8122126  2467276  5005080    33%    /usr
/dev/mirror/userhome  25385514  9353432 14001242    40%    /usr/home
/dev/ad0s1e            4058062   418004  3437156    11%    /usr/local/pgsql
/dev/ad1s1a            1190120   873600   257016    77%    /usr/ports
/dev/ad1s1f           16582478  4024530 11728826    26%    /var
/dev/ad0s1g            4058062        4  3733414     0%    /spare
/dev/stripe/werehaus  65053706 29061010 32740012    47%    /a
devfs                        1        1        0   100%    /var/named/dev
/dev/md1              25385514  8562932 14791742    37%    /snap/20060318-005900/home
/dev/md2              65053706 25343222 36457800    41%    /snap/20060318-005900/a
/dev/md3                507630    52306   414714    11%    /snap/20060318-005900/slash
/dev/md4                253678      104   233280     0%    /snap/20060318-005900/tmp

The recently added snapinfo(8) returns:

# snapinfo -a
ufs_disk_fillout: No such file or directory
ufs_disk_fillout: Unknown error: 0
ufs_disk_fillout: Unknown error: 0
ufs_disk_fillout: Unknown error: 0
ufs_disk_fillout: Unknown error: 0
/.snap/20060314-005900
/.snap/20060315-005901
/.snap/20060316-005900
/.snap/20060317-005900
/.snap/20060318-005900
/usr/home/.snap/20060314-005900
/usr/home/.snap/20060315-005901
/usr/home/.snap/20060316-005900
/usr/home/.snap/20060317-005900
/usr/home/.snap/20060318-005900
/a/.snap/20060314-005900
/a/.snap/20060315-005901
/a/.snap/20060316-005900
/a/.snap/20060317-005900
/a/.snap/20060318-005900

The first three entries are from /dev/md0 through /dev/md4 in that
order, although I'm not sure why the first error is "No such file or
directory", since /dev/md0 does exist.  Verbose examples for both
failure modes:

# snapinfo -v /tmp
ufs_disk_fillout: No such file or directory
(null) mounted on 
        no snapshots found
# snapinfo -v /snap/20060318-005900/a
ufs_disk_fillout: Unknown error: 0
/snap/20060318-005900/a mounted on 
        no snapshots found


>How-To-Repeat:

Mount an md backed filesystem, and run snapinfo against it.

>Fix:

Fix libufs to return something useable in the non-disk case?

>Release-Note:
>Audit-Trail:
>Unformatted: