bin/68165: df fails to check fs type with -t and inaccessible mount point

[Valentin Nechayev]

>Number:         68165
>Category:       bin
>Synopsis:       df fails to check fs type with -t and inaccessible mount point
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Jun 21 12:00:43 GMT 2004
>Closed-Date:
>Last-Modified:
>Originator:     Valentin Nechayev
>Release:        FreeBSD 4.10-RELEASE i386
>Organization:
Lucky Net Ltd.
>Environment:
System: FreeBSD 4.10-RELEASE

>Description:

Full df output for this host says:

Filesystem  1K-blocks    Used    Avail Capacity  Mounted on
/dev/da0s1a    496111  261683   194740    57%    /
/dev/da0s2e   1977238 1006815   812244    55%    /var
/dev/da0s3e  14515912 5078856  8275784    38%    /var/Backups/important
/dev/da1s1e   4320972 1500900  2474395    38%    /var/Backups/backups
procfs              4       4        0   100%    /proc
/dev/da2s4e  32676496 7719364 22343016    26%    /var/Backups/d2

Monitoring hook runs as nobody; `nobody' has no access inside /var/Backups.
When run `df', all is OK. When run `df -t ufs' as nobody, it says:

Filesystem  1K-blocks    Used   Avail Capacity  Mounted on
/dev/da0s1a    496111  261683  194740    57%    /
/dev/da0s2e   1977238 1006818  812241    55%    /var
/dev/da0s3e  14515912 5078856 8275784    38%    /var/Backups/important
/dev/da1s1e   4320972 1500900 2474395    38%    /var/Backups/backups
procfs              4       4       0   100%    /proc

so it loses /var/Backups/d2 (which is ufs) and prints /proc (which is not ufs).

With access inside /var/Backups, it prints correct:

Filesystem  1K-blocks    Used    Avail Capacity  Mounted on
/dev/da0s1a    496111  261683   194740    57%    /
/dev/da0s2e   1977238 1006815   812244    55%    /var
/dev/da0s3e  14515912 5078856  8275784    38%    /var/Backups/important
/dev/da1s1e   4320972 1500900  2474395    38%    /var/Backups/backups
/dev/da2s4e  32676496 7719364 22343016    26%    /var/Backups/d2

Also, it works OK when /proc is mounted _after_ /var/Backups/d2,
regardless of right to access inside /var/Backups;
but remounting /proc before /var/Backups/d2 triggers the bug again.

>How-To-Repeat:

See above.

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