misc/151111: vnodes leakage during zfs unmount

[Oleg A. Mamontov]

>Number:         151111
>Category:       misc
>Synopsis:       vnodes leakage during zfs unmount
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Sep 30 12:00:15 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     Oleg A. Mamontov
>Release:        8-STABLE
>Organization:
Rambler Internet Holding
>Environment:
FreeBSD store06.video.rambler.ru 8.0-20100505-SNAP FreeBSD 8.0-20100505-SNAP #0: Wed May  5 07:45:52 UTC 2010     root at nat-sl.rambler.ru:/usr/obj/usr/src/sys/DEVEL  amd64
>Description:
During `zfs mount tank`, `zfs unmount tank` vfs.numvnodes is growing up to kern.maxvnodes.
>How-To-Repeat:
mdconfig -a -s128m -u0
zpool create tank md0
zfs umount tank
for i in `jot 1000`; do zfs mount tank; printf '%4d   ' $i; sysctl vfs.numvnodes; zfs umount tank; done
########################
 1   vfs.numvnodes: 708
 2   vfs.numvnodes: 709
 3   vfs.numvnodes: 710
 4   vfs.numvnodes: 711
 5   vfs.numvnodes: 712

..

995   vfs.numvnodes: 1702
996   vfs.numvnodes: 1703
997   vfs.numvnodes: 1704
998   vfs.numvnodes: 1705
999   vfs.numvnodes: 1706
1000   vfs.numvnodes: 1707

>Fix:


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