K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2008-12-18T12:01:19.343459Z
K 7
svn:log
V 505
The quotactl, statfs and fstatfs syscall implementations may dereference
NULL pointer to struct mount if the looked up vnode is reclaimed. Also,
these syscalls only mnt_ref() the mp, still allowing it to be unmounted;
only struct mount memory is kept from being reused.

Lock the vnode when doing name lookup, then reference its mount point,
unlock the vnode and vfs_busy the mountpoint. This sequence shall take
care of both races.

Reported and tested by:	pho
Discussed with:	attilio
MFC after:	1 month

END