Another force unmount failure

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

Hello

I discovered another scenario where force unmount could not work: an
unresponsive PUFFS filesystem. The filesystem got out of order during an
operation where the filesystem root vnode is locked. As a result, trying
to unmount goes this way

sys_unmount -> namei -> namei_tryemulroot -> lookup_once -> VFS_ROOT ->
puffs_vfsop_root -> vn_lock -> VOP_LOCK  and we loose.

I can kill the userland process, but the mount remains, an any attempt
to touch it sinks in tstile.

Any idea how can that be fixed?

-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost