Re: VOP_PUTPAGE ignores mount_nfs -o soft,intr

[David Holland <dholland-tech%netbsd.org@localhost>]

On Fri, Jun 19, 2015 at 05:42:45PM +0000, Christos Zoulas wrote:
 > >This cv_wait() is tiemout-less and uninterruptible. ioflush will 
 > >sleep there forever, holding vnode lock. Any other process doing
 > >I/O on the filesystem will sleep in tstile waiting for the vnode
 > >lock with this path: 
 > >sys_write / dofilewrite / vn_write / vn_lock / VOP_LOCK / rw_enter
 > 
 > Yes, but ioflush is not a user process... An interruptible mount
 > means that a user process can interrupt a syscall doing an NFS
 > operation. No other operating system I know of, takes this to mean
 > that you can unmount the filesystem or make delayed writes abort
 > and fail.

Sure. But it also doesn't mean that there should be cases where I/O to
the filesystem hangs uninterruptibly.

Nothing is supposed to hang in tstile; therefore, this wait is
incorrect...

 > Having said that, yes it is a problem that you need to reboot
 > because an NFS server is gone, and we should make umount -f work
 > properly in that case. I don't think that we should introduce umount
 > -l (like linux) unless there is a compelling reason to do so.

I would say we want umount -l, but it's both not trivial and not a
solution to this problem.

-- 
David A. Holland
dholland%netbsd.org@localhost