[newnfs/client] -alldirs: listing files consumes too much memory

[Rick Macklem]

On Thu, 16 Jul 2009, Anonymous wrote:

> Let's create 335 empty files in /blah and try to list them over nfsv3.
>
> # uname -vm
> FreeBSD 8.0-BETA1 #0: Sat Jul  4 03:55:14 UTC 2009     root at almeida.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
>
> # mkdir /blah
> # (while [ $((i+=1)) -le 334 ]; do : >/blah/foo_$i; done)
> # echo / -alldirs >/etc/exports
> # /etc/rc.d/nfsd onestart
> # mount -t newnfs -o nfsv3 0:/blah /mnt
>
Well, this turns out more interesting than I expected. The problem occurs
when there is a large directory "at the mount point only". If you:
# mount -t newnfs -o nfsv3 0:/ /mnt
# cd /mnt/blah
# ls
- it works.

When the large directory is at the mount point, it reads the first
block normally but... it then thinks all subsequent blocks are already
in the buffer cache. ie. They come back from getblk() with B_CACHE
already set??? (It then just loops getting blocks forever, since it
won't see the eof if it doesn't try and read from the server.)

Anyone happen to have a clue why that would happen? Why would blocks
on a mount point vnode behave differently than others.

Well, at least it's easy to reproduce, so I can keep poking around
with it, rick.