What should dcache routines should be called at the end of mkdir?

[David Howells <dhowells@redhat.com>]

Hi Al,

What d_xxx() functions should I call at the end of a filesystem mkdir() op?

It would seem that I've got two choices:

 (1) just d_instantiate() (as ext2), or

 (2) d_instantiate() and d_rehash() both (as NFS).

If I pick (1), then if I do:

	mkdir /afs/.cambridge.redhat.com/afsdoc/jump/q

I see:

	==> afs_permission({{20000001:1},0},1,)
	==> afs_d_revalidate({v={20000001:6} n=.cambridge.redhat.com fl=20},)
	==> afs_permission({{20000003:1},0},1,)
	==> afs_d_revalidate({v={20000003:2} n=afsdoc fl=20},)
	==> afs_permission({{20000006:1},0},1,)
	==> afs_d_revalidate({v={20000006:5} n=jump fl=0},)
	==> afs_permission({{20000006:5},0},1,)
	==> afs_permission({{20000006:5},0},1,)
	==> afs_lookup({20000006:5},ffff81003344cac8{q},)
	==> afs_permission({{20000006:5},0},3,)
	==> afs_mkdir({20000006:5},{q},755)
	    vnode modified 13 on {20000006:5}
	    not hashed
	==> afs_d_delete(jump)

The "not hashed" indicates that d_unhashed() was true when called after the
d_instantiate().

And then if I do:

	ls /afs/.cambridge.redhat.com/afsdoc/jump/q

I see:

	==> afs_permission({{20000001:1},0},1,)
	==> afs_d_revalidate({v={20000001:6} n=.cambridge.redhat.com fl=20},)
	==> afs_permission({{20000003:1},0},1,)
	==> afs_d_revalidate({v={20000003:2} n=afsdoc fl=20},)
	==> afs_permission({{20000006:1},0},1,)
	==> afs_d_revalidate({v={20000006:5} n=jump fl=c},)
	==> afs_permission({{20000006:5},c},1,)
	==> afs_lookup({20000006:5},ffff81003344c9c0{q},)
	    zap data {20000006:5}
	==> afs_d_delete(q)

In this case, afs_lookup() is called extraneously...  But it does seem to
work.


However, if I pick (2), an do the mkdir, I see:

	==> afs_permission({{20000001:1},0},1,)
	...
	==> afs_lookup({20000006:5},ffff81003344c180{q},)
	==> afs_permission({{20000006:5},0},3,)
	==> afs_mkdir({20000006:5},{q},755)
	    vnode modified 1b on {20000006:5}
	    not hashed

Which is as before, except that afs_d_delete() is *not* called.  Then if do
the "ls" again, I see:

	==> afs_permission({{20000001:1},0},1,)
	==> afs_d_revalidate({v={20000001:6} n=.cambridge.redhat.com fl=20},)
	==> afs_permission({{20000003:1},0},1,)
	==> afs_d_revalidate({v={20000003:2} n=afsdoc fl=20},)
	==> afs_permission({{20000006:1},0},1,)
	==> afs_d_revalidate({v={20000006:5} n=jump fl=c},)
	==> afs_permission({{20000006:5},c},1,)
	==> afs_permission({{20000001:1},0},1,)
	==> afs_d_revalidate({v={20000001:6} n=.cambridge.redhat.com fl=20},)
	==> afs_permission({{20000003:1},0},1,)
	==> afs_d_revalidate({v={20000003:2} n=afsdoc fl=20},)
	==> afs_permission({{20000006:1},0},1,)
	==> afs_d_revalidate({v={20000006:5} n=jump fl=c},)
	==> afs_permission({{20000006:5},c},1,)
	==> afs_permission({{20000006:7},0},4,)

There's no call to afs_d_revalidate() for 'q' which is decidedly fishy...
Furthermore:

 (1) d_release() isn't called for 'q' when I unmount the filesystem.

 (2) if I delete 'q' on the server and do the ls again, then although listing
     jump no longer shows 'q' to be there, the dentry is clearly still there
     as I can list it directly:

	[root@andromeda ~]# mkdir /afs/.cambridge.redhat.com/afsdoc/jump/q
	[root@andromeda ~]# ls /afs/.cambridge.redhat.com/afsdoc/jump/q
	[root@andromeda ~]# ls /afs/.cambridge.redhat.com/afsdoc/jump
	q/
     <delete 'q' on server>
	[root@andromeda ~]# ls /afs/.cambridge.redhat.com/afsdoc/jump
	[root@andromeda ~]# ls /afs/.cambridge.redhat.com/afsdoc/jump/q
	[root@andromeda ~]#

Any suggestions as what I need to do?  I've tried working it out from NFS, but
I must have missed something.

David