[OpenAFS-devel] afs_linux_dentry_revalidate and d_drop

[chas williams - CONTRACTOR]

On Thu, 13 Mar 2014 17:40:34 -0500
Andrew Deason <adeason@sinenomine.net> wrote:

> I haven't looked too closely at this, but I expect that this previously
> worked because after removing the mountpoint, the dentry revalidate
> would fail and we'd d_drop it. We never explicitly d_drop for an 'fs
> rmm' as far as I can tell, so with 1.6.x right now it sticks around and
> Linux I guess keeps using it....?

I think (it has been a while) that the pioctl() happens, a callback
from the fileserver occurs, and the version number for the afs inode and
dentry no longer match for the containing directory forcing a
revalidate of the directory's contents.

It does feel like there could be a race in there as well.

> One possible way of improving this is to maybe d_drop in
> afs_linux_dentry_revalidate if we know that the entry does in fact no
> longer exist (ENOENT), and d_invalidate for all other errors. But I'm
> not sure if that's necessary or at all correct.

This might be a candidate for sillyrename.  Something is in use but
hasn't lost all references just yet.