David Miller a écrit :

From: Eric Dumazet <redacted>
Date: Tue, 31 Oct 2006 19:48:48 +0100

quoted

We currently insert sockets/pipes dentries into the global dentry
hashtable.  This is *useless* because there is currently no way
these entries can be used for a lookup(). (/proc/xxx/fd/xxx uses a
different mechanism)

It turns out that while procfs uses a different "mechanism", those
procfs symlinks do point to the real socket dentry, so when you
readlink() on it you do d_path() on the real socket dentry.

If you unhash these things, I'm pretty sure you'll see an ugly
"(deleted)" at the end of the symlink string for /proc/$pid/fd/$X
files that are sockets or something like that.

No no, my patch takes care of that.

You still see the right link for pipes and sockets on /proc/$pid/fd/XXX

And " (deleted)" is correctly added to deleted files.

Al Viro just suggested a way around this to me:

1) Just mark the dentry HASHED by hand in the dentry flags, but don't
   actually hash it.

2) Create a special dentry->d_deleted method for sockets that returns
   0 and clears by hand the HASHED flag bit in the dentry (see what
   dput() does when this happens).

It's an abuse but it will work.

Why hack when a proper thing can be done ?