[PATCH] v9fs: simplify fid mapping

v9fs has been plagued by an over-complicated approach trying to map Linux
dentry semantics to Plan 9 fid semantics.  Our previous approach called for
aggressive flushing of the dcache resulting in several problems (including
wierd cwd behavior when running /bin/pwd).

This patch dramatically simplifies our handling of this fid management.  Fids
will not be clunked as promptly, but the new approach is more functionally
correct.  We now clunk un-open fids only when their dentry ref_count reaches 0
(and d_delete is called).

Another simplification is we no longer seek to match fids to the process-id or
uid of the action initiator.  The uid-matching will need to be revisited when
we fix the security model.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/9p/v9fs.c

@@ -397,6 +397,7 @@ v9fs_session_init(struct v9fs_session_info *v9ses,
 	}
 
 	if (v9ses->afid != ~0) {
+		dprintk(DEBUG_ERROR, "afid not equal to ~0\n");
 		if (v9fs_t_clunk(v9ses, v9ses->afid))
 			dprintk(DEBUG_ERROR, "clunk failed\n");
 	}