[PATCH] nfsd4: fix delegation filp sharing

The st_vfs_file pointer is set when the open that originally got the delegation
is closed, and then in release_deleg we attempt to distinguish between the case
when the original open has been closed and when it hasn't.  The resulting logic
is complicated and buggy.

It's much simpler just to keep a reference count on the struct file.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/nfsd/nfs4state.c

@@ -145,7 +145,8 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_stateid *stp, struct svc_f
 	dp->dl_client = clp;
 	dp->dl_file = fp;
 	dp->dl_flock = NULL;
-	dp->dl_vfs_file = NULL;
+	get_file(stp->st_vfs_file);
+	dp->dl_vfs_file = stp->st_vfs_file;
 	dp->dl_type = type;
 	dp->dl_recall.cbr_dp = NULL;
 	dp->dl_recall.cbr_ident = cb->cb_ident;
@@ -183,16 +184,6 @@ nfs4_put_delegation(struct nfs4_delegation *dp)
  * the i_flock list, eventually calling nfsd's lock_manager
  * fl_release_callback.
  *
- * call either:
- *   nfsd_close : if last close, locks_remove_flock calls lease_modify.
- *                otherwise, recalled state set to NFS4_RECALL_COMPLETE
- *                so that it will be reaped by the laundromat service.
- * or
- *   remove_lease (calls time_out_lease which calls lease_modify).
- *   and nfs4_free_delegation.
- *
- * Called with nfs_lock_state() held.
- * Called with the recall_lock held.
  */
 
 static void
@@ -203,6 +194,9 @@ nfs4_close_delegation(struct nfs4_delegation *dp)
 	dprintk("NFSD: close_delegation dp %p\n",dp);
 	dp->dl_vfs_file = NULL;
 	atomic_set(&dp->dl_state, NFS4_RECALL_COMPLETE);
+	/* The following nfsd_close may not actually close the file,
+	 * but we want to remove the lease in any case. */
+	remove_lease(dp->dl_flock);
 	nfsd_close(filp);
 	vfsclose++;
 }
@@ -211,18 +205,11 @@ nfs4_close_delegation(struct nfs4_delegation *dp)
 static void
 release_delegation(struct nfs4_delegation *dp)
 {
-	/* delayed nfsd_close */
-	if (dp->dl_vfs_file)
-		nfs4_close_delegation(dp);
-	else {
-		dprintk("NFSD: release_delegation remove lease dl_flock %p\n",
-			dp->dl_flock);
-		remove_lease(dp->dl_flock);
-		list_del_init(&dp->dl_del_perfile);
-		list_del_init(&dp->dl_del_perclnt);
-		list_del_init(&dp->dl_recall_lru);
-		nfs4_put_delegation(dp);
-	}
+	list_del_init(&dp->dl_del_perfile);
+	list_del_init(&dp->dl_del_perclnt);
+	list_del_init(&dp->dl_recall_lru);
+	nfs4_close_delegation(dp);
+	nfs4_put_delegation(dp);
 }
 
 /* 
@@ -1153,38 +1140,22 @@ init_stateid(struct nfs4_stateid *stp, struct nfs4_file *fp, struct nfs4_stateow
 	__set_bit(open->op_share_deny, &stp->st_deny_bmap);
 }
 
-/*
-* Because nfsd_close() can call locks_remove_flock() which removes leases,
-* delay nfsd_close() for delegations from the nfsd_open() clientid
-* until the delegation is reaped.
-*/
 static void
 release_stateid(struct nfs4_stateid *stp, int flags)
 {
-	struct nfs4_delegation *dp;
-	struct nfs4_file *fp = stp->st_file;
+	struct file *filp = stp->st_vfs_file;
 
 	list_del(&stp->st_hash);
 	list_del_perfile++;
 	list_del(&stp->st_perfile);
 	list_del(&stp->st_perfilestate);
 	if (flags & OPEN_STATE) {
-		list_for_each_entry(dp, &fp->fi_del_perfile, dl_del_perfile) {
-			if(cmp_clid(&dp->dl_client->cl_clientid,
-			    &stp->st_stateowner->so_client->cl_clientid)) {
-				dp->dl_vfs_file = stp->st_vfs_file;
-				release_stateid_lockowners(stp);
-				return;
-			}
-		}
 		release_stateid_lockowners(stp);
-		nfsd_close(stp->st_vfs_file);
+		stp->st_vfs_file = NULL;
+		nfsd_close(filp);
 		vfsclose++;
-	} else if (flags & LOCK_STATE) {
-		struct file *filp = stp->st_vfs_file;
-
+	} else if (flags & LOCK_STATE)
 		locks_remove_posix(filp, (fl_owner_t) stp->st_stateowner);
-	}
 	kfree(stp);
 	stp = NULL;
 }