fs: change d_hash for rcu-walk

Change d_hash so it may be called from lock-free RCU lookups. See similar
patch for d_compare for details.

For in-tree filesystems, this is just a mechanical change.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 9a76f8d..a15ee20 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -10,7 +10,8 @@
 --------------------------- dentry_operations --------------------------
 prototypes:
 	int (*d_revalidate)(struct dentry *, int);
-	int (*d_hash) (struct dentry *, struct qstr *);
+	int (*d_hash)(const struct dentry *, const struct inode *,
+			struct qstr *);
 	int (*d_compare)(const struct dentry *, const struct inode *,
 			const struct dentry *, const struct inode *,
 			unsigned int, const char *, const struct qstr *);
@@ -22,7 +23,7 @@
 locking rules:
 		dcache_lock	rename_lock	->d_lock	may block
 d_revalidate:	no		no		no		yes
-d_hash		no		no		no		yes
+d_hash		no		no		no		no
 d_compare:	no		yes		no		no 
 d_delete:	yes		no		yes		no
 d_release:	no		no		no		yes