fs: Factor inode hash operations into functions

Before replacing the inode hash locking with a more scalable
mechanism, factor the removal of the inode from the hashes rather
than open coding it in several places.

Based on a patch originally from Nick Piggin.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/inode.c

@@ -336,6 +336,58 @@ static void inode_lru_list_del(struct inode *inode)
 	}
 }
 
+static unsigned long hash(struct super_block *sb, unsigned long hashval)
+{
+	unsigned long tmp;
+
+	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
+			L1_CACHE_BYTES;
+	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
+	return tmp & I_HASHMASK;
+}
+
+/**
+ *	__insert_inode_hash - hash an inode
+ *	@inode: unhashed inode
+ *	@hashval: unsigned long value used to locate this object in the
+ *		inode_hashtable.
+ *
+ *	Add an inode to the inode hash for this superblock.
+ */
+void __insert_inode_hash(struct inode *inode, unsigned long hashval)
+{
+	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
+	spin_lock(&inode_lock);
+	hlist_add_head(&inode->i_hash, head);
+	spin_unlock(&inode_lock);
+}
+EXPORT_SYMBOL(__insert_inode_hash);
+
+/**
+ *	__remove_inode_hash - remove an inode from the hash
+ *	@inode: inode to unhash
+ *
+ *	Remove an inode from the superblock.
+ */
+static void __remove_inode_hash(struct inode *inode)
+{
+	hlist_del_init(&inode->i_hash);
+}
+
+/**
+ *	remove_inode_hash - remove an inode from the hash
+ *	@inode: inode to unhash
+ *
+ *	Remove an inode from the superblock.
+ */
+void remove_inode_hash(struct inode *inode)
+{
+	spin_lock(&inode_lock);
+	hlist_del_init(&inode->i_hash);
+	spin_unlock(&inode_lock);
+}
+EXPORT_SYMBOL(remove_inode_hash);
+
 void end_writeback(struct inode *inode)
 {
 	might_sleep();
@@ -383,7 +435,7 @@ static void dispose_list(struct list_head *head)
 		evict(inode);
 
 		spin_lock(&inode_lock);
-		hlist_del_init(&inode->i_hash);
+		__remove_inode_hash(inode);
 		list_del_init(&inode->i_sb_list);
 		spin_unlock(&inode_lock);
 
@@ -634,16 +686,6 @@ repeat:
 	return node ? inode : NULL;
 }
 
-static unsigned long hash(struct super_block *sb, unsigned long hashval)
-{
-	unsigned long tmp;
-
-	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
-			L1_CACHE_BYTES;
-	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
-	return tmp & I_HASHMASK;
-}
-
 static inline void
 __inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
 			struct inode *inode)
@@ -1194,36 +1236,6 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
 }
 EXPORT_SYMBOL(insert_inode_locked4);
 
-/**
- *	__insert_inode_hash - hash an inode
- *	@inode: unhashed inode
- *	@hashval: unsigned long value used to locate this object in the
- *		inode_hashtable.
- *
- *	Add an inode to the inode hash for this superblock.
- */
-void __insert_inode_hash(struct inode *inode, unsigned long hashval)
-{
-	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
-	spin_lock(&inode_lock);
-	hlist_add_head(&inode->i_hash, head);
-	spin_unlock(&inode_lock);
-}
-EXPORT_SYMBOL(__insert_inode_hash);
-
-/**
- *	remove_inode_hash - remove an inode from the hash
- *	@inode: inode to unhash
- *
- *	Remove an inode from the superblock.
- */
-void remove_inode_hash(struct inode *inode)
-{
-	spin_lock(&inode_lock);
-	hlist_del_init(&inode->i_hash);
-	spin_unlock(&inode_lock);
-}
-EXPORT_SYMBOL(remove_inode_hash);
 
 int generic_delete_inode(struct inode *inode)
 {
@@ -1279,7 +1291,7 @@ static void iput_final(struct inode *inode)
 		spin_lock(&inode_lock);
 		WARN_ON(inode->i_state & I_NEW);
 		inode->i_state &= ~I_WILL_FREE;
-		hlist_del_init(&inode->i_hash);
+		__remove_inode_hash(inode);
 	}
 	WARN_ON(inode->i_state & I_NEW);
 	inode->i_state |= I_FREEING;
@@ -1294,9 +1306,7 @@ static void iput_final(struct inode *inode)
 	list_del_init(&inode->i_sb_list);
 	spin_unlock(&inode_lock);
 	evict(inode);
-	spin_lock(&inode_lock);
-	hlist_del_init(&inode->i_hash);
-	spin_unlock(&inode_lock);
+	remove_inode_hash(inode);
 	wake_up_inode(inode);
 	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
 	destroy_inode(inode);