new helper: inode_fake_hash()

open-coded in a quite a few places...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/hfs/inode.c

@@ -541,7 +541,7 @@ static struct dentry *hfs_file_lookup(struct inode *dir, struct dentry *dentry,
 	HFS_I(inode)->rsrc_inode = dir;
 	HFS_I(dir)->rsrc_inode = inode;
 	igrab(dir);
-	hlist_add_fake(&inode->i_hash);
+	inode_fake_hash(inode);
 	mark_inode_dirty(inode);
 	dont_mount(dentry);
 out:

fs/jfs/jfs_imap.c

@@ -491,13 +491,7 @@ struct inode *diReadSpecial(struct super_block *sb, ino_t inum, int secondary)
 	/* release the page */
 	release_metapage(mp);
 
-	/*
-	 * __mark_inode_dirty expects inodes to be hashed.  Since we don't
-	 * want special inodes in the fileset inode space, we make them
-	 * appear hashed, but do not put on any lists.  hlist_del()
-	 * will work fine and require no locking.
-	 */
-	hlist_add_fake(&ip->i_hash);
+	inode_fake_hash(ip);
 
 	return (ip);
 }

fs/jfs/super.c

@@ -581,7 +581,7 @@ static int jfs_fill_super(struct super_block *sb, void *data, int silent)
 	inode->i_ino = 0;
 	inode->i_size = i_size_read(sb->s_bdev->bd_inode);
 	inode->i_mapping->a_ops = &jfs_metapage_aops;
-	hlist_add_fake(&inode->i_hash);
+	inode_fake_hash(inode);
 	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
 
 	sbi->direct_inode = inode;

fs/xfs/xfs_iops.c

@@ -1253,7 +1253,7 @@ xfs_setup_inode(
 
 	inode_sb_list_add(inode);
 	/* make the inode look hashed for the writeback code */
-	hlist_add_fake(&inode->i_hash);
+	inode_fake_hash(inode);
 
 	inode->i_uid    = xfs_uid_to_kuid(ip->i_d.di_uid);
 	inode->i_gid    = xfs_gid_to_kgid(ip->i_d.di_gid);

include/linux/fs.h

@@ -684,6 +684,17 @@ static inline int inode_unhashed(struct inode *inode)
 	return hlist_unhashed(&inode->i_hash);
 }
 
+/*
+ * __mark_inode_dirty expects inodes to be hashed.  Since we don't
+ * want special inodes in the fileset inode space, we make them
+ * appear hashed, but do not put on any lists.  hlist_del()
+ * will work fine and require no locking.
+ */
+static inline void inode_fake_hash(struct inode *inode)
+{
+	hlist_add_fake(&inode->i_hash);
+}
+
 /*
  * inode->i_mutex nesting subclasses for the lock validator:
  *