filesystems: add set_nlink()

Replace remaining direct i_nlink updates with a new set_nlink()
updater function.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 180fa24..8179f1a 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -342,7 +342,7 @@
 	inode->i_ino = get_next_ino();
 
 	if (S_ISDIR(mode)) {
-		inode->i_nlink = 2;
+		set_nlink(inode, 2);
 		inode->i_op = &autofs4_dir_inode_operations;
 		inode->i_fop = &autofs4_dir_operations;
 	} else if (S_ISLNK(mode)) {