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/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index 0d22afd..2f72da5 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -541,7 +541,7 @@
 
 	ino->i_ino = st.ino;
 	ino->i_mode = st.mode;
-	ino->i_nlink = st.nlink;
+	set_nlink(ino, st.nlink);
 	ino->i_uid = st.uid;
 	ino->i_gid = st.gid;
 	ino->i_atime = st.atime;