filesystems: add missing nlink wrappers

Replace direct i_nlink updates with the respective updater function
(inc_nlink, drop_nlink, clear_nlink, inode_dec_link_count).

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index f1dce84..e8d61b1 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -577,8 +577,7 @@
 
 	fi = udf_add_entry(dir, dentry, &fibh, &cfi, &err);
 	if (!fi) {
-		inode->i_nlink--;
-		mark_inode_dirty(inode);
+		inode_dec_link_count(inode);
 		iput(inode);
 		return err;
 	}
@@ -618,8 +617,7 @@
 	init_special_inode(inode, mode, rdev);
 	fi = udf_add_entry(dir, dentry, &fibh, &cfi, &err);
 	if (!fi) {
-		inode->i_nlink--;
-		mark_inode_dirty(inode);
+		inode_dec_link_count(inode);
 		iput(inode);
 		return err;
 	}
@@ -665,8 +663,7 @@
 	inode->i_fop = &udf_dir_operations;
 	fi = udf_add_entry(inode, NULL, &fibh, &cfi, &err);
 	if (!fi) {
-		inode->i_nlink--;
-		mark_inode_dirty(inode);
+		inode_dec_link_count(inode);
 		iput(inode);
 		goto out;
 	}
@@ -683,7 +680,7 @@
 
 	fi = udf_add_entry(dir, dentry, &fibh, &cfi, &err);
 	if (!fi) {
-		inode->i_nlink = 0;
+		clear_nlink(inode);
 		mark_inode_dirty(inode);
 		iput(inode);
 		goto out;