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/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index b52c672..ae4d9cd 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1641,7 +1641,7 @@
 	inode->i_gid = btrfs_stack_inode_gid(inode_item);
 	btrfs_i_size_write(inode, btrfs_stack_inode_size(inode_item));
 	inode->i_mode = btrfs_stack_inode_mode(inode_item);
-	inode->i_nlink = btrfs_stack_inode_nlink(inode_item);
+	set_nlink(inode, btrfs_stack_inode_nlink(inode_item));
 	inode_set_bytes(inode, btrfs_stack_inode_nbytes(inode_item));
 	BTRFS_I(inode)->generation = btrfs_stack_inode_generation(inode_item);
 	BTRFS_I(inode)->sequence = btrfs_stack_inode_sequence(inode_item);