Re: [PATCH 03/32] VFS: Introduce the basic header for the new mount API's filesystem context [ver #8]

[Al Viro]

On Fri, May 25, 2018 at 01:05:43AM +0100, David Howells wrote:
> +	bool			drop_sb:1;	/* T if need to drop an SB reference */

IMO that should be simply fc->root != NULL - if you keep a dentry, you'd better
make sure that its superblock has an active reference, so deactivate_super()
is needed anyway.