[PATCH v3 14/29] acl: add vfs_set_acl()

[Christoph Hellwig]

> +EXPORT_SYMBOL(vfs_set_acl);

I think all this stackable file system infrastucture should be
EXPORT_SYMBOL_GPL, like a lot of the other internal stuff.

> +int xattr_permission(struct user_namespace *mnt_userns, struct inode *inode,
> +		     const char *name, int mask)

Hmm.  The only think ACLs actually need from xattr_permission are
the immutable / append check and the HAS_UNMAPPED_ID one.  I'd rather
open code that, or if you cane come up with a sane name do a smaller
helper rather than doing all the strcmp on the prefixes for now
good reason.

> +static inline int vfs_set_acl(struct user_namespace *mnt_userns,
> +			      struct dentry *dentry, const char *name,
> +			      struct posix_acl *acl)
> +{
> +	return 0;

Should this really return 0 if ACLs are not supported?