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

[Christian Brauner]

On Thu, Sep 29, 2022 at 10:17:27AM +0200, Christoph Hellwig wrote:
> > +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.

Ok, sounds good.

> 
> > +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.

I'll see if a little helper makes more sense than open-coding.

> 
> > +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?

Yeah, we should probably -EOPNOTSUPP for all of:
vfs_{get,set,remove}_acl() in this case. Good point, thanks!