Re: [PATCH v18 11/22] vfs: Cache base_acl objects in inodes

From: Christoph Hellwig
Date: Fri Mar 11 2016 - 09:08:02 EST

On Mon, Feb 29, 2016 at 09:17:16AM +0100, Andreas Gruenbacher wrote:
> POSIX ACLs and richacls are both objects allocated by kmalloc() with a
> reference count which are freed by kfree_rcu(). An inode can either
> cache an access and a default POSIX ACL, or a richacl (richacls do not
> have default acls). To allow an inode to cache either of the two kinds
> of acls, introduce a new base_acl type and convert i_acl and
> i_default_acl to that type. In most cases, the vfs then doesn't care which
> kind of acl an inode caches (if any).

This base_acl object is pointless. I've asked in the past to have
a proper container for the ACLs in common code, but a union
of a refcount and a rcu head doesn't really fit that category.

But this points out that the f2fs folks really need a couple of
slaps on their hands. Not if generic funtionality doesn't
fit your needs you are not going to blindly copy and paste it,
please talk to find a solution instead of duplicating it.

Folks, please come up with a suggestion to get rid of f2fs_acl_clone,
f2fs_acl_create_masq and f2fs_acl_create ASAP.