On Fri, Sep 30, 2022 at 11:43:07AM +0200, Miklos Szeredi wrote: > On Fri, 30 Sept 2022 at 11:09, Christian Brauner <brauner@xxxxxxxxxx> wrote: > > > > On Fri, Sep 30, 2022 at 10:53:05AM +0200, Miklos Szeredi wrote: > > > On Thu, 29 Sept 2022 at 17:31, Christian Brauner <brauner@xxxxxxxxxx> wrote: > > > > > > > This adds a new ->get_acl() inode operations which takes a dentry > > > > argument which filesystems such as 9p, cifs, and overlayfs can implement > > > > to get posix acls. > > > > > > This is confusing. For example overlayfs ends up with two functions > > > that are similar, but not quite the same: > > > > > > ovl_get_acl -> ovl_get_acl_path -> vfs_get_acl -> __get_acl(mnt_userns, ...) > > > > > > ovl_get_inode_acl -> get_inode_acl -> __get_acl(&init_user_ns, ...) > > > > > > So what's the difference and why do we need both? If one can retrive > > > the acl without dentry, then why do we need the one with the dentry? > > > > The ->get_inode_acl() method is called during generic_permission() and > > inode_permission() both of which are called from various filesystems in > > their ->permission inode operations. There's no dentry available during > > the permission inode operation and there are filesystems like 9p and > > cifs that need a dentry. > > This doesn't answer the question about why we need two for overlayfs > and what's the difference between them. Oh sorry, I misunderstood your questions then. The reason why I didn't consolidate them was simply the different in permission checking. So currently in current mainline overlayfs does acl = get_acl() in it's get acl method and does vfs_getxattr() in ovl_posix_acl_xattr_get(). The difference is that vfs_getxattr() goes through regular lsm hooks checking whereas get_acl() does not. So I thought that using get_acl() was done to not call lsm hooks in there. If that's not the case then I can consolidate both into one implementation.
