fs: rename current get acl method

The current way of setting and getting posix acls through the generic
xattr interface is error prone and type unsafe. The vfs needs to
interpret and fixup posix acls before storing or reporting it to
userspace. Various hacks exist to make this work. The code is hard to
understand and difficult to maintain in it's current form. Instead of
making this work by hacking posix acls through xattr handlers we are
building a dedicated posix acl api around the get and set inode
operations. This removes a lot of hackiness and makes the codepaths
easier to maintain. A lot of background can be found in [1].

The current inode operation for getting posix acls takes an inode
argument but various filesystems (e.g., 9p, cifs, overlayfs) need access
to the dentry. In contrast to the ->set_acl() inode operation we cannot
simply extend ->get_acl() to take a dentry argument. The ->get_acl()
inode operation is called from:

acl_permission_check()
-> check_acl()
   -> get_acl()

which is part of generic_permission() which in turn is part of
inode_permission(). Both generic_permission() and inode_permission() are
called in the ->permission() handler of various filesystems (e.g.,
overlayfs). So simply passing a dentry argument to ->get_acl() would
amount to also having to pass a dentry argument to ->permission(). We
should avoid this unnecessary change.

So instead of extending the existing inode operation rename it from
->get_acl() to ->get_inode_acl() and add a ->get_acl() method later that
passes a dentry argument and which filesystems that need access to the
dentry can implement instead of ->get_inode_acl(). Filesystems like cifs
which allow setting and getting posix acls but not using them for
permission checking during lookup can simply not implement
->get_inode_acl().

This is intended to be a non-functional change.

Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
Suggested-by/Inspired-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

3 files changed, 5 insertions, 5 deletions

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 2466edc57424..9306e10753f9 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2487,9 +2487,9 @@ static void ksmbd_acls_fattr(struct smb_fattr *fattr,
 	fattr->cf_dacls = NULL;
 
 	if (IS_ENABLED(CONFIG_FS_POSIX_ACL)) {
-		fattr->cf_acls = get_acl(inode, ACL_TYPE_ACCESS);
+		fattr->cf_acls = get_inode_acl(inode, ACL_TYPE_ACCESS);
 		if (S_ISDIR(inode->i_mode))
-			fattr->cf_dacls = get_acl(inode, ACL_TYPE_DEFAULT);
+			fattr->cf_dacls = get_inode_acl(inode, ACL_TYPE_DEFAULT);
 	}
 }
 
diff --git a/fs/ksmbd/smbacl.c b/fs/ksmbd/smbacl.c
index a1e05fe997fe..ab5c68cc0e13 100644
--- a/fs/ksmbd/smbacl.c
+++ b/fs/ksmbd/smbacl.c
@@ -1289,7 +1289,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 	}
 
 	if (IS_ENABLED(CONFIG_FS_POSIX_ACL)) {
-		posix_acls = get_acl(d_inode(path->dentry), ACL_TYPE_ACCESS);
+		posix_acls = get_inode_acl(d_inode(path->dentry), ACL_TYPE_ACCESS);
 		if (posix_acls && !found) {
 			unsigned int id = -1;
 
diff --git a/fs/ksmbd/vfs.c b/fs/ksmbd/vfs.c
index 7dee8b78762d..93f65f01a4a6 100644
--- a/fs/ksmbd/vfs.c
+++ b/fs/ksmbd/vfs.c
@@ -1375,7 +1375,7 @@ static struct xattr_smb_acl *ksmbd_vfs_make_xattr_posix_acl(struct user_namespac
 	if (!IS_ENABLED(CONFIG_FS_POSIX_ACL))
 		return NULL;
 
-	posix_acls = get_acl(inode, acl_type);
+	posix_acls = get_inode_acl(inode, acl_type);
 	if (!posix_acls)
 		return NULL;
 
@@ -1884,7 +1884,7 @@ int ksmbd_vfs_inherit_posix_acl(struct user_namespace *user_ns,
 	if (!IS_ENABLED(CONFIG_FS_POSIX_ACL))
 		return -EOPNOTSUPP;
 
-	acls = get_acl(parent_inode, ACL_TYPE_DEFAULT);
+	acls = get_inode_acl(parent_inode, ACL_TYPE_DEFAULT);
 	if (!acls)
 		return -ENOENT;
 	pace = acls->a_entries;