[RFC PATCH 01/11] exportfs: add ability to advertise NFSv4 ACL passthru support

[Mike Snitzer <snitzer@kernel.org>]

From: Mike Snitzer <snitzer@hammerspace.com>

Add EXPORT_OP_NFSV4_ACL_PASSTHRU flag that an export should set if
relevant new methods are added to export_operations (e.g. .setacl and
.getacl which will be added in future commits).

NFSD will use exportfs_may_passthru_nfs4acl() to check for this flag
before passing nfs4_acl thru to exported FS (using new methods in
export_operations).

Signed-off-by: Mike Snitzer <snitzer@hammerspace.com>
---
 include/linux/exportfs.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index 9369a607224c..0262c9258b34 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -247,6 +247,7 @@ struct export_operations {
 						*/
 #define EXPORT_OP_FLUSH_ON_CLOSE	(0x20) /* fs flushes file data on close */
 #define EXPORT_OP_NOLOCKS		(0x40) /* no file locking support */
+#define EXPORT_OP_NFSV4_ACL_PASSTHRU	(0x80) /* fs MAY handle NFSv4 ACL passthru */
 	unsigned long	flags;
 };
 
@@ -262,6 +263,18 @@ exportfs_cannot_lock(const struct export_operations *export_ops)
 	return export_ops->flags & EXPORT_OP_NOLOCKS;
 }
 
+/**
+ * exportfs_may_passthru_nfs4acl() - check if export MAY passthru NFSv4 ACLs
+ * @export_ops:	the nfs export operations to check
+ *
+ * Returns true if the export MAY support NFSv4 ACL passthru.
+ */
+static inline bool
+exportfs_may_passthru_nfs4acl(const struct export_operations *export_ops)
+{
+	return export_ops->flags & EXPORT_OP_NFSV4_ACL_PASSTHRU;
+}
+
 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
 				    int *max_len, struct inode *parent,
 				    int flags);
-- 
2.44.0