orangefs: add features op

This is a new userspace operation, which will be done if the client-core
version is greater than or equal to 2.9.6. This will provide a way to
implement optional features and to determine which features are
supported by the client-core. If the client-core version is older than
2.9.6, no optional features are supported and the op will not be done.

The intent is to allow protocol extensions without relying on the
client-core's current behavior of ignoring what it doesn't understand.

Signed-off-by: Martin Brandenburg <martin@omnibond.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index b9da9a0281c9..3e484a667340 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -33,6 +33,7 @@ static const match_table_t tokens = {
 	{ Opt_err,	NULL }
 };
 
+uint64_t orangefs_features;
 
 static int parse_mount_options(struct super_block *sb, char *options,
 		int silent)
@@ -249,6 +250,19 @@ int orangefs_remount(struct orangefs_sb_info_s *orangefs_sb)
 	}
 
 	op_release(new_op);
+
+	if (orangefs_userspace_version >= 20906) {
+		new_op = op_alloc(ORANGEFS_VFS_OP_FEATURES);
+		if (!new_op)
+			return -ENOMEM;
+		new_op->upcall.req.features.features = 0;
+		ret = service_operation(new_op, "orangefs_features", 0);
+		orangefs_features = new_op->downcall.resp.features.features;
+		op_release(new_op);
+	} else {
+		orangefs_features = 0;
+	}
+
 	return ret;
 }
 
@@ -492,6 +506,19 @@ struct dentry *orangefs_mount(struct file_system_type *fst,
 	list_add_tail(&ORANGEFS_SB(sb)->list, &orangefs_superblocks);
 	spin_unlock(&orangefs_superblocks_lock);
 	op_release(new_op);
+
+	if (orangefs_userspace_version >= 20906) {
+		new_op = op_alloc(ORANGEFS_VFS_OP_FEATURES);
+		if (!new_op)
+			return ERR_PTR(-ENOMEM);
+		new_op->upcall.req.features.features = 0;
+		ret = service_operation(new_op, "orangefs_features", 0);
+		orangefs_features = new_op->downcall.resp.features.features;
+		op_release(new_op);
+	} else {
+		orangefs_features = 0;
+	}
+
 	return dget(sb->s_root);
 
 free_op: