Add types to featureflags in zfs

The boolean featureflags in use thus far in ZFS are extremely useful,
but because they take advantage of the zap layer, more interesting data
than just a true/false value can be stored in a featureflag. In redacted
send/receive, this is used to store the list of redaction snapshots for
a redacted dataset.

This change adds the ability for ZFS to store types other than a boolean
in a featureflag. The only other implemented type is a uint64_t array.
It also modifies the interfaces around dataset features to accomodate
the new capabilities, and adds a few new functions to increase
encapsulation.

This functionality will be used by the Redacted Send/Receive feature.

Reviewed-by: Matthew Ahrens <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Paul Dagnelie <[email protected]>
Closes #7981 

1 files changed, 12 insertions, 2 deletions

diff --git a/include/zfeature_common.h b/include/zfeature_common.h
index 84bc7f816..3804d7b1a 100644
--- a/include/zfeature_common.h
+++ b/include/zfeature_common.h
@@ -20,7 +20,7 @@
  */
 
 /*
- * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  * Copyright (c) 2017, Intel Corporation.
@@ -73,7 +73,10 @@ typedef enum spa_feature {
 typedef enum zfeature_flags {
 	/* Can open pool readonly even if this feature is not supported. */
 	ZFEATURE_FLAG_READONLY_COMPAT =		(1 << 0),
-	/* Is this feature necessary to read the MOS? */
+	/*
+	 * Is this feature necessary to load the pool? i.e. do we need this
+	 * feature to read the full feature list out of the MOS?
+	 */
 	ZFEATURE_FLAG_MOS =			(1 << 1),
 	/* Activate this feature at the same time it is enabled. */
 	ZFEATURE_FLAG_ACTIVATE_ON_ENABLE =	(1 << 2),
@@ -81,6 +84,12 @@ typedef enum zfeature_flags {
 	ZFEATURE_FLAG_PER_DATASET =		(1 << 3)
 } zfeature_flags_t;
 
+typedef enum zfeature_type {
+	ZFEATURE_TYPE_BOOLEAN,
+	ZFEATURE_TYPE_UINT64_ARRAY,
+	ZFEATURE_NUM_TYPES
+} zfeature_type_t;
+
 typedef struct zfeature_info {
 	spa_feature_t fi_feature;
 	const char *fi_uname;	/* User-facing feature name */
@@ -88,6 +97,7 @@ typedef struct zfeature_info {
 	const char *fi_desc;	/* Feature description */
 	zfeature_flags_t fi_flags;
 	boolean_t fi_zfs_mod_supported;	/* supported by running zfs module */
+	zfeature_type_t fi_type; /* Only relevant for PER_DATASET features */
 	/* array of dependencies, terminated by SPA_FEATURE_NONE */
 	const spa_feature_t *fi_depends;
 } zfeature_info_t;