4171 clean up spa_feature_*() interfaces

4172 implement extensible_dataset feature for use by other zpool features
Reviewed by: Max Grossman <max.grossman@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Approved by: Garrett D'Amore <garrett@damore.org>

2 files changed, 31 insertions, 32 deletions

diff --git a/usr/src/common/zfs/zfeature_common.c b/usr/src/common/zfs/zfeature_common.c
index dbd3681547..175f8a51c2 100644
--- a/usr/src/common/zfs/zfeature_common.c
+++ b/usr/src/common/zfs/zfeature_common.c
@@ -92,32 +92,22 @@ zfeature_is_supported(const char *guid)
 	if (zfeature_checks_disable)
 		return (B_TRUE);
 
-	return (0 == zfeature_lookup_guid(guid, NULL));
-}
-
-int
-zfeature_lookup_guid(const char *guid, zfeature_info_t **res)
-{
-	for (int i = 0; i < SPA_FEATURES; i++) {
+	for (spa_feature_t i = 0; i < SPA_FEATURES; i++) {
 		zfeature_info_t *feature = &spa_feature_table[i];
-		if (strcmp(guid, feature->fi_guid) == 0) {
-			if (res != NULL)
-				*res = feature;
-			return (0);
-		}
+		if (strcmp(guid, feature->fi_guid) == 0)
+			return (B_TRUE);
 	}
-
-	return (ENOENT);
+	return (B_FALSE);
 }
 
 int
-zfeature_lookup_name(const char *name, zfeature_info_t **res)
+zfeature_lookup_name(const char *name, spa_feature_t *res)
 {
-	for (int i = 0; i < SPA_FEATURES; i++) {
+	for (spa_feature_t i = 0; i < SPA_FEATURES; i++) {
 		zfeature_info_t *feature = &spa_feature_table[i];
 		if (strcmp(name, feature->fi_uname) == 0) {
 			if (res != NULL)
-				*res = feature;
+				*res = i;
 			return (0);
 		}
 	}
@@ -126,11 +116,12 @@ zfeature_lookup_name(const char *name, zfeature_info_t **res)
 }
 
 static void
-zfeature_register(int fid, const char *guid, const char *name, const char *desc,
-    boolean_t readonly, boolean_t mos, zfeature_info_t **deps)
+zfeature_register(spa_feature_t fid, const char *guid, const char *name,
+    const char *desc, boolean_t readonly, boolean_t mos,
+    const spa_feature_t *deps)
 {
 	zfeature_info_t *feature = &spa_feature_table[fid];
-	static zfeature_info_t *nodeps[] = { NULL };
+	static spa_feature_t nodeps[] = { SPA_FEATURE_NONE };
 
 	ASSERT(name != NULL);
 	ASSERT(desc != NULL);
@@ -141,6 +132,7 @@ zfeature_register(int fid, const char *guid, const char *name, const char *desc,
 	if (deps == NULL)
 		deps = nodeps;
 
+	feature->fi_feature = fid;
 	feature->fi_guid = guid;
 	feature->fi_uname = name;
 	feature->fi_desc = desc;
@@ -167,4 +159,8 @@ zpool_feature_init(void)
 	zfeature_register(SPA_FEATURE_SPACEMAP_HISTOGRAM,
 	    "com.delphix:spacemap_histogram", "spacemap_histogram",
 	    "Spacemaps maintain space histograms.", B_TRUE, B_FALSE, NULL);
+	zfeature_register(SPA_FEATURE_EXTENSIBLE_DATASET,
+	    "com.delphix:extensible_dataset", "extensible_dataset",
+	    "Enhanced dataset functionality, used by other features.",
+	    B_FALSE, B_FALSE, NULL);
 }
diff --git a/usr/src/common/zfs/zfeature_common.h b/usr/src/common/zfs/zfeature_common.h
index 5f1abf2ecc..861f1db0fd 100644
--- a/usr/src/common/zfs/zfeature_common.h
+++ b/usr/src/common/zfs/zfeature_common.h
@@ -38,35 +38,38 @@ extern "C" {
 
 struct zfeature_info;
 
+typedef enum spa_feature {
+	SPA_FEATURE_NONE = -1,
+	SPA_FEATURE_ASYNC_DESTROY,
+	SPA_FEATURE_EMPTY_BPOBJ,
+	SPA_FEATURE_LZ4_COMPRESS,
+	SPA_FEATURE_MULTI_VDEV_CRASH_DUMP,
+	SPA_FEATURE_SPACEMAP_HISTOGRAM,
+	SPA_FEATURE_EXTENSIBLE_DATASET,
+	SPA_FEATURES
+} spa_feature_t;
+
 typedef struct zfeature_info {
+	spa_feature_t fi_feature;
 	const char *fi_uname;	/* User-facing feature name */
 	const char *fi_guid;	/* On-disk feature identifier */
 	const char *fi_desc;	/* Feature description */
 	boolean_t fi_can_readonly; /* Can open pool readonly w/o support? */
 	boolean_t fi_mos;	/* Is the feature necessary to read the MOS? */
-	struct zfeature_info **fi_depends; /* array; null terminated */
+	/* array of dependencies, terminated by SPA_FEATURE_NONE */
+	const spa_feature_t *fi_depends;
 } zfeature_info_t;
 
 typedef int (zfeature_func_t)(zfeature_info_t *fi, void *arg);
 
 #define	ZFS_FEATURE_DEBUG
 
-enum spa_feature {
-	SPA_FEATURE_ASYNC_DESTROY,
-	SPA_FEATURE_EMPTY_BPOBJ,
-	SPA_FEATURE_LZ4_COMPRESS,
-	SPA_FEATURE_MULTI_VDEV_CRASH_DUMP,
-	SPA_FEATURE_SPACEMAP_HISTOGRAM,
-	SPA_FEATURES
-} spa_feature_t;
-
 extern zfeature_info_t spa_feature_table[SPA_FEATURES];
 
 extern boolean_t zfeature_is_valid_guid(const char *);
 
 extern boolean_t zfeature_is_supported(const char *);
-extern int zfeature_lookup_guid(const char *, zfeature_info_t **res);
-extern int zfeature_lookup_name(const char *, zfeature_info_t **res);
+extern int zfeature_lookup_name(const char *name, spa_feature_t *res);
 
 extern void zpool_feature_init(void);