9  * or https://opensource.org/licenses/CDDL-1.0.
37  * -----------------
39  * ZFS feature flags are used to provide fine-grained versioning to the ZFS
40  * on-disk format. Once enabled on a pool feature flags replace the old
43  * Each new on-disk format change will be given a uniquely identifying string
45  * organizations creating new on-disk formats with the same version number. To
51  * ----------------
59  *      feature, but the feature has not been used yet, so no on-disk
66  * Feature flags makes no differentiation between non-zero reference counts
74  * It is the responsibility of the individual features to maintain a non-zero
78  * ------------
86  * On-disk Format
87  * --------------
91  * SPA_VERSION_BEFORE_FEATURES (28) first, so all pre-feature flags on disk
98  * 1) features_for_read: feature GUID -> reference count
100  * 2) features_for_write: feature GUID -> reference count
102  * 3) feature_descriptions: feature GUID -> descriptive string
108  * To open a pool in read-only mode only the features listed in
111  * To open the pool in read-write mode features in both features_for_read and
126  * -------------------
141  * Features may not perform enable-time initialization. Instead, any such
143  * enforces that on-disk changes be made only when features are used. Code
156  * has made an on-disk format change. Later, after the destroyed dataset's
159  * decremented back to 0 to indicate that it has undone its on-disk format
170  * this software.  Adds each unsupported feature (name -> description) to
177 	objset_t *os = spa->spa_meta_objset;  in spa_features_check()
182 	    spa->spa_feat_for_write_obj : spa->spa_feat_for_read_obj;  in spa_features_check()
193 		ASSERT(za->za_integer_length == sizeof (uint64_t) &&  in spa_features_check()
194 		    za->za_num_integers == 1);  in spa_features_check()
197 			fnvlist_add_uint64(enabled_feat, za->za_name,  in spa_features_check()
198 			    za->za_first_integer);  in spa_features_check()
201 		if (za->za_first_integer != 0 &&  in spa_features_check()
202 		    !zfeature_is_supported(za->za_name)) {  in spa_features_check()
208 				if (zap_lookup(os, spa->spa_feat_desc_obj,  in spa_features_check()
209 				    za->za_name, 1, MAXPATHLEN, buf) == 0)  in spa_features_check()
213 				    za->za_name, desc) == 0);  in spa_features_check()
227  * Use an in-memory cache of feature refcounts for quick retrieval.
229  * Note: well-designed features will not need to use this; they should
231  * However, this is non-static for zdb, zhack, and spa_add_feature_stats().
236 	ASSERT(VALID_FEATURE_FID(feature->fi_feature));  in feature_get_refcount()
237 	if (spa->spa_feat_refcount_cache[feature->fi_feature] ==  in feature_get_refcount()
241 	*res = spa->spa_feat_refcount_cache[feature->fi_feature];  in feature_get_refcount()
246  * Note: well-designed features will not need to use this; they should
248  * However, this is non-static for zdb and zhack.
256 	uint64_t zapobj = (feature->fi_flags & ZFEATURE_FLAG_READONLY_COMPAT) ?  in feature_get_refcount_from_disk()
257 	    spa->spa_feat_for_write_obj : spa->spa_feat_for_read_obj;  in feature_get_refcount_from_disk()
266 	err = zap_lookup(spa->spa_meta_objset, zapobj,  in feature_get_refcount_from_disk()
267 	    feature->fi_guid, sizeof (uint64_t), 1, &refcount);  in feature_get_refcount_from_disk()
282 	uint64_t enabled_txg_obj __maybe_unused = spa->spa_feat_enabled_txg_obj;  in feature_get_enabled_txg()
284 	ASSERT(zfeature_depends_on(feature->fi_feature,  in feature_get_enabled_txg()
287 	if (!spa_feature_is_enabled(spa, feature->fi_feature)) {  in feature_get_enabled_txg()
293 	VERIFY0(zap_lookup(spa->spa_meta_objset, spa->spa_feat_enabled_txg_obj,  in feature_get_enabled_txg()
294 	    feature->fi_guid, sizeof (uint64_t), 1, res));  in feature_get_enabled_txg()
300  * This function is non-static for zhack; it should otherwise not be used
307 	ASSERT(VALID_FEATURE_OR_NONE(feature->fi_feature));  in feature_sync()
308 	uint64_t zapobj = (feature->fi_flags & ZFEATURE_FLAG_READONLY_COMPAT) ?  in feature_sync()
309 	    spa->spa_feat_for_write_obj : spa->spa_feat_for_read_obj;  in feature_sync()
310 	VERIFY0(zap_update(spa->spa_meta_objset, zapobj, feature->fi_guid,  in feature_sync()
320 	if (feature->fi_feature != SPA_FEATURE_NONE) {  in feature_sync()
322 		    &spa->spa_feat_refcount_cache[feature->fi_feature];  in feature_sync()
328 		spa_deactivate_mos_feature(spa, feature->fi_guid);  in feature_sync()
329 	else if (feature->fi_flags & ZFEATURE_FLAG_MOS)  in feature_sync()
330 		spa_activate_mos_feature(spa, feature->fi_guid, tx);  in feature_sync()
334  * This function is non-static for zhack; it should otherwise not be used
341 	    (feature->fi_flags & ZFEATURE_FLAG_ACTIVATE_ON_ENABLE) ? 1 : 0;  in feature_enable_sync()
342 	uint64_t zapobj = (feature->fi_flags & ZFEATURE_FLAG_READONLY_COMPAT) ?  in feature_enable_sync()
343 	    spa->spa_feat_for_write_obj : spa->spa_feat_for_read_obj;  in feature_enable_sync()
346 	ASSERT(zfeature_is_valid_guid(feature->fi_guid));  in feature_enable_sync()
352 	if (zap_contains(spa->spa_meta_objset, zapobj, feature->fi_guid) == 0)  in feature_enable_sync()
355 	for (int i = 0; feature->fi_depends[i] != SPA_FEATURE_NONE; i++)  in feature_enable_sync()
356 		spa_feature_enable(spa, feature->fi_depends[i], tx);  in feature_enable_sync()
358 	VERIFY0(zap_update(spa->spa_meta_objset, spa->spa_feat_desc_obj,  in feature_enable_sync()
359 	    feature->fi_guid, 1, strlen(feature->fi_desc) + 1,  in feature_enable_sync()
360 	    feature->fi_desc, tx));  in feature_enable_sync()
367 		if (spa->spa_feat_enabled_txg_obj == 0ULL) {  in feature_enable_sync()
368 			spa->spa_feat_enabled_txg_obj =  in feature_enable_sync()
369 			    zap_create_link(spa->spa_meta_objset,  in feature_enable_sync()
375 		VERIFY0(zap_add(spa->spa_meta_objset,  in feature_enable_sync()
376 		    spa->spa_feat_enabled_txg_obj, feature->fi_guid,  in feature_enable_sync()
387 	if (spa->spa_errata == ZPOOL_ERRATA_ZOL_8308_ENCRYPTION &&  in feature_enable_sync()
390 	    feature->fi_feature == SPA_FEATURE_BOOKMARK_V2)  in feature_enable_sync()
391 		spa->spa_errata = 0;  in feature_enable_sync()
394 	 * Convert the old on-disk error log to the new format when activating  in feature_enable_sync()
397 	if (feature->fi_feature == SPA_FEATURE_HEAD_ERRLOG)  in feature_enable_sync()
408 	    (feature->fi_flags & ZFEATURE_FLAG_READONLY_COMPAT) ?  in feature_do_action()
409 	    spa->spa_feat_for_write_obj : spa->spa_feat_for_read_obj;  in feature_do_action()
413 	ASSERT(zfeature_is_valid_guid(feature->fi_guid));  in feature_do_action()
427 		refcount--;  in feature_do_action()
444 	ASSERT((!spa->spa_sync_on && tx->tx_txg == TXG_INITIAL) ||  in spa_feature_create_zap_objects()
447 	spa->spa_feat_for_read_obj = zap_create_link(spa->spa_meta_objset,  in spa_feature_create_zap_objects()
450 	spa->spa_feat_for_write_obj = zap_create_link(spa->spa_meta_objset,  in spa_feature_create_zap_objects()
453 	spa->spa_feat_desc_obj = zap_create_link(spa->spa_meta_objset,  in spa_feature_create_zap_objects()