Revert "zhack: Add 'feature disable' command"

This reverts commit 83025286175d1ee1c29b842531070f3250a172ba and
ebecfcd6991bebe71511cb8fd409112798f203b2 which broke the build.
While these patches do apply cleanly and passed previous test
runs they need to be updated to account for the changes made in
commit 241b5415748859a3c272fc8f570f2368e93adde9.

Signed-off-by: Brian Behlendorf <[email protected]>
Issue #3878

4 files changed, 6 insertions, 142 deletions

diff --git a/cmd/zhack/zhack.c b/cmd/zhack/zhack.c
index 32d29fd44..eedd17c30 100644
--- a/cmd/zhack/zhack.c
+++ b/cmd/zhack/zhack.c
@@ -58,13 +58,12 @@ libzfs_handle_t *g_zfs;
 static importargs_t g_importargs;
 static char *g_pool;
 static boolean_t g_readonly;
-static boolean_t g_force = B_FALSE;
 
 static void
 usage(void)
 {
 	(void) fprintf(stderr,
-	    "Usage: %s [-c cachefile] [-d dir] [-f] <subcommand> <args> ...\n"
+	    "Usage: %s [-c cachefile] [-d dir] <subcommand> <args> ...\n"
 	    "where <subcommand> <args> is one of the following:\n"
 	    "\n", cmdname);
 
@@ -74,9 +73,6 @@ usage(void)
 	    "    feature enable [-d desc] <pool> <feature>\n"
 	    "        add a new enabled feature to the pool\n"
 	    "        -d <desc> sets the feature's description\n"
-	    "    feature disable <pool> <feature>\n"
-	    "        remove an enabled, but not active, feature\n"
-	    "        from the pool.\n"
 	    "    feature ref [-md] <pool> <feature>\n"
 	    "        change the refcount on the given feature\n"
 	    "        -d decrease instead of increase the refcount\n"
@@ -357,10 +353,8 @@ zhack_do_feature_enable(int argc, char **argv)
 	zhack_spa_open(target, B_FALSE, FTAG, &spa);
 	mos = spa->spa_meta_objset;
 
-	if (zfeature_is_supported(feature.fi_guid) && (g_force == B_FALSE))
-		fatal(spa, FTAG,
-		    "'%s' is a real feature, will not enable\n"
-		    "provide the -f option to force override", feature.fi_guid);
+	if (zfeature_is_supported(feature.fi_guid))
+		fatal(spa, FTAG, "'%s' is a real feature, will not enable");
 	if (0 == zap_contains(mos, spa->spa_feat_desc_obj, feature.fi_guid))
 		fatal(spa, FTAG, "feature already enabled: %s",
 		    feature.fi_guid);
@@ -374,94 +368,6 @@ zhack_do_feature_enable(int argc, char **argv)
 }
 
 static void
-zhack_feature_disable_sync(void *arg, dmu_tx_t *tx)
-{
-	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
-	zfeature_info_t *feature = arg;
-
-	feature_disable_sync(spa, feature, tx);
-
-	spa_history_log_internal(spa, "zhack disable feature", tx,
-	    "name=%s can_readonly=%u",
-	    feature->fi_guid, feature->fi_can_readonly);
-}
-
-static void
-zhack_do_feature_disable(int argc, char **argv)
-{
-	char c;
-	char *target;
-	uint64_t count;
-	spa_t *spa;
-	objset_t *mos;
-	zfeature_info_t feature;
-	spa_feature_t nodeps[] = { SPA_FEATURE_NONE };
-
-	/*
-	 * fi_desc does not matter here because it was written to disk
-	 * when the feature was enabled, but we need to properly set the
-	 * feature for read or write based on the information we read off
-	 * disk later.
-	 */
-	feature.fi_uname = "zhack";
-	feature.fi_mos = B_TRUE;
-	feature.fi_desc = NULL;
-	feature.fi_depends = nodeps;
-	feature.fi_feature = SPA_FEATURE_NONE;
-
-	optind = 1;
-	while ((c = getopt(argc, argv, "")) != -1) {
-		switch (c) {
-		default:
-			usage();
-			break;
-		}
-	}
-	argc -= optind;
-	argv += optind;
-
-	if (argc < 2) {
-		(void) fprintf(stderr, "error: missing feature or pool name\n");
-		usage();
-	}
-	target = argv[0];
-	feature.fi_guid = argv[1];
-
-	if (!zfeature_is_valid_guid(feature.fi_guid))
-		fatal(NULL, FTAG, "invalid feature guid: %s", feature.fi_guid);
-
-	zhack_spa_open(target, B_FALSE, FTAG, &spa);
-	mos = spa->spa_meta_objset;
-
-	if (zfeature_is_supported(feature.fi_guid) && (g_force == B_FALSE)) {
-		fatal(spa, FTAG,
-		    "'%s' is a real feature, will not disable\n"
-		    "provide the -f option to force override", feature.fi_guid);
-	}
-
-	if (0 == zap_contains(mos, spa->spa_feat_for_read_obj,
-	    feature.fi_guid)) {
-		feature.fi_can_readonly = B_FALSE;
-	} else if (0 == zap_contains(mos, spa->spa_feat_for_write_obj,
-	    feature.fi_guid)) {
-		feature.fi_can_readonly = B_TRUE;
-	} else {
-		fatal(spa, FTAG, "feature is not enabled: %s", feature.fi_guid);
-	}
-
-	if (feature_get_refcount_from_disk(spa, &feature, &count) == 0 &&
-	    count > 0) {
-		fatal(spa, FTAG, "feature '%s' is active, can not disable",
-		    feature.fi_guid);
-	}
-
-	VERIFY0(dsl_sync_task(spa_name(spa), NULL,
-	    zhack_feature_disable_sync, &feature, 5, ZFS_SPACE_CHECK_NORMAL));
-
-	spa_close(spa, FTAG);
-}
-
-static void
 feature_incr_sync(void *arg, dmu_tx_t *tx)
 {
 	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
@@ -589,8 +495,6 @@ zhack_do_feature(int argc, char **argv)
 		zhack_do_feature_stat(argc, argv);
 	} else if (strcmp(subcommand, "enable") == 0) {
 		zhack_do_feature_enable(argc, argv);
-	} else if (strcmp(subcommand, "disable") == 0) {
-		zhack_do_feature_disable(argc, argv);
 	} else if (strcmp(subcommand, "ref") == 0) {
 		zhack_do_feature_ref(argc, argv);
 	} else {
@@ -619,7 +523,7 @@ main(int argc, char **argv)
 	dprintf_setup(&argc, argv);
 	zfs_prop_init();
 
-	while ((c = getopt(argc, argv, "c:d:f")) != -1) {
+	while ((c = getopt(argc, argv, "c:d:")) != -1) {
 		switch (c) {
 		case 'c':
 			g_importargs.cachefile = optarg;
@@ -628,9 +532,6 @@ main(int argc, char **argv)
 			assert(g_importargs.paths < MAX_NUM_PATHS);
 			g_importargs.path[g_importargs.paths++] = optarg;
 			break;
-		case 'f':
-			g_force = B_TRUE;
-			break;
 		default:
 			usage();
 			break;
diff --git a/include/sys/zfeature.h b/include/sys/zfeature.h
index 5ea77f847..5abde149a 100644
--- a/include/sys/zfeature.h
+++ b/include/sys/zfeature.h
@@ -63,8 +63,6 @@ extern int feature_get_refcount_from_disk(spa_t *spa, zfeature_info_t *feature,
     uint64_t *res);
 extern void feature_enable_sync(struct spa *, zfeature_info_t *,
     struct dmu_tx *);
-extern void feature_disable_sync(struct spa *, zfeature_info_t *,
-    struct dmu_tx *);
 extern void feature_sync(struct spa *, zfeature_info_t *, uint64_t,
     struct dmu_tx *);
 
diff --git a/lib/libzpool/kernel.c b/lib/libzpool/kernel.c
index f14552374..89e474c65 100644
--- a/lib/libzpool/kernel.c
+++ b/lib/libzpool/kernel.c
@@ -647,6 +647,8 @@ vn_open(char *path, int x1, int flags, int mode, vnode_t **vpp, int x2, int x3)
 #ifdef __linux__
 		flags |= O_DIRECT;
 #endif
+		/* We shouldn't be writing to block devices in userspace */
+		VERIFY(!(flags & FWRITE));
 	}
 
 	if (flags & FCREAT)
diff --git a/module/zfs/zfeature.c b/module/zfs/zfeature.c
index c83b14568..bda954829 100644
--- a/module/zfs/zfeature.c
+++ b/module/zfs/zfeature.c
@@ -380,43 +380,6 @@ feature_enable_sync(spa_t *spa, zfeature_info_t *feature, dmu_tx_t *tx)
 	}
 }
 
-/*
- * This function is non-static for zhack; it should otherwise not be used
- * outside this file.
- */
-void
-feature_disable_sync(spa_t *spa, zfeature_info_t *feature, dmu_tx_t *tx)
-{
-	uint64_t descobj = spa->spa_feat_desc_obj;
-	uint64_t zapobj = feature->fi_can_readonly ?
-	    spa->spa_feat_for_write_obj : spa->spa_feat_for_read_obj;
-
-	ASSERT(0 != zapobj);
-	ASSERT(zfeature_is_valid_guid(feature->fi_guid));
-	ASSERT3U(spa_version(spa), >=, SPA_VERSION_FEATURES);
-
-	if (zap_contains(spa->spa_meta_objset, descobj, feature->fi_guid) == 0)
-		VERIFY0(zap_remove(spa->spa_meta_objset, descobj,
-		    feature->fi_guid, tx));
-
-	if (zap_contains(spa->spa_meta_objset, zapobj, feature->fi_guid) == 0)
-		VERIFY0(zap_remove(spa->spa_meta_objset, zapobj,
-		    feature->fi_guid, tx));
-
-	spa_deactivate_mos_feature(spa, feature->fi_guid);
-
-	if (spa_feature_is_enabled(spa, SPA_FEATURE_ENABLED_TXG)) {
-		uint64_t txgobj = spa->spa_feat_enabled_txg_obj;
-
-		if (txgobj && (zap_contains(spa->spa_meta_objset,
-		    txgobj, feature->fi_guid) == 0)) {
-			spa_feature_decr(spa, SPA_FEATURE_ENABLED_TXG, tx);
-			VERIFY0(zap_remove(spa->spa_meta_objset, txgobj,
-			    feature->fi_guid, tx));
-		}
-	}
-}
-
 static void
 feature_do_action(spa_t *spa, spa_feature_t fid, feature_action_t action,
     dmu_tx_t *tx)