zhack: Add repair label option

In case if all label checksums will be invalid on any vdev, the pool will become unimportable. The zhack with newly added cli options could be used to restore label checksums and make pool importable again. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Fedor Uporov <fuporov.vstack@gmail.com> Closes #2510 Closes #12686
2026-05-23 02:44:41 +03:00 · 2021-11-11 11:26:18 -08:00
parent 637771a066
commit d04b5c9e87
7 changed files with 252 additions and 1 deletions
@@ -33,6 +33,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <ctype.h>
+#include <sys/stat.h>
 #include <sys/zfs_context.h>
 #include <sys/spa.h>
 #include <sys/spa_impl.h>
@@ -41,6 +42,7 @@
 #include <sys/zfs_znode.h>
 #include <sys/dsl_synctask.h>
 #include <sys/vdev.h>
+#include <sys/vdev_impl.h>
 #include <sys/fs/zfs.h>
 #include <sys/dmu_objset.h>
 #include <sys/dsl_pool.h>
@@ -76,7 +78,12 @@ usage(void)
 	    "        -d decrease instead of increase the refcount\n"
 	    "        -m add the feature to the label if increasing refcount\n"
 	    "\n"
-	    "    <feature> : should be a feature guid\n");
+	    "    <feature> : should be a feature guid\n"
+	    "\n"
+	    "    label repair <device>\n"
+	    "        repair corrupted label checksums\n"
+	    "\n"
+	    "    <device> : path to vdev\n");
 	exit(1);
 }

@@ -471,6 +478,166 @@ zhack_do_feature(int argc, char **argv)
 	return (0);
 }

+static int
+zhack_repair_label_cksum(int argc, char **argv)
+{
+	zio_checksum_info_t *ci = &zio_checksum_table[ZIO_CHECKSUM_LABEL];
+	const char *cfg_keys[] = { ZPOOL_CONFIG_VERSION,
+	    ZPOOL_CONFIG_POOL_STATE, ZPOOL_CONFIG_GUID };
+	boolean_t labels_repaired[VDEV_LABELS];
+	boolean_t repaired = B_FALSE;
+	vdev_label_t labels[VDEV_LABELS];
+	struct stat st;
+	int fd;
+
+	bzero(labels_repaired, sizeof (labels_repaired));
+	bzero(labels, sizeof (labels));
+
+	abd_init();
+
+	argc -= 1;
+	argv += 1;
+
+	if (argc < 1) {
+		(void) fprintf(stderr, "error: missing device\n");
+		usage();
+	}
+
+	if ((fd = open(argv[0], O_RDWR)) == -1)
+		fatal(NULL, FTAG, "cannot open '%s': %s", argv[0],
+		    strerror(errno));
+
+	if (stat(argv[0], &st) != 0)
+		fatal(NULL, FTAG, "cannot stat '%s': %s", argv[0],
+		    strerror(errno));
+
+	for (int l = 0; l < VDEV_LABELS; l++) {
+		uint64_t label_offset, offset;
+		zio_cksum_t expected_cksum;
+		zio_cksum_t actual_cksum;
+		zio_cksum_t verifier;
+		zio_eck_t *eck;
+		nvlist_t *cfg;
+		int byteswap;
+		uint64_t val;
+		ssize_t err;
+
+		vdev_label_t *vl = &labels[l];
+
+		label_offset = vdev_label_offset(st.st_size, l, 0);
+		err = pread64(fd, vl, sizeof (vdev_label_t), label_offset);
+		if (err == -1) {
+			(void) fprintf(stderr, "error: cannot read "
+			    "label %d: %s\n", l, strerror(errno));
+			continue;
+		} else if (err != sizeof (vdev_label_t)) {
+			(void) fprintf(stderr, "error: bad label %d read size "
+			    "\n", l);
+			continue;
+		}
+
+		err = nvlist_unpack(vl->vl_vdev_phys.vp_nvlist,
+		    VDEV_PHYS_SIZE - sizeof (zio_eck_t), &cfg, 0);
+		if (err) {
+			(void) fprintf(stderr, "error: cannot unpack nvlist "
+			    "label %d\n", l);
+			continue;
+		}
+
+		for (int i = 0; i < ARRAY_SIZE(cfg_keys); i++) {
+			err = nvlist_lookup_uint64(cfg, cfg_keys[i], &val);
+			if (err) {
+				(void) fprintf(stderr, "error: label %d: "
+				    "cannot find nvlist key %s\n",
+				    l, cfg_keys[i]);
+				continue;
+			}
+		}
+
+		void *data = (char *)vl + offsetof(vdev_label_t, vl_vdev_phys);
+		eck = (zio_eck_t *)((char *)(data) + VDEV_PHYS_SIZE) - 1;
+
+		offset = label_offset + offsetof(vdev_label_t, vl_vdev_phys);
+		ZIO_SET_CHECKSUM(&verifier, offset, 0, 0, 0);
+
+		byteswap = (eck->zec_magic == BSWAP_64(ZEC_MAGIC));
+		if (byteswap)
+			byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
+
+		expected_cksum = eck->zec_cksum;
+		eck->zec_cksum = verifier;
+
+		abd_t *abd = abd_get_from_buf(data, VDEV_PHYS_SIZE);
+		ci->ci_func[byteswap](abd, VDEV_PHYS_SIZE, NULL, &actual_cksum);
+		abd_free(abd);
+
+		if (byteswap)
+			byteswap_uint64_array(&expected_cksum,
+			    sizeof (zio_cksum_t));
+
+		if (ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
+			continue;
+
+		eck->zec_cksum = actual_cksum;
+
+		err = pwrite64(fd, data, VDEV_PHYS_SIZE, offset);
+		if (err == -1) {
+			(void) fprintf(stderr, "error: cannot write "
+			    "label %d: %s\n", l, strerror(errno));
+			continue;
+		} else if (err != VDEV_PHYS_SIZE) {
+			(void) fprintf(stderr, "error: bad write size "
+			    "label %d\n", l);
+			continue;
+		}
+
+		fsync(fd);
+
+		labels_repaired[l] = B_TRUE;
+	}
+
+	close(fd);
+
+	abd_fini();
+
+	for (int l = 0; l < VDEV_LABELS; l++) {
+		(void) printf("label %d: %s\n", l,
+		    labels_repaired[l] ? "repaired" : "skipped");
+		repaired |= labels_repaired[l];
+	}
+
+	if (repaired)
+		return (0);
+
+	return (1);
+}
+
+static int
+zhack_do_label(int argc, char **argv)
+{
+	char *subcommand;
+	int err;
+
+	argc--;
+	argv++;
+	if (argc == 0) {
+		(void) fprintf(stderr,
+		    "error: no label operation specified\n");
+		usage();
+	}
+
+	subcommand = argv[0];
+	if (strcmp(subcommand, "repair") == 0) {
+		err = zhack_repair_label_cksum(argc, argv);
+	} else {
+		(void) fprintf(stderr, "error: unknown subcommand: %s\n",
+		    subcommand);
+		usage();
+	}
+
+	return (err);
+}
+
 #define	MAX_NUM_PATHS 1024

 int
@@ -516,6 +683,8 @@ main(int argc, char **argv)

 	if (strcmp(subcommand, "feature") == 0) {
 		rv = zhack_do_feature(argc, argv);
+	} else if (strcmp(subcommand, "label") == 0) {
+		return (zhack_do_label(argc, argv));
 	} else {
 		(void) fprintf(stderr, "error: unknown subcommand: %s\n",
 		    subcommand);