7584 Improve 'zpool labelclear' command

usr/src/cmd/zpool/Makefile

@@ -41,8 +41,12 @@ SRCS += $(STAT_COMMON_SRCS)
 
 LDLIBS += -lzfs -lnvpair -ldevid -lefi -ldiskmgt -luutil -lumem
 
+INCS += -I../../uts/common/fs/zfs
 INCS += -I../../common/zfs -I$(STATCOMMONDIR)
 
+C99MODE=	-xc99=%all
+C99LMODE=	-Xc99=%all
+
 CPPFLAGS += -D_LARGEFILE64_SOURCE=1 -D_REENTRANT $(INCS)
 $(NOT_RELEASE_BUILD)CPPFLAGS += -DDEBUG
 

usr/src/cmd/zpool/zpool_main.c

@@ -36,6 +36,7 @@
 #include <libgen.h>
 #include <libintl.h>
 #include <libuutil.h>
+#include <limits.h>
 #include <locale.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -47,6 +48,7 @@
 #include <zone.h>
 #include <zfs_prop.h>
 #include <sys/fs/zfs.h>
+#include <sys/vdev_impl.h>
 #include <sys/stat.h>
 
 #include <libzfs.h>
@@ -234,7 +236,8 @@ get_usage(zpool_help_t idx)
 		return (gettext("\tiostat [-v] [-T d|u] [pool] ... [interval "
 		    "[count]]\n"));
 	case HELP_LABELCLEAR:
-		return (gettext("\tlabelclear [-f] <vdev>\n"));
+		return (gettext("\tlabelclear [-b | -e | -i index] [-c] [-m] "
+		    "[-f] <vdev>\n"));
 	case HELP_LIST:
 		return (gettext("\tlist [-Hp] [-o property[,...]] "
 		    "[-T d|u] [pool] ... [interval [count]]\n"));
@@ -652,10 +655,39 @@ zpool_do_labelclear(int argc, char **argv)
 	pool_state_t state;
 	boolean_t inuse = B_FALSE;
 	boolean_t force = B_FALSE;
+	boolean_t check = B_FALSE;
+	boolean_t cherry = B_FALSE;
+	unsigned int start = 0, n = VDEV_LABELS;
+	long long index = 0;
+	const char *errstr;
 
 	/* check options */
-	while ((c = getopt(argc, argv, "f")) != -1) {
+	while ((c = getopt(argc, argv, "bei:cmf")) != -1) {
 		switch (c) {
+		case 'b':
+			start = 0;
+			n = VDEV_LABELS / 2;
+			break;
+		case 'e':
+			start = VDEV_LABELS / 2;
+			n = VDEV_LABELS / 2;
+			break;
+		case 'i':
+			index = strtonum(optarg, 0, VDEV_LABELS - 1, &errstr);
+			if(errstr) {
+				(void) fprintf(stderr,
+				    gettext("Invalid index value provided\n"));
+				return (1);
+			}
+			start = (unsigned int)index;
+			n = 1;
+			break;
+		case 'c':
+			check = B_TRUE;
+			break;
+		case 'm':
+			cherry = B_TRUE;
+			break;
 		case 'f':
 			force = B_TRUE;
 			break;
@@ -708,8 +740,12 @@ zpool_do_labelclear(int argc, char **argv)
 	}
 
 	if (zpool_read_label(fd, &config) != 0 || config == NULL) {
-		(void) fprintf(stderr,
-		    gettext("failed to read label from %s\n"), vdev);
+		if (force)
+			goto wipe_label;
+		(void) fprintf(stderr, gettext(
+		    "use '-f' to override the following error:\n"
+		    "failed to read label from \"%s\"\n"),
+		     vdev);
 		return (1);
 	}
 	nvlist_free(config);
@@ -762,7 +798,7 @@ zpool_do_labelclear(int argc, char **argv)
 	}
 
 wipe_label:
-	ret = zpool_clear_label(fd);
+	ret = zpool_clear_n_labels(fd, start, n, check, cherry);
 	if (ret != 0) {
 		(void) fprintf(stderr,
 		    gettext("failed to clear label for %s\n"), vdev);

usr/src/common/nvpair/nvpair.c

@@ -2354,6 +2354,18 @@ nvlist_common(nvlist_t *nvl, char *buf, size_t *buflen, int encoding,
 	return (err);
 }
 
+int
+nvlist_invalidate(char *buf, size_t buflen)
+{
+	if (buf == NULL || buflen < sizeof (nvs_header_t))
+		return (EINVAL);
+
+	nvs_header_t *nvh = (void *)buf;
+	nvh->nvh_encoding = NV_ENCODE_INVALID;
+
+	return (0);
+}
+
 int
 nvlist_size(nvlist_t *nvl, size_t *size, int encoding)
 {

usr/src/lib/libnvpair/mapfile-vers

@@ -243,6 +243,7 @@ SYMBOL_VERSION SUNWprivate_1.1 {
     global:
 	dump_nvlist;
 	nvlist_add_hrtime;
+	nvlist_invalidate;
 	nvlist_lookup_hrtime;
 	nvlist_print;
 	nvlist_print_json;

usr/src/lib/libzfs/common/libzfs.h

@@ -763,6 +763,8 @@ extern int zpool_in_use(libzfs_handle_t *, int, pool_state_t *, char **,
  * Label manipulation.
  */
 extern int zpool_read_label(int, nvlist_t **);
+extern int zpool_clear_n_labels(int, unsigned int, unsigned int, boolean_t,
+    boolean_t);
 extern int zpool_clear_label(int);
 
 /* is this zvol valid for use as a dump device? */

usr/src/lib/libzfs/common/libzfs_import.c

@@ -1063,35 +1063,67 @@ zpool_open_func(void *arg)
 }
 
 /*
- * Given a file descriptor, clear (zero) the label information.
+ * Given a file descriptor, a starting label and a number of labels to clear,
+ * clear (zero) the label information.
  */
 int
-zpool_clear_label(int fd)
+zpool_clear_n_labels(int fd, unsigned int start, unsigned int n,
+    boolean_t check, boolean_t cherry)
 {
 	struct stat64 statbuf;
-	int l;
-	vdev_label_t *label;
+	unsigned int l, end;
+	vdev_label_t label;
 	uint64_t size;
 
+	char *buf = label.vl_vdev_phys.vp_nvlist;
+	size_t buflen = sizeof (label.vl_vdev_phys.vp_nvlist);
+
 	if (fstat64(fd, &statbuf) == -1)
 		return (0);
 	size = P2ALIGN_TYPED(statbuf.st_size, sizeof (vdev_label_t), uint64_t);
 
-	if ((label = calloc(sizeof (vdev_label_t), 1)) == NULL)
+	end = start + n;
+	if (end > VDEV_LABELS)
 		return (-1);
 
-	for (l = 0; l < VDEV_LABELS; l++) {
-		if (pwrite64(fd, label, sizeof (vdev_label_t),
-		    label_offset(size, l)) != sizeof (vdev_label_t)) {
-			free(label);
-			return (-1);
+	for (l = start; l < end; l++) {
+		if (check || cherry) {
+			if (pread64(fd, &label, sizeof (vdev_label_t),
+			    label_offset(size, l)) != sizeof (vdev_label_t))
+				return (-1);
+
+			if (check == B_TRUE) {
+				nvlist_t *config = NULL;
+				if (nvlist_unpack(buf, buflen, &config, 0) != 0)
+					return (-1);
+				nvlist_free(config);
+			}
+		}
+
+		if (cherry == B_TRUE) {
+			if (nvlist_invalidate(buf, buflen) != 0)
+				return (-1);
+		} else {
+			(void) memset(&label, 0, sizeof (vdev_label_t));
 		}
+
+		if (pwrite64(fd, &label, sizeof (vdev_label_t),
+		    label_offset(size, l)) != sizeof (vdev_label_t))
+			return (-1);
 	}
 
-	free(label);
 	return (0);
 }
 
+/*
+ * Given a file descriptor, clear (zero) the label information.
+ */
+int
+zpool_clear_label(int fd)
+{
+	return (zpool_clear_n_labels(fd, 0, VDEV_LABELS, B_FALSE, B_FALSE));
+}
+
 /*
  * Given a list of directories to search, find all pools stored on disk.  This
  * includes partial pools which are not available to import.  If no args are

usr/src/lib/libzfs/common/mapfile-vers

@@ -180,6 +180,7 @@ SYMBOL_VERSION SUNWprivate_1.1 {
 	zfs_zpl_version_map;
 	zpool_add;
 	zpool_clear;
+	zpool_clear_n_labels;
 	zpool_clear_label;
 	zpool_close;
 	zpool_create;

usr/src/man/man1m/zpool.1m

@@ -105,7 +105,8 @@
 .Op Ar interval Op Ar count
 .Nm
 .Cm labelclear
-.Op Fl f
+.Op Fl cfm
+.Op Fl Sy b Ns | Ns Sy e Ns | Ns Sy i Ar index
 .Ar device
 .Nm
 .Cm list
@@ -1275,17 +1276,41 @@ pool, in addition to the pool-wide statistics.
 .It Xo
 .Nm
 .Cm labelclear
-.Op Fl f
+.Op Fl cfm
+.Op Fl Sy b Ns | Ns Sy e Ns | Ns Sy i Ar index
 .Ar device
 .Xc
 Removes ZFS label information from the specified
 .Ar device .
 The
 .Ar device
 must not be part of an active pool configuration.
+Options
+.Fl b ,
+.Fl e
+and
+.Fl i
+can be used for clearing specific labels.
+They are mutually exclusive and the last one will supersede others, if any.
 .Bl -tag -width Ds
+.It Fl c
+Check label integrity before doing anything.
 .It Fl f
 Treat exported or foreign devices as inactive.
+.It Fl m
+Perform minimal operation needed to invalidate a label instead of blindly
+erasing every single byte.
+This reduces (but does not annihilate) the risks of overriding important
+on-disk data.
+.It Fl b
+Only remove ZFS labels located at the beginning of
+.Ar device .
+.It Fl e
+Only remove ZFS labels located at the end of
+.Ar device .
+.It Fl i Ar index
+Remove a single label entry located at position
+.Ar index .
 .El
 .It Xo
 .Nm

usr/src/uts/common/sys/nvpair.h

@@ -98,6 +98,7 @@ typedef struct nvlist {
 #define	NV_VERSION	0
 
 /* nvlist pack encoding */
+#define	NV_ENCODE_INVALID	(-1)
 #define	NV_ENCODE_NATIVE	0
 #define	NV_ENCODE_XDR		1
 
@@ -153,6 +154,7 @@ void nv_alloc_fini(nv_alloc_t *);
 /* list management */
 int nvlist_alloc(nvlist_t **, uint_t, int);
 void nvlist_free(nvlist_t *);
+int nvlist_invalidate(char *, size_t);
 int nvlist_size(nvlist_t *, size_t *, int);
 int nvlist_pack(nvlist_t *, char **, size_t *, int, int);
 int nvlist_unpack(char *, size_t, nvlist_t **, int);