+/*
+ * Find a mirror vdev in the source nvlist.
+ *
+ * The mchild array contains a list of disks in one of the top-level mirrors
+ * of the source pool. The schild array contains a list of disks that the
+ * user specified on the command line. We loop over the mchild array to
+ * see if any entry in the schild array matches.
+ *
+ * If a disk in the mchild array is found in the schild array, we return
+ * the index of that entry. Otherwise we return -1.
+ */
+static int
+find_vdev_entry(zpool_handle_t *zhp, nvlist_t **mchild, uint_t mchildren,
+ nvlist_t **schild, uint_t schildren)
+{
+ uint_t mc;
+
+ for (mc = 0; mc < mchildren; mc++) {
+ uint_t sc;
+ char *mpath = zpool_vdev_name(zhp->zpool_hdl, zhp,
+ mchild[mc], B_FALSE);
+
+ for (sc = 0; sc < schildren; sc++) {
+ char *spath = zpool_vdev_name(zhp->zpool_hdl, zhp,
+ schild[sc], B_FALSE);
+ boolean_t result = (strcmp(mpath, spath) == 0);
+
+ free(spath);
+ if (result) {
+ free(mpath);
+ return (mc);
+ }
+ }
+
+ free(mpath);
+ }
+
+ return (-1);
+}
+
+/*
+ * Split a mirror pool. If newroot points to null, then a new nvlist
+ * is generated and it is the responsibility of the caller to free it.
+ */
+int
+zpool_vdev_split(zpool_handle_t *zhp, char *newname, nvlist_t **newroot,
+ nvlist_t *props, splitflags_t flags)
+{
+ zfs_cmd_t zc = { "\0", "\0", "\0", "\0", 0 };
+ char msg[1024];
+ nvlist_t *tree, *config, **child, **newchild, *newconfig = NULL;
+ nvlist_t **varray = NULL, *zc_props = NULL;
+ uint_t c, children, newchildren, lastlog = 0, vcount, found = 0;
+ libzfs_handle_t *hdl = zhp->zpool_hdl;
+ uint64_t vers;
+ boolean_t freelist = B_FALSE, memory_err = B_TRUE;
+ int retval = 0;
+
+ (void) snprintf(msg, sizeof (msg),
+ dgettext(TEXT_DOMAIN, "Unable to split %s"), zhp->zpool_name);
+
+ if (!zpool_name_valid(hdl, B_FALSE, newname))
+ return (zfs_error(hdl, EZFS_INVALIDNAME, msg));
+
+ if ((config = zpool_get_config(zhp, NULL)) == NULL) {
+ (void) fprintf(stderr, gettext("Internal error: unable to "
+ "retrieve pool configuration\n"));
+ return (-1);
+ }
+
+ verify(nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &tree)
+ == 0);
+ verify(nvlist_lookup_uint64(config, ZPOOL_CONFIG_VERSION, &vers) == 0);
+
+ if (props) {
+ prop_flags_t flags = { .create = B_FALSE, .import = B_TRUE };
+ if ((zc_props = zpool_valid_proplist(hdl, zhp->zpool_name,
+ props, vers, flags, msg)) == NULL)
+ return (-1);
+ }
+
+ if (nvlist_lookup_nvlist_array(tree, ZPOOL_CONFIG_CHILDREN, &child,
+ &children) != 0) {
+ zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
+ "Source pool is missing vdev tree"));
+ if (zc_props)
+ nvlist_free(zc_props);
+ return (-1);
+ }
+
+ varray = zfs_alloc(hdl, children * sizeof (nvlist_t *));
+ vcount = 0;
+
+ if (*newroot == NULL ||
+ nvlist_lookup_nvlist_array(*newroot, ZPOOL_CONFIG_CHILDREN,
+ &newchild, &newchildren) != 0)
+ newchildren = 0;
+
+ for (c = 0; c < children; c++) {
+ uint64_t is_log = B_FALSE, is_hole = B_FALSE;
+ char *type;
+ nvlist_t **mchild, *vdev;
+ uint_t mchildren;
+ int entry;
+
+ /*
+ * Unlike cache & spares, slogs are stored in the
+ * ZPOOL_CONFIG_CHILDREN array. We filter them out here.
+ */
+ (void) nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_IS_LOG,
+ &is_log);
+ (void) nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_IS_HOLE,
+ &is_hole);
+ if (is_log || is_hole) {
+ /*
+ * Create a hole vdev and put it in the config.
+ */
+ if (nvlist_alloc(&vdev, NV_UNIQUE_NAME, 0) != 0)
+ goto out;
+ if (nvlist_add_string(vdev, ZPOOL_CONFIG_TYPE,
+ VDEV_TYPE_HOLE) != 0)
+ goto out;
+ if (nvlist_add_uint64(vdev, ZPOOL_CONFIG_IS_HOLE,
+ 1) != 0)
+ goto out;
+ if (lastlog == 0)
+ lastlog = vcount;
+ varray[vcount++] = vdev;
+ continue;
+ }
+ lastlog = 0;
+ verify(nvlist_lookup_string(child[c], ZPOOL_CONFIG_TYPE, &type)
+ == 0);
+ if (strcmp(type, VDEV_TYPE_MIRROR) != 0) {
+ zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
+ "Source pool must be composed only of mirrors\n"));
+ retval = zfs_error(hdl, EZFS_INVALCONFIG, msg);
+ goto out;
+ }
+
+ verify(nvlist_lookup_nvlist_array(child[c],
+ ZPOOL_CONFIG_CHILDREN, &mchild, &mchildren) == 0);
+
+ /* find or add an entry for this top-level vdev */
+ if (newchildren > 0 &&
+ (entry = find_vdev_entry(zhp, mchild, mchildren,
+ newchild, newchildren)) >= 0) {
+ /* We found a disk that the user specified. */
+ vdev = mchild[entry];
+ ++found;
+ } else {
+ /* User didn't specify a disk for this vdev. */
+ vdev = mchild[mchildren - 1];
+ }
+
+ if (nvlist_dup(vdev, &varray[vcount++], 0) != 0)
+ goto out;
+ }
+
+ /* did we find every disk the user specified? */
+ if (found != newchildren) {
+ zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "Device list must "
+ "include at most one disk from each mirror"));
+ retval = zfs_error(hdl, EZFS_INVALCONFIG, msg);
+ goto out;
+ }
+
+ /* Prepare the nvlist for populating. */
+ if (*newroot == NULL) {
+ if (nvlist_alloc(newroot, NV_UNIQUE_NAME, 0) != 0)
+ goto out;
+ freelist = B_TRUE;
+ if (nvlist_add_string(*newroot, ZPOOL_CONFIG_TYPE,
+ VDEV_TYPE_ROOT) != 0)
+ goto out;
+ } else {
+ verify(nvlist_remove_all(*newroot, ZPOOL_CONFIG_CHILDREN) == 0);
+ }
+
+ /* Add all the children we found */
+ if (nvlist_add_nvlist_array(*newroot, ZPOOL_CONFIG_CHILDREN, varray,
+ lastlog == 0 ? vcount : lastlog) != 0)
+ goto out;
+
+ /*
+ * If we're just doing a dry run, exit now with success.
+ */
+ if (flags.dryrun) {
+ memory_err = B_FALSE;
+ freelist = B_FALSE;
+ goto out;
+ }
+
+ /* now build up the config list & call the ioctl */
+ if (nvlist_alloc(&newconfig, NV_UNIQUE_NAME, 0) != 0)
+ goto out;
+
+ if (nvlist_add_nvlist(newconfig,
+ ZPOOL_CONFIG_VDEV_TREE, *newroot) != 0 ||
+ nvlist_add_string(newconfig,
+ ZPOOL_CONFIG_POOL_NAME, newname) != 0 ||
+ nvlist_add_uint64(newconfig, ZPOOL_CONFIG_VERSION, vers) != 0)
+ goto out;
+
+ /*
+ * The new pool is automatically part of the namespace unless we
+ * explicitly export it.
+ */
+ if (!flags.import)
+ zc.zc_cookie = ZPOOL_EXPORT_AFTER_SPLIT;
+ (void) strlcpy(zc.zc_name, zhp->zpool_name, sizeof (zc.zc_name));
+ (void) strlcpy(zc.zc_string, newname, sizeof (zc.zc_string));
+ if (zcmd_write_conf_nvlist(hdl, &zc, newconfig) != 0)
+ goto out;
+ if (zc_props != NULL && zcmd_write_src_nvlist(hdl, &zc, zc_props) != 0)
+ goto out;
+
+ if (zfs_ioctl(hdl, ZFS_IOC_VDEV_SPLIT, &zc) != 0) {
+ retval = zpool_standard_error(hdl, errno, msg);
+ goto out;
+ }
+
+ freelist = B_FALSE;
+ memory_err = B_FALSE;
+
+out:
+ if (varray != NULL) {
+ int v;
+
+ for (v = 0; v < vcount; v++)
+ nvlist_free(varray[v]);
+ free(varray);
+ }
+ zcmd_free_nvlists(&zc);
+ if (zc_props)
+ nvlist_free(zc_props);
+ if (newconfig)
+ nvlist_free(newconfig);
+ if (freelist) {
+ nvlist_free(*newroot);
+ *newroot = NULL;
+ }
+
+ if (retval != 0)
+ return (retval);
+
+ if (memory_err)
+ return (no_memory(hdl));
+
+ return (0);
+}
+