Rework error handling in zpool_trim()

When a manual trim is run against an entire pool, errors about
particular devices which don't support trim are suppressed. This changes
zpool_trim() in libzfs so that it doesn't return an error when the only
errors are suppressed ones. An exception is made when none of the
devices support trim, in which case an error is reported and a non-zero
status is returned.

This also fixes how the --wait flag works in the presence of suppressed
errors. In particular, suppressed errors no longer cause zpool_trim()
to skip the wait.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: John Gallagher <john.gallagher@delphix.com>
Closes openzfs#10263 
Closes openzfs#10372 
(cherry picked from commit 50ff632)

lib/libzfs/libzfs_pool.c

@@ -2277,49 +2277,25 @@ zpool_trim_wait(zpool_handle_t *zhp, nvlist_t *vdev_guids)
 }
 
 /*
- * Begin, suspend, or cancel the TRIM (discarding of all free blocks) for
- * the given vdevs in the given pool.
+ * Check errlist and report any errors, omitting ones which should be
+ * suppressed. Returns B_TRUE if any errors were reported.
  */
-int
-zpool_trim(zpool_handle_t *zhp, pool_trim_func_t cmd_type, nvlist_t *vds,
-    trimflags_t *trim_flags)
+static boolean_t
+check_trim_errs(zpool_handle_t *zhp, trimflags_t *trim_flags,
+    nvlist_t *guids_to_paths, nvlist_t *vds, nvlist_t *errlist)
 {
-	char msg[1024];
-	int err;
-
-	nvlist_t *vdev_guids = fnvlist_alloc();
-	nvlist_t *guids_to_paths = fnvlist_alloc();
-	nvlist_t *vd_errlist = NULL;
-	nvlist_t *errlist;
 	nvpair_t *elem;
+	boolean_t reported_errs = B_FALSE;
+	int num_vds = 0;
+	int num_suppressed_errs = 0;
 
-	err = zpool_translate_vdev_guids(zhp, vds, vdev_guids,
-	    guids_to_paths, &vd_errlist);
-	if (err == 0) {
-		err = lzc_trim(zhp->zpool_name, cmd_type, trim_flags->rate,
-		    trim_flags->secure, vdev_guids, &errlist);
-		if (err == 0) {
-			if (trim_flags->wait)
-				err = zpool_trim_wait(zhp, vdev_guids);
-
-			fnvlist_free(vdev_guids);
-			fnvlist_free(guids_to_paths);
-			return (err);
-		}
-
-		if (errlist != NULL) {
-			vd_errlist = fnvlist_lookup_nvlist(errlist,
-			    ZPOOL_TRIM_VDEVS);
-		}
-
-		(void) snprintf(msg, sizeof (msg),
-		    dgettext(TEXT_DOMAIN, "operation failed"));
-	} else {
-		verify(vd_errlist != NULL);
+	for (elem = nvlist_next_nvpair(vds, NULL);
+	    elem != NULL; elem = nvlist_next_nvpair(vds, elem)) {
+		num_vds++;
 	}
 
-	for (elem = nvlist_next_nvpair(vd_errlist, NULL);
-	    elem != NULL; elem = nvlist_next_nvpair(vd_errlist, elem)) {
+	for (elem = nvlist_next_nvpair(errlist, NULL);
+	    elem != NULL; elem = nvlist_next_nvpair(errlist, elem)) {
 		int64_t vd_error = xlate_trim_err(fnvpair_value_int64(elem));
 		char *path;
 
@@ -2331,9 +2307,11 @@ zpool_trim(zpool_handle_t *zhp, pool_trim_func_t cmd_type, nvlist_t *vds,
 		if (vd_error == EZFS_TRIM_NOTSUP &&
 		    trim_flags->fullpool &&
 		    !trim_flags->secure) {
+			num_suppressed_errs++;
 			continue;
 		}
 
+		reported_errs = B_TRUE;
 		if (nvlist_lookup_string(guids_to_paths, nvpair_name(elem),
 		    &path) != 0)
 			path = nvpair_name(elem);
@@ -2342,15 +2320,72 @@ zpool_trim(zpool_handle_t *zhp, pool_trim_func_t cmd_type, nvlist_t *vds,
 		    "cannot trim '%s'", path);
 	}
 
-	fnvlist_free(vdev_guids);
-	fnvlist_free(guids_to_paths);
+	if (num_suppressed_errs == num_vds) {
+		(void) zfs_error_aux(zhp->zpool_hdl, dgettext(TEXT_DOMAIN,
+		    "no devices in pool support trim operations"));
+		(void) (zfs_error(zhp->zpool_hdl, EZFS_TRIM_NOTSUP,
+		    dgettext(TEXT_DOMAIN, "cannot trim")));
+		reported_errs = B_TRUE;
+	}
 
-	if (vd_errlist != NULL) {
-		fnvlist_free(vd_errlist);
-		return (-1);
+	return (reported_errs);
+}
+
+/*
+ * Begin, suspend, or cancel the TRIM (discarding of all free blocks) for
+ * the given vdevs in the given pool.
+ */
+int
+zpool_trim(zpool_handle_t *zhp, pool_trim_func_t cmd_type, nvlist_t *vds,
+    trimflags_t *trim_flags)
+{
+	int err;
+	int retval = 0;
+
+	nvlist_t *vdev_guids = fnvlist_alloc();
+	nvlist_t *guids_to_paths = fnvlist_alloc();
+	nvlist_t *errlist = NULL;
+
+	err = zpool_translate_vdev_guids(zhp, vds, vdev_guids,
+	    guids_to_paths, &errlist);
+	if (err != 0) {
+		check_trim_errs(zhp, trim_flags, guids_to_paths, vds, errlist);
+		retval = -1;
+		goto out;
+	}
+
+	err = lzc_trim(zhp->zpool_name, cmd_type, trim_flags->rate,
+	    trim_flags->secure, vdev_guids, &errlist);
+	if (err != 0) {
+		nvlist_t *vd_errlist;
+		if (errlist != NULL && nvlist_lookup_nvlist(errlist,
+		    ZPOOL_TRIM_VDEVS, &vd_errlist) == 0) {
+			if (check_trim_errs(zhp, trim_flags, guids_to_paths,
+			    vds, vd_errlist)) {
+				retval = -1;
+				goto out;
+			}
+		} else {
+			char msg[1024];
+
+			(void) snprintf(msg, sizeof (msg),
+			    dgettext(TEXT_DOMAIN, "operation failed"));
+			zpool_standard_error(zhp->zpool_hdl, err, msg);
+			retval = -1;
+			goto out;
+		}
 	}
 
-	return (zpool_standard_error(zhp->zpool_hdl, err, msg));
+
+	if (trim_flags->wait)
+		retval = zpool_trim_wait(zhp, vdev_guids);
+
+out:
+	if (errlist != NULL)
+		fnvlist_free(errlist);
+	fnvlist_free(vdev_guids);
+	fnvlist_free(guids_to_paths);
+	return (retval);
 }
 
 /*