Better error messages for broken reshape

mdadm --grow --continue has no functionality to restore critical sectors
if reshape was stopped during operation. This functionality belongs to
assemble or incremental.

This patch adds hints to error messages, to try to reassemble array in
case of reshape failure to restore critical sector, so assemble can
handle restoration.

Signed-off-by: Mateusz Kusiak <[email protected]>

Grow.c

@@ -2387,6 +2387,7 @@ static int verify_reshape_position(struct mdinfo *info, int level)
 			} else if (info->reshape_progress > position) {
 				pr_err("Fatal error: array reshape was not properly frozen (expected reshape position is %llu, but reshape progress is %llu.\n",
 				       position, info->reshape_progress);
+				pr_err("Reassemble array to try to restore critical sector.\n");
 				ret_val = -1;
 			} else {
 				dprintf("Reshape position in md and metadata are the same;");

super-intel.c

@@ -12596,7 +12596,8 @@ static int imsm_manage_reshape(
 		init_migr_record_imsm(st, dev, sra);
 	else {
 		if (__le32_to_cpu(migr_rec->rec_status) != UNIT_SRC_NORMAL) {
-			dprintf("imsm: cannot restart migration when data are present in copy area.\n");
+			pr_err("imsm: Cannot restart migration when data are present in copy area.\n"
+			       "      Reassemble array to try to restore critical sector.\n");
 			goto abort;
 		}
 		/* Save checkpoint to update migration record for current