Re: [PATCH] disallow create or grow clustered bitmap with writemostly set

[pg@xxxxxxxxxxxxxxxxxxxxxx (Peter Grandi)]

[...]
> +				if (dv->writemostly == FlagSet) {
> +					if (major_num == BITMAP_MAJOR_CLUSTERED) {
> +						pr_err("Can not set --write-mostly with a clustered bitmap\n");
> +						goto abort_locked;
[...]
> +			if (((disk.state & (1 << MD_DISK_WRITEMOSTLY)) == 0) &&
> +			   (strcmp(s->bitmap_file, "clustered") == 0)) {
> +				pr_err("disks marked write-mostly are not supported with clustered bitmap\n");
> +				return 1;

It would be more useful for those error messages to give some
information identifying the MD set and disk, as written they are
only slightly better variants of the classic "Cannot open file."
message.