dm log: remove incorrect field from userspace table output

The output of 'dmsetup table' includes an internal field that should not
be there.  This patch removes it.  To make the fix simpler, we first
reorder a constructor argument

The 'device size' argument is generated internally.  Currently it is
placed as the last space-separated word of the constructor string.
However, we need to use a version of the string without this word, so we
move it to the beginning instead so it is trivial to skip past it.

We keep a copy of the arguments passed to userspace for creating a log,
just in case we need to resend them.  These are the same arguments that
are desired in the STATUSTYPE_TABLE request, except for one.  When
creating the userspace log, the userspace daemon must know the size of
the mirror, so that is added to the arguments given in the constructor
table.  We were printing this extra argument out as well, which is a
mistake.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/dm-log-userspace-base.c

@@ -111,10 +111,9 @@ static int build_constructor_string(struct dm_target *ti,
 		return -ENOMEM;
 	}
 
-	for (i = 0, str_size = 0; i < argc; i++)
-		str_size += sprintf(str + str_size, "%s ", argv[i]);
-	str_size += sprintf(str + str_size, "%llu",
-			    (unsigned long long)ti->len);
+	str_size = sprintf(str, "%llu", (unsigned long long)ti->len);
+	for (i = 0; i < argc; i++)
+		str_size += sprintf(str + str_size, " %s", argv[i]);
 
 	*ctr_str = str;
 	return str_size;
@@ -561,6 +560,7 @@ static int userspace_status(struct dm_dirty_log *log, status_type_t status_type,
 			    char *result, unsigned maxlen)
 {
 	int r = 0;
+	char *table_args;
 	size_t sz = (size_t)maxlen;
 	struct log_c *lc = log->context;
 
@@ -577,8 +577,12 @@ static int userspace_status(struct dm_dirty_log *log, status_type_t status_type,
 		break;
 	case STATUSTYPE_TABLE:
 		sz = 0;
-		DMEMIT("%s %u %s %s ", log->type->name, lc->usr_argc + 1,
-		       lc->uuid, lc->usr_argv_str);
+		table_args = strstr(lc->usr_argv_str, " ");
+		BUG_ON(!table_args); /* There will always be a ' ' */
+		table_args++;
+
+		DMEMIT("%s %u %s %s ", log->type->name, lc->usr_argc,
+		       lc->uuid, table_args);
 		break;
 	}
 	return (r) ? 0 : (int)sz;