--- utils.c	2015-11-20 01:15:32.227019383 +0100
+++ utils.c	2015-11-20 01:16:59.419971215 +0100
@@ -1208,13 +1208,19 @@ static int resolve_loop_device(const cha
 {
 	int ret;
 	FILE *f;
+	struct stat stat_buf;
 	char fmt[20];
 	char p[PATH_MAX];
 	char real_loop_dev[PATH_MAX];
 
 	if (!realpath(loop_dev, real_loop_dev))
 		return -errno;
-	snprintf(p, PATH_MAX, "/sys/block/%s/loop/backing_file", strrchr(real_loop_dev, '/'));
+
+	if (stat(real_loop_dev, &stat_buf) || !S_ISBLK(stat_buf.st_mode))
+		return -errno;
+
+	snprintf(p, PATH_MAX, "/sys/dev/block/%d:%d/loop/backing_file",
+		major(stat_buf.st_rdev), minor(stat_buf.st_rdev));
 	if (!(f = fopen(p, "r"))) {
 		if (errno == ENOENT)
 			/*
--- mkfs/common.c.orig	2017-03-08 13:23:24.000000000 +0000
+++ mkfs/common.c	2017-03-09 06:24:26.356552024 +0000
@@ -18,6 +18,7 @@
 #include <uuid/uuid.h>
 #include <blkid/blkid.h>
 #include <fcntl.h>
+#include <limits.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "volumes.h"
--- convert/source-ext2.c.orig	2017-03-08 13:23:24.000000000 +0000
+++ convert/source-ext2.c	2017-03-09 06:27:45.991562323 +0000
@@ -16,6 +16,7 @@
 
 #if BTRFSCONVERT_EXT2
 
+#include <linux/limits.h>
 #include "kerncompat.h"
 #include "disk-io.h"
 #include "transaction.h"