Btrfs-progs print more informative error when we fail to open a device

print more informative error when we fail to open a device

If open() fails, we should let the user know why it failed.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Gene Czarcinski <gene@czarc.net>

utils.c

@@ -1229,7 +1229,8 @@ scan_again:
 
 		fd = open(fullpath, O_RDONLY);
 		if (fd < 0) {
-			fprintf(stderr, "failed to read %s\n", fullpath);
+			fprintf(stderr, "failed to open %s: %s\n",
+				fullpath, strerror(errno));
 			continue;
 		}
 		ret = btrfs_scan_one_device(fd, fullpath, &tmp_devices,