From 3e43b4573d5d8ff638b36d5524eacfe6e65215b7 Mon Sep 17 00:00:00 2001
From: Dmitri Rubinstein <dmitri.rubinstein@googlemail.com>
Date: Wed, 15 Mar 2017 16:06:54 +0100
Subject: [PATCH] Added fix for Kubernetes btrfs issue #38337

https://github.com/kubernetes/kubernetes/issues/38337
---
 fs/fs.go | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/fs/fs.go b/fs/fs.go
index b78a2e56..950a2eec 100644
--- a/fs/fs.go
+++ b/fs/fs.go
@@ -149,6 +149,31 @@ func processMounts(mounts []*mount.Info, excludedMountpointPrefixes []string) ma
 			continue
 		}
 
+		// btrfs fix: following workaround fixes wrong btrfs Major and Minor Ids reported in /proc/self/mountinfo.
+		// instead of using values from /proc/self/mountinfo we use stat to get Ids from btrfs mount point
+		if mount.Fstype == "btrfs" && mount.Major == 0 && strings.HasPrefix(mount.Source, "/dev/") {
+
+			buf := new(syscall.Stat_t)
+			err := syscall.Stat(mount.Source, buf)
+			if err != nil {
+				glog.Warningf("stat failed on %s with error: %s", mount.Source, err)
+			} else {
+				glog.Infof("btrfs mount %#v", mount)
+				if buf.Mode&syscall.S_IFMT == syscall.S_IFBLK {
+					err := syscall.Stat(mount.Mountpoint, buf)
+					if err != nil {
+						glog.Warningf("stat failed on %s with error: %s", mount.Mountpoint, err)
+					} else {
+						glog.Infof("btrfs dev major:minor %d:%d\n", int(major(buf.Dev)), int(minor(buf.Dev)))
+						glog.Infof("btrfs rdev major:minor %d:%d\n", int(major(buf.Rdev)), int(minor(buf.Rdev)))
+
+						mount.Major = int(major(buf.Dev))
+						mount.Minor = int(minor(buf.Dev))
+					}
+				}
+			}
+		}
+
 		partitions[mount.Source] = partition{
 			fsType:     mount.Fstype,
 			mountpoint: mount.Mountpoint,