[PATCH 5/6 resend] statfs: add ST_SLAVE

[Christian Brauner <christian.brauner@ubuntu.com>]

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 fs/statfs.c            | 10 +++++++++-
 include/linux/statfs.h |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/statfs.c b/fs/statfs.c
index 2fc6f9c3793c..35ad0402c9a3 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -10,6 +10,7 @@
 #include <linux/uaccess.h>
 #include <linux/compat.h>
 #include "internal.h"
+#include "pnode.h"
 
 static int flags_by_mnt(int mnt_flags)
 {
@@ -50,8 +51,15 @@ static int flags_by_sb(int s_flags)
 
 static int calculate_f_flags(struct vfsmount *mnt)
 {
-	return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
+	int flags = 0;
+
+	flags = ST_VALID | flags_by_mnt(mnt->mnt_flags) |
 		flags_by_sb(mnt->mnt_sb->s_flags);
+
+	if (IS_MNT_SLAVE(real_mount(mnt)))
+		flags |= ST_SLAVE;
+
+	return flags;
 }
 
 static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
diff --git a/include/linux/statfs.h b/include/linux/statfs.h
index 5416b2936dd9..048127effaad 100644
--- a/include/linux/statfs.h
+++ b/include/linux/statfs.h
@@ -41,6 +41,7 @@ struct kstatfs {
 #define ST_NODIRATIME	(1<<11) /* do not update directory access times */
 #define ST_RELATIME	(1<<12) /* update atime relative to mtime/ctime */
 #define ST_UNBINDABLE	(1<<17)	/* change to unbindable */
+#define ST_SLAVE	(1<<19)	/* change to slave */
 #define ST_SHARED	(1<<20)	/* change to shared */
 
 #endif
-- 
2.17.0