From: Jeff Mahoney <jeffm@suse.com>
Subject: btrfs: provide super_operations->inode_get_dev
References: bsc#927455
Patch-mainline: Never, rejected,
 upstream solutions have been met with heavy resistance in
 preference of unworkable fixes

In order to ensure that the per-subvolume anonymous dev_t gets published
to userspace, we need to provide the super_operations->get_inode_dev
operation.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
---
 fs/btrfs/btrfs_inode.h |    2 +-
 fs/btrfs/super.c       |    6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -211,7 +211,7 @@ struct btrfs_inode {
 
 extern unsigned char btrfs_filetype_table[];
 
-static inline struct btrfs_inode *BTRFS_I(struct inode *inode)
+static inline struct btrfs_inode *BTRFS_I(const struct inode *inode)
 {
 	return container_of(inode, struct btrfs_inode, vfs_inode);
 }
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2260,6 +2260,11 @@ static int btrfs_show_devname(struct seq
 	return 0;
 }
 
+static dev_t btrfs_get_inode_dev(const struct inode *inode)
+{
+	return BTRFS_I(inode)->root->anon_dev;
+}
+
 static const struct super_operations btrfs_super_ops = {
 	.drop_inode	= btrfs_drop_inode,
 	.evict_inode	= btrfs_evict_inode,
@@ -2274,6 +2279,7 @@ static const struct super_operations btr
 	.remount_fs	= btrfs_remount,
 	.freeze_fs	= btrfs_freeze,
 	.unfreeze_fs	= btrfs_unfreeze,
+	.get_inode_dev	= btrfs_get_inode_dev,
 };
 
 static const struct file_operations btrfs_ctl_fops = {