Btrfs: add a device id to device items

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 454eb88..ef3583c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -91,10 +91,12 @@
 	__le64 total_blocks;
 	__le64 blocks_used;
 	__le64 root_dir_objectid;
+	__le64 last_device_id;
 	/* fields below here vary with the underlying disk */
 	__le64 device_block_start;
 	__le64 device_num_blocks;
 	__le64 device_root;
+	__le64 device_id;
 } __attribute__ ((__packed__));
 
 /*
@@ -230,6 +232,7 @@
 
 struct btrfs_device_item {
 	__le16 pathlen;
+	__le64 device_id;
 } __attribute__ ((__packed__));
 
 struct crypto_hash;
@@ -798,6 +801,28 @@
 	s->root_dir_objectid = cpu_to_le64(val);
 }
 
+static inline u64 btrfs_super_last_device_id(struct btrfs_super_block *s)
+{
+	return le64_to_cpu(s->last_device_id);
+}
+
+static inline void btrfs_set_super_last_device_id(struct btrfs_super_block *s,
+						  u64 val)
+{
+	s->last_device_id = cpu_to_le64(val);
+}
+
+static inline u64 btrfs_super_device_id(struct btrfs_super_block *s)
+{
+	return le64_to_cpu(s->device_id);
+}
+
+static inline void btrfs_set_super_device_id(struct btrfs_super_block *s,
+						  u64 val)
+{
+	s->device_id = cpu_to_le64(val);
+}
+
 static inline u64 btrfs_super_device_block_start(struct btrfs_super_block *s)
 {
 	return le64_to_cpu(s->device_block_start);
@@ -910,6 +935,17 @@
 	d->pathlen = cpu_to_le16(val);
 }
 
+static inline u64 btrfs_device_id(struct btrfs_device_item *d)
+{
+	return le64_to_cpu(d->device_id);
+}
+
+static inline void btrfs_set_device_id(struct btrfs_device_item *d,
+						u64 val)
+{
+	d->device_id = cpu_to_le64(val);
+}
+
 static inline struct btrfs_root *btrfs_sb(struct super_block *sb)
 {
 	return sb->s_fs_info;