Re: [PATCH 07/20] bcache: add initial data structures for nvm pages

+struct bch_nvm_pgalloc_recs {
+union {
+	struct {
+		struct bch_nvm_pages_owner_head	*owner;
+		struct bch_nvm_pgalloc_recs	*next;
+		__u8				magic[16];
+		__u8				owner_uuid[16];
+		__u32				size;
+		__u32				used;
+		__u64				_pad[4];
+		struct bch_pgalloc_rec		recs[];
+	};
+	__u8	pad[8192];
+};
+};

+struct bch_nvm_pages_owner_head {
+	__u8			uuid[16];
+	char			label[BCH_NVM_PAGES_LABEL_SIZE];
+	/* Per-namespace own lists */
+	struct bch_nvm_pgalloc_recs	*recs[BCH_NVM_PAGES_NAMESPACES_MAX];
+};

+/* heads[0] is always for nvm_pages internal usage */
+struct bch_owner_list_head {
+union {
+	struct {
+		__u32				size;
+		__u32				used;
+		__u64				_pad[4];
+		struct bch_nvm_pages_owner_head	heads[];
+	};
+	__u8	pad[8192];
+};
+};

+#define BCH_MAX_OWNER_LIST				\
+	((sizeof(struct bch_owner_list_head) -		\
+	 offsetof(struct bch_owner_list_head, heads)) /	\
+	 sizeof(struct bch_nvm_pages_owner_head))
+
+/* The on-media bit order is local CPU order */
+struct bch_nvm_pages_sb {
+	__u64			csum;
+	__u64			ns_start;
+	__u64			sb_offset;
+	__u64			version;
+	__u8			magic[16];
+	__u8			uuid[16];
+	__u32			page_size;
+	__u32			total_namespaces_nr;
+	__u32			this_namespace_nr;
+	union {
+		__u8		set_uuid[16];
+		__u64		set_magic;
+	};

+
+	__u64			flags;
+	__u64			seq;
+
+	__u64			feature_compat;
+	__u64			feature_incompat;
+	__u64			feature_ro_compat;
+
+	/* For allocable nvm pages from buddy systems */
+	__u64			pages_offset;
+	__u64			pages_total;
+
+	__u64			pad[8];
+
+	/* Only on the first name space */
+	struct bch_owner_list_head	*owner_list_head;