+/**
+ * File IDentifier.
+ *
+ * FID is a cluster-wide unique identifier of a file or an object (stripe).
+ * FIDs are never reused.
+ **/
+struct lu_fid {
+ /**
+ * FID sequence. Sequence is a unit of migration: all files (objects)
+ * with FIDs from a given sequence are stored on the same server.
+ * Lustre should support 2^64 objects, so even if each sequence
+ * has only a single object we can still enumerate 2^64 objects.
+ **/
+ __u64 f_seq;
+ /* FID number within sequence. */
+ __u32 f_oid;
+ /**
+ * FID version, used to distinguish different versions (in the sense
+ * of snapshots, etc.) of the same file system object. Not currently
+ * used.
+ **/
+ __u32 f_ver;
+};
+
+struct filter_fid {
+ struct lu_fid ff_parent; /* ff_parent.f_ver == file stripe number */
+};
+
+/* keep this one for compatibility */
+struct filter_fid_old {
+ struct lu_fid ff_parent;
+ __u64 ff_objid;
+ __u64 ff_seq;
+};
+
+/* Userspace should treat lu_fid as opaque, and only use the following methods
+ * to print or parse them. Other functions (e.g. compare, swab) could be moved
+ * here from lustre_idl.h if needed. */
+typedef struct lu_fid lustre_fid;
+
+/**
+ * Following struct for object attributes, that will be kept inode's EA.
+ * Introduced in 2.0 release (please see b15993, for details)
+ * Added to all objects since Lustre 2.4 as contains self FID
+ */
+struct lustre_mdt_attrs {
+ /**
+ * Bitfield for supported data in this structure. From enum lma_compat.
+ * lma_self_fid and lma_flags are always available.
+ */
+ __u32 lma_compat;
+ /**
+ * Per-file incompat feature list. Lustre version should support all
+ * flags set in this field. The supported feature mask is available in
+ * LMA_INCOMPAT_SUPP.
+ */
+ __u32 lma_incompat;
+ /** FID of this inode */
+ struct lu_fid lma_self_fid;
+};
+
+/**
+ * Prior to 2.4, the LMA structure also included SOM attributes which has since
+ * been moved to a dedicated xattr
+ * lma_flags was also removed because of lma_compat/incompat fields.
+ */
+#define LMA_OLD_SIZE (sizeof(struct lustre_mdt_attrs) + 5 * sizeof(__u64))
+
+/**
+ * OST object IDentifier.
+ */
+struct ost_id {
+ union {
+ struct ostid {
+ __u64 oi_id;
+ __u64 oi_seq;
+ } oi;
+ struct lu_fid oi_fid;
+ };
+};
+
+#define DOSTID LPX64":"LPU64
+#define POSTID(oi) ostid_seq(oi), ostid_id(oi)