+ __u16 cr_namelen;
+ __u16 cr_flags; /**< \a changelog_rec_flags */
+ __u32 cr_type; /**< \a changelog_rec_type */
+ __u64 cr_index; /**< changelog record number */
+ __u64 cr_prev; /**< last index for this target fid */
+ __u64 cr_time;
+ union {
+ lustre_fid cr_tfid; /**< target fid */
+ __u32 cr_markerflags; /**< CL_MARK flags */
+ };
+ lustre_fid cr_pfid; /**< parent fid */
+};
+
+/* Changelog extension for RENAME. */
+struct changelog_ext_rename {
+ lustre_fid cr_sfid; /**< source fid, or zero */
+ lustre_fid cr_spfid; /**< source parent fid, or zero */
+};
+
+/* Changelog extension to include JOBID. */
+struct changelog_ext_jobid {
+ char cr_jobid[LUSTRE_JOBID_SIZE]; /**< zero-terminated string. */
+};
+
+
+static inline size_t changelog_rec_offset(enum changelog_rec_flags crf)
+{
+ size_t size = sizeof(struct changelog_rec);
+
+ if (crf & CLF_RENAME)
+ size += sizeof(struct changelog_ext_rename);
+
+ if (crf & CLF_JOBID)
+ size += sizeof(struct changelog_ext_jobid);
+
+ return size;
+}
+
+static inline size_t changelog_rec_size(const struct changelog_rec *rec)
+{
+ return changelog_rec_offset(rec->cr_flags);
+}
+
+static inline size_t changelog_rec_varsize(const struct changelog_rec *rec)
+{
+ return changelog_rec_size(rec) - sizeof(*rec) + rec->cr_namelen;
+}
+
+static inline
+struct changelog_ext_rename *changelog_rec_rename(const struct changelog_rec *rec)
+{
+ enum changelog_rec_flags crf = rec->cr_flags & CLF_VERSION;
+
+ return (struct changelog_ext_rename *)((char *)rec +
+ changelog_rec_offset(crf));
+}
+
+/* The jobid follows the rename extension, if present */
+static inline
+struct changelog_ext_jobid *changelog_rec_jobid(const struct changelog_rec *rec)
+{
+ enum changelog_rec_flags crf = rec->cr_flags &
+ (CLF_VERSION | CLF_RENAME);
+
+ return (struct changelog_ext_jobid *)((char *)rec +
+ changelog_rec_offset(crf));
+}
+
+/* The name follows the rename and jobid extensions, if present */
+static inline char *changelog_rec_name(const struct changelog_rec *rec)
+{
+ return (char *)rec + changelog_rec_offset(rec->cr_flags &
+ CLF_SUPPORTED);
+}
+
+static inline size_t changelog_rec_snamelen(const struct changelog_rec *rec)
+{
+ return rec->cr_namelen - strlen(changelog_rec_name(rec)) - 1;
+}
+
+static inline char *changelog_rec_sname(const struct changelog_rec *rec)
+{
+ char *cr_name = changelog_rec_name(rec);
+
+ return cr_name + strlen(cr_name) + 1;
+}
+
+/**
+ * Remap a record to the desired format as specified by the crf flags.
+ * The record must be big enough to contain the final remapped version.
+ * Superfluous extension fields are removed and missing ones are added
+ * and zeroed. The flags of the record are updated accordingly.
+ *
+ * The jobid and rename extensions can be added to a record, to match the
+ * format an application expects, typically. In this case, the newly added
+ * fields will be zeroed.
+ * The Jobid field can be removed, to guarantee compatibility with older
+ * clients that don't expect this field in the records they process.
+ *
+ * The following assumptions are being made:
+ * - CLF_RENAME will not be removed
+ * - CLF_JOBID will not be added without CLF_RENAME being added too
+ *
+ * @param[in,out] rec The record to remap.
+ * @param[in] crf_wanted Flags describing the desired extensions.
+ */
+static inline void changelog_remap_rec(struct changelog_rec *rec,
+ enum changelog_rec_flags crf_wanted)
+{
+ char *jid_mov;
+ char *rnm_mov;
+
+ crf_wanted &= CLF_SUPPORTED;
+
+ if ((rec->cr_flags & CLF_SUPPORTED) == crf_wanted)
+ return;
+
+ /* First move the variable-length name field */
+ memmove((char *)rec + changelog_rec_offset(crf_wanted),
+ changelog_rec_name(rec), rec->cr_namelen);
+
+ /* Locations of jobid and rename extensions in the remapped record */
+ jid_mov = (char *)rec +
+ changelog_rec_offset(crf_wanted & ~CLF_JOBID);
+ rnm_mov = (char *)rec +
+ changelog_rec_offset(crf_wanted & ~(CLF_JOBID | CLF_RENAME));
+
+ /* Move the extension fields to the desired positions */
+ if ((crf_wanted & CLF_JOBID) && (rec->cr_flags & CLF_JOBID))
+ memmove(jid_mov, changelog_rec_jobid(rec),
+ sizeof(struct changelog_ext_jobid));
+
+ if ((crf_wanted & CLF_RENAME) && (rec->cr_flags & CLF_RENAME))
+ memmove(rnm_mov, changelog_rec_rename(rec),
+ sizeof(struct changelog_ext_rename));
+
+ /* Clear newly added fields */
+ if ((crf_wanted & CLF_JOBID) && !(rec->cr_flags & CLF_JOBID))
+ memset(jid_mov, 0, sizeof(struct changelog_ext_jobid));
+
+ if ((crf_wanted & CLF_RENAME) && !(rec->cr_flags & CLF_RENAME))
+ memset(rnm_mov, 0, sizeof(struct changelog_ext_rename));
+
+ /* Update the record's flags accordingly */
+ rec->cr_flags = (rec->cr_flags & CLF_FLAGMASK) | crf_wanted;
+}