+ * Switch to another sequence
+ *
+ * When a current sequence has no available IDs left, OSP has to switch to
+ * another new sequence. OSP requests it using the regular FLDB protocol
+ * and stores synchronously before that is used in precreated. This is needed
+ * to basically have the sequences referenced (not orphaned), otherwise it's
+ * possible that OST has some objects precreated and the clients have data
+ * written to it, but after MDT failover nobody refers those objects and OSP
+ * has no idea that the sequence need cleanup to be done.
+ * While this is very expensive operation, it's supposed to happen very very
+ * infrequently because sequence has 2^32 or 2^48 objects (depending on type)
+ *
+ * \param[in] env LU environment provided by the caller
+ * \param[in] osp OSP device
+ *
+ * \retval 0 on success
+ * \retval negative negated errno on error
+ */
+static int osp_precreate_rollover_new_seq(struct lu_env *env,
+ struct osp_device *osp)
+{
+ struct lu_fid *fid = &osp_env_info(env)->osi_fid;
+ struct lu_fid *last_fid = &osp->opd_last_used_fid;
+ int rc;
+ ENTRY;
+
+ rc = seq_client_get_seq(env, osp->opd_obd->u.cli.cl_seq, &fid->f_seq);
+ if (rc != 0) {
+ CERROR("%s: alloc fid error: rc = %d\n",
+ osp->opd_obd->obd_name, rc);
+ RETURN(rc);
+ }
+
+ fid->f_oid = 1;
+ fid->f_ver = 0;
+ LASSERTF(fid_seq(fid) != fid_seq(last_fid),
+ "fid "DFID", last_fid "DFID"\n", PFID(fid),
+ PFID(last_fid));
+
+ rc = osp_write_last_oid_seq_files(env, osp, fid, 1);
+ if (rc != 0) {
+ CERROR("%s: Can not update oid/seq file: rc = %d\n",
+ osp->opd_obd->obd_name, rc);
+ RETURN(rc);
+ }
+
+ LCONSOLE_INFO("%s: update sequence from "LPX64" to "LPX64"\n",
+ osp->opd_obd->obd_name, fid_seq(last_fid),
+ fid_seq(fid));
+ /* Update last_xxx to the new seq */
+ spin_lock(&osp->opd_pre_lock);
+ osp->opd_last_used_fid = *fid;
+ osp->opd_gap_start_fid = *fid;
+ osp->opd_pre_used_fid = *fid;
+ osp->opd_pre_last_created_fid = *fid;
+ spin_unlock(&osp->opd_pre_lock);
+
+ RETURN(rc);
+}
+
+/**
+ * Find IDs available in current sequence
+ *
+ * The function calculates the highest possible ID and the number of IDs
+ * available in the current sequence OSP is using. The number is limited
+ * artifically by the caller (grow param) and the number of IDs available
+ * in the sequence by nature. The function doesn't require an external
+ * locking.
+ *
+ * \param[in] env LU environment provided by the caller
+ * \param[in] osp OSP device
+ * \param[in] fid FID the caller wants to start with
+ * \param[in] grow how many the caller wants
+ * \param[out] fid the highest calculated FID
+ * \param[out] grow the number of available IDs calculated
+ *
+ * \retval 0 on success, 1 - the sequence is empty
+ */