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LU-12025 osp: allow OS_STATE_* flags from OSTs
[fs/lustre-release.git] / lustre / osp / osp_precreate.c
index 5df08e9..a9ab53c 100644 (file)
  *
  * You should have received a copy of the GNU General Public License
  * version 2 along with this program; If not, see
- * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
+ * http://www.gnu.org/licenses/gpl-2.0.html
  *
  * GPL HEADER END
  */
  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2011, 2012, Intel, Inc.
+ * Copyright (c) 2012, 2017, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
  * Lustre is a trademark of Sun Microsystems, Inc.
  *
- * lustre/osp/osp_sync.c
+ * lustre/osp/osp_precreate.c
  *
  * Lustre OST Proxy Device
  *
  * Author: Alex Zhuravlev <alexey.zhuravlev@intel.com>
  * Author: Mikhail Pershin <mike.pershin@intel.com>
+ * Author: Di Wang <di.wang@intel.com>
  */
 
-#ifndef EXPORT_SYMTAB
-# define EXPORT_SYMTAB
-#endif
 #define DEBUG_SUBSYSTEM S_MDS
 
+#include <linux/kthread.h>
+
+#include <lustre_obdo.h>
+
 #include "osp_internal.h"
 
 /*
  * = import is disconnected =
  *
  * = import is inactive =
- *   in this case osp_declare_object_create() returns an error
+ *   in this case osp_declare_create() returns an error
  *
  */
 
-/*
- * statfs
+/**
+ * Check whether statfs data is expired
+ *
+ * OSP device caches statfs data for the target, the function checks
+ * whether the data is expired or not.
+ *
+ * \param[in] d                OSP device
+ *
+ * \retval             0 - not expired, 1 - expired
  */
 static inline int osp_statfs_need_update(struct osp_device *d)
 {
-       return !cfs_time_before(cfs_time_current(),
-                               d->opd_statfs_fresh_till);
+       return !ktime_before(ktime_get(), d->opd_statfs_fresh_till);
+}
+
+/*
+ * OSP tries to maintain pool of available objects so that calls to create
+ * objects don't block most of time
+ *
+ * each time OSP gets connected to OST, we should start from precreation cleanup
+ */
+static inline bool osp_precreate_running(struct osp_device *d)
+{
+       return !!(d->opd_pre_thread.t_flags & SVC_RUNNING);
+}
+
+static inline bool osp_precreate_stopped(struct osp_device *d)
+{
+       return !!(d->opd_pre_thread.t_flags & SVC_STOPPED);
 }
 
-static void osp_statfs_timer_cb(unsigned long _d)
+static void osp_statfs_timer_cb(cfs_timer_cb_arg_t data)
 {
-       struct osp_device *d = (struct osp_device *) _d;
+       struct osp_device *d = cfs_from_timer(d, data, opd_statfs_timer);
 
        LASSERT(d);
-       cfs_waitq_signal(&d->opd_pre_waitq);
+       if (osp_precreate_running(d))
+               wake_up(&d->opd_pre_waitq);
 }
 
+static void osp_pre_update_msfs(struct osp_device *d, struct obd_statfs *msfs);
+
+/*
+ * The function updates current precreation status if broken, and
+ * updates that cached statfs state if functional, then wakes up waiters.
+ * We don't clear opd_pre_status directly here, but rather leave this
+ * to osp_pre_update_msfs() to do if everything is OK so that we don't
+ * have a race to clear opd_pre_status and then set it to -ENOSPC again.
+ *
+ * \param[in] d                OSP device
+ * \param[in] msfs     statfs data
+ * \param[in] rc       new precreate status for device \a d
+ */
+static void osp_pre_update_status_msfs(struct osp_device *d,
+                                      struct obd_statfs *msfs, int rc)
+{
+       if (rc)
+               d->opd_pre_status = rc;
+       else
+               osp_pre_update_msfs(d, msfs);
+
+       wake_up(&d->opd_pre_user_waitq);
+}
+
+/* Pass in the old statfs data in case the limits have changed */
+void osp_pre_update_status(struct osp_device *d, int rc)
+{
+       osp_pre_update_status_msfs(d, &d->opd_statfs, rc);
+}
+
+
+/**
+ * RPC interpret callback for OST_STATFS RPC
+ *
+ * An interpretation callback called by ptlrpc for OST_STATFS RPC when it is
+ * replied by the target. It's used to maintain statfs cache for the target.
+ * The function fills data from the reply if successful and schedules another
+ * update.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] req      RPC replied
+ * \param[in] aa       callback data
+ * \param[in] rc       RPC result
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
+ */
 static int osp_statfs_interpret(const struct lu_env *env,
-                               struct ptlrpc_request *req,
-                               union ptlrpc_async_args *aa, int rc)
+                               struct ptlrpc_request *req, void *args, int rc)
 {
-       struct obd_import       *imp = req->rq_import;
-       struct obd_statfs       *msfs;
-       struct osp_device       *d;
+       union ptlrpc_async_args *aa = args;
+       struct obd_import *imp = req->rq_import;
+       struct obd_statfs *msfs;
+       struct osp_device *d;
+       u64 maxage_ns;
 
        ENTRY;
 
-       aa = ptlrpc_req_async_args(req);
+       aa = ptlrpc_req_async_args(aa, req);
        d = aa->pointer_arg[0];
        LASSERT(d);
 
@@ -96,33 +165,51 @@ static int osp_statfs_interpret(const struct lu_env *env,
        if (msfs == NULL)
                GOTO(out, rc = -EPROTO);
 
-       d->opd_statfs = *msfs;
-
-       osp_pre_update_status(d, rc);
+       if (d->opd_pre)
+               osp_pre_update_status_msfs(d, msfs, 0);
+       else
+               d->opd_statfs = *msfs;
 
        /* schedule next update */
-       d->opd_statfs_fresh_till = cfs_time_shift(d->opd_statfs_maxage);
-       cfs_timer_arm(&d->opd_statfs_timer, d->opd_statfs_fresh_till);
+       maxage_ns = d->opd_statfs_maxage * NSEC_PER_SEC;
+       d->opd_statfs_fresh_till = ktime_add_ns(ktime_get(), maxage_ns);
+       mod_timer(&d->opd_statfs_timer,
+                 jiffies + cfs_time_seconds(d->opd_statfs_maxage));
        d->opd_statfs_update_in_progress = 0;
 
        CDEBUG(D_CACHE, "updated statfs %p\n", d);
 
        RETURN(0);
 out:
-       /* couldn't update statfs, try again as soon as possible */
-       cfs_waitq_signal(&d->opd_pre_waitq);
+       /* couldn't update statfs, try again with a small delay */
+       d->opd_statfs_fresh_till = ktime_add_ns(ktime_get(), 10 * NSEC_PER_SEC);
+       d->opd_statfs_update_in_progress = 0;
+       if (d->opd_pre != NULL && osp_precreate_running(d))
+               wake_up(&d->opd_pre_waitq);
+
        if (req->rq_import_generation == imp->imp_generation)
-               CERROR("%s: couldn't update statfs: rc = %d\n",
+               CDEBUG(D_CACHE, "%s: couldn't update statfs: rc = %d\n",
                       d->opd_obd->obd_name, rc);
        RETURN(rc);
 }
 
-static int osp_statfs_update(struct osp_device *d)
+/**
+ * Send OST_STATFS RPC
+ *
+ * Sends OST_STATFS RPC to refresh cached statfs data for the target.
+ * Also disables scheduled updates as times OSP may need to refresh
+ * statfs data before expiration. The function doesn't block, instead
+ * an interpretation callback osp_statfs_interpret() is used.
+ *
+ * \param[in] d                OSP device
+ */
+static int osp_statfs_update(const struct lu_env *env, struct osp_device *d)
 {
+       u64 expire = obd_timeout * 1000 * NSEC_PER_SEC;
        struct ptlrpc_request   *req;
        struct obd_import       *imp;
        union ptlrpc_async_args *aa;
-       int                      rc;
+       int rc;
 
        ENTRY;
 
@@ -131,40 +218,74 @@ static int osp_statfs_update(struct osp_device *d)
        imp = d->opd_obd->u.cli.cl_import;
        LASSERT(imp);
 
-       req = ptlrpc_request_alloc(imp, &RQF_OST_STATFS);
+       req = ptlrpc_request_alloc(imp,
+                          d->opd_pre ? &RQF_OST_STATFS : &RQF_MDS_STATFS);
        if (req == NULL)
                RETURN(-ENOMEM);
 
-       rc = ptlrpc_request_pack(req, LUSTRE_OST_VERSION, OST_STATFS);
+       rc = ptlrpc_request_pack(req,
+                        d->opd_pre ? LUSTRE_OST_VERSION : LUSTRE_MDS_VERSION,
+                        d->opd_pre ? OST_STATFS : MDS_STATFS);
        if (rc) {
                ptlrpc_request_free(req);
                RETURN(rc);
        }
        ptlrpc_request_set_replen(req);
-       req->rq_request_portal = OST_CREATE_PORTAL;
+       if (d->opd_pre)
+               req->rq_request_portal = OST_CREATE_PORTAL;
        ptlrpc_at_set_req_timeout(req);
 
-       req->rq_interpret_reply = (ptlrpc_interpterer_t)osp_statfs_interpret;
-       aa = ptlrpc_req_async_args(req);
+       req->rq_interpret_reply = osp_statfs_interpret;
+       aa = ptlrpc_req_async_args(aa, req);
        aa->pointer_arg[0] = d;
 
        /*
         * no updates till reply
         */
-       cfs_timer_disarm(&d->opd_statfs_timer);
-       d->opd_statfs_fresh_till = cfs_time_shift(obd_timeout * 1000);
+       del_timer(&d->opd_statfs_timer);
+       d->opd_statfs_fresh_till = ktime_add_ns(ktime_get(), expire);
        d->opd_statfs_update_in_progress = 1;
 
-       ptlrpcd_add_req(req, PDL_POLICY_ROUND, -1);
+       ptlrpcd_add_req(req);
+
+       /* we still want to sync changes if no new changes are coming */
+       if (ktime_before(ktime_get(), d->opd_sync_next_commit_cb))
+               GOTO(out, rc);
+
+       if (atomic_read(&d->opd_sync_changes)) {
+               struct thandle *th;
+
+               th = dt_trans_create(env, d->opd_storage);
+               if (IS_ERR(th)) {
+                       CERROR("%s: can't sync\n", d->opd_obd->obd_name);
+                       GOTO(out, rc);
+               }
+               rc = dt_trans_start_local(env, d->opd_storage, th);
+               if (rc == 0) {
+                       CDEBUG(D_OTHER, "%s: sync forced, %d changes\n",
+                              d->opd_obd->obd_name,
+                              atomic_read(&d->opd_sync_changes));
+                       osp_sync_add_commit_cb_1s(env, d, th);
+                       dt_trans_stop(env, d->opd_storage, th);
+               }
+       }
 
+out:
        RETURN(0);
 }
 
-/*
- * XXX: there might be a case where removed object(s) do not add free
- * space (empty object). if the number of such deletions is high, then
- * we can start to update statfs too often - a rpc storm
- * TODO: some throttling is needed
+/**
+ * Schedule an immediate update for statfs data
+ *
+ * If cached statfs data claim no free space, but OSP has got a request to
+ * destroy an object (so release some space probably), then we may need to
+ * refresh cached statfs data sooner than planned. The function checks there
+ * is no statfs update going and schedules immediate update if so.
+ * XXX: there might be a case where removed object(s) do not add free space (empty
+ * object). If the number of such deletions is high, then we can start to update
+ * statfs too often causing a RPC storm. some throttling is needed...
+ *
+ * \param[in] d                OSP device where statfs data needs to be refreshed
  */
 void osp_statfs_need_now(struct osp_device *d)
 {
@@ -174,57 +295,326 @@ void osp_statfs_need_now(struct osp_device *d)
                 * then we should poll OST immediately once object destroy
                 * is replied
                 */
-               d->opd_statfs_fresh_till = cfs_time_shift(-1);
-               cfs_timer_disarm(&d->opd_statfs_timer);
-               cfs_waitq_signal(&d->opd_pre_waitq);
+               d->opd_statfs_fresh_till = ktime_sub_ns(ktime_get(), NSEC_PER_SEC);
+               del_timer(&d->opd_statfs_timer);
+               wake_up(&d->opd_pre_waitq);
        }
 }
 
-
-/*
- * OSP tries to maintain pool of available objects so that calls to create
- * objects don't block most of time
+/**
+ * Return number of precreated objects
  *
- * each time OSP gets connected to OST, we should start from precreation cleanup
+ * A simple helper to calculate the number of precreated objects on the device.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] osp      OSP device
+ *
+ * \retval             the number of the precreated objects
  */
-static inline int osp_precreate_running(struct osp_device *d)
-{
-       return !!(d->opd_pre_thread.t_flags & SVC_RUNNING);
-}
-
-static inline int osp_precreate_stopped(struct osp_device *d)
+static inline int osp_objs_precreated(const struct lu_env *env,
+                                     struct osp_device *osp)
 {
-       return !!(d->opd_pre_thread.t_flags & SVC_STOPPED);
+       return osp_fid_diff(&osp->opd_pre_last_created_fid,
+                           &osp->opd_pre_used_fid);
 }
 
-static inline int osp_precreate_near_empty_nolock(struct osp_device *d)
+/**
+ * Check pool of precreated objects is nearly empty
+ *
+ * We should not wait till the pool of the precreated objects is exhausted,
+ * because then there will be a long period of OSP being unavailable for the
+ * new creations due to lenghty precreate RPC. Instead we ask for another
+ * precreation ahead and hopefully have it ready before the current pool is
+ * empty. Notice this function relies on an external locking.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] d                OSP device
+ *
+ * \retval             0 - current pool is good enough, 1 - time to precreate
+ */
+static inline int osp_precreate_near_empty_nolock(const struct lu_env *env,
+                                                 struct osp_device *d)
 {
-       int window = d->opd_pre_last_created - d->opd_pre_used_id;
+       int window = osp_objs_precreated(env, d);
 
        /* don't consider new precreation till OST is healty and
         * has free space */
-       return ((window - d->opd_pre_reserved < d->opd_pre_grow_count / 2) &&
+       return ((window - d->opd_pre_reserved < d->opd_pre_create_count / 2) &&
                (d->opd_pre_status == 0));
 }
 
-static inline int osp_precreate_near_empty(struct osp_device *d)
+/**
+ * Check pool of precreated objects
+ *
+ * This is protected version of osp_precreate_near_empty_nolock(), check that
+ * for the details.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] d                OSP device
+ *
+ * \retval             0 - current pool is good enough, 1 - time to precreate
+ */
+static inline int osp_precreate_near_empty(const struct lu_env *env,
+                                          struct osp_device *d)
 {
        int rc;
 
+       if (d->opd_pre == NULL)
+               return 0;
+
        /* XXX: do we really need locking here? */
-       cfs_spin_lock(&d->opd_pre_lock);
-       rc = osp_precreate_near_empty_nolock(d);
-       cfs_spin_unlock(&d->opd_pre_lock);
+       spin_lock(&d->opd_pre_lock);
+       rc = osp_precreate_near_empty_nolock(env, d);
+       spin_unlock(&d->opd_pre_lock);
        return rc;
 }
 
-static int osp_precreate_send(struct osp_device *d)
+/**
+ * Check given sequence is empty
+ *
+ * Returns a binary result whether the given sequence has some IDs left
+ * or not. Find the details in osp_fid_end_seq(). This is a lock protected
+ * version of that function.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] osp      OSP device
+ *
+ * \retval             0 - current sequence has no IDs, 1 - otherwise
+ */
+static inline int osp_create_end_seq(const struct lu_env *env,
+                                    struct osp_device *osp)
 {
+       struct lu_fid *fid = &osp->opd_pre_used_fid;
+       int rc;
+
+       spin_lock(&osp->opd_pre_lock);
+       rc = osp_fid_end_seq(env, fid);
+       spin_unlock(&osp->opd_pre_lock);
+       return rc;
+}
+
+/**
+ * Write FID into into last_oid/last_seq file
+ *
+ * The function stores the sequence and the in-sequence id into two dedicated
+ * files. The sync argument can be used to request synchronous commit, so the
+ * function won't return until the updates are committed.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] osp      OSP device
+ * \param[in] fid      fid where sequence/id is taken
+ * \param[in] sync     update mode: 0 - asynchronously, 1 - synchronously
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
+ **/
+int osp_write_last_oid_seq_files(struct lu_env *env, struct osp_device *osp,
+                                struct lu_fid *fid, int sync)
+{
+       struct osp_thread_info  *oti = osp_env_info(env);
+       struct lu_buf      *lb_oid = &oti->osi_lb;
+       struct lu_buf      *lb_oseq = &oti->osi_lb2;
+       loff_t             oid_off;
+       u64                oid;
+       loff_t             oseq_off;
+       struct thandle    *th;
+       int                   rc;
+       ENTRY;
+
+       if (osp->opd_storage->dd_rdonly)
+               RETURN(0);
+
+       /* Note: through f_oid is only 32 bits, it will also write 64 bits
+        * for oid to keep compatibility with the previous version. */
+       oid = fid->f_oid;
+       osp_objid_buf_prep(lb_oid, &oid_off,
+                          &oid, osp->opd_index);
+
+       osp_objseq_buf_prep(lb_oseq, &oseq_off,
+                           &fid->f_seq, osp->opd_index);
+
+       th = dt_trans_create(env, osp->opd_storage);
+       if (IS_ERR(th))
+               RETURN(PTR_ERR(th));
+
+       th->th_sync |= sync;
+       rc = dt_declare_record_write(env, osp->opd_last_used_oid_file,
+                                    lb_oid, oid_off, th);
+       if (rc != 0)
+               GOTO(out, rc);
+
+       rc = dt_declare_record_write(env, osp->opd_last_used_seq_file,
+                                    lb_oseq, oseq_off, th);
+       if (rc != 0)
+               GOTO(out, rc);
+
+       rc = dt_trans_start_local(env, osp->opd_storage, th);
+       if (rc != 0)
+               GOTO(out, rc);
+
+       rc = dt_record_write(env, osp->opd_last_used_oid_file, lb_oid,
+                            &oid_off, th);
+       if (rc != 0) {
+               CERROR("%s: can not write to last seq file: rc = %d\n",
+                       osp->opd_obd->obd_name, rc);
+               GOTO(out, rc);
+       }
+       rc = dt_record_write(env, osp->opd_last_used_seq_file, lb_oseq,
+                            &oseq_off, th);
+       if (rc) {
+               CERROR("%s: can not write to last seq file: rc = %d\n",
+                       osp->opd_obd->obd_name, rc);
+               GOTO(out, rc);
+       }
+out:
+       dt_trans_stop(env, osp->opd_storage, th);
+       RETURN(rc);
+}
+
+/**
+ * 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 %#llx to %#llx\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_fid_to_obdid(fid, &osp->opd_last_id);
+       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
+ */
+static int osp_precreate_fids(const struct lu_env *env, struct osp_device *osp,
+                             struct lu_fid *fid, int *grow)
+{
+       struct osp_thread_info  *osi = osp_env_info(env);
+       __u64                   end;
+       int                     i = 0;
+
+       if (fid_is_idif(fid)) {
+               struct lu_fid   *last_fid;
+               struct ost_id   *oi = &osi->osi_oi;
+               int rc;
+
+               spin_lock(&osp->opd_pre_lock);
+               last_fid = &osp->opd_pre_last_created_fid;
+               fid_to_ostid(last_fid, oi);
+               end = min(ostid_id(oi) + *grow, IDIF_MAX_OID);
+               *grow = end - ostid_id(oi);
+               rc = ostid_set_id(oi, ostid_id(oi) + *grow);
+               spin_unlock(&osp->opd_pre_lock);
+
+               if (*grow == 0 || rc)
+                       return 1;
+
+               ostid_to_fid(fid, oi, osp->opd_index);
+               return 0;
+       }
+
+       spin_lock(&osp->opd_pre_lock);
+       *fid = osp->opd_pre_last_created_fid;
+       end = fid->f_oid;
+       end = min((end + *grow), (__u64)LUSTRE_DATA_SEQ_MAX_WIDTH);
+       *grow = end - fid->f_oid;
+       fid->f_oid += end - fid->f_oid;
+       spin_unlock(&osp->opd_pre_lock);
+
+       CDEBUG(D_INFO, "Expect %d, actual %d ["DFID" -- "DFID"]\n",
+              *grow, i, PFID(fid), PFID(&osp->opd_pre_last_created_fid));
+
+       return *grow > 0 ? 0 : 1;
+}
+
+/**
+ * Prepare and send precreate RPC
+ *
+ * The function finds how many objects should be precreated.  Then allocates,
+ * prepares and schedules precreate RPC synchronously. Upon reply the function
+ * wakes up the threads waiting for the new objects on this target. If the
+ * target wasn't able to create all the objects requested, then the next
+ * precreate will be asking for fewer objects (i.e. slow precreate down).
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] d                OSP device
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
+ **/
+static int osp_precreate_send(const struct lu_env *env, struct osp_device *d)
+{
+       struct osp_thread_info  *oti = osp_env_info(env);
        struct ptlrpc_request   *req;
        struct obd_import       *imp;
        struct ost_body         *body;
        int                      rc, grow, diff;
-
+       struct lu_fid           *fid = &oti->osi_fid;
        ENTRY;
 
        /* don't precreate new objects till OST healthy and has free space */
@@ -254,24 +644,40 @@ static int osp_precreate_send(struct osp_device *d)
                RETURN(rc);
        }
 
-       cfs_spin_lock(&d->opd_pre_lock);
-       if (d->opd_pre_grow_count > d->opd_pre_max_grow_count / 2)
-               d->opd_pre_grow_count = d->opd_pre_max_grow_count / 2;
-       grow = d->opd_pre_grow_count;
-       cfs_spin_unlock(&d->opd_pre_lock);
+       spin_lock(&d->opd_pre_lock);
+       if (d->opd_pre_create_count > d->opd_pre_max_create_count / 2)
+               d->opd_pre_create_count = d->opd_pre_max_create_count / 2;
+       grow = d->opd_pre_create_count;
+       spin_unlock(&d->opd_pre_lock);
 
        body = req_capsule_client_get(&req->rq_pill, &RMF_OST_BODY);
        LASSERT(body);
-       body->oa.o_id = d->opd_pre_last_created + grow;
-       body->oa.o_seq = FID_SEQ_OST_MDT0; /* XXX: support for CMD? */
+
+       *fid = d->opd_pre_last_created_fid;
+       rc = osp_precreate_fids(env, d, fid, &grow);
+       if (rc == 1)
+               /* Current seq has been used up*/
+               GOTO(out_req, rc = -ENOSPC);
+
+       if (!osp_is_fid_client(d)) {
+               /* Non-FID client will always send seq 0 because of
+                * compatiblity */
+               LASSERTF(fid_is_idif(fid), "Invalid fid "DFID"\n", PFID(fid));
+               fid->f_seq = 0;
+       }
+
+       fid_to_ostid(fid, &body->oa.o_oi);
        body->oa.o_valid = OBD_MD_FLGROUP;
 
        ptlrpc_request_set_replen(req);
 
+       if (OBD_FAIL_CHECK(OBD_FAIL_OSP_FAKE_PRECREATE))
+               GOTO(ready, rc = 0);
+
        rc = ptlrpc_queue_wait(req);
        if (rc) {
-               CERROR("%s: can't precreate: rc = %d\n",
-                      d->opd_obd->obd_name, rc);
+               CERROR("%s: can't precreate: rc = %d\n", d->opd_obd->obd_name,
+                      rc);
                GOTO(out_req, rc);
        }
        LASSERT(req->rq_transno == 0);
@@ -280,109 +686,200 @@ static int osp_precreate_send(struct osp_device *d)
        if (body == NULL)
                GOTO(out_req, rc = -EPROTO);
 
-       CDEBUG(D_HA, "new last_created %lu\n", (unsigned long) body->oa.o_id);
-       LASSERT(body->oa.o_id > d->opd_pre_used_id);
+       ostid_to_fid(fid, &body->oa.o_oi, d->opd_index);
+
+ready:
+       if (osp_fid_diff(fid, &d->opd_pre_used_fid) <= 0) {
+               CERROR("%s: precreate fid "DFID" <= local used fid "DFID
+                      ": rc = %d\n", d->opd_obd->obd_name,
+                      PFID(fid), PFID(&d->opd_pre_used_fid), -ESTALE);
+               GOTO(out_req, rc = -ESTALE);
+       }
 
-       diff = body->oa.o_id - d->opd_pre_last_created;
+       diff = osp_fid_diff(fid, &d->opd_pre_last_created_fid);
 
-       cfs_spin_lock(&d->opd_pre_lock);
+       spin_lock(&d->opd_pre_lock);
        if (diff < grow) {
                /* the OST has not managed to create all the
                 * objects we asked for */
-               d->opd_pre_grow_count = max(diff, OST_MIN_PRECREATE);
-               d->opd_pre_grow_slow = 1;
+               d->opd_pre_create_count = max(diff, OST_MIN_PRECREATE);
+               d->opd_pre_create_slow = 1;
        } else {
                /* the OST is able to keep up with the work,
-                * we could consider increasing grow_count
+                * we could consider increasing create_count
                 * next time if needed */
-               d->opd_pre_grow_slow = 0;
+               d->opd_pre_create_slow = 0;
        }
-       d->opd_pre_last_created = body->oa.o_id;
-       cfs_spin_unlock(&d->opd_pre_lock);
-       CDEBUG(D_OTHER, "current precreated pool: %llu-%llu\n",
-              d->opd_pre_used_id, d->opd_pre_last_created);
 
+       body = req_capsule_client_get(&req->rq_pill, &RMF_OST_BODY);
+       fid_to_ostid(fid, &body->oa.o_oi);
+
+       d->opd_pre_last_created_fid = *fid;
+       spin_unlock(&d->opd_pre_lock);
+
+       CDEBUG(D_HA, "%s: current precreated pool: "DFID"-"DFID"\n",
+              d->opd_obd->obd_name, PFID(&d->opd_pre_used_fid),
+              PFID(&d->opd_pre_last_created_fid));
 out_req:
        /* now we can wakeup all users awaiting for objects */
        osp_pre_update_status(d, rc);
-       cfs_waitq_signal(&d->opd_pre_user_waitq);
+       wake_up(&d->opd_pre_user_waitq);
 
        ptlrpc_req_finished(req);
        RETURN(rc);
 }
 
-
-static int osp_get_lastid_from_ost(struct osp_device *d)
+/**
+ * Get last precreated object from target (OST)
+ *
+ * Sends synchronous RPC to the target (OST) to learn the last precreated
+ * object. This later is used to remove all unused objects (cleanup orphan
+ * procedure). Also, the next object after one we got will be used as a
+ * starting point for the new precreates.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] d                OSP device
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
+ **/
+static int osp_get_lastfid_from_ost(const struct lu_env *env,
+                                   struct osp_device *d)
 {
-       struct ptlrpc_request   *req;
+       struct ptlrpc_request   *req = NULL;
        struct obd_import       *imp;
-       obd_id                  *reply;
+       struct lu_fid           *last_fid;
        char                    *tmp;
-       int                      rc;
+       int                     rc;
+       ENTRY;
 
        imp = d->opd_obd->u.cli.cl_import;
        LASSERT(imp);
 
-       req = ptlrpc_request_alloc(imp, &RQF_OST_GET_INFO_LAST_ID);
+       req = ptlrpc_request_alloc(imp, &RQF_OST_GET_INFO_LAST_FID);
        if (req == NULL)
                RETURN(-ENOMEM);
 
-       req_capsule_set_size(&req->rq_pill, &RMF_SETINFO_KEY,
-                            RCL_CLIENT, sizeof(KEY_LAST_ID));
+       req_capsule_set_size(&req->rq_pill, &RMF_GETINFO_KEY, RCL_CLIENT,
+                            sizeof(KEY_LAST_FID));
+
        rc = ptlrpc_request_pack(req, LUSTRE_OST_VERSION, OST_GET_INFO);
        if (rc) {
                ptlrpc_request_free(req);
                RETURN(rc);
        }
 
-       tmp = req_capsule_client_get(&req->rq_pill, &RMF_SETINFO_KEY);
-       memcpy(tmp, KEY_LAST_ID, sizeof(KEY_LAST_ID));
+       tmp = req_capsule_client_get(&req->rq_pill, &RMF_GETINFO_KEY);
+       memcpy(tmp, KEY_LAST_FID, sizeof(KEY_LAST_FID));
 
        req->rq_no_delay = req->rq_no_resend = 1;
+       last_fid = req_capsule_client_get(&req->rq_pill, &RMF_FID);
+       fid_cpu_to_le(last_fid, &d->opd_last_used_fid);
+
        ptlrpc_request_set_replen(req);
+
        rc = ptlrpc_queue_wait(req);
        if (rc) {
                /* bad-bad OST.. let sysadm sort this out */
+               if (rc == -ENOTSUPP) {
+                       CERROR("%s: server does not support FID: rc = %d\n",
+                              d->opd_obd->obd_name, -ENOTSUPP);
+               }
                ptlrpc_set_import_active(imp, 0);
                GOTO(out, rc);
        }
 
-       reply = req_capsule_server_get(&req->rq_pill, &RMF_OBD_ID);
-       if (reply == NULL)
+       last_fid = req_capsule_server_get(&req->rq_pill, &RMF_FID);
+       if (last_fid == NULL) {
+               CERROR("%s: Got last_fid failed.\n", d->opd_obd->obd_name);
+               GOTO(out, rc = -EPROTO);
+       }
+
+       if (!fid_is_sane(last_fid)) {
+               CERROR("%s: Got insane last_fid "DFID"\n",
+                      d->opd_obd->obd_name, PFID(last_fid));
                GOTO(out, rc = -EPROTO);
+       }
 
-       d->opd_last_used_id = *reply;
-       CDEBUG(D_HA, "%s: got last_id "LPU64" from OST\n",
-              d->opd_obd->obd_name, d->opd_last_used_id);
+       /* Only update the last used fid, if the OST has objects for
+        * this sequence, i.e. fid_oid > 0 */
+       if (fid_oid(last_fid) > 0)
+               d->opd_last_used_fid = *last_fid;
+
+       CDEBUG(D_HA, "%s: Got last_fid "DFID"\n", d->opd_obd->obd_name,
+              PFID(last_fid));
 
 out:
        ptlrpc_req_finished(req);
        RETURN(rc);
-
 }
 
 /**
- * asks OST to clean precreate orphans
- * and gets next id for new objects
+ * Cleanup orphans on OST
+ *
+ * This function is called in a contex of a dedicated thread handling
+ * all the precreation suff. The function waits till local recovery
+ * is complete, then identify all the unreferenced objects (orphans)
+ * using the highest ID referenced by a local and the highest object
+ * precreated by the target. The found range is a subject to removal
+ * using specially flagged RPC. During this process OSP is marked
+ * unavailable for new objects.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] d                OSP device
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
  */
-static int osp_precreate_cleanup_orphans(struct osp_device *d)
+static int osp_precreate_cleanup_orphans(struct lu_env *env,
+                                        struct osp_device *d)
 {
+       struct osp_thread_info  *osi = osp_env_info(env);
+       struct lu_fid           *last_fid = &osi->osi_fid;
        struct ptlrpc_request   *req = NULL;
        struct obd_import       *imp;
        struct ost_body         *body;
+       struct l_wait_info       lwi = { 0 };
+       int                      update_status = 0;
        int                      rc;
+       int                      diff;
 
        ENTRY;
 
-       LASSERT(d->opd_recovery_completed);
-       LASSERT(d->opd_pre_reserved == 0);
-
-       CDEBUG(D_HA, "%s: going to cleanup orphans since "LPU64"\n",
-               d->opd_obd->obd_name, d->opd_last_used_id);
-
-       if (d->opd_last_used_id < 2) {
-               /* lastid looks strange... ask OST */
-               rc = osp_get_lastid_from_ost(d);
+       /*
+        * wait for local recovery to finish, so we can cleanup orphans
+        * orphans are all objects since "last used" (assigned), but
+        * there might be objects reserved and in some cases they won't
+        * be used. we can't cleanup them till we're sure they won't be
+        * used. also can't we allow new reservations because they may
+        * end up getting orphans being cleaned up below. so we block
+        * new reservations and wait till all reserved objects either
+        * user or released.
+        */
+       spin_lock(&d->opd_pre_lock);
+       d->opd_pre_recovering = 1;
+       spin_unlock(&d->opd_pre_lock);
+       /*
+        * The locking above makes sure the opd_pre_reserved check below will
+        * catch all osp_precreate_reserve() calls who find
+        * "!opd_pre_recovering".
+        */
+       l_wait_event(d->opd_pre_waitq,
+                    (!d->opd_pre_reserved && d->opd_recovery_completed) ||
+                    !osp_precreate_running(d) || d->opd_got_disconnected,
+                    &lwi);
+       if (!osp_precreate_running(d) || d->opd_got_disconnected)
+               GOTO(out, rc = -EAGAIN);
+
+       CDEBUG(D_HA, "%s: going to cleanup orphans since "DFID"\n",
+              d->opd_obd->obd_name, PFID(&d->opd_last_used_fid));
+
+       *last_fid = d->opd_last_used_fid;
+       /* The OSP should already get the valid seq now */
+       LASSERT(!fid_is_zero(last_fid));
+       if (fid_oid(&d->opd_last_used_fid) < 2) {
+               /* lastfid looks strange... ask OST */
+               rc = osp_get_lastfid_from_ost(env, d);
                if (rc)
                        GOTO(out, rc);
        }
@@ -397,6 +894,7 @@ static int osp_precreate_cleanup_orphans(struct osp_device *d)
        rc = ptlrpc_request_pack(req, LUSTRE_OST_VERSION, OST_CREATE);
        if (rc) {
                ptlrpc_request_free(req);
+               req = NULL;
                GOTO(out, rc);
        }
 
@@ -406,9 +904,8 @@ static int osp_precreate_cleanup_orphans(struct osp_device *d)
 
        body->oa.o_flags = OBD_FL_DELORPHAN;
        body->oa.o_valid = OBD_MD_FLFLAGS | OBD_MD_FLGROUP;
-       body->oa.o_seq = FID_SEQ_OST_MDT0;
 
-       body->oa.o_id = d->opd_last_used_id;
+       fid_to_ostid(&d->opd_last_used_fid, &body->oa.o_oi);
 
        ptlrpc_request_set_replen(req);
 
@@ -416,8 +913,10 @@ static int osp_precreate_cleanup_orphans(struct osp_device *d)
        req->rq_no_resend = req->rq_no_delay = 1;
 
        rc = ptlrpc_queue_wait(req);
-       if (rc)
+       if (rc) {
+               update_status = 1;
                GOTO(out, rc);
+       }
 
        body = req_capsule_server_get(&req->rq_pill, &RMF_OST_BODY);
        if (body == NULL)
@@ -426,152 +925,365 @@ static int osp_precreate_cleanup_orphans(struct osp_device *d)
        /*
         * OST provides us with id new pool starts from in body->oa.o_id
         */
-       cfs_spin_lock(&d->opd_pre_lock);
-       if (le64_to_cpu(d->opd_last_used_id) > body->oa.o_id) {
-               d->opd_pre_grow_count = OST_MIN_PRECREATE +
-                                       le64_to_cpu(d->opd_last_used_id) -
-                                       body->oa.o_id;
-               d->opd_pre_last_created = le64_to_cpu(d->opd_last_used_id) + 1;
+       ostid_to_fid(last_fid, &body->oa.o_oi, d->opd_index);
+
+       spin_lock(&d->opd_pre_lock);
+       diff = osp_fid_diff(&d->opd_last_used_fid, last_fid);
+       if (diff > 0) {
+               d->opd_pre_create_count = OST_MIN_PRECREATE + diff;
+               d->opd_pre_last_created_fid = d->opd_last_used_fid;
        } else {
-               d->opd_pre_grow_count = OST_MIN_PRECREATE;
-               d->opd_pre_last_created = body->oa.o_id + 1;
+               d->opd_pre_create_count = OST_MIN_PRECREATE;
+               d->opd_pre_last_created_fid = *last_fid;
        }
-       d->opd_pre_used_id = d->opd_pre_last_created - 1;
-       d->opd_pre_grow_slow = 0;
-       cfs_spin_unlock(&d->opd_pre_lock);
-
-       CDEBUG(D_HA, "Got last_id "LPU64" from OST, last_used is "LPU64
-              ", next "LPU64"\n", body->oa.o_id,
-              le64_to_cpu(d->opd_last_used_id), d->opd_pre_used_id);
-
+       /*
+        * This empties the pre-creation pool and effectively blocks any new
+        * reservations.
+        */
+       LASSERT(fid_oid(&d->opd_pre_last_created_fid) <=
+               LUSTRE_DATA_SEQ_MAX_WIDTH);
+       d->opd_pre_used_fid = d->opd_pre_last_created_fid;
+       d->opd_pre_create_slow = 0;
+       spin_unlock(&d->opd_pre_lock);
+
+       CDEBUG(D_HA, "%s: Got last_id "DFID" from OST, last_created "DFID
+              "last_used is "DFID"\n", d->opd_obd->obd_name, PFID(last_fid),
+              PFID(&d->opd_pre_last_created_fid), PFID(&d->opd_last_used_fid));
 out:
        if (req)
                ptlrpc_req_finished(req);
 
+       /*
+        * If rc is zero, the pre-creation window should have been emptied.
+        * Since waking up the herd would be useless without pre-created
+        * objects, we defer the signal to osp_precreate_send() in that case.
+        */
+       if (rc != 0) {
+               if (update_status) {
+                       CERROR("%s: cannot cleanup orphans: rc = %d\n",
+                              d->opd_obd->obd_name, rc);
+                       /* we can't proceed from here, OST seem to
+                        * be in a bad shape, better to wait for
+                        * a new instance of the server and repeat
+                        * from the beginning. notify possible waiters
+                        * this OSP isn't quite functional yet */
+                       osp_pre_update_status(d, rc);
+               } else {
+                       wake_up(&d->opd_pre_user_waitq);
+               }
+       } else {
+               spin_lock(&d->opd_pre_lock);
+               d->opd_pre_recovering = 0;
+               spin_unlock(&d->opd_pre_lock);
+       }
+
        RETURN(rc);
 }
 
-/*
- * the function updates current precreation status used: functional or not
+/**
+ * Update precreate status using statfs data
+ *
+ * The function decides whether this OSP should be used for new objects.
+ * IOW, whether this OST is used up or has some free space. Cached statfs
+ * data is used to make this decision. If the latest result of statfs
+ * request (rc argument) is not success, then just mark OSP unavailable
+ * right away.
  *
- * rc is a last code from the transport, rc == 0 meaning transport works
- * well and users of lod can use objects from this OSP
+ * The new statfs data is passed in \a msfs and needs to be stored into
+ * opd_statfs, but only after the various flags in os_state are set, so
+ * that the new statfs data is not visible without appropriate flags set.
+ * As such, there is no need to clear the flags here, since this is called
+ * with new statfs data, and they should not be cleared if sent from OST.
  *
- * the status depends on current usage of OST
+ * Add a bit of hysteresis so this flag isn't continually flapping, and
+ * ensure that new files don't get extremely fragmented due to only a
+ * small amount of available space in the filesystem.  We want to set
+ * the ENOSPC/ENOINO flags unconditionally when there is less than the
+ * reserved size free, and still copy them from the old state when there
+ * is less than 2*reserved size free space or inodes.
+ *
+ * \param[in] d                OSP device
+ * \param[in] msfs     statfs data
  */
-void osp_pre_update_status(struct osp_device *d, int rc)
+static void osp_pre_update_msfs(struct osp_device *d, struct obd_statfs *msfs)
 {
-       struct obd_statfs       *msfs = &d->opd_statfs;
-       int                      old = d->opd_pre_status;
-       __u64                    used;
-
-       d->opd_pre_status = rc;
-       if (rc)
-               goto out;
-
-       if (likely(msfs->os_type)) {
-               used = min_t(__u64, (msfs->os_blocks - msfs->os_bfree) >> 10,
-                                   1 << 30);
-               if ((msfs->os_ffree < 32) || (msfs->os_bavail < used)) {
-                       d->opd_pre_status = -ENOSPC;
-                       if (old != -ENOSPC)
-                               CDEBUG(D_INFO, "%s: status: "LPU64" blocks, "
-                                      LPU64" free, "LPU64" used, "LPU64" "
-                                      "avail -> %d: rc = %d\n",
-                                      d->opd_obd->obd_name, msfs->os_blocks,
-                                      msfs->os_bfree, used, msfs->os_bavail,
-                                      d->opd_pre_status, rc);
-                       CDEBUG(D_INFO,
-                              "non-commited changes: %lu, in progress: %u\n",
-                              d->opd_syn_changes, d->opd_syn_rpc_in_progress);
-               } else if (old == -ENOSPC) {
-                       d->opd_pre_status = 0;
-                       d->opd_pre_grow_slow = 0;
-                       d->opd_pre_grow_count = OST_MIN_PRECREATE;
-                       cfs_waitq_signal(&d->opd_pre_waitq);
-                       CDEBUG(D_INFO, "%s: no space: "LPU64" blocks, "LPU64
-                              " free, "LPU64" used, "LPU64" avail -> %d: "
-                              "rc = %d\n", d->opd_obd->obd_name,
-                              msfs->os_blocks, msfs->os_bfree, used,
-                              msfs->os_bavail, d->opd_pre_status, rc);
+       u32 old_state = d->opd_statfs.os_state;
+       u32 reserved_ino_low = 32;      /* could be tunable in the future */
+       u32 reserved_ino_high = reserved_ino_low * 2;
+       u64 available_mb;
+
+       /* statfs structure not initialized yet */
+       if (unlikely(!msfs->os_type))
+               return;
+
+       /* if the low and high watermarks have not been initialized yet */
+       if (unlikely(d->opd_reserved_mb_high == 0 &&
+                    d->opd_reserved_mb_low == 0)) {
+               /* Use ~0.1% by default to disable object allocation,
+                * and ~0.2% to enable, size in MB, set both watermark
+                */
+               spin_lock(&d->opd_pre_lock);
+               if (d->opd_reserved_mb_high == 0 &&
+                   d->opd_reserved_mb_low == 0) {
+                       d->opd_reserved_mb_low = ((msfs->os_bsize >> 10) *
+                                                 msfs->os_blocks) >> 20;
+                       if (d->opd_reserved_mb_low == 0)
+                               d->opd_reserved_mb_low = 1;
+                       d->opd_reserved_mb_high =
+                               (d->opd_reserved_mb_low << 1) + 1;
                }
+               spin_unlock(&d->opd_pre_lock);
        }
 
+       available_mb = (msfs->os_bavail * (msfs->os_bsize >> 10)) >> 10;
+       if (msfs->os_ffree < reserved_ino_low)
+               msfs->os_state |= OS_STATE_ENOINO;
+       else if (msfs->os_ffree <= reserved_ino_high)
+               msfs->os_state |= old_state & OS_STATE_ENOINO;
+       /* else don't clear flags in new msfs->os_state sent from OST */
+
+       CDEBUG(D_INFO,
+              "%s: blocks=%llu free=%llu avail=%llu avail_mb=%llu hwm_mb=%u files=%llu ffree=%llu state=%x: rc = %d\n",
+              d->opd_obd->obd_name, msfs->os_blocks, msfs->os_bfree,
+              msfs->os_bavail, available_mb, d->opd_reserved_mb_high,
+              msfs->os_files, msfs->os_ffree, msfs->os_state,
+              d->opd_pre_status);
+       if (available_mb < d->opd_reserved_mb_low)
+               msfs->os_state |= OS_STATE_ENOSPC;
+       else if (available_mb <= d->opd_reserved_mb_high)
+               msfs->os_state |= old_state & OS_STATE_ENOSPC;
+       /* else don't clear flags in new msfs->os_state sent from OST */
+
+       if (msfs->os_state & (OS_STATE_ENOINO | OS_STATE_ENOSPC)) {
+               d->opd_pre_status = -ENOSPC;
+               if (!(old_state & (OS_STATE_ENOINO | OS_STATE_ENOSPC)))
+                       CDEBUG(D_INFO, "%s: full: state=%x: rc = %x\n",
+                              d->opd_obd->obd_name, msfs->os_state,
+                              d->opd_pre_status);
+               CDEBUG(D_INFO, "uncommitted changes=%u in_progress=%u\n",
+                      atomic_read(&d->opd_sync_changes),
+                      atomic_read(&d->opd_sync_rpcs_in_progress));
+       } else if (old_state & (OS_STATE_ENOINO | OS_STATE_ENOSPC)) {
+               d->opd_pre_status = 0;
+               spin_lock(&d->opd_pre_lock);
+               d->opd_pre_create_slow = 0;
+               d->opd_pre_create_count = OST_MIN_PRECREATE;
+               spin_unlock(&d->opd_pre_lock);
+               wake_up(&d->opd_pre_waitq);
+
+               CDEBUG(D_INFO,
+                      "%s: available: state=%x: rc = %d\n",
+                      d->opd_obd->obd_name, msfs->os_state,
+                      d->opd_pre_status);
+       } else {
+               /* we only get here if rc == 0 in the caller */
+               d->opd_pre_status = 0;
+       }
+
+       /* Object precreation skipped on OST if manually disabled */
+       if (d->opd_pre_max_create_count == 0)
+               msfs->os_state |= OS_STATE_NOPRECREATE;
+       /* else don't clear flags in new msfs->os_state sent from OST */
+
+       /* copy only new statfs state to make it visible to MDS threads */
+       if (&d->opd_statfs != msfs)
+               d->opd_statfs = *msfs;
+}
+
+/**
+ * Initialize FID for precreation
+ *
+ * For a just created new target, a new sequence should be taken.
+ * The function checks there is no IDIF in use (if the target was
+ * added with the older version of Lustre), then requests a new
+ * sequence from FLDB using the regular protocol. Then this new
+ * sequence is stored on a persisten storage synchronously to prevent
+ * possible object leakage (for the detail see the description for
+ * osp_precreate_rollover_new_seq()).
+ *
+ * \param[in] osp      OSP device
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
+ */
+int osp_init_pre_fid(struct osp_device *osp)
+{
+       struct lu_env           env;
+       struct osp_thread_info  *osi;
+       struct lu_client_seq    *cli_seq;
+       struct lu_fid           *last_fid;
+       int                     rc;
+       ENTRY;
+
+       LASSERT(osp->opd_pre != NULL);
+
+       /* Let's check if the current last_seq/fid is valid,
+        * otherwise request new sequence from the controller */
+       if (osp_is_fid_client(osp) && osp->opd_group != 0) {
+               /* Non-MDT0 can only use normal sequence for
+                * OST objects */
+               if (fid_is_norm(&osp->opd_last_used_fid))
+                       RETURN(0);
+       } else {
+               /* Initially MDT0 will start with IDIF, after
+                * that it will request new sequence from the
+                * controller */
+               if (fid_is_idif(&osp->opd_last_used_fid) ||
+                   fid_is_norm(&osp->opd_last_used_fid))
+                       RETURN(0);
+       }
+
+       if (!fid_is_zero(&osp->opd_last_used_fid))
+               CWARN("%s: invalid last used fid "DFID
+                     ", try to get new sequence.\n",
+                     osp->opd_obd->obd_name,
+                     PFID(&osp->opd_last_used_fid));
+
+       rc = lu_env_init(&env, osp->opd_dt_dev.dd_lu_dev.ld_type->ldt_ctx_tags);
+       if (rc) {
+               CERROR("%s: init env error: rc = %d\n",
+                      osp->opd_obd->obd_name, rc);
+               RETURN(rc);
+       }
+
+       osi = osp_env_info(&env);
+       last_fid = &osi->osi_fid;
+       fid_zero(last_fid);
+       /* For a freshed fs, it will allocate a new sequence first */
+       if (osp_is_fid_client(osp) && osp->opd_group != 0) {
+               cli_seq = osp->opd_obd->u.cli.cl_seq;
+               rc = seq_client_get_seq(&env, cli_seq, &last_fid->f_seq);
+               if (rc != 0) {
+                       CERROR("%s: alloc fid error: rc = %d\n",
+                              osp->opd_obd->obd_name, rc);
+                       GOTO(out, rc);
+               }
+       } else {
+               last_fid->f_seq = fid_idif_seq(0, osp->opd_index);
+       }
+       last_fid->f_oid = 1;
+       last_fid->f_ver = 0;
+
+       spin_lock(&osp->opd_pre_lock);
+       osp->opd_last_used_fid = *last_fid;
+       osp->opd_pre_used_fid = *last_fid;
+       osp->opd_pre_last_created_fid = *last_fid;
+       spin_unlock(&osp->opd_pre_lock);
+       rc = osp_write_last_oid_seq_files(&env, osp, last_fid, 1);
+       if (rc != 0) {
+               CERROR("%s: write fid error: rc = %d\n",
+                      osp->opd_obd->obd_name, rc);
+               GOTO(out, rc);
+       }
 out:
-       cfs_waitq_signal(&d->opd_pre_user_waitq);
+       lu_env_fini(&env);
+       RETURN(rc);
 }
 
+/**
+ * The core of precreate functionality
+ *
+ * The function implements the main precreation loop. Basically it
+ * involves connecting to the target, precerate FID initialization,
+ * identifying and removing orphans, then serving precreation. As
+ * part of the latter, the thread is responsible for statfs data
+ * updates. The precreation is mostly driven by another threads
+ * asking for new OST objects - those askers wake the thread when
+ * the number of precreated objects reach low watermark.
+ * After a disconnect, the sequence above repeats. This is keep going
+ * until the thread is requested to stop.
+ *
+ * \param[in] _arg     private data the thread (OSP device to handle)
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
+ */
 static int osp_precreate_thread(void *_arg)
 {
        struct osp_device       *d = _arg;
        struct ptlrpc_thread    *thread = &d->opd_pre_thread;
        struct l_wait_info       lwi = { 0 };
-       char                     pname[16];
+       struct l_wait_info       lwi2 = LWI_TIMEOUT(cfs_time_seconds(5),
+                                                   back_to_sleep, NULL);
+       struct lu_env            env;
        int                      rc;
 
        ENTRY;
 
-       sprintf(pname, "osp-pre-%u\n", d->opd_index);
-       cfs_daemonize(pname);
+       rc = lu_env_init(&env, d->opd_dt_dev.dd_lu_dev.ld_type->ldt_ctx_tags);
+       if (rc) {
+               CERROR("%s: init env error: rc = %d\n", d->opd_obd->obd_name,
+                      rc);
+
+               spin_lock(&d->opd_pre_lock);
+               thread->t_flags = SVC_STOPPED;
+               spin_unlock(&d->opd_pre_lock);
+               wake_up(&thread->t_ctl_waitq);
+
+               RETURN(rc);
+       }
 
-       cfs_spin_lock(&d->opd_pre_lock);
+       spin_lock(&d->opd_pre_lock);
        thread->t_flags = SVC_RUNNING;
-       cfs_spin_unlock(&d->opd_pre_lock);
-       cfs_waitq_signal(&thread->t_ctl_waitq);
+       spin_unlock(&d->opd_pre_lock);
+       wake_up(&thread->t_ctl_waitq);
 
        while (osp_precreate_running(d)) {
                /*
                 * need to be connected to OST
                 */
                while (osp_precreate_running(d)) {
+                       if ((d->opd_pre == NULL || d->opd_pre_recovering) &&
+                           d->opd_imp_connected &&
+                           !d->opd_got_disconnected)
+                               break;
                        l_wait_event(d->opd_pre_waitq,
                                     !osp_precreate_running(d) ||
-                                    d->opd_new_connection, &lwi);
-
-                       if (!osp_precreate_running(d))
-                               break;
+                                    d->opd_new_connection,
+                                    &lwi);
 
                        if (!d->opd_new_connection)
                                continue;
 
-                       /* got connected */
                        d->opd_new_connection = 0;
                        d->opd_got_disconnected = 0;
                        break;
                }
 
-               osp_statfs_update(d);
+               if (!osp_precreate_running(d))
+                       break;
 
-               /*
-                * wait for local recovery to finish, so we can cleanup orphans
-                * orphans are all objects since "last used" (assigned), but
-                * there might be objects reserved and in some cases they won't
-                * be used. we can't cleanup them till we're sure they won't be
-                * used. so we block new reservations and wait till all reserved
-                * objects either user or released.
-                */
-               l_wait_event(d->opd_pre_waitq, (!d->opd_pre_reserved &&
-                                               d->opd_recovery_completed) ||
-                            !osp_precreate_running(d) ||
-                            d->opd_got_disconnected, &lwi);
-
-               if (osp_precreate_running(d) && !d->opd_got_disconnected) {
-                       rc = osp_precreate_cleanup_orphans(d);
-                       if (rc) {
-                               CERROR("%s: cannot cleanup orphans: rc = %d\n",
-                                      d->opd_obd->obd_name,  rc);
-                               /* we can't proceed from here, OST seem to
-                                * be in a bad shape, better to wait for
-                                * a new instance of the server and repeat
-                                * from the beginning. notify possible waiters
-                                * this OSP isn't quite functional yet */
-                               osp_pre_update_status(d, rc);
-                               cfs_waitq_signal(&d->opd_pre_user_waitq);
-                               l_wait_event(d->opd_pre_waitq,
-                                            !osp_precreate_running(d) ||
-                                            d->opd_new_connection, &lwi);
+               if (d->opd_pre) {
+                       LASSERT(d->opd_obd->u.cli.cl_seq != NULL);
+                       /* Sigh, fid client is not ready yet */
+                       if (d->opd_obd->u.cli.cl_seq->lcs_exp == NULL)
                                continue;
 
+                       /* Init fid for osp_precreate if necessary */
+                       rc = osp_init_pre_fid(d);
+                       if (rc != 0) {
+                               class_export_put(d->opd_exp);
+                               d->opd_obd->u.cli.cl_seq->lcs_exp = NULL;
+                               CERROR("%s: init pre fid error: rc = %d\n",
+                                               d->opd_obd->obd_name, rc);
+                               continue;
+                       }
+               }
+
+               if (osp_statfs_update(&env, d)) {
+                       l_wait_event(d->opd_pre_waitq,
+                                    !osp_precreate_running(d), &lwi2);
+                       continue;
+               }
+
+               if (d->opd_pre) {
+                       /*
+                        * Clean up orphans or recreate missing objects.
+                        */
+                       rc = osp_precreate_cleanup_orphans(&env, d);
+                       if (rc != 0) {
+                               schedule_timeout_interruptible(cfs_time_seconds(1));
+                               continue;
                        }
                }
 
@@ -581,7 +1293,7 @@ static int osp_precreate_thread(void *_arg)
                while (osp_precreate_running(d)) {
                        l_wait_event(d->opd_pre_waitq,
                                     !osp_precreate_running(d) ||
-                                    osp_precreate_near_empty(d) ||
+                                    osp_precreate_near_empty(&env, d) ||
                                     osp_statfs_need_update(d) ||
                                     d->opd_got_disconnected, &lwi);
 
@@ -594,14 +1306,36 @@ static int osp_precreate_thread(void *_arg)
                                break;
 
                        if (osp_statfs_need_update(d))
-                               osp_statfs_update(d);
+                               if (osp_statfs_update(&env, d))
+                                       break;
+
+                       if (d->opd_pre == NULL)
+                               continue;
+
+                       /* To avoid handling different seq in precreate/orphan
+                        * cleanup, it will hold precreate until current seq is
+                        * used up. */
+                       if (unlikely(osp_precreate_end_seq(&env, d) &&
+                           !osp_create_end_seq(&env, d)))
+                               continue;
+
+                       if (unlikely(osp_precreate_end_seq(&env, d) &&
+                                    osp_create_end_seq(&env, d))) {
+                               LCONSOLE_INFO("%s:%#llx is used up."
+                                             " Update to new seq\n",
+                                             d->opd_obd->obd_name,
+                                        fid_seq(&d->opd_pre_last_created_fid));
+                               rc = osp_precreate_rollover_new_seq(&env, d);
+                               if (rc)
+                                       continue;
+                       }
 
-                       if (osp_precreate_near_empty(d)) {
-                               rc = osp_precreate_send(d);
+                       if (osp_precreate_near_empty(&env, d)) {
+                               rc = osp_precreate_send(&env, d);
                                /* osp_precreate_send() sets opd_pre_status
                                 * in case of error, that prevent the using of
                                 * failed device. */
-                               if (rc != 0 && rc != -ENOSPC &&
+                               if (rc < 0 && rc != -ENOSPC &&
                                    rc != -ETIMEDOUT && rc != -ENOTCONN)
                                        CERROR("%s: cannot precreate objects:"
                                               " rc = %d\n",
@@ -611,25 +1345,55 @@ static int osp_precreate_thread(void *_arg)
        }
 
        thread->t_flags = SVC_STOPPED;
-       cfs_waitq_signal(&thread->t_ctl_waitq);
+       lu_env_fini(&env);
+       wake_up(&thread->t_ctl_waitq);
 
        RETURN(0);
 }
 
-static int osp_precreate_ready_condition(struct osp_device *d)
+/**
+ * Check when to stop to wait for precreate objects.
+ *
+ * The caller wanting a new OST object can't wait undefinitely. The
+ * function checks for few conditions including available new OST
+ * objects, disconnected OST, lack of space with no pending destroys,
+ * etc. IOW, it checks whether the current OSP state is good to keep
+ * waiting or it's better to give up.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] d                OSP device
+ *
+ * \retval             0 - keep waiting, 1 - no luck
+ */
+static int osp_precreate_ready_condition(const struct lu_env *env,
+                                        struct osp_device *d)
 {
-       __u64 next;
+       if (d->opd_pre_recovering)
+               return 0;
 
        /* ready if got enough precreated objects */
        /* we need to wait for others (opd_pre_reserved) and our object (+1) */
-       next = d->opd_pre_used_id + d->opd_pre_reserved + 1;
-       if (next <= d->opd_pre_last_created)
+       if (d->opd_pre_reserved + 1 < osp_objs_precreated(env, d))
+               return 1;
+
+       /* ready if OST reported no space and no destroys in progress */
+       if (atomic_read(&d->opd_sync_changes) +
+           atomic_read(&d->opd_sync_rpcs_in_progress) == 0 &&
+           d->opd_pre_status == -ENOSPC)
                return 1;
 
-       /* ready if OST reported no space and no destoys in progress */
-       if (d->opd_syn_changes + d->opd_syn_rpc_in_progress == 0 &&
-           d->opd_pre_status != 0)
+       /* Bail out I/O fails to OST */
+       if (d->opd_pre_status != 0 &&
+           d->opd_pre_status != -EAGAIN &&
+           d->opd_pre_status != -ENODEV &&
+           d->opd_pre_status != -ENOTCONN &&
+           d->opd_pre_status != -ENOSPC) {
+               /* DEBUG LU-3230 */
+               if (d->opd_pre_status != -EIO)
+                       CERROR("%s: precreate failed opd_pre_status %d\n",
+                              d->opd_obd->obd_name, d->opd_pre_status);
                return 1;
+       }
 
        return 0;
 }
@@ -638,92 +1402,97 @@ static int osp_precreate_timeout_condition(void *data)
 {
        struct osp_device *d = data;
 
-       LCONSOLE_WARN("%s: slow creates, last="LPU64", next="LPU64", "
-                     "reserved="LPU64", syn_changes=%lu, "
-                     "syn_rpc_in_progress=%d, status=%d\n",
-                     d->opd_obd->obd_name, d->opd_pre_last_created,
-                     d->opd_pre_used_id, d->opd_pre_reserved,
-                     d->opd_syn_changes, d->opd_syn_rpc_in_progress,
-                     d->opd_pre_status);
+       CDEBUG(D_HA, "%s: slow creates, last="DFID", next="DFID", "
+             "reserved=%llu, sync_changes=%u, "
+             "sync_rpcs_in_progress=%d, status=%d\n",
+             d->opd_obd->obd_name, PFID(&d->opd_pre_last_created_fid),
+             PFID(&d->opd_pre_used_fid), d->opd_pre_reserved,
+             atomic_read(&d->opd_sync_changes),
+             atomic_read(&d->opd_sync_rpcs_in_progress),
+             d->opd_pre_status);
 
-       return 0;
+       return 1;
 }
 
-/*
- * called to reserve object in the pool
- * return codes:
- *  ENOSPC - no space on corresponded OST
- *  EAGAIN - precreation is in progress, try later
- *  EIO    - no access to OST
+/**
+ * Reserve object in precreate pool
+ *
+ * When the caller wants to create a new object on this target (target
+ * represented by the given OSP), it should declare this intention using
+ * a regular ->dt_declare_create() OSD API method. Then OSP will be trying
+ * to reserve an object in the existing precreated pool or wait up to
+ * obd_timeout for the available object to appear in the pool (a dedicated
+ * thread will be doing real precreation in background). The object can be
+ * consumed later with osp_precreate_get_fid() or be released with call to
+ * lu_object_put(). Notice the function doesn't reserve a specific ID, just
+ * some ID. The actual ID assignment happen in osp_precreate_get_fid().
+ * If the space on the target is short and there is a pending object destroy,
+ * then the function forces local commit to speedup space release (see
+ * osp_sync.c for the details).
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] d                OSP device
+ *
+ * \retval             0 on success
+ * \retval             -ENOSPC when no space on OST
+ * \retval             -EAGAIN try later, slow precreation in progress
+ * \retval             -EIO when no access to OST
  */
 int osp_precreate_reserve(const struct lu_env *env, struct osp_device *d)
 {
-       struct l_wait_info       lwi;
-       cfs_time_t               expire = cfs_time_shift(obd_timeout);
-       int                      precreated, rc;
-       int                      count = 0;
+       time64_t expire = ktime_get_seconds() + obd_timeout;
+       struct l_wait_info lwi;
+       int precreated, rc, synced = 0;
 
        ENTRY;
 
-       LASSERT(d->opd_pre_last_created >= d->opd_pre_used_id);
+       LASSERTF(osp_objs_precreated(env, d) >= 0, "Last created FID "DFID
+                "Next FID "DFID"\n", PFID(&d->opd_pre_last_created_fid),
+                PFID(&d->opd_pre_used_fid));
 
-       lwi = LWI_TIMEOUT(cfs_time_seconds(obd_timeout),
-                         osp_precreate_timeout_condition, d);
+       /* opd_pre_max_create_count 0 to not use specified OST. */
+       if (d->opd_pre_max_create_count == 0)
+               RETURN(-ENOBUFS);
 
        /*
         * wait till:
         *  - preallocation is done
         *  - no free space expected soon
         *  - can't connect to OST for too long (obd_timeout)
+        *  - OST can allocate fid sequence.
         */
        while ((rc = d->opd_pre_status) == 0 || rc == -ENOSPC ||
-               rc == -ENODEV) {
-               if (unlikely(rc == -ENODEV)) {
-                       if (cfs_time_aftereq(cfs_time_current(), expire))
-                               break;
-               }
-
-#if LUSTRE_VERSION_CODE < OBD_OCD_VERSION(2, 3, 90, 0)
-               /*
-                * to address Andreas's concern on possible busy-loop
-                * between this thread and osp_precreate_send()
-                */
-               if (unlikely(count++ == 1000)) {
-                       osp_precreate_timeout_condition(d);
-                       LBUG();
-               }
-#endif
+               rc == -ENODEV || rc == -EAGAIN || rc == -ENOTCONN) {
 
                /*
                 * increase number of precreations
                 */
-               if (d->opd_pre_grow_count < d->opd_pre_max_grow_count &&
-                   d->opd_pre_grow_slow == 0 &&
-                   (d->opd_pre_last_created - d->opd_pre_used_id <=
-                    d->opd_pre_grow_count / 4 + 1)) {
-                       cfs_spin_lock(&d->opd_pre_lock);
-                       d->opd_pre_grow_slow = 1;
-                       d->opd_pre_grow_count *= 2;
-                       cfs_spin_unlock(&d->opd_pre_lock);
+               precreated = osp_objs_precreated(env, d);
+               if (d->opd_pre_create_count < d->opd_pre_max_create_count &&
+                   d->opd_pre_create_slow == 0 &&
+                   precreated <= (d->opd_pre_create_count / 4 + 1)) {
+                       spin_lock(&d->opd_pre_lock);
+                       d->opd_pre_create_slow = 1;
+                       d->opd_pre_create_count *= 2;
+                       spin_unlock(&d->opd_pre_lock);
                }
 
-               /*
-                * we never use the last object in the window
-                */
-               cfs_spin_lock(&d->opd_pre_lock);
-               precreated = d->opd_pre_last_created - d->opd_pre_used_id;
-               if (precreated > d->opd_pre_reserved) {
+               spin_lock(&d->opd_pre_lock);
+               precreated = osp_objs_precreated(env, d);
+               if (precreated > d->opd_pre_reserved &&
+                   !d->opd_pre_recovering) {
                        d->opd_pre_reserved++;
-                       cfs_spin_unlock(&d->opd_pre_lock);
+                       spin_unlock(&d->opd_pre_lock);
                        rc = 0;
 
                        /* XXX: don't wake up if precreation is in progress */
-                       if (osp_precreate_near_empty_nolock(d))
-                               cfs_waitq_signal(&d->opd_pre_waitq);
+                       if (osp_precreate_near_empty_nolock(env, d) &&
+                          !osp_precreate_end_seq_nolock(env, d))
+                               wake_up(&d->opd_pre_waitq);
 
                        break;
                }
-               cfs_spin_unlock(&d->opd_pre_lock);
+               spin_unlock(&d->opd_pre_lock);
 
                /*
                 * all precreated objects have been used and no-space
@@ -732,63 +1501,126 @@ int osp_precreate_reserve(const struct lu_env *env, struct osp_device *d)
                 * wait till that is done - some space might be released
                 */
                if (unlikely(rc == -ENOSPC)) {
-                       if (d->opd_syn_changes) {
+                       if (atomic_read(&d->opd_sync_changes) && synced == 0) {
                                /* force local commit to release space */
                                dt_commit_async(env, d->opd_storage);
+                               osp_sync_check_for_work(d);
+                               synced = 1;
                        }
-                       if (d->opd_syn_rpc_in_progress) {
+                       if (atomic_read(&d->opd_sync_rpcs_in_progress)) {
                                /* just wait till destroys are done */
                                /* see l_wait_even() few lines below */
                        }
-                       if (d->opd_syn_changes +
-                           d->opd_syn_rpc_in_progress == 0) {
+                       if (atomic_read(&d->opd_sync_changes) +
+                           atomic_read(&d->opd_sync_rpcs_in_progress) == 0) {
                                /* no hope for free space */
                                break;
                        }
                }
 
                /* XXX: don't wake up if precreation is in progress */
-               cfs_waitq_signal(&d->opd_pre_waitq);
+               wake_up(&d->opd_pre_waitq);
+
+               lwi = LWI_TIMEOUT(cfs_time_seconds(obd_timeout),
+                                 osp_precreate_timeout_condition, d);
+               if (ktime_get_seconds() >= expire) {
+                       rc = -ETIMEDOUT;
+                       break;
+               }
 
                l_wait_event(d->opd_pre_user_waitq,
-                            osp_precreate_ready_condition(d), &lwi);
+                            osp_precreate_ready_condition(env, d), &lwi);
        }
 
        RETURN(rc);
 }
 
-/*
- * this function relies on reservation made before
+/**
+ * Get a FID from precreation pool
+ *
+ * The function is a companion for osp_precreate_reserve() - it assigns
+ * a specific FID from the precreate. The function should be called only
+ * if the call to osp_precreate_reserve() was successful. The function
+ * updates a local storage to remember the highest object ID referenced
+ * by the node in the given sequence.
+ *
+ * A very importan details: this is supposed to be called once the
+ * transaction is started, so on-disk update will be atomic with the
+ * data (like LOVEA) refering this object. Then the object won't be leaked:
+ * either it's referenced by the committed transaction or it's a subject
+ * to the orphan cleanup procedure.
+ *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] d                OSP device
+ * \param[out] fid     generated FID
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
  */
-__u64 osp_precreate_get_id(struct osp_device *d)
+int osp_precreate_get_fid(const struct lu_env *env, struct osp_device *d,
+                         struct lu_fid *fid)
 {
-       obd_id objid;
-
+       struct lu_fid *pre_used_fid = &d->opd_pre_used_fid;
        /* grab next id from the pool */
-       cfs_spin_lock(&d->opd_pre_lock);
-       LASSERT(d->opd_pre_used_id < d->opd_pre_last_created);
-       objid = ++d->opd_pre_used_id;
+       spin_lock(&d->opd_pre_lock);
+
+       LASSERTF(osp_fid_diff(&d->opd_pre_used_fid,
+                            &d->opd_pre_last_created_fid) < 0,
+                "next fid "DFID" last created fid "DFID"\n",
+                PFID(&d->opd_pre_used_fid),
+                PFID(&d->opd_pre_last_created_fid));
+
+       /*
+        * When sequence is used up, new one should be allocated in
+        * osp_precreate_rollover_new_seq. So ASSERT here to avoid
+        * objid overflow.
+        */
+       LASSERTF(osp_fid_end_seq(env, pre_used_fid) == 0,
+                "next fid "DFID" last created fid "DFID"\n",
+                PFID(&d->opd_pre_used_fid),
+                PFID(&d->opd_pre_last_created_fid));
+       /* Non IDIF fids shoulnd't get here with oid == 0xFFFFFFFF. */
+       if (fid_is_idif(pre_used_fid) &&
+           unlikely(fid_oid(pre_used_fid) == LUSTRE_DATA_SEQ_MAX_WIDTH))
+               pre_used_fid->f_seq++;
+
+       d->opd_pre_used_fid.f_oid++;
+       memcpy(fid, &d->opd_pre_used_fid, sizeof(*fid));
        d->opd_pre_reserved--;
        /*
         * last_used_id must be changed along with getting new id otherwise
         * we might miscalculate gap causing object loss or leak
         */
-       osp_update_last_id(d, objid);
-       cfs_spin_unlock(&d->opd_pre_lock);
+       osp_update_last_fid(d, fid);
+       spin_unlock(&d->opd_pre_lock);
 
        /*
         * probably main thread suspended orphan cleanup till
         * all reservations are released, see comment in
         * osp_precreate_thread() just before orphan cleanup
         */
-       if (unlikely(d->opd_pre_reserved == 0 && d->opd_pre_status))
-               cfs_waitq_signal(&d->opd_pre_waitq);
+       if (unlikely(d->opd_pre_reserved == 0 &&
+                    (d->opd_pre_recovering || d->opd_pre_status)))
+               wake_up(&d->opd_pre_waitq);
 
-       return objid;
+       return 0;
 }
 
 /*
+ * Set size regular attribute on an object
+ *
+ * When a striping is created late, it's possible that size is already
+ * initialized on the file. Then the new striping should inherit size
+ * from the file. The function sets size on the object using the regular
+ * protocol (OST_PUNCH).
+ * XXX: should be re-implemented using OUT ?
  *
+ * \param[in] env      LU environment provided by the caller
+ * \param[in] dt       object
+ * \param[in] size     size to set.
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
  */
 int osp_object_truncate(const struct lu_env *env, struct dt_object *dt,
                        __u64 size)
@@ -809,8 +1641,6 @@ int osp_object_truncate(const struct lu_env *env, struct dt_object *dt,
        if (req == NULL)
                RETURN(-ENOMEM);
 
-       /* XXX: capa support? */
-       /* osc_set_capa_size(req, &RMF_CAPA1, capa); */
        rc = ptlrpc_request_pack(req, LUSTRE_OST_VERSION, OST_PUNCH);
        if (rc) {
                ptlrpc_request_free(req);
@@ -821,6 +1651,13 @@ int osp_object_truncate(const struct lu_env *env, struct dt_object *dt,
         * XXX: decide how do we do here with resend
         * if we don't resend, then client may see wrong file size
         * if we do resend, then MDS thread can get stuck for quite long
+        * and if we don't resend, then client will also get -EWOULDBLOCK !!
+        * (see LU-7975 and sanity/test_27F use cases)
+        * but let's decide not to resend/delay this truncate request to OST
+        * and allow Client to decide to resend, in a less agressive way from
+        * after_reply(), by returning -EINPROGRESS instead of
+        * -EAGAIN/-EWOULDBLOCK upon return from ptlrpc_queue_wait() at the
+        * end of this routine
         */
        req->rq_no_resend = req->rq_no_delay = 1;
 
@@ -831,7 +1668,7 @@ int osp_object_truncate(const struct lu_env *env, struct dt_object *dt,
        if (oa == NULL)
                GOTO(out, rc = -ENOMEM);
 
-       rc = fid_ostid_pack(lu_object_fid(&dt->do_lu), &oa->o_oi);
+       rc = fid_to_ostid(lu_object_fid(&dt->do_lu), &oa->o_oi);
        LASSERT(rc == 0);
        oa->o_size = size;
        oa->o_blocks = OBD_OBJECT_EOF;
@@ -840,7 +1677,7 @@ int osp_object_truncate(const struct lu_env *env, struct dt_object *dt,
 
        body = req_capsule_client_get(&req->rq_pill, &RMF_OST_BODY);
        LASSERT(body);
-       lustre_set_wire_obdo(&body->oa, oa);
+       lustre_set_wire_obdo(&req->rq_import->imp_connect_data, &body->oa, oa);
 
        /* XXX: capa support? */
        /* osc_pack_capa(req, body, capa); */
@@ -848,8 +1685,23 @@ int osp_object_truncate(const struct lu_env *env, struct dt_object *dt,
        ptlrpc_request_set_replen(req);
 
        rc = ptlrpc_queue_wait(req);
-       if (rc)
-               CERROR("can't punch object: %d\n", rc);
+       if (rc) {
+               /* -EWOULDBLOCK/-EAGAIN means OST is unreachable at the moment
+                * since we have decided not to resend/delay, but this could
+                * lead to wrong size to be seen at Client side and even process
+                * trying to open to exit/fail if not itself handling -EAGAIN.
+                * So it should be better to return -EINPROGRESS instead and
+                * leave the decision to resend at Client side in after_reply()
+                */
+               if (rc == -EWOULDBLOCK) {
+                       rc = -EINPROGRESS;
+                       CDEBUG(D_HA, "returning -EINPROGRESS instead of "
+                              "-EWOULDBLOCK/-EAGAIN to allow Client to "
+                              "resend\n");
+               } else {
+                       CERROR("can't punch object: %d\n", rc);
+               }
+       }
 out:
        ptlrpc_req_finished(req);
        if (oa)
@@ -857,46 +1709,101 @@ out:
        RETURN(rc);
 }
 
+/**
+ * Initialize precreation functionality of OSP
+ *
+ * Prepares all the internal structures and starts the precreate thread
+ *
+ * \param[in] d                OSP device
+ *
+ * \retval 0           on success
+ * \retval negative    negated errno on error
+ */
 int osp_init_precreate(struct osp_device *d)
 {
-       struct l_wait_info       lwi = { 0 };
-       int                      rc;
-
        ENTRY;
 
+       OBD_ALLOC_PTR(d->opd_pre);
+       if (d->opd_pre == NULL)
+               RETURN(-ENOMEM);
+
        /* initially precreation isn't ready */
+       init_waitqueue_head(&d->opd_pre_user_waitq);
        d->opd_pre_status = -EAGAIN;
-       d->opd_pre_used_id = 0;
-       d->opd_pre_last_created = 0;
+       fid_zero(&d->opd_pre_used_fid);
+       d->opd_pre_used_fid.f_oid = 1;
+       fid_zero(&d->opd_pre_last_created_fid);
+       d->opd_pre_last_created_fid.f_oid = 1;
+       d->opd_last_id = 0;
        d->opd_pre_reserved = 0;
        d->opd_got_disconnected = 1;
-       d->opd_pre_grow_slow = 0;
-       d->opd_pre_grow_count = OST_MIN_PRECREATE;
-       d->opd_pre_min_grow_count = OST_MIN_PRECREATE;
-       d->opd_pre_max_grow_count = OST_MAX_PRECREATE;
+       d->opd_pre_create_slow = 0;
+       d->opd_pre_create_count = OST_MIN_PRECREATE;
+       d->opd_pre_min_create_count = OST_MIN_PRECREATE;
+       d->opd_pre_max_create_count = OST_MAX_PRECREATE;
+       d->opd_reserved_mb_high = 0;
+       d->opd_reserved_mb_low = 0;
+
+       RETURN(0);
+}
+
+/**
+ * Finish precreate functionality of OSP
+ *
+ *
+ * Asks all the activity (the thread, update timer) to stop, then
+ * wait till that is done.
+ *
+ * \param[in] d                OSP device
+ */
+void osp_precreate_fini(struct osp_device *d)
+{
+       ENTRY;
 
-       cfs_spin_lock_init(&d->opd_pre_lock);
-       cfs_waitq_init(&d->opd_pre_waitq);
-       cfs_waitq_init(&d->opd_pre_user_waitq);
-       cfs_waitq_init(&d->opd_pre_thread.t_ctl_waitq);
+       if (d->opd_pre == NULL)
+               RETURN_EXIT;
+
+       OBD_FREE_PTR(d->opd_pre);
+       d->opd_pre = NULL;
+
+       EXIT;
+}
+
+int osp_init_statfs(struct osp_device *d)
+{
+       struct l_wait_info       lwi = { 0 };
+       struct task_struct              *task;
+
+       ENTRY;
+
+       spin_lock_init(&d->opd_pre_lock);
+       init_waitqueue_head(&d->opd_pre_waitq);
+       thread_set_flags(&d->opd_pre_thread, SVC_INIT);
+       init_waitqueue_head(&d->opd_pre_thread.t_ctl_waitq);
 
        /*
         * Initialize statfs-related things
         */
-       d->opd_statfs_maxage = 5; /* default update interval */
-       d->opd_statfs_fresh_till = cfs_time_shift(-1000);
-       CDEBUG(D_OTHER, "current %llu, fresh till %llu\n",
-              (unsigned long long)cfs_time_current(),
-              (unsigned long long)d->opd_statfs_fresh_till);
-       cfs_timer_init(&d->opd_statfs_timer, osp_statfs_timer_cb, d);
+       d->opd_statfs_maxage = 5; /* defaultupdate interval */
+       d->opd_statfs_fresh_till = ktime_sub_ns(ktime_get(),
+                                               1000 * NSEC_PER_SEC);
+       CDEBUG(D_OTHER, "current %lldns, fresh till %lldns\n",
+              ktime_get_ns(),
+              ktime_to_ns(d->opd_statfs_fresh_till));
+       cfs_timer_setup(&d->opd_statfs_timer, osp_statfs_timer_cb,
+                       (unsigned long)d, 0);
+
+       if (d->opd_storage->dd_rdonly)
+               RETURN(0);
 
        /*
         * start thread handling precreation and statfs updates
         */
-       rc = cfs_create_thread(osp_precreate_thread, d, 0);
-       if (rc < 0) {
-               CERROR("can't start precreate thread %d\n", rc);
-               RETURN(rc);
+       task = kthread_run(osp_precreate_thread, d,
+                          "osp-pre-%u-%u", d->opd_index, d->opd_group);
+       if (IS_ERR(task)) {
+               CERROR("can't start precreate thread %ld\n", PTR_ERR(task));
+               RETURN(PTR_ERR(task));
        }
 
        l_wait_event(d->opd_pre_thread.t_ctl_waitq,
@@ -906,19 +1813,18 @@ int osp_init_precreate(struct osp_device *d)
        RETURN(0);
 }
 
-void osp_precreate_fini(struct osp_device *d)
+void osp_statfs_fini(struct osp_device *d)
 {
        struct ptlrpc_thread *thread = &d->opd_pre_thread;
-
        ENTRY;
 
-       cfs_timer_disarm(&d->opd_statfs_timer);
-
-       thread->t_flags = SVC_STOPPING;
-       cfs_waitq_signal(&d->opd_pre_waitq);
+       del_timer(&d->opd_statfs_timer);
 
-       cfs_wait_event(thread->t_ctl_waitq, thread->t_flags & SVC_STOPPED);
+       if (!thread_is_init(thread) && !thread_is_stopped(thread)) {
+               thread->t_flags = SVC_STOPPING;
+               wake_up(&d->opd_pre_waitq);
+               wait_event(thread->t_ctl_waitq, thread_is_stopped(thread));
+       }
 
        EXIT;
 }
-