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LU-9330 osp: make variables match proc tunables
[fs/lustre-release.git] / lustre / osp / osp_precreate.c
index cac5bf2..c88eeb1 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
  */
@@ -27,7 +23,7 @@
  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2012, 2014, Intel Corporation.
+ * Copyright (c) 2012, 2016, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -45,6 +41,9 @@
 #define DEBUG_SUBSYSTEM S_MDS
 
 #include <linux/kthread.h>
+
+#include <lustre_obdo.h>
+
 #include "osp_internal.h"
 
 /*
@@ -53,7 +52,7 @@
  * = 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
  *
  */
 
@@ -142,7 +141,7 @@ static int osp_statfs_interpret(const struct lu_env *env,
 
        /* 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);
+       mod_timer(&d->opd_statfs_timer, d->opd_statfs_fresh_till);
        d->opd_statfs_update_in_progress = 0;
 
        CDEBUG(D_CACHE, "updated statfs %p\n", d);
@@ -203,7 +202,7 @@ static int osp_statfs_update(struct osp_device *d)
        /*
         * no updates till reply
         */
-       cfs_timer_disarm(&d->opd_statfs_timer);
+       del_timer(&d->opd_statfs_timer);
        d->opd_statfs_fresh_till = cfs_time_shift(obd_timeout * 1000);
        d->opd_statfs_update_in_progress = 1;
 
@@ -234,29 +233,12 @@ void osp_statfs_need_now(struct osp_device *d)
                 * is replied
                 */
                d->opd_statfs_fresh_till = cfs_time_shift(-1);
-               cfs_timer_disarm(&d->opd_statfs_timer);
+               del_timer(&d->opd_statfs_timer);
                wake_up(&d->opd_pre_waitq);
        }
 }
 
 /**
- * Return number of precreated objects
- *
- * 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_objs_precreated(const struct lu_env *env,
-                                     struct osp_device *osp)
-{
-       return osp_fid_diff(&osp->opd_pre_last_created_fid,
-                           &osp->opd_pre_used_fid);
-}
-
-/**
  * Check pool of precreated objects is nearly empty
  *
  * We should not wait till the pool of the precreated objects is exhausted,
@@ -277,7 +259,7 @@ static inline int osp_precreate_near_empty_nolock(const struct lu_env *env,
 
        /* 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));
 }
 
@@ -355,6 +337,9 @@ int osp_write_last_oid_seq_files(struct lu_env *env, struct osp_device *osp,
        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. */
        lb_oid->lb_buf = &fid->f_oid;
@@ -450,7 +435,7 @@ static int osp_precreate_rollover_new_seq(struct lu_env *env,
                RETURN(rc);
        }
 
-       LCONSOLE_INFO("%s: update sequence from "LPX64" to "LPX64"\n",
+       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 */
@@ -492,16 +477,17 @@ static int osp_precreate_fids(const struct lu_env *env, struct osp_device *osp,
        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);
-               ostid_set_id(oi, ostid_id(oi) + *grow);
+               rc = ostid_set_id(oi, ostid_id(oi) + *grow);
                spin_unlock(&osp->opd_pre_lock);
 
-               if (*grow == 0)
+               if (*grow == 0 || rc)
                        return 1;
 
                ostid_to_fid(fid, oi, osp->opd_index);
@@ -575,9 +561,9 @@ static int osp_precreate_send(const struct lu_env *env, struct osp_device *d)
        }
 
        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;
+       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);
@@ -607,6 +593,9 @@ static int osp_precreate_send(const struct lu_env *env, struct osp_device *d)
 
        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,
@@ -620,6 +609,8 @@ static int osp_precreate_send(const struct lu_env *env, struct osp_device *d)
                GOTO(out_req, rc = -EPROTO);
 
        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,
@@ -633,13 +624,13 @@ static int osp_precreate_send(const struct lu_env *env, struct osp_device *d)
        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;
        }
 
        body = req_capsule_client_get(&req->rq_pill, &RMF_OST_BODY);
@@ -767,6 +758,7 @@ static int osp_precreate_cleanup_orphans(struct lu_env *env,
 {
        struct osp_thread_info  *osi = osp_env_info(env);
        struct lu_fid           *last_fid = &osi->osi_fid;
+       struct lu_fid            tmp;
        struct ptlrpc_request   *req = NULL;
        struct obd_import       *imp;
        struct ost_body         *body;
@@ -779,24 +771,15 @@ static int osp_precreate_cleanup_orphans(struct lu_env *env,
 
        /*
         * 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.
+        * orphans are all objects since "last used" (assigned). we do not
+        * block waiting for all reservations as this can lead to a deadlock
+        * see LU-8972 for the details.
         */
        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) ||
+
+       l_wait_event(d->opd_pre_waitq, d->opd_recovery_completed ||
                     !osp_precreate_running(d) || d->opd_got_disconnected,
                     &lwi);
        if (!osp_precreate_running(d) || d->opd_got_disconnected)
@@ -810,6 +793,7 @@ static int osp_precreate_cleanup_orphans(struct lu_env *env,
        LASSERT(!fid_is_zero(last_fid));
        if (fid_oid(&d->opd_last_used_fid) < 2) {
                /* lastfid looks strange... ask OST */
+               LCONSOLE_WARN("%s: refresh last id\n", d->opd_obd->obd_name);
                rc = osp_get_lastfid_from_ost(env, d);
                if (rc)
                        GOTO(out, rc);
@@ -836,7 +820,21 @@ static int osp_precreate_cleanup_orphans(struct lu_env *env,
        body->oa.o_flags = OBD_FL_DELORPHAN;
        body->oa.o_valid = OBD_MD_FLFLAGS | OBD_MD_FLGROUP;
 
-       fid_to_ostid(&d->opd_last_used_fid, &body->oa.o_oi);
+       /* cleanup objects upto used+reserved as we do not
+        * want to block the orphan cleanup procedure */
+       spin_lock(&d->opd_pre_lock);
+       if (fid_seq(&d->opd_pre_used_fid) != 0) {
+               tmp = d->opd_pre_used_fid;
+               tmp.f_oid += d->opd_pre_reserved;
+               /* shrink current precreate window to let reserved
+                * already objects be created and block new
+                * precreations */
+               d->opd_pre_last_created_fid = tmp;
+       } else {
+               tmp = d->opd_last_used_fid;
+       }
+       fid_to_ostid(&tmp, &body->oa.o_oi);
+       spin_unlock(&d->opd_pre_lock);
 
        ptlrpc_request_set_replen(req);
 
@@ -853,30 +851,9 @@ static int osp_precreate_cleanup_orphans(struct lu_env *env,
        if (body == NULL)
                GOTO(out, rc = -EPROTO);
 
-       /*
-        * OST provides us with id new pool starts from in body->oa.o_id
-        */
+       /* OST provides us with id new pool starts from in body->oa.o_id */
        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_grow_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_fid = *last_fid;
-       }
-       /*
-        * 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_grow_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));
@@ -884,10 +861,6 @@ out:
        if (req)
                ptlrpc_req_finished(req);
 
-       spin_lock(&d->opd_pre_lock);
-       d->opd_pre_recovering = 0;
-       spin_unlock(&d->opd_pre_lock);
-
        /*
         * If rc is zero, the pre-creation window should have been emptied.
         * Since waking up the herd would be useless without pre-created
@@ -906,8 +879,41 @@ out:
                } else {
                        wake_up(&d->opd_pre_user_waitq);
                }
+               GOTO(ret, rc);
+       }
+
+       spin_lock(&d->opd_pre_lock);
+       d->opd_pre_recovering = 0;
+       spin_unlock(&d->opd_pre_lock);
+
+       /* now we wait until all reserved objects are consumed or released,
+        * so that the window doesn't change. otherwise we can get objects
+        * with wrong FIDs */
+       l_wait_event(d->opd_pre_waitq, d->opd_pre_reserved == 0 ||
+                    !osp_precreate_running(d) || d->opd_got_disconnected, &lwi);
+       if (!osp_precreate_running(d))
+               GOTO(ret, rc = 0);
+
+       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_create_count = OST_MIN_PRECREATE;
+               d->opd_pre_last_created_fid = *last_fid;
        }
+       /*
+        * 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);
 
+ret:
        RETURN(rc);
 }
 
@@ -923,17 +929,8 @@ out:
  * 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 NOSPC flag when there is less than ~0.1% free
- * and clear it when there is at least ~0.2% free space, so:
- *                   avail < ~0.1% max          max = avail + used
- *            1025 * avail < avail + used       used = blocks - free
- *            1024 * avail < used
- *            1024 * avail < blocks - free
- *                   avail < ((blocks - free) >> 10)
- *
- * On very large disk, say 16TB 0.1% will be 16 GB. We don't want to
- * lose that amount of space so in those cases we report no space left
- * if their is less than 1 GB left.
+ * We want to set the ENOSPC when there is less than reserved size
+ * free and clear it when there is at least 2*reserved size free space.
  * the function updates current precreation status used: functional or not
  *
  * \param[in] d                OSP device
@@ -946,42 +943,72 @@ void osp_pre_update_status(struct osp_device *d, int rc)
 {
        struct obd_statfs       *msfs = &d->opd_statfs;
        int                      old = d->opd_pre_status;
-       __u64                    used;
+       __u64                    available;
 
        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)) {
+               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);
+               }
+               /* in MB */
+               available = (msfs->os_bavail * (msfs->os_bsize >> 10)) >> 10;
+               if (msfs->os_ffree < 32)
+                       msfs->os_state |= OS_STATE_ENOINO;
+               else if (msfs->os_ffree > 64)
+                       msfs->os_state &= ~OS_STATE_ENOINO;
+
+               if (available < d->opd_reserved_mb_low)
+                       msfs->os_state |= OS_STATE_ENOSPC;
+               else if (available > d->opd_reserved_mb_high)
+                       msfs->os_state &= ~OS_STATE_ENOSPC;
+               if (msfs->os_state & (OS_STATE_ENOINO | OS_STATE_ENOSPC)) {
                        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",
+                               CDEBUG(D_INFO, "%s: status: %llu blocks, %llu "
+                                      "free, %llu avail, %llu MB avail, %u "
+                                      "hwm -> %d: rc = %d\n",
                                       d->opd_obd->obd_name, msfs->os_blocks,
-                                      msfs->os_bfree, used, msfs->os_bavail,
+                                      msfs->os_bfree, msfs->os_bavail,
+                                      available, d->opd_reserved_mb_high,
                                       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) {
+                              "non-committed changes: %u, in progress: %u\n",
+                              atomic_read(&d->opd_sync_changes),
+                              atomic_read(&d->opd_sync_rpcs_in_progress));
+               } else if (unlikely(old == -ENOSPC)) {
                        d->opd_pre_status = 0;
                        spin_lock(&d->opd_pre_lock);
-                       d->opd_pre_grow_slow = 0;
-                       d->opd_pre_grow_count = OST_MIN_PRECREATE;
+                       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: 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);
+
+                       CDEBUG(D_INFO, "%s: space available: %llu blocks, %llu"
+                              " free, %llu avail, %lluMB avail, %u lwm"
+                              " -> %d: rc = %d\n", d->opd_obd->obd_name,
+                              msfs->os_blocks, msfs->os_bfree, msfs->os_bavail,
+                              available, d->opd_reserved_mb_low,
+                              d->opd_pre_status, rc);
                }
        }
-
 out:
        wake_up(&d->opd_pre_user_waitq);
 }
@@ -1013,9 +1040,27 @@ int osp_init_pre_fid(struct osp_device *osp)
 
        LASSERT(osp->opd_pre != NULL);
 
-       /* Return if last_used fid has been initialized */
+       /* 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))
-               RETURN(0);
+               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) {
@@ -1081,6 +1126,8 @@ 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 };
+       struct l_wait_info       lwi2 = LWI_TIMEOUT(cfs_time_seconds(5),
+                                                   back_to_sleep, NULL);
        struct lu_env            env;
        int                      rc;
 
@@ -1090,6 +1137,12 @@ static int osp_precreate_thread(void *_arg)
        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);
        }
 
@@ -1103,6 +1156,10 @@ static int osp_precreate_thread(void *_arg)
                 * need to be connected to OST
                 */
                while (osp_precreate_running(d)) {
+                       if (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,
@@ -1134,14 +1191,20 @@ static int osp_precreate_thread(void *_arg)
                        continue;
                }
 
-               osp_statfs_update(d);
+               if (osp_statfs_update(d)) {
+                       l_wait_event(d->opd_pre_waitq,
+                                    !osp_precreate_running(d), &lwi2);
+                       continue;
+               }
 
                /*
                 * Clean up orphans or recreate missing objects.
                 */
                rc = osp_precreate_cleanup_orphans(&env, d);
-               if (rc != 0)
+               if (rc != 0) {
+                       schedule_timeout_interruptible(cfs_time_seconds(1));
                        continue;
+               }
                /*
                 * connected, can handle precreates now
                 */
@@ -1161,7 +1224,8 @@ static int osp_precreate_thread(void *_arg)
                                break;
 
                        if (osp_statfs_need_update(d))
-                               osp_statfs_update(d);
+                               if (osp_statfs_update(d))
+                                       break;
 
                        /* To avoid handling different seq in precreate/orphan
                         * cleanup, it will hold precreate until current seq is
@@ -1172,7 +1236,7 @@ static int osp_precreate_thread(void *_arg)
 
                        if (unlikely(osp_precreate_end_seq(&env, d) &&
                                     osp_create_end_seq(&env, d))) {
-                               LCONSOLE_INFO("%s:"LPX64" is used up."
+                               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));
@@ -1228,7 +1292,8 @@ static int osp_precreate_ready_condition(const struct lu_env *env,
                return 1;
 
        /* ready if OST reported no space and no destroys in progress */
-       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 &&
            d->opd_pre_status == -ENOSPC)
                return 1;
 
@@ -1236,6 +1301,7 @@ static int osp_precreate_ready_condition(const struct lu_env *env,
        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)
@@ -1252,11 +1318,12 @@ static int osp_precreate_timeout_condition(void *data)
        struct osp_device *d = data;
 
        CDEBUG(D_HA, "%s: slow creates, last="DFID", next="DFID", "
-             "reserved="LPU64", syn_changes=%lu, "
-             "syn_rpc_in_progress=%d, status=%d\n",
+             "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,
-             d->opd_syn_changes, d->opd_syn_rpc_in_progress,
+             atomic_read(&d->opd_sync_changes),
+             atomic_read(&d->opd_sync_rpcs_in_progress),
              d->opd_pre_status);
 
        return 1;
@@ -1298,6 +1365,16 @@ int osp_precreate_reserve(const struct lu_env *env, struct osp_device *d)
                 "Next FID "DFID"\n", PFID(&d->opd_pre_last_created_fid),
                 PFID(&d->opd_pre_used_fid));
 
+       /* opd_pre_max_create_count 0 to not use specified OST. */
+       if (d->opd_pre_max_create_count == 0)
+               RETURN(-ENOBUFS);
+
+       if (OBD_FAIL_PRECHECK(OBD_FAIL_MDS_OSP_PRECREATE_WAIT)) {
+               if (d->opd_index == cfs_fail_val)
+                       OBD_FAIL_TIMEOUT(OBD_FAIL_MDS_OSP_PRECREATE_WAIT,
+                                        obd_timeout);
+       }
+
        /*
         * wait till:
         *  - preallocation is done
@@ -1312,12 +1389,12 @@ int osp_precreate_reserve(const struct lu_env *env, struct osp_device *d)
                 * increase number of precreations
                 */
                precreated = osp_objs_precreated(env, d);
-               if (d->opd_pre_grow_count < d->opd_pre_max_grow_count &&
-                   d->opd_pre_grow_slow == 0 &&
-                   precreated <= (d->opd_pre_grow_count / 4 + 1)) {
+               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_grow_slow = 1;
-                       d->opd_pre_grow_count *= 2;
+                       d->opd_pre_create_slow = 1;
+                       d->opd_pre_create_count *= 2;
                        spin_unlock(&d->opd_pre_lock);
                }
 
@@ -1345,16 +1422,16 @@ 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)) {
                                /* force local commit to release space */
                                dt_commit_async(env, d->opd_storage);
                        }
-                       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;
                        }
@@ -1479,6 +1556,13 @@ 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;
 
@@ -1506,8 +1590,23 @@ 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)
@@ -1544,14 +1643,17 @@ int osp_init_precreate(struct osp_device *d)
        d->opd_pre_last_created_fid.f_oid = 1;
        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;
 
        spin_lock_init(&d->opd_pre_lock);
        init_waitqueue_head(&d->opd_pre_waitq);
        init_waitqueue_head(&d->opd_pre_user_waitq);
+       thread_set_flags(&d->opd_pre_thread, SVC_INIT);
        init_waitqueue_head(&d->opd_pre_thread.t_ctl_waitq);
 
        /*
@@ -1562,7 +1664,11 @@ int osp_init_precreate(struct osp_device *d)
        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);
+       setup_timer(&d->opd_statfs_timer, osp_statfs_timer_cb,
+                   (unsigned long)d);
+
+       if (d->opd_storage->dd_rdonly)
+               RETURN(0);
 
        /*
         * start thread handling precreation and statfs updates
@@ -1592,21 +1698,19 @@ int osp_init_precreate(struct osp_device *d)
  */
 void osp_precreate_fini(struct osp_device *d)
 {
-       struct ptlrpc_thread *thread;
-
+       struct ptlrpc_thread *thread = &d->opd_pre_thread;
        ENTRY;
 
-       cfs_timer_disarm(&d->opd_statfs_timer);
+       del_timer(&d->opd_statfs_timer);
 
        if (d->opd_pre == NULL)
                RETURN_EXIT;
 
-       thread = &d->opd_pre_thread;
-
-       thread->t_flags = SVC_STOPPING;
-       wake_up(&d->opd_pre_waitq);
-
-       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));
+       }
 
        OBD_FREE_PTR(d->opd_pre);
        d->opd_pre = NULL;