Whamcloud - gitweb
LU-3963 obdclass: convert to linux list api
[fs/lustre-release.git] / lustre / obdclass / cl_io.c
index fffe551..8878ed8 100644 (file)
@@ -1,6 +1,4 @@
-/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
- * vim:expandtab:shiftwidth=8:tabstop=8:
- *
+/*
  * GPL HEADER START
  *
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  * GPL HEADER END
  */
 /*
- * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
+ *
+ * Copyright (c) 2011, 2013, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
  * Client IO.
  *
  *   Author: Nikita Danilov <nikita.danilov@sun.com>
+ *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  */
 
 #define DEBUG_SUBSYSTEM S_CLASS
-#ifndef EXPORT_SYMTAB
-# define EXPORT_SYMTAB
-#endif
 
 #include <obd_class.h>
 #include <obd_support.h>
 #include <lustre_fid.h>
 #include <libcfs/list.h>
-/* lu_time_global_{init,fini}() */
-#include <lu_time.h>
-
 #include <cl_object.h>
 #include "cl_internal.h"
 
@@ -60,9 +55,9 @@
  */
 
 #define cl_io_for_each(slice, io) \
-        list_for_each_entry((slice), &io->ci_layers, cis_linkage)
+       list_for_each_entry((slice), &io->ci_layers, cis_linkage)
 #define cl_io_for_each_reverse(slice, io)                 \
-        list_for_each_entry_reverse((slice), &io->ci_layers, cis_linkage)
+       list_for_each_entry_reverse((slice), &io->ci_layers, cis_linkage)
 
 static inline int cl_io_type_is_valid(enum cl_io_type type)
 {
@@ -107,17 +102,17 @@ static int cl_io_invariant(const struct cl_io *io)
  */
 void cl_io_fini(const struct lu_env *env, struct cl_io *io)
 {
-        struct cl_io_slice    *slice;
-        struct cl_thread_info *info;
+       struct cl_io_slice    *slice;
+       struct cl_thread_info *info;
 
         LINVRNT(cl_io_type_is_valid(io->ci_type));
         LINVRNT(cl_io_invariant(io));
         ENTRY;
 
-        while (!list_empty(&io->ci_layers)) {
-                slice = container_of(io->ci_layers.next, struct cl_io_slice,
+       while (!list_empty(&io->ci_layers)) {
+                slice = container_of(io->ci_layers.prev, struct cl_io_slice,
                                      cis_linkage);
-                list_del_init(&slice->cis_linkage);
+               list_del_init(&slice->cis_linkage);
                 if (slice->cis_iop->op[io->ci_type].cio_fini != NULL)
                         slice->cis_iop->op[io->ci_type].cio_fini(env, slice);
                 /*
@@ -131,7 +126,26 @@ void cl_io_fini(const struct lu_env *env, struct cl_io *io)
         info = cl_env_info(env);
         if (info->clt_current_io == io)
                 info->clt_current_io = NULL;
-        EXIT;
+
+       /* sanity check for layout change */
+       switch(io->ci_type) {
+       case CIT_READ:
+       case CIT_WRITE:
+               break;
+       case CIT_FAULT:
+       case CIT_FSYNC:
+               LASSERT(!io->ci_need_restart);
+               break;
+       case CIT_SETATTR:
+       case CIT_MISC:
+               /* Check ignore layout change conf */
+               LASSERT(ergo(io->ci_ignore_layout || !io->ci_verify_layout,
+                               !io->ci_need_restart));
+               break;
+       default:
+               LBUG();
+       }
+       EXIT;
 }
 EXPORT_SYMBOL(cl_io_fini);
 
@@ -147,10 +161,10 @@ static int cl_io_init0(const struct lu_env *env, struct cl_io *io,
         ENTRY;
 
         io->ci_type = iot;
-        CFS_INIT_LIST_HEAD(&io->ci_lockset.cls_todo);
-        CFS_INIT_LIST_HEAD(&io->ci_lockset.cls_curr);
-        CFS_INIT_LIST_HEAD(&io->ci_lockset.cls_done);
-        CFS_INIT_LIST_HEAD(&io->ci_layers);
+       INIT_LIST_HEAD(&io->ci_lockset.cls_todo);
+       INIT_LIST_HEAD(&io->ci_lockset.cls_curr);
+       INIT_LIST_HEAD(&io->ci_lockset.cls_done);
+       INIT_LIST_HEAD(&io->ci_layers);
 
         result = 0;
         cl_object_for_each(scan, obj) {
@@ -233,13 +247,41 @@ cl_lock_descr_fid(const struct cl_lock_descr *descr)
         return lu_object_fid(&descr->cld_obj->co_lu);
 }
 
-static int cl_lock_descr_cmp(const struct cl_lock_descr *d0,
-                             const struct cl_lock_descr *d1)
+static int cl_lock_descr_sort(const struct cl_lock_descr *d0,
+                              const struct cl_lock_descr *d1)
 {
         return lu_fid_cmp(cl_lock_descr_fid(d0), cl_lock_descr_fid(d1)) ?:
                 __diff_normalize(d0->cld_start, d1->cld_start);
 }
 
+static int cl_lock_descr_cmp(const struct cl_lock_descr *d0,
+                             const struct cl_lock_descr *d1)
+{
+        int ret;
+
+        ret = lu_fid_cmp(cl_lock_descr_fid(d0), cl_lock_descr_fid(d1));
+        if (ret)
+                return ret;
+        if (d0->cld_end < d1->cld_start)
+                return -1;
+        if (d0->cld_start > d0->cld_end)
+                return 1;
+        return 0;
+}
+
+static void cl_lock_descr_merge(struct cl_lock_descr *d0,
+                                const struct cl_lock_descr *d1)
+{
+        d0->cld_start = min(d0->cld_start, d1->cld_start);
+        d0->cld_end = max(d0->cld_end, d1->cld_end);
+
+        if (d1->cld_mode == CLM_WRITE && d0->cld_mode != CLM_WRITE)
+                d0->cld_mode = CLM_WRITE;
+
+        if (d1->cld_mode == CLM_GROUP && d0->cld_mode != CLM_GROUP)
+                d0->cld_mode = CLM_GROUP;
+}
+
 /*
  * Sort locks in lexicographical order of their (fid, start-offset) pairs.
  */
@@ -257,33 +299,33 @@ static void cl_io_locks_sort(struct cl_io *io)
                 done = 1;
                 prev = NULL;
 
-                list_for_each_entry_safe(curr, temp, &io->ci_lockset.cls_todo,
-                                         cill_linkage) {
-                        if (prev != NULL) {
-                                switch (cl_lock_descr_cmp(&prev->cill_descr,
-                                                          &curr->cill_descr)) {
-                                case 0:
-                                        /*
-                                         * IMPOSSIBLE: Identical locks are
-                                         *             already removed at
-                                         *             this point.
-                                         */
-                                default:
-                                        LBUG();
-                                case +1:
-                                        list_move_tail(&curr->cill_linkage,
-                                                       &prev->cill_linkage);
-                                        done = 0;
-                                        continue; /* don't change prev: it's
-                                                   * still "previous" */
-                                case -1: /* already in order */
-                                        break;
-                                }
-                        }
-                        prev = curr;
-                }
-        } while (!done);
-        EXIT;
+               list_for_each_entry_safe(curr, temp, &io->ci_lockset.cls_todo,
+                                        cill_linkage) {
+                       if (prev != NULL) {
+                               switch (cl_lock_descr_sort(&prev->cill_descr,
+                                                          &curr->cill_descr)) {
+                               case 0:
+                                       /*
+                                        * IMPOSSIBLE:  Identical locks are
+                                                     already removed at
+                                                     this point.
+                                        */
+                               default:
+                                       LBUG();
+                               case +1:
+                                       list_move_tail(&curr->cill_linkage,
+                                                      &prev->cill_linkage);
+                                       done = 0;
+                                       continue; /* don't change prev: it's
+                                                  * still "previous" */
+                               case -1: /* already in order */
+                                       break;
+                               }
+                       }
+                       prev = curr;
+               }
+       } while (!done);
+       EXIT;
 }
 
 /**
@@ -295,23 +337,47 @@ static void cl_io_locks_sort(struct cl_io *io)
 int cl_queue_match(const struct list_head *queue,
                    const struct cl_lock_descr *need)
 {
-       struct cl_io_lock_link *scan;
+       struct cl_io_lock_link *scan;
+       ENTRY;
 
-       ENTRY;
-       list_for_each_entry(scan, queue, cill_linkage) {
-               if (cl_lock_descr_match(&scan->cill_descr, need))
-                       RETURN(+1);
-       }
-       return 0;
+       list_for_each_entry(scan, queue, cill_linkage) {
+               if (cl_lock_descr_match(&scan->cill_descr, need))
+                       RETURN(+1);
+       }
+       RETURN(0);
 }
 EXPORT_SYMBOL(cl_queue_match);
 
+static int cl_queue_merge(const struct list_head *queue,
+                          const struct cl_lock_descr *need)
+{
+       struct cl_io_lock_link *scan;
+       ENTRY;
+
+       list_for_each_entry(scan, queue, cill_linkage) {
+               if (cl_lock_descr_cmp(&scan->cill_descr, need))
+                       continue;
+               cl_lock_descr_merge(&scan->cill_descr, need);
+               CDEBUG(D_VFSTRACE, "lock: %d: [%lu, %lu]\n",
+                      scan->cill_descr.cld_mode, scan->cill_descr.cld_start,
+                      scan->cill_descr.cld_end);
+               RETURN(+1);
+       }
+       RETURN(0);
+}
+
 static int cl_lockset_match(const struct cl_lockset *set,
-                            const struct cl_lock_descr *need, int all_queues)
+                            const struct cl_lock_descr *need)
+{
+        return cl_queue_match(&set->cls_curr, need) ||
+               cl_queue_match(&set->cls_done, need);
+}
+
+static int cl_lockset_merge(const struct cl_lockset *set,
+                            const struct cl_lock_descr *need)
 {
-        return (all_queues ? cl_queue_match(&set->cls_todo, need) : 0) ||
-                cl_queue_match(&set->cls_curr, need) ||
-                cl_queue_match(&set->cls_done, need);
+        return cl_queue_merge(&set->cls_todo, need) ||
+               cl_lockset_match(set, need);
 }
 
 static int cl_lockset_lock_one(const struct lu_env *env,
@@ -323,15 +389,15 @@ static int cl_lockset_lock_one(const struct lu_env *env,
 
         ENTRY;
 
-        lock = cl_lock_request(env, io, &link->cill_descr, link->cill_enq_flags,
-                               "io", io);
+       lock = cl_lock_request(env, io, &link->cill_descr, "io", io);
+
         if (!IS_ERR(lock)) {
                 link->cill_lock = lock;
-                list_move(&link->cill_linkage, &set->cls_curr);
-                if (!(link->cill_enq_flags & CEF_ASYNC)) {
+               list_move(&link->cill_linkage, &set->cls_curr);
+                if (!(link->cill_descr.cld_enq_flags & CEF_ASYNC)) {
                         result = cl_wait(env, lock);
                         if (result == 0)
-                                list_move(&link->cill_linkage, &set->cls_done);
+                               list_move(&link->cill_linkage, &set->cls_done);
                 } else
                         result = 0;
         } else
@@ -345,7 +411,7 @@ static void cl_lock_link_fini(const struct lu_env *env, struct cl_io *io,
         struct cl_lock *lock = link->cill_lock;
 
         ENTRY;
-        list_del_init(&link->cill_linkage);
+       list_del_init(&link->cill_linkage);
         if (lock != NULL) {
                 cl_lock_release(env, lock, "io", io);
                 link->cill_lock = NULL;
@@ -358,35 +424,35 @@ static void cl_lock_link_fini(const struct lu_env *env, struct cl_io *io,
 static int cl_lockset_lock(const struct lu_env *env, struct cl_io *io,
                            struct cl_lockset *set)
 {
-        struct cl_io_lock_link *link;
-        struct cl_io_lock_link *temp;
-        struct cl_lock         *lock;
-        int result;
-
-        ENTRY;
-        result = 0;
-        list_for_each_entry_safe(link, temp, &set->cls_todo, cill_linkage) {
-                if (!cl_lockset_match(set, &link->cill_descr, 0)) {
-                        /* XXX some locking to guarantee that locks aren't
-                         * expanded in between. */
-                        result = cl_lockset_lock_one(env, io, set, link);
-                        if (result != 0)
-                                break;
-                } else
-                        cl_lock_link_fini(env, io, link);
-        }
-        if (result == 0) {
-                list_for_each_entry_safe(link, temp,
-                                         &set->cls_curr, cill_linkage) {
-                        lock = link->cill_lock;
-                        result = cl_wait(env, lock);
-                        if (result == 0)
-                                list_move(&link->cill_linkage, &set->cls_done);
-                        else
-                                break;
-                }
-        }
-        RETURN(result);
+       struct cl_io_lock_link  *link;
+       struct cl_io_lock_link  *temp;
+       struct cl_lock          *lock;
+       int result;
+
+       ENTRY;
+       result = 0;
+       list_for_each_entry_safe(link, temp, &set->cls_todo, cill_linkage) {
+               if (!cl_lockset_match(set, &link->cill_descr)) {
+                       /* XXX some locking to guarantee that locks aren't
+                        * expanded in between. */
+                       result = cl_lockset_lock_one(env, io, set, link);
+                       if (result != 0)
+                               break;
+               } else
+                       cl_lock_link_fini(env, io, link);
+       }
+       if (result == 0) {
+               list_for_each_entry_safe(link, temp, &set->cls_curr,
+                                        cill_linkage) {
+                       lock = link->cill_lock;
+                       result = cl_wait(env, lock);
+                       if (result == 0)
+                               list_move(&link->cill_linkage, &set->cls_done);
+                       else
+                               break;
+               }
+       }
+       RETURN(result);
 }
 
 /**
@@ -442,23 +508,23 @@ void cl_io_unlock(const struct lu_env *env, struct cl_io *io)
         ENTRY;
         set = &io->ci_lockset;
 
-        list_for_each_entry_safe(link, temp, &set->cls_todo, cill_linkage)
-                cl_lock_link_fini(env, io, link);
+       list_for_each_entry_safe(link, temp, &set->cls_todo, cill_linkage)
+               cl_lock_link_fini(env, io, link);
 
-        list_for_each_entry_safe(link, temp, &set->cls_curr, cill_linkage)
-                cl_lock_link_fini(env, io, link);
+       list_for_each_entry_safe(link, temp, &set->cls_curr, cill_linkage)
+               cl_lock_link_fini(env, io, link);
 
-        list_for_each_entry_safe(link, temp, &set->cls_done, cill_linkage) {
-                cl_unuse(env, link->cill_lock);
-                cl_lock_link_fini(env, io, link);
-        }
-        cl_io_for_each_reverse(scan, io) {
-                if (scan->cis_iop->op[io->ci_type].cio_unlock != NULL)
-                        scan->cis_iop->op[io->ci_type].cio_unlock(env, scan);
-        }
-        io->ci_state = CIS_UNLOCKED;
-        LASSERT(!cl_env_info(env)->clt_counters[CNL_TOP].ctc_nr_locks_acquired);
-        EXIT;
+       list_for_each_entry_safe(link, temp, &set->cls_done, cill_linkage) {
+               cl_unuse(env, link->cill_lock);
+               cl_lock_link_fini(env, io, link);
+       }
+       cl_io_for_each_reverse(scan, io) {
+               if (scan->cis_iop->op[io->ci_type].cio_unlock != NULL)
+                       scan->cis_iop->op[io->ci_type].cio_unlock(env, scan);
+       }
+       io->ci_state = CIS_UNLOCKED;
+       LASSERT(!cl_env_info(env)->clt_counters[CNL_TOP].ctc_nr_locks_acquired);
+       EXIT;
 }
 EXPORT_SYMBOL(cl_io_unlock);
 
@@ -553,10 +619,10 @@ int cl_io_lock_add(const struct lu_env *env, struct cl_io *io,
         int result;
 
         ENTRY;
-        if (cl_lockset_match(&io->ci_lockset, &link->cill_descr, 1))
+        if (cl_lockset_merge(&io->ci_lockset, &link->cill_descr))
                 result = +1;
         else {
-                list_add(&link->cill_linkage, &io->ci_lockset.cls_todo);
+               list_add(&link->cill_linkage, &io->ci_lockset.cls_todo);
                 result = 0;
         }
         RETURN(result);
@@ -573,7 +639,7 @@ static void cl_free_io_lock_link(const struct lu_env *env,
  * Allocates new lock link, and uses it to add a lock to a lockset.
  */
 int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
-                         struct cl_lock_descr *descr, int enqflags)
+                         struct cl_lock_descr *descr)
 {
         struct cl_io_lock_link *link;
         int result;
@@ -582,7 +648,6 @@ int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
         OBD_ALLOC_PTR(link);
         if (link != NULL) {
                 link->cill_descr     = *descr;
-                link->cill_enq_flags = enqflags;
                 link->cill_fini      = cl_free_io_lock_link;
                 result = cl_io_lock_add(env, io, link);
                 if (result) /* lock match */
@@ -655,38 +720,6 @@ cl_io_slice_page(const struct cl_io_slice *ios, struct cl_page *page)
 }
 
 /**
- * True iff \a page is within \a io range.
- */
-static int cl_page_in_io(const struct cl_page *page, const struct cl_io *io)
-{
-        int     result;
-        loff_t  start;
-        loff_t  end;
-        pgoff_t idx;
-
-        idx = page->cp_index;
-        switch (io->ci_type) {
-        case CIT_READ:
-        case CIT_WRITE:
-                /*
-                 * check that [start, end) and [pos, pos + count) extents
-                 * overlap.
-                 */
-                start = cl_offset(page->cp_obj, idx);
-                end   = cl_offset(page->cp_obj, idx + 1);
-                result = io->u.ci_rw.crw_pos < end &&
-                        start < io->u.ci_rw.crw_pos + io->u.ci_rw.crw_count;
-                break;
-        case CIT_FAULT:
-                result = io->u.ci_fault.ft_index == idx;
-                break;
-        default:
-                LBUG();
-        }
-        return result;
-}
-
-/**
  * Called by read io, when page has to be read from the server.
  *
  * \see cl_io_operations::cio_read_page()
@@ -701,7 +734,6 @@ int cl_io_read_page(const struct lu_env *env, struct cl_io *io,
         LINVRNT(io->ci_type == CIT_READ || io->ci_type == CIT_FAULT);
         LINVRNT(cl_page_is_owned(page, io));
         LINVRNT(io->ci_state == CIS_IO_GOING || io->ci_state == CIS_LOCKED);
-        LINVRNT(cl_page_in_io(page, io));
         LINVRNT(cl_io_invariant(io));
         ENTRY;
 
@@ -729,8 +761,8 @@ int cl_io_read_page(const struct lu_env *env, struct cl_io *io,
                                 break;
                 }
         }
-        if (result == 0)
-                result = cl_io_submit_rw(env, io, CRT_READ, queue, CRP_NORMAL);
+       if (result == 0 && queue->c2_qin.pl_nr > 0)
+               result = cl_io_submit_rw(env, io, CRT_READ, queue);
         /*
          * Unlock unsent pages in case of error.
          */
@@ -741,79 +773,30 @@ int cl_io_read_page(const struct lu_env *env, struct cl_io *io,
 EXPORT_SYMBOL(cl_io_read_page);
 
 /**
- * Called by write io to prepare page to receive data from user buffer.
+ * Commit a list of contiguous pages into writeback cache.
  *
- * \see cl_io_operations::cio_prepare_write()
+ * \returns 0 if all pages committed, or errcode if error occurred.
+ * \see cl_io_operations::cio_commit_async()
  */
-int cl_io_prepare_write(const struct lu_env *env, struct cl_io *io,
-                        struct cl_page *page, unsigned from, unsigned to)
-{
-        const struct cl_io_slice *scan;
-        int result = 0;
-
-        LINVRNT(io->ci_type == CIT_WRITE);
-        LINVRNT(cl_page_is_owned(page, io));
-        LINVRNT(io->ci_state == CIS_IO_GOING || io->ci_state == CIS_LOCKED);
-        LINVRNT(cl_io_invariant(io));
-        LASSERT(cl_page_in_io(page, io));
-        ENTRY;
-
-        cl_io_for_each_reverse(scan, io) {
-                if (scan->cis_iop->cio_prepare_write != NULL) {
-                        const struct cl_page_slice *slice;
-
-                        slice = cl_io_slice_page(scan, page);
-                        result = scan->cis_iop->cio_prepare_write(env, scan,
-                                                                  slice,
-                                                                  from, to);
-                        if (result != 0)
-                                break;
-                }
-        }
-        RETURN(result);
-}
-EXPORT_SYMBOL(cl_io_prepare_write);
-
-/**
- * Called by write io after user data were copied into a page.
- *
- * \see cl_io_operations::cio_commit_write()
- */
-int cl_io_commit_write(const struct lu_env *env, struct cl_io *io,
-                       struct cl_page *page, unsigned from, unsigned to)
-{
-        const struct cl_io_slice *scan;
-        int result = 0;
-
-        LINVRNT(io->ci_type == CIT_WRITE);
-        LINVRNT(io->ci_state == CIS_IO_GOING || io->ci_state == CIS_LOCKED);
-        LINVRNT(cl_io_invariant(io));
-        /*
-         * XXX Uh... not nice. Top level cl_io_commit_write() call (vvp->lov)
-         * already called cl_page_cache_add(), moving page into CPS_CACHED
-         * state. Better (and more general) way of dealing with such situation
-         * is needed.
-         */
-        LASSERT(cl_page_is_owned(page, io) || page->cp_parent != NULL);
-        LASSERT(cl_page_in_io(page, io));
-        ENTRY;
-
-        cl_io_for_each(scan, io) {
-                if (scan->cis_iop->cio_commit_write != NULL) {
-                        const struct cl_page_slice *slice;
-
-                        slice = cl_io_slice_page(scan, page);
-                        result = scan->cis_iop->cio_commit_write(env, scan,
-                                                                 slice,
-                                                                 from, to);
-                        if (result != 0)
-                                break;
-                }
-        }
-        LINVRNT(result <= 0);
-        RETURN(result);
-}
-EXPORT_SYMBOL(cl_io_commit_write);
+int cl_io_commit_async(const struct lu_env *env, struct cl_io *io,
+                       struct cl_page_list *queue, int from, int to,
+                       cl_commit_cbt cb)
+{
+       const struct cl_io_slice *scan;
+       int result = 0;
+       ENTRY;
+
+       cl_io_for_each(scan, io) {
+               if (scan->cis_iop->cio_commit_async == NULL)
+                       continue;
+               result = scan->cis_iop->cio_commit_async(env, scan, queue,
+                                                        from, to, cb);
+               if (result != 0)
+                       break;
+       }
+       RETURN(result);
+}
+EXPORT_SYMBOL(cl_io_commit_async);
 
 /**
  * Submits a list of pages for immediate io.
@@ -826,28 +809,24 @@ EXPORT_SYMBOL(cl_io_commit_write);
  * \see cl_io_operations::cio_submit()
  */
 int cl_io_submit_rw(const struct lu_env *env, struct cl_io *io,
-                    enum cl_req_type crt, struct cl_2queue *queue,
-                    enum cl_req_priority priority)
-{
-        const struct cl_io_slice *scan;
-        int result = 0;
-
-        LINVRNT(crt < ARRAY_SIZE(scan->cis_iop->req_op));
-        ENTRY;
-
-        cl_io_for_each(scan, io) {
-                if (scan->cis_iop->req_op[crt].cio_submit == NULL)
-                        continue;
-                result = scan->cis_iop->req_op[crt].cio_submit(env, scan, crt,
-                                                               queue, priority);
-                if (result != 0)
-                        break;
-        }
-        /*
-         * If ->cio_submit() failed, no pages were sent.
-         */
-        LASSERT(ergo(result != 0, list_empty(&queue->c2_qout.pl_pages)));
-        RETURN(result);
+                   enum cl_req_type crt, struct cl_2queue *queue)
+{
+       const struct cl_io_slice *scan;
+       int result = 0;
+       ENTRY;
+
+       cl_io_for_each(scan, io) {
+               if (scan->cis_iop->cio_submit == NULL)
+                       continue;
+               result = scan->cis_iop->cio_submit(env, scan, crt, queue);
+               if (result != 0)
+                       break;
+       }
+       /*
+        * If ->cio_submit() failed, no pages were sent.
+        */
+       LASSERT(ergo(result != 0, list_empty(&queue->c2_qout.pl_pages)));
+       RETURN(result);
 }
 EXPORT_SYMBOL(cl_io_submit_rw);
 
@@ -857,21 +836,19 @@ EXPORT_SYMBOL(cl_io_submit_rw);
  */
 int cl_io_submit_sync(const struct lu_env *env, struct cl_io *io,
                       enum cl_req_type iot, struct cl_2queue *queue,
-                      enum cl_req_priority prio, long timeout)
+                     long timeout)
 {
         struct cl_sync_io *anchor = &cl_env_info(env)->clt_anchor;
         struct cl_page *pg;
         int rc;
 
-        LASSERT(prio == CRP_NORMAL || prio == CRP_CANCEL);
-
         cl_page_list_for_each(pg, &queue->c2_qin) {
                 LASSERT(pg->cp_sync_io == NULL);
                 pg->cp_sync_io = anchor;
         }
 
         cl_sync_io_init(anchor, queue->c2_qin.pl_nr);
-        rc = cl_io_submit_rw(env, io, iot, queue, prio);
+       rc = cl_io_submit_rw(env, io, iot, queue);
         if (rc == 0) {
                 /*
                  * If some pages weren't sent for any reason (e.g.,
@@ -888,7 +865,7 @@ int cl_io_submit_sync(const struct lu_env *env, struct cl_io *io,
                  rc = cl_sync_io_wait(env, io, &queue->c2_qout,
                                       anchor, timeout);
         } else {
-                LASSERT(list_empty(&queue->c2_qout.pl_pages));
+               LASSERT(list_empty(&queue->c2_qout.pl_pages));
                 cl_page_list_for_each(pg, &queue->c2_qin)
                         pg->cp_sync_io = NULL;
         }
@@ -909,7 +886,6 @@ int cl_io_cancel(const struct lu_env *env, struct cl_io *io,
         cl_page_list_for_each(page, queue) {
                 int rc;
 
-                LINVRNT(cl_page_in_io(page, io));
                 rc = cl_page_cancel(env, page);
                 result = result ?: rc;
         }
@@ -973,7 +949,9 @@ int cl_io_loop(const struct lu_env *env, struct cl_io *io)
                 }
                 cl_io_iter_fini(env, io);
         } while (result == 0 && io->ci_continue);
-        RETURN(result < 0 ? result : 0);
+       if (result == 0)
+               result = io->ci_result;
+       RETURN(result < 0 ? result : 0);
 }
 EXPORT_SYMBOL(cl_io_loop);
 
@@ -990,13 +968,13 @@ void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
                      struct cl_object *obj,
                      const struct cl_io_operations *ops)
 {
-        struct list_head *linkage = &slice->cis_linkage;
+       struct list_head *linkage = &slice->cis_linkage;
 
         LASSERT((linkage->prev == NULL && linkage->next == NULL) ||
-                list_empty(linkage));
+               list_empty(linkage));
         ENTRY;
 
-        list_add_tail(linkage, &io->ci_layers);
+       list_add_tail(linkage, &io->ci_layers);
         slice->cis_io  = io;
         slice->cis_obj = obj;
         slice->cis_iop = ops;
@@ -1010,11 +988,11 @@ EXPORT_SYMBOL(cl_io_slice_add);
  */
 void cl_page_list_init(struct cl_page_list *plist)
 {
-        ENTRY;
-        plist->pl_nr = 0;
-        CFS_INIT_LIST_HEAD(&plist->pl_pages);
-        plist->pl_owner = cfs_current();
-        EXIT;
+       ENTRY;
+       plist->pl_nr = 0;
+       INIT_LIST_HEAD(&plist->pl_pages);
+       plist->pl_owner = current;
+       EXIT;
 }
 EXPORT_SYMBOL(cl_page_list_init);
 
@@ -1023,21 +1001,18 @@ EXPORT_SYMBOL(cl_page_list_init);
  */
 void cl_page_list_add(struct cl_page_list *plist, struct cl_page *page)
 {
-        ENTRY;
-        /* it would be better to check that page is owned by "current" io, but
-         * it is not passed here. */
-        LASSERT(page->cp_owner != NULL);
-        LINVRNT(plist->pl_owner == cfs_current());
-
-        lockdep_off();
-        mutex_lock(&page->cp_mutex);
-        lockdep_on();
-        LASSERT(list_empty(&page->cp_batch));
-        list_add_tail(&page->cp_batch, &plist->pl_pages);
-        ++plist->pl_nr;
-        page->cp_queue_ref = lu_ref_add(&page->cp_reference, "queue", plist);
-        cl_page_get(page);
-        EXIT;
+       ENTRY;
+       /* it would be better to check that page is owned by "current" io, but
+        * it is not passed here. */
+       LASSERT(page->cp_owner != NULL);
+       LINVRNT(plist->pl_owner == current);
+
+       LASSERT(list_empty(&page->cp_batch));
+       list_add_tail(&page->cp_batch, &plist->pl_pages);
+       ++plist->pl_nr;
+       lu_ref_add_at(&page->cp_reference, &page->cp_queue_ref, "queue", plist);
+       cl_page_get(page);
+       EXIT;
 }
 EXPORT_SYMBOL(cl_page_list_add);
 
@@ -1045,20 +1020,18 @@ EXPORT_SYMBOL(cl_page_list_add);
  * Removes a page from a page list.
  */
 void cl_page_list_del(const struct lu_env *env,
-                      struct cl_page_list *plist, struct cl_page *page)
+                     struct cl_page_list *plist, struct cl_page *page)
 {
-        LASSERT(plist->pl_nr > 0);
-        LINVRNT(plist->pl_owner == cfs_current());
+       LASSERT(plist->pl_nr > 0);
+       LASSERT(cl_page_is_vmlocked(env, page));
+       LINVRNT(plist->pl_owner == current);
 
-        ENTRY;
-        list_del_init(&page->cp_batch);
-        lockdep_off();
-        mutex_unlock(&page->cp_mutex);
-        lockdep_on();
-        --plist->pl_nr;
-        lu_ref_del_at(&page->cp_reference, page->cp_queue_ref, "queue", plist);
-        cl_page_put(env, page);
-        EXIT;
+       ENTRY;
+       list_del_init(&page->cp_batch);
+       --plist->pl_nr;
+       lu_ref_del_at(&page->cp_reference, &page->cp_queue_ref, "queue", plist);
+       cl_page_put(env, page);
+       EXIT;
 }
 EXPORT_SYMBOL(cl_page_list_del);
 
@@ -1066,37 +1039,57 @@ EXPORT_SYMBOL(cl_page_list_del);
  * Moves a page from one page list to another.
  */
 void cl_page_list_move(struct cl_page_list *dst, struct cl_page_list *src,
-                       struct cl_page *page)
+                      struct cl_page *page)
 {
-        LASSERT(src->pl_nr > 0);
-        LINVRNT(dst->pl_owner == cfs_current());
-        LINVRNT(src->pl_owner == cfs_current());
+       LASSERT(src->pl_nr > 0);
+       LINVRNT(dst->pl_owner == current);
+       LINVRNT(src->pl_owner == current);
 
-        ENTRY;
-        list_move_tail(&page->cp_batch, &dst->pl_pages);
-        --src->pl_nr;
-        ++dst->pl_nr;
-        lu_ref_set_at(&page->cp_reference,
-                      page->cp_queue_ref, "queue", src, dst);
-        EXIT;
+       ENTRY;
+       list_move_tail(&page->cp_batch, &dst->pl_pages);
+       --src->pl_nr;
+       ++dst->pl_nr;
+       lu_ref_set_at(&page->cp_reference, &page->cp_queue_ref, "queue",
+                     src, dst);
+       EXIT;
 }
 EXPORT_SYMBOL(cl_page_list_move);
 
 /**
+ * Moves a page from one page list to the head of another list.
+ */
+void cl_page_list_move_head(struct cl_page_list *dst, struct cl_page_list *src,
+                           struct cl_page *page)
+{
+       LASSERT(src->pl_nr > 0);
+       LINVRNT(dst->pl_owner == current);
+       LINVRNT(src->pl_owner == current);
+
+       ENTRY;
+       list_move(&page->cp_batch, &dst->pl_pages);
+       --src->pl_nr;
+       ++dst->pl_nr;
+       lu_ref_set_at(&page->cp_reference, &page->cp_queue_ref, "queue",
+                       src, dst);
+       EXIT;
+}
+EXPORT_SYMBOL(cl_page_list_move_head);
+
+/**
  * splice the cl_page_list, just as list head does
  */
 void cl_page_list_splice(struct cl_page_list *list, struct cl_page_list *head)
 {
-        struct cl_page *page;
-        struct cl_page *tmp;
+       struct cl_page *page;
+       struct cl_page *tmp;
 
-        LINVRNT(list->pl_owner == cfs_current());
-        LINVRNT(head->pl_owner == cfs_current());
+       LINVRNT(list->pl_owner == current);
+       LINVRNT(head->pl_owner == current);
 
-        ENTRY;
-        cl_page_list_for_each_safe(page, tmp, list)
-                cl_page_list_move(head, list, page);
-        EXIT;
+       ENTRY;
+       cl_page_list_for_each_safe(page, tmp, list)
+               cl_page_list_move(head, list, page);
+       EXIT;
 }
 EXPORT_SYMBOL(cl_page_list_splice);
 
@@ -1107,35 +1100,33 @@ void cl_page_disown0(const struct lu_env *env,
  * Disowns pages in a queue.
  */
 void cl_page_list_disown(const struct lu_env *env,
-                         struct cl_io *io, struct cl_page_list *plist)
-{
-        struct cl_page *page;
-        struct cl_page *temp;
-
-        LINVRNT(plist->pl_owner == cfs_current());
-
-        ENTRY;
-        cl_page_list_for_each_safe(page, temp, plist) {
-                LASSERT(plist->pl_nr > 0);
-
-                list_del_init(&page->cp_batch);
-                lockdep_off();
-                mutex_unlock(&page->cp_mutex);
-                lockdep_on();
-                --plist->pl_nr;
-                /*
-                 * cl_page_disown0 rather than usual cl_page_disown() is used,
-                 * because pages are possibly in CPS_FREEING state already due
-                 * to the call to cl_page_list_discard().
-                 */
-                /*
-                 * XXX cl_page_disown0() will fail if page is not locked.
-                 */
-                cl_page_disown0(env, io, page);
-                lu_ref_del(&page->cp_reference, "queue", plist);
-                cl_page_put(env, page);
-        }
-        EXIT;
+                        struct cl_io *io, struct cl_page_list *plist)
+{
+       struct cl_page *page;
+       struct cl_page *temp;
+
+       LINVRNT(plist->pl_owner == current);
+
+       ENTRY;
+       cl_page_list_for_each_safe(page, temp, plist) {
+               LASSERT(plist->pl_nr > 0);
+
+               list_del_init(&page->cp_batch);
+               --plist->pl_nr;
+               /*
+                * cl_page_disown0 rather than usual cl_page_disown() is used,
+                * because pages are possibly in CPS_FREEING state already due
+                * to the call to cl_page_list_discard().
+                */
+               /*
+                * XXX cl_page_disown0() will fail if page is not locked.
+                */
+               cl_page_disown0(env, io, page);
+               lu_ref_del_at(&page->cp_reference, &page->cp_queue_ref, "queue",
+                             plist);
+               cl_page_put(env, page);
+       }
+       EXIT;
 }
 EXPORT_SYMBOL(cl_page_list_disown);
 
@@ -1144,16 +1135,16 @@ EXPORT_SYMBOL(cl_page_list_disown);
  */
 void cl_page_list_fini(const struct lu_env *env, struct cl_page_list *plist)
 {
-        struct cl_page *page;
-        struct cl_page *temp;
+       struct cl_page *page;
+       struct cl_page *temp;
 
-        LINVRNT(plist->pl_owner == cfs_current());
+       LINVRNT(plist->pl_owner == current);
 
-        ENTRY;
-        cl_page_list_for_each_safe(page, temp, plist)
-                cl_page_list_del(env, plist, page);
-        LASSERT(plist->pl_nr == 0);
-        EXIT;
+       ENTRY;
+       cl_page_list_for_each_safe(page, temp, plist)
+               cl_page_list_del(env, plist, page);
+       LASSERT(plist->pl_nr == 0);
+       EXIT;
 }
 EXPORT_SYMBOL(cl_page_list_fini);
 
@@ -1161,26 +1152,23 @@ EXPORT_SYMBOL(cl_page_list_fini);
  * Owns all pages in a queue.
  */
 int cl_page_list_own(const struct lu_env *env,
-                     struct cl_io *io, struct cl_page_list *plist)
+                    struct cl_io *io, struct cl_page_list *plist)
 {
-        struct cl_page *page;
-        struct cl_page *temp;
-        pgoff_t index = 0;
-        int result;
+       struct cl_page *page;
+       struct cl_page *temp;
+       int result;
 
-        LINVRNT(plist->pl_owner == cfs_current());
+       LINVRNT(plist->pl_owner == current);
 
-        ENTRY;
-        result = 0;
-        cl_page_list_for_each_safe(page, temp, plist) {
-                LASSERT(index <= page->cp_index);
-                index = page->cp_index;
-                if (cl_page_own(env, io, page) == 0)
-                        result = result ?: page->cp_error;
-                else
-                        cl_page_list_del(env, plist, page);
-        }
-        RETURN(result);
+       ENTRY;
+       result = 0;
+       cl_page_list_for_each_safe(page, temp, plist) {
+               if (cl_page_own(env, io, page) == 0)
+                       result = result ?: page->cp_error;
+               else
+                       cl_page_list_del(env, plist, page);
+       }
+       RETURN(result);
 }
 EXPORT_SYMBOL(cl_page_list_own);
 
@@ -1188,14 +1176,14 @@ EXPORT_SYMBOL(cl_page_list_own);
  * Assumes all pages in a queue.
  */
 void cl_page_list_assume(const struct lu_env *env,
-                         struct cl_io *io, struct cl_page_list *plist)
+                        struct cl_io *io, struct cl_page_list *plist)
 {
-        struct cl_page *page;
+       struct cl_page *page;
 
-        LINVRNT(plist->pl_owner == cfs_current());
+       LINVRNT(plist->pl_owner == current);
 
-        cl_page_list_for_each(page, plist)
-                cl_page_assume(env, io, page);
+       cl_page_list_for_each(page, plist)
+               cl_page_assume(env, io, page);
 }
 EXPORT_SYMBOL(cl_page_list_assume);
 
@@ -1203,40 +1191,19 @@ EXPORT_SYMBOL(cl_page_list_assume);
  * Discards all pages in a queue.
  */
 void cl_page_list_discard(const struct lu_env *env, struct cl_io *io,
-                          struct cl_page_list *plist)
+                         struct cl_page_list *plist)
 {
-        struct cl_page *page;
+       struct cl_page *page;
 
-        LINVRNT(plist->pl_owner == cfs_current());
-        ENTRY;
-        cl_page_list_for_each(page, plist)
-                cl_page_discard(env, io, page);
-        EXIT;
+       LINVRNT(plist->pl_owner == current);
+       ENTRY;
+       cl_page_list_for_each(page, plist)
+               cl_page_discard(env, io, page);
+       EXIT;
 }
 EXPORT_SYMBOL(cl_page_list_discard);
 
 /**
- * Unmaps all pages in a queue from user virtual memory.
- */
-int cl_page_list_unmap(const struct lu_env *env, struct cl_io *io,
-                        struct cl_page_list *plist)
-{
-        struct cl_page *page;
-        int result;
-
-        LINVRNT(plist->pl_owner == cfs_current());
-        ENTRY;
-        result = 0;
-        cl_page_list_for_each(page, plist) {
-                result = cl_page_unmap(env, io, page);
-                if (result != 0)
-                        break;
-        }
-        RETURN(result);
-}
-EXPORT_SYMBOL(cl_page_list_unmap);
-
-/**
  * Initialize dual page queue.
  */
 void cl_2queue_init(struct cl_2queue *queue)
@@ -1323,7 +1290,7 @@ EXPORT_SYMBOL(cl_2queue_init_page);
 /**
  * Returns top-level io.
  *
- * \see cl_object_top(), cl_page_top().
+ * \see cl_object_top()
  */
 struct cl_io *cl_io_top(struct cl_io *io)
 {
@@ -1356,7 +1323,7 @@ void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice,
                       const struct cl_req_operations *ops)
 {
         ENTRY;
-        list_add_tail(&slice->crs_linkage, &req->crq_layers);
+       list_add_tail(&slice->crs_linkage, &req->crq_layers);
         slice->crs_dev = dev;
         slice->crs_ops = ops;
         slice->crs_req = req;
@@ -1368,21 +1335,21 @@ static void cl_req_free(const struct lu_env *env, struct cl_req *req)
 {
         unsigned i;
 
-        LASSERT(list_empty(&req->crq_pages));
+       LASSERT(list_empty(&req->crq_pages));
         LASSERT(req->crq_nrpages == 0);
-        LINVRNT(list_empty(&req->crq_layers));
+       LINVRNT(list_empty(&req->crq_layers));
         LINVRNT(equi(req->crq_nrobjs > 0, req->crq_o != NULL));
         ENTRY;
 
         if (req->crq_o != NULL) {
                 for (i = 0; i < req->crq_nrobjs; ++i) {
                         struct cl_object *obj = req->crq_o[i].ro_obj;
-                        if (obj != NULL) {
-                                lu_object_ref_del_at(&obj->co_lu,
-                                                     req->crq_o[i].ro_obj_ref,
-                                                     "cl_req", req);
-                                cl_object_put(env, obj);
-                        }
+                       if (obj != NULL) {
+                               lu_object_ref_del_at(&obj->co_lu,
+                                                    &req->crq_o[i].ro_obj_ref,
+                                                    "cl_req", req);
+                               cl_object_put(env, obj);
+                       }
                 }
                 OBD_FREE(req->crq_o, req->crq_nrobjs * sizeof req->crq_o[0]);
         }
@@ -1393,26 +1360,22 @@ static void cl_req_free(const struct lu_env *env, struct cl_req *req)
 static int cl_req_init(const struct lu_env *env, struct cl_req *req,
                        struct cl_page *page)
 {
-        struct cl_device     *dev;
-        struct cl_page_slice *slice;
-        int result;
+       struct cl_device     *dev;
+       struct cl_page_slice *slice;
+       int result;
 
-        ENTRY;
-        result = 0;
-        page = cl_page_top(page);
-        do {
-                list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
-                        dev = lu2cl_dev(slice->cpl_obj->co_lu.lo_dev);
-                        if (dev->cd_ops->cdo_req_init != NULL) {
-                                result = dev->cd_ops->cdo_req_init(env,
-                                                                   dev, req);
-                                if (result != 0)
-                                        break;
-                        }
-                }
-                page = page->cp_child;
-        } while (page != NULL && result == 0);
-        RETURN(result);
+       ENTRY;
+       result = 0;
+       list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
+               dev = lu2cl_dev(slice->cpl_obj->co_lu.lo_dev);
+               if (dev->cd_ops->cdo_req_init != NULL) {
+                       result = dev->cd_ops->cdo_req_init(env,
+                                       dev, req);
+                       if (result != 0)
+                               break;
+               }
+       }
+       RETURN(result);
 }
 
 /**
@@ -1427,10 +1390,10 @@ void cl_req_completion(const struct lu_env *env, struct cl_req *req, int rc)
         /*
          * for the lack of list_for_each_entry_reverse_safe()...
          */
-        while (!list_empty(&req->crq_layers)) {
-                slice = list_entry(req->crq_layers.prev,
-                                   struct cl_req_slice, crs_linkage);
-                list_del_init(&slice->crs_linkage);
+       while (!list_empty(&req->crq_layers)) {
+               slice = list_entry(req->crq_layers.prev,
+                                  struct cl_req_slice, crs_linkage);
+               list_del_init(&slice->crs_linkage);
                 if (slice->crs_ops->cro_completion != NULL)
                         slice->crs_ops->cro_completion(env, slice, rc);
         }
@@ -1454,12 +1417,13 @@ struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page,
         if (req != NULL) {
                 int result;
 
+               req->crq_type = crt;
+               INIT_LIST_HEAD(&req->crq_pages);
+               INIT_LIST_HEAD(&req->crq_layers);
+
                 OBD_ALLOC(req->crq_o, nr_objects * sizeof req->crq_o[0]);
                 if (req->crq_o != NULL) {
                         req->crq_nrobjs = nr_objects;
-                        req->crq_type = crt;
-                        CFS_INIT_LIST_HEAD(&req->crq_pages);
-                        CFS_INIT_LIST_HEAD(&req->crq_layers);
                         result = cl_req_init(env, req, page);
                 } else
                         result = -ENOMEM;
@@ -1479,18 +1443,19 @@ EXPORT_SYMBOL(cl_req_alloc);
 void cl_req_page_add(const struct lu_env *env,
                      struct cl_req *req, struct cl_page *page)
 {
-        struct cl_object  *obj;
-        struct cl_req_obj *rqo;
-        int i;
+       struct cl_object  *obj;
+       struct cl_req_obj *rqo;
+       int i;
 
-        ENTRY;
-        page = cl_page_top(page);
+       ENTRY;
 
-        LINVRNT(cl_page_is_vmlocked(env, page));
-        LASSERT(list_empty(&page->cp_flight));
+       LASSERT(list_empty(&page->cp_flight));
         LASSERT(page->cp_req == NULL);
 
-        list_add_tail(&page->cp_flight, &req->crq_pages);
+        CL_PAGE_DEBUG(D_PAGE, env, page, "req %p, %d, %u\n",
+                      req, req->crq_type, req->crq_nrpages);
+
+       list_add_tail(&page->cp_flight, &req->crq_pages);
         ++req->crq_nrpages;
         page->cp_req = req;
         obj = cl_object_top(page->cp_obj);
@@ -1498,13 +1463,13 @@ void cl_req_page_add(const struct lu_env *env,
                 if (rqo->ro_obj == NULL) {
                         rqo->ro_obj = obj;
                         cl_object_get(obj);
-                        rqo->ro_obj_ref = lu_object_ref_add(&obj->co_lu,
-                                                            "cl_req", req);
-                        break;
-                }
-        }
-        LASSERT(i < req->crq_nrobjs);
-        EXIT;
+                       lu_object_ref_add_at(&obj->co_lu, &rqo->ro_obj_ref,
+                                            "cl_req", req);
+                       break;
+               }
+       }
+       LASSERT(i < req->crq_nrobjs);
+       EXIT;
 }
 EXPORT_SYMBOL(cl_req_page_add);
 
@@ -1513,19 +1478,17 @@ EXPORT_SYMBOL(cl_req_page_add);
  */
 void cl_req_page_done(const struct lu_env *env, struct cl_page *page)
 {
-        struct cl_req *req = page->cp_req;
+       struct cl_req *req = page->cp_req;
 
-        ENTRY;
-        page = cl_page_top(page);
+       ENTRY;
 
-        LINVRNT(cl_page_is_vmlocked(env, page));
-        LASSERT(!list_empty(&page->cp_flight));
-        LASSERT(req->crq_nrpages > 0);
+       LASSERT(!list_empty(&page->cp_flight));
+       LASSERT(req->crq_nrpages > 0);
 
-        list_del_init(&page->cp_flight);
-        --req->crq_nrpages;
-        page->cp_req = NULL;
-        EXIT;
+       list_del_init(&page->cp_flight);
+       --req->crq_nrpages;
+       page->cp_req = NULL;
+       EXIT;
 }
 EXPORT_SYMBOL(cl_req_page_done);
 
@@ -1548,7 +1511,7 @@ int cl_req_prep(const struct lu_env *env, struct cl_req *req)
                 LASSERT(req->crq_o[i].ro_obj != NULL);
 
         result = 0;
-        list_for_each_entry(slice, &req->crq_layers, crs_linkage) {
+       list_for_each_entry(slice, &req->crq_layers, crs_linkage) {
                 if (slice->crs_ops->cro_prep != NULL) {
                         result = slice->crs_ops->cro_prep(env, slice);
                         if (result != 0)
@@ -1571,14 +1534,14 @@ void cl_req_attr_set(const struct lu_env *env, struct cl_req *req,
         struct cl_page            *page;
         int i;
 
-        LASSERT(!list_empty(&req->crq_pages));
+       LASSERT(!list_empty(&req->crq_pages));
         ENTRY;
 
         /* Take any page to use as a model. */
-        page = list_entry(req->crq_pages.next, struct cl_page, cp_flight);
+       page = list_entry(req->crq_pages.next, struct cl_page, cp_flight);
 
         for (i = 0; i < req->crq_nrobjs; ++i) {
-                list_for_each_entry(slice, &req->crq_layers, crs_linkage) {
+               list_for_each_entry(slice, &req->crq_layers, crs_linkage) {
                         const struct cl_page_slice *scan;
                         const struct cl_object     *obj;
 
@@ -1608,11 +1571,12 @@ EXPORT_SYMBOL(cl_req_attr_set);
  */
 void cl_sync_io_init(struct cl_sync_io *anchor, int nrpages)
 {
-        ENTRY;
-        cfs_waitq_init(&anchor->csi_waitq);
-        atomic_set(&anchor->csi_sync_nr, nrpages);
-        anchor->csi_sync_rc  = 0;
-        EXIT;
+       ENTRY;
+       init_waitqueue_head(&anchor->csi_waitq);
+       atomic_set(&anchor->csi_sync_nr, nrpages);
+       atomic_set(&anchor->csi_barrier, nrpages > 0);
+       anchor->csi_sync_rc = 0;
+       EXIT;
 }
 EXPORT_SYMBOL(cl_sync_io_init);
 
@@ -1632,33 +1596,34 @@ int cl_sync_io_wait(const struct lu_env *env, struct cl_io *io,
         LASSERT(timeout >= 0);
 
         rc = l_wait_event(anchor->csi_waitq,
-                          atomic_read(&anchor->csi_sync_nr) == 0,
+                         atomic_read(&anchor->csi_sync_nr) == 0,
                           &lwi);
         if (rc < 0) {
-                int rc2;
-
                 CERROR("SYNC IO failed with error: %d, try to cancel "
-                       "the remaining page\n", rc);
-
-                rc2 = cl_io_cancel(env, io, queue);
-                if (rc2 < 0) {
-                        lwi = (struct l_wait_info) { 0 };
-                        /* Too bad, some pages are still in IO. */
-                        CERROR("Failed to cancel transfer error: %d, mostly "
-                               "because of they are still being transferred, "
-                               "waiting for %i pages\n",
-                               rc2, atomic_read(&anchor->csi_sync_nr));
-                        (void)l_wait_event(anchor->csi_waitq,
-                                     atomic_read(&anchor->csi_sync_nr) == 0,
-                                     &lwi);
-                }
+                       "%d remaining pages\n",
+                      rc, atomic_read(&anchor->csi_sync_nr));
+
+                (void)cl_io_cancel(env, io, queue);
+
+                lwi = (struct l_wait_info) { 0 };
+                (void)l_wait_event(anchor->csi_waitq,
+                                  atomic_read(&anchor->csi_sync_nr) == 0,
+                                   &lwi);
         } else {
                 rc = anchor->csi_sync_rc;
         }
-        LASSERT(atomic_read(&anchor->csi_sync_nr) == 0);
+       LASSERT(atomic_read(&anchor->csi_sync_nr) == 0);
         cl_page_list_assume(env, io, queue);
-        POISON(anchor, 0x5a, sizeof *anchor);
-        RETURN(rc);
+
+       /* wait until cl_sync_io_note() has done wakeup */
+       while (unlikely(atomic_read(&anchor->csi_barrier) != 0)) {
+#ifdef __KERNEL__
+               cpu_relax();
+#endif
+       }
+
+       POISON(anchor, 0x5a, sizeof *anchor);
+       RETURN(rc);
 }
 EXPORT_SYMBOL(cl_sync_io_wait);
 
@@ -1675,8 +1640,12 @@ void cl_sync_io_note(struct cl_sync_io *anchor, int ioret)
          * ->{prepare,commit}_write(). Completion is used to signal the end of
          * IO.
          */
-        if (atomic_dec_and_test(&anchor->csi_sync_nr))
-                cfs_waitq_broadcast(&anchor->csi_waitq);
-        EXIT;
+       LASSERT(atomic_read(&anchor->csi_sync_nr) > 0);
+       if (atomic_dec_and_test(&anchor->csi_sync_nr)) {
+               wake_up_all(&anchor->csi_waitq);
+               /* it's safe to nuke or reuse anchor now */
+               atomic_set(&anchor->csi_barrier, 0);
+       }
+       EXIT;
 }
 EXPORT_SYMBOL(cl_sync_io_note);