Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / drivers / staging / lustre / lustre / lov / lov_object.c
diff --git a/kernel/drivers/staging/lustre/lustre/lov/lov_object.c b/kernel/drivers/staging/lustre/lustre/lov/lov_object.c
new file mode 100644 (file)
index 0000000..a22342f
--- /dev/null
@@ -0,0 +1,1001 @@
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * 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.
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Use is subject to license terms.
+ *
+ * Copyright (c) 2011, 2012, Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ *
+ * Implementation of cl_object for LOV layer.
+ *
+ *   Author: Nikita Danilov <nikita.danilov@sun.com>
+ *   Author: Jinshan Xiong <jinshan.xiong@whamcloud.com>
+ */
+
+#define DEBUG_SUBSYSTEM S_LOV
+
+#include "lov_cl_internal.h"
+#include "../include/lclient.h"
+
+/** \addtogroup lov
+ *  @{
+ */
+
+/*****************************************************************************
+ *
+ * Layout operations.
+ *
+ */
+
+struct lov_layout_operations {
+       int (*llo_init)(const struct lu_env *env, struct lov_device *dev,
+                       struct lov_object *lov,
+                       const struct cl_object_conf *conf,
+                       union lov_layout_state *state);
+       int (*llo_delete)(const struct lu_env *env, struct lov_object *lov,
+                          union lov_layout_state *state);
+       void (*llo_fini)(const struct lu_env *env, struct lov_object *lov,
+                        union lov_layout_state *state);
+       void (*llo_install)(const struct lu_env *env, struct lov_object *lov,
+                           union lov_layout_state *state);
+       int  (*llo_print)(const struct lu_env *env, void *cookie,
+                         lu_printer_t p, const struct lu_object *o);
+       int  (*llo_page_init)(const struct lu_env *env, struct cl_object *obj,
+                               struct cl_page *page, struct page *vmpage);
+       int  (*llo_lock_init)(const struct lu_env *env,
+                             struct cl_object *obj, struct cl_lock *lock,
+                             const struct cl_io *io);
+       int  (*llo_io_init)(const struct lu_env *env,
+                           struct cl_object *obj, struct cl_io *io);
+       int  (*llo_getattr)(const struct lu_env *env, struct cl_object *obj,
+                           struct cl_attr *attr);
+};
+
+static int lov_layout_wait(const struct lu_env *env, struct lov_object *lov);
+
+/*****************************************************************************
+ *
+ * Lov object layout operations.
+ *
+ */
+
+static void lov_install_empty(const struct lu_env *env,
+                             struct lov_object *lov,
+                             union  lov_layout_state *state)
+{
+       /*
+        * File without objects.
+        */
+}
+
+static int lov_init_empty(const struct lu_env *env,
+                         struct lov_device *dev, struct lov_object *lov,
+                         const struct cl_object_conf *conf,
+                         union  lov_layout_state *state)
+{
+       return 0;
+}
+
+static void lov_install_raid0(const struct lu_env *env,
+                             struct lov_object *lov,
+                             union  lov_layout_state *state)
+{
+}
+
+static struct cl_object *lov_sub_find(const struct lu_env *env,
+                                     struct cl_device *dev,
+                                     const struct lu_fid *fid,
+                                     const struct cl_object_conf *conf)
+{
+       struct lu_object *o;
+
+       o = lu_object_find_at(env, cl2lu_dev(dev), fid, &conf->coc_lu);
+       LASSERT(ergo(!IS_ERR(o), o->lo_dev->ld_type == &lovsub_device_type));
+       return lu2cl(o);
+}
+
+static int lov_init_sub(const struct lu_env *env, struct lov_object *lov,
+                       struct cl_object *stripe, struct lov_layout_raid0 *r0,
+                       int idx)
+{
+       struct cl_object_header *hdr;
+       struct cl_object_header *subhdr;
+       struct cl_object_header *parent;
+       struct lov_oinfo        *oinfo;
+       int result;
+
+       if (OBD_FAIL_CHECK(OBD_FAIL_LOV_INIT)) {
+               /* For sanity:test_206.
+                * Do not leave the object in cache to avoid accessing
+                * freed memory. This is because osc_object is referring to
+                * lov_oinfo of lsm_stripe_data which will be freed due to
+                * this failure. */
+               cl_object_kill(env, stripe);
+               cl_object_put(env, stripe);
+               return -EIO;
+       }
+
+       hdr    = cl_object_header(lov2cl(lov));
+       subhdr = cl_object_header(stripe);
+
+       oinfo = lov->lo_lsm->lsm_oinfo[idx];
+       CDEBUG(D_INODE, DFID"@%p[%d] -> "DFID"@%p: ostid: "DOSTID
+              " idx: %d gen: %d\n",
+              PFID(&subhdr->coh_lu.loh_fid), subhdr, idx,
+              PFID(&hdr->coh_lu.loh_fid), hdr, POSTID(&oinfo->loi_oi),
+              oinfo->loi_ost_idx, oinfo->loi_ost_gen);
+
+       /* reuse ->coh_attr_guard to protect coh_parent change */
+       spin_lock(&subhdr->coh_attr_guard);
+       parent = subhdr->coh_parent;
+       if (parent == NULL) {
+               subhdr->coh_parent = hdr;
+               spin_unlock(&subhdr->coh_attr_guard);
+               subhdr->coh_nesting = hdr->coh_nesting + 1;
+               lu_object_ref_add(&stripe->co_lu, "lov-parent", lov);
+               r0->lo_sub[idx] = cl2lovsub(stripe);
+               r0->lo_sub[idx]->lso_super = lov;
+               r0->lo_sub[idx]->lso_index = idx;
+               result = 0;
+       } else {
+               struct lu_object  *old_obj;
+               struct lov_object *old_lov;
+               unsigned int mask = D_INODE;
+
+               spin_unlock(&subhdr->coh_attr_guard);
+               old_obj = lu_object_locate(&parent->coh_lu, &lov_device_type);
+               LASSERT(old_obj != NULL);
+               old_lov = cl2lov(lu2cl(old_obj));
+               if (old_lov->lo_layout_invalid) {
+                       /* the object's layout has already changed but isn't
+                        * refreshed */
+                       lu_object_unhash(env, &stripe->co_lu);
+                       result = -EAGAIN;
+               } else {
+                       mask = D_ERROR;
+                       result = -EIO;
+               }
+
+               LU_OBJECT_DEBUG(mask, env, &stripe->co_lu,
+                               "stripe %d is already owned.\n", idx);
+               LU_OBJECT_DEBUG(mask, env, old_obj, "owned.\n");
+               LU_OBJECT_HEADER(mask, env, lov2lu(lov), "try to own.\n");
+               cl_object_put(env, stripe);
+       }
+       return result;
+}
+
+static int lov_init_raid0(const struct lu_env *env,
+                         struct lov_device *dev, struct lov_object *lov,
+                         const struct cl_object_conf *conf,
+                         union  lov_layout_state *state)
+{
+       int result;
+       int i;
+
+       struct cl_object        *stripe;
+       struct lov_thread_info  *lti     = lov_env_info(env);
+       struct cl_object_conf   *subconf = &lti->lti_stripe_conf;
+       struct lov_stripe_md    *lsm     = conf->u.coc_md->lsm;
+       struct lu_fid      *ofid    = &lti->lti_fid;
+       struct lov_layout_raid0 *r0      = &state->raid0;
+
+       if (lsm->lsm_magic != LOV_MAGIC_V1 && lsm->lsm_magic != LOV_MAGIC_V3) {
+               dump_lsm(D_ERROR, lsm);
+               LASSERTF(0, "magic mismatch, expected %d/%d, actual %d.\n",
+                        LOV_MAGIC_V1, LOV_MAGIC_V3, lsm->lsm_magic);
+       }
+
+       LASSERT(lov->lo_lsm == NULL);
+       lov->lo_lsm = lsm_addref(lsm);
+       r0->lo_nr  = lsm->lsm_stripe_count;
+       LASSERT(r0->lo_nr <= lov_targets_nr(dev));
+
+       OBD_ALLOC_LARGE(r0->lo_sub, r0->lo_nr * sizeof(r0->lo_sub[0]));
+       if (r0->lo_sub != NULL) {
+               result = 0;
+               subconf->coc_inode = conf->coc_inode;
+               spin_lock_init(&r0->lo_sub_lock);
+               /*
+                * Create stripe cl_objects.
+                */
+               for (i = 0; i < r0->lo_nr && result == 0; ++i) {
+                       struct cl_device *subdev;
+                       struct lov_oinfo *oinfo = lsm->lsm_oinfo[i];
+                       int ost_idx = oinfo->loi_ost_idx;
+
+                       if (lov_oinfo_is_dummy(oinfo))
+                               continue;
+
+                       result = ostid_to_fid(ofid, &oinfo->loi_oi,
+                                             oinfo->loi_ost_idx);
+                       if (result != 0)
+                               goto out;
+
+                       subdev = lovsub2cl_dev(dev->ld_target[ost_idx]);
+                       subconf->u.coc_oinfo = oinfo;
+                       LASSERTF(subdev != NULL, "not init ost %d\n", ost_idx);
+                       /* In the function below, .hs_keycmp resolves to
+                        * lu_obj_hop_keycmp() */
+                       /* coverity[overrun-buffer-val] */
+                       stripe = lov_sub_find(env, subdev, ofid, subconf);
+                       if (!IS_ERR(stripe)) {
+                               result = lov_init_sub(env, lov, stripe, r0, i);
+                               if (result == -EAGAIN) { /* try again */
+                                       --i;
+                                       result = 0;
+                               }
+                       } else {
+                               result = PTR_ERR(stripe);
+                       }
+               }
+       } else
+               result = -ENOMEM;
+out:
+       return result;
+}
+
+static int lov_init_released(const struct lu_env *env,
+                       struct lov_device *dev, struct lov_object *lov,
+                       const struct cl_object_conf *conf,
+                       union  lov_layout_state *state)
+{
+       struct lov_stripe_md *lsm = conf->u.coc_md->lsm;
+
+       LASSERT(lsm != NULL);
+       LASSERT(lsm_is_released(lsm));
+       LASSERT(lov->lo_lsm == NULL);
+
+       lov->lo_lsm = lsm_addref(lsm);
+       return 0;
+}
+
+static int lov_delete_empty(const struct lu_env *env, struct lov_object *lov,
+                           union lov_layout_state *state)
+{
+       LASSERT(lov->lo_type == LLT_EMPTY || lov->lo_type == LLT_RELEASED);
+
+       lov_layout_wait(env, lov);
+
+       cl_object_prune(env, &lov->lo_cl);
+       return 0;
+}
+
+static void lov_subobject_kill(const struct lu_env *env, struct lov_object *lov,
+                              struct lovsub_object *los, int idx)
+{
+       struct cl_object        *sub;
+       struct lov_layout_raid0 *r0;
+       struct lu_site    *site;
+       struct lu_site_bkt_data *bkt;
+       wait_queue_t      *waiter;
+
+       r0  = &lov->u.raid0;
+       LASSERT(r0->lo_sub[idx] == los);
+
+       sub  = lovsub2cl(los);
+       site = sub->co_lu.lo_dev->ld_site;
+       bkt  = lu_site_bkt_from_fid(site, &sub->co_lu.lo_header->loh_fid);
+
+       cl_object_kill(env, sub);
+       /* release a reference to the sub-object and ... */
+       lu_object_ref_del(&sub->co_lu, "lov-parent", lov);
+       cl_object_put(env, sub);
+
+       /* ... wait until it is actually destroyed---sub-object clears its
+        * ->lo_sub[] slot in lovsub_object_fini() */
+       if (r0->lo_sub[idx] == los) {
+               waiter = &lov_env_info(env)->lti_waiter;
+               init_waitqueue_entry(waiter, current);
+               add_wait_queue(&bkt->lsb_marche_funebre, waiter);
+               set_current_state(TASK_UNINTERRUPTIBLE);
+               while (1) {
+                       /* this wait-queue is signaled at the end of
+                        * lu_object_free(). */
+                       set_current_state(TASK_UNINTERRUPTIBLE);
+                       spin_lock(&r0->lo_sub_lock);
+                       if (r0->lo_sub[idx] == los) {
+                               spin_unlock(&r0->lo_sub_lock);
+                               schedule();
+                       } else {
+                               spin_unlock(&r0->lo_sub_lock);
+                               set_current_state(TASK_RUNNING);
+                               break;
+                       }
+               }
+               remove_wait_queue(&bkt->lsb_marche_funebre, waiter);
+       }
+       LASSERT(r0->lo_sub[idx] == NULL);
+}
+
+static int lov_delete_raid0(const struct lu_env *env, struct lov_object *lov,
+                           union lov_layout_state *state)
+{
+       struct lov_layout_raid0 *r0 = &state->raid0;
+       struct lov_stripe_md    *lsm = lov->lo_lsm;
+       int i;
+
+       dump_lsm(D_INODE, lsm);
+
+       lov_layout_wait(env, lov);
+       if (r0->lo_sub != NULL) {
+               for (i = 0; i < r0->lo_nr; ++i) {
+                       struct lovsub_object *los = r0->lo_sub[i];
+
+                       if (los != NULL) {
+                               cl_locks_prune(env, &los->lso_cl, 1);
+                               /*
+                                * If top-level object is to be evicted from
+                                * the cache, so are its sub-objects.
+                                */
+                               lov_subobject_kill(env, lov, los, i);
+                       }
+               }
+       }
+       cl_object_prune(env, &lov->lo_cl);
+       return 0;
+}
+
+static void lov_fini_empty(const struct lu_env *env, struct lov_object *lov,
+                          union lov_layout_state *state)
+{
+       LASSERT(lov->lo_type == LLT_EMPTY || lov->lo_type == LLT_RELEASED);
+}
+
+static void lov_fini_raid0(const struct lu_env *env, struct lov_object *lov,
+                          union lov_layout_state *state)
+{
+       struct lov_layout_raid0 *r0 = &state->raid0;
+
+       if (r0->lo_sub != NULL) {
+               OBD_FREE_LARGE(r0->lo_sub, r0->lo_nr * sizeof(r0->lo_sub[0]));
+               r0->lo_sub = NULL;
+       }
+
+       dump_lsm(D_INODE, lov->lo_lsm);
+       lov_free_memmd(&lov->lo_lsm);
+}
+
+static void lov_fini_released(const struct lu_env *env, struct lov_object *lov,
+                               union lov_layout_state *state)
+{
+       dump_lsm(D_INODE, lov->lo_lsm);
+       lov_free_memmd(&lov->lo_lsm);
+}
+
+static int lov_print_empty(const struct lu_env *env, void *cookie,
+                          lu_printer_t p, const struct lu_object *o)
+{
+       (*p)(env, cookie, "empty %d\n", lu2lov(o)->lo_layout_invalid);
+       return 0;
+}
+
+static int lov_print_raid0(const struct lu_env *env, void *cookie,
+                          lu_printer_t p, const struct lu_object *o)
+{
+       struct lov_object       *lov = lu2lov(o);
+       struct lov_layout_raid0 *r0  = lov_r0(lov);
+       struct lov_stripe_md    *lsm = lov->lo_lsm;
+       int                      i;
+
+       (*p)(env, cookie, "stripes: %d, %s, lsm{%p 0x%08X %d %u %u}:\n",
+               r0->lo_nr, lov->lo_layout_invalid ? "invalid" : "valid", lsm,
+               lsm->lsm_magic, atomic_read(&lsm->lsm_refc),
+               lsm->lsm_stripe_count, lsm->lsm_layout_gen);
+       for (i = 0; i < r0->lo_nr; ++i) {
+               struct lu_object *sub;
+
+               if (r0->lo_sub[i] != NULL) {
+                       sub = lovsub2lu(r0->lo_sub[i]);
+                       lu_object_print(env, cookie, p, sub);
+               } else {
+                       (*p)(env, cookie, "sub %d absent\n", i);
+               }
+       }
+       return 0;
+}
+
+static int lov_print_released(const struct lu_env *env, void *cookie,
+                               lu_printer_t p, const struct lu_object *o)
+{
+       struct lov_object       *lov = lu2lov(o);
+       struct lov_stripe_md    *lsm = lov->lo_lsm;
+
+       (*p)(env, cookie,
+               "released: %s, lsm{%p 0x%08X %d %u %u}:\n",
+               lov->lo_layout_invalid ? "invalid" : "valid", lsm,
+               lsm->lsm_magic, atomic_read(&lsm->lsm_refc),
+               lsm->lsm_stripe_count, lsm->lsm_layout_gen);
+       return 0;
+}
+
+/**
+ * Implements cl_object_operations::coo_attr_get() method for an object
+ * without stripes (LLT_EMPTY layout type).
+ *
+ * The only attributes this layer is authoritative in this case is
+ * cl_attr::cat_blocks---it's 0.
+ */
+static int lov_attr_get_empty(const struct lu_env *env, struct cl_object *obj,
+                             struct cl_attr *attr)
+{
+       attr->cat_blocks = 0;
+       return 0;
+}
+
+static int lov_attr_get_raid0(const struct lu_env *env, struct cl_object *obj,
+                             struct cl_attr *attr)
+{
+       struct lov_object       *lov = cl2lov(obj);
+       struct lov_layout_raid0 *r0 = lov_r0(lov);
+       struct cl_attr          *lov_attr = &r0->lo_attr;
+       int                      result = 0;
+
+       /* this is called w/o holding type guard mutex, so it must be inside
+        * an on going IO otherwise lsm may be replaced.
+        * LU-2117: it turns out there exists one exception. For mmaped files,
+        * the lock of those files may be requested in the other file's IO
+        * context, and this function is called in ccc_lock_state(), it will
+        * hit this assertion.
+        * Anyway, it's still okay to call attr_get w/o type guard as layout
+        * can't go if locks exist. */
+       /* LASSERT(atomic_read(&lsm->lsm_refc) > 1); */
+
+       if (!r0->lo_attr_valid) {
+               struct lov_stripe_md    *lsm = lov->lo_lsm;
+               struct ost_lvb    *lvb = &lov_env_info(env)->lti_lvb;
+               __u64               kms = 0;
+
+               memset(lvb, 0, sizeof(*lvb));
+               /* XXX: timestamps can be negative by sanity:test_39m,
+                * how can it be? */
+               lvb->lvb_atime = LLONG_MIN;
+               lvb->lvb_ctime = LLONG_MIN;
+               lvb->lvb_mtime = LLONG_MIN;
+
+               /*
+                * XXX that should be replaced with a loop over sub-objects,
+                * doing cl_object_attr_get() on them. But for now, let's
+                * reuse old lov code.
+                */
+
+               /*
+                * XXX take lsm spin-lock to keep lov_merge_lvb_kms()
+                * happy. It's not needed, because new code uses
+                * ->coh_attr_guard spin-lock to protect consistency of
+                * sub-object attributes.
+                */
+               lov_stripe_lock(lsm);
+               result = lov_merge_lvb_kms(lsm, lvb, &kms);
+               lov_stripe_unlock(lsm);
+               if (result == 0) {
+                       cl_lvb2attr(lov_attr, lvb);
+                       lov_attr->cat_kms = kms;
+                       r0->lo_attr_valid = 1;
+               }
+       }
+       if (result == 0) { /* merge results */
+               attr->cat_blocks = lov_attr->cat_blocks;
+               attr->cat_size = lov_attr->cat_size;
+               attr->cat_kms = lov_attr->cat_kms;
+               if (attr->cat_atime < lov_attr->cat_atime)
+                       attr->cat_atime = lov_attr->cat_atime;
+               if (attr->cat_ctime < lov_attr->cat_ctime)
+                       attr->cat_ctime = lov_attr->cat_ctime;
+               if (attr->cat_mtime < lov_attr->cat_mtime)
+                       attr->cat_mtime = lov_attr->cat_mtime;
+       }
+       return result;
+}
+
+static const struct lov_layout_operations lov_dispatch[] = {
+       [LLT_EMPTY] = {
+               .llo_init      = lov_init_empty,
+               .llo_delete    = lov_delete_empty,
+               .llo_fini      = lov_fini_empty,
+               .llo_install   = lov_install_empty,
+               .llo_print     = lov_print_empty,
+               .llo_page_init = lov_page_init_empty,
+               .llo_lock_init = lov_lock_init_empty,
+               .llo_io_init   = lov_io_init_empty,
+               .llo_getattr   = lov_attr_get_empty
+       },
+       [LLT_RAID0] = {
+               .llo_init      = lov_init_raid0,
+               .llo_delete    = lov_delete_raid0,
+               .llo_fini      = lov_fini_raid0,
+               .llo_install   = lov_install_raid0,
+               .llo_print     = lov_print_raid0,
+               .llo_page_init = lov_page_init_raid0,
+               .llo_lock_init = lov_lock_init_raid0,
+               .llo_io_init   = lov_io_init_raid0,
+               .llo_getattr   = lov_attr_get_raid0
+       },
+       [LLT_RELEASED] = {
+               .llo_init      = lov_init_released,
+               .llo_delete    = lov_delete_empty,
+               .llo_fini      = lov_fini_released,
+               .llo_install   = lov_install_empty,
+               .llo_print     = lov_print_released,
+               .llo_page_init = lov_page_init_empty,
+               .llo_lock_init = lov_lock_init_empty,
+               .llo_io_init   = lov_io_init_released,
+               .llo_getattr   = lov_attr_get_empty
+       }
+};
+
+/**
+ * Performs a double-dispatch based on the layout type of an object.
+ */
+#define LOV_2DISPATCH_NOLOCK(obj, op, ...)                           \
+({                                                                   \
+       struct lov_object                     *__obj = (obj);     \
+       enum lov_layout_type                __llt;                \
+                                                                       \
+       __llt = __obj->lo_type;                                  \
+       LASSERT(0 <= __llt && __llt < ARRAY_SIZE(lov_dispatch));        \
+       lov_dispatch[__llt].op(__VA_ARGS__);                        \
+})
+
+/**
+ * Return lov_layout_type associated with a given lsm
+ */
+static enum lov_layout_type lov_type(struct lov_stripe_md *lsm)
+{
+       if (lsm == NULL)
+               return LLT_EMPTY;
+       if (lsm_is_released(lsm))
+               return LLT_RELEASED;
+       return LLT_RAID0;
+}
+
+static inline void lov_conf_freeze(struct lov_object *lov)
+{
+       if (lov->lo_owner != current)
+               down_read(&lov->lo_type_guard);
+}
+
+static inline void lov_conf_thaw(struct lov_object *lov)
+{
+       if (lov->lo_owner != current)
+               up_read(&lov->lo_type_guard);
+}
+
+#define LOV_2DISPATCH_MAYLOCK(obj, op, lock, ...)                     \
+({                                                                   \
+       struct lov_object                     *__obj = (obj);     \
+       int                                  __lock = !!(lock);      \
+       typeof(lov_dispatch[0].op(__VA_ARGS__)) __result;              \
+                                                                       \
+       if (__lock)                                                  \
+               lov_conf_freeze(__obj);                                 \
+       __result = LOV_2DISPATCH_NOLOCK(obj, op, __VA_ARGS__);    \
+       if (__lock)                                                  \
+               lov_conf_thaw(__obj);                                   \
+       __result;                                                      \
+})
+
+/**
+ * Performs a locked double-dispatch based on the layout type of an object.
+ */
+#define LOV_2DISPATCH(obj, op, ...)                 \
+       LOV_2DISPATCH_MAYLOCK(obj, op, 1, __VA_ARGS__)
+
+#define LOV_2DISPATCH_VOID(obj, op, ...)                               \
+do {                                                               \
+       struct lov_object                     *__obj = (obj);     \
+       enum lov_layout_type                __llt;                \
+                                                                       \
+       lov_conf_freeze(__obj);                                         \
+       __llt = __obj->lo_type;                                  \
+       LASSERT(0 <= __llt && __llt < ARRAY_SIZE(lov_dispatch));        \
+       lov_dispatch[__llt].op(__VA_ARGS__);                        \
+       lov_conf_thaw(__obj);                                           \
+} while (0)
+
+static void lov_conf_lock(struct lov_object *lov)
+{
+       LASSERT(lov->lo_owner != current);
+       down_write(&lov->lo_type_guard);
+       LASSERT(lov->lo_owner == NULL);
+       lov->lo_owner = current;
+}
+
+static void lov_conf_unlock(struct lov_object *lov)
+{
+       lov->lo_owner = NULL;
+       up_write(&lov->lo_type_guard);
+}
+
+static int lov_layout_wait(const struct lu_env *env, struct lov_object *lov)
+{
+       struct l_wait_info lwi = { 0 };
+
+       while (atomic_read(&lov->lo_active_ios) > 0) {
+               CDEBUG(D_INODE, "file:"DFID" wait for active IO, now: %d.\n",
+                       PFID(lu_object_fid(lov2lu(lov))),
+                       atomic_read(&lov->lo_active_ios));
+
+               l_wait_event(lov->lo_waitq,
+                            atomic_read(&lov->lo_active_ios) == 0, &lwi);
+       }
+       return 0;
+}
+
+static int lov_layout_change(const struct lu_env *unused,
+                            struct lov_object *lov,
+                            const struct cl_object_conf *conf)
+{
+       int result;
+       enum lov_layout_type llt = LLT_EMPTY;
+       union lov_layout_state *state = &lov->u;
+       const struct lov_layout_operations *old_ops;
+       const struct lov_layout_operations *new_ops;
+
+       struct cl_object_header *hdr = cl_object_header(&lov->lo_cl);
+       void *cookie;
+       struct lu_env *env;
+       int refcheck;
+
+       LASSERT(0 <= lov->lo_type && lov->lo_type < ARRAY_SIZE(lov_dispatch));
+
+       if (conf->u.coc_md != NULL)
+               llt = lov_type(conf->u.coc_md->lsm);
+       LASSERT(0 <= llt && llt < ARRAY_SIZE(lov_dispatch));
+
+       cookie = cl_env_reenter();
+       env = cl_env_get(&refcheck);
+       if (IS_ERR(env)) {
+               cl_env_reexit(cookie);
+               return PTR_ERR(env);
+       }
+
+       CDEBUG(D_INODE, DFID" from %s to %s\n",
+              PFID(lu_object_fid(lov2lu(lov))),
+              llt2str(lov->lo_type), llt2str(llt));
+
+       old_ops = &lov_dispatch[lov->lo_type];
+       new_ops = &lov_dispatch[llt];
+
+       result = old_ops->llo_delete(env, lov, &lov->u);
+       if (result == 0) {
+               old_ops->llo_fini(env, lov, &lov->u);
+
+               LASSERT(atomic_read(&lov->lo_active_ios) == 0);
+               LASSERT(hdr->coh_tree.rnode == NULL);
+               LASSERT(hdr->coh_pages == 0);
+
+               lov->lo_type = LLT_EMPTY;
+               result = new_ops->llo_init(env,
+                                       lu2lov_dev(lov->lo_cl.co_lu.lo_dev),
+                                       lov, conf, state);
+               if (result == 0) {
+                       new_ops->llo_install(env, lov, state);
+                       lov->lo_type = llt;
+               } else {
+                       new_ops->llo_delete(env, lov, state);
+                       new_ops->llo_fini(env, lov, state);
+                       /* this file becomes an EMPTY file. */
+               }
+       }
+
+       cl_env_put(env, &refcheck);
+       cl_env_reexit(cookie);
+       return result;
+}
+
+/*****************************************************************************
+ *
+ * Lov object operations.
+ *
+ */
+int lov_object_init(const struct lu_env *env, struct lu_object *obj,
+                   const struct lu_object_conf *conf)
+{
+       struct lov_device           *dev   = lu2lov_dev(obj->lo_dev);
+       struct lov_object           *lov   = lu2lov(obj);
+       const struct cl_object_conf  *cconf = lu2cl_conf(conf);
+       union  lov_layout_state      *set   = &lov->u;
+       const struct lov_layout_operations *ops;
+       int result;
+
+       init_rwsem(&lov->lo_type_guard);
+       atomic_set(&lov->lo_active_ios, 0);
+       init_waitqueue_head(&lov->lo_waitq);
+
+       cl_object_page_init(lu2cl(obj), sizeof(struct lov_page));
+
+       /* no locking is necessary, as object is being created */
+       lov->lo_type = lov_type(cconf->u.coc_md->lsm);
+       ops = &lov_dispatch[lov->lo_type];
+       result = ops->llo_init(env, dev, lov, cconf, set);
+       if (result == 0)
+               ops->llo_install(env, lov, set);
+       return result;
+}
+
+static int lov_conf_set(const struct lu_env *env, struct cl_object *obj,
+                       const struct cl_object_conf *conf)
+{
+       struct lov_stripe_md    *lsm = NULL;
+       struct lov_object       *lov = cl2lov(obj);
+       int                      result = 0;
+
+       lov_conf_lock(lov);
+       if (conf->coc_opc == OBJECT_CONF_INVALIDATE) {
+               lov->lo_layout_invalid = true;
+               result = 0;
+               goto out;
+       }
+
+       if (conf->coc_opc == OBJECT_CONF_WAIT) {
+               if (lov->lo_layout_invalid &&
+                   atomic_read(&lov->lo_active_ios) > 0) {
+                       lov_conf_unlock(lov);
+                       result = lov_layout_wait(env, lov);
+                       lov_conf_lock(lov);
+               }
+               goto out;
+       }
+
+       LASSERT(conf->coc_opc == OBJECT_CONF_SET);
+
+       if (conf->u.coc_md != NULL)
+               lsm = conf->u.coc_md->lsm;
+       if ((lsm == NULL && lov->lo_lsm == NULL) ||
+           ((lsm != NULL && lov->lo_lsm != NULL) &&
+            (lov->lo_lsm->lsm_layout_gen == lsm->lsm_layout_gen) &&
+            (lov->lo_lsm->lsm_pattern == lsm->lsm_pattern))) {
+               /* same version of layout */
+               lov->lo_layout_invalid = false;
+               result = 0;
+               goto out;
+       }
+
+       /* will change layout - check if there still exists active IO. */
+       if (atomic_read(&lov->lo_active_ios) > 0) {
+               lov->lo_layout_invalid = true;
+               result = -EBUSY;
+               goto out;
+       }
+
+       lov->lo_layout_invalid = lov_layout_change(env, lov, conf);
+
+out:
+       lov_conf_unlock(lov);
+       CDEBUG(D_INODE, DFID" lo_layout_invalid=%d\n",
+              PFID(lu_object_fid(lov2lu(lov))), lov->lo_layout_invalid);
+       return result;
+}
+
+static void lov_object_delete(const struct lu_env *env, struct lu_object *obj)
+{
+       struct lov_object *lov = lu2lov(obj);
+
+       LOV_2DISPATCH_VOID(lov, llo_delete, env, lov, &lov->u);
+}
+
+static void lov_object_free(const struct lu_env *env, struct lu_object *obj)
+{
+       struct lov_object *lov = lu2lov(obj);
+
+       LOV_2DISPATCH_VOID(lov, llo_fini, env, lov, &lov->u);
+       lu_object_fini(obj);
+       OBD_SLAB_FREE_PTR(lov, lov_object_kmem);
+}
+
+static int lov_object_print(const struct lu_env *env, void *cookie,
+                           lu_printer_t p, const struct lu_object *o)
+{
+       return LOV_2DISPATCH_NOLOCK(lu2lov(o), llo_print, env, cookie, p, o);
+}
+
+int lov_page_init(const struct lu_env *env, struct cl_object *obj,
+               struct cl_page *page, struct page *vmpage)
+{
+       return LOV_2DISPATCH_NOLOCK(cl2lov(obj),
+                                   llo_page_init, env, obj, page, vmpage);
+}
+
+/**
+ * Implements cl_object_operations::clo_io_init() method for lov
+ * layer. Dispatches to the appropriate layout io initialization method.
+ */
+int lov_io_init(const struct lu_env *env, struct cl_object *obj,
+               struct cl_io *io)
+{
+       CL_IO_SLICE_CLEAN(lov_env_io(env), lis_cl);
+       return LOV_2DISPATCH_MAYLOCK(cl2lov(obj), llo_io_init,
+                                    !io->ci_ignore_layout, env, obj, io);
+}
+
+/**
+ * An implementation of cl_object_operations::clo_attr_get() method for lov
+ * layer. For raid0 layout this collects and merges attributes of all
+ * sub-objects.
+ */
+static int lov_attr_get(const struct lu_env *env, struct cl_object *obj,
+                       struct cl_attr *attr)
+{
+       /* do not take lock, as this function is called under a
+        * spin-lock. Layout is protected from changing by ongoing IO. */
+       return LOV_2DISPATCH_NOLOCK(cl2lov(obj), llo_getattr, env, obj, attr);
+}
+
+static int lov_attr_set(const struct lu_env *env, struct cl_object *obj,
+                       const struct cl_attr *attr, unsigned valid)
+{
+       /*
+        * No dispatch is required here, as no layout implements this.
+        */
+       return 0;
+}
+
+int lov_lock_init(const struct lu_env *env, struct cl_object *obj,
+                 struct cl_lock *lock, const struct cl_io *io)
+{
+       /* No need to lock because we've taken one refcount of layout.  */
+       return LOV_2DISPATCH_NOLOCK(cl2lov(obj), llo_lock_init, env, obj, lock,
+                                   io);
+}
+
+static const struct cl_object_operations lov_ops = {
+       .coo_page_init = lov_page_init,
+       .coo_lock_init = lov_lock_init,
+       .coo_io_init   = lov_io_init,
+       .coo_attr_get  = lov_attr_get,
+       .coo_attr_set  = lov_attr_set,
+       .coo_conf_set  = lov_conf_set
+};
+
+static const struct lu_object_operations lov_lu_obj_ops = {
+       .loo_object_init      = lov_object_init,
+       .loo_object_delete    = lov_object_delete,
+       .loo_object_release   = NULL,
+       .loo_object_free      = lov_object_free,
+       .loo_object_print     = lov_object_print,
+       .loo_object_invariant = NULL
+};
+
+struct lu_object *lov_object_alloc(const struct lu_env *env,
+                                  const struct lu_object_header *unused,
+                                  struct lu_device *dev)
+{
+       struct lov_object *lov;
+       struct lu_object  *obj;
+
+       OBD_SLAB_ALLOC_PTR_GFP(lov, lov_object_kmem, GFP_NOFS);
+       if (lov != NULL) {
+               obj = lov2lu(lov);
+               lu_object_init(obj, NULL, dev);
+               lov->lo_cl.co_ops = &lov_ops;
+               lov->lo_type = -1; /* invalid, to catch uninitialized type */
+               /*
+                * object io operation vector (cl_object::co_iop) is installed
+                * later in lov_object_init(), as different vectors are used
+                * for object with different layouts.
+                */
+               obj->lo_ops = &lov_lu_obj_ops;
+       } else
+               obj = NULL;
+       return obj;
+}
+
+struct lov_stripe_md *lov_lsm_addref(struct lov_object *lov)
+{
+       struct lov_stripe_md *lsm = NULL;
+
+       lov_conf_freeze(lov);
+       if (lov->lo_lsm != NULL) {
+               lsm = lsm_addref(lov->lo_lsm);
+               CDEBUG(D_INODE, "lsm %p addref %d/%d by %p.\n",
+                       lsm, atomic_read(&lsm->lsm_refc),
+                       lov->lo_layout_invalid, current);
+       }
+       lov_conf_thaw(lov);
+       return lsm;
+}
+
+void lov_lsm_decref(struct lov_object *lov, struct lov_stripe_md *lsm)
+{
+       if (lsm == NULL)
+               return;
+
+       CDEBUG(D_INODE, "lsm %p decref %d by %p.\n",
+               lsm, atomic_read(&lsm->lsm_refc), current);
+
+       lov_free_memmd(&lsm);
+}
+
+struct lov_stripe_md *lov_lsm_get(struct cl_object *clobj)
+{
+       struct lu_object *luobj;
+       struct lov_stripe_md *lsm = NULL;
+
+       if (clobj == NULL)
+               return NULL;
+
+       luobj = lu_object_locate(&cl_object_header(clobj)->coh_lu,
+                                &lov_device_type);
+       if (luobj != NULL)
+               lsm = lov_lsm_addref(lu2lov(luobj));
+       return lsm;
+}
+EXPORT_SYMBOL(lov_lsm_get);
+
+void lov_lsm_put(struct cl_object *unused, struct lov_stripe_md *lsm)
+{
+       if (lsm != NULL)
+               lov_free_memmd(&lsm);
+}
+EXPORT_SYMBOL(lov_lsm_put);
+
+int lov_read_and_clear_async_rc(struct cl_object *clob)
+{
+       struct lu_object *luobj;
+       int rc = 0;
+
+       luobj = lu_object_locate(&cl_object_header(clob)->coh_lu,
+                                &lov_device_type);
+       if (luobj != NULL) {
+               struct lov_object *lov = lu2lov(luobj);
+
+               lov_conf_freeze(lov);
+               switch (lov->lo_type) {
+               case LLT_RAID0: {
+                       struct lov_stripe_md *lsm;
+                       int i;
+
+                       lsm = lov->lo_lsm;
+                       LASSERT(lsm != NULL);
+                       for (i = 0; i < lsm->lsm_stripe_count; i++) {
+                               struct lov_oinfo *loi = lsm->lsm_oinfo[i];
+
+                               if (lov_oinfo_is_dummy(loi))
+                                       continue;
+
+                               if (loi->loi_ar.ar_rc && !rc)
+                                       rc = loi->loi_ar.ar_rc;
+                               loi->loi_ar.ar_rc = 0;
+                       }
+               }
+               case LLT_RELEASED:
+               case LLT_EMPTY:
+                       break;
+               default:
+                       LBUG();
+               }
+               lov_conf_thaw(lov);
+       }
+       return rc;
+}
+EXPORT_SYMBOL(lov_read_and_clear_async_rc);
+
+/** @} lov */