/*
 * 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.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, 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"

/** \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, pgoff_t index);
        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);

void lov_lsm_put(struct cl_object *unused, struct lov_stripe_md *lsm)
{
        if (lsm)
                lov_free_memmd(&lsm);
}
EXPORT_SYMBOL(lov_lsm_put);

/*****************************************************************************
 *
 * 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) {
                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);
                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.", idx);
                LU_OBJECT_DEBUG(mask, env, old_obj, "owned.");
                LU_OBJECT_HEADER(mask, env, lov2lu(lov), "try to own.\n");
                cl_object_put(env, stripe);
        }
        return result;
}

static int lov_page_slice_fixup(struct lov_object *lov,
                                struct cl_object *stripe)
{
        struct cl_object_header *hdr = cl_object_header(&lov->lo_cl);
        struct cl_object *o;

        if (!stripe)
                return hdr->coh_page_bufsize - lov->lo_cl.co_slice_off -
                       cfs_size_round(sizeof(struct lov_page));

        cl_object_for_each(o, stripe)
                o->co_slice_off += hdr->coh_page_bufsize;

        return cl_object_header(stripe)->coh_page_bufsize;
}

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);
        lov->lo_lsm = lsm_addref(lsm);
        lov->lo_layout_invalid = true;
        r0->lo_nr  = lsm->lsm_stripe_count;
        LASSERT(r0->lo_nr <= lov_targets_nr(dev));

        r0->lo_sub = libcfs_kvzalloc(r0->lo_nr * sizeof(r0->lo_sub[0]),
                                     GFP_NOFS);
        if (r0->lo_sub) {
                int psz = 0;

                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, "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;
                                        continue;
                                }
                        } else {
                                result = PTR_ERR(stripe);
                        }

                        if (result == 0) {
                                int sz = lov_page_slice_fixup(lov, stripe);

                                LASSERT(ergo(psz > 0, psz == sz));
                                psz = sz;
                        }
                }
                if (result == 0)
                        cl_object_header(&lov->lo_cl)->coh_page_bufsize += psz;
        } 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);
        LASSERT(lsm_is_released(lsm));
        LASSERT(!lov->lo_lsm);

        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);
        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]);
}

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) {
                for (i = 0; i < r0->lo_nr; ++i) {
                        struct lovsub_object *los = r0->lo_sub[i];

                        if (los) {
                                cl_object_prune(env, &los->lso_cl);
                                /*
                                 * If top-level object is to be evicted from
                                 * the cache, so are its sub-objects.
                                 */
                                lov_subobject_kill(env, lov, los, i);
                        }
                }
        }
        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) {
                kvfree(r0->lo_sub);
                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]) {
                        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)
                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);
        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;

        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)
                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 = cl_object_prune(env, &lov->lo_cl);
        if (result != 0)
                goto out;

        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);

                lov->lo_type = LLT_EMPTY;
                /* page bufsize fixup */
                cl_object_header(&lov->lo_cl)->coh_page_bufsize -=
                        lov_page_slice_fixup(lov, NULL);

                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. */
                }
        }

out:
        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)
                lsm = conf->u.coc_md->lsm;
        if ((!lsm && !lov->lo_lsm) ||
            ((lsm && lov->lo_lsm) &&
             (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;
        }

        result = lov_layout_change(env, lov, conf);
        lov->lo_layout_invalid = result != 0;

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);
        kmem_cache_free(lov_object_kmem, lov);
}

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, pgoff_t index)
{
        return LOV_2DISPATCH_NOLOCK(cl2lov(obj), llo_page_init, env, obj, page,
                                    index);
}

/**
 * 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_update(const struct lu_env *env, struct cl_object *obj,
                           const struct cl_attr *attr, unsigned int 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 int lov_object_getstripe(const struct lu_env *env, struct cl_object *obj,
                                struct lov_user_md __user *lum)
{
        struct lov_object *lov = cl2lov(obj);
        struct lov_stripe_md *lsm;
        int rc = 0;

        lsm = lov_lsm_addref(lov);
        if (!lsm)
                return -ENODATA;

        rc = lov_getstripe(cl2lov(obj), lsm, lum);
        lov_lsm_put(obj, lsm);
        return rc;
}

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_update = lov_attr_update,
        .coo_conf_set  = lov_conf_set,
        .coo_getstripe = lov_object_getstripe
};

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;

        lov = kmem_cache_zalloc(lov_object_kmem, GFP_NOFS);
        if (lov) {
                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) {
                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;
}

struct lov_stripe_md *lov_lsm_get(struct cl_object *clobj)
{
        struct lu_object *luobj;
        struct lov_stripe_md *lsm = NULL;

        if (!clobj)
                return NULL;

        luobj = lu_object_locate(&cl_object_header(clobj)->coh_lu,
                                 &lov_device_type);
        if (luobj)
                lsm = lov_lsm_addref(lu2lov(luobj));

        return lsm;
}
EXPORT_SYMBOL(lov_lsm_get);

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) {
                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;
                        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 */