[fs/lustre-release.git] / lustre / lov / lov_cl_internal.h

/*
 * 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.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * Internal interfaces of LOV layer.
 *
 *   Author: Nikita Danilov <nikita.danilov@sun.com>
 */

#ifndef LOV_CL_INTERNAL_H
#define LOV_CL_INTERNAL_H

#ifdef __KERNEL__
# include <libcfs/libcfs.h>
#else
# include <liblustre.h>
#endif

#include <obd.h>
#include <cl_object.h>
#include "lov_internal.h"

/** \defgroup lov lov
 * Logical object volume layer. This layer implements data striping (raid0).
 *
 * At the lov layer top-entity (object, page, lock, io) is connected to one or
 * more sub-entities: top-object, representing a file is connected to a set of
 * sub-objects, each representing a stripe, file-level top-lock is connected
 * to a set of per-stripe sub-locks, top-page is connected to a (single)
 * sub-page, and a top-level IO is connected to a set of (potentially
 * concurrent) sub-IO's.
 *
 * Sub-object, sub-page, and sub-io have well-defined top-object and top-page
 * respectively, while a single sub-lock can be part of multiple top-locks.
 *
 * Reference counting models are different for different types of entities:
 *
 *     - top-object keeps a reference to its sub-objects, and destroys them
 *       when it is destroyed.
 *
 *     - top-page keeps a reference to its sub-page, and destroys it when it
 *       is destroyed.
 *
 *     - sub-lock keep a reference to its top-locks. Top-lock keeps a
 *       reference (and a hold, see cl_lock_hold()) on its sub-locks when it
 *       actively using them (that is, in cl_lock_state::CLS_QUEUING,
 *       cl_lock_state::CLS_ENQUEUED, cl_lock_state::CLS_HELD states). When
 *       moving into cl_lock_state::CLS_CACHED state, top-lock releases a
 *       hold. From this moment top-lock has only a 'weak' reference to its
 *       sub-locks. This reference is protected by top-lock
 *       cl_lock::cll_guard, and will be automatically cleared by the sub-lock
 *       when the latter is destroyed. When a sub-lock is canceled, a
 *       reference to it is removed from the top-lock array, and top-lock is
 *       moved into CLS_NEW state. It is guaranteed that all sub-locks exist
 *       while their top-lock is in CLS_HELD or CLS_CACHED states.
 *
 *     - IO's are not reference counted.
 *
 * To implement a connection between top and sub entities, lov layer is split
 * into two pieces: lov ("upper half"), and lovsub ("bottom half"), both
 * implementing full set of cl-interfaces. For example, top-object has vvp and
 * lov layers, and it's sub-object has lovsub and osc layers. lovsub layer is
 * used to track child-parent relationship.
 *
 * @{
 */

struct lovsub_device;
struct lovsub_object;
struct lovsub_lock;

enum lov_device_flags {
        LOV_DEV_INITIALIZED = 1 << 0
};

/*
 * Upper half.
 */

/**
 * Resources that are used in memory-cleaning path, and whose allocation
 * cannot fail even when memory is tight. They are preallocated in sufficient
 * quantities in lov_device::ld_emerg[], and access to them is serialized
 * lov_device::ld_mutex.
 */
struct lov_device_emerg {
        /**
         * Page list used to submit IO when memory is in pressure.
         */
        struct cl_page_list emrg_page_list;
        /**
         * sub-io's shared by all threads accessing this device when memory is
         * too low to allocate sub-io's dynamically.
         */
        struct cl_io        emrg_subio;
        /**
         * Environments used by sub-io's in
         * lov_device_emerg::emrg_subio.
         */
        struct lu_env      *emrg_env;
        /**
         * Refchecks for lov_device_emerg::emrg_env.
         *
         * \see cl_env_get()
         */
        int                 emrg_refcheck;
};

struct lov_device {
        /*
         * XXX Locking of lov-private data is missing.
         */
        struct cl_device          ld_cl;
        struct lov_obd           *ld_lov;
        /** size of lov_device::ld_target[] array */
        __u32                     ld_target_nr;
        struct lovsub_device    **ld_target;
        __u32                     ld_flags;

        /** Emergency resources used in memory-cleansing paths. */
        struct lov_device_emerg **ld_emrg;
        /**
         * Serializes access to lov_device::ld_emrg in low-memory
         * conditions.
         */
        cfs_mutex_t               ld_mutex;
};

/**
 * Layout type.
 */
enum lov_layout_type {
        /** empty file without body */
        LLT_EMPTY,
        /** striped file */
        LLT_RAID0,
        LLT_NR
};

/**
 * lov-specific file state.
 *
 * lov object has particular layout type, determining how top-object is built
 * on top of sub-objects. Layout type can change dynamically. When this
 * happens, lov_object::lo_type_guard semaphore is taken in exclusive mode,
 * all state pertaining to the old layout type is destroyed, and new state is
 * constructed. All object methods take said semaphore in the shared mode,
 * providing serialization against transition between layout types.
 *
 * To avoid multiple `if' or `switch' statements, selecting behavior for the
 * current layout type, object methods perform double-dispatch, invoking
 * function corresponding to the current layout type.
 */
struct lov_object {
        struct cl_object       lo_cl;
        /**
         * Serializes object operations with transitions between layout types.
         *
         * This semaphore is taken in shared mode by all object methods, and
         * is taken in exclusive mode when object type is changed.
         *
         * \see lov_object::lo_type
         */
        cfs_rw_semaphore_t     lo_type_guard;
        /**
         * Type of an object. Protected by lov_object::lo_type_guard.
         */
        enum lov_layout_type   lo_type;
        /**
         * True if layout is valid. This bit is cleared when layout lock
         * is lost.
         */
        unsigned               lo_lsm_invalid:1;
        /**
         * Layout metadata.
         */
        struct lov_stripe_md  *lo_lsm;
        /**
         * Waitq - wait for no one else is using lo_lsm
         */
        cfs_waitq_t            lo_waitq;

        union lov_layout_state {
                struct lov_layout_raid0 {
                        unsigned               lo_nr;
                        /**
                         * When this is true, lov_object::lo_attr contains
                         * valid up to date attributes for a top-level
                         * object. This field is reset to 0 when attributes of
                         * any sub-object change.
                         */
                        int                    lo_attr_valid;
                        /**
                         * Array of sub-objects. Allocated when top-object is
                         * created (lov_init_raid0()).
                         *
                         * Top-object is a strict master of its sub-objects:
                         * it is created before them, and outlives its
                         * children (this later is necessary so that basic
                         * functions like cl_object_top() always
                         * work). Top-object keeps a reference on every
                         * sub-object.
                         *
                         * When top-object is destroyed (lov_delete_raid0())
                         * it releases its reference to a sub-object and waits
                         * until the latter is finally destroyed.
                         */
                        struct lovsub_object **lo_sub;
                        /**
                         * protect lo_sub
                         */
                        cfs_spinlock_t         lo_sub_lock;
                        /**
                         * Cached object attribute, built from sub-object
                         * attributes.
                         */
                        struct cl_attr         lo_attr;
                } raid0;
                struct lov_layout_state_empty {
                } empty;
        } u;
        /**
         * Thread that acquired lov_object::lo_type_guard in an exclusive
         * mode.
         */
        cfs_task_t            *lo_owner;
};

/**
 * Flags that top-lock can set on each of its sub-locks.
 */
enum lov_sub_flags {
        /** Top-lock acquired a hold (cl_lock_hold()) on a sub-lock. */
        LSF_HELD = 1 << 0
};

/**
 * State lov_lock keeps for each sub-lock.
 */
struct lov_lock_sub {
        /** sub-lock itself */
        struct lovsub_lock  *sub_lock;
        /** An array of per-sub-lock flags, taken from enum lov_sub_flags */
        unsigned             sub_flags;
        int                  sub_stripe;
        struct cl_lock_descr sub_descr;
        struct cl_lock_descr sub_got;
};

/**
 * lov-specific lock state.
 */
struct lov_lock {
        struct cl_lock_slice   lls_cl;
        /** Number of sub-locks in this lock */
        int                    lls_nr;
        /**
         * Number of existing sub-locks.
         */
        unsigned               lls_nr_filled;
        /**
         * Set when sub-lock was canceled, while top-lock was being
         * used, or unused.
         */
        int                    lls_cancel_race:1;
        /**
         * An array of sub-locks
         *
         * There are two issues with managing sub-locks:
         *
         *     - sub-locks are concurrently canceled, and
         *
         *     - sub-locks are shared with other top-locks.
         *
         * To manage cancellation, top-lock acquires a hold on a sublock
         * (lov_sublock_adopt()) when the latter is inserted into
         * lov_lock::lls_sub[]. This hold is released (lov_sublock_release())
         * when top-lock is going into CLS_CACHED state or destroyed. Hold
         * prevents sub-lock from cancellation.
         *
         * Sub-lock sharing means, among other things, that top-lock that is
         * in the process of creation (i.e., not yet inserted into lock list)
         * is already accessible to other threads once at least one of its
         * sub-locks is created, see lov_lock_sub_init().
         *
         * Sub-lock can be in one of the following states:
         *
         *     - doesn't exist, lov_lock::lls_sub[]::sub_lock == NULL. Such
         *       sub-lock was either never created (top-lock is in CLS_NEW
         *       state), or it was created, then canceled, then destroyed
         *       (lov_lock_unlink() cleared sub-lock pointer in the top-lock).
         *
         *     - sub-lock exists and is on
         *       hold. (lov_lock::lls_sub[]::sub_flags & LSF_HELD). This is a
         *       normal state of a sub-lock in CLS_HELD and CLS_CACHED states
         *       of a top-lock.
         *
         *     - sub-lock exists, but is not held by the top-lock. This
         *       happens after top-lock released a hold on sub-locks before
         *       going into cache (lov_lock_unuse()).
         *
         * \todo To support wide-striping, array has to be replaced with a set
         * of queues to avoid scanning.
         */
        struct lov_lock_sub   *lls_sub;
        /**
         * Original description with which lock was enqueued.
         */
        struct cl_lock_descr   lls_orig;
};

struct lov_page {
        struct cl_page_slice lps_cl;
        int                  lps_invalid;
};

/*
 * Bottom half.
 */

struct lovsub_device {
        struct cl_device   acid_cl;
        struct lov_device *acid_super;
        int                acid_idx;
        struct cl_device  *acid_next;
};

struct lovsub_object {
        struct cl_object_header lso_header;
        struct cl_object        lso_cl;
        struct lov_object      *lso_super;
        int                     lso_index;
};

/**
 * A link between a top-lock and a sub-lock. Separate data-structure is
 * necessary, because top-locks and sub-locks are in M:N relationship.
 *
 * \todo This can be optimized for a (by far) most frequent case of a single
 * top-lock per sub-lock.
 */
struct lov_lock_link {
        struct lov_lock *lll_super;
        /** An index within parent lock. */
        int              lll_idx;
        /**
         * A linkage into per sub-lock list of all corresponding top-locks,
         * hanging off lovsub_lock::lss_parents.
         */
        cfs_list_t       lll_list;
};

/**
 * Lock state at lovsub layer.
 */
struct lovsub_lock {
        struct cl_lock_slice  lss_cl;
        /**
         * List of top-locks that have given sub-lock as their part. Protected
         * by cl_lock::cll_guard mutex.
         */
        cfs_list_t            lss_parents;
        /**
         * Top-lock that initiated current operation on this sub-lock. This is
         * only set during top-to-bottom lock operations like enqueue, and is
         * used to optimize state change notification. Protected by
         * cl_lock::cll_guard mutex.
         *
         * \see lovsub_lock_state_one().
         */
        struct cl_lock       *lss_active;
};

/**
 * Describe the environment settings for sublocks.
 */
struct lov_sublock_env {
        const struct lu_env *lse_env;
        struct cl_io        *lse_io;
        struct lov_io_sub   *lse_sub;
};

struct lovsub_page {
        struct cl_page_slice lsb_cl;
};


struct lov_thread_info {
        struct cl_object_conf   lti_stripe_conf;
        struct lu_fid           lti_fid;
        struct cl_lock_descr    lti_ldescr;
        struct ost_lvb          lti_lvb;
        struct cl_2queue        lti_cl2q;
        union  lov_layout_state lti_state;
        struct cl_lock_closure  lti_closure;
        cfs_waitlink_t          lti_waiter;
};

/**
 * State that lov_io maintains for every sub-io.
 */
struct lov_io_sub {
        int                  sub_stripe;
        /**
         * sub-io for a stripe. Ideally sub-io's can be stopped and resumed
         * independently, with lov acting as a scheduler to maximize overall
         * throughput.
         */
        struct cl_io        *sub_io;
        /**
         * Linkage into a list (hanging off lov_io::lis_active) of all
         * sub-io's active for the current IO iteration.
         */
        cfs_list_t           sub_linkage;
        /**
         * true, iff cl_io_init() was successfully executed against
         * lov_io_sub::sub_io.
         */
        int                  sub_io_initialized;
        /**
         * True, iff lov_io_sub::sub_io and lov_io_sub::sub_env weren't
         * allocated, but borrowed from a per-device emergency pool.
         */
        int                  sub_borrowed;
        /**
         * environment, in which sub-io executes.
         */
        struct lu_env *sub_env;
        /**
         * environment's refcheck.
         *
         * \see cl_env_get()
         */
        int                  sub_refcheck;
        int                  sub_refcheck2;
        int                  sub_reenter;
        void                *sub_cookie;
};

/**
 * IO state private for LOV.
 */
struct lov_io {
        /** super-class */
        struct cl_io_slice lis_cl;
        /**
         * Pointer to the object slice. This is a duplicate of
         * lov_io::lis_cl::cis_object.
         */
        struct lov_object *lis_object;
        /**
         * Lov stripe - this determines how this io fans out.
         * Hold a refcount to the lsm so it can't go away during IO.
         */
        struct lov_stripe_md *lis_lsm;
        /**
         * Original end-of-io position for this IO, set by the upper layer as
         * cl_io::u::ci_rw::pos + cl_io::u::ci_rw::count. lov remembers this,
         * changes pos and count to fit IO into a single stripe and uses saved
         * value to determine when IO iterations have to stop.
         *
         * This is used only for CIT_READ and CIT_WRITE io's.
         */
        loff_t             lis_io_endpos;

        /**
         * starting position within a file, for the current io loop iteration
         * (stripe), used by ci_io_loop().
         */
        obd_off            lis_pos;
        /**
         * end position with in a file, for the current stripe io. This is
         * exclusive (i.e., next offset after last byte affected by io).
         */
        obd_off            lis_endpos;

        int                lis_mem_frozen;
        int                lis_stripe_count;
        int                lis_active_subios;

        /**
         * the index of ls_single_subio in ls_subios array
         */
        int                lis_single_subio_index;
        struct cl_io       lis_single_subio;

        /**
         * size of ls_subios array, actually the highest stripe #
         */
        int                lis_nr_subios;
        struct lov_io_sub *lis_subs;
        /**
         * List of active sub-io's.
         */
        cfs_list_t         lis_active;
};

struct lov_session {
        struct lov_io          ls_io;
        struct lov_sublock_env ls_subenv;
};

/**
 * State of transfer for lov.
 */
struct lov_req {
        struct cl_req_slice lr_cl;
};

/**
 * State of transfer for lovsub.
 */
struct lovsub_req {
        struct cl_req_slice lsrq_cl;
};

extern struct lu_device_type lov_device_type;
extern struct lu_device_type lovsub_device_type;

extern struct lu_context_key lov_key;
extern struct lu_context_key lov_session_key;

extern cfs_mem_cache_t *lov_page_kmem;
extern cfs_mem_cache_t *lov_lock_kmem;
extern cfs_mem_cache_t *lov_object_kmem;
extern cfs_mem_cache_t *lov_thread_kmem;
extern cfs_mem_cache_t *lov_session_kmem;
extern cfs_mem_cache_t *lov_req_kmem;

extern cfs_mem_cache_t *lovsub_page_kmem;
extern cfs_mem_cache_t *lovsub_lock_kmem;
extern cfs_mem_cache_t *lovsub_object_kmem;
extern cfs_mem_cache_t *lovsub_req_kmem;

extern cfs_mem_cache_t *lov_lock_link_kmem;

int   lov_object_init     (const struct lu_env *env, struct lu_object *obj,
                           const struct lu_object_conf *conf);
int   lovsub_object_init  (const struct lu_env *env, struct lu_object *obj,
                           const struct lu_object_conf *conf);
int   lov_lock_init       (const struct lu_env *env, struct cl_object *obj,
                           struct cl_lock *lock, const struct cl_io *io);
int   lov_io_init         (const struct lu_env *env, struct cl_object *obj,
                           struct cl_io *io);
int   lovsub_lock_init    (const struct lu_env *env, struct cl_object *obj,
                           struct cl_lock *lock, const struct cl_io *io);

int   lov_lock_init_raid0 (const struct lu_env *env, struct cl_object *obj,
                           struct cl_lock *lock, const struct cl_io *io);
int   lov_io_init_raid0   (const struct lu_env *env, struct cl_object *obj,
                           struct cl_io *io);
int   lov_io_init_empty   (const struct lu_env *env, struct cl_object *obj,
                           struct cl_io *io);
void  lov_lock_unlink     (const struct lu_env *env, struct lov_lock_link *link,
                           struct lovsub_lock *sub);

struct lov_io_sub *lov_sub_get(const struct lu_env *env, struct lov_io *lio,
                               int stripe);
void  lov_sub_put             (struct lov_io_sub *sub);
int   lov_sublock_modify  (const struct lu_env *env, struct lov_lock *lov,
                           struct lovsub_lock *sublock,
                           const struct cl_lock_descr *d, int idx);


struct cl_page *lov_page_init   (const struct lu_env *env, struct cl_object *ob,
                                 struct cl_page *page, cfs_page_t *vmpage);
struct cl_page *lovsub_page_init(const struct lu_env *env, struct cl_object *ob,
                                 struct cl_page *page, cfs_page_t *vmpage);

struct cl_page   *lov_page_init_empty(const struct lu_env *env,
                                      struct cl_object *obj,
                                      struct cl_page *page, cfs_page_t *vmpage);
struct cl_page   *lov_page_init_raid0(const struct lu_env *env,
                                      struct cl_object *obj,
                                      struct cl_page *page, cfs_page_t *vmpage);
struct lu_object *lov_object_alloc   (const struct lu_env *env,
                                      const struct lu_object_header *hdr,
                                      struct lu_device *dev);
struct lu_object *lovsub_object_alloc(const struct lu_env *env,
                                      const struct lu_object_header *hdr,
                                      struct lu_device *dev);

struct lov_lock_link *lov_lock_link_find(const struct lu_env *env,
                                         struct lov_lock *lck,
                                         struct lovsub_lock *sub);
struct lov_io_sub    *lov_page_subio    (const struct lu_env *env,
                                         struct lov_io *lio,
                                         const struct cl_page_slice *slice);

void lov_lsm_decref(struct lov_object *lov, struct lov_stripe_md *lsm);
struct lov_stripe_md *lov_lsm_addref(struct lov_object *lov);

#define lov_foreach_target(lov, var)                    \
        for (var = 0; var < lov_targets_nr(lov); ++var)

/*****************************************************************************
 *
 * Type conversions.
 *
 * Accessors.
 *
 */

static inline struct lov_session *lov_env_session(const struct lu_env *env)
{
        struct lov_session *ses;

        ses = lu_context_key_get(env->le_ses, &lov_session_key);
        LASSERT(ses != NULL);
        return ses;
}

static inline struct lov_io *lov_env_io(const struct lu_env *env)
{
        return &lov_env_session(env)->ls_io;
}

static inline int lov_is_object(const struct lu_object *obj)
{
        return obj->lo_dev->ld_type == &lov_device_type;
}

static inline int lovsub_is_object(const struct lu_object *obj)
{
        return obj->lo_dev->ld_type == &lovsub_device_type;
}

static inline struct lu_device *lov2lu_dev(struct lov_device *lov)
{
        return &lov->ld_cl.cd_lu_dev;
}

static inline struct lov_device *lu2lov_dev(const struct lu_device *d)
{
        LINVRNT(d->ld_type == &lov_device_type);
        return container_of0(d, struct lov_device, ld_cl.cd_lu_dev);
}

static inline struct cl_device *lovsub2cl_dev(struct lovsub_device *lovsub)
{
        return &lovsub->acid_cl;
}

static inline struct lu_device *lovsub2lu_dev(struct lovsub_device *lovsub)
{
        return &lovsub2cl_dev(lovsub)->cd_lu_dev;
}

static inline struct lovsub_device *lu2lovsub_dev(const struct lu_device *d)
{
        LINVRNT(d->ld_type == &lovsub_device_type);
        return container_of0(d, struct lovsub_device, acid_cl.cd_lu_dev);
}

static inline struct lovsub_device *cl2lovsub_dev(const struct cl_device *d)
{
        LINVRNT(d->cd_lu_dev.ld_type == &lovsub_device_type);
        return container_of0(d, struct lovsub_device, acid_cl);
}

static inline struct lu_object *lov2lu(struct lov_object *lov)
{
        return &lov->lo_cl.co_lu;
}

static inline struct cl_object *lov2cl(struct lov_object *lov)
{
        return &lov->lo_cl;
}

static inline struct lov_object *lu2lov(const struct lu_object *obj)
{
        LINVRNT(lov_is_object(obj));
        return container_of0(obj, struct lov_object, lo_cl.co_lu);
}

static inline struct lov_object *cl2lov(const struct cl_object *obj)
{
        LINVRNT(lov_is_object(&obj->co_lu));
        return container_of0(obj, struct lov_object, lo_cl);
}

static inline struct lu_object *lovsub2lu(struct lovsub_object *los)
{
        return &los->lso_cl.co_lu;
}

static inline struct cl_object *lovsub2cl(struct lovsub_object *los)
{
        return &los->lso_cl;
}

static inline struct lovsub_object *cl2lovsub(const struct cl_object *obj)
{
        LINVRNT(lovsub_is_object(&obj->co_lu));
        return container_of0(obj, struct lovsub_object, lso_cl);
}

static inline struct lovsub_object *lu2lovsub(const struct lu_object *obj)
{
        LINVRNT(lovsub_is_object(obj));
        return container_of0(obj, struct lovsub_object, lso_cl.co_lu);
}

static inline struct lovsub_lock *
cl2lovsub_lock(const struct cl_lock_slice *slice)
{
        LINVRNT(lovsub_is_object(&slice->cls_obj->co_lu));
        return container_of(slice, struct lovsub_lock, lss_cl);
}

static inline struct lovsub_lock *cl2sub_lock(const struct cl_lock *lock)
{
        const struct cl_lock_slice *slice;

        slice = cl_lock_at(lock, &lovsub_device_type);
        LASSERT(slice != NULL);
        return cl2lovsub_lock(slice);
}

static inline struct lov_lock *cl2lov_lock(const struct cl_lock_slice *slice)
{
        LINVRNT(lov_is_object(&slice->cls_obj->co_lu));
        return container_of(slice, struct lov_lock, lls_cl);
}

static inline struct lov_page *cl2lov_page(const struct cl_page_slice *slice)
{
        LINVRNT(lov_is_object(&slice->cpl_obj->co_lu));
        return container_of0(slice, struct lov_page, lps_cl);
}

static inline struct lov_req *cl2lov_req(const struct cl_req_slice *slice)
{
        return container_of0(slice, struct lov_req, lr_cl);
}

static inline struct lovsub_page *
cl2lovsub_page(const struct cl_page_slice *slice)
{
        LINVRNT(lovsub_is_object(&slice->cpl_obj->co_lu));
        return container_of0(slice, struct lovsub_page, lsb_cl);
}

static inline struct lovsub_req *cl2lovsub_req(const struct cl_req_slice *slice)
{
        return container_of0(slice, struct lovsub_req, lsrq_cl);
}

static inline struct cl_page *lov_sub_page(const struct cl_page_slice *slice)
{
        return slice->cpl_page->cp_child;
}

static inline struct lov_io *cl2lov_io(const struct lu_env *env,
                                const struct cl_io_slice *ios)
{
        struct lov_io *lio;

        lio = container_of(ios, struct lov_io, lis_cl);
        LASSERT(lio == lov_env_io(env));
        return lio;
}

static inline int lov_targets_nr(const struct lov_device *lov)
{
        return lov->ld_lov->desc.ld_tgt_count;
}

static inline struct lov_thread_info *lov_env_info(const struct lu_env *env)
{
        struct lov_thread_info *info;

        info = lu_context_key_get(&env->le_ctx, &lov_key);
        LASSERT(info != NULL);
        return info;
}

static inline struct lov_layout_raid0 *lov_r0(struct lov_object *lov)
{
        LASSERT(lov->lo_type == LLT_RAID0);
        LASSERT(lov->lo_lsm->lsm_wire.lw_magic == LOV_MAGIC ||
                lov->lo_lsm->lsm_wire.lw_magic == LOV_MAGIC_V3);
        return &lov->u.raid0;
}

/** @} lov */

#endif