[fs/lustre-release.git] / lustre / include / obd.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.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2017, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 */

#ifndef __OBD_H
#define __OBD_H

#include <linux/fs.h>
#include <linux/posix_acl.h>
#include <linux/kobject.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>
#include <linux/xarray.h>

#include <uapi/linux/lustre/lustre_idl.h>
#include <lustre_lib.h>
#include <libcfs/bitmap.h>
#ifdef HAVE_SERVER_SUPPORT
# include <lu_target.h>
# include <obd_target.h>
# include <lustre_quota.h>
#endif
#include <lu_ref.h>
#include <lustre_export.h>
#include <lustre_fid.h>
#include <lustre_fld.h>
#include <lustre_handles.h>
#include <lustre_intent.h>
#include <lvfs.h>

#define MAX_OBD_DEVICES 8192

struct osc_async_rc {
        int     ar_rc;
        int     ar_force_sync;
        __u64   ar_min_xid;
};

struct lov_oinfo {                 /* per-stripe data structure */
        struct ost_id   loi_oi;    /* object ID/Sequence on the target OST */
        int loi_ost_idx;           /* OST stripe index in lov_tgt_desc->tgts */
        int loi_ost_gen;           /* generation of this loi_ost_idx */

        unsigned long loi_kms_valid:1;
        __u64 loi_kms;             /* known minimum size */
        struct ost_lvb loi_lvb;
        struct osc_async_rc     loi_ar;
};

void lov_fix_ea_for_replay(void *lovea);

static inline void loi_kms_set(struct lov_oinfo *oinfo, __u64 kms)
{
        oinfo->loi_kms = kms;
        oinfo->loi_kms_valid = 1;
}

struct lov_stripe_md;
struct obd_info;

typedef int (*obd_enqueue_update_f)(void *cookie, int rc);

/* obd info for a particular level (lov, osc). */
struct obd_info {
        /* OBD_STATFS_* flags */
        __u64                   oi_flags;
        struct obd_device      *oi_obd;
        struct lu_tgt_desc     *oi_tgt;
        /* statfs data specific for every OSC, if needed at all. */
        struct obd_statfs      *oi_osfs;
        /* An update callback which is called to update some data on upper
         * level. E.g. it is used for update lsm->lsm_oinfo at every received
         * request in osc level for enqueue requests. It is also possible to
         * update some caller data from LOV layer if needed. */
        obd_enqueue_update_f    oi_cb_up;
};

struct obd_type {
        const struct obd_ops    *typ_dt_ops;
        const struct md_ops     *typ_md_ops;
        struct proc_dir_entry   *typ_procroot;
        struct dentry           *typ_debugfs_entry;
#ifdef HAVE_SERVER_SUPPORT
        bool                     typ_sym_filter;
#endif
        atomic_t                 typ_refcnt;
        struct lu_device_type   *typ_lu;
        struct kobject           typ_kobj;
};
#define typ_name typ_kobj.name
#define OBD_LU_TYPE_SETUP ((void *)0x01UL)

struct brw_page {
        u64              off;
        struct page     *pg;
        u32              count;
        u32              flag;
        /* used for encryption: difference with offset in clear text page */
        u16              bp_off_diff;
        /* used for encryption: difference with count in clear text page */
        u16              bp_count_diff;
        u32              bp_padding;
};

struct timeout_item {
        enum timeout_event ti_event;
        time64_t           ti_timeout;
        timeout_cb_t       ti_cb;
        void              *ti_cb_data;
        struct list_head   ti_obd_list;
        struct list_head   ti_chain;
};

#define OBD_MAX_RIF_DEFAULT     8
#define OBD_MAX_RIF_MAX         512
#define OSC_MAX_RIF_MAX         256
#define OSC_MAX_DIRTY_DEFAULT   2000     /* Arbitrary large value */
#define OSC_MAX_DIRTY_MB_MAX    2048     /* arbitrary, but < MAX_LONG bytes */
#define OSC_DEFAULT_RESENDS     10

/* possible values for lut_sync_lock_cancel */
enum tgt_sync_lock_cancel {
        SYNC_LOCK_CANCEL_NEVER    = 0,
        SYNC_LOCK_CANCEL_BLOCKING = 1,
        SYNC_LOCK_CANCEL_ALWAYS   = 2,
};

/*
 * Limit reply buffer size for striping data to one x86_64 page. This
 * value is chosen to fit the striping data for common use cases while
 * staying well below the limit at which the buffer must be backed by
 * vmalloc(). Excessive use of vmalloc() may cause spinlock contention
 * on the MDS.
 */
#define OBD_MAX_DEFAULT_EA_SIZE 4096

/*
 * Lustre can handle larger xattrs internally, but we must respect the Linux
 * VFS limitation or tools like tar cannot interact with Lustre volumes
 * correctly.
 */
#define OBD_MAX_EA_SIZE         XATTR_SIZE_MAX


enum obd_cl_sem_lock_class {
        OBD_CLI_SEM_NORMAL,
        OBD_CLI_SEM_MGC,
        OBD_CLI_SEM_MDCOSC,
};

struct mdc_rpc_lock;
struct obd_import;
struct client_obd {
        struct rw_semaphore      cl_sem;
        struct obd_uuid          cl_target_uuid;
        struct obd_import       *cl_import; /* ptlrpc connection state */
        size_t                   cl_conn_count;

        /* Cache maximum and default values for easize. This is
         * strictly a performance optimization to minimize calls to
         * obd_size_diskmd(). The default values are used to calculate the
         * initial size of a request buffer. The ptlrpc layer will resize the
         * buffer as needed to accommodate a larger reply from the
         * server. The default values should be small enough to avoid wasted
         * memory and excessive use of vmalloc(), yet large enough to avoid
         * reallocating the buffer in the common use case. */

        /* Default EA size for striping attributes. It is initialized at
         * mount-time based on the default stripe width of the filesystem,
         * then it tracks the largest observed EA size advertised by
         * the MDT, up to a maximum value of OBD_MAX_DEFAULT_EA_SIZE. */
        __u32                    cl_default_mds_easize;

        /* Maximum possible EA size computed at mount-time based on
         * the number of OSTs in the filesystem. May be increased at
         * run-time if a larger observed size is advertised by the MDT. */
        __u32                    cl_max_mds_easize;

        /* Data-on-MDT specific value to set larger reply buffer for possible
         * data read along with open/stat requests. By default it tries to use
         * unused space in reply buffer.
         * This value is used to ensure that reply buffer has at least as
         * much free space as value indicates. That free space is gained from
         * LOV EA buffer which is small for DoM files and on big systems can
         * provide up to 32KB of extra space in reply buffer.
         * Default value is 8K now.
         */
        __u32                    cl_dom_min_inline_repsize;

        unsigned int             cl_checksum:1, /* 0 = disabled, 1 = enabled */
                                 cl_checksum_dump:1, /* same */
                                 cl_ocd_grant_param:1;
        enum lustre_sec_part     cl_sp_me;
        enum lustre_sec_part     cl_sp_to;
        struct sptlrpc_flavor    cl_flvr_mgc; /* fixed flavor of mgc->mgs */

        /* the grant values are protected by loi_list_lock below */
        unsigned long            cl_dirty_pages;      /* all _dirty_ in pages */
        unsigned long            cl_dirty_max_pages;  /* allowed w/o rpc */
        unsigned long            cl_avail_grant;   /* bytes of credit for ost */
        unsigned long            cl_lost_grant;    /* lost credits (trunc) */
        /* grant consumed for dirty pages */
        unsigned long            cl_dirty_grant;

        /* since we allocate grant by blocks, we don't know how many grant will
         * be used to add a page into cache. As a solution, we reserve maximum
         * grant before trying to dirty a page and unreserve the rest.
         * See osc_{reserve|unreserve}_grant for details. */
        long                    cl_reserved_grant;
        wait_queue_head_t       cl_cache_waiters; /* waiting for cache/grant */
        time64_t                cl_next_shrink_grant;   /* seconds */
        struct list_head        cl_grant_chain;
        time64_t                cl_grant_shrink_interval; /* seconds */

        int                     cl_root_squash; /* if root squash enabled*/

        /* A chunk is an optimal size used by osc_extent to determine
         * the extent size. A chunk is max(PAGE_SIZE, OST block size) */
        int                     cl_chunkbits;
        /* extent insertion metadata overhead to be accounted in grant,
         * in bytes */
        unsigned int            cl_grant_extent_tax;
        /* maximum extent size, in number of pages */
        unsigned int            cl_max_extent_pages;

        /* keep track of objects that have lois that contain pages which
         * have been queued for async brw.  this lock also protects the
         * lists of osc_client_pages that hang off of the loi */
        /*
         * ->cl_loi_list_lock protects consistency of
         * ->cl_loi_{ready,read,write}_list. ->ap_make_ready() and
         * ->ap_completion() call-backs are executed under this lock. As we
         * cannot guarantee that these call-backs never block on all platforms
         * (as a matter of fact they do block on Mac OS X), type of
         * ->cl_loi_list_lock is platform dependent: it's a spin-lock on Linux
         * and blocking mutex on Mac OS X. (Alternative is to make this lock
         * blocking everywhere, but we don't want to slow down fast-path of
         * our main platform.)
         *
         * NB by Jinshan: though field names are still _loi_, but actually
         * osc_object{}s are in the list.
         */
        spinlock_t              cl_loi_list_lock;
        struct list_head        cl_loi_ready_list;
        struct list_head        cl_loi_hp_ready_list;
        struct list_head        cl_loi_write_list;
        struct list_head        cl_loi_read_list;
        __u32                   cl_r_in_flight;
        __u32                   cl_w_in_flight;
        /* just a sum of the loi/lop pending numbers to be exported by /proc */
        atomic_t                cl_pending_w_pages;
        atomic_t                cl_pending_r_pages;
        u32                     cl_max_pages_per_rpc;
        u32                     cl_max_rpcs_in_flight;
        u32                     cl_max_short_io_bytes;
        struct obd_histogram    cl_read_rpc_hist;
        struct obd_histogram    cl_write_rpc_hist;
        struct obd_histogram    cl_read_page_hist;
        struct obd_histogram    cl_write_page_hist;
        struct obd_histogram    cl_read_offset_hist;
        struct obd_histogram    cl_write_offset_hist;

        /** LRU for osc caching pages */
        struct cl_client_cache  *cl_cache;
        /** member of cl_cache->ccc_lru */
        struct list_head         cl_lru_osc;
        /** # of available LRU slots left in the per-OSC cache.
         * Available LRU slots are shared by all OSCs of the same file system,
         * therefore this is a pointer to cl_client_cache::ccc_lru_left. */
        atomic_long_t           *cl_lru_left;
        /** # of busy LRU pages. A page is considered busy if it's in writeback
         * queue, or in transfer. Busy pages can't be discarded so they are not
         * in LRU cache. */
        atomic_long_t            cl_lru_busy;
        /** # of LRU pages in the cache for this client_obd */
        atomic_long_t            cl_lru_in_list;
        /** # of threads are shrinking LRU cache. To avoid contention, it's not
         * allowed to have multiple threads shrinking LRU cache. */
        atomic_t                 cl_lru_shrinkers;
        /** The time when this LRU cache was last used. */
        time64_t                 cl_lru_last_used;
        /** stats: how many reclaims have happened for this client_obd.
         * reclaim and shrink - shrink is async, voluntarily rebalancing;
         * reclaim is sync, initiated by IO thread when the LRU slots are
         * in shortage. */
        __u64                    cl_lru_reclaim;
        /** List of LRU pages for this client_obd */
        struct list_head         cl_lru_list;
        /** Lock for LRU page list */
        spinlock_t               cl_lru_list_lock;
        /** # of unstable pages in this client_obd.
         * An unstable page is a page state that WRITE RPC has finished but
         * the transaction has NOT yet committed. */
        atomic_long_t            cl_unstable_count;
        /** Link to osc_shrinker_list */
        struct list_head         cl_shrink_list;

        /* number of in flight destroy rpcs is limited to max_rpcs_in_flight */
        atomic_t                 cl_destroy_in_flight;
        wait_queue_head_t        cl_destroy_waitq;

        /* modify rpcs in flight
         * currently used for metadata only */
        spinlock_t               cl_mod_rpcs_lock;
        __u16                    cl_max_mod_rpcs_in_flight;
        __u16                    cl_mod_rpcs_in_flight;
        __u16                    cl_close_rpcs_in_flight;
        wait_queue_head_t        cl_mod_rpcs_waitq;
        unsigned long           *cl_mod_tag_bitmap;
        struct obd_histogram     cl_mod_rpcs_hist;

        /* mgc datastruct */
        struct mutex              cl_mgc_mutex;
        struct local_oid_storage *cl_mgc_los;
        struct dt_object         *cl_mgc_configs_dir;
        struct obd_export        *cl_mgc_mgsexp;
        atomic_t                  cl_mgc_refcount;
        /* in-flight control list and total RPCs counter */
        struct list_head         cl_flight_waiters;
        __u32                    cl_rpcs_in_flight;

        /* supported checksum types that are worked out at connect time */
        __u32                    cl_supp_cksum_types;
        /* checksum algorithm to be used */
        enum cksum_types         cl_cksum_type;
        /* preferred checksum algorithm to be used */
        enum cksum_types         cl_preferred_cksum_type;

        /* also protected by the poorly named _loi_list_lock lock above */
        struct osc_async_rc      cl_ar;

        /* sequence manager */
        struct lu_client_seq    *cl_seq;
        struct rw_semaphore      cl_seq_rwsem;

        atomic_t                 cl_resends; /* resend count */

        /* ptlrpc work for writeback in ptlrpcd context */
        void                    *cl_writeback_work;
        void                    *cl_lru_work;
        struct mutex              cl_quota_mutex;
        /* hash tables for osc_quota_info */
        struct cfs_hash         *cl_quota_hash[LL_MAXQUOTAS];
        /* the xid of the request updating the hash tables */
        __u64                    cl_quota_last_xid;
        /* Links to the global list of registered changelog devices */
        struct list_head         cl_chg_dev_linkage;
};
#define obd2cli_tgt(obd) ((char *)(obd)->u.cli.cl_target_uuid.uuid)

struct obd_id_info {
        u32      idx;
        u64     *data;
};

struct echo_client_obd {
        struct obd_export      *ec_exp; /* the local connection to osc/lov */
        spinlock_t              ec_lock;
        struct list_head        ec_objects;
        struct list_head        ec_locks;
        __u64                   ec_unique;
};

/* allow statfs data caching for 1 second */
#define OBD_STATFS_CACHE_SECONDS 1
/* arbitrary maximum. larger would be useless, allows catching bogus input */
#define OBD_STATFS_CACHE_MAX_AGE 3600 /* seconds */

#define lov_tgt_desc lu_tgt_desc

struct lov_md_tgt_desc {
        struct obd_device *lmtd_mdc;
        __u32              lmtd_index;
};

struct lov_obd {
        struct lov_desc         desc;
        struct lov_tgt_desc   **lov_tgts;               /* sparse array */
        struct lu_tgt_pool      lov_packed;             /* all OSTs in a packed
                                                           array */
        struct mutex            lov_lock;
        struct obd_connect_data lov_ocd;
        atomic_t                lov_refcount;
        __u32                   lov_death_row;  /* tgts scheduled to be deleted */
        __u32                   lov_tgt_size;   /* size of tgts array */
        int                     lov_connects;
        int                     lov_pool_count;
        struct rhashtable       lov_pools_hash_body; /* used for key access */
        struct list_head        lov_pool_list;  /* used for sequential access */
        struct proc_dir_entry  *lov_pool_proc_entry;
        enum lustre_sec_part    lov_sp_me;

        /* Cached LRU and unstable data from upper layer */
        struct cl_client_cache *lov_cache;

        struct rw_semaphore     lov_notify_lock;
        /* Data-on-MDT: MDC array */
        struct lov_md_tgt_desc  *lov_mdc_tgts;

        struct kobject          *lov_tgts_kobj;
};

#define lmv_tgt_desc lu_tgt_desc

struct lmv_obd {
        struct lu_client_fld    lmv_fld;
        spinlock_t              lmv_lock;

        int                     connected;
        int                     max_easize;
        int                     max_def_easize;
        u32                     lmv_statfs_start;

        struct lu_tgt_descs     lmv_mdt_descs;

        struct obd_connect_data conn_data;
        struct kobject          *lmv_tgts_kobj;
        void                    *lmv_cache;

        __u32                   lmv_qos_rr_index;
};

#define lmv_mdt_count   lmv_mdt_descs.ltd_lmv_desc.ld_tgt_count
#define lmv_qos         lmv_mdt_descs.ltd_qos

/* Minimum sector size is 512 */
#define MAX_GUARD_NUMBER (PAGE_SIZE / 512)

struct niobuf_local {
        __u64           lnb_file_offset;
        __u32           lnb_page_offset;
        __u32           lnb_len;
        __u32           lnb_flags;
        int             lnb_rc;
        struct page     *lnb_page;
        void            *lnb_data;
        __u16           lnb_guards[MAX_GUARD_NUMBER];
        __u16           lnb_guard_rpc:1;
        __u16           lnb_guard_disk:1;
        /* separate unlock for read path to allow shared access */
        __u16           lnb_locked:1;
};

struct tgt_thread_big_cache {
        struct niobuf_local     local[PTLRPC_MAX_BRW_PAGES];
};

#define LUSTRE_FLD_NAME         "fld"
#define LUSTRE_SEQ_NAME         "seq"

#define LUSTRE_MDD_NAME         "mdd"
#define LUSTRE_OSD_LDISKFS_NAME "osd-ldiskfs"
#define LUSTRE_OSD_ZFS_NAME     "osd-zfs"
#define LUSTRE_VVP_NAME         "vvp"
#define LUSTRE_LMV_NAME         "lmv"
#define LUSTRE_SLP_NAME         "slp"
#define LUSTRE_LOD_NAME         "lod"
#define LUSTRE_OSP_NAME         "osp"
#define LUSTRE_LWP_NAME         "lwp"

/* obd device type names */
 /* FIXME all the references to LUSTRE_MDS_NAME should be swapped with LUSTRE_MDT_NAME */
#define LUSTRE_MDS_NAME         "mds"
#define LUSTRE_MDT_NAME         "mdt"
#define LUSTRE_MDC_NAME         "mdc"
#define LUSTRE_OSS_NAME         "ost"       /* FIXME change name to oss */
#define LUSTRE_OST_NAME         "obdfilter" /* FIXME change name to ost */
#define LUSTRE_OSC_NAME         "osc"
#define LUSTRE_LOV_NAME         "lov"
#define LUSTRE_MGS_NAME         "mgs"
#define LUSTRE_MGC_NAME         "mgc"

#define LUSTRE_ECHO_NAME        "obdecho"
#define LUSTRE_ECHO_CLIENT_NAME "echo_client"
#define LUSTRE_QMT_NAME         "qmt"

/* Constant obd names (post-rename) */
#define LUSTRE_MDS_OBDNAME "MDS"
#define LUSTRE_OSS_OBDNAME "OSS"
#define LUSTRE_MGS_OBDNAME "MGS"
#define LUSTRE_MGC_OBDNAME "MGC"

static inline int is_lwp_on_mdt(char *name)
{
        char   *ptr;

        ptr = strrchr(name, '-');
        if (ptr == NULL) {
                CERROR("%s is not a obdname\n", name);
                return 0;
        }

        /* LWP name on MDT is fsname-MDTxxxx-lwp-MDTxxxx */

        if (strncmp(ptr + 1, "MDT", 3) != 0)
                return 0;

        while (*(--ptr) != '-' && ptr != name);

        if (ptr == name)
                return 0;

        if (strncmp(ptr + 1, LUSTRE_LWP_NAME, strlen(LUSTRE_LWP_NAME)) != 0)
                return 0;

        return 1;
}

static inline int is_lwp_on_ost(char *name)
{
        char   *ptr;

        ptr = strrchr(name, '-');
        if (ptr == NULL) {
                CERROR("%s is not a obdname\n", name);
                return 0;
        }

        /* LWP name on OST is fsname-MDTxxxx-lwp-OSTxxxx */

        if (strncmp(ptr + 1, "OST", 3) != 0)
                return 0;

        while (*(--ptr) != '-' && ptr != name);

        if (ptr == name)
                return 0;

        if (strncmp(ptr + 1, LUSTRE_LWP_NAME, strlen(LUSTRE_LWP_NAME)) != 0)
                return 0;

        return 1;
}

/*
 * Events signalled through obd_notify() upcall-chain.
 */
enum obd_notify_event {
        /* Device connect start */
        OBD_NOTIFY_CONNECT,
        /* Device activated */
        OBD_NOTIFY_ACTIVE,
        /* Device deactivated */
        OBD_NOTIFY_INACTIVE,
        /* Connect data for import were changed */
        OBD_NOTIFY_OCD,
        /* Administratively deactivate/activate event */
        OBD_NOTIFY_DEACTIVATE,
        OBD_NOTIFY_ACTIVATE
};

/*
 * Data structure used to pass obd_notify()-event to non-obd listeners (llite
 * being main example).
 */
struct obd_notify_upcall {
        int (*onu_upcall)(struct obd_device *host, struct obd_device *watched,
                          enum obd_notify_event ev, void *owner);
        /* Opaque datum supplied by upper layer listener */
        void *onu_owner;
};

struct target_recovery_data {
        svc_handler_t           trd_recovery_handler;
        pid_t                   trd_processing_task;
        struct completion       trd_starting;
        struct completion       trd_finishing;
};

struct obd_llog_group {
        struct llog_ctxt   *olg_ctxts[LLOG_MAX_CTXTS];
        wait_queue_head_t  olg_waitq;
        spinlock_t         olg_lock;
};

/* corresponds to one of the obd's */
#define OBD_DEVICE_MAGIC        0XAB5CD6EF

struct obd_device {
        struct obd_type                 *obd_type;
        __u32                            obd_magic; /* OBD_DEVICE_MAGIC */
        int                              obd_minor; /* device number: lctl dl */
        struct lu_device                *obd_lu_dev;

        /* common and UUID name of this device */
        struct obd_uuid                  obd_uuid;
        char                             obd_name[MAX_OBD_NAME];

        /* bitfield modification is protected by obd_dev_lock */
        unsigned long
                obd_attached:1,         /* finished attach */
                obd_set_up:1,           /* finished setup */
                obd_recovering:1,       /* there are recoverable clients */
                obd_abort_recovery:1,   /* recovery expired */
                obd_abort_recov_mdt:1,  /* only abort recovery between MDTs */
                obd_version_recov:1,    /* obd uses version checking */
                obd_replayable:1,       /* recovery enabled; inform clients */
                obd_no_recov:1,         /* fail instead of retry messages */
                obd_stopping:1,         /* started cleanup */
                obd_starting:1,         /* started setup */
                obd_force:1,            /* cleanup with > 0 obd refcount */
                obd_fail:1,             /* cleanup with failover */
                obd_no_conn:1,          /* deny new connections */
                obd_inactive:1,         /* device active/inactive
                                         * (for /proc/status only!!) */
                obd_no_ir:1,            /* no imperative recovery. */
                obd_process_conf:1,     /* device is processing mgs config */
                obd_checksum_dump:1,    /* dump pages upon cksum error */
                obd_dynamic_nids:1;     /* Allow dynamic NIDs on device */
#ifdef HAVE_SERVER_SUPPORT
        /* no committed-transno notification */
        unsigned long                   obd_no_transno:1;
#endif

        /* use separate field as it is set in interrupt to don't mess with
         * protection of other bits using _bh lock */
        unsigned long obd_recovery_expired:1;
        /* uuid-export hash body */
        struct rhashtable               obd_uuid_hash;
        /* nid-export hash body */
        struct rhltable                 obd_nid_hash;
        /* nid stats body */
        struct cfs_hash             *obd_nid_stats_hash;
        /* client_generation-export hash body */
        struct cfs_hash             *obd_gen_hash;
        struct list_head        obd_nid_stats;
        struct list_head        obd_exports;
        struct list_head        obd_unlinked_exports;
        struct list_head        obd_delayed_exports;
        struct list_head        obd_lwp_list;
        atomic_t                obd_refcount;
        int                     obd_num_exports;
        spinlock_t              obd_nid_lock;
        struct ldlm_namespace  *obd_namespace;
        struct ptlrpc_client    obd_ldlm_client; /* XXX OST/MDS only */
        /* a spinlock is OK for what we do now, may need a semaphore later */
        spinlock_t              obd_dev_lock; /* protect OBD bitfield above */
        spinlock_t              obd_osfs_lock;
        struct obd_statfs       obd_osfs;       /* locked by obd_osfs_lock */
        time64_t                obd_osfs_age;
        __u64                   obd_last_committed;
        struct mutex            obd_dev_mutex;
        struct lvfs_run_ctxt    obd_lvfs_ctxt;
        struct obd_llog_group   obd_olg;        /* default llog group */
        struct obd_device       *obd_observer;
        struct rw_semaphore     obd_observer_link_sem;
        struct obd_notify_upcall obd_upcall;
        struct obd_export       *obd_self_export;
        struct obd_export       *obd_lwp_export;
        /* list of exports in LRU order, for ping evictor, with obd_dev_lock */
        struct list_head        obd_exports_timed;
        time64_t                obd_eviction_timer;     /* for ping evictor */

        atomic_t                obd_max_recoverable_clients;
        atomic_t                obd_connected_clients;
        int                     obd_stale_clients;
        /* this lock protects all recovery list_heads, timer and
         * obd_next_recovery_transno value */
        spinlock_t              obd_recovery_task_lock;
        __u64                   obd_next_recovery_transno;
        int                     obd_replayed_requests;
        int                     obd_requests_queued_for_recovery;
        wait_queue_head_t       obd_next_transno_waitq;
        /* protected by obd_recovery_task_lock */
        struct hrtimer          obd_recovery_timer;
        /* seconds */
        time64_t                obd_recovery_start;
        /* seconds, for lprocfs_status */
        time64_t                obd_recovery_end;
        /* To tell timeouts from time stamps Lustre uses timeout_t
         * instead of time64_t.
         */
        timeout_t                       obd_recovery_time_hard;
        timeout_t                       obd_recovery_timeout;
        int                             obd_recovery_ir_factor;

        /* new recovery stuff from CMD2 */
        int                             obd_replayed_locks;
        atomic_t                        obd_req_replay_clients;
        atomic_t                        obd_lock_replay_clients;
        struct target_recovery_data     obd_recovery_data;

        /* all lists are protected by obd_recovery_task_lock */
        struct list_head                obd_req_replay_queue;
        struct list_head                obd_lock_replay_queue;
        struct list_head                obd_final_req_queue;

        union {
#ifdef HAVE_SERVER_SUPPORT
                struct obd_device_target obt;
                struct filter_obd filter;
                struct ost_obd ost;
                struct echo_obd echo;
#endif
                struct client_obd cli;
                struct echo_client_obd echo_client;
                struct lov_obd lov;
                struct lmv_obd lmv;
        } u;

        /* Fields used by LProcFS */
        struct lprocfs_stats            *obd_stats;

        struct lprocfs_stats            *obd_md_stats;

        struct dentry                   *obd_debugfs_entry;
        struct proc_dir_entry   *obd_proc_entry;
        struct proc_dir_entry   *obd_proc_exports_entry;
        struct dentry                   *obd_svc_debugfs_entry;
        struct lprocfs_stats    *obd_svc_stats;
        const struct attribute         **obd_attrs;
        struct lprocfs_vars     *obd_vars;
        struct ldebugfs_vars    *obd_debugfs_vars;
        atomic_t                obd_evict_inprogress;
        wait_queue_head_t       obd_evict_inprogress_waitq;
        struct list_head        obd_evict_list; /* protected with pet_lock */

        /**
         * LDLM pool part. Save last calculated SLV and Limit.
         */
        rwlock_t                        obd_pool_lock;
        __u64                           obd_pool_slv;
        int                             obd_pool_limit;

        int                             obd_conn_inprogress;

        /**
         * List of outstanding class_incref()'s fo this OBD. For debugging. */
        struct lu_ref                   obd_reference;

        struct kset                     obd_kset; /* sysfs object collection */
        struct kobj_type                obd_ktype;
        struct completion               obd_kobj_unregister;
};

int obd_uuid_add(struct obd_device *obd, struct obd_export *export);
void obd_uuid_del(struct obd_device *obd, struct obd_export *export);
#ifdef HAVE_SERVER_SUPPORT
struct obd_export *obd_uuid_lookup(struct obd_device *obd,
                                   struct obd_uuid *uuid);

int obd_nid_export_for_each(struct obd_device *obd, lnet_nid_t nid,
                            int cb(struct obd_export *exp, void *data),
                            void *data);
int obd_nid_add(struct obd_device *obd, struct obd_export *exp);
void obd_nid_del(struct obd_device *obd, struct obd_export *exp);
#endif

/* get/set_info keys */
#define KEY_ASYNC               "async"
#define KEY_CHANGELOG_CLEAR     "changelog_clear"
#define KEY_FID2PATH            "fid2path"
#define KEY_CHECKSUM            "checksum"
#define KEY_CLEAR_FS            "clear_fs"
#define KEY_CONN_DATA           "conn_data"
#define KEY_EVICT_BY_NID        "evict_by_nid"
#define KEY_FIEMAP              "fiemap"
#define KEY_FLUSH_CTX           "flush_ctx"
#define KEY_GRANT_SHRINK        "grant_shrink"
#define KEY_HSM_COPYTOOL_SEND   "hsm_send"
#define KEY_INIT_RECOV_BACKUP   "init_recov_bk"
#define KEY_INTERMDS            "inter_mds"
#define KEY_LAST_ID             "last_id"
#define KEY_LAST_FID            "last_fid"
#define KEY_MAX_EASIZE          "max_easize"
#define KEY_DEFAULT_EASIZE      "default_easize"
#define KEY_MGSSEC              "mgssec"
#define KEY_READ_ONLY           "read-only"
#define KEY_REGISTER_TARGET     "register_target"
#define KEY_SET_FS              "set_fs"
#define KEY_TGT_COUNT           "tgt_count"
/*      KEY_SET_INFO in lustre_idl.h */
#define KEY_SPTLRPC_CONF        "sptlrpc_conf"

#define KEY_CACHE_LRU_SHRINK    "cache_lru_shrink"
#define KEY_OSP_CONNECTED       "osp_connected"

/* Flags for op_xvalid */
enum op_xvalid {
        OP_XVALID_CTIME_SET     = BIT(0),       /* 0x0001 */
        OP_XVALID_BLOCKS        = BIT(1),       /* 0x0002 */
        OP_XVALID_OWNEROVERRIDE = BIT(2),       /* 0x0004 */
        OP_XVALID_FLAGS         = BIT(3),       /* 0x0008 */
        OP_XVALID_PROJID        = BIT(4),       /* 0x0010 */
        OP_XVALID_LAZYSIZE      = BIT(5),       /* 0x0020 */
        OP_XVALID_LAZYBLOCKS    = BIT(6),       /* 0x0040 */
};

struct lu_context;

static inline int it_to_lock_mode(struct lookup_intent *it)
{
        /* CREAT needs to be tested before open (both could be set) */
        if (it->it_op & IT_CREAT)
                return LCK_CW;
        else if (it->it_op & (IT_GETATTR | IT_OPEN | IT_LOOKUP))
                return LCK_CR;
        else if (it->it_op & IT_LAYOUT)
                return (it->it_flags & FMODE_WRITE) ? LCK_EX : LCK_CR;
        else if (it->it_op &  IT_READDIR)
                return LCK_PR;
        else if (it->it_op &  IT_GETXATTR)
                return LCK_PR;

        LASSERTF(0, "Invalid it_op: %d\n", it->it_op);
        return -EINVAL;
}

enum md_op_flags {
        MF_MDC_CANCEL_FID1      = BIT(0),
        MF_MDC_CANCEL_FID2      = BIT(1),
        MF_MDC_CANCEL_FID3      = BIT(2),
        MF_MDC_CANCEL_FID4      = BIT(3),
        MF_GET_MDT_IDX          = BIT(4),
        MF_GETATTR_BY_FID       = BIT(5),
        MF_QOS_MKDIR            = BIT(6),
        MF_RR_MKDIR             = BIT(7),
        MF_OPNAME_KMALLOCED     = BIT(8),
};

enum md_cli_flags {
        CLI_SET_MEA     = BIT(0),
        CLI_RM_ENTRY    = BIT(1),
        CLI_HASH64      = BIT(2),
        CLI_API32       = BIT(3),
        CLI_MIGRATE     = BIT(4),
        CLI_DIRTY_DATA  = BIT(5),
};

enum md_op_code {
        LUSTRE_OPC_MKDIR = 1,
        LUSTRE_OPC_SYMLINK,
        LUSTRE_OPC_MKNOD,
        LUSTRE_OPC_CREATE,
        LUSTRE_OPC_ANY,
        LUSTRE_OPC_LOOKUP,
        LUSTRE_OPC_OPEN,
        LUSTRE_OPC_MIGR,
};

/**
 * GETXATTR is not included as only a couple of fields in the reply body
 * is filled, but not FID which is needed for common intent handling in
 * mdc_finish_intent_lock()
 */
static inline bool it_has_reply_body(const struct lookup_intent *it)
{
        return it->it_op & (IT_OPEN | IT_LOOKUP | IT_GETATTR);
}

struct md_op_data {
        struct lu_fid           op_fid1; /* operation fid1 (usualy parent) */
        struct lu_fid           op_fid2; /* operation fid2 (usualy child) */
        struct lu_fid           op_fid3; /* 2 extra fids to find conflicting */
        struct lu_fid           op_fid4; /* to the operation locks. */
        u32                     op_mds;  /* what mds server open will go to */
        __u32                   op_mode;
        enum md_op_code         op_code;
        struct lustre_handle    op_open_handle;
        s64                     op_mod_time;
        const char              *op_name;
        size_t                  op_namelen;
        struct rw_semaphore     *op_mea1_sem;
        struct rw_semaphore     *op_mea2_sem;
        struct lmv_stripe_md    *op_mea1;
        struct lmv_stripe_md    *op_mea2;
        struct lmv_stripe_md    *op_default_mea1;       /* default LMV */
        __u32                   op_suppgids[2];
        __u32                   op_fsuid;
        __u32                   op_fsgid;
        kernel_cap_t            op_cap;
        void                    *op_data;
        size_t                  op_data_size;

        /* iattr fields and blocks. */
        struct iattr            op_attr;
        enum op_xvalid          op_xvalid;      /* eXtra validity flags */
        loff_t                  op_attr_blocks;
        u64                     op_valid;       /* OBD_MD_* */
        unsigned int            op_attr_flags;  /* LUSTRE_{SYNC,..}_FL */

        enum md_op_flags        op_flags;

        /* Various operation flags. */
        enum mds_op_bias        op_bias;

        /* used to transfer info between the stacks of MD client
         * see enum op_cli_flags */
        enum md_cli_flags       op_cli_flags;

        /* File object data version for HSM release, on client */
        __u64                   op_data_version;
        struct lustre_handle    op_lease_handle;

        /* File security context, for creates/metadata ops */
        const char             *op_file_secctx_name;
        __u32                   op_file_secctx_name_size;
        void                   *op_file_secctx;
        __u32                   op_file_secctx_size;

        /* File encryption context, for creates/metadata ops */
        void                   *op_file_encctx;
        __u32                   op_file_encctx_size;

        __u32                   op_projid;

        union {
                /* Used by readdir */
                unsigned int    op_max_pages;
                /* mkdir */
                unsigned short  op_dir_depth;
        };

        __u16                   op_mirror_id;

        /*
         * used to access dir that is changing layout: if it's set, access
         * dir by new layout, otherwise old layout.
         * By default it's not set, because new files are created under new
         * layout, if we can't find file with name under both old and new
         * layout, we are sure file with name doesn't exist, but in reverse
         * order there may be a race with creation by others.
         */
        bool                    op_new_layout;
        /* used to access dir with bash hash */
        __u32                   op_stripe_index;
        /* Archive ID for PCC attach */
        __u32                   op_archive_id;
};

struct md_callback {
        int (*md_blocking_ast)(struct ldlm_lock *lock,
                               struct ldlm_lock_desc *desc,
                               void *data, int flag);
};

struct md_enqueue_info;
/* metadata stat-ahead */
typedef int (* md_enqueue_cb_t)(struct ptlrpc_request *req,
                                struct md_enqueue_info *minfo,
                                int rc);

struct md_enqueue_info {
        struct md_op_data               mi_data;
        struct lookup_intent            mi_it;
        struct lustre_handle            mi_lockh;
        struct inode                   *mi_dir;
        struct ldlm_enqueue_info        mi_einfo;
        md_enqueue_cb_t                 mi_cb;
        void                           *mi_cbdata;
};

struct obd_ops {
        struct module *o_owner;
        int (*o_iocontrol)(unsigned int cmd, struct obd_export *exp, int len,
                           void *karg, void __user *uarg);
        int (*o_get_info)(const struct lu_env *env, struct obd_export *,
                          __u32 keylen, void *key, __u32 *vallen, void *val);
        int (*o_set_info_async)(const struct lu_env *, struct obd_export *,
                                __u32 keylen, void *key,
                                __u32 vallen, void *val,
                                struct ptlrpc_request_set *set);
        int (*o_setup) (struct obd_device *obd, struct lustre_cfg *cfg);
        int (*o_precleanup)(struct obd_device *obd);
        int (*o_cleanup)(struct obd_device *obd);
        int (*o_process_config)(struct obd_device *obd, size_t len, void *data);
        int (*o_postrecov)(struct obd_device *obd);
        int (*o_add_conn)(struct obd_import *imp, struct obd_uuid *uuid,
                          int priority);
        int (*o_del_conn)(struct obd_import *imp, struct obd_uuid *uuid);
        /* connect to the target device with given connection
         * data. @ocd->ocd_connect_flags is modified to reflect flags actually
         * granted by the target, which are guaranteed to be a subset of flags
         * asked for. If @ocd == NULL, use default parameters. */
        int (*o_connect)(const struct lu_env *env,
                         struct obd_export **exp, struct obd_device *src,
                         struct obd_uuid *cluuid, struct obd_connect_data *ocd,
                         void *localdata);
        int (*o_reconnect)(const struct lu_env *env,
                           struct obd_export *exp, struct obd_device *src,
                           struct obd_uuid *cluuid,
                           struct obd_connect_data *ocd,
                           void *localdata);
        int (*o_disconnect)(struct obd_export *exp);

        /* Initialize/finalize fids infrastructure. */
        int (*o_fid_init)(struct obd_device *obd,
                          struct obd_export *exp, enum lu_cli_type type);
        int (*o_fid_fini)(struct obd_device *obd);

        /* Allocate new fid according to passed @hint. */
        int (*o_fid_alloc)(const struct lu_env *env, struct obd_export *exp,
                           struct lu_fid *fid, struct md_op_data *op_data);

        /*
         * Object with @fid is getting deleted, we may want to do something
         * about this.
         */
        int (*o_statfs)(const struct lu_env *, struct obd_export *exp,
                        struct obd_statfs *osfs, time64_t max_age, __u32 flags);
        int (*o_statfs_async)(struct obd_export *exp, struct obd_info *oinfo,
                              time64_t max_age, struct ptlrpc_request_set *set);
        int (*o_create)(const struct lu_env *env, struct obd_export *exp,
                        struct obdo *oa);
        int (*o_destroy)(const struct lu_env *env, struct obd_export *exp,
                         struct obdo *oa);
        int (*o_setattr)(const struct lu_env *, struct obd_export *exp,
                         struct obdo *oa);
        int (*o_getattr)(const struct lu_env *env, struct obd_export *exp,
                         struct obdo *oa);
        int (*o_preprw)(const struct lu_env *env, int cmd,
                        struct obd_export *exp, struct obdo *oa, int objcount,
                        struct obd_ioobj *obj, struct niobuf_remote *remote,
                        int *nr_pages, struct niobuf_local *local);
        int (*o_commitrw)(const struct lu_env *env, int cmd,
                          struct obd_export *exp, struct obdo *oa,
                          int objcount, struct obd_ioobj *obj,
                          struct niobuf_remote *remote, int pages,
                          struct niobuf_local *local, int rc);
        int (*o_init_export)(struct obd_export *exp);
        int (*o_destroy_export)(struct obd_export *exp);

        int (*o_import_event)(struct obd_device *, struct obd_import *,
                              enum obd_import_event);

        int (*o_notify)(struct obd_device *obd, struct obd_device *watched,
                        enum obd_notify_event ev);

        int (*o_health_check)(const struct lu_env *env, struct obd_device *);
        struct obd_uuid *(*o_get_uuid) (struct obd_export *exp);

        /* quota methods */
        int (*o_quotactl)(struct obd_device *, struct obd_export *,
                          struct obd_quotactl *);

        /* pools methods */
        int (*o_pool_new)(struct obd_device *obd, char *poolname);
        int (*o_pool_del)(struct obd_device *obd, char *poolname);
        int (*o_pool_add)(struct obd_device *obd, char *poolname,
                          char *ostname);
        int (*o_pool_rem)(struct obd_device *obd, char *poolname,
                          char *ostname);
};

/* lmv structures */
struct lustre_md {
        struct mdt_body         *body;
        struct lu_buf            layout;
        union {
                struct lmv_stripe_md    *lmv;
                struct lmv_foreign_md   *lfm;
        };
        struct lmv_stripe_md    *default_lmv;
#ifdef CONFIG_LUSTRE_FS_POSIX_ACL
        struct posix_acl        *posix_acl;
#endif
};

#ifdef CONFIG_LUSTRE_FS_POSIX_ACL
static inline void lmd_clear_acl(struct lustre_md *md)
{
        if (md->posix_acl) {
                posix_acl_release(md->posix_acl);
                md->posix_acl = NULL;
        }
}

#define OBD_CONNECT_ACL_FLAGS  \
        (OBD_CONNECT_ACL | OBD_CONNECT_UMASK | OBD_CONNECT_LARGE_ACL)
#else
static inline void lmd_clear_acl(struct lustre_md *md)
{
}

#define OBD_CONNECT_ACL_FLAGS  (0)
#endif

struct md_open_data {
        struct obd_client_handle        *mod_och;
        struct ptlrpc_request           *mod_open_req;
        struct ptlrpc_request           *mod_close_req;
        atomic_t                         mod_refcount;
        bool                             mod_is_create;
};

struct obd_client_handle {
        struct lustre_handle     och_open_handle;
        struct lu_fid            och_fid;
        struct md_open_data     *och_mod;
        struct lustre_handle     och_lease_handle; /* open lock for lease */
        __u32                    och_magic;
        int                      och_flags;
};

#define OBD_CLIENT_HANDLE_MAGIC 0xd15ea5ed

struct lookup_intent;
struct cl_attr;

struct md_ops {
        int (*m_close)(struct obd_export *, struct md_op_data *,
                       struct md_open_data *, struct ptlrpc_request **);

        int (*m_create)(struct obd_export *, struct md_op_data *,
                        const void *, size_t, umode_t, uid_t, gid_t,
                        kernel_cap_t, __u64, struct ptlrpc_request **);

        int (*m_enqueue)(struct obd_export *, struct ldlm_enqueue_info *,
                         const union ldlm_policy_data *, struct md_op_data *,
                         struct lustre_handle *, __u64);

        int (*m_getattr)(struct obd_export *, struct md_op_data *,
                         struct ptlrpc_request **);

        int (*m_intent_lock)(struct obd_export *, struct md_op_data *,
                             struct lookup_intent *,
                             struct ptlrpc_request **,
                             ldlm_blocking_callback, __u64);

        int (*m_link)(struct obd_export *, struct md_op_data *,
                      struct ptlrpc_request **);

        int (*m_rename)(struct obd_export *, struct md_op_data *,
                        const char *, size_t, const char *, size_t,
                        struct ptlrpc_request **);

        int (*m_setattr)(struct obd_export *, struct md_op_data *, void *,
                         size_t , struct ptlrpc_request **);

        int (*m_fsync)(struct obd_export *, const struct lu_fid *,
                       struct ptlrpc_request **);

        int (*m_read_page)(struct obd_export *, struct md_op_data *,
                           struct md_callback *cb_op, __u64 hash_offset,
                           struct page **ppage);

        int (*m_unlink)(struct obd_export *, struct md_op_data *,
                        struct ptlrpc_request **);

        int (*m_setxattr)(struct obd_export *, const struct lu_fid *,
                          u64, const char *, const void *, size_t, unsigned int,
                          u32, struct ptlrpc_request **);

        int (*m_getxattr)(struct obd_export *, const struct lu_fid *,
                          u64, const char *, size_t, struct ptlrpc_request **);

        int (*m_intent_getattr_async)(struct obd_export *,
                                      struct md_enqueue_info *);

        int (*m_revalidate_lock)(struct obd_export *, struct lookup_intent *,
                                 struct lu_fid *, __u64 *bits);

        int (*m_file_resync)(struct obd_export *, struct md_op_data *);

        int (*m_get_root)(struct obd_export *, const char *, struct lu_fid *);
        int (*m_null_inode)(struct obd_export *, const struct lu_fid *);

        int (*m_getattr_name)(struct obd_export *, struct md_op_data *,
                              struct ptlrpc_request **);

        int (*m_init_ea_size)(struct obd_export *, __u32, __u32);

        int (*m_get_lustre_md)(struct obd_export *, struct req_capsule *,
                               struct obd_export *, struct obd_export *,
                               struct lustre_md *);

        int (*m_free_lustre_md)(struct obd_export *, struct lustre_md *);

        int (*m_merge_attr)(struct obd_export *,
                            const struct lmv_stripe_md *lsm,
                            struct cl_attr *attr, ldlm_blocking_callback);

        int (*m_set_open_replay_data)(struct obd_export *,
                                      struct obd_client_handle *,
                                      struct lookup_intent *);

        int (*m_clear_open_replay_data)(struct obd_export *,
                                        struct obd_client_handle *);

        int (*m_set_lock_data)(struct obd_export *,
                               const struct lustre_handle *, void *, __u64 *);

        enum ldlm_mode (*m_lock_match)(struct obd_export *, __u64,
                                       const struct lu_fid *, enum ldlm_type,
                                       union ldlm_policy_data *, enum ldlm_mode,
                                       struct lustre_handle *);

        int (*m_cancel_unused)(struct obd_export *, const struct lu_fid *,
                               union ldlm_policy_data *, enum ldlm_mode,
                               enum ldlm_cancel_flags flags, void *opaque);

        int (*m_get_fid_from_lsm)(struct obd_export *,
                                  const struct lmv_stripe_md *,
                                  const char *name, int namelen,
                                  struct lu_fid *fid);
        int (*m_unpackmd)(struct obd_export *exp, struct lmv_stripe_md **plsm,
                          const union lmv_mds_md *lmv, size_t lmv_size);
        int (*m_rmfid)(struct obd_export *exp, struct fid_array *fa, int *rcs,
                       struct ptlrpc_request_set *set);
};

static inline struct md_open_data *obd_mod_alloc(void)
{
        struct md_open_data *mod;
        OBD_ALLOC_PTR(mod);
        if (mod == NULL)
                return NULL;
        atomic_set(&mod->mod_refcount, 1);
        return mod;
}

#define obd_mod_get(mod) atomic_inc(&(mod)->mod_refcount)
#define obd_mod_put(mod)                                          \
({                                                                \
        if (atomic_dec_and_test(&(mod)->mod_refcount)) {          \
                if ((mod)->mod_open_req)                          \
                        ptlrpc_req_finished((mod)->mod_open_req); \
                OBD_FREE_PTR(mod);                                \
        }                                                         \
})

void obdo_from_inode(struct obdo *dst, struct inode *src, u64 valid);
void obdo_set_parent_fid(struct obdo *dst, const struct lu_fid *parent);
void obdo_set_o_projid(struct obdo *dst, u32 projid);

/* return 1 if client should be resend request */
static inline int client_should_resend(int resend, struct client_obd *cli)
{
        return atomic_read(&cli->cl_resends) ?
               atomic_read(&cli->cl_resends) > resend : 1;
}

/**
 * Return device name for this device
 *
 * XXX: lu_device is declared before obd_device, while a pointer pointing
 * back to obd_device in lu_device, so this helper function defines here
 * instead of in lu_object.h
 */
static inline const char *lu_dev_name(const struct lu_device *lu_dev)
{
        return lu_dev->ld_obd->obd_name;
}

static inline bool filename_is_volatile(const char *name, size_t namelen,
                                        int *idx)
{
        const char      *start;
        char            *end;

        if (strncmp(name, LUSTRE_VOLATILE_HDR, LUSTRE_VOLATILE_HDR_LEN) != 0)
                return false;

        /* caller does not care of idx */
        if (idx == NULL)
                return true;

        /* volatile file, the MDT can be set from name */
        /* name format is LUSTRE_VOLATILE_HDR:[idx]: */
        /* if no MDT is specified, use std way */
        if (namelen < LUSTRE_VOLATILE_HDR_LEN + 2)
                goto bad_format;
        /* test for no MDT idx case */
        if ((*(name + LUSTRE_VOLATILE_HDR_LEN) == ':') &&
            (*(name + LUSTRE_VOLATILE_HDR_LEN + 1) == ':')) {
                *idx = -1;
                return true;
        }
        /* we have an idx, read it */
        start = name + LUSTRE_VOLATILE_HDR_LEN + 1;
        *idx = simple_strtoul(start, &end, 16);
        /* error cases:
         * no digit, no trailing :, negative value
         */
        if (((*idx == 0) && (end == start)) ||
            (*end != ':') || (*idx < 0))
                goto bad_format;

        return true;
bad_format:
        /* bad format of mdt idx, we cannot return an error
         * to caller so we use hash algo */
        CERROR("Bad volatile file name format: %s\n",
               name + LUSTRE_VOLATILE_HDR_LEN);
        return false;
}

static inline int cli_brw_size(struct obd_device *obd)
{
        LASSERT(obd != NULL);
        return obd->u.cli.cl_max_pages_per_rpc << PAGE_SHIFT;
}

/*
 * When RPC size or the max RPCs in flight is increased, the max dirty pages
 * of the client should be increased accordingly to avoid sending fragmented
 * RPCs over the network when the client runs out of the maximum dirty space
 * when so many RPCs are being generated.
 */
static inline void client_adjust_max_dirty(struct client_obd *cli)
{
         /* initializing */
        if (cli->cl_dirty_max_pages <= 0) {
                cli->cl_dirty_max_pages =
                        (OSC_MAX_DIRTY_DEFAULT * 1024 * 1024) >> PAGE_SHIFT;
        } else {
                unsigned long dirty_max = cli->cl_max_rpcs_in_flight *
                                          cli->cl_max_pages_per_rpc;

                if (dirty_max > cli->cl_dirty_max_pages)
                        cli->cl_dirty_max_pages = dirty_max;
        }

        if (cli->cl_dirty_max_pages > cfs_totalram_pages() / 8)
                cli->cl_dirty_max_pages = cfs_totalram_pages() / 8;

        /* This value is exported to userspace through the max_dirty_mb
         * parameter.  So we round up the number of pages to make it a round
         * number of MBs. */
        cli->cl_dirty_max_pages = round_up(cli->cl_dirty_max_pages,
                                           1 << (20 - PAGE_SHIFT));
}

static inline struct inode *page2inode(struct page *page)
{
        if (page->mapping) {
                if (PageAnon(page))
                        return NULL;
                else
                        return page->mapping->host;
        } else {
                return NULL;
        }
}

#endif /* __OBD_H */