Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[cascardo/linux.git] / drivers / staging / lustre / lustre / include / lustre_net.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) 2010, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */
/** \defgroup PtlRPC Portal RPC and networking module.
 *
 * PortalRPC is the layer used by rest of lustre code to achieve network
 * communications: establish connections with corresponding export and import
 * states, listen for a service, send and receive RPCs.
 * PortalRPC also includes base recovery framework: packet resending and
 * replaying, reconnections, pinger.
 *
 * PortalRPC utilizes LNet as its transport layer.
 *
 * @{
 */

#ifndef _LUSTRE_NET_H
#define _LUSTRE_NET_H

/** \defgroup net net
 *
 * @{
 */

#include "../../include/linux/libcfs/libcfs.h"
#include "../../include/linux/lnet/nidstr.h"
#include "../../include/linux/lnet/api.h"
#include "lustre/lustre_idl.h"
#include "lustre_ha.h"
#include "lustre_sec.h"
#include "lustre_import.h"
#include "lprocfs_status.h"
#include "lu_object.h"
#include "lustre_req_layout.h"

#include "obd_support.h"
#include "lustre_ver.h"

/* MD flags we _always_ use */
#define PTLRPC_MD_OPTIONS  0

/**
 * Max # of bulk operations in one request.
 * In order for the client and server to properly negotiate the maximum
 * possible transfer size, PTLRPC_BULK_OPS_COUNT must be a power-of-two
 * value.  The client is free to limit the actual RPC size for any bulk
 * transfer via cl_max_pages_per_rpc to some non-power-of-two value.
 */
#define PTLRPC_BULK_OPS_BITS    2
#define PTLRPC_BULK_OPS_COUNT   (1U << PTLRPC_BULK_OPS_BITS)
/**
 * PTLRPC_BULK_OPS_MASK is for the convenience of the client only, and
 * should not be used on the server at all.  Otherwise, it imposes a
 * protocol limitation on the maximum RPC size that can be used by any
 * RPC sent to that server in the future.  Instead, the server should
 * use the negotiated per-client ocd_brw_size to determine the bulk
 * RPC count.
 */
#define PTLRPC_BULK_OPS_MASK    (~((__u64)PTLRPC_BULK_OPS_COUNT - 1))

/**
 * Define maxima for bulk I/O.
 *
 * A single PTLRPC BRW request is sent via up to PTLRPC_BULK_OPS_COUNT
 * of LNET_MTU sized RDMA transfers.  Clients and servers negotiate the
 * currently supported maximum between peers at connect via ocd_brw_size.
 */
#define PTLRPC_MAX_BRW_BITS     (LNET_MTU_BITS + PTLRPC_BULK_OPS_BITS)
#define PTLRPC_MAX_BRW_SIZE     (1 << PTLRPC_MAX_BRW_BITS)
#define PTLRPC_MAX_BRW_PAGES    (PTLRPC_MAX_BRW_SIZE >> PAGE_SHIFT)

#define ONE_MB_BRW_SIZE         (1 << LNET_MTU_BITS)
#define MD_MAX_BRW_SIZE         (1 << LNET_MTU_BITS)
#define MD_MAX_BRW_PAGES        (MD_MAX_BRW_SIZE >> PAGE_SHIFT)
#define DT_MAX_BRW_SIZE         PTLRPC_MAX_BRW_SIZE
#define DT_MAX_BRW_PAGES        (DT_MAX_BRW_SIZE >> PAGE_SHIFT)
#define OFD_MAX_BRW_SIZE        (1 << LNET_MTU_BITS)

/* When PAGE_SIZE is a constant, we can check our arithmetic here with cpp! */
# if ((PTLRPC_MAX_BRW_PAGES & (PTLRPC_MAX_BRW_PAGES - 1)) != 0)
#  error "PTLRPC_MAX_BRW_PAGES isn't a power of two"
# endif
# if (PTLRPC_MAX_BRW_SIZE != (PTLRPC_MAX_BRW_PAGES * PAGE_SIZE))
#  error "PTLRPC_MAX_BRW_SIZE isn't PTLRPC_MAX_BRW_PAGES * PAGE_SIZE"
# endif
# if (PTLRPC_MAX_BRW_SIZE > LNET_MTU * PTLRPC_BULK_OPS_COUNT)
#  error "PTLRPC_MAX_BRW_SIZE too big"
# endif
# if (PTLRPC_MAX_BRW_PAGES > LNET_MAX_IOV * PTLRPC_BULK_OPS_COUNT)
#  error "PTLRPC_MAX_BRW_PAGES too big"
# endif

#define PTLRPC_NTHRS_INIT       2

/**
 * Buffer Constants
 *
 * Constants determine how memory is used to buffer incoming service requests.
 *
 * ?_NBUFS            # buffers to allocate when growing the pool
 * ?_BUFSIZE        # bytes in a single request buffer
 * ?_MAXREQSIZE  # maximum request service will receive
 *
 * When fewer than ?_NBUFS/2 buffers are posted for receive, another chunk
 * of ?_NBUFS is added to the pool.
 *
 * Messages larger than ?_MAXREQSIZE are dropped.  Request buffers are
 * considered full when less than ?_MAXREQSIZE is left in them.
 */
/**
 * Thread Constants
 *
 * Constants determine how threads are created for ptlrpc service.
 *
 * ?_NTHRS_INIT         # threads to create for each service partition on
 *                        initializing. If it's non-affinity service and
 *                        there is only one partition, it's the overall #
 *                        threads for the service while initializing.
 * ?_NTHRS_BASE         # threads should be created at least for each
 *                        ptlrpc partition to keep the service healthy.
 *                        It's the low-water mark of threads upper-limit
 *                        for each partition.
 * ?_THR_FACTOR  # threads can be added on threads upper-limit for
 *                        each CPU core. This factor is only for reference,
 *                        we might decrease value of factor if number of cores
 *                        per CPT is above a limit.
 * ?_NTHRS_MAX          # overall threads can be created for a service,
 *                        it's a soft limit because if service is running
 *                        on machine with hundreds of cores and tens of
 *                        CPU partitions, we need to guarantee each partition
 *                        has ?_NTHRS_BASE threads, which means total threads
 *                        will be ?_NTHRS_BASE * number_of_cpts which can
 *                        exceed ?_NTHRS_MAX.
 *
 * Examples
 *
 * #define MDS_NTHRS_INIT       2
 * #define MDS_NTHRS_BASE       64
 * #define MDS_NTHRS_FACTOR     8
 * #define MDS_NTHRS_MAX        1024
 *
 * Example 1):
 * ---------------------------------------------------------------------
 * Server(A) has 16 cores, user configured it to 4 partitions so each
 * partition has 4 cores, then actual number of service threads on each
 * partition is:
 *     MDS_NTHRS_BASE(64) + cores(4) * MDS_NTHRS_FACTOR(8) = 96
 *
 * Total number of threads for the service is:
 *     96 * partitions(4) = 384
 *
 * Example 2):
 * ---------------------------------------------------------------------
 * Server(B) has 32 cores, user configured it to 4 partitions so each
 * partition has 8 cores, then actual number of service threads on each
 * partition is:
 *     MDS_NTHRS_BASE(64) + cores(8) * MDS_NTHRS_FACTOR(8) = 128
 *
 * Total number of threads for the service is:
 *     128 * partitions(4) = 512
 *
 * Example 3):
 * ---------------------------------------------------------------------
 * Server(B) has 96 cores, user configured it to 8 partitions so each
 * partition has 12 cores, then actual number of service threads on each
 * partition is:
 *     MDS_NTHRS_BASE(64) + cores(12) * MDS_NTHRS_FACTOR(8) = 160
 *
 * Total number of threads for the service is:
 *     160 * partitions(8) = 1280
 *
 * However, it's above the soft limit MDS_NTHRS_MAX, so we choose this number
 * as upper limit of threads number for each partition:
 *     MDS_NTHRS_MAX(1024) / partitions(8) = 128
 *
 * Example 4):
 * ---------------------------------------------------------------------
 * Server(C) have a thousand of cores and user configured it to 32 partitions
 *     MDS_NTHRS_BASE(64) * 32 = 2048
 *
 * which is already above soft limit MDS_NTHRS_MAX(1024), but we still need
 * to guarantee that each partition has at least MDS_NTHRS_BASE(64) threads
 * to keep service healthy, so total number of threads will just be 2048.
 *
 * NB: we don't suggest to choose server with that many cores because backend
 *     filesystem itself, buffer cache, or underlying network stack might
 *     have some SMP scalability issues at that large scale.
 *
 *     If user already has a fat machine with hundreds or thousands of cores,
 *     there are two choices for configuration:
 *     a) create CPU table from subset of all CPUs and run Lustre on
 *      top of this subset
 *     b) bind service threads on a few partitions, see modparameters of
 *      MDS and OSS for details
*
 * NB: these calculations (and examples below) are simplified to help
 *     understanding, the real implementation is a little more complex,
 *     please see ptlrpc_server_nthreads_check() for details.
 *
 */

 /*
  * LDLM threads constants:
  *
  * Given 8 as factor and 24 as base threads number
  *
  * example 1)
  * On 4-core machine we will have 24 + 8 * 4 = 56 threads.
  *
  * example 2)
  * On 8-core machine with 2 partitions we will have 24 + 4 * 8 = 56
  * threads for each partition and total threads number will be 112.
  *
  * example 3)
  * On 64-core machine with 8 partitions we will need LDLM_NTHRS_BASE(24)
  * threads for each partition to keep service healthy, so total threads
  * number should be 24 * 8 = 192.
  *
  * So with these constants, threads number will be at the similar level
  * of old versions, unless target machine has over a hundred cores
  */
#define LDLM_THR_FACTOR         8
#define LDLM_NTHRS_INIT         PTLRPC_NTHRS_INIT
#define LDLM_NTHRS_BASE         24
#define LDLM_NTHRS_MAX          (num_online_cpus() == 1 ? 64 : 128)

#define LDLM_BL_THREADS   LDLM_NTHRS_AUTO_INIT
#define LDLM_CLIENT_NBUFS 1
#define LDLM_SERVER_NBUFS 64
#define LDLM_BUFSIZE      (8 * 1024)
#define LDLM_MAXREQSIZE   (5 * 1024)
#define LDLM_MAXREPSIZE   (1024)

#define MDS_MAXREQSIZE          (5 * 1024)      /* >= 4736 */

#define OST_MAXREQSIZE          (5 * 1024)

/* Macro to hide a typecast. */
#define ptlrpc_req_async_args(req) ((void *)&req->rq_async_args)

struct ptlrpc_replay_async_args {
        int             praa_old_state;
        int             praa_old_status;
};

/**
 * Structure to single define portal connection.
 */
struct ptlrpc_connection {
        /** linkage for connections hash table */
        struct hlist_node       c_hash;
        /** Our own lnet nid for this connection */
        lnet_nid_t            c_self;
        /** Remote side nid for this connection */
        lnet_process_id_t       c_peer;
        /** UUID of the other side */
        struct obd_uuid  c_remote_uuid;
        /** reference counter for this connection */
        atomic_t            c_refcount;
};

/** Client definition for PortalRPC */
struct ptlrpc_client {
        /** What lnet portal does this client send messages to by default */
        __u32              cli_request_portal;
        /** What portal do we expect replies on */
        __u32              cli_reply_portal;
        /** Name of the client */
        char               *cli_name;
};

/** state flags of requests */
/* XXX only ones left are those used by the bulk descs as well! */
#define PTL_RPC_FL_INTR      (1 << 0)  /* reply wait was interrupted by user */
#define PTL_RPC_FL_TIMEOUT   (1 << 7)  /* request timed out waiting for reply */

#define REQ_MAX_ACK_LOCKS 8

union ptlrpc_async_args {
        /**
         * Scratchpad for passing args to completion interpreter. Users
         * cast to the struct of their choosing, and CLASSERT that this is
         * big enough.  For _tons_ of context, kmalloc a struct and store
         * a pointer to it here.  The pointer_arg ensures this struct is at
         * least big enough for that.
         */
        void      *pointer_arg[11];
        __u64      space[7];
};

struct ptlrpc_request_set;
typedef int (*set_interpreter_func)(struct ptlrpc_request_set *, void *, int);
typedef int (*set_producer_func)(struct ptlrpc_request_set *, void *);

/**
 * Definition of request set structure.
 * Request set is a list of requests (not necessary to the same target) that
 * once populated with RPCs could be sent in parallel.
 * There are two kinds of request sets. General purpose and with dedicated
 * serving thread. Example of the latter is ptlrpcd set.
 * For general purpose sets once request set started sending it is impossible
 * to add new requests to such set.
 * Provides a way to call "completion callbacks" when all requests in the set
 * returned.
 */
struct ptlrpc_request_set {
        atomic_t          set_refcount;
        /** number of in queue requests */
        atomic_t          set_new_count;
        /** number of uncompleted requests */
        atomic_t          set_remaining;
        /** wait queue to wait on for request events */
        wait_queue_head_t          set_waitq;
        wait_queue_head_t         *set_wakeup_ptr;
        /** List of requests in the set */
        struct list_head            set_requests;
        /**
         * List of completion callbacks to be called when the set is completed
         * This is only used if \a set_interpret is NULL.
         * Links struct ptlrpc_set_cbdata.
         */
        struct list_head            set_cblist;
        /** Completion callback, if only one. */
        set_interpreter_func  set_interpret;
        /** opaq argument passed to completion \a set_interpret callback. */
        void             *set_arg;
        /**
         * Lock for \a set_new_requests manipulations
         * locked so that any old caller can communicate requests to
         * the set holder who can then fold them into the lock-free set
         */
        spinlock_t              set_new_req_lock;
        /** List of new yet unsent requests. Only used with ptlrpcd now. */
        struct list_head            set_new_requests;

        /** rq_status of requests that have been freed already */
        int                set_rc;
        /** Additional fields used by the flow control extension */
        /** Maximum number of RPCs in flight */
        int                set_max_inflight;
        /** Callback function used to generate RPCs */
        set_producer_func     set_producer;
        /** opaq argument passed to the producer callback */
        void             *set_producer_arg;
};

/**
 * Description of a single ptrlrpc_set callback
 */
struct ptlrpc_set_cbdata {
        /** List linkage item */
        struct list_head              psc_item;
        /** Pointer to interpreting function */
        set_interpreter_func    psc_interpret;
        /** Opaq argument to pass to the callback */
        void               *psc_data;
};

struct ptlrpc_bulk_desc;
struct ptlrpc_service_part;
struct ptlrpc_service;

/**
 * ptlrpc callback & work item stuff
 */
struct ptlrpc_cb_id {
        void   (*cbid_fn)(lnet_event_t *ev);     /* specific callback fn */
        void    *cbid_arg;                    /* additional arg */
};

/** Maximum number of locks to fit into reply state */
#define RS_MAX_LOCKS 8
#define RS_DEBUG     0

/**
 * Structure to define reply state on the server
 * Reply state holds various reply message information. Also for "difficult"
 * replies (rep-ack case) we store the state after sending reply and wait
 * for the client to acknowledge the reception. In these cases locks could be
 * added to the state for replay/failover consistency guarantees.
 */
struct ptlrpc_reply_state {
        /** Callback description */
        struct ptlrpc_cb_id    rs_cb_id;
        /** Linkage for list of all reply states in a system */
        struct list_head             rs_list;
        /** Linkage for list of all reply states on same export */
        struct list_head             rs_exp_list;
        /** Linkage for list of all reply states for same obd */
        struct list_head             rs_obd_list;
#if RS_DEBUG
        struct list_head             rs_debug_list;
#endif
        /** A spinlock to protect the reply state flags */
        spinlock_t              rs_lock;
        /** Reply state flags */
        unsigned long     rs_difficult:1; /* ACK/commit stuff */
        unsigned long     rs_no_ack:1;    /* no ACK, even for
                                           * difficult requests
                                           */
        unsigned long     rs_scheduled:1;     /* being handled? */
        unsigned long     rs_scheduled_ever:1;/* any schedule attempts? */
        unsigned long     rs_handled:1;  /* been handled yet? */
        unsigned long     rs_on_net:1;   /* reply_out_callback pending? */
        unsigned long     rs_prealloc:1; /* rs from prealloc list */
        unsigned long     rs_committed:1;/* the transaction was committed
                                          * and the rs was dispatched
                                          */
        /** Size of the state */
        int                 rs_size;
        /** opcode */
        __u32             rs_opc;
        /** Transaction number */
        __u64             rs_transno;
        /** xid */
        __u64             rs_xid;
        struct obd_export     *rs_export;
        struct ptlrpc_service_part *rs_svcpt;
        /** Lnet metadata handle for the reply */
        lnet_handle_md_t       rs_md_h;
        atomic_t           rs_refcount;

        /** Context for the service thread */
        struct ptlrpc_svc_ctx *rs_svc_ctx;
        /** Reply buffer (actually sent to the client), encoded if needed */
        struct lustre_msg     *rs_repbuf;       /* wrapper */
        /** Size of the reply buffer */
        int                 rs_repbuf_len;   /* wrapper buf length */
        /** Size of the reply message */
        int                 rs_repdata_len;  /* wrapper msg length */
        /**
         * Actual reply message. Its content is encrypted (if needed) to
         * produce reply buffer for actual sending. In simple case
         * of no network encryption we just set \a rs_repbuf to \a rs_msg
         */
        struct lustre_msg     *rs_msg;    /* reply message */

        /** Number of locks awaiting client ACK */
        int                 rs_nlocks;
        /** Handles of locks awaiting client reply ACK */
        struct lustre_handle   rs_locks[RS_MAX_LOCKS];
        /** Lock modes of locks in \a rs_locks */
        enum ldlm_mode      rs_modes[RS_MAX_LOCKS];
};

struct ptlrpc_thread;

/** RPC stages */
enum rq_phase {
        RQ_PHASE_NEW        = 0xebc0de00,
        RQ_PHASE_RPC        = 0xebc0de01,
        RQ_PHASE_BULK      = 0xebc0de02,
        RQ_PHASE_INTERPRET      = 0xebc0de03,
        RQ_PHASE_COMPLETE       = 0xebc0de04,
        RQ_PHASE_UNREG_RPC      = 0xebc0de05,
        RQ_PHASE_UNREG_BULK     = 0xebc0de06,
        RQ_PHASE_UNDEFINED      = 0xebc0de07
};

/** Type of request interpreter call-back */
typedef int (*ptlrpc_interpterer_t)(const struct lu_env *env,
                                    struct ptlrpc_request *req,
                                    void *arg, int rc);

/**
 * Definition of request pool structure.
 * The pool is used to store empty preallocated requests for the case
 * when we would actually need to send something without performing
 * any allocations (to avoid e.g. OOM).
 */
struct ptlrpc_request_pool {
        /** Locks the list */
        spinlock_t prp_lock;
        /** list of ptlrpc_request structs */
        struct list_head prp_req_list;
        /** Maximum message size that would fit into a request from this pool */
        int prp_rq_size;
        /** Function to allocate more requests for this pool */
        int (*prp_populate)(struct ptlrpc_request_pool *, int);
};

struct lu_context;
struct lu_env;

struct ldlm_lock;

/**
 * \defgroup nrs Network Request Scheduler
 * @{
 */
struct ptlrpc_nrs_policy;
struct ptlrpc_nrs_resource;
struct ptlrpc_nrs_request;

/**
 * NRS control operations.
 *
 * These are common for all policies.
 */
enum ptlrpc_nrs_ctl {
        /**
         * Not a valid opcode.
         */
        PTLRPC_NRS_CTL_INVALID,
        /**
         * Activate the policy.
         */
        PTLRPC_NRS_CTL_START,
        /**
         * Reserved for multiple primary policies, which may be a possibility
         * in the future.
         */
        PTLRPC_NRS_CTL_STOP,
        /**
         * Policies can start using opcodes from this value and onwards for
         * their own purposes; the assigned value itself is arbitrary.
         */
        PTLRPC_NRS_CTL_1ST_POL_SPEC = 0x20,
};

/**
 * ORR policy operations
 */
enum nrs_ctl_orr {
        NRS_CTL_ORR_RD_QUANTUM = PTLRPC_NRS_CTL_1ST_POL_SPEC,
        NRS_CTL_ORR_WR_QUANTUM,
        NRS_CTL_ORR_RD_OFF_TYPE,
        NRS_CTL_ORR_WR_OFF_TYPE,
        NRS_CTL_ORR_RD_SUPP_REQ,
        NRS_CTL_ORR_WR_SUPP_REQ,
};

/**
 * NRS policy operations.
 *
 * These determine the behaviour of a policy, and are called in response to
 * NRS core events.
 */
struct ptlrpc_nrs_pol_ops {
        /**
         * Called during policy registration; this operation is optional.
         *
         * \param[in,out] policy The policy being initialized
         */
        int     (*op_policy_init) (struct ptlrpc_nrs_policy *policy);
        /**
         * Called during policy unregistration; this operation is optional.
         *
         * \param[in,out] policy The policy being unregistered/finalized
         */
        void    (*op_policy_fini) (struct ptlrpc_nrs_policy *policy);
        /**
         * Called when activating a policy via lprocfs; policies allocate and
         * initialize their resources here; this operation is optional.
         *
         * \param[in,out] policy The policy being started
         *
         * \see nrs_policy_start_locked()
         */
        int     (*op_policy_start) (struct ptlrpc_nrs_policy *policy);
        /**
         * Called when deactivating a policy via lprocfs; policies deallocate
         * their resources here; this operation is optional
         *
         * \param[in,out] policy The policy being stopped
         *
         * \see nrs_policy_stop0()
         */
        void    (*op_policy_stop) (struct ptlrpc_nrs_policy *policy);
        /**
         * Used for policy-specific operations; i.e. not generic ones like
         * \e PTLRPC_NRS_CTL_START and \e PTLRPC_NRS_CTL_GET_INFO; analogous
         * to an ioctl; this operation is optional.
         *
         * \param[in,out]        policy The policy carrying out operation \a opc
         * \param[in]     opc    The command operation being carried out
         * \param[in,out] arg    An generic buffer for communication between the
         *                       user and the control operation
         *
         * \retval -ve error
         * \retval   0 success
         *
         * \see ptlrpc_nrs_policy_control()
         */
        int     (*op_policy_ctl) (struct ptlrpc_nrs_policy *policy,
                                  enum ptlrpc_nrs_ctl opc, void *arg);

        /**
         * Called when obtaining references to the resources of the resource
         * hierarchy for a request that has arrived for handling at the PTLRPC
         * service. Policies should return -ve for requests they do not wish
         * to handle. This operation is mandatory.
         *
         * \param[in,out] policy  The policy we're getting resources for.
         * \param[in,out] nrq     The request we are getting resources for.
         * \param[in]     parent  The parent resource of the resource being
         *                        requested; set to NULL if none.
         * \param[out]    resp    The resource is to be returned here; the
         *                        fallback policy in an NRS head should
         *                        \e always return a non-NULL pointer value.
         * \param[in]  moving_req When set, signifies that this is an attempt
         *                        to obtain resources for a request being moved
         *                        to the high-priority NRS head by
         *                        ldlm_lock_reorder_req().
         *                        This implies two things:
         *                        1. We are under obd_export::exp_rpc_lock and
         *                        so should not sleep.
         *                        2. We should not perform non-idempotent or can
         *                        skip performing idempotent operations that
         *                        were carried out when resources were first
         *                        taken for the request when it was initialized
         *                        in ptlrpc_nrs_req_initialize().
         *
         * \retval 0, +ve The level of the returned resource in the resource
         *                hierarchy; currently only 0 (for a non-leaf resource)
         *                and 1 (for a leaf resource) are supported by the
         *                framework.
         * \retval -ve    error
         *
         * \see ptlrpc_nrs_req_initialize()
         * \see ptlrpc_nrs_hpreq_add_nolock()
         */
        int     (*op_res_get) (struct ptlrpc_nrs_policy *policy,
                               struct ptlrpc_nrs_request *nrq,
                               const struct ptlrpc_nrs_resource *parent,
                               struct ptlrpc_nrs_resource **resp,
                               bool moving_req);
        /**
         * Called when releasing references taken for resources in the resource
         * hierarchy for the request; this operation is optional.
         *
         * \param[in,out] policy The policy the resource belongs to
         * \param[in] res        The resource to be freed
         *
         * \see ptlrpc_nrs_req_finalize()
         * \see ptlrpc_nrs_hpreq_add_nolock()
         */
        void    (*op_res_put) (struct ptlrpc_nrs_policy *policy,
                               const struct ptlrpc_nrs_resource *res);

        /**
         * Obtains a request for handling from the policy, and optionally
         * removes the request from the policy; this operation is mandatory.
         *
         * \param[in,out] policy The policy to poll
         * \param[in]     peek   When set, signifies that we just want to
         *                       examine the request, and not handle it, so the
         *                       request is not removed from the policy.
         * \param[in]     force  When set, it will force a policy to return a
         *                       request if it has one queued.
         *
         * \retval NULL No request available for handling
         * \retval valid-pointer The request polled for handling
         *
         * \see ptlrpc_nrs_req_get_nolock()
         */
        struct ptlrpc_nrs_request *
                (*op_req_get) (struct ptlrpc_nrs_policy *policy, bool peek,
                               bool force);
        /**
         * Called when attempting to add a request to a policy for later
         * handling; this operation is mandatory.
         *
         * \param[in,out] policy  The policy on which to enqueue \a nrq
         * \param[in,out] nrq The request to enqueue
         *
         * \retval 0    success
         * \retval != 0 error
         *
         * \see ptlrpc_nrs_req_add_nolock()
         */
        int     (*op_req_enqueue) (struct ptlrpc_nrs_policy *policy,
                                   struct ptlrpc_nrs_request *nrq);
        /**
         * Removes a request from the policy's set of pending requests. Normally
         * called after a request has been polled successfully from the policy
         * for handling; this operation is mandatory.
         *
         * \param[in,out] policy The policy the request \a nrq belongs to
         * \param[in,out] nrq    The request to dequeue
         */
        void    (*op_req_dequeue) (struct ptlrpc_nrs_policy *policy,
                                   struct ptlrpc_nrs_request *nrq);
        /**
         * Called after the request being carried out. Could be used for
         * job/resource control; this operation is optional.
         *
         * \param[in,out] policy The policy which is stopping to handle request
         *                       \a nrq
         * \param[in,out] nrq    The request
         *
         * \pre assert_spin_locked(&svcpt->scp_req_lock)
         *
         * \see ptlrpc_nrs_req_stop_nolock()
         */
        void    (*op_req_stop) (struct ptlrpc_nrs_policy *policy,
                                struct ptlrpc_nrs_request *nrq);
        /**
         * Registers the policy's lprocfs interface with a PTLRPC service.
         *
         * \param[in] svc The service
         *
         * \retval 0    success
         * \retval != 0 error
         */
        int     (*op_lprocfs_init) (struct ptlrpc_service *svc);
        /**
         * Unegisters the policy's lprocfs interface with a PTLRPC service.
         *
         * In cases of failed policy registration in
         * \e ptlrpc_nrs_policy_register(), this function may be called for a
         * service which has not registered the policy successfully, so
         * implementations of this method should make sure their operations are
         * safe in such cases.
         *
         * \param[in] svc The service
         */
        void    (*op_lprocfs_fini) (struct ptlrpc_service *svc);
};

/**
 * Policy flags
 */
enum nrs_policy_flags {
        /**
         * Fallback policy, use this flag only on a single supported policy per
         * service. The flag cannot be used on policies that use
         * \e PTLRPC_NRS_FL_REG_EXTERN
         */
        PTLRPC_NRS_FL_FALLBACK          = (1 << 0),
        /**
         * Start policy immediately after registering.
         */
        PTLRPC_NRS_FL_REG_START         = (1 << 1),
        /**
         * This is a policy registering from a module different to the one NRS
         * core ships in (currently ptlrpc).
         */
        PTLRPC_NRS_FL_REG_EXTERN        = (1 << 2),
};

/**
 * NRS queue type.
 *
 * Denotes whether an NRS instance is for handling normal or high-priority
 * RPCs, or whether an operation pertains to one or both of the NRS instances
 * in a service.
 */
enum ptlrpc_nrs_queue_type {
        PTLRPC_NRS_QUEUE_REG    = (1 << 0),
        PTLRPC_NRS_QUEUE_HP     = (1 << 1),
        PTLRPC_NRS_QUEUE_BOTH   = (PTLRPC_NRS_QUEUE_REG | PTLRPC_NRS_QUEUE_HP)
};

/**
 * NRS head
 *
 * A PTLRPC service has at least one NRS head instance for handling normal
 * priority RPCs, and may optionally have a second NRS head instance for
 * handling high-priority RPCs. Each NRS head maintains a list of available
 * policies, of which one and only one policy is acting as the fallback policy,
 * and optionally a different policy may be acting as the primary policy. For
 * all RPCs handled by this NRS head instance, NRS core will first attempt to
 * enqueue the RPC using the primary policy (if any). The fallback policy is
 * used in the following cases:
 * - when there was no primary policy in the
 *   ptlrpc_nrs_pol_state::NRS_POL_STATE_STARTED state at the time the request
 *   was initialized.
 * - when the primary policy that was at the
 *   ptlrpc_nrs_pol_state::PTLRPC_NRS_POL_STATE_STARTED state at the time the
 *   RPC was initialized, denoted it did not wish, or for some other reason was
 *   not able to handle the request, by returning a non-valid NRS resource
 *   reference.
 * - when the primary policy that was at the
 *   ptlrpc_nrs_pol_state::PTLRPC_NRS_POL_STATE_STARTED state at the time the
 *   RPC was initialized, fails later during the request enqueueing stage.
 *
 * \see nrs_resource_get_safe()
 * \see nrs_request_enqueue()
 */
struct ptlrpc_nrs {
        spinlock_t                      nrs_lock;
        /** XXX Possibly replace svcpt->scp_req_lock with another lock here. */
        /**
         * List of registered policies
         */
        struct list_head                        nrs_policy_list;
        /**
         * List of policies with queued requests. Policies that have any
         * outstanding requests are queued here, and this list is queried
         * in a round-robin manner from NRS core when obtaining a request
         * for handling. This ensures that requests from policies that at some
         * point transition away from the
         * ptlrpc_nrs_pol_state::NRS_POL_STATE_STARTED state are drained.
         */
        struct list_head                        nrs_policy_queued;
        /**
         * Service partition for this NRS head
         */
        struct ptlrpc_service_part     *nrs_svcpt;
        /**
         * Primary policy, which is the preferred policy for handling RPCs
         */
        struct ptlrpc_nrs_policy       *nrs_policy_primary;
        /**
         * Fallback policy, which is the backup policy for handling RPCs
         */
        struct ptlrpc_nrs_policy       *nrs_policy_fallback;
        /**
         * This NRS head handles either HP or regular requests
         */
        enum ptlrpc_nrs_queue_type      nrs_queue_type;
        /**
         * # queued requests from all policies in this NRS head
         */
        unsigned long                   nrs_req_queued;
        /**
         * # scheduled requests from all policies in this NRS head
         */
        unsigned long                   nrs_req_started;
        /**
         * # policies on this NRS
         */
        unsigned                        nrs_num_pols;
        /**
         * This NRS head is in progress of starting a policy
         */
        unsigned                        nrs_policy_starting:1;
        /**
         * In progress of shutting down the whole NRS head; used during
         * unregistration
         */
        unsigned                        nrs_stopping:1;
};

#define NRS_POL_NAME_MAX                16

struct ptlrpc_nrs_pol_desc;

/**
 * Service compatibility predicate; this determines whether a policy is adequate
 * for handling RPCs of a particular PTLRPC service.
 *
 * XXX:This should give the same result during policy registration and
 * unregistration, and for all partitions of a service; so the result should not
 * depend on temporal service or other properties, that may influence the
 * result.
 */
typedef bool (*nrs_pol_desc_compat_t) (const struct ptlrpc_service *svc,
                                       const struct ptlrpc_nrs_pol_desc *desc);

struct ptlrpc_nrs_pol_conf {
        /**
         * Human-readable policy name
         */
        char                               nc_name[NRS_POL_NAME_MAX];
        /**
         * NRS operations for this policy
         */
        const struct ptlrpc_nrs_pol_ops   *nc_ops;
        /**
         * Service compatibility predicate
         */
        nrs_pol_desc_compat_t              nc_compat;
        /**
         * Set for policies that support a single ptlrpc service, i.e. ones that
         * have \a pd_compat set to nrs_policy_compat_one(). The variable value
         * depicts the name of the single service that such policies are
         * compatible with.
         */
        const char                        *nc_compat_svc_name;
        /**
         * Owner module for this policy descriptor; policies registering from a
         * different module to the one the NRS framework is held within
         * (currently ptlrpc), should set this field to THIS_MODULE.
         */
        struct module                     *nc_owner;
        /**
         * Policy registration flags; a bitmask of \e nrs_policy_flags
         */
        unsigned                           nc_flags;
};

/**
 * NRS policy registering descriptor
 *
 * Is used to hold a description of a policy that can be passed to NRS core in
 * order to register the policy with NRS heads in different PTLRPC services.
 */
struct ptlrpc_nrs_pol_desc {
        /**
         * Human-readable policy name
         */
        char                                    pd_name[NRS_POL_NAME_MAX];
        /**
         * Link into nrs_core::nrs_policies
         */
        struct list_head                                pd_list;
        /**
         * NRS operations for this policy
         */
        const struct ptlrpc_nrs_pol_ops        *pd_ops;
        /**
         * Service compatibility predicate
         */
        nrs_pol_desc_compat_t                   pd_compat;
        /**
         * Set for policies that are compatible with only one PTLRPC service.
         *
         * \see ptlrpc_nrs_pol_conf::nc_compat_svc_name
         */
        const char                             *pd_compat_svc_name;
        /**
         * Owner module for this policy descriptor.
         *
         * We need to hold a reference to the module whenever we might make use
         * of any of the module's contents, i.e.
         * - If one or more instances of the policy are at a state where they
         *   might be handling a request, i.e.
         *   ptlrpc_nrs_pol_state::NRS_POL_STATE_STARTED or
         *   ptlrpc_nrs_pol_state::NRS_POL_STATE_STOPPING as we will have to
         *   call into the policy's ptlrpc_nrs_pol_ops() handlers. A reference
         *   is taken on the module when
         *   \e ptlrpc_nrs_pol_desc::pd_refs becomes 1, and released when it
         *   becomes 0, so that we hold only one reference to the module maximum
         *   at any time.
         *
         *   We do not need to hold a reference to the module, even though we
         *   might use code and data from the module, in the following cases:
         * - During external policy registration, because this should happen in
         *   the module's init() function, in which case the module is safe from
         *   removal because a reference is being held on the module by the
         *   kernel, and iirc kmod (and I guess module-init-tools also) will
         *   serialize any racing processes properly anyway.
         * - During external policy unregistration, because this should happen
         *   in a module's exit() function, and any attempts to start a policy
         *   instance would need to take a reference on the module, and this is
         *   not possible once we have reached the point where the exit()
         *   handler is called.
         * - During service registration and unregistration, as service setup
         *   and cleanup, and policy registration, unregistration and policy
         *   instance starting, are serialized by \e nrs_core::nrs_mutex, so
         *   as long as users adhere to the convention of registering policies
         *   in init() and unregistering them in module exit() functions, there
         *   should not be a race between these operations.
         * - During any policy-specific lprocfs operations, because a reference
         *   is held by the kernel on a proc entry that has been entered by a
         *   syscall, so as long as proc entries are removed during unregistration time,
         *   then unregistration and lprocfs operations will be properly
         *   serialized.
         */
        struct module                          *pd_owner;
        /**
         * Bitmask of \e nrs_policy_flags
         */
        unsigned                                pd_flags;
        /**
         * # of references on this descriptor
         */
        atomic_t                                pd_refs;
};

/**
 * NRS policy state
 *
 * Policies transition from one state to the other during their lifetime
 */
enum ptlrpc_nrs_pol_state {
        /**
         * Not a valid policy state.
         */
        NRS_POL_STATE_INVALID,
        /**
         * Policies are at this state either at the start of their life, or
         * transition here when the user selects a different policy to act
         * as the primary one.
         */
        NRS_POL_STATE_STOPPED,
        /**
         * Policy is progress of stopping
         */
        NRS_POL_STATE_STOPPING,
        /**
         * Policy is in progress of starting
         */
        NRS_POL_STATE_STARTING,
        /**
         * A policy is in this state in two cases:
         * - it is the fallback policy, which is always in this state.
         * - it has been activated by the user; i.e. it is the primary policy,
         */
        NRS_POL_STATE_STARTED,
};

/**
 * NRS policy information
 *
 * Used for obtaining information for the status of a policy via lprocfs
 */
struct ptlrpc_nrs_pol_info {
        /**
         * Policy name
         */
        char                            pi_name[NRS_POL_NAME_MAX];
        /**
         * Current policy state
         */
        enum ptlrpc_nrs_pol_state       pi_state;
        /**
         * # RPCs enqueued for later dispatching by the policy
         */
        long                            pi_req_queued;
        /**
         * # RPCs started for dispatch by the policy
         */
        long                            pi_req_started;
        /**
         * Is this a fallback policy?
         */
        unsigned                        pi_fallback:1;
};

/**
 * NRS policy
 *
 * There is one instance of this for each policy in each NRS head of each
 * PTLRPC service partition.
 */
struct ptlrpc_nrs_policy {
        /**
         * Linkage into the NRS head's list of policies,
         * ptlrpc_nrs:nrs_policy_list
         */
        struct list_head                        pol_list;
        /**
         * Linkage into the NRS head's list of policies with enqueued
         * requests ptlrpc_nrs:nrs_policy_queued
         */
        struct list_head                        pol_list_queued;
        /**
         * Current state of this policy
         */
        enum ptlrpc_nrs_pol_state       pol_state;
        /**
         * Bitmask of nrs_policy_flags
         */
        unsigned                        pol_flags;
        /**
         * # RPCs enqueued for later dispatching by the policy
         */
        long                            pol_req_queued;
        /**
         * # RPCs started for dispatch by the policy
         */
        long                            pol_req_started;
        /**
         * Usage Reference count taken on the policy instance
         */
        long                            pol_ref;
        /**
         * The NRS head this policy has been created at
         */
        struct ptlrpc_nrs              *pol_nrs;
        /**
         * Private policy data; varies by policy type
         */
        void                           *pol_private;
        /**
         * Policy descriptor for this policy instance.
         */
        struct ptlrpc_nrs_pol_desc     *pol_desc;
};

/**
 * NRS resource
 *
 * Resources are embedded into two types of NRS entities:
 * - Inside NRS policies, in the policy's private data in
 *   ptlrpc_nrs_policy::pol_private
 * - In objects that act as prime-level scheduling entities in different NRS
 *   policies; e.g. on a policy that performs round robin or similar order
 *   scheduling across client NIDs, there would be one NRS resource per unique
 *   client NID. On a policy which performs round robin scheduling across
 *   backend filesystem objects, there would be one resource associated with
 *   each of the backend filesystem objects partaking in the scheduling
 *   performed by the policy.
 *
 * NRS resources share a parent-child relationship, in which resources embedded
 * in policy instances are the parent entities, with all scheduling entities
 * a policy schedules across being the children, thus forming a simple resource
 * hierarchy. This hierarchy may be extended with one or more levels in the
 * future if the ability to have more than one primary policy is added.
 *
 * Upon request initialization, references to the then active NRS policies are
 * taken and used to later handle the dispatching of the request with one of
 * these policies.
 *
 * \see nrs_resource_get_safe()
 * \see ptlrpc_nrs_req_add()
 */
struct ptlrpc_nrs_resource {
        /**
         * This NRS resource's parent; is NULL for resources embedded in NRS
         * policy instances; i.e. those are top-level ones.
         */
        struct ptlrpc_nrs_resource     *res_parent;
        /**
         * The policy associated with this resource.
         */
        struct ptlrpc_nrs_policy       *res_policy;
};

enum {
        NRS_RES_FALLBACK,
        NRS_RES_PRIMARY,
        NRS_RES_MAX
};

/* \name fifo
 *
 * FIFO policy
 *
 * This policy is a logical wrapper around previous, non-NRS functionality.
 * It dispatches RPCs in the same order as they arrive from the network. This
 * policy is currently used as the fallback policy, and the only enabled policy
 * on all NRS heads of all PTLRPC service partitions.
 * @{
 */

/**
 * Private data structure for the FIFO policy
 */
struct nrs_fifo_head {
        /**
         * Resource object for policy instance.
         */
        struct ptlrpc_nrs_resource      fh_res;
        /**
         * List of queued requests.
         */
        struct list_head                        fh_list;
        /**
         * For debugging purposes.
         */
        __u64                           fh_sequence;
};

struct nrs_fifo_req {
        struct list_head                fr_list;
        __u64                   fr_sequence;
};

/** @} fifo */

/**
 * NRS request
 *
 * Instances of this object exist embedded within ptlrpc_request; the main
 * purpose of this object is to hold references to the request's resources
 * for the lifetime of the request, and to hold properties that policies use
 * use for determining the request's scheduling priority.
 */
struct ptlrpc_nrs_request {
        /**
         * The request's resource hierarchy.
         */
        struct ptlrpc_nrs_resource     *nr_res_ptrs[NRS_RES_MAX];
        /**
         * Index into ptlrpc_nrs_request::nr_res_ptrs of the resource of the
         * policy that was used to enqueue the request.
         *
         * \see nrs_request_enqueue()
         */
        unsigned                        nr_res_idx;
        unsigned                        nr_initialized:1;
        unsigned                        nr_enqueued:1;
        unsigned                        nr_started:1;
        unsigned                        nr_finalized:1;

        /**
         * Policy-specific fields, used for determining a request's scheduling
         * priority, and other supporting functionality.
         */
        union {
                /**
                 * Fields for the FIFO policy
                 */
                struct nrs_fifo_req     fifo;
        } nr_u;
        /**
         * Externally-registering policies may want to use this to allocate
         * their own request properties.
         */
        void                           *ext;
};

/** @} nrs */

/**
 * Basic request prioritization operations structure.
 * The whole idea is centered around locks and RPCs that might affect locks.
 * When a lock is contended we try to give priority to RPCs that might lead
 * to fastest release of that lock.
 * Currently only implemented for OSTs only in a way that makes all
 * IO and truncate RPCs that are coming from a locked region where a lock is
 * contended a priority over other requests.
 */
struct ptlrpc_hpreq_ops {
        /**
         * Check if the lock handle of the given lock is the same as
         * taken from the request.
         */
        int  (*hpreq_lock_match)(struct ptlrpc_request *, struct ldlm_lock *);
        /**
         * Check if the request is a high priority one.
         */
        int  (*hpreq_check)(struct ptlrpc_request *);
        /**
         * Called after the request has been handled.
         */
        void (*hpreq_fini)(struct ptlrpc_request *);
};

struct ptlrpc_cli_req {
        /** For bulk requests on client only: bulk descriptor */
        struct ptlrpc_bulk_desc         *cr_bulk;
        /** optional time limit for send attempts */
        long                             cr_delay_limit;
        /** time request was first queued */
        time_t                           cr_queued_time;
        /** request sent timeval */
        struct timespec64                cr_sent_tv;
        /** time for request really sent out */
        time_t                           cr_sent_out;
        /** when req reply unlink must finish. */
        time_t                           cr_reply_deadline;
        /** when req bulk unlink must finish. */
        time_t                           cr_bulk_deadline;
        /** when req unlink must finish. */
        time_t                           cr_req_deadline;
        /** Portal to which this request would be sent */
        short                            cr_req_ptl;
        /** Portal where to wait for reply and where reply would be sent */
        short                            cr_rep_ptl;
        /** request resending number */
        unsigned int                     cr_resend_nr;
        /** What was import generation when this request was sent */
        int                              cr_imp_gen;
        enum lustre_imp_state            cr_send_state;
        /** Per-request waitq introduced by bug 21938 for recovery waiting */
        wait_queue_head_t                cr_set_waitq;
        /** Link item for request set lists */
        struct list_head                 cr_set_chain;
        /** link to waited ctx */
        struct list_head                 cr_ctx_chain;

        /** client's half ctx */
        struct ptlrpc_cli_ctx           *cr_cli_ctx;
        /** Link back to the request set */
        struct ptlrpc_request_set       *cr_set;
        /** outgoing request MD handle */
        lnet_handle_md_t                 cr_req_md_h;
        /** request-out callback parameter */
        struct ptlrpc_cb_id              cr_req_cbid;
        /** incoming reply MD handle */
        lnet_handle_md_t                 cr_reply_md_h;
        wait_queue_head_t                cr_reply_waitq;
        /** reply callback parameter */
        struct ptlrpc_cb_id              cr_reply_cbid;
        /** Async completion handler, called when reply is received */
        ptlrpc_interpterer_t             cr_reply_interp;
        /** Async completion context */
        union ptlrpc_async_args          cr_async_args;
        /** Opaq data for replay and commit callbacks. */
        void                            *cr_cb_data;
        /**
         * Commit callback, called when request is committed and about to be
         * freed.
         */
        void (*cr_commit_cb)(struct ptlrpc_request *);
        /** Replay callback, called after request is replayed at recovery */
        void (*cr_replay_cb)(struct ptlrpc_request *);
};

/** client request member alias */
/* NB: these alias should NOT be used by any new code, instead they should
 * be removed step by step to avoid potential abuse
 */
#define rq_bulk                 rq_cli.cr_bulk
#define rq_delay_limit          rq_cli.cr_delay_limit
#define rq_queued_time          rq_cli.cr_queued_time
#define rq_sent_tv              rq_cli.cr_sent_tv
#define rq_real_sent            rq_cli.cr_sent_out
#define rq_reply_deadline       rq_cli.cr_reply_deadline
#define rq_bulk_deadline        rq_cli.cr_bulk_deadline
#define rq_req_deadline         rq_cli.cr_req_deadline
#define rq_nr_resend            rq_cli.cr_resend_nr
#define rq_request_portal       rq_cli.cr_req_ptl
#define rq_reply_portal         rq_cli.cr_rep_ptl
#define rq_import_generation    rq_cli.cr_imp_gen
#define rq_send_state           rq_cli.cr_send_state
#define rq_set_chain            rq_cli.cr_set_chain
#define rq_ctx_chain            rq_cli.cr_ctx_chain
#define rq_set                  rq_cli.cr_set
#define rq_set_waitq            rq_cli.cr_set_waitq
#define rq_cli_ctx              rq_cli.cr_cli_ctx
#define rq_req_md_h             rq_cli.cr_req_md_h
#define rq_req_cbid             rq_cli.cr_req_cbid
#define rq_reply_md_h           rq_cli.cr_reply_md_h
#define rq_reply_waitq          rq_cli.cr_reply_waitq
#define rq_reply_cbid           rq_cli.cr_reply_cbid
#define rq_interpret_reply      rq_cli.cr_reply_interp
#define rq_async_args           rq_cli.cr_async_args
#define rq_cb_data              rq_cli.cr_cb_data
#define rq_commit_cb            rq_cli.cr_commit_cb
#define rq_replay_cb            rq_cli.cr_replay_cb

struct ptlrpc_srv_req {
        /** initial thread servicing this request */
        struct ptlrpc_thread            *sr_svc_thread;
        /**
         * Server side list of incoming unserved requests sorted by arrival
         * time.  Traversed from time to time to notice about to expire
         * requests and sent back "early replies" to clients to let them
         * know server is alive and well, just very busy to service their
         * requests in time
         */
        struct list_head                sr_timed_list;
        /** server-side per-export list */
        struct list_head                sr_exp_list;
        /** server-side history, used for debuging purposes. */
        struct list_head                sr_hist_list;
        /** history sequence # */
        __u64                           sr_hist_seq;
        /** the index of service's srv_at_array into which request is linked */
        time_t                          sr_at_index;
        /** authed uid */
        uid_t                           sr_auth_uid;
        /** authed uid mapped to */
        uid_t                           sr_auth_mapped_uid;
        /** RPC is generated from what part of Lustre */
        enum lustre_sec_part            sr_sp_from;
        /** request session context */
        struct lu_context               sr_ses;
        /** \addtogroup  nrs
         * @{
         */
        /** stub for NRS request */
        struct ptlrpc_nrs_request       sr_nrq;
        /** @} nrs */
        /** request arrival time */
        struct timespec64               sr_arrival_time;
        /** server's half ctx */
        struct ptlrpc_svc_ctx           *sr_svc_ctx;
        /** (server side), pointed directly into req buffer */
        struct ptlrpc_user_desc         *sr_user_desc;
        /** separated reply state */
        struct ptlrpc_reply_state       *sr_reply_state;
        /** server-side hp handlers */
        struct ptlrpc_hpreq_ops         *sr_ops;
        /** incoming request buffer */
        struct ptlrpc_request_buffer_desc *sr_rqbd;
};

/** server request member alias */
/* NB: these alias should NOT be used by any new code, instead they should
 * be removed step by step to avoid potential abuse
 */
#define rq_svc_thread           rq_srv.sr_svc_thread
#define rq_timed_list           rq_srv.sr_timed_list
#define rq_exp_list             rq_srv.sr_exp_list
#define rq_history_list         rq_srv.sr_hist_list
#define rq_history_seq          rq_srv.sr_hist_seq
#define rq_at_index             rq_srv.sr_at_index
#define rq_auth_uid             rq_srv.sr_auth_uid
#define rq_auth_mapped_uid      rq_srv.sr_auth_mapped_uid
#define rq_sp_from              rq_srv.sr_sp_from
#define rq_session              rq_srv.sr_ses
#define rq_nrq                  rq_srv.sr_nrq
#define rq_arrival_time         rq_srv.sr_arrival_time
#define rq_reply_state          rq_srv.sr_reply_state
#define rq_svc_ctx              rq_srv.sr_svc_ctx
#define rq_user_desc            rq_srv.sr_user_desc
#define rq_ops                  rq_srv.sr_ops
#define rq_rqbd                 rq_srv.sr_rqbd

/**
 * Represents remote procedure call.
 *
 * This is a staple structure used by everybody wanting to send a request
 * in Lustre.
 */
struct ptlrpc_request {
        /* Request type: one of PTL_RPC_MSG_* */
        int                              rq_type;
        /** Result of request processing */
        int                              rq_status;
        /**
         * Linkage item through which this request is included into
         * sending/delayed lists on client and into rqbd list on server
         */
        struct list_head                 rq_list;
        /** Lock to protect request flags and some other important bits, like
         * rq_list
         */
        spinlock_t rq_lock;
        /** client-side flags are serialized by rq_lock @{ */
        unsigned int rq_intr:1, rq_replied:1, rq_err:1,
                rq_timedout:1, rq_resend:1, rq_restart:1,
                /**
                 * when ->rq_replay is set, request is kept by the client even
                 * after server commits corresponding transaction. This is
                 * used for operations that require sequence of multiple
                 * requests to be replayed. The only example currently is file
                 * open/close. When last request in such a sequence is
                 * committed, ->rq_replay is cleared on all requests in the
                 * sequence.
                 */
                rq_replay:1,
                rq_no_resend:1, rq_waiting:1, rq_receiving_reply:1,
                rq_no_delay:1, rq_net_err:1, rq_wait_ctx:1,
                rq_early:1,
                rq_req_unlinked:1,      /* unlinked request buffer from lnet */
                rq_reply_unlinked:1,    /* unlinked reply buffer from lnet */
                rq_memalloc:1,      /* req originated from "kswapd" */
                rq_committed:1,
                rq_reply_truncated:1,
                /** whether the "rq_set" is a valid one */
                rq_invalid_rqset:1,
                rq_generation_set:1,
                /** do not resend request on -EINPROGRESS */
                rq_no_retry_einprogress:1,
                /* allow the req to be sent if the import is in recovery
                 * status
                 */
                rq_allow_replay:1,
                /* bulk request, sent to server, but uncommitted */
                rq_unstable:1;
        /** @} */

        /** server-side flags @{ */
        unsigned int
                rq_hp:1,                /**< high priority RPC */
                rq_at_linked:1,         /**< link into service's srv_at_array */
                rq_packed_final:1;      /**< packed final reply */
        /** @} */

        /** one of RQ_PHASE_* */
        enum rq_phase                   rq_phase;
        /** one of RQ_PHASE_* to be used next */
        enum rq_phase                   rq_next_phase;
        /**
         * client-side refcount for SENT race, server-side refcount
         * for multiple replies
         */
        atomic_t                        rq_refcount;
        /**
         * client-side:
         * !rq_truncate : # reply bytes actually received,
         *  rq_truncate : required repbuf_len for resend
         */
        int rq_nob_received;
        /** Request length */
        int rq_reqlen;
        /** Reply length */
        int rq_replen;
        /** Pool if request is from preallocated list */
        struct ptlrpc_request_pool     *rq_pool;
        /** Request message - what client sent */
        struct lustre_msg *rq_reqmsg;
        /** Reply message - server response */
        struct lustre_msg *rq_repmsg;
        /** Transaction number */
        __u64 rq_transno;
        /** xid */
        __u64 rq_xid;
        /**
         * List item to for replay list. Not yet committed requests get linked
         * there.
         * Also see \a rq_replay comment above.
         * It's also link chain on obd_export::exp_req_replay_queue
         */
        struct list_head rq_replay_list;
        /** non-shared members for client & server request*/
        union {
                struct ptlrpc_cli_req    rq_cli;
                struct ptlrpc_srv_req    rq_srv;
        };
        /**
         * security and encryption data
         * @{
         */
        /** description of flavors for client & server */
        struct sptlrpc_flavor           rq_flvr;

        /* client/server security flags */
        unsigned int
                                 rq_ctx_init:1,      /* context initiation */
                                 rq_ctx_fini:1,      /* context destroy */
                                 rq_bulk_read:1,     /* request bulk read */
                                 rq_bulk_write:1,    /* request bulk write */
                                 /* server authentication flags */
                                 rq_auth_gss:1,      /* authenticated by gss */
                                 rq_auth_usr_root:1, /* authed as root */
                                 rq_auth_usr_mdt:1,  /* authed as mdt */
                                 rq_auth_usr_ost:1,  /* authed as ost */
                                 /* security tfm flags */
                                 rq_pack_udesc:1,
                                 rq_pack_bulk:1,
                                 /* doesn't expect reply FIXME */
                                 rq_no_reply:1,
                                 rq_pill_init:1, /* pill initialized */
                                 rq_srv_req:1; /* server request */

        /** various buffer pointers */
        struct lustre_msg       *rq_reqbuf;     /**< req wrapper */
        char                    *rq_repbuf;     /**< rep buffer */
        struct lustre_msg       *rq_repdata;    /**< rep wrapper msg */
        /** only in priv mode */
        struct lustre_msg       *rq_clrbuf;
        int                   rq_reqbuf_len;  /* req wrapper buf len */
        int                   rq_reqdata_len; /* req wrapper msg len */
        int                   rq_repbuf_len;  /* rep buffer len */
        int                   rq_repdata_len; /* rep wrapper msg len */
        int                   rq_clrbuf_len;  /* only in priv mode */
        int                   rq_clrdata_len; /* only in priv mode */

        /** early replies go to offset 0, regular replies go after that */
        unsigned int         rq_reply_off;

        /** @} */

        /** Fields that help to see if request and reply were swabbed or not */
        __u32 rq_req_swab_mask;
        __u32 rq_rep_swab_mask;

        /** how many early replies (for stats) */
        int rq_early_count;

        /** Server-side, export on which request was received */
        struct obd_export               *rq_export;
        /** import where request is being sent */
        struct obd_import               *rq_import;
        /** our LNet NID */
        lnet_nid_t         rq_self;
        /** Peer description (the other side) */
        lnet_process_id_t    rq_peer;
        /**
         * service time estimate (secs)
         * If the request is not served by this time, it is marked as timed out.
         */
        int                     rq_timeout;
        /**
         * when request/reply sent (secs), or time when request should be sent
         */
        time64_t rq_sent;
        /** when request must finish. */
        time64_t                  rq_deadline;
        /** request format description */
        struct req_capsule        rq_pill;
};

/**
 * Call completion handler for rpc if any, return it's status or original
 * rc if there was no handler defined for this request.
 */
static inline int ptlrpc_req_interpret(const struct lu_env *env,
                                       struct ptlrpc_request *req, int rc)
{
        if (req->rq_interpret_reply) {
                req->rq_status = req->rq_interpret_reply(env, req,
                                                         &req->rq_async_args,
                                                         rc);
                return req->rq_status;
        }
        return rc;
}

/*
 * Can the request be moved from the regular NRS head to the high-priority NRS
 * head (of the same PTLRPC service partition), if any?
 *
 * For a reliable result, this should be checked under svcpt->scp_req lock.
 */
static inline bool ptlrpc_nrs_req_can_move(struct ptlrpc_request *req)
{
        struct ptlrpc_nrs_request *nrq = &req->rq_nrq;

        /**
         * LU-898: Check ptlrpc_nrs_request::nr_enqueued to make sure the
         * request has been enqueued first, and ptlrpc_nrs_request::nr_started
         * to make sure it has not been scheduled yet (analogous to previous
         * (non-NRS) checking of !list_empty(&ptlrpc_request::rq_list).
         */
        return nrq->nr_enqueued && !nrq->nr_started && !req->rq_hp;
}

/** @} nrs */

/**
 * Returns 1 if request buffer at offset \a index was already swabbed
 */
static inline int lustre_req_swabbed(struct ptlrpc_request *req, int index)
{
        LASSERT(index < sizeof(req->rq_req_swab_mask) * 8);
        return req->rq_req_swab_mask & (1 << index);
}

/**
 * Returns 1 if request reply buffer at offset \a index was already swabbed
 */
static inline int lustre_rep_swabbed(struct ptlrpc_request *req, int index)
{
        LASSERT(index < sizeof(req->rq_rep_swab_mask) * 8);
        return req->rq_rep_swab_mask & (1 << index);
}

/**
 * Returns 1 if request needs to be swabbed into local cpu byteorder
 */
static inline int ptlrpc_req_need_swab(struct ptlrpc_request *req)
{
        return lustre_req_swabbed(req, MSG_PTLRPC_HEADER_OFF);
}

/**
 * Returns 1 if request reply needs to be swabbed into local cpu byteorder
 */
static inline int ptlrpc_rep_need_swab(struct ptlrpc_request *req)
{
        return lustre_rep_swabbed(req, MSG_PTLRPC_HEADER_OFF);
}

/**
 * Mark request buffer at offset \a index that it was already swabbed
 */
static inline void lustre_set_req_swabbed(struct ptlrpc_request *req, int index)
{
        LASSERT(index < sizeof(req->rq_req_swab_mask) * 8);
        LASSERT((req->rq_req_swab_mask & (1 << index)) == 0);
        req->rq_req_swab_mask |= 1 << index;
}

/**
 * Mark request reply buffer at offset \a index that it was already swabbed
 */
static inline void lustre_set_rep_swabbed(struct ptlrpc_request *req, int index)
{
        LASSERT(index < sizeof(req->rq_rep_swab_mask) * 8);
        LASSERT((req->rq_rep_swab_mask & (1 << index)) == 0);
        req->rq_rep_swab_mask |= 1 << index;
}

/**
 * Convert numerical request phase value \a phase into text string description
 */
static inline const char *
ptlrpc_phase2str(enum rq_phase phase)
{
        switch (phase) {
        case RQ_PHASE_NEW:
                return "New";
        case RQ_PHASE_RPC:
                return "Rpc";
        case RQ_PHASE_BULK:
                return "Bulk";
        case RQ_PHASE_INTERPRET:
                return "Interpret";
        case RQ_PHASE_COMPLETE:
                return "Complete";
        case RQ_PHASE_UNREG_RPC:
                return "UnregRPC";
        case RQ_PHASE_UNREG_BULK:
                return "UnregBULK";
        default:
                return "?Phase?";
        }
}

/**
 * Convert numerical request phase of the request \a req into text stringi
 * description
 */
static inline const char *
ptlrpc_rqphase2str(struct ptlrpc_request *req)
{
        return ptlrpc_phase2str(req->rq_phase);
}

/**
 * Debugging functions and helpers to print request structure into debug log
 * @{
 */
/* Spare the preprocessor, spoil the bugs. */
#define FLAG(field, str) (field ? str : "")

/** Convert bit flags into a string */
#define DEBUG_REQ_FLAGS(req)                                                \
        ptlrpc_rqphase2str(req),                                                \
        FLAG(req->rq_intr, "I"), FLAG(req->rq_replied, "R"),                \
        FLAG(req->rq_err, "E"), FLAG(req->rq_net_err, "e"),                 \
        FLAG(req->rq_timedout, "X") /* eXpired */, FLAG(req->rq_resend, "S"),   \
        FLAG(req->rq_restart, "T"), FLAG(req->rq_replay, "P"),            \
        FLAG(req->rq_no_resend, "N"),                                      \
        FLAG(req->rq_waiting, "W"),                                          \
        FLAG(req->rq_wait_ctx, "C"), FLAG(req->rq_hp, "H"),                  \
        FLAG(req->rq_committed, "M")

#define REQ_FLAGS_FMT "%s:%s%s%s%s%s%s%s%s%s%s%s%s%s"

void _debug_req(struct ptlrpc_request *req,
                struct libcfs_debug_msg_data *data, const char *fmt, ...)
        __printf(3, 4);

/**
 * Helper that decides if we need to print request according to current debug
 * level settings
 */
#define debug_req(msgdata, mask, cdls, req, fmt, a...)                  \
do {                                                                      \
        CFS_CHECK_STACK(msgdata, mask, cdls);                            \
                                                                              \
        if (((mask) & D_CANTMASK) != 0 ||                                    \
            ((libcfs_debug & (mask)) != 0 &&                              \
             (libcfs_subsystem_debug & DEBUG_SUBSYSTEM) != 0))          \
                _debug_req((req), msgdata, fmt, ##a);                    \
} while (0)

/**
 * This is the debug print function you need to use to print request structure
 * content into lustre debug log.
 * for most callers (level is a constant) this is resolved at compile time
 */
#define DEBUG_REQ(level, req, fmt, args...)                                \
do {                                                                      \
        if ((level) & (D_ERROR | D_WARNING)) {                          \
                static struct cfs_debug_limit_state cdls;                         \
                LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, level, &cdls);          \
                debug_req(&msgdata, level, &cdls, req, "@@@ "fmt" ", ## args);\
        } else {                                                              \
                LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, level, NULL);            \
                debug_req(&msgdata, level, NULL, req, "@@@ "fmt" ", ## args); \
        }                                                                    \
} while (0)
/** @} */

/**
 * Structure that defines a single page of a bulk transfer
 */
struct ptlrpc_bulk_page {
        /** Linkage to list of pages in a bulk */
        struct list_head       bp_link;
        /**
         * Number of bytes in a page to transfer starting from \a bp_pageoffset
         */
        int           bp_buflen;
        /** offset within a page */
        int           bp_pageoffset;
        /** The page itself */
        struct page     *bp_page;
};

#define BULK_GET_SOURCE   0
#define BULK_PUT_SINK     1
#define BULK_GET_SINK     2
#define BULK_PUT_SOURCE   3

/**
 * Definition of bulk descriptor.
 * Bulks are special "Two phase" RPCs where initial request message
 * is sent first and it is followed bt a transfer (o receiving) of a large
 * amount of data to be settled into pages referenced from the bulk descriptors.
 * Bulks transfers (the actual data following the small requests) are done
 * on separate LNet portals.
 * In lustre we use bulk transfers for READ and WRITE transfers from/to OSTs.
 *  Another user is readpage for MDT.
 */
struct ptlrpc_bulk_desc {
        /** completed with failure */
        unsigned long bd_failure:1;
        /** {put,get}{source,sink} */
        unsigned long bd_type:2;
        /** client side */
        unsigned long bd_registered:1;
        /** For serialization with callback */
        spinlock_t bd_lock;
        /** Import generation when request for this bulk was sent */
        int bd_import_generation;
        /** LNet portal for this bulk */
        __u32 bd_portal;
        /** Server side - export this bulk created for */
        struct obd_export *bd_export;
        /** Client side - import this bulk was sent on */
        struct obd_import *bd_import;
        /** Back pointer to the request */
        struct ptlrpc_request *bd_req;
        wait_queue_head_t           bd_waitq;   /* server side only WQ */
        int                 bd_iov_count;    /* # entries in bd_iov */
        int                 bd_max_iov;      /* allocated size of bd_iov */
        int                 bd_nob;       /* # bytes covered */
        int                 bd_nob_transferred; /* # bytes GOT/PUT */

        __u64             bd_last_xid;

        struct ptlrpc_cb_id    bd_cbid;  /* network callback info */
        lnet_nid_t           bd_sender;       /* stash event::sender */
        int                     bd_md_count;    /* # valid entries in bd_mds */
        int                     bd_md_max_brw;  /* max entries in bd_mds */
        /** array of associated MDs */
        lnet_handle_md_t        bd_mds[PTLRPC_BULK_OPS_COUNT];

        /*
         * encrypt iov, size is either 0 or bd_iov_count.
         */
        lnet_kiov_t        *bd_enc_iov;

        lnet_kiov_t         bd_iov[0];
};

enum {
        SVC_STOPPED     = 1 << 0,
        SVC_STOPPING    = 1 << 1,
        SVC_STARTING    = 1 << 2,
        SVC_RUNNING     = 1 << 3,
        SVC_EVENT       = 1 << 4,
        SVC_SIGNAL      = 1 << 5,
};

#define PTLRPC_THR_NAME_LEN             32
/**
 * Definition of server service thread structure
 */
struct ptlrpc_thread {
        /**
         * List of active threads in svc->srv_threads
         */
        struct list_head t_link;
        /**
         * thread-private data (preallocated memory)
         */
        void *t_data;
        __u32 t_flags;
        /**
         * service thread index, from ptlrpc_start_threads
         */
        unsigned int t_id;
        /**
         * service thread pid
         */
        pid_t t_pid;
        /**
         * put watchdog in the structure per thread b=14840
         *
         * Lustre watchdog is removed for client in the hope
         * of a generic watchdog can be merged in kernel.
         * When that happens, we should add below back.
         *
         * struct lc_watchdog *t_watchdog;
         */
        /**
         * the svc this thread belonged to b=18582
         */
        struct ptlrpc_service_part      *t_svcpt;
        wait_queue_head_t                       t_ctl_waitq;
        struct lu_env                   *t_env;
        char                            t_name[PTLRPC_THR_NAME_LEN];
};

static inline int thread_is_init(struct ptlrpc_thread *thread)
{
        return thread->t_flags == 0;
}

static inline int thread_is_stopped(struct ptlrpc_thread *thread)
{
        return !!(thread->t_flags & SVC_STOPPED);
}

static inline int thread_is_stopping(struct ptlrpc_thread *thread)
{
        return !!(thread->t_flags & SVC_STOPPING);
}

static inline int thread_is_starting(struct ptlrpc_thread *thread)
{
        return !!(thread->t_flags & SVC_STARTING);
}

static inline int thread_is_running(struct ptlrpc_thread *thread)
{
        return !!(thread->t_flags & SVC_RUNNING);
}

static inline int thread_is_event(struct ptlrpc_thread *thread)
{
        return !!(thread->t_flags & SVC_EVENT);
}

static inline int thread_is_signal(struct ptlrpc_thread *thread)
{
        return !!(thread->t_flags & SVC_SIGNAL);
}

static inline void thread_clear_flags(struct ptlrpc_thread *thread, __u32 flags)
{
        thread->t_flags &= ~flags;
}

static inline void thread_set_flags(struct ptlrpc_thread *thread, __u32 flags)
{
        thread->t_flags = flags;
}

static inline void thread_add_flags(struct ptlrpc_thread *thread, __u32 flags)
{
        thread->t_flags |= flags;
}

static inline int thread_test_and_clear_flags(struct ptlrpc_thread *thread,
                                              __u32 flags)
{
        if (thread->t_flags & flags) {
                thread->t_flags &= ~flags;
                return 1;
        }
        return 0;
}

/**
 * Request buffer descriptor structure.
 * This is a structure that contains one posted request buffer for service.
 * Once data land into a buffer, event callback creates actual request and
 * notifies wakes one of the service threads to process new incoming request.
 * More than one request can fit into the buffer.
 */
struct ptlrpc_request_buffer_desc {
        /** Link item for rqbds on a service */
        struct list_head             rqbd_list;
        /** History of requests for this buffer */
        struct list_head             rqbd_reqs;
        /** Back pointer to service for which this buffer is registered */
        struct ptlrpc_service_part *rqbd_svcpt;
        /** LNet descriptor */
        lnet_handle_md_t       rqbd_md_h;
        int                 rqbd_refcount;
        /** The buffer itself */
        char              *rqbd_buffer;
        struct ptlrpc_cb_id    rqbd_cbid;
        /**
         * This "embedded" request structure is only used for the
         * last request to fit into the buffer
         */
        struct ptlrpc_request  rqbd_req;
};

typedef int  (*svc_handler_t)(struct ptlrpc_request *req);

struct ptlrpc_service_ops {
        /**
         * if non-NULL called during thread creation (ptlrpc_start_thread())
         * to initialize service specific per-thread state.
         */
        int             (*so_thr_init)(struct ptlrpc_thread *thr);
        /**
         * if non-NULL called during thread shutdown (ptlrpc_main()) to
         * destruct state created by ->srv_init().
         */
        void            (*so_thr_done)(struct ptlrpc_thread *thr);
        /**
         * Handler function for incoming requests for this service
         */
        int             (*so_req_handler)(struct ptlrpc_request *req);
        /**
         * function to determine priority of the request, it's called
         * on every new request
         */
        int             (*so_hpreq_handler)(struct ptlrpc_request *);
        /**
         * service-specific print fn
         */
        void            (*so_req_printer)(void *, struct ptlrpc_request *);
};

#ifndef __cfs_cacheline_aligned
/* NB: put it here for reducing patche dependence */
# define __cfs_cacheline_aligned
#endif

/**
 * How many high priority requests to serve before serving one normal
 * priority request
 */
#define PTLRPC_SVC_HP_RATIO 10

/**
 * Definition of PortalRPC service.
 * The service is listening on a particular portal (like tcp port)
 * and perform actions for a specific server like IO service for OST
 * or general metadata service for MDS.
 */
struct ptlrpc_service {
        /** serialize sysfs operations */
        spinlock_t                      srv_lock;
        /** most often accessed fields */
        /** chain thru all services */
        struct list_head                      srv_list;
        /** service operations table */
        struct ptlrpc_service_ops       srv_ops;
        /** only statically allocated strings here; we don't clean them */
        char                       *srv_name;
        /** only statically allocated strings here; we don't clean them */
        char                       *srv_thread_name;
        /** service thread list */
        struct list_head                      srv_threads;
        /** threads # should be created for each partition on initializing */
        int                             srv_nthrs_cpt_init;
        /** limit of threads number for each partition */
        int                             srv_nthrs_cpt_limit;
        /** Root of debugfs dir tree for this service */
        struct dentry              *srv_debugfs_entry;
        /** Pointer to statistic data for this service */
        struct lprocfs_stats       *srv_stats;
        /** # hp per lp reqs to handle */
        int                          srv_hpreq_ratio;
        /** biggest request to receive */
        int                          srv_max_req_size;
        /** biggest reply to send */
        int                          srv_max_reply_size;
        /** size of individual buffers */
        int                          srv_buf_size;
        /** # buffers to allocate in 1 group */
        int                          srv_nbuf_per_group;
        /** Local portal on which to receive requests */
        __u32                      srv_req_portal;
        /** Portal on the client to send replies to */
        __u32                      srv_rep_portal;
        /**
         * Tags for lu_context associated with this thread, see struct
         * lu_context.
         */
        __u32                      srv_ctx_tags;
        /** soft watchdog timeout multiplier */
        int                          srv_watchdog_factor;
        /** under unregister_service */
        unsigned                        srv_is_stopping:1;

        /** max # request buffers in history per partition */
        int                             srv_hist_nrqbds_cpt_max;
        /** number of CPTs this service bound on */
        int                             srv_ncpts;
        /** CPTs array this service bound on */
        __u32                           *srv_cpts;
        /** 2^srv_cptab_bits >= cfs_cpt_numbert(srv_cptable) */
        int                             srv_cpt_bits;
        /** CPT table this service is running over */
        struct cfs_cpt_table            *srv_cptable;

        /* sysfs object */
        struct kobject                   srv_kobj;
        struct completion                srv_kobj_unregister;
        /**
         * partition data for ptlrpc service
         */
        struct ptlrpc_service_part      *srv_parts[0];
};

/**
 * Definition of PortalRPC service partition data.
 * Although a service only has one instance of it right now, but we
 * will have multiple instances very soon (instance per CPT).
 *
 * it has four locks:
 * \a scp_lock
 *    serialize operations on rqbd and requests waiting for preprocess
 * \a scp_req_lock
 *    serialize operations active requests sent to this portal
 * \a scp_at_lock
 *    serialize adaptive timeout stuff
 * \a scp_rep_lock
 *    serialize operations on RS list (reply states)
 *
 * We don't have any use-case to take two or more locks at the same time
 * for now, so there is no lock order issue.
 */
struct ptlrpc_service_part {
        /** back reference to owner */
        struct ptlrpc_service           *scp_service __cfs_cacheline_aligned;
        /* CPT id, reserved */
        int                             scp_cpt;
        /** always increasing number */
        int                             scp_thr_nextid;
        /** # of starting threads */
        int                             scp_nthrs_starting;
        /** # of stopping threads, reserved for shrinking threads */
        int                             scp_nthrs_stopping;
        /** # running threads */
        int                             scp_nthrs_running;
        /** service threads list */
        struct list_head                        scp_threads;

        /**
         * serialize the following fields, used for protecting
         * rqbd list and incoming requests waiting for preprocess,
         * threads starting & stopping are also protected by this lock.
         */
        spinlock_t scp_lock __cfs_cacheline_aligned;
        /** total # req buffer descs allocated */
        int                             scp_nrqbds_total;
        /** # posted request buffers for receiving */
        int                             scp_nrqbds_posted;
        /** in progress of allocating rqbd */
        int                             scp_rqbd_allocating;
        /** # incoming reqs */
        int                             scp_nreqs_incoming;
        /** request buffers to be reposted */
        struct list_head                        scp_rqbd_idle;
        /** req buffers receiving */
        struct list_head                        scp_rqbd_posted;
        /** incoming reqs */
        struct list_head                        scp_req_incoming;
        /** timeout before re-posting reqs, in tick */
        long                    scp_rqbd_timeout;
        /**
         * all threads sleep on this. This wait-queue is signalled when new
         * incoming request arrives and when difficult reply has to be handled.
         */
        wait_queue_head_t                       scp_waitq;

        /** request history */
        struct list_head                        scp_hist_reqs;
        /** request buffer history */
        struct list_head                        scp_hist_rqbds;
        /** # request buffers in history */
        int                             scp_hist_nrqbds;
        /** sequence number for request */
        __u64                           scp_hist_seq;
        /** highest seq culled from history */
        __u64                           scp_hist_seq_culled;

        /**
         * serialize the following fields, used for processing requests
         * sent to this portal
         */
        spinlock_t                      scp_req_lock __cfs_cacheline_aligned;
        /** # reqs in either of the NRS heads below */
        /** # reqs being served */
        int                             scp_nreqs_active;
        /** # HPreqs being served */
        int                             scp_nhreqs_active;
        /** # hp requests handled */
        int                             scp_hreq_count;

        /** NRS head for regular requests */
        struct ptlrpc_nrs               scp_nrs_reg;
        /** NRS head for HP requests; this is only valid for services that can
         *  handle HP requests
         */
        struct ptlrpc_nrs              *scp_nrs_hp;

        /** AT stuff */
        /** @{ */
        /**
         * serialize the following fields, used for changes on
         * adaptive timeout
         */
        spinlock_t                      scp_at_lock __cfs_cacheline_aligned;
        /** estimated rpc service time */
        struct adaptive_timeout         scp_at_estimate;
        /** reqs waiting for replies */
        struct ptlrpc_at_array          scp_at_array;
        /** early reply timer */
        struct timer_list               scp_at_timer;
        /** debug */
        unsigned long                   scp_at_checktime;
        /** check early replies */
        unsigned                        scp_at_check;
        /** @} */

        /**
         * serialize the following fields, used for processing
         * replies for this portal
         */
        spinlock_t                      scp_rep_lock __cfs_cacheline_aligned;
        /** all the active replies */
        struct list_head                        scp_rep_active;
        /** List of free reply_states */
        struct list_head                        scp_rep_idle;
        /** waitq to run, when adding stuff to srv_free_rs_list */
        wait_queue_head_t                       scp_rep_waitq;
        /** # 'difficult' replies */
        atomic_t                        scp_nreps_difficult;
};

#define ptlrpc_service_for_each_part(part, i, svc)                      \
        for (i = 0;                                                     \
             i < (svc)->srv_ncpts &&                                    \
             (svc)->srv_parts &&                                        \
             ((part) = (svc)->srv_parts[i]); i++)

/**
 * Declaration of ptlrpcd control structure
 */
struct ptlrpcd_ctl {
        /**
         * Ptlrpc thread control flags (LIOD_START, LIOD_STOP, LIOD_FORCE)
         */
        unsigned long                   pc_flags;
        /**
         * Thread lock protecting structure fields.
         */
        spinlock_t                      pc_lock;
        /**
         * Start completion.
         */
        struct completion               pc_starting;
        /**
         * Stop completion.
         */
        struct completion               pc_finishing;
        /**
         * Thread requests set.
         */
        struct ptlrpc_request_set  *pc_set;
        /**
         * Thread name used in kthread_run()
         */
        char                    pc_name[16];
        /**
         * Environment for request interpreters to run in.
         */
        struct lu_env          pc_env;
        /**
         * CPT the thread is bound on.
         */
        int                             pc_cpt;
        /**
         * Index of ptlrpcd thread in the array.
         */
        int                             pc_index;
        /**
         * Pointer to the array of partners' ptlrpcd_ctl structure.
         */
        struct ptlrpcd_ctl      **pc_partners;
        /**
         * Number of the ptlrpcd's partners.
         */
        int                             pc_npartners;
        /**
         * Record the partner index to be processed next.
         */
        int                      pc_cursor;
        /**
         * Error code if the thread failed to fully start.
         */
        int                             pc_error;
};

/* Bits for pc_flags */
enum ptlrpcd_ctl_flags {
        /**
         * Ptlrpc thread start flag.
         */
        LIOD_START       = 1 << 0,
        /**
         * Ptlrpc thread stop flag.
         */
        LIOD_STOP       = 1 << 1,
        /**
         * Ptlrpc thread force flag (only stop force so far).
         * This will cause aborting any inflight rpcs handled
         * by thread if LIOD_STOP is specified.
         */
        LIOD_FORCE       = 1 << 2,
        /**
         * This is a recovery ptlrpc thread.
         */
        LIOD_RECOVERY    = 1 << 3,
};

/**
 * \addtogroup nrs
 * @{
 *
 * Service compatibility function; the policy is compatible with all services.
 *
 * \param[in] svc  The service the policy is attempting to register with.
 * \param[in] desc The policy descriptor
 *
 * \retval true The policy is compatible with the service
 *
 * \see ptlrpc_nrs_pol_desc::pd_compat()
 */
static inline bool nrs_policy_compat_all(const struct ptlrpc_service *svc,
                                         const struct ptlrpc_nrs_pol_desc *desc)
{
        return true;
}

/**
 * Service compatibility function; the policy is compatible with only a specific
 * service which is identified by its human-readable name at
 * ptlrpc_service::srv_name.
 *
 * \param[in] svc  The service the policy is attempting to register with.
 * \param[in] desc The policy descriptor
 *
 * \retval false The policy is not compatible with the service
 * \retval true  The policy is compatible with the service
 *
 * \see ptlrpc_nrs_pol_desc::pd_compat()
 */
static inline bool nrs_policy_compat_one(const struct ptlrpc_service *svc,
                                         const struct ptlrpc_nrs_pol_desc *desc)
{
        return strcmp(svc->srv_name, desc->pd_compat_svc_name) == 0;
}

/** @} nrs */

/* ptlrpc/events.c */
extern lnet_handle_eq_t ptlrpc_eq_h;
int ptlrpc_uuid_to_peer(struct obd_uuid *uuid,
                        lnet_process_id_t *peer, lnet_nid_t *self);
/**
 * These callbacks are invoked by LNet when something happened to
 * underlying buffer
 * @{
 */
void request_out_callback(lnet_event_t *ev);
void reply_in_callback(lnet_event_t *ev);
void client_bulk_callback(lnet_event_t *ev);
void request_in_callback(lnet_event_t *ev);
void reply_out_callback(lnet_event_t *ev);
/** @} */

/* ptlrpc/connection.c */
struct ptlrpc_connection *ptlrpc_connection_get(lnet_process_id_t peer,
                                                lnet_nid_t self,
                                                struct obd_uuid *uuid);
int ptlrpc_connection_put(struct ptlrpc_connection *c);
struct ptlrpc_connection *ptlrpc_connection_addref(struct ptlrpc_connection *);
int ptlrpc_connection_init(void);
void ptlrpc_connection_fini(void);

/* ptlrpc/niobuf.c */
/**
 * Actual interfacing with LNet to put/get/register/unregister stuff
 * @{
 */

int ptlrpc_unregister_bulk(struct ptlrpc_request *req, int async);

static inline int ptlrpc_client_bulk_active(struct ptlrpc_request *req)
{
        struct ptlrpc_bulk_desc *desc;
        int                   rc;

        desc = req->rq_bulk;

        if (req->rq_bulk_deadline > ktime_get_real_seconds())
                return 1;

        if (!desc)
                return 0;

        spin_lock(&desc->bd_lock);
        rc = desc->bd_md_count;
        spin_unlock(&desc->bd_lock);
        return rc;
}

#define PTLRPC_REPLY_MAYBE_DIFFICULT 0x01
#define PTLRPC_REPLY_EARLY         0x02
int ptlrpc_send_reply(struct ptlrpc_request *req, int flags);
int ptlrpc_reply(struct ptlrpc_request *req);
int ptlrpc_send_error(struct ptlrpc_request *req, int difficult);
int ptlrpc_error(struct ptlrpc_request *req);
void ptlrpc_resend_req(struct ptlrpc_request *request);
int ptlrpc_at_get_net_latency(struct ptlrpc_request *req);
int ptl_send_rpc(struct ptlrpc_request *request, int noreply);
int ptlrpc_register_rqbd(struct ptlrpc_request_buffer_desc *rqbd);
/** @} */

/* ptlrpc/client.c */
/**
 * Client-side portals API. Everything to send requests, receive replies,
 * request queues, request management, etc.
 * @{
 */
void ptlrpc_request_committed(struct ptlrpc_request *req, int force);

void ptlrpc_init_client(int req_portal, int rep_portal, char *name,
                        struct ptlrpc_client *);
struct ptlrpc_connection *ptlrpc_uuid_to_connection(struct obd_uuid *uuid);

int ptlrpc_queue_wait(struct ptlrpc_request *req);
int ptlrpc_replay_req(struct ptlrpc_request *req);
int ptlrpc_unregister_reply(struct ptlrpc_request *req, int async);
void ptlrpc_abort_inflight(struct obd_import *imp);
void ptlrpc_abort_set(struct ptlrpc_request_set *set);

struct ptlrpc_request_set *ptlrpc_prep_set(void);
struct ptlrpc_request_set *ptlrpc_prep_fcset(int max, set_producer_func func,
                                             void *arg);
int ptlrpc_set_next_timeout(struct ptlrpc_request_set *);
int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set);
int ptlrpc_set_wait(struct ptlrpc_request_set *);
int ptlrpc_expired_set(void *data);
void ptlrpc_interrupted_set(void *data);
void ptlrpc_mark_interrupted(struct ptlrpc_request *req);
void ptlrpc_set_destroy(struct ptlrpc_request_set *);
void ptlrpc_set_add_req(struct ptlrpc_request_set *, struct ptlrpc_request *);
void ptlrpc_set_add_new_req(struct ptlrpcd_ctl *pc,
                            struct ptlrpc_request *req);

void ptlrpc_free_rq_pool(struct ptlrpc_request_pool *pool);
int ptlrpc_add_rqs_to_pool(struct ptlrpc_request_pool *pool, int num_rq);

struct ptlrpc_request_pool *
ptlrpc_init_rq_pool(int, int,
                    int (*populate_pool)(struct ptlrpc_request_pool *, int));

void ptlrpc_at_set_req_timeout(struct ptlrpc_request *req);
struct ptlrpc_request *ptlrpc_request_alloc(struct obd_import *imp,
                                            const struct req_format *format);
struct ptlrpc_request *ptlrpc_request_alloc_pool(struct obd_import *imp,
                                                 struct ptlrpc_request_pool *,
                                                 const struct req_format *);
void ptlrpc_request_free(struct ptlrpc_request *request);
int ptlrpc_request_pack(struct ptlrpc_request *request,
                        __u32 version, int opcode);
struct ptlrpc_request *ptlrpc_request_alloc_pack(struct obd_import *,
                                                 const struct req_format *,
                                                 __u32, int);
int ptlrpc_request_bufs_pack(struct ptlrpc_request *request,
                             __u32 version, int opcode, char **bufs,
                             struct ptlrpc_cli_ctx *ctx);
void ptlrpc_req_finished(struct ptlrpc_request *request);
struct ptlrpc_request *ptlrpc_request_addref(struct ptlrpc_request *req);
struct ptlrpc_bulk_desc *ptlrpc_prep_bulk_imp(struct ptlrpc_request *req,
                                              unsigned npages, unsigned max_brw,
                                              unsigned type, unsigned portal);
void __ptlrpc_free_bulk(struct ptlrpc_bulk_desc *bulk, int pin);
static inline void ptlrpc_free_bulk_pin(struct ptlrpc_bulk_desc *bulk)
{
        __ptlrpc_free_bulk(bulk, 1);
}

static inline void ptlrpc_free_bulk_nopin(struct ptlrpc_bulk_desc *bulk)
{
        __ptlrpc_free_bulk(bulk, 0);
}

void __ptlrpc_prep_bulk_page(struct ptlrpc_bulk_desc *desc,
                             struct page *page, int pageoffset, int len, int);
static inline void ptlrpc_prep_bulk_page_pin(struct ptlrpc_bulk_desc *desc,
                                             struct page *page, int pageoffset,
                                             int len)
{
        __ptlrpc_prep_bulk_page(desc, page, pageoffset, len, 1);
}

static inline void ptlrpc_prep_bulk_page_nopin(struct ptlrpc_bulk_desc *desc,
                                               struct page *page, int pageoffset,
                                               int len)
{
        __ptlrpc_prep_bulk_page(desc, page, pageoffset, len, 0);
}

void ptlrpc_retain_replayable_request(struct ptlrpc_request *req,
                                      struct obd_import *imp);
__u64 ptlrpc_next_xid(void);
__u64 ptlrpc_sample_next_xid(void);
__u64 ptlrpc_req_xid(struct ptlrpc_request *request);

/* Set of routines to run a function in ptlrpcd context */
void *ptlrpcd_alloc_work(struct obd_import *imp,
                         int (*cb)(const struct lu_env *, void *), void *data);
void ptlrpcd_destroy_work(void *handler);
int ptlrpcd_queue_work(void *handler);

/** @} */
struct ptlrpc_service_buf_conf {
        /* nbufs is buffers # to allocate when growing the pool */
        unsigned int                    bc_nbufs;
        /* buffer size to post */
        unsigned int                    bc_buf_size;
        /* portal to listed for requests on */
        unsigned int                    bc_req_portal;
        /* portal of where to send replies to */
        unsigned int                    bc_rep_portal;
        /* maximum request size to be accepted for this service */
        unsigned int                    bc_req_max_size;
        /* maximum reply size this service can ever send */
        unsigned int                    bc_rep_max_size;
};

struct ptlrpc_service_thr_conf {
        /* threadname should be 8 characters or less - 6 will be added on */
        char                            *tc_thr_name;
        /* threads increasing factor for each CPU */
        unsigned int                    tc_thr_factor;
        /* service threads # to start on each partition while initializing */
        unsigned int                    tc_nthrs_init;
        /*
         * low water of threads # upper-limit on each partition while running,
         * service availability may be impacted if threads number is lower
         * than this value. It can be ZERO if the service doesn't require
         * CPU affinity or there is only one partition.
         */
        unsigned int                    tc_nthrs_base;
        /* "soft" limit for total threads number */
        unsigned int                    tc_nthrs_max;
        /* user specified threads number, it will be validated due to
         * other members of this structure.
         */
        unsigned int                    tc_nthrs_user;
        /* set NUMA node affinity for service threads */
        unsigned int                    tc_cpu_affinity;
        /* Tags for lu_context associated with service thread */
        __u32                           tc_ctx_tags;
};

struct ptlrpc_service_cpt_conf {
        struct cfs_cpt_table            *cc_cptable;
        /* string pattern to describe CPTs for a service */
        char                            *cc_pattern;
};

struct ptlrpc_service_conf {
        /* service name */
        char                            *psc_name;
        /* soft watchdog timeout multiplifier to print stuck service traces */
        unsigned int                    psc_watchdog_factor;
        /* buffer information */
        struct ptlrpc_service_buf_conf  psc_buf;
        /* thread information */
        struct ptlrpc_service_thr_conf  psc_thr;
        /* CPU partition information */
        struct ptlrpc_service_cpt_conf  psc_cpt;
        /* function table */
        struct ptlrpc_service_ops       psc_ops;
};

/* ptlrpc/service.c */
/**
 * Server-side services API. Register/unregister service, request state
 * management, service thread management
 *
 * @{
 */
void ptlrpc_dispatch_difficult_reply(struct ptlrpc_reply_state *rs);
void ptlrpc_schedule_difficult_reply(struct ptlrpc_reply_state *rs);
struct ptlrpc_service *ptlrpc_register_service(struct ptlrpc_service_conf *conf,
                                               struct kset *parent,
                                               struct dentry *debugfs_entry);

int ptlrpc_start_threads(struct ptlrpc_service *svc);
int ptlrpc_unregister_service(struct ptlrpc_service *service);

int ptlrpc_hr_init(void);
void ptlrpc_hr_fini(void);

/** @} */

/* ptlrpc/import.c */
/**
 * Import API
 * @{
 */
int ptlrpc_connect_import(struct obd_import *imp);
int ptlrpc_init_import(struct obd_import *imp);
int ptlrpc_disconnect_import(struct obd_import *imp, int noclose);
int ptlrpc_import_recovery_state_machine(struct obd_import *imp);

/* ptlrpc/pack_generic.c */
int ptlrpc_reconnect_import(struct obd_import *imp);
/** @} */

/**
 * ptlrpc msg buffer and swab interface
 *
 * @{
 */
int ptlrpc_buf_need_swab(struct ptlrpc_request *req, const int inout,
                         int index);
void ptlrpc_buf_set_swabbed(struct ptlrpc_request *req, const int inout,
                            int index);
int ptlrpc_unpack_rep_msg(struct ptlrpc_request *req, int len);
int ptlrpc_unpack_req_msg(struct ptlrpc_request *req, int len);

void lustre_init_msg_v2(struct lustre_msg_v2 *msg, int count, __u32 *lens,
                        char **bufs);
int lustre_pack_request(struct ptlrpc_request *, __u32 magic, int count,
                        __u32 *lens, char **bufs);
int lustre_pack_reply(struct ptlrpc_request *, int count, __u32 *lens,
                      char **bufs);
int lustre_pack_reply_v2(struct ptlrpc_request *req, int count,
                         __u32 *lens, char **bufs, int flags);
#define LPRFL_EARLY_REPLY 1
int lustre_pack_reply_flags(struct ptlrpc_request *, int count, __u32 *lens,
                            char **bufs, int flags);
int lustre_shrink_msg(struct lustre_msg *msg, int segment,
                      unsigned int newlen, int move_data);
void lustre_free_reply_state(struct ptlrpc_reply_state *rs);
int __lustre_unpack_msg(struct lustre_msg *m, int len);
int lustre_msg_hdr_size(__u32 magic, int count);
int lustre_msg_size(__u32 magic, int count, __u32 *lengths);
int lustre_msg_size_v2(int count, __u32 *lengths);
int lustre_packed_msg_size(struct lustre_msg *msg);
int lustre_msg_early_size(void);
void *lustre_msg_buf_v2(struct lustre_msg_v2 *m, int n, int min_size);
void *lustre_msg_buf(struct lustre_msg *m, int n, int minlen);
int lustre_msg_buflen(struct lustre_msg *m, int n);
int lustre_msg_bufcount(struct lustre_msg *m);
char *lustre_msg_string(struct lustre_msg *m, int n, int max_len);
__u32 lustre_msghdr_get_flags(struct lustre_msg *msg);
void lustre_msghdr_set_flags(struct lustre_msg *msg, __u32 flags);
__u32 lustre_msg_get_flags(struct lustre_msg *msg);
void lustre_msg_add_flags(struct lustre_msg *msg, int flags);
void lustre_msg_set_flags(struct lustre_msg *msg, int flags);
void lustre_msg_clear_flags(struct lustre_msg *msg, int flags);
__u32 lustre_msg_get_op_flags(struct lustre_msg *msg);
void lustre_msg_add_op_flags(struct lustre_msg *msg, int flags);
struct lustre_handle *lustre_msg_get_handle(struct lustre_msg *msg);
__u32 lustre_msg_get_type(struct lustre_msg *msg);
void lustre_msg_add_version(struct lustre_msg *msg, int version);
__u32 lustre_msg_get_opc(struct lustre_msg *msg);
__u64 lustre_msg_get_last_committed(struct lustre_msg *msg);
__u64 *lustre_msg_get_versions(struct lustre_msg *msg);
__u64 lustre_msg_get_transno(struct lustre_msg *msg);
__u64 lustre_msg_get_slv(struct lustre_msg *msg);
__u32 lustre_msg_get_limit(struct lustre_msg *msg);
void lustre_msg_set_slv(struct lustre_msg *msg, __u64 slv);
void lustre_msg_set_limit(struct lustre_msg *msg, __u64 limit);
int lustre_msg_get_status(struct lustre_msg *msg);
__u32 lustre_msg_get_conn_cnt(struct lustre_msg *msg);
__u32 lustre_msg_get_magic(struct lustre_msg *msg);
__u32 lustre_msg_get_timeout(struct lustre_msg *msg);
__u32 lustre_msg_get_service_time(struct lustre_msg *msg);
__u32 lustre_msg_get_cksum(struct lustre_msg *msg);
__u32 lustre_msg_calc_cksum(struct lustre_msg *msg);
void lustre_msg_set_handle(struct lustre_msg *msg,
                           struct lustre_handle *handle);
void lustre_msg_set_type(struct lustre_msg *msg, __u32 type);
void lustre_msg_set_opc(struct lustre_msg *msg, __u32 opc);
void lustre_msg_set_versions(struct lustre_msg *msg, __u64 *versions);
void lustre_msg_set_transno(struct lustre_msg *msg, __u64 transno);
void lustre_msg_set_status(struct lustre_msg *msg, __u32 status);
void lustre_msg_set_conn_cnt(struct lustre_msg *msg, __u32 conn_cnt);
void ptlrpc_request_set_replen(struct ptlrpc_request *req);
void lustre_msg_set_timeout(struct lustre_msg *msg, __u32 timeout);
void lustre_msg_set_service_time(struct lustre_msg *msg, __u32 service_time);
void lustre_msg_set_jobid(struct lustre_msg *msg, char *jobid);
void lustre_msg_set_cksum(struct lustre_msg *msg, __u32 cksum);

static inline void
lustre_shrink_reply(struct ptlrpc_request *req, int segment,
                    unsigned int newlen, int move_data)
{
        LASSERT(req->rq_reply_state);
        LASSERT(req->rq_repmsg);
        req->rq_replen = lustre_shrink_msg(req->rq_repmsg, segment,
                                           newlen, move_data);
}

#ifdef CONFIG_LUSTRE_TRANSLATE_ERRNOS

static inline int ptlrpc_status_hton(int h)
{
        /*
         * Positive errnos must be network errnos, such as LUSTRE_EDEADLK,
         * ELDLM_LOCK_ABORTED, etc.
         */
        if (h < 0)
                return -lustre_errno_hton(-h);
        else
                return h;
}

static inline int ptlrpc_status_ntoh(int n)
{
        /*
         * See the comment in ptlrpc_status_hton().
         */
        if (n < 0)
                return -lustre_errno_ntoh(-n);
        else
                return n;
}

#else

#define ptlrpc_status_hton(h) (h)
#define ptlrpc_status_ntoh(n) (n)

#endif
/** @} */

/** Change request phase of \a req to \a new_phase */
static inline void
ptlrpc_rqphase_move(struct ptlrpc_request *req, enum rq_phase new_phase)
{
        if (req->rq_phase == new_phase)
                return;

        if (new_phase == RQ_PHASE_UNREG_RPC ||
            new_phase == RQ_PHASE_UNREG_BULK) {
                /* No embedded unregistering phases */
                if (req->rq_phase == RQ_PHASE_UNREG_RPC ||
                    req->rq_phase == RQ_PHASE_UNREG_BULK)
                        return;

                req->rq_next_phase = req->rq_phase;
                if (req->rq_import)
                        atomic_inc(&req->rq_import->imp_unregistering);
        }

        if (req->rq_phase == RQ_PHASE_UNREG_RPC ||
            req->rq_phase == RQ_PHASE_UNREG_BULK) {
                if (req->rq_import)
                        atomic_dec(&req->rq_import->imp_unregistering);
        }

        DEBUG_REQ(D_INFO, req, "move req \"%s\" -> \"%s\"",
                  ptlrpc_rqphase2str(req), ptlrpc_phase2str(new_phase));

        req->rq_phase = new_phase;
}

/**
 * Returns true if request \a req got early reply and hard deadline is not met
 */
static inline int
ptlrpc_client_early(struct ptlrpc_request *req)
{
        return req->rq_early;
}

/**
 * Returns true if we got real reply from server for this request
 */
static inline int
ptlrpc_client_replied(struct ptlrpc_request *req)
{
        if (req->rq_reply_deadline > ktime_get_real_seconds())
                return 0;
        return req->rq_replied;
}

/** Returns true if request \a req is in process of receiving server reply */
static inline int
ptlrpc_client_recv(struct ptlrpc_request *req)
{
        if (req->rq_reply_deadline > ktime_get_real_seconds())
                return 1;
        return req->rq_receiving_reply;
}

static inline int
ptlrpc_client_recv_or_unlink(struct ptlrpc_request *req)
{
        int rc;

        spin_lock(&req->rq_lock);
        if (req->rq_reply_deadline > ktime_get_real_seconds()) {
                spin_unlock(&req->rq_lock);
                return 1;
        }
        if (req->rq_req_deadline > ktime_get_real_seconds()) {
                spin_unlock(&req->rq_lock);
                return 1;
        }
        rc = !req->rq_req_unlinked || !req->rq_reply_unlinked ||
             req->rq_receiving_reply;
        spin_unlock(&req->rq_lock);
        return rc;
}

static inline void
ptlrpc_client_wake_req(struct ptlrpc_request *req)
{
        if (!req->rq_set)
                wake_up(&req->rq_reply_waitq);
        else
                wake_up(&req->rq_set->set_waitq);
}

static inline void
ptlrpc_rs_addref(struct ptlrpc_reply_state *rs)
{
        LASSERT(atomic_read(&rs->rs_refcount) > 0);
        atomic_inc(&rs->rs_refcount);
}

static inline void
ptlrpc_rs_decref(struct ptlrpc_reply_state *rs)
{
        LASSERT(atomic_read(&rs->rs_refcount) > 0);
        if (atomic_dec_and_test(&rs->rs_refcount))
                lustre_free_reply_state(rs);
}

/* Should only be called once per req */
static inline void ptlrpc_req_drop_rs(struct ptlrpc_request *req)
{
        if (!req->rq_reply_state)
                return; /* shouldn't occur */
        ptlrpc_rs_decref(req->rq_reply_state);
        req->rq_reply_state = NULL;
        req->rq_repmsg = NULL;
}

static inline __u32 lustre_request_magic(struct ptlrpc_request *req)
{
        return lustre_msg_get_magic(req->rq_reqmsg);
}

static inline int ptlrpc_req_get_repsize(struct ptlrpc_request *req)
{
        switch (req->rq_reqmsg->lm_magic) {
        case LUSTRE_MSG_MAGIC_V2:
                return req->rq_reqmsg->lm_repsize;
        default:
                LASSERTF(0, "incorrect message magic: %08x\n",
                         req->rq_reqmsg->lm_magic);
                return -EFAULT;
        }
}

static inline int ptlrpc_send_limit_expired(struct ptlrpc_request *req)
{
        if (req->rq_delay_limit != 0 &&
            time_before(cfs_time_add(req->rq_queued_time,
                                     cfs_time_seconds(req->rq_delay_limit)),
                        cfs_time_current())) {
                return 1;
        }
        return 0;
}

static inline int ptlrpc_no_resend(struct ptlrpc_request *req)
{
        if (!req->rq_no_resend && ptlrpc_send_limit_expired(req)) {
                spin_lock(&req->rq_lock);
                req->rq_no_resend = 1;
                spin_unlock(&req->rq_lock);
        }
        return req->rq_no_resend;
}

static inline int
ptlrpc_server_get_timeout(struct ptlrpc_service_part *svcpt)
{
        int at = AT_OFF ? 0 : at_get(&svcpt->scp_at_estimate);

        return svcpt->scp_service->srv_watchdog_factor *
               max_t(int, at, obd_timeout);
}

static inline struct ptlrpc_service *
ptlrpc_req2svc(struct ptlrpc_request *req)
{
        return req->rq_rqbd->rqbd_svcpt->scp_service;
}

/* ldlm/ldlm_lib.c */
/**
 * Target client logic
 * @{
 */
int client_obd_setup(struct obd_device *obddev, struct lustre_cfg *lcfg);
int client_obd_cleanup(struct obd_device *obddev);
int client_connect_import(const struct lu_env *env,
                          struct obd_export **exp, struct obd_device *obd,
                          struct obd_uuid *cluuid, struct obd_connect_data *,
                          void *localdata);
int client_disconnect_export(struct obd_export *exp);
int client_import_add_conn(struct obd_import *imp, struct obd_uuid *uuid,
                           int priority);
int client_import_del_conn(struct obd_import *imp, struct obd_uuid *uuid);
int client_import_find_conn(struct obd_import *imp, lnet_nid_t peer,
                            struct obd_uuid *uuid);
int import_set_conn_priority(struct obd_import *imp, struct obd_uuid *uuid);
void client_destroy_import(struct obd_import *imp);
/** @} */

/* ptlrpc/pinger.c */
/**
 * Pinger API (client side only)
 * @{
 */
enum timeout_event {
        TIMEOUT_GRANT = 1
};

struct timeout_item;
typedef int (*timeout_cb_t)(struct timeout_item *, void *);
int ptlrpc_pinger_add_import(struct obd_import *imp);
int ptlrpc_pinger_del_import(struct obd_import *imp);
int ptlrpc_add_timeout_client(int time, enum timeout_event event,
                              timeout_cb_t cb, void *data,
                              struct list_head *obd_list);
int ptlrpc_del_timeout_client(struct list_head *obd_list,
                              enum timeout_event event);
struct ptlrpc_request *ptlrpc_prep_ping(struct obd_import *imp);
int ptlrpc_obd_ping(struct obd_device *obd);
void ptlrpc_pinger_ir_up(void);
void ptlrpc_pinger_ir_down(void);
/** @} */
int ptlrpc_pinger_suppress_pings(void);

/* ptlrpc/ptlrpcd.c */
void ptlrpcd_stop(struct ptlrpcd_ctl *pc, int force);
void ptlrpcd_free(struct ptlrpcd_ctl *pc);
void ptlrpcd_wake(struct ptlrpc_request *req);
void ptlrpcd_add_req(struct ptlrpc_request *req);
int ptlrpcd_addref(void);
void ptlrpcd_decref(void);

/* ptlrpc/lproc_ptlrpc.c */
/**
 * procfs output related functions
 * @{
 */
const char *ll_opcode2str(__u32 opcode);
void ptlrpc_lprocfs_register_obd(struct obd_device *obd);
void ptlrpc_lprocfs_unregister_obd(struct obd_device *obd);
void ptlrpc_lprocfs_brw(struct ptlrpc_request *req, int bytes);
/** @} */

/* ptlrpc/llog_client.c */
extern struct llog_operations llog_client_ops;
/** @} net */

#endif
/** @} PtlRPC */