/*
 *  Copyright (c) 2001 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Kendrick Smith <kmsmith@umich.edu>
 *  Andy Adamson <andros@umich.edu>
 *  
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef _NFSD4_STATE_H
#define _NFSD4_STATE_H

#include <crypto/md5.h>
#include <linux/idr.h>
#include <linux/refcount.h>
#include <linux/sunrpc/svc_xprt.h>
#include "nfsfh.h"
#include "nfsd.h"

typedef struct {
        u32             cl_boot;
        u32             cl_id;
} clientid_t;

typedef struct {
        clientid_t      so_clid;
        u32             so_id;
} stateid_opaque_t;

typedef struct {
        u32                     si_generation;
        stateid_opaque_t        si_opaque;
} stateid_t;

typedef struct {
        stateid_t               cs_stid;
#define NFS4_COPY_STID 1
#define NFS4_COPYNOTIFY_STID 2
        unsigned char           cs_type;
        refcount_t              cs_count;
} copy_stateid_t;

struct nfsd4_referring_call {
        struct list_head        __list;

        u32                     rc_sequenceid;
        u32                     rc_slotid;
};

struct nfsd4_referring_call_list {
        struct list_head        __list;

        struct nfs4_sessionid   rcl_sessionid;
        int                     __nr_referring_calls;
        struct list_head        rcl_referring_calls;
};

struct nfsd4_callback {
        struct nfs4_client *cb_clp;
        struct rpc_message cb_msg;
#define NFSD4_CALLBACK_RUNNING          (0)
#define NFSD4_CALLBACK_WAKE             (1)
#define NFSD4_CALLBACK_REQUEUE          (2)
        unsigned long cb_flags;
        const struct nfsd4_callback_ops *cb_ops;
        struct work_struct cb_work;
        int cb_seq_status;
        int cb_status;
        int cb_held_slot;

        int cb_nr_referring_call_list;
        struct list_head cb_referring_call_list;
};

struct nfsd4_callback_ops {
        void (*prepare)(struct nfsd4_callback *);
        int (*done)(struct nfsd4_callback *, struct rpc_task *);
        void (*release)(struct nfsd4_callback *);
        uint32_t opcode;
};

/*
 * A core object that represents a "common" stateid. These are generally
 * embedded within the different (more specific) stateid objects and contain
 * fields that are of general use to any stateid.
 */
struct nfs4_stid {
        refcount_t              sc_count;

        /* A new stateid is added to the cl_stateids idr early before it
         * is fully initialised.  Its sc_type is then zero.  After
         * initialisation the sc_type it set under cl_lock, and then
         * never changes.
         */
#define SC_TYPE_OPEN            BIT(0)
#define SC_TYPE_LOCK            BIT(1)
#define SC_TYPE_DELEG           BIT(2)
#define SC_TYPE_LAYOUT          BIT(3)
        unsigned short          sc_type;

/* state_lock protects sc_status for delegation stateids.
 * ->cl_lock protects sc_status for open and lock stateids.
 * ->st_mutex also protect sc_status for open stateids.
 * ->ls_lock protects sc_status for layout stateids.
 */
/*
 * For an open stateid kept around *only* to process close replays.
 * For deleg stateid, kept in idr until last reference is dropped.
 */
#define SC_STATUS_CLOSED        BIT(0)
/* For a deleg stateid kept around only to process free_stateid's: */
#define SC_STATUS_REVOKED       BIT(1)
#define SC_STATUS_ADMIN_REVOKED BIT(2)
#define SC_STATUS_FREEABLE      BIT(3)
#define SC_STATUS_FREED         BIT(4)
        unsigned short          sc_status;

        struct list_head        sc_cp_list;
        stateid_t               sc_stateid;
        spinlock_t              sc_lock;
        struct nfs4_client      *sc_client;
        struct nfs4_file        *sc_file;
        void                    (*sc_free)(struct nfs4_stid *);
};

/* Keep a list of stateids issued by the COPY_NOTIFY, associate it with the
 * parent OPEN/LOCK/DELEG stateid.
 */
struct nfs4_cpntf_state {
        copy_stateid_t          cp_stateid;
        struct list_head        cp_list;        /* per parent nfs4_stid */
        stateid_t               cp_p_stateid;   /* copy of parent's stateid */
        clientid_t              cp_p_clid;      /* copy of parent's clid */
        time64_t                cpntf_time;     /* last time stateid used */
};

/*
 * RFC 7862 Section 4.8 states:
 *
 * | A copy offload stateid will be valid until either (A) the client
 * | or server restarts or (B) the client returns the resource by
 * | issuing an OFFLOAD_CANCEL operation or the client replies to a
 * | CB_OFFLOAD operation.
 *
 * Because a client might not reply to a CB_OFFLOAD, or a reply
 * might get lost due to connection loss, NFSD purges async copy
 * state after a short period to prevent it from accumulating
 * over time.
 */
#define NFSD_COPY_INITIAL_TTL 10

struct nfs4_cb_fattr {
        struct nfsd4_callback ncf_getattr;
        u32 ncf_cb_status;

        /* from CB_GETATTR reply */
        u64 ncf_cb_change;
        u64 ncf_cb_fsize;
        struct timespec64 ncf_cb_mtime;
        struct timespec64 ncf_cb_atime;

        bool ncf_file_modified;
        u64 ncf_initial_cinfo;
        u64 ncf_cur_fsize;
};

/*
 * Represents a delegation stateid. The nfs4_client holds references to these
 * and they are put when it is being destroyed or when the delegation is
 * returned by the client:
 *
 * o 1 reference as long as a delegation is still in force (taken when it's
 *   alloc'd, put when it's returned or revoked)
 *
 * o 1 reference as long as a recall rpc is in progress (taken when the lease
 *   is broken, put when the rpc exits)
 *
 * o 1 more ephemeral reference for each nfsd thread currently doing something
 *   with that delegation without holding the cl_lock
 *
 * If the server attempts to recall a delegation and the client doesn't do so
 * before a timeout, the server may also revoke the delegation. In that case,
 * the object will either be destroyed (v4.0) or moved to a per-client list of
 * revoked delegations (v4.1+).
 *
 * This object is a superset of the nfs4_stid.
 */
struct nfs4_delegation {
        struct nfs4_stid        dl_stid; /* must be first field */
        struct list_head        dl_perfile;
        struct list_head        dl_perclnt;
        struct list_head        dl_recall_lru;  /* delegation recalled */
        struct nfs4_clnt_odstate *dl_clnt_odstate;
        time64_t                dl_time;
        u32                     dl_type;
        /* For recall: */
        int                     dl_retries;
        struct nfsd4_callback   dl_recall;
        bool                    dl_recalled;
        bool                    dl_written;
        bool                    dl_setattr;

        /* for CB_GETATTR */
        struct nfs4_cb_fattr    dl_cb_fattr;

        /* For delegated timestamps */
        struct timespec64       dl_atime;
        struct timespec64       dl_mtime;
        struct timespec64       dl_ctime;
};

static inline bool deleg_is_read(u32 dl_type)
{
        return (dl_type == OPEN_DELEGATE_READ || dl_type == OPEN_DELEGATE_READ_ATTRS_DELEG);
}

static inline bool deleg_is_write(u32 dl_type)
{
        return (dl_type == OPEN_DELEGATE_WRITE || dl_type == OPEN_DELEGATE_WRITE_ATTRS_DELEG);
}

static inline bool deleg_attrs_deleg(u32 dl_type)
{
        return dl_type == OPEN_DELEGATE_READ_ATTRS_DELEG ||
               dl_type == OPEN_DELEGATE_WRITE_ATTRS_DELEG;
}

bool nfsd4_vet_deleg_time(struct timespec64 *cb, const struct timespec64 *orig,
                          const struct timespec64 *now);

#define cb_to_delegation(cb) \
        container_of(cb, struct nfs4_delegation, dl_recall)

/* client delegation callback info */
struct nfs4_cb_conn {
        /* SETCLIENTID info */
        struct sockaddr_storage cb_addr;
        struct sockaddr_storage cb_saddr;
        size_t                  cb_addrlen;
        u32                     cb_prog; /* used only in 4.0 case;
                                            per-session otherwise */
        u32                     cb_ident;       /* minorversion 0 only */
        struct svc_xprt         *cb_xprt;       /* minorversion 1 only */
};

static inline struct nfs4_delegation *delegstateid(struct nfs4_stid *s)
{
        return container_of(s, struct nfs4_delegation, dl_stid);
}

/* Maximum number of slots per session.  This is for sanity-check only.
 * It could be increased if we had a mechanism to shutdown misbehaving clients.
 * A large number can be needed to get good throughput on high-latency servers.
 */
#define NFSD_MAX_SLOTS_PER_SESSION      2048
/* Maximum  session per slot cache size */
#define NFSD_SLOT_CACHE_SIZE            2048
/* Maximum number of NFSD_SLOT_CACHE_SIZE slots per session */
#define NFSD_CACHE_SIZE_SLOTS_PER_SESSION       32
#define NFSD_MAX_MEM_PER_SESSION  \
                (NFSD_CACHE_SIZE_SLOTS_PER_SESSION * NFSD_SLOT_CACHE_SIZE)

struct nfsd4_slot {
        u32     sl_seqid;
        __be32  sl_status;
        struct svc_cred sl_cred;
        u32     sl_index;
        u32     sl_datalen;
        u16     sl_opcnt;
        u16     sl_generation;
#define NFSD4_SLOT_INUSE        (1 << 0)
#define NFSD4_SLOT_CACHETHIS    (1 << 1)
#define NFSD4_SLOT_INITIALIZED  (1 << 2)
#define NFSD4_SLOT_CACHED       (1 << 3)
#define NFSD4_SLOT_REUSED       (1 << 4)
        u8      sl_flags;
        char    sl_data[];
};

struct nfsd4_channel_attrs {
        u32             headerpadsz;
        u32             maxreq_sz;
        u32             maxresp_sz;
        u32             maxresp_cached;
        u32             maxops;
        u32             maxreqs;
        u32             nr_rdma_attrs;
        u32             rdma_attrs;
};

struct nfsd4_cb_sec {
        u32     flavor; /* (u32)(-1) used to mean "no valid flavor" */
        kuid_t  uid;
        kgid_t  gid;
};

struct nfsd4_create_session {
        clientid_t                      clientid;
        struct nfs4_sessionid           sessionid;
        u32                             seqid;
        u32                             flags;
        struct nfsd4_channel_attrs      fore_channel;
        struct nfsd4_channel_attrs      back_channel;
        u32                             callback_prog;
        struct nfsd4_cb_sec             cb_sec;
};

struct nfsd4_backchannel_ctl {
        u32     bc_cb_program;
        struct nfsd4_cb_sec             bc_cb_sec;
};

struct nfsd4_bind_conn_to_session {
        struct nfs4_sessionid           sessionid;
        u32                             dir;
};

/* The single slot clientid cache structure */
struct nfsd4_clid_slot {
        u32                             sl_seqid;
        __be32                          sl_status;
        struct nfsd4_create_session     sl_cr_ses;
};

struct nfsd4_conn {
        struct list_head cn_persession;
        struct svc_xprt *cn_xprt;
        struct svc_xpt_user cn_xpt_user;
        struct nfsd4_session *cn_session;
/* CDFC4_FORE, CDFC4_BACK: */
        unsigned char cn_flags;
};

/* Maximum number of slots that nfsd will use in the backchannel */
#define NFSD_BC_SLOT_TABLE_SIZE         (sizeof(u32) * 8)

/*
 * Representation of a v4.1+ session. These are refcounted in a similar fashion
 * to the nfs4_client. References are only taken when the server is actively
 * working on the object (primarily during the processing of compounds).
 */
struct nfsd4_session {
        atomic_t                se_ref;
        spinlock_t              se_lock;
        u32                     se_cb_slot_avail; /* bitmap of available slots */
        u32                     se_cb_highest_slot;     /* highest slot client wants */
        u32                     se_cb_prog;
        struct list_head        se_hash;        /* hash by sessionid */
        struct list_head        se_perclnt;
        struct list_head        se_all_sessions;/* global list of sessions */
        struct nfs4_client      *se_client;
        struct nfs4_sessionid   se_sessionid;
        struct nfsd4_channel_attrs se_fchannel;
        struct nfsd4_cb_sec     se_cb_sec;
        struct list_head        se_conns;
        u32                     se_cb_seq_nr[NFSD_BC_SLOT_TABLE_SIZE];
        struct xarray           se_slots;       /* forward channel slots */
        u16                     se_slot_gen;
        bool                    se_dead;
        u32                     se_target_maxslots;
};

/* formatted contents of nfs4_sessionid */
struct nfsd4_sessionid {
        clientid_t      clientid;
        u32             sequence;
        u32             reserved;
};

/* Length of MD5 digest as hex, plus terminating '\0' */
#define HEXDIR_LEN      (2 * MD5_DIGEST_SIZE + 1)

/*
 *       State                Meaning                  Where set
 * --------------------------------------------------------------------------
 * | NFSD4_ACTIVE      | Confirmed, active    | Default                     |
 * |------------------- ----------------------------------------------------|
 * | NFSD4_COURTESY    | Courtesy state.      | nfs4_get_client_reaplist    |
 * |                   | Lease/lock/share     |                             |
 * |                   | reservation conflict |                             |
 * |                   | can cause Courtesy   |                             |
 * |                   | client to be expired |                             |
 * |------------------------------------------------------------------------|
 * | NFSD4_EXPIRABLE   | Courtesy client to be| nfs4_laundromat             |
 * |                   | expired by Laundromat| try_to_expire_client        |
 * |                   | due to conflict      |                             |
 * |------------------------------------------------------------------------|
 */
enum {
        NFSD4_ACTIVE = 0,
        NFSD4_COURTESY,
        NFSD4_EXPIRABLE,
};

/*
 * struct nfs4_client - one per client.  Clientids live here.
 *
 * The initial object created by an NFS client using SETCLIENTID (for NFSv4.0)
 * or EXCHANGE_ID (for NFSv4.1+). These objects are refcounted and timestamped.
 * Each nfsd_net_ns object contains a set of these and they are tracked via
 * short and long form clientid. They are hashed and searched for under the
 * per-nfsd_net client_lock spinlock.
 *
 * References to it are only held during the processing of compounds, and in
 * certain other operations. In their "resting state" they have a refcount of
 * 0. If they are not renewed within a lease period, they become eligible for
 * destruction by the laundromat.
 *
 * These objects can also be destroyed if the client sends certain forms of
 * SETCLIENTID or EXCHANGE_ID operations.
 *
 * Care is taken *not* to do this however when the objects have an elevated
 * refcount.
 *
 * o Each nfs4_client is hashed by clientid
 *
 * o Each nfs4_clients is also hashed by name (the opaque quantity initially
 *   sent by the client to identify itself).
 *
 * o cl_perclient list is used to ensure no dangling stateowner references
 *   when we expire the nfs4_client
 */
struct nfs4_client {
        struct list_head        cl_idhash;      /* hash by cl_clientid.id */
        struct rb_node          cl_namenode;    /* link into by-name trees */
        struct list_head        *cl_ownerstr_hashtbl;
        struct list_head        cl_openowners;
        struct idr              cl_stateids;    /* stateid lookup */
        struct list_head        cl_delegations;
        struct list_head        cl_revoked;     /* unacknowledged, revoked 4.1 state */
        struct list_head        cl_lru;         /* tail queue */
#ifdef CONFIG_NFSD_PNFS
        struct list_head        cl_lo_states;   /* outstanding layout states */
#endif
        struct xdr_netobj       cl_name;        /* id generated by client */
        nfs4_verifier           cl_verifier;    /* generated by client */
        time64_t                cl_time;        /* time of last lease renewal */
        struct sockaddr_storage cl_addr;        /* client ipaddress */
        bool                    cl_mach_cred;   /* SP4_MACH_CRED in force */
        struct svc_cred         cl_cred;        /* setclientid principal */
        clientid_t              cl_clientid;    /* generated by server */
        nfs4_verifier           cl_confirm;     /* generated by server */
        u32                     cl_minorversion;
        atomic_t                cl_admin_revoked; /* count of admin-revoked states */
        /* NFSv4.1 client implementation id: */
        struct xdr_netobj       cl_nii_domain;
        struct xdr_netobj       cl_nii_name;
        struct timespec64       cl_nii_time;

        /* for v4.0 and v4.1 callbacks: */
        struct nfs4_cb_conn     cl_cb_conn;
#define NFSD4_CLIENT_CB_UPDATE          (0)
#define NFSD4_CLIENT_CB_KILL            (1)
#define NFSD4_CLIENT_STABLE             (2)     /* client on stable storage */
#define NFSD4_CLIENT_RECLAIM_COMPLETE   (3)     /* reclaim_complete done */
#define NFSD4_CLIENT_CONFIRMED          (4)     /* client is confirmed */
#define NFSD4_CLIENT_UPCALL_LOCK        (5)     /* upcall serialization */
#define NFSD4_CLIENT_CB_FLAG_MASK       (1 << NFSD4_CLIENT_CB_UPDATE | \
                                         1 << NFSD4_CLIENT_CB_KILL)
        unsigned long           cl_flags;

        struct workqueue_struct *cl_callback_wq;
        const struct cred       *cl_cb_cred;
        struct rpc_clnt         *cl_cb_client;
        u32                     cl_cb_ident;
#define NFSD4_CB_UP             0
#define NFSD4_CB_UNKNOWN        1
#define NFSD4_CB_DOWN           2
#define NFSD4_CB_FAULT          3
        int                     cl_cb_state;
        struct nfsd4_callback   cl_cb_null;
        struct nfsd4_session    *cl_cb_session;

        /* for all client information that callback code might need: */
        spinlock_t              cl_lock;

        /* for nfs41 */
        struct list_head        cl_sessions;
        struct nfsd4_clid_slot  cl_cs_slot;     /* create_session slot */
        u32                     cl_exchange_flags;
        /* number of rpc's in progress over an associated session: */
        atomic_t                cl_rpc_users;
        struct nfsdfs_client    cl_nfsdfs;
        struct nfs4_op_map      cl_spo_must_allow;

        /* debugging info directory under nfsd/clients/ : */
        struct dentry           *cl_nfsd_dentry;
        /* 'info' file within that directory. Ref is not counted,
         * but will remain valid iff cl_nfsd_dentry != NULL
         */
        struct dentry           *cl_nfsd_info_dentry;

        struct rpc_wait_queue   cl_cb_waitq;    /* backchannel callers may */
                                                /* wait here for slots */
        struct net              *net;
        struct list_head        async_copies;   /* list of async copies */
        spinlock_t              async_lock;     /* lock for async copies */
        atomic_t                cl_cb_inflight; /* Outstanding callbacks */

        unsigned int            cl_state;
        atomic_t                cl_delegs_in_recall;

        struct nfsd4_cb_recall_any      *cl_ra;
        time64_t                cl_ra_time;
};

/* struct nfs4_client_reset
 * one per old client. Populates reset_str_hashtbl. Filled from conf_id_hashtbl
 * upon lease reset, or from upcall to state_daemon (to read in state
 * from non-volitile storage) upon reboot.
 */
struct nfs4_client_reclaim {
        struct list_head        cr_strhash;     /* hash by cr_name */
        struct nfs4_client      *cr_clp;        /* pointer to associated clp */
        struct xdr_netobj       cr_name;        /* recovery dir name */
        struct xdr_netobj       cr_princhash;
};

/*
 * REPLAY_ISIZE is sized for an OPEN response with delegation:
 *   4(status) + 8(stateid) + 20(changeinfo) + 4(rflags) +
 *   8(verifier) + 4(deleg. type) + 8(deleg. stateid) +
 *   4(deleg. recall flag) + 20(deleg. space limit) +
 *   ~32(deleg. ace) = 112 bytes
 *
 * Some responses can exceed this. A LOCK denial includes the conflicting
 * lock owner, which can be up to 1024 bytes (NFS4_OPAQUE_LIMIT). Responses
 * larger than REPLAY_ISIZE are not cached in rp_ibuf; only rp_status is
 * saved. Enlarging this constant increases the size of every
 * nfs4_stateowner.
 */

#define NFSD4_REPLAY_ISIZE       112 

/*
 * Replay buffer, where the result of the last seqid-mutating operation 
 * is cached. 
 */
struct nfs4_replay {
        __be32                  rp_status;
        unsigned int            rp_buflen;
        char                    *rp_buf;
        struct knfsd_fh         rp_openfh;
        int                     rp_locked;
        char                    rp_ibuf[NFSD4_REPLAY_ISIZE];
};

struct nfs4_stateowner;

struct nfs4_stateowner_operations {
        void (*so_unhash)(struct nfs4_stateowner *);
        void (*so_free)(struct nfs4_stateowner *);
};

/*
 * A core object that represents either an open or lock owner. The object and
 * lock owner objects have one of these embedded within them. Refcounts and
 * other fields common to both owner types are contained within these
 * structures.
 */
struct nfs4_stateowner {
        struct list_head                        so_strhash;
        struct list_head                        so_stateids;
        struct nfs4_client                      *so_client;
        const struct nfs4_stateowner_operations *so_ops;
        /* after increment in nfsd4_bump_seqid, represents the next
         * sequence id expected from the client: */
        atomic_t                                so_count;
        u32                                     so_seqid;
        struct xdr_netobj                       so_owner; /* open owner name */
        struct nfs4_replay                      so_replay;
        bool                                    so_is_open_owner;
};

/*
 * When a file is opened, the client provides an open state owner opaque string
 * that indicates the "owner" of that open. These objects are refcounted.
 * References to it are held by each open state associated with it. This object
 * is a superset of the nfs4_stateowner struct.
 */
struct nfs4_openowner {
        struct nfs4_stateowner  oo_owner; /* must be first field */
        struct list_head        oo_perclient;
        /*
         * We keep around openowners a little while after last close,
         * which saves clients from having to confirm, and allows us to
         * handle close replays if they come soon enough.  The close_lru
         * is a list of such openowners, to be reaped by the laundromat
         * thread eventually if they remain unused:
         */
        struct list_head        oo_close_lru;
        struct nfs4_ol_stateid *oo_last_closed_stid;
        time64_t                oo_time; /* time of placement on so_close_lru */
#define NFS4_OO_CONFIRMED   1
        unsigned char           oo_flags;
};

/*
 * Represents a generic "lockowner". Similar to an openowner. References to it
 * are held by the lock stateids that are created on its behalf. This object is
 * a superset of the nfs4_stateowner struct.
 */
struct nfs4_lockowner {
        struct nfs4_stateowner  lo_owner;       /* must be first element */
        struct list_head        lo_blocked;     /* blocked file_locks */
};

static inline struct nfs4_openowner * openowner(struct nfs4_stateowner *so)
{
        return container_of(so, struct nfs4_openowner, oo_owner);
}

static inline struct nfs4_lockowner * lockowner(struct nfs4_stateowner *so)
{
        return container_of(so, struct nfs4_lockowner, lo_owner);
}

/*
 * Per-client state indicating no. of opens and outstanding delegations
 * on a file from a particular client.'od' stands for 'open & delegation'
 */
struct nfs4_clnt_odstate {
        struct nfs4_client      *co_client;
        struct nfs4_file        *co_file;
        struct list_head        co_perfile;
        refcount_t              co_odcount;
};

/*
 * nfs4_file: a file opened by some number of (open) nfs4_stateowners.
 *
 * These objects are global. nfsd keeps one instance of a nfs4_file per
 * filehandle (though it may keep multiple file descriptors for each). Each
 * inode can have multiple filehandles associated with it, so there is
 * (potentially) a many to one relationship between this struct and struct
 * inode.
 */
struct nfs4_file {
        refcount_t              fi_ref;
        struct inode *          fi_inode;
        bool                    fi_aliased;
        spinlock_t              fi_lock;
        struct rhlist_head      fi_rlist;
        struct list_head        fi_stateids;
        union {
                struct list_head        fi_delegations;
                struct rcu_head         fi_rcu;
        };
        struct list_head        fi_clnt_odstate;
        /* One each for O_RDONLY, O_WRONLY, O_RDWR: */
        struct nfsd_file        *fi_fds[3];
        /*
         * Each open or lock stateid contributes 0-4 to the counts
         * below depending on which bits are set in st_access_bitmap:
         *     1 to fi_access[O_RDONLY] if NFS4_SHARE_ACCES_READ is set
         *   + 1 to fi_access[O_WRONLY] if NFS4_SHARE_ACCESS_WRITE is set
         *   + 1 to both of the above if NFS4_SHARE_ACCESS_BOTH is set.
         */
        atomic_t                fi_access[2];
        u32                     fi_share_deny;
        struct nfsd_file        *fi_deleg_file;
        struct nfsd_file        *fi_rdeleg_file;
        int                     fi_delegees;
        struct knfsd_fh         fi_fhandle;
        bool                    fi_had_conflict;
#ifdef CONFIG_NFSD_PNFS
        struct list_head        fi_lo_states;
        atomic_t                fi_lo_recalls;
#endif
};

/*
 * A generic struct representing either a open or lock stateid. The nfs4_client
 * holds a reference to each of these objects, and they in turn hold a
 * reference to their respective stateowners. The client's reference is
 * released in response to a close or unlock (depending on whether it's an open
 * or lock stateid) or when the client is being destroyed.
 *
 * In the case of v4.0 open stateids, these objects are preserved for a little
 * while after close in order to handle CLOSE replays. Those are eventually
 * reclaimed via a LRU scheme by the laundromat.
 *
 * This object is a superset of the nfs4_stid. "ol" stands for "Open or Lock".
 * Better suggestions welcome.
 */
struct nfs4_ol_stateid {
        struct nfs4_stid                st_stid;
        struct list_head                st_perfile;
        struct list_head                st_perstateowner;
        struct list_head                st_locks;
        struct nfs4_stateowner          *st_stateowner;
        struct nfs4_clnt_odstate        *st_clnt_odstate;
/*
 * These bitmasks use 3 separate bits for READ, ALLOW, and BOTH; see the
 * comment above bmap_to_share_mode() for explanation:
 */
        unsigned char                   st_access_bmap;
        unsigned char                   st_deny_bmap;
        struct nfs4_ol_stateid          *st_openstp;
        struct mutex                    st_mutex;
};

static inline struct nfs4_ol_stateid *openlockstateid(struct nfs4_stid *s)
{
        return container_of(s, struct nfs4_ol_stateid, st_stid);
}

struct nfs4_layout_stateid {
        struct nfs4_stid                ls_stid;
        struct list_head                ls_perclnt;
        struct list_head                ls_perfile;
        spinlock_t                      ls_lock;
        struct list_head                ls_layouts;
        u32                             ls_layout_type;
        struct nfsd_file                *ls_file;
        struct nfsd4_callback           ls_recall;
        stateid_t                       ls_recall_sid;
        bool                            ls_recalled;
        struct mutex                    ls_mutex;
};

static inline struct nfs4_layout_stateid *layoutstateid(struct nfs4_stid *s)
{
        return container_of(s, struct nfs4_layout_stateid, ls_stid);
}

/* flags for preprocess_seqid_op() */
#define RD_STATE                0x00000010
#define WR_STATE                0x00000020

enum nfsd4_cb_op {
        NFSPROC4_CLNT_CB_NULL = 0,
        NFSPROC4_CLNT_CB_RECALL,
        NFSPROC4_CLNT_CB_LAYOUT,
        NFSPROC4_CLNT_CB_OFFLOAD,
        NFSPROC4_CLNT_CB_SEQUENCE,
        NFSPROC4_CLNT_CB_NOTIFY_LOCK,
        NFSPROC4_CLNT_CB_RECALL_ANY,
        NFSPROC4_CLNT_CB_GETATTR,
};

/* Returns true iff a is later than b: */
static inline bool nfsd4_stateid_generation_after(stateid_t *a, stateid_t *b)
{
        return (s32)(a->si_generation - b->si_generation) > 0;
}

/*
 * When a client tries to get a lock on a file, we set one of these objects
 * on the blocking lock. When the lock becomes free, we can then issue a
 * CB_NOTIFY_LOCK to the server.
 */
struct nfsd4_blocked_lock {
        struct list_head        nbl_list;
        struct list_head        nbl_lru;
        time64_t                nbl_time;
        struct file_lock        nbl_lock;
        struct knfsd_fh         nbl_fh;
        struct nfsd4_callback   nbl_cb;
        struct kref             nbl_kref;
};

struct nfsd4_compound_state;
struct nfsd_net;
struct nfsd4_copy;

extern __be32 nfs4_preprocess_stateid_op(struct svc_rqst *rqstp,
                struct nfsd4_compound_state *cstate, struct svc_fh *fhp,
                stateid_t *stateid, int flags, struct nfsd_file **filp,
                struct nfs4_stid **cstid);
__be32 nfsd4_lookup_stateid(struct nfsd4_compound_state *cstate,
                            stateid_t *stateid, unsigned short typemask,
                            unsigned short statusmask,
                            struct nfs4_stid **s, struct nfsd_net *nn);
struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct kmem_cache *slab,
                                  void (*sc_free)(struct nfs4_stid *));
int nfs4_init_copy_state(struct nfsd_net *nn, struct nfsd4_copy *copy);
void nfs4_free_copy_state(struct nfsd4_copy *copy);
struct nfs4_cpntf_state *nfs4_alloc_init_cpntf_state(struct nfsd_net *nn,
                        struct nfs4_stid *p_stid);
void nfs4_put_stid(struct nfs4_stid *s);
void nfs4_inc_and_copy_stateid(stateid_t *dst, struct nfs4_stid *stid);
void nfs4_remove_reclaim_record(struct nfs4_client_reclaim *, struct nfsd_net *);
extern void nfs4_release_reclaim(struct nfsd_net *);
extern struct nfs4_client_reclaim *nfsd4_find_reclaim_client(struct xdr_netobj name,
                                                        struct nfsd_net *nn);
extern __be32 nfs4_check_open_reclaim(struct nfs4_client *);
extern void nfsd4_probe_callback(struct nfs4_client *clp);
extern void nfsd4_probe_callback_sync(struct nfs4_client *clp);
extern void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *);
extern void nfsd41_cb_referring_call(struct nfsd4_callback *cb,
                                     struct nfs4_sessionid *sessionid,
                                     u32 slotid, u32 seqno);
extern void nfsd41_cb_destroy_referring_call_list(struct nfsd4_callback *cb);
extern void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
                const struct nfsd4_callback_ops *ops, enum nfsd4_cb_op op);
extern bool nfsd4_run_cb(struct nfsd4_callback *cb);

static inline void nfsd4_try_run_cb(struct nfsd4_callback *cb)
{
        if (!test_and_set_bit(NFSD4_CALLBACK_RUNNING, &cb->cb_flags))
                WARN_ON_ONCE(!nfsd4_run_cb(cb));
}

extern void nfsd4_shutdown_callback(struct nfs4_client *);
extern void nfsd4_shutdown_copy(struct nfs4_client *clp);
void nfsd4_put_client(struct nfs4_client *clp);
void nfsd4_async_copy_reaper(struct nfsd_net *nn);
bool nfsd4_has_active_async_copies(struct nfs4_client *clp);
extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(struct xdr_netobj name,
                                struct xdr_netobj princhash, struct nfsd_net *nn);
extern bool nfs4_has_reclaimed_state(struct xdr_netobj name, struct nfsd_net *nn);

void put_nfs4_file(struct nfs4_file *fi);
extern void nfs4_put_cpntf_state(struct nfsd_net *nn,
                                 struct nfs4_cpntf_state *cps);
extern __be32 manage_cpntf_state(struct nfsd_net *nn, stateid_t *st,
                                 struct nfs4_client *clp,
                                 struct nfs4_cpntf_state **cps);
static inline void get_nfs4_file(struct nfs4_file *fi)
{
        refcount_inc(&fi->fi_ref);
}
struct nfsd_file *find_any_file(struct nfs4_file *f);

#ifdef CONFIG_NFSD_V4
void nfsd4_revoke_states(struct nfsd_net *nn, struct super_block *sb);
void nfsd4_cancel_copy_by_sb(struct net *net, struct super_block *sb);
#else
static inline void nfsd4_revoke_states(struct nfsd_net *nn, struct super_block *sb)
{
}
static inline void nfsd4_cancel_copy_by_sb(struct net *net, struct super_block *sb)
{
}
#endif

/* grace period management */
bool nfsd4_force_end_grace(struct nfsd_net *nn);

/* nfs4recover operations */
extern int nfsd4_client_tracking_init(struct net *net);
extern void nfsd4_client_tracking_exit(struct net *net);
extern void nfsd4_client_record_create(struct nfs4_client *clp);
extern void nfsd4_client_record_remove(struct nfs4_client *clp);
extern int nfsd4_client_record_check(struct nfs4_client *clp);
extern void nfsd4_record_grace_done(struct nfsd_net *nn);

static inline bool try_to_expire_client(struct nfs4_client *clp)
{
        cmpxchg(&clp->cl_state, NFSD4_COURTESY, NFSD4_EXPIRABLE);
        return clp->cl_state == NFSD4_EXPIRABLE;
}

extern __be32 nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp,
                struct dentry *dentry, struct nfs4_delegation **pdp);

struct nfsd4_get_dir_delegation;
struct nfs4_delegation *nfsd_get_dir_deleg(struct nfsd4_compound_state *cstate,
                                                struct nfsd4_get_dir_delegation *gdd,
                                                struct nfsd_file *nf);
#endif   /* NFSD4_STATE_H */