/* SPDX-License-Identifier: GPL-2.0 */
/*
 *  linux/include/linux/sunrpc/xprt.h
 *
 *  Declarations for the RPC transport interface.
 *
 *  Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#ifndef _LINUX_SUNRPC_XPRT_H
#define _LINUX_SUNRPC_XPRT_H

#include <linux/uio.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/ktime.h>
#include <linux/kref.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/msg_prot.h>

#define RPC_MIN_SLOT_TABLE      (2U)
#define RPC_DEF_SLOT_TABLE      (16U)
#define RPC_MAX_SLOT_TABLE_LIMIT        (65536U)
#define RPC_MAX_SLOT_TABLE      RPC_MAX_SLOT_TABLE_LIMIT

#define RPC_CWNDSHIFT           (8U)
#define RPC_CWNDSCALE           (1U << RPC_CWNDSHIFT)
#define RPC_INITCWND            RPC_CWNDSCALE
#define RPC_MAXCWND(xprt)       ((xprt)->max_reqs << RPC_CWNDSHIFT)
#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)

#define RPC_GSS_SEQNO_ARRAY_SIZE 3U

enum rpc_display_format_t {
        RPC_DISPLAY_ADDR = 0,
        RPC_DISPLAY_PORT,
        RPC_DISPLAY_PROTO,
        RPC_DISPLAY_HEX_ADDR,
        RPC_DISPLAY_HEX_PORT,
        RPC_DISPLAY_NETID,
        RPC_DISPLAY_MAX,
};

struct rpc_task;
struct rpc_xprt;
struct xprt_class;
struct seq_file;
struct svc_serv;
struct net;
#include <linux/lwq.h>

/*
 * This describes a complete RPC request
 */
struct rpc_rqst {
        /*
         * This is the user-visible part
         */
        struct rpc_xprt *       rq_xprt;                /* RPC client */
        struct xdr_buf          rq_snd_buf;             /* send buffer */
        struct xdr_buf          rq_rcv_buf;             /* recv buffer */

        /*
         * This is the private part
         */
        struct rpc_task *       rq_task;        /* RPC task data */
        struct rpc_cred *       rq_cred;        /* Bound cred */
        __be32                  rq_xid;         /* request XID */
        int                     rq_cong;        /* has incremented xprt->cong */
        u32                     rq_seqnos[RPC_GSS_SEQNO_ARRAY_SIZE];    /* past gss req seq nos. */
        unsigned int            rq_seqno_count; /* number of entries in rq_seqnos */
        int                     rq_enc_pages_num;
        struct page             **rq_enc_pages; /* scratch pages for use by
                                                   gss privacy code */
        void (*rq_release_snd_buf)(struct rpc_rqst *); /* release rq_enc_pages */

        union {
                struct list_head        rq_list;        /* Slot allocation list */
                struct rb_node          rq_recv;        /* Receive queue */
        };

        struct list_head        rq_xmit;        /* Send queue */
        struct list_head        rq_xmit2;       /* Send queue */

        void                    *rq_buffer;     /* Call XDR encode buffer */
        size_t                  rq_callsize;
        void                    *rq_rbuffer;    /* Reply XDR decode buffer */
        size_t                  rq_rcvsize;
        size_t                  rq_xmit_bytes_sent;     /* total bytes sent */
        size_t                  rq_reply_bytes_recvd;   /* total reply bytes */
                                                        /* received */

        struct xdr_buf          rq_private_buf;         /* The receive buffer
                                                         * used in the softirq.
                                                         */
        unsigned long           rq_majortimeo;  /* major timeout alarm */
        unsigned long           rq_minortimeo;  /* minor timeout alarm */
        unsigned long           rq_timeout;     /* Current timeout value */
        ktime_t                 rq_rtt;         /* round-trip time */
        unsigned int            rq_retries;     /* # of retries */
        unsigned int            rq_connect_cookie;
                                                /* A cookie used to track the
                                                   state of the transport
                                                   connection */
        atomic_t                rq_pin;
        
        /*
         * Partial send handling
         */
        u32                     rq_bytes_sent;  /* Bytes we have sent */

        ktime_t                 rq_xtime;       /* transmit time stamp */
        int                     rq_ntrans;

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
        struct lwq_node         rq_bc_list;     /* Callback service list */
        unsigned long           rq_bc_pa_state; /* Backchannel prealloc state */
        struct list_head        rq_bc_pa_list;  /* Backchannel prealloc list */
#endif /* CONFIG_SUNRPC_BACKCHANEL */
};
#define rq_svec                 rq_snd_buf.head
#define rq_slen                 rq_snd_buf.len

static inline int xprt_rqst_add_seqno(struct rpc_rqst *req, u32 seqno)
{
        if (likely(req->rq_seqno_count < RPC_GSS_SEQNO_ARRAY_SIZE))
                req->rq_seqno_count++;

        /* Shift array to make room for the newest element at the beginning */
        memmove(&req->rq_seqnos[1], &req->rq_seqnos[0],
                (RPC_GSS_SEQNO_ARRAY_SIZE - 1) * sizeof(req->rq_seqnos[0]));
        req->rq_seqnos[0] = seqno;
        return 0;
}

/* RPC transport layer security policies */
enum xprtsec_policies {
        RPC_XPRTSEC_NONE = 0,
        RPC_XPRTSEC_TLS_ANON,
        RPC_XPRTSEC_TLS_X509,
};

struct xprtsec_parms {
        enum xprtsec_policies   policy;

        /* authentication material */
        key_serial_t            cert_serial;
        key_serial_t            privkey_serial;
};

struct rpc_xprt_ops {
        void            (*set_buffer_size)(struct rpc_xprt *xprt, size_t sndsize, size_t rcvsize);
        int             (*reserve_xprt)(struct rpc_xprt *xprt, struct rpc_task *task);
        void            (*release_xprt)(struct rpc_xprt *xprt, struct rpc_task *task);
        void            (*alloc_slot)(struct rpc_xprt *xprt, struct rpc_task *task);
        void            (*free_slot)(struct rpc_xprt *xprt,
                                     struct rpc_rqst *req);
        void            (*rpcbind)(struct rpc_task *task);
        void            (*set_port)(struct rpc_xprt *xprt, unsigned short port);
        void            (*connect)(struct rpc_xprt *xprt, struct rpc_task *task);
        int             (*get_srcaddr)(struct rpc_xprt *xprt, char *buf,
                                       size_t buflen);
        unsigned short  (*get_srcport)(struct rpc_xprt *xprt);
        int             (*buf_alloc)(struct rpc_task *task);
        void            (*buf_free)(struct rpc_task *task);
        int             (*prepare_request)(struct rpc_rqst *req,
                                           struct xdr_buf *buf);
        int             (*send_request)(struct rpc_rqst *req);
        void            (*abort_send_request)(struct rpc_rqst *req);
        void            (*wait_for_reply_request)(struct rpc_task *task);
        void            (*timer)(struct rpc_xprt *xprt, struct rpc_task *task);
        void            (*release_request)(struct rpc_task *task);
        void            (*close)(struct rpc_xprt *xprt);
        void            (*destroy)(struct rpc_xprt *xprt);
        void            (*set_connect_timeout)(struct rpc_xprt *xprt,
                                        unsigned long connect_timeout,
                                        unsigned long reconnect_timeout);
        void            (*print_stats)(struct rpc_xprt *xprt, struct seq_file *seq);
        int             (*enable_swap)(struct rpc_xprt *xprt);
        void            (*disable_swap)(struct rpc_xprt *xprt);
        void            (*inject_disconnect)(struct rpc_xprt *xprt);
        int             (*bc_setup)(struct rpc_xprt *xprt,
                                    unsigned int min_reqs);
        size_t          (*bc_maxpayload)(struct rpc_xprt *xprt);
        unsigned int    (*bc_num_slots)(struct rpc_xprt *xprt);
        void            (*bc_free_rqst)(struct rpc_rqst *rqst);
        void            (*bc_destroy)(struct rpc_xprt *xprt,
                                      unsigned int max_reqs);
};

/*
 * RPC transport identifiers
 *
 * To preserve compatibility with the historical use of raw IP protocol
 * id's for transport selection, UDP and TCP identifiers are specified
 * with the previous values. No such restriction exists for new transports,
 * except that they may not collide with these values (17 and 6,
 * respectively).
 */
#define XPRT_TRANSPORT_BC       (1 << 31)
enum xprt_transports {
        XPRT_TRANSPORT_UDP      = IPPROTO_UDP,
        XPRT_TRANSPORT_TCP      = IPPROTO_TCP,
        XPRT_TRANSPORT_BC_TCP   = IPPROTO_TCP | XPRT_TRANSPORT_BC,
        XPRT_TRANSPORT_RDMA     = 256,
        XPRT_TRANSPORT_BC_RDMA  = XPRT_TRANSPORT_RDMA | XPRT_TRANSPORT_BC,
        XPRT_TRANSPORT_LOCAL    = 257,
        XPRT_TRANSPORT_TCP_TLS  = 258,
};

struct rpc_sysfs_xprt;
struct rpc_xprt {
        struct kref             kref;           /* Reference count */
        const struct rpc_xprt_ops *ops;         /* transport methods */
        unsigned int            id;             /* transport id */

        const struct rpc_timeout *timeout;      /* timeout parms */
        struct sockaddr_storage addr;           /* server address */
        size_t                  addrlen;        /* size of server address */
        int                     prot;           /* IP protocol */

        unsigned long           cong;           /* current congestion */
        unsigned long           cwnd;           /* congestion window */

        size_t                  max_payload;    /* largest RPC payload size,
                                                   in bytes */

        struct rpc_wait_queue   binding;        /* requests waiting on rpcbind */
        struct rpc_wait_queue   sending;        /* requests waiting to send */
        struct rpc_wait_queue   pending;        /* requests in flight */
        struct rpc_wait_queue   backlog;        /* waiting for slot */
        struct list_head        free;           /* free slots */
        unsigned int            max_reqs;       /* max number of slots */
        unsigned int            min_reqs;       /* min number of slots */
        unsigned int            num_reqs;       /* total slots */
        unsigned long           state;          /* transport state */
        unsigned char           resvport   : 1, /* use a reserved port */
                                reuseport  : 1; /* reuse port on reconnect */
        atomic_t                swapper;        /* we're swapping over this
                                                   transport */
        unsigned int            bind_index;     /* bind function index */

        /*
         * Multipath
         */
        struct list_head        xprt_switch;

        /*
         * Connection of transports
         */
        unsigned long           bind_timeout,
                                reestablish_timeout;
        struct xprtsec_parms    xprtsec;
        unsigned int            connect_cookie; /* A cookie that gets bumped
                                                   every time the transport
                                                   is reconnected */

        /*
         * Disconnection of idle transports
         */
        struct work_struct      task_cleanup;
        struct timer_list       timer;
        unsigned long           last_used,
                                idle_timeout,
                                connect_timeout,
                                max_reconnect_timeout;

        /*
         * Send stuff
         */
        atomic_long_t           queuelen;
        spinlock_t              transport_lock; /* lock transport info */
        spinlock_t              reserve_lock;   /* lock slot table */
        spinlock_t              queue_lock;     /* send/receive queue lock */
        u32                     xid;            /* Next XID value to use */
        struct rpc_task *       snd_task;       /* Task blocked in send */

        struct list_head        xmit_queue;     /* Send queue */
        atomic_long_t           xmit_queuelen;

        struct svc_xprt         *bc_xprt;       /* NFSv4.1 backchannel */
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
        struct svc_serv         *bc_serv;       /* The RPC service which will */
                                                /* process the callback */
        unsigned int            bc_alloc_max;
        unsigned int            bc_alloc_count; /* Total number of preallocs */
        atomic_t                bc_slot_count;  /* Number of allocated slots */
        spinlock_t              bc_pa_lock;     /* Protects the preallocated
                                                 * items */
        struct list_head        bc_pa_list;     /* List of preallocated
                                                 * backchannel rpc_rqst's */
#endif /* CONFIG_SUNRPC_BACKCHANNEL */

        struct rb_root          recv_queue;     /* Receive queue */

        struct {
                unsigned long           bind_count,     /* total number of binds */
                                        connect_count,  /* total number of connects */
                                        connect_start,  /* connect start timestamp */
                                        connect_time,   /* jiffies waiting for connect */
                                        sends,          /* how many complete requests */
                                        recvs,          /* how many complete requests */
                                        bad_xids,       /* lookup_rqst didn't find XID */
                                        max_slots;      /* max rpc_slots used */

                unsigned long long      req_u,          /* average requests on the wire */
                                        bklog_u,        /* backlog queue utilization */
                                        sending_u,      /* send q utilization */
                                        pending_u;      /* pend q utilization */
        } stat;

        struct net              *xprt_net;
        netns_tracker           ns_tracker;
        const char              *servername;
        const char              *address_strings[RPC_DISPLAY_MAX];
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
        struct dentry           *debugfs;               /* debugfs directory */
#endif
        struct rcu_head         rcu;
        const struct xprt_class *xprt_class;
        struct rpc_sysfs_xprt   *xprt_sysfs;
        bool                    main; /*mark if this is the 1st transport */
};

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
/*
 * Backchannel flags
 */
#define RPC_BC_PA_IN_USE        0x0001          /* Preallocated backchannel */
                                                /* buffer in use */
#endif /* CONFIG_SUNRPC_BACKCHANNEL */

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
static inline int bc_prealloc(struct rpc_rqst *req)
{
        return test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
}
#else
static inline int bc_prealloc(struct rpc_rqst *req)
{
        return 0;
}
#endif /* CONFIG_SUNRPC_BACKCHANNEL */

#define XPRT_CREATE_INFINITE_SLOTS      (1U)
#define XPRT_CREATE_NO_IDLE_TIMEOUT     (1U << 1)

struct xprt_create {
        int                     ident;          /* XPRT_TRANSPORT identifier */
        struct net *            net;
        struct sockaddr *       srcaddr;        /* optional local address */
        struct sockaddr *       dstaddr;        /* remote peer address */
        size_t                  addrlen;
        const char              *servername;
        struct svc_xprt         *bc_xprt;       /* NFSv4.1 backchannel */
        struct rpc_xprt_switch  *bc_xps;
        unsigned int            flags;
        struct xprtsec_parms    xprtsec;
        unsigned long           connect_timeout;
        unsigned long           reconnect_timeout;
};

struct xprt_class {
        struct list_head        list;
        int                     ident;          /* XPRT_TRANSPORT identifier */
        struct rpc_xprt *       (*setup)(struct xprt_create *);
        struct module           *owner;
        char                    name[32];
        const char *            netid[];
};

/*
 * Generic internal transport functions
 */
struct rpc_xprt         *xprt_create_transport(struct xprt_create *args);
void                    xprt_connect(struct rpc_task *task);
unsigned long           xprt_reconnect_delay(const struct rpc_xprt *xprt);
void                    xprt_reconnect_backoff(struct rpc_xprt *xprt,
                                               unsigned long init_to);
void                    xprt_reserve(struct rpc_task *task);
void                    xprt_retry_reserve(struct rpc_task *task);
int                     xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
int                     xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);
void                    xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task);
void                    xprt_free_slot(struct rpc_xprt *xprt,
                                       struct rpc_rqst *req);
bool                    xprt_prepare_transmit(struct rpc_task *task);
void                    xprt_request_enqueue_transmit(struct rpc_task *task);
int                     xprt_request_enqueue_receive(struct rpc_task *task);
void                    xprt_request_wait_receive(struct rpc_task *task);
void                    xprt_request_dequeue_xprt(struct rpc_task *task);
bool                    xprt_request_need_retransmit(struct rpc_task *task);
void                    xprt_transmit(struct rpc_task *task);
void                    xprt_end_transmit(struct rpc_task *task);
int                     xprt_adjust_timeout(struct rpc_rqst *req);
void                    xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
void                    xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);
void                    xprt_release(struct rpc_task *task);
struct rpc_xprt *       xprt_get(struct rpc_xprt *xprt);
void                    xprt_put(struct rpc_xprt *xprt);
struct rpc_xprt *       xprt_alloc(struct net *net, size_t size,
                                unsigned int num_prealloc,
                                unsigned int max_req);
void                    xprt_free(struct rpc_xprt *);
void                    xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task);
bool                    xprt_wake_up_backlog(struct rpc_xprt *xprt, struct rpc_rqst *req);
void                    xprt_cleanup_ids(void);

static inline int
xprt_enable_swap(struct rpc_xprt *xprt)
{
        return xprt->ops->enable_swap(xprt);
}

static inline void
xprt_disable_swap(struct rpc_xprt *xprt)
{
        xprt->ops->disable_swap(xprt);
}

/*
 * Transport switch helper functions
 */
int                     xprt_register_transport(struct xprt_class *type);
int                     xprt_unregister_transport(struct xprt_class *type);
int                     xprt_find_transport_ident(const char *);
void                    xprt_wait_for_reply_request_def(struct rpc_task *task);
void                    xprt_wait_for_reply_request_rtt(struct rpc_task *task);
void                    xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status);
void                    xprt_wait_for_buffer_space(struct rpc_xprt *xprt);
bool                    xprt_write_space(struct rpc_xprt *xprt);
void                    xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result);
struct rpc_rqst *       xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid);
void                    xprt_update_rtt(struct rpc_task *task);
void                    xprt_complete_rqst(struct rpc_task *task, int copied);
void                    xprt_pin_rqst(struct rpc_rqst *req);
void                    xprt_unpin_rqst(struct rpc_rqst *req);
void                    xprt_release_rqst_cong(struct rpc_task *task);
bool                    xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req);
void                    xprt_disconnect_done(struct rpc_xprt *xprt);
void                    xprt_force_disconnect(struct rpc_xprt *xprt);
void                    xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie);

bool                    xprt_lock_connect(struct rpc_xprt *, struct rpc_task *, void *);
void                    xprt_unlock_connect(struct rpc_xprt *, void *);
void                    xprt_release_write(struct rpc_xprt *, struct rpc_task *);

/*
 * Reserved bit positions in xprt->state
 */
#define XPRT_LOCKED             (0)
#define XPRT_CONNECTED          (1)
#define XPRT_CONNECTING         (2)
#define XPRT_CLOSE_WAIT         (3)
#define XPRT_BOUND              (4)
#define XPRT_BINDING            (5)
#define XPRT_CLOSING            (6)
#define XPRT_OFFLINE            (7)
#define XPRT_REMOVE             (8)
#define XPRT_CONGESTED          (9)
#define XPRT_CWND_WAIT          (10)
#define XPRT_WRITE_SPACE        (11)
#define XPRT_SND_IS_COOKIE      (12)

static inline void xprt_set_connected(struct rpc_xprt *xprt)
{
        set_bit(XPRT_CONNECTED, &xprt->state);
}

static inline void xprt_clear_connected(struct rpc_xprt *xprt)
{
        clear_bit(XPRT_CONNECTED, &xprt->state);
}

static inline int xprt_connected(struct rpc_xprt *xprt)
{
        return test_bit(XPRT_CONNECTED, &xprt->state);
}

static inline int xprt_test_and_set_connected(struct rpc_xprt *xprt)
{
        return test_and_set_bit(XPRT_CONNECTED, &xprt->state);
}

static inline int xprt_test_and_clear_connected(struct rpc_xprt *xprt)
{
        return test_and_clear_bit(XPRT_CONNECTED, &xprt->state);
}

static inline void xprt_clear_connecting(struct rpc_xprt *xprt)
{
        smp_mb__before_atomic();
        clear_bit(XPRT_CONNECTING, &xprt->state);
        smp_mb__after_atomic();
}

static inline int xprt_connecting(struct rpc_xprt *xprt)
{
        return test_bit(XPRT_CONNECTING, &xprt->state);
}

static inline int xprt_test_and_set_connecting(struct rpc_xprt *xprt)
{
        return test_and_set_bit(XPRT_CONNECTING, &xprt->state);
}

static inline void xprt_set_bound(struct rpc_xprt *xprt)
{
        test_and_set_bit(XPRT_BOUND, &xprt->state);
}

static inline int xprt_bound(struct rpc_xprt *xprt)
{
        return test_bit(XPRT_BOUND, &xprt->state);
}

static inline void xprt_clear_bound(struct rpc_xprt *xprt)
{
        clear_bit(XPRT_BOUND, &xprt->state);
}

static inline void xprt_clear_binding(struct rpc_xprt *xprt)
{
        smp_mb__before_atomic();
        clear_bit(XPRT_BINDING, &xprt->state);
        smp_mb__after_atomic();
}

static inline int xprt_test_and_set_binding(struct rpc_xprt *xprt)
{
        return test_and_set_bit(XPRT_BINDING, &xprt->state);
}

void xprt_set_offline_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps);
void xprt_set_online_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps);
void xprt_delete_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps);
#endif /* _LINUX_SUNRPC_XPRT_H */