/*
 * linux/include/linux/sunrpc/svc.h
 *
 * RPC server declarations.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */


#ifndef SUNRPC_SVC_H
#define SUNRPC_SVC_H

#include <linux/in.h>
#include <linux/in6.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/wait.h>
#include <linux/mm.h>

/*
 * This is the RPC server thread function prototype
 */
typedef int             (*svc_thread_fn)(void *);

/* statistics for svc_pool structures */
struct svc_pool_stats {
        unsigned long   packets;
        unsigned long   sockets_queued;
        unsigned long   threads_woken;
        unsigned long   threads_timedout;
};

/*
 *
 * RPC service thread pool.
 *
 * Pool of threads and temporary sockets.  Generally there is only
 * a single one of these per RPC service, but on NUMA machines those
 * services that can benefit from it (i.e. nfs but not lockd) will
 * have one pool per NUMA node.  This optimisation reduces cross-
 * node traffic on multi-node NUMA NFS servers.
 */
struct svc_pool {
        unsigned int            sp_id;          /* pool id; also node id on NUMA */
        spinlock_t              sp_lock;        /* protects all fields */
        struct list_head        sp_threads;     /* idle server threads */
        struct list_head        sp_sockets;     /* pending sockets */
        unsigned int            sp_nrthreads;   /* # of threads in pool */
        struct list_head        sp_all_threads; /* all server threads */
        struct svc_pool_stats   sp_stats;       /* statistics on pool operation */
} ____cacheline_aligned_in_smp;

/*
 * RPC service.
 *
 * An RPC service is a ``daemon,'' possibly multithreaded, which
 * receives and processes incoming RPC messages.
 * It has one or more transport sockets associated with it, and maintains
 * a list of idle threads waiting for input.
 *
 * We currently do not support more than one RPC program per daemon.
 */
struct svc_serv {
        struct svc_program *    sv_program;     /* RPC program */
        struct svc_stat *       sv_stats;       /* RPC statistics */
        spinlock_t              sv_lock;
        unsigned int            sv_nrthreads;   /* # of server threads */
        unsigned int            sv_maxconn;     /* max connections allowed or
                                                 * '0' causing max to be based
                                                 * on number of threads. */

        unsigned int            sv_max_payload; /* datagram payload size */
        unsigned int            sv_max_mesg;    /* max_payload + 1 page for overheads */
        unsigned int            sv_xdrsize;     /* XDR buffer size */
        struct list_head        sv_permsocks;   /* all permanent sockets */
        struct list_head        sv_tempsocks;   /* all temporary sockets */
        int                     sv_tmpcnt;      /* count of temporary sockets */
        struct timer_list       sv_temptimer;   /* timer for aging temporary sockets */

        char *                  sv_name;        /* service name */

        unsigned int            sv_nrpools;     /* number of thread pools */
        struct svc_pool *       sv_pools;       /* array of thread pools */

        void                    (*sv_shutdown)(struct svc_serv *serv);
                                                /* Callback to use when last thread
                                                 * exits.
                                                 */

        struct module *         sv_module;      /* optional module to count when
                                                 * adding threads */
        svc_thread_fn           sv_function;    /* main function for threads */
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
        struct list_head        sv_cb_list;     /* queue for callback requests
                                                 * that arrive over the same
                                                 * connection */
        spinlock_t              sv_cb_lock;     /* protects the svc_cb_list */
        wait_queue_head_t       sv_cb_waitq;    /* sleep here if there are no
                                                 * entries in the svc_cb_list */
        struct svc_xprt         *sv_bc_xprt;    /* callback on fore channel */
#endif /* CONFIG_SUNRPC_BACKCHANNEL */
};

/*
 * We use sv_nrthreads as a reference count.  svc_destroy() drops
 * this refcount, so we need to bump it up around operations that
 * change the number of threads.  Horrible, but there it is.
 * Should be called with the BKL held.
 */
static inline void svc_get(struct svc_serv *serv)
{
        serv->sv_nrthreads++;
}

/*
 * Maximum payload size supported by a kernel RPC server.
 * This is use to determine the max number of pages nfsd is
 * willing to return in a single READ operation.
 *
 * These happen to all be powers of 2, which is not strictly
 * necessary but helps enforce the real limitation, which is
 * that they should be multiples of PAGE_CACHE_SIZE.
 *
 * For UDP transports, a block plus NFS,RPC, and UDP headers
 * has to fit into the IP datagram limit of 64K.  The largest
 * feasible number for all known page sizes is probably 48K,
 * but we choose 32K here.  This is the same as the historical
 * Linux limit; someone who cares more about NFS/UDP performance
 * can test a larger number.
 *
 * For TCP transports we have more freedom.  A size of 1MB is
 * chosen to match the client limit.  Other OSes are known to
 * have larger limits, but those numbers are probably beyond
 * the point of diminishing returns.
 */
#define RPCSVC_MAXPAYLOAD       (1*1024*1024u)
#define RPCSVC_MAXPAYLOAD_TCP   RPCSVC_MAXPAYLOAD
#define RPCSVC_MAXPAYLOAD_UDP   (32*1024u)

extern u32 svc_max_payload(const struct svc_rqst *rqstp);

/*
 * RPC Requsts and replies are stored in one or more pages.
 * We maintain an array of pages for each server thread.
 * Requests are copied into these pages as they arrive.  Remaining
 * pages are available to write the reply into.
 *
 * Pages are sent using ->sendpage so each server thread needs to
 * allocate more to replace those used in sending.  To help keep track
 * of these pages we have a receive list where all pages initialy live,
 * and a send list where pages are moved to when there are to be part
 * of a reply.
 *
 * We use xdr_buf for holding responses as it fits well with NFS
 * read responses (that have a header, and some data pages, and possibly
 * a tail) and means we can share some client side routines.
 *
 * The xdr_buf.head kvec always points to the first page in the rq_*pages
 * list.  The xdr_buf.pages pointer points to the second page on that
 * list.  xdr_buf.tail points to the end of the first page.
 * This assumes that the non-page part of an rpc reply will fit
 * in a page - NFSd ensures this.  lockd also has no trouble.
 *
 * Each request/reply pair can have at most one "payload", plus two pages,
 * one for the request, and one for the reply.
 * We using ->sendfile to return read data, we might need one extra page
 * if the request is not page-aligned.  So add another '1'.
 */
#define RPCSVC_MAXPAGES         ((RPCSVC_MAXPAYLOAD+PAGE_SIZE-1)/PAGE_SIZE \
                                + 2 + 1)

static inline u32 svc_getnl(struct kvec *iov)
{
        __be32 val, *vp;
        vp = iov->iov_base;
        val = *vp++;
        iov->iov_base = (void*)vp;
        iov->iov_len -= sizeof(__be32);
        return ntohl(val);
}

static inline void svc_putnl(struct kvec *iov, u32 val)
{
        __be32 *vp = iov->iov_base + iov->iov_len;
        *vp = htonl(val);
        iov->iov_len += sizeof(__be32);
}

static inline __be32 svc_getu32(struct kvec *iov)
{
        __be32 val, *vp;
        vp = iov->iov_base;
        val = *vp++;
        iov->iov_base = (void*)vp;
        iov->iov_len -= sizeof(__be32);
        return val;
}

static inline void svc_ungetu32(struct kvec *iov)
{
        __be32 *vp = (__be32 *)iov->iov_base;
        iov->iov_base = (void *)(vp - 1);
        iov->iov_len += sizeof(*vp);
}

static inline void svc_putu32(struct kvec *iov, __be32 val)
{
        __be32 *vp = iov->iov_base + iov->iov_len;
        *vp = val;
        iov->iov_len += sizeof(__be32);
}

union svc_addr_u {
    struct in_addr      addr;
    struct in6_addr     addr6;
};

/*
 * The context of a single thread, including the request currently being
 * processed.
 */
struct svc_rqst {
        struct list_head        rq_list;        /* idle list */
        struct list_head        rq_all;         /* all threads list */
        struct svc_xprt *       rq_xprt;        /* transport ptr */
        struct sockaddr_storage rq_addr;        /* peer address */
        size_t                  rq_addrlen;

        struct svc_serv *       rq_server;      /* RPC service definition */
        struct svc_pool *       rq_pool;        /* thread pool */
        struct svc_procedure *  rq_procinfo;    /* procedure info */
        struct auth_ops *       rq_authop;      /* authentication flavour */
        u32                     rq_flavor;      /* pseudoflavor */
        struct svc_cred         rq_cred;        /* auth info */
        void *                  rq_xprt_ctxt;   /* transport specific context ptr */
        struct svc_deferred_req*rq_deferred;    /* deferred request we are replaying */
        int                     rq_usedeferral; /* use deferral */

        size_t                  rq_xprt_hlen;   /* xprt header len */
        struct xdr_buf          rq_arg;
        struct xdr_buf          rq_res;
        struct page *           rq_pages[RPCSVC_MAXPAGES];
        struct page *           *rq_respages;   /* points into rq_pages */
        int                     rq_resused;     /* number of pages used for result */

        struct kvec             rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */

        __be32                  rq_xid;         /* transmission id */
        u32                     rq_prog;        /* program number */
        u32                     rq_vers;        /* program version */
        u32                     rq_proc;        /* procedure number */
        u32                     rq_prot;        /* IP protocol */
        unsigned short
                                rq_secure  : 1; /* secure port */

        union svc_addr_u        rq_daddr;       /* dest addr of request
                                                 *  - reply from here */

        void *                  rq_argp;        /* decoded arguments */
        void *                  rq_resp;        /* xdr'd results */
        void *                  rq_auth_data;   /* flavor-specific data */

        int                     rq_reserved;    /* space on socket outq
                                                 * reserved for this request
                                                 */

        struct cache_req        rq_chandle;     /* handle passed to caches for 
                                                 * request delaying 
                                                 */
        bool                    rq_dropme;
        /* Catering to nfsd */
        struct auth_domain *    rq_client;      /* RPC peer info */
        struct auth_domain *    rq_gssclient;   /* "gss/"-style peer info */
        int                     rq_cachetype;
        struct svc_cacherep *   rq_cacherep;    /* cache info */
        int                     rq_splice_ok;   /* turned off in gss privacy
                                                 * to prevent encrypting page
                                                 * cache pages */
        wait_queue_head_t       rq_wait;        /* synchronization */
        struct task_struct      *rq_task;       /* service thread */
};

/*
 * Rigorous type checking on sockaddr type conversions
 */
static inline struct sockaddr_in *svc_addr_in(const struct svc_rqst *rqst)
{
        return (struct sockaddr_in *) &rqst->rq_addr;
}

static inline struct sockaddr_in6 *svc_addr_in6(const struct svc_rqst *rqst)
{
        return (struct sockaddr_in6 *) &rqst->rq_addr;
}

static inline struct sockaddr *svc_addr(const struct svc_rqst *rqst)
{
        return (struct sockaddr *) &rqst->rq_addr;
}

/*
 * Check buffer bounds after decoding arguments
 */
static inline int
xdr_argsize_check(struct svc_rqst *rqstp, __be32 *p)
{
        char *cp = (char *)p;
        struct kvec *vec = &rqstp->rq_arg.head[0];
        return cp >= (char*)vec->iov_base
                && cp <= (char*)vec->iov_base + vec->iov_len;
}

static inline int
xdr_ressize_check(struct svc_rqst *rqstp, __be32 *p)
{
        struct kvec *vec = &rqstp->rq_res.head[0];
        char *cp = (char*)p;

        vec->iov_len = cp - (char*)vec->iov_base;

        return vec->iov_len <= PAGE_SIZE;
}

static inline void svc_free_res_pages(struct svc_rqst *rqstp)
{
        while (rqstp->rq_resused) {
                struct page **pp = (rqstp->rq_respages +
                                    --rqstp->rq_resused);
                if (*pp) {
                        put_page(*pp);
                        *pp = NULL;
                }
        }
}

struct svc_deferred_req {
        u32                     prot;   /* protocol (UDP or TCP) */
        struct svc_xprt         *xprt;
        struct sockaddr_storage addr;   /* where reply must go */
        size_t                  addrlen;
        union svc_addr_u        daddr;  /* where reply must come from */
        struct cache_deferred_req handle;
        size_t                  xprt_hlen;
        int                     argslen;
        __be32                  args[0];
};

/*
 * List of RPC programs on the same transport endpoint
 */
struct svc_program {
        struct svc_program *    pg_next;        /* other programs (same xprt) */
        u32                     pg_prog;        /* program number */
        unsigned int            pg_lovers;      /* lowest version */
        unsigned int            pg_hivers;      /* lowest version */
        unsigned int            pg_nvers;       /* number of versions */
        struct svc_version **   pg_vers;        /* version array */
        char *                  pg_name;        /* service name */
        char *                  pg_class;       /* class name: services sharing authentication */
        struct svc_stat *       pg_stats;       /* rpc statistics */
        int                     (*pg_authenticate)(struct svc_rqst *);
};

/*
 * RPC program version
 */
struct svc_version {
        u32                     vs_vers;        /* version number */
        u32                     vs_nproc;       /* number of procedures */
        struct svc_procedure *  vs_proc;        /* per-procedure info */
        u32                     vs_xdrsize;     /* xdrsize needed for this version */

        unsigned int            vs_hidden : 1;  /* Don't register with portmapper.
                                                 * Only used for nfsacl so far. */

        /* Override dispatch function (e.g. when caching replies).
         * A return value of 0 means drop the request. 
         * vs_dispatch == NULL means use default dispatcher.
         */
        int                     (*vs_dispatch)(struct svc_rqst *, __be32 *);
};

/*
 * RPC procedure info
 */
typedef __be32  (*svc_procfunc)(struct svc_rqst *, void *argp, void *resp);
struct svc_procedure {
        svc_procfunc            pc_func;        /* process the request */
        kxdrproc_t              pc_decode;      /* XDR decode args */
        kxdrproc_t              pc_encode;      /* XDR encode result */
        kxdrproc_t              pc_release;     /* XDR free result */
        unsigned int            pc_argsize;     /* argument struct size */
        unsigned int            pc_ressize;     /* result struct size */
        unsigned int            pc_count;       /* call count */
        unsigned int            pc_cachetype;   /* cache info (NFS) */
        unsigned int            pc_xdrressize;  /* maximum size of XDR reply */
};

/*
 * Function prototypes.
 */
struct svc_serv *svc_create(struct svc_program *, unsigned int,
                            void (*shutdown)(struct svc_serv *));
struct svc_rqst *svc_prepare_thread(struct svc_serv *serv,
                                        struct svc_pool *pool);
void               svc_exit_thread(struct svc_rqst *);
struct svc_serv *  svc_create_pooled(struct svc_program *, unsigned int,
                        void (*shutdown)(struct svc_serv *),
                        svc_thread_fn, struct module *);
int                svc_set_num_threads(struct svc_serv *, struct svc_pool *, int);
int                svc_pool_stats_open(struct svc_serv *serv, struct file *file);
void               svc_destroy(struct svc_serv *);
int                svc_process(struct svc_rqst *);
int                bc_svc_process(struct svc_serv *, struct rpc_rqst *,
                        struct svc_rqst *);
int                svc_register(const struct svc_serv *, const int,
                                const unsigned short, const unsigned short);

void               svc_wake_up(struct svc_serv *);
void               svc_reserve(struct svc_rqst *rqstp, int space);
struct svc_pool *  svc_pool_for_cpu(struct svc_serv *serv, int cpu);
char *             svc_print_addr(struct svc_rqst *, char *, size_t);

#define RPC_MAX_ADDRBUFLEN      (63U)

/*
 * When we want to reduce the size of the reserved space in the response
 * buffer, we need to take into account the size of any checksum data that
 * may be at the end of the packet. This is difficult to determine exactly
 * for all cases without actually generating the checksum, so we just use a
 * static value.
 */
static inline void svc_reserve_auth(struct svc_rqst *rqstp, int space)
{
        int added_space = 0;

        if (rqstp->rq_authop->flavour)
                added_space = RPC_MAX_AUTH_SIZE;
        svc_reserve(rqstp, space + added_space);
}

#endif /* SUNRPC_SVC_H */