/* SPDX-License-Identifier: GPL-2.0 */
/*
 * 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/lwq.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/pagevec.h>
#include <linux/kthread.h>

/*
 *
 * 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 */
        unsigned int            sp_nrthreads;   /* # of threads currently running in pool */
        unsigned int            sp_nrthrmin;    /* Min number of threads to run per pool */
        unsigned int            sp_nrthrmax;    /* Max requested number of threads in pool */
        struct lwq              sp_xprts;       /* pending transports */
        struct list_head        sp_all_threads; /* all server threads */
        struct llist_head       sp_idle_threads; /* idle server threads */

        /* statistics on pool operation */
        struct percpu_counter   sp_messages_arrived;
        struct percpu_counter   sp_sockets_queued;
        struct percpu_counter   sp_threads_woken;

        unsigned long           sp_flags;
} ____cacheline_aligned_in_smp;

/* bits for sp_flags */
enum {
        SP_TASK_PENDING,        /* still work to do even if no xprt is queued */
        SP_NEED_VICTIM,         /* One thread needs to agree to exit */
        SP_VICTIM_REMAINS,      /* One thread needs to actually exit */
        SP_TASK_STARTING,       /* Task has started but not added to idle yet */
};


/*
 * 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_programs;    /* RPC programs */
        struct svc_stat *       sv_stats;       /* RPC statistics */
        spinlock_t              sv_lock;
        unsigned int            sv_nprogs;      /* Number of sv_programs */
        unsigned int            sv_nrthreads;   /* # of running server 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 "valid" sockets */
        struct timer_list       sv_temptimer;   /* timer for aging temporary sockets */

        char *                  sv_name;        /* service name */

        unsigned int            sv_nrpools;     /* number of thread pools */
        bool                    sv_is_pooled;   /* is this a pooled service? */
        struct svc_pool *       sv_pools;       /* array of thread pools */
        int                     (*sv_threadfn)(void *data);

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
        struct lwq              sv_cb_list;     /* queue for callback requests
                                                 * that arrive over the same
                                                 * connection */
        bool                    sv_bc_enabled;  /* service uses backchannel */
#endif /* CONFIG_SUNRPC_BACKCHANNEL */
};

/* This is used by pool_stats to find and lock an svc */
struct svc_info {
        struct svc_serv         *serv;
        struct mutex            *mutex;
};

void svc_destroy(struct svc_serv **svcp);

/*
 * 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_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 non-UDP transports we have more freedom.  A size of 4MB is
 * chosen to accommodate clients that support larger I/O sizes.
 */
enum {
        RPCSVC_MAXPAYLOAD       = 4 * 1024 * 1024,
        RPCSVC_MAXPAYLOAD_TCP   = RPCSVC_MAXPAYLOAD,
        RPCSVC_MAXPAYLOAD_UDP   = 32 * 1024,
};

extern u32 svc_max_payload(const struct svc_rqst *rqstp);

/*
 * RPC Requests 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 ->sendmsg with MSG_SPLICE_PAGES 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.
 */

/**
 * svc_serv_maxpages - maximum count of pages needed for one RPC message
 * @serv: RPC service context
 *
 * Returns a count of pages or vectors that can hold the maximum
 * size RPC message for @serv.
 *
 * Each request/reply pair can have at most one "payload", plus two
 * pages, one for the request, and one for the reply.
 * nfsd_splice_actor() might need an extra page when a READ payload
 * is not page-aligned.
 */
static inline unsigned long svc_serv_maxpages(const struct svc_serv *serv)
{
        return DIV_ROUND_UP(serv->sv_max_mesg, PAGE_SIZE) + 2 + 1;
}

/*
 * The context of a single thread, including the request currently being
 * processed.
 */
struct svc_rqst {
        struct list_head        rq_all;         /* all threads list */
        struct llist_node       rq_idle;        /* On the idle list */
        struct rcu_head         rq_rcu_head;    /* for RCU deferred kfree */
        struct svc_xprt *       rq_xprt;        /* transport ptr */

        struct sockaddr_storage rq_addr;        /* peer address */
        size_t                  rq_addrlen;
        struct sockaddr_storage rq_daddr;       /* dest addr of request
                                                 *  - reply from here */
        size_t                  rq_daddrlen;

        struct svc_serv *       rq_server;      /* RPC service definition */
        struct svc_pool *       rq_pool;        /* thread pool */
        const struct svc_procedure *rq_procinfo;/* procedure info */
        struct auth_ops *       rq_authop;      /* authentication flavour */
        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 */

        struct xdr_buf          rq_arg;
        struct xdr_stream       rq_arg_stream;
        struct xdr_stream       rq_res_stream;
        struct folio            *rq_scratch_folio;
        struct xdr_buf          rq_res;
        unsigned long           rq_maxpages;    /* num of entries in rq_pages */
        struct page *           *rq_pages;
        struct page *           *rq_respages;   /* points into rq_pages */
        struct page *           *rq_next_page; /* next reply page to use */
        struct page *           *rq_page_end;  /* one past the last page */

        struct folio_batch      rq_fbatch;
        struct bio_vec          *rq_bvec;

        __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 */
        int                     rq_cachetype;   /* catering to nfsd */
        unsigned long           rq_flags;       /* flags field */
        ktime_t                 rq_qtime;       /* enqueue time */

        void *                  rq_argp;        /* decoded arguments */
        void *                  rq_resp;        /* xdr'd results */
        __be32                  *rq_accept_statp;
        void *                  rq_auth_data;   /* flavor-specific data */
        __be32                  rq_auth_stat;   /* authentication status */
        int                     rq_auth_slack;  /* extra space xdr code
                                                 * should leave in head
                                                 * for krb5i, krb5p.
                                                 */
        int                     rq_reserved;    /* space on socket outq
                                                 * reserved for this request
                                                 */
        ktime_t                 rq_stime;       /* start time */

        struct cache_req        rq_chandle;     /* handle passed to caches for 
                                                 * request delaying 
                                                 */
        /* Catering to nfsd */
        struct auth_domain *    rq_client;      /* RPC peer info */
        struct auth_domain *    rq_gssclient;   /* "gss/"-style peer info */
        struct task_struct      *rq_task;       /* service thread */
        struct net              *rq_bc_net;     /* pointer to backchannel's
                                                 * net namespace
                                                 */

        int                     rq_err;         /* Thread sets this to inidicate
                                                 * initialisation success.
                                                 */

        unsigned long           bc_to_initval;
        unsigned int            bc_to_retries;
        unsigned int            rq_status_counter; /* RPC processing counter */
        void                    **rq_lease_breaker; /* The v4 client breaking a lease */
};

/* bits for rq_flags */
enum {
        RQ_SECURE,              /* secure port */
        RQ_LOCAL,               /* local request */
        RQ_USEDEFERRAL,         /* use deferral */
        RQ_DROPME,              /* drop current reply */
        RQ_VICTIM,              /* Have agreed to shut down */
        RQ_DATA,                /* request has data */
};

#define SVC_NET(rqst) (rqst->rq_xprt ? rqst->rq_xprt->xpt_net : rqst->rq_bc_net)

/*
 * 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;
}

static inline struct sockaddr_in *svc_daddr_in(const struct svc_rqst *rqst)
{
        return (struct sockaddr_in *) &rqst->rq_daddr;
}

static inline struct sockaddr_in6 *svc_daddr_in6(const struct svc_rqst *rqst)
{
        return (struct sockaddr_in6 *) &rqst->rq_daddr;
}

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

/**
 * svc_thread_should_stop - check if this thread should stop
 * @rqstp: the thread that might need to stop
 *
 * To stop an svc thread, the pool flags SP_NEED_VICTIM and SP_VICTIM_REMAINS
 * are set.  The first thread which sees SP_NEED_VICTIM clears it, becoming
 * the victim using this function.  It should then promptly call
 * svc_exit_thread() to complete the process, clearing SP_VICTIM_REMAINS
 * so the task waiting for a thread to exit can wake and continue.
 *
 * Return values:
 *   %true: caller should invoke svc_exit_thread()
 *   %false: caller should do nothing
 */
static inline bool svc_thread_should_stop(struct svc_rqst *rqstp)
{
        if (test_and_clear_bit(SP_NEED_VICTIM, &rqstp->rq_pool->sp_flags))
                set_bit(RQ_VICTIM, &rqstp->rq_flags);

        return test_bit(RQ_VICTIM, &rqstp->rq_flags);
}

/**
 * svc_thread_init_status - report whether thread has initialised successfully
 * @rqstp: the thread in question
 * @err: errno code
 *
 * After performing any initialisation that could fail, and before starting
 * normal work, each sunrpc svc_thread must call svc_thread_init_status()
 * with an appropriate error, or zero.
 *
 * If zero is passed, the thread is ready and must continue until
 * svc_thread_should_stop() returns true.  If a non-zero error is passed
 * the call will not return - the thread will exit.
 */
static inline void svc_thread_init_status(struct svc_rqst *rqstp, int err)
{
        store_release_wake_up(&rqstp->rq_err, err);
        if (err)
                kthread_exit(1);
}

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;
        struct sockaddr_storage daddr;  /* where reply must come from */
        size_t                  daddrlen;
        void                    *xprt_ctxt;
        struct cache_deferred_req handle;
        int                     argslen;
        __be32                  args[];
};

struct svc_process_info {
        union {
                int  (*dispatch)(struct svc_rqst *rqstp);
                struct {
                        unsigned int lovers;
                        unsigned int hivers;
                } mismatch;
        };
};

/*
 * RPC program - an array of these can use the same transport endpoint
 */
struct svc_program {
        u32                     pg_prog;        /* program number */
        unsigned int            pg_lovers;      /* lowest version */
        unsigned int            pg_hivers;      /* highest version */
        unsigned int            pg_nvers;       /* number of versions */
        const struct svc_version **pg_vers;     /* version array */
        char *                  pg_name;        /* service name */
        char *                  pg_class;       /* class name: services sharing authentication */
        enum svc_auth_status    (*pg_authenticate)(struct svc_rqst *rqstp);
        __be32                  (*pg_init_request)(struct svc_rqst *,
                                                   const struct svc_program *,
                                                   struct svc_process_info *);
        int                     (*pg_rpcbind_set)(struct net *net,
                                                  const struct svc_program *,
                                                  u32 version, int family,
                                                  unsigned short proto,
                                                  unsigned short port);
};

/*
 * RPC program version
 */
struct svc_version {
        u32                     vs_vers;        /* version number */
        u32                     vs_nproc;       /* number of procedures */
        const struct svc_procedure *vs_proc;    /* per-procedure info */
        unsigned long __percpu  *vs_count;      /* call counts */
        u32                     vs_xdrsize;     /* xdrsize needed for this version */

        /* Don't register with rpcbind */
        bool                    vs_hidden;

        /* Don't care if the rpcbind registration fails */
        bool                    vs_rpcb_optnl;

        /* Need xprt with congestion control */
        bool                    vs_need_cong_ctrl;

        /* Dispatch function */
        int                     (*vs_dispatch)(struct svc_rqst *rqstp);
};

/*
 * RPC procedure info
 */
struct svc_procedure {
        /* process the request: */
        __be32                  (*pc_func)(struct svc_rqst *);
        /* XDR decode args: */
        bool                    (*pc_decode)(struct svc_rqst *rqstp,
                                             struct xdr_stream *xdr);
        /* XDR encode result: */
        bool                    (*pc_encode)(struct svc_rqst *rqstp,
                                             struct xdr_stream *xdr);
        /* XDR free result: */
        void                    (*pc_release)(struct svc_rqst *);
        unsigned int            pc_argsize;     /* argument struct size */
        unsigned int            pc_argzero;     /* how much of argument to clear */
        unsigned int            pc_ressize;     /* result struct size */
        unsigned int            pc_cachetype;   /* cache info (NFS) */
        unsigned int            pc_xdrressize;  /* maximum size of XDR reply */
        const char *            pc_name;        /* for display */
};

/*
 * Function prototypes.
 */
int sunrpc_set_pool_mode(const char *val);
int sunrpc_get_pool_mode(char *val, size_t size);
void svc_rpcb_cleanup(struct svc_serv *serv, struct net *net);
int svc_bind(struct svc_serv *serv, struct net *net);
struct svc_serv *svc_create(struct svc_program *, unsigned int,
                            int (*threadfn)(void *data));
bool               svc_rqst_replace_page(struct svc_rqst *rqstp,
                                         struct page *page);
void               svc_rqst_release_pages(struct svc_rqst *rqstp);
int                svc_new_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 *prog,
                                     unsigned int nprog,
                                     struct svc_stat *stats,
                                     unsigned int bufsize,
                                     int (*threadfn)(void *data));
int                svc_set_pool_threads(struct svc_serv *serv, struct svc_pool *pool,
                                        unsigned int min_threads, unsigned int max_threads);
int                svc_set_num_threads(struct svc_serv *serv, unsigned int min_threads,
                                       unsigned int nrservs);
int                svc_pool_stats_open(struct svc_info *si, struct file *file);
void               svc_process(struct svc_rqst *rqstp);
void               svc_process_bc(struct rpc_rqst *req, struct svc_rqst *rqstp);
int                svc_register(const struct svc_serv *, struct net *, const int,
                                const unsigned short, const unsigned short);

void               svc_wake_up(struct svc_serv *);
void               svc_reserve(struct svc_rqst *rqstp, int space);
void               svc_pool_wake_idle_thread(struct svc_pool *pool);
struct svc_pool   *svc_pool_for_cpu(struct svc_serv *serv);
char *             svc_print_addr(struct svc_rqst *, char *, size_t);
const char *       svc_proc_name(const struct svc_rqst *rqstp);
int                svc_encode_result_payload(struct svc_rqst *rqstp,
                                             unsigned int offset,
                                             unsigned int length);
char              *svc_fill_symlink_pathname(struct svc_rqst *rqstp,
                                             struct kvec *first, void *p,
                                             size_t total);
__be32             svc_generic_init_request(struct svc_rqst *rqstp,
                                            const struct svc_program *progp,
                                            struct svc_process_info *procinfo);
int                svc_generic_rpcbind_set(struct net *net,
                                           const struct svc_program *progp,
                                           u32 version, int family,
                                           unsigned short proto,
                                           unsigned short port);

#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)
{
        svc_reserve(rqstp, space + rqstp->rq_auth_slack);
}

/**
 * svcxdr_init_decode - Prepare an xdr_stream for Call decoding
 * @rqstp: controlling server RPC transaction context
 *
 */
static inline void svcxdr_init_decode(struct svc_rqst *rqstp)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        struct xdr_buf *buf = &rqstp->rq_arg;
        struct kvec *argv = buf->head;

        WARN_ON(buf->len != buf->head->iov_len + buf->page_len + buf->tail->iov_len);
        buf->len = buf->head->iov_len + buf->page_len + buf->tail->iov_len;

        xdr_init_decode(xdr, buf, argv->iov_base, NULL);
        xdr_set_scratch_folio(xdr, rqstp->rq_scratch_folio);
}

/**
 * svcxdr_init_encode - Prepare an xdr_stream for svc Reply encoding
 * @rqstp: controlling server RPC transaction context
 *
 */
static inline void svcxdr_init_encode(struct svc_rqst *rqstp)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct xdr_buf *buf = &rqstp->rq_res;
        struct kvec *resv = buf->head;

        xdr_reset_scratch_buffer(xdr);

        xdr->buf = buf;
        xdr->iov = resv;
        xdr->p   = resv->iov_base + resv->iov_len;
        xdr->end = resv->iov_base + PAGE_SIZE;
        buf->len = resv->iov_len;
        xdr->page_ptr = buf->pages - 1;
        buf->buflen = PAGE_SIZE * (rqstp->rq_page_end - buf->pages);
        xdr->rqst = NULL;
}

/**
 * svcxdr_encode_opaque_pages - Insert pages into an xdr_stream
 * @xdr: xdr_stream to be updated
 * @pages: array of pages to insert
 * @base: starting offset of first data byte in @pages
 * @len: number of data bytes in @pages to insert
 *
 * After the @pages are added, the tail iovec is instantiated pointing
 * to end of the head buffer, and the stream is set up to encode
 * subsequent items into the tail.
 */
static inline void svcxdr_encode_opaque_pages(struct svc_rqst *rqstp,
                                              struct xdr_stream *xdr,
                                              struct page **pages,
                                              unsigned int base,
                                              unsigned int len)
{
        xdr_write_pages(xdr, pages, base, len);
        xdr->page_ptr = rqstp->rq_next_page - 1;
}

/**
 * svcxdr_set_auth_slack -
 * @rqstp: RPC transaction
 * @slack: buffer space to reserve for the transaction's security flavor
 *
 * Set the request's slack space requirement, and set aside that much
 * space in the rqstp's rq_res.head for use when the auth wraps the Reply.
 */
static inline void svcxdr_set_auth_slack(struct svc_rqst *rqstp, int slack)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct xdr_buf *buf = &rqstp->rq_res;
        struct kvec *resv = buf->head;

        rqstp->rq_auth_slack = slack;

        xdr->end -= XDR_QUADLEN(slack);
        buf->buflen -= rqstp->rq_auth_slack;

        WARN_ON(xdr->iov != resv);
        WARN_ON(xdr->p > xdr->end);
}

/**
 * svcxdr_set_accept_stat - Reserve space for the accept_stat field
 * @rqstp: RPC transaction context
 *
 * Return values:
 *   %true: Success
 *   %false: No response buffer space was available
 */
static inline bool svcxdr_set_accept_stat(struct svc_rqst *rqstp)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;

        rqstp->rq_accept_statp = xdr_reserve_space(xdr, XDR_UNIT);
        if (unlikely(!rqstp->rq_accept_statp))
                return false;
        *rqstp->rq_accept_statp = rpc_success;
        return true;
}

#endif /* SUNRPC_SVC_H */