xref: /linux-6.12.1/include/linux/sunrpc/svc.h

/* 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 */
	struct lwq		sp_xprts;	/* pending transports */
	unsigned int		sp_nrthreads;	/* # of threads in pool */
	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 */
};


/*
 * 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 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 */
	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 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 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.
 *
 * 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)

/*
 * 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 page		*rq_scratch_page;
	struct xdr_buf		rq_res;
	struct page		*rq_pages[RPCSVC_MAXPAGES + 1];
	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 kvec		rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
	struct bio_vec		rq_bvec[RPCSVC_MAXPAGES];

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

/* 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)
{
	rqstp->rq_err = err;
	/* memory barrier ensures assignment to error above is visible before
	 * waitqueue_active() test below completes.
	 */
	smp_mb();
	wake_up_var(&rqstp->rq_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);
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_num_threads(struct svc_serv *, struct svc_pool *, int);
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);
unsigned int	   svc_fill_write_vector(struct svc_rqst *rqstp,
					 struct xdr_buf *payload);
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_page(xdr, rqstp->rq_scratch_page);
}

/**
 * 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 */