path: root/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/folio_batch.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 Call and Reply messages each have their own page array.
 * rq_pages holds the incoming Call message; rq_respages holds
 * the outgoing Reply message. Both arrays are sized to
 * svc_serv_maxpages() entries and are allocated dynamically.
 *
 * Pages are sent using ->sendmsg with MSG_SPLICE_PAGES so each
 * server thread needs to allocate more to replace those used in
 * sending.
 *
 * rq_pages request page contract:
 *
 * Transport receive paths that move request data pages out of
 * rq_pages -- TCP multi-fragment reassembly (svc_tcp_save_pages)
 * and RDMA Read I/O (svc_rdma_clear_rqst_pages) -- NULL those
 * entries to prevent svc_rqst_release_pages() from freeing pages
 * still in transport use, and set rq_pages_nfree to the count.
 * svc_alloc_arg() refills only that many rq_pages entries.
 *
 * For rq_respages, svc_rqst_release_pages() NULLs entries in
 * [rq_respages, rq_next_page) after each RPC. svc_alloc_arg()
 * refills only that range.
 *
 * xdr_buf holds responses; the structure fits NFS read responses
 * (header, data pages, optional tail) and enables sharing of
 * 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 page array can hold at most one payload plus two
 * overhead pages (one for the RPC header, one for tail data).
 * 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.
 *
 * RPC programs are free to use rq_private to stash thread-local information.
 * The sunrpc layer will not access it.
 */
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;	/* entries per page array */
	unsigned long		rq_pages_nfree;	/* rq_pages entries NULLed by transport */
	struct page *		*rq_pages;	/* Call buffer pages */
	struct page *		*rq_respages;	/* Reply buffer pages */
	struct page *		*rq_next_page; /* next reply page to use */
	struct page *		*rq_page_end;  /* one past the last reply 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 */
	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_private;	/* For use by the service thread */
};

/* 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