1  /* SPDX-License-Identifier: GPL-2.0 */
2  /*
3   * linux/include/linux/sunrpc/svc.h
4   *
5   * RPC server declarations.
6   *
7   * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
8   */
9  
10  
11  #ifndef SUNRPC_SVC_H
12  #define SUNRPC_SVC_H
13  
14  #include <linux/in.h>
15  #include <linux/in6.h>
16  #include <linux/sunrpc/types.h>
17  #include <linux/sunrpc/xdr.h>
18  #include <linux/sunrpc/auth.h>
19  #include <linux/sunrpc/svcauth.h>
20  #include <linux/lwq.h>
21  #include <linux/wait.h>
22  #include <linux/mm.h>
23  #include <linux/pagevec.h>
24  #include <linux/kthread.h>
25  
26  /*
27   *
28   * RPC service thread pool.
29   *
30   * Pool of threads and temporary sockets.  Generally there is only
31   * a single one of these per RPC service, but on NUMA machines those
32   * services that can benefit from it (i.e. nfs but not lockd) will
33   * have one pool per NUMA node.  This optimisation reduces cross-
34   * node traffic on multi-node NUMA NFS servers.
35   */
36  struct svc_pool {
37  	unsigned int		sp_id;		/* pool id; also node id on NUMA */
38  	struct lwq		sp_xprts;	/* pending transports */
39  	unsigned int		sp_nrthreads;	/* # of threads in pool */
40  	struct list_head	sp_all_threads;	/* all server threads */
41  	struct llist_head	sp_idle_threads; /* idle server threads */
42  
43  	/* statistics on pool operation */
44  	struct percpu_counter	sp_messages_arrived;
45  	struct percpu_counter	sp_sockets_queued;
46  	struct percpu_counter	sp_threads_woken;
47  
48  	unsigned long		sp_flags;
49  } ____cacheline_aligned_in_smp;
50  
51  /* bits for sp_flags */
52  enum {
53  	SP_TASK_PENDING,	/* still work to do even if no xprt is queued */
54  	SP_NEED_VICTIM,		/* One thread needs to agree to exit */
55  	SP_VICTIM_REMAINS,	/* One thread needs to actually exit */
56  };
57  
58  
59  /*
60   * RPC service.
61   *
62   * An RPC service is a ``daemon,'' possibly multithreaded, which
63   * receives and processes incoming RPC messages.
64   * It has one or more transport sockets associated with it, and maintains
65   * a list of idle threads waiting for input.
66   *
67   * We currently do not support more than one RPC program per daemon.
68   */
69  struct svc_serv {
70  	struct svc_program *	sv_programs;	/* RPC programs */
71  	struct svc_stat *	sv_stats;	/* RPC statistics */
72  	spinlock_t		sv_lock;
73  	unsigned int		sv_nprogs;	/* Number of sv_programs */
74  	unsigned int		sv_nrthreads;	/* # of server threads */
75  	unsigned int		sv_maxconn;	/* max connections allowed or
76  						 * '0' causing max to be based
77  						 * on number of threads. */
78  
79  	unsigned int		sv_max_payload;	/* datagram payload size */
80  	unsigned int		sv_max_mesg;	/* max_payload + 1 page for overheads */
81  	unsigned int		sv_xdrsize;	/* XDR buffer size */
82  	struct list_head	sv_permsocks;	/* all permanent sockets */
83  	struct list_head	sv_tempsocks;	/* all temporary sockets */
84  	int			sv_tmpcnt;	/* count of temporary sockets */
85  	struct timer_list	sv_temptimer;	/* timer for aging temporary sockets */
86  
87  	char *			sv_name;	/* service name */
88  
89  	unsigned int		sv_nrpools;	/* number of thread pools */
90  	bool			sv_is_pooled;	/* is this a pooled service? */
91  	struct svc_pool *	sv_pools;	/* array of thread pools */
92  	int			(*sv_threadfn)(void *data);
93  
94  #if defined(CONFIG_SUNRPC_BACKCHANNEL)
95  	struct lwq		sv_cb_list;	/* queue for callback requests
96  						 * that arrive over the same
97  						 * connection */
98  	bool			sv_bc_enabled;	/* service uses backchannel */
99  #endif /* CONFIG_SUNRPC_BACKCHANNEL */
100  };
101  
102  /* This is used by pool_stats to find and lock an svc */
103  struct svc_info {
104  	struct svc_serv		*serv;
105  	struct mutex		*mutex;
106  };
107  
108  void svc_destroy(struct svc_serv **svcp);
109  
110  /*
111   * Maximum payload size supported by a kernel RPC server.
112   * This is use to determine the max number of pages nfsd is
113   * willing to return in a single READ operation.
114   *
115   * These happen to all be powers of 2, which is not strictly
116   * necessary but helps enforce the real limitation, which is
117   * that they should be multiples of PAGE_SIZE.
118   *
119   * For UDP transports, a block plus NFS,RPC, and UDP headers
120   * has to fit into the IP datagram limit of 64K.  The largest
121   * feasible number for all known page sizes is probably 48K,
122   * but we choose 32K here.  This is the same as the historical
123   * Linux limit; someone who cares more about NFS/UDP performance
124   * can test a larger number.
125   *
126   * For TCP transports we have more freedom.  A size of 1MB is
127   * chosen to match the client limit.  Other OSes are known to
128   * have larger limits, but those numbers are probably beyond
129   * the point of diminishing returns.
130   */
131  #define RPCSVC_MAXPAYLOAD	(1*1024*1024u)
132  #define RPCSVC_MAXPAYLOAD_TCP	RPCSVC_MAXPAYLOAD
133  #define RPCSVC_MAXPAYLOAD_UDP	(32*1024u)
134  
135  extern u32 svc_max_payload(const struct svc_rqst *rqstp);
136  
137  /*
138   * RPC Requests and replies are stored in one or more pages.
139   * We maintain an array of pages for each server thread.
140   * Requests are copied into these pages as they arrive.  Remaining
141   * pages are available to write the reply into.
142   *
143   * Pages are sent using ->sendmsg with MSG_SPLICE_PAGES so each server thread
144   * needs to allocate more to replace those used in sending.  To help keep track
145   * of these pages we have a receive list where all pages initialy live, and a
146   * send list where pages are moved to when there are to be part of a reply.
147   *
148   * We use xdr_buf for holding responses as it fits well with NFS
149   * read responses (that have a header, and some data pages, and possibly
150   * a tail) and means we can share some client side routines.
151   *
152   * The xdr_buf.head kvec always points to the first page in the rq_*pages
153   * list.  The xdr_buf.pages pointer points to the second page on that
154   * list.  xdr_buf.tail points to the end of the first page.
155   * This assumes that the non-page part of an rpc reply will fit
156   * in a page - NFSd ensures this.  lockd also has no trouble.
157   *
158   * Each request/reply pair can have at most one "payload", plus two pages,
159   * one for the request, and one for the reply.
160   * We using ->sendfile to return read data, we might need one extra page
161   * if the request is not page-aligned.  So add another '1'.
162   */
163  #define RPCSVC_MAXPAGES		((RPCSVC_MAXPAYLOAD+PAGE_SIZE-1)/PAGE_SIZE \
164  				+ 2 + 1)
165  
166  /*
167   * The context of a single thread, including the request currently being
168   * processed.
169   */
170  struct svc_rqst {
171  	struct list_head	rq_all;		/* all threads list */
172  	struct llist_node	rq_idle;	/* On the idle list */
173  	struct rcu_head		rq_rcu_head;	/* for RCU deferred kfree */
174  	struct svc_xprt *	rq_xprt;	/* transport ptr */
175  
176  	struct sockaddr_storage	rq_addr;	/* peer address */
177  	size_t			rq_addrlen;
178  	struct sockaddr_storage	rq_daddr;	/* dest addr of request
179  						 *  - reply from here */
180  	size_t			rq_daddrlen;
181  
182  	struct svc_serv *	rq_server;	/* RPC service definition */
183  	struct svc_pool *	rq_pool;	/* thread pool */
184  	const struct svc_procedure *rq_procinfo;/* procedure info */
185  	struct auth_ops *	rq_authop;	/* authentication flavour */
186  	struct svc_cred		rq_cred;	/* auth info */
187  	void *			rq_xprt_ctxt;	/* transport specific context ptr */
188  	struct svc_deferred_req*rq_deferred;	/* deferred request we are replaying */
189  
190  	struct xdr_buf		rq_arg;
191  	struct xdr_stream	rq_arg_stream;
192  	struct xdr_stream	rq_res_stream;
193  	struct page		*rq_scratch_page;
194  	struct xdr_buf		rq_res;
195  	struct page		*rq_pages[RPCSVC_MAXPAGES + 1];
196  	struct page *		*rq_respages;	/* points into rq_pages */
197  	struct page *		*rq_next_page; /* next reply page to use */
198  	struct page *		*rq_page_end;  /* one past the last page */
199  
200  	struct folio_batch	rq_fbatch;
201  	struct kvec		rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
202  	struct bio_vec		rq_bvec[RPCSVC_MAXPAGES];
203  
204  	__be32			rq_xid;		/* transmission id */
205  	u32			rq_prog;	/* program number */
206  	u32			rq_vers;	/* program version */
207  	u32			rq_proc;	/* procedure number */
208  	u32			rq_prot;	/* IP protocol */
209  	int			rq_cachetype;	/* catering to nfsd */
210  	unsigned long		rq_flags;	/* flags field */
211  	ktime_t			rq_qtime;	/* enqueue time */
212  
213  	void *			rq_argp;	/* decoded arguments */
214  	void *			rq_resp;	/* xdr'd results */
215  	__be32			*rq_accept_statp;
216  	void *			rq_auth_data;	/* flavor-specific data */
217  	__be32			rq_auth_stat;	/* authentication status */
218  	int			rq_auth_slack;	/* extra space xdr code
219  						 * should leave in head
220  						 * for krb5i, krb5p.
221  						 */
222  	int			rq_reserved;	/* space on socket outq
223  						 * reserved for this request
224  						 */
225  	ktime_t			rq_stime;	/* start time */
226  
227  	struct cache_req	rq_chandle;	/* handle passed to caches for
228  						 * request delaying
229  						 */
230  	/* Catering to nfsd */
231  	struct auth_domain *	rq_client;	/* RPC peer info */
232  	struct auth_domain *	rq_gssclient;	/* "gss/"-style peer info */
233  	struct task_struct	*rq_task;	/* service thread */
234  	struct net		*rq_bc_net;	/* pointer to backchannel's
235  						 * net namespace
236  						 */
237  
238  	int			rq_err;		/* Thread sets this to inidicate
239  						 * initialisation success.
240  						 */
241  
242  	unsigned long	bc_to_initval;
243  	unsigned int	bc_to_retries;
244  	void **			rq_lease_breaker; /* The v4 client breaking a lease */
245  	unsigned int		rq_status_counter; /* RPC processing counter */
246  };
247  
248  /* bits for rq_flags */
249  enum {
250  	RQ_SECURE,		/* secure port */
251  	RQ_LOCAL,		/* local request */
252  	RQ_USEDEFERRAL,		/* use deferral */
253  	RQ_DROPME,		/* drop current reply */
254  	RQ_VICTIM,		/* Have agreed to shut down */
255  	RQ_DATA,		/* request has data */
256  };
257  
258  #define SVC_NET(rqst) (rqst->rq_xprt ? rqst->rq_xprt->xpt_net : rqst->rq_bc_net)
259  
260  /*
261   * Rigorous type checking on sockaddr type conversions
262   */
svc_addr_in(const struct svc_rqst * rqst)263  static inline struct sockaddr_in *svc_addr_in(const struct svc_rqst *rqst)
264  {
265  	return (struct sockaddr_in *) &rqst->rq_addr;
266  }
267  
svc_addr_in6(const struct svc_rqst * rqst)268  static inline struct sockaddr_in6 *svc_addr_in6(const struct svc_rqst *rqst)
269  {
270  	return (struct sockaddr_in6 *) &rqst->rq_addr;
271  }
272  
svc_addr(const struct svc_rqst * rqst)273  static inline struct sockaddr *svc_addr(const struct svc_rqst *rqst)
274  {
275  	return (struct sockaddr *) &rqst->rq_addr;
276  }
277  
svc_daddr_in(const struct svc_rqst * rqst)278  static inline struct sockaddr_in *svc_daddr_in(const struct svc_rqst *rqst)
279  {
280  	return (struct sockaddr_in *) &rqst->rq_daddr;
281  }
282  
svc_daddr_in6(const struct svc_rqst * rqst)283  static inline struct sockaddr_in6 *svc_daddr_in6(const struct svc_rqst *rqst)
284  {
285  	return (struct sockaddr_in6 *) &rqst->rq_daddr;
286  }
287  
svc_daddr(const struct svc_rqst * rqst)288  static inline struct sockaddr *svc_daddr(const struct svc_rqst *rqst)
289  {
290  	return (struct sockaddr *) &rqst->rq_daddr;
291  }
292  
293  /**
294   * svc_thread_should_stop - check if this thread should stop
295   * @rqstp: the thread that might need to stop
296   *
297   * To stop an svc thread, the pool flags SP_NEED_VICTIM and SP_VICTIM_REMAINS
298   * are set.  The first thread which sees SP_NEED_VICTIM clears it, becoming
299   * the victim using this function.  It should then promptly call
300   * svc_exit_thread() to complete the process, clearing SP_VICTIM_REMAINS
301   * so the task waiting for a thread to exit can wake and continue.
302   *
303   * Return values:
304   *   %true: caller should invoke svc_exit_thread()
305   *   %false: caller should do nothing
306   */
svc_thread_should_stop(struct svc_rqst * rqstp)307  static inline bool svc_thread_should_stop(struct svc_rqst *rqstp)
308  {
309  	if (test_and_clear_bit(SP_NEED_VICTIM, &rqstp->rq_pool->sp_flags))
310  		set_bit(RQ_VICTIM, &rqstp->rq_flags);
311  
312  	return test_bit(RQ_VICTIM, &rqstp->rq_flags);
313  }
314  
315  /**
316   * svc_thread_init_status - report whether thread has initialised successfully
317   * @rqstp: the thread in question
318   * @err: errno code
319   *
320   * After performing any initialisation that could fail, and before starting
321   * normal work, each sunrpc svc_thread must call svc_thread_init_status()
322   * with an appropriate error, or zero.
323   *
324   * If zero is passed, the thread is ready and must continue until
325   * svc_thread_should_stop() returns true.  If a non-zero error is passed
326   * the call will not return - the thread will exit.
327   */
svc_thread_init_status(struct svc_rqst * rqstp,int err)328  static inline void svc_thread_init_status(struct svc_rqst *rqstp, int err)
329  {
330  	rqstp->rq_err = err;
331  	/* memory barrier ensures assignment to error above is visible before
332  	 * waitqueue_active() test below completes.
333  	 */
334  	smp_mb();
335  	wake_up_var(&rqstp->rq_err);
336  	if (err)
337  		kthread_exit(1);
338  }
339  
340  struct svc_deferred_req {
341  	u32			prot;	/* protocol (UDP or TCP) */
342  	struct svc_xprt		*xprt;
343  	struct sockaddr_storage	addr;	/* where reply must go */
344  	size_t			addrlen;
345  	struct sockaddr_storage	daddr;	/* where reply must come from */
346  	size_t			daddrlen;
347  	void			*xprt_ctxt;
348  	struct cache_deferred_req handle;
349  	int			argslen;
350  	__be32			args[];
351  };
352  
353  struct svc_process_info {
354  	union {
355  		int  (*dispatch)(struct svc_rqst *rqstp);
356  		struct {
357  			unsigned int lovers;
358  			unsigned int hivers;
359  		} mismatch;
360  	};
361  };
362  
363  /*
364   * RPC program - an array of these can use the same transport endpoint
365   */
366  struct svc_program {
367  	u32			pg_prog;	/* program number */
368  	unsigned int		pg_lovers;	/* lowest version */
369  	unsigned int		pg_hivers;	/* highest version */
370  	unsigned int		pg_nvers;	/* number of versions */
371  	const struct svc_version **pg_vers;	/* version array */
372  	char *			pg_name;	/* service name */
373  	char *			pg_class;	/* class name: services sharing authentication */
374  	enum svc_auth_status	(*pg_authenticate)(struct svc_rqst *rqstp);
375  	__be32			(*pg_init_request)(struct svc_rqst *,
376  						   const struct svc_program *,
377  						   struct svc_process_info *);
378  	int			(*pg_rpcbind_set)(struct net *net,
379  						  const struct svc_program *,
380  						  u32 version, int family,
381  						  unsigned short proto,
382  						  unsigned short port);
383  };
384  
385  /*
386   * RPC program version
387   */
388  struct svc_version {
389  	u32			vs_vers;	/* version number */
390  	u32			vs_nproc;	/* number of procedures */
391  	const struct svc_procedure *vs_proc;	/* per-procedure info */
392  	unsigned long __percpu	*vs_count;	/* call counts */
393  	u32			vs_xdrsize;	/* xdrsize needed for this version */
394  
395  	/* Don't register with rpcbind */
396  	bool			vs_hidden;
397  
398  	/* Don't care if the rpcbind registration fails */
399  	bool			vs_rpcb_optnl;
400  
401  	/* Need xprt with congestion control */
402  	bool			vs_need_cong_ctrl;
403  
404  	/* Dispatch function */
405  	int			(*vs_dispatch)(struct svc_rqst *rqstp);
406  };
407  
408  /*
409   * RPC procedure info
410   */
411  struct svc_procedure {
412  	/* process the request: */
413  	__be32			(*pc_func)(struct svc_rqst *);
414  	/* XDR decode args: */
415  	bool			(*pc_decode)(struct svc_rqst *rqstp,
416  					     struct xdr_stream *xdr);
417  	/* XDR encode result: */
418  	bool			(*pc_encode)(struct svc_rqst *rqstp,
419  					     struct xdr_stream *xdr);
420  	/* XDR free result: */
421  	void			(*pc_release)(struct svc_rqst *);
422  	unsigned int		pc_argsize;	/* argument struct size */
423  	unsigned int		pc_argzero;	/* how much of argument to clear */
424  	unsigned int		pc_ressize;	/* result struct size */
425  	unsigned int		pc_cachetype;	/* cache info (NFS) */
426  	unsigned int		pc_xdrressize;	/* maximum size of XDR reply */
427  	const char *		pc_name;	/* for display */
428  };
429  
430  /*
431   * Function prototypes.
432   */
433  int sunrpc_set_pool_mode(const char *val);
434  int sunrpc_get_pool_mode(char *val, size_t size);
435  void svc_rpcb_cleanup(struct svc_serv *serv, struct net *net);
436  int svc_bind(struct svc_serv *serv, struct net *net);
437  struct svc_serv *svc_create(struct svc_program *, unsigned int,
438  			    int (*threadfn)(void *data));
439  bool		   svc_rqst_replace_page(struct svc_rqst *rqstp,
440  					 struct page *page);
441  void		   svc_rqst_release_pages(struct svc_rqst *rqstp);
442  void		   svc_exit_thread(struct svc_rqst *);
443  struct svc_serv *  svc_create_pooled(struct svc_program *prog,
444  				     unsigned int nprog,
445  				     struct svc_stat *stats,
446  				     unsigned int bufsize,
447  				     int (*threadfn)(void *data));
448  int		   svc_set_num_threads(struct svc_serv *, struct svc_pool *, int);
449  int		   svc_pool_stats_open(struct svc_info *si, struct file *file);
450  void		   svc_process(struct svc_rqst *rqstp);
451  void		   svc_process_bc(struct rpc_rqst *req, struct svc_rqst *rqstp);
452  int		   svc_register(const struct svc_serv *, struct net *, const int,
453  				const unsigned short, const unsigned short);
454  
455  void		   svc_wake_up(struct svc_serv *);
456  void		   svc_reserve(struct svc_rqst *rqstp, int space);
457  void		   svc_pool_wake_idle_thread(struct svc_pool *pool);
458  struct svc_pool   *svc_pool_for_cpu(struct svc_serv *serv);
459  char *		   svc_print_addr(struct svc_rqst *, char *, size_t);
460  const char *	   svc_proc_name(const struct svc_rqst *rqstp);
461  int		   svc_encode_result_payload(struct svc_rqst *rqstp,
462  					     unsigned int offset,
463  					     unsigned int length);
464  unsigned int	   svc_fill_write_vector(struct svc_rqst *rqstp,
465  					 struct xdr_buf *payload);
466  char		  *svc_fill_symlink_pathname(struct svc_rqst *rqstp,
467  					     struct kvec *first, void *p,
468  					     size_t total);
469  __be32		   svc_generic_init_request(struct svc_rqst *rqstp,
470  					    const struct svc_program *progp,
471  					    struct svc_process_info *procinfo);
472  int		   svc_generic_rpcbind_set(struct net *net,
473  					   const struct svc_program *progp,
474  					   u32 version, int family,
475  					   unsigned short proto,
476  					   unsigned short port);
477  
478  #define	RPC_MAX_ADDRBUFLEN	(63U)
479  
480  /*
481   * When we want to reduce the size of the reserved space in the response
482   * buffer, we need to take into account the size of any checksum data that
483   * may be at the end of the packet. This is difficult to determine exactly
484   * for all cases without actually generating the checksum, so we just use a
485   * static value.
486   */
svc_reserve_auth(struct svc_rqst * rqstp,int space)487  static inline void svc_reserve_auth(struct svc_rqst *rqstp, int space)
488  {
489  	svc_reserve(rqstp, space + rqstp->rq_auth_slack);
490  }
491  
492  /**
493   * svcxdr_init_decode - Prepare an xdr_stream for Call decoding
494   * @rqstp: controlling server RPC transaction context
495   *
496   */
svcxdr_init_decode(struct svc_rqst * rqstp)497  static inline void svcxdr_init_decode(struct svc_rqst *rqstp)
498  {
499  	struct xdr_stream *xdr = &rqstp->rq_arg_stream;
500  	struct xdr_buf *buf = &rqstp->rq_arg;
501  	struct kvec *argv = buf->head;
502  
503  	WARN_ON(buf->len != buf->head->iov_len + buf->page_len + buf->tail->iov_len);
504  	buf->len = buf->head->iov_len + buf->page_len + buf->tail->iov_len;
505  
506  	xdr_init_decode(xdr, buf, argv->iov_base, NULL);
507  	xdr_set_scratch_page(xdr, rqstp->rq_scratch_page);
508  }
509  
510  /**
511   * svcxdr_init_encode - Prepare an xdr_stream for svc Reply encoding
512   * @rqstp: controlling server RPC transaction context
513   *
514   */
svcxdr_init_encode(struct svc_rqst * rqstp)515  static inline void svcxdr_init_encode(struct svc_rqst *rqstp)
516  {
517  	struct xdr_stream *xdr = &rqstp->rq_res_stream;
518  	struct xdr_buf *buf = &rqstp->rq_res;
519  	struct kvec *resv = buf->head;
520  
521  	xdr_reset_scratch_buffer(xdr);
522  
523  	xdr->buf = buf;
524  	xdr->iov = resv;
525  	xdr->p   = resv->iov_base + resv->iov_len;
526  	xdr->end = resv->iov_base + PAGE_SIZE;
527  	buf->len = resv->iov_len;
528  	xdr->page_ptr = buf->pages - 1;
529  	buf->buflen = PAGE_SIZE * (rqstp->rq_page_end - buf->pages);
530  	xdr->rqst = NULL;
531  }
532  
533  /**
534   * svcxdr_encode_opaque_pages - Insert pages into an xdr_stream
535   * @xdr: xdr_stream to be updated
536   * @pages: array of pages to insert
537   * @base: starting offset of first data byte in @pages
538   * @len: number of data bytes in @pages to insert
539   *
540   * After the @pages are added, the tail iovec is instantiated pointing
541   * to end of the head buffer, and the stream is set up to encode
542   * subsequent items into the tail.
543   */
svcxdr_encode_opaque_pages(struct svc_rqst * rqstp,struct xdr_stream * xdr,struct page ** pages,unsigned int base,unsigned int len)544  static inline void svcxdr_encode_opaque_pages(struct svc_rqst *rqstp,
545  					      struct xdr_stream *xdr,
546  					      struct page **pages,
547  					      unsigned int base,
548  					      unsigned int len)
549  {
550  	xdr_write_pages(xdr, pages, base, len);
551  	xdr->page_ptr = rqstp->rq_next_page - 1;
552  }
553  
554  /**
555   * svcxdr_set_auth_slack -
556   * @rqstp: RPC transaction
557   * @slack: buffer space to reserve for the transaction's security flavor
558   *
559   * Set the request's slack space requirement, and set aside that much
560   * space in the rqstp's rq_res.head for use when the auth wraps the Reply.
561   */
svcxdr_set_auth_slack(struct svc_rqst * rqstp,int slack)562  static inline void svcxdr_set_auth_slack(struct svc_rqst *rqstp, int slack)
563  {
564  	struct xdr_stream *xdr = &rqstp->rq_res_stream;
565  	struct xdr_buf *buf = &rqstp->rq_res;
566  	struct kvec *resv = buf->head;
567  
568  	rqstp->rq_auth_slack = slack;
569  
570  	xdr->end -= XDR_QUADLEN(slack);
571  	buf->buflen -= rqstp->rq_auth_slack;
572  
573  	WARN_ON(xdr->iov != resv);
574  	WARN_ON(xdr->p > xdr->end);
575  }
576  
577  /**
578   * svcxdr_set_accept_stat - Reserve space for the accept_stat field
579   * @rqstp: RPC transaction context
580   *
581   * Return values:
582   *   %true: Success
583   *   %false: No response buffer space was available
584   */
svcxdr_set_accept_stat(struct svc_rqst * rqstp)585  static inline bool svcxdr_set_accept_stat(struct svc_rqst *rqstp)
586  {
587  	struct xdr_stream *xdr = &rqstp->rq_res_stream;
588  
589  	rqstp->rq_accept_statp = xdr_reserve_space(xdr, XDR_UNIT);
590  	if (unlikely(!rqstp->rq_accept_statp))
591  		return false;
592  	*rqstp->rq_accept_statp = rpc_success;
593  	return true;
594  }
595  
596  #endif /* SUNRPC_SVC_H */
597