1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Request reply cache. This was heavily inspired by the
4  * implementation in 4.3BSD/4.4BSD.
5  *
6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
7  */
8 
9 #ifndef NFSCACHE_H
10 #define NFSCACHE_H
11 
12 #include <linux/sunrpc/svc.h>
13 
14 /*
15  * Representation of a reply cache entry.
16  *
17  * Note that we use a sockaddr_in6 to hold the address instead of the more
18  * typical sockaddr_storage. This is for space reasons, since sockaddr_storage
19  * is much larger than a sockaddr_in6.
20  */
21 struct svc_cacherep {
22 	struct list_head	c_lru;
23 
24 	unsigned char		c_state,	/* unused, inprog, done */
25 				c_type,		/* status, buffer */
26 				c_secure : 1;	/* req came from port < 1024 */
27 	struct sockaddr_in6	c_addr;
28 	__be32			c_xid;
29 	u32			c_prot;
30 	u32			c_proc;
31 	u32			c_vers;
32 	unsigned int		c_len;
33 	__wsum			c_csum;
34 	unsigned long		c_timestamp;
35 	union {
36 		struct kvec	u_vec;
37 		__be32		u_status;
38 	}			c_u;
39 };
40 
41 #define c_replvec		c_u.u_vec
42 #define c_replstat		c_u.u_status
43 
44 /* cache entry states */
45 enum {
46 	RC_UNUSED,
47 	RC_INPROG,
48 	RC_DONE
49 };
50 
51 /* return values */
52 enum {
53 	RC_DROPIT,
54 	RC_REPLY,
55 	RC_DOIT
56 };
57 
58 /*
59  * Cache types.
60  * We may want to add more types one day, e.g. for diropres and
61  * attrstat replies. Using cache entries with fixed length instead
62  * of buffer pointers may be more efficient.
63  */
64 enum {
65 	RC_NOCACHE,
66 	RC_REPLSTAT,
67 	RC_REPLBUFF,
68 };
69 
70 /* Cache entries expire after this time period */
71 #define RC_EXPIRE		(120 * HZ)
72 
73 /* Checksum this amount of the request */
74 #define RC_CSUMLEN		(256U)
75 
76 int	nfsd_reply_cache_init(void);
77 void	nfsd_reply_cache_shutdown(void);
78 int	nfsd_cache_lookup(struct svc_rqst *);
79 void	nfsd_cache_update(struct svc_rqst *, int, __be32 *);
80 int	nfsd_reply_cache_stats_open(struct inode *, struct file *);
81 
82 #endif /* NFSCACHE_H */
83