xref: /linux/fs/nfsd/cache.h (revision ab52c59103002b49f2455371e4b9c56ba3ef1781)
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 #include "netns.h"
14 
15 /*
16  * Representation of a reply cache entry.
17  *
18  * Note that we use a sockaddr_in6 to hold the address instead of the more
19  * typical sockaddr_storage. This is for space reasons, since sockaddr_storage
20  * is much larger than a sockaddr_in6.
21  */
22 struct nfsd_cacherep {
23 	struct {
24 		/* Keep often-read xid, csum in the same cache line: */
25 		__be32			k_xid;
26 		__wsum			k_csum;
27 		u32			k_proc;
28 		u32			k_prot;
29 		u32			k_vers;
30 		unsigned int		k_len;
31 		struct sockaddr_in6	k_addr;
32 	} c_key;
33 
34 	struct rb_node		c_node;
35 	struct list_head	c_lru;
36 	unsigned char		c_state,	/* unused, inprog, done */
37 				c_type,		/* status, buffer */
38 				c_secure : 1;	/* req came from port < 1024 */
39 	unsigned long		c_timestamp;
40 	union {
41 		struct kvec	u_vec;
42 		__be32		u_status;
43 	}			c_u;
44 };
45 
46 #define c_replvec		c_u.u_vec
47 #define c_replstat		c_u.u_status
48 
49 /* cache entry states */
50 enum {
51 	RC_UNUSED,
52 	RC_INPROG,
53 	RC_DONE
54 };
55 
56 /* return values */
57 enum {
58 	RC_DROPIT,
59 	RC_REPLY,
60 	RC_DOIT
61 };
62 
63 /*
64  * Cache types.
65  * We may want to add more types one day, e.g. for diropres and
66  * attrstat replies. Using cache entries with fixed length instead
67  * of buffer pointers may be more efficient.
68  */
69 enum {
70 	RC_NOCACHE,
71 	RC_REPLSTAT,
72 	RC_REPLBUFF,
73 };
74 
75 /* Cache entries expire after this time period */
76 #define RC_EXPIRE		(120 * HZ)
77 
78 /* Checksum this amount of the request */
79 #define RC_CSUMLEN		(256U)
80 
81 int	nfsd_drc_slab_create(void);
82 void	nfsd_drc_slab_free(void);
83 int	nfsd_reply_cache_init(struct nfsd_net *);
84 void	nfsd_reply_cache_shutdown(struct nfsd_net *);
85 int	nfsd_cache_lookup(struct svc_rqst *rqstp, unsigned int start,
86 			  unsigned int len, struct nfsd_cacherep **cacherep);
87 void	nfsd_cache_update(struct svc_rqst *rqstp, struct nfsd_cacherep *rp,
88 			  int cachetype, __be32 *statp);
89 int	nfsd_reply_cache_stats_show(struct seq_file *m, void *v);
90 
91 #endif /* NFSCACHE_H */
92