/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Request reply cache. This was heavily inspired by the
 * implementation in 4.3BSD/4.4BSD.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#ifndef NFSCACHE_H
#define NFSCACHE_H

#include <linux/sunrpc/svc.h>
#include "nfsd.h"

/*
 * Representation of a reply cache entry.
 *
 * Note that we use a sockaddr_in6 to hold the address instead of the more
 * typical sockaddr_storage. This is for space reasons, since sockaddr_storage
 * is much larger than a sockaddr_in6.
 */
struct nfsd_cacherep {
        struct {
                /* Keep often-read xid, csum in the same cache line: */
                __be32                  k_xid;
                __wsum                  k_csum;
                u32                     k_proc;
                u32                     k_prot;
                u32                     k_vers;
                unsigned int            k_len;
                struct sockaddr_in6     k_addr;
        } c_key;

        struct rb_node          c_node;
        struct list_head        c_lru;
        unsigned char           c_state,        /* unused, inprog, done */
                                c_type,         /* status, buffer */
                                c_secure : 1;   /* req came from port < 1024 */
        unsigned long           c_timestamp;
        union {
                struct kvec     u_vec;
                __be32          u_status;
        }                       c_u;
};

#define c_replvec               c_u.u_vec
#define c_replstat              c_u.u_status

/* cache entry states */
enum {
        RC_UNUSED,
        RC_INPROG,
        RC_DONE
};

/* return values */
enum {
        RC_DROPIT,
        RC_REPLY,
        RC_DOIT
};

/*
 * Cache types.
 * We may want to add more types one day, e.g. for diropres and
 * attrstat replies. Using cache entries with fixed length instead
 * of buffer pointers may be more efficient.
 */
enum {
        RC_NOCACHE,
        RC_REPLSTAT,
        RC_REPLBUFF,
};

/* Cache entries expire after this time period */
#define RC_EXPIRE               (120 * HZ)

/* Checksum this amount of the request */
#define RC_CSUMLEN              (256U)

int     nfsd_drc_slab_create(void);
void    nfsd_drc_slab_free(void);
int     nfsd_reply_cache_init(struct nfsd_net *);
void    nfsd_reply_cache_shutdown(struct nfsd_net *);
int     nfsd_cache_lookup(struct svc_rqst *rqstp, unsigned int start,
                          unsigned int len, struct nfsd_cacherep **cacherep);
void    nfsd_cache_update(struct svc_rqst *rqstp, struct nfsd_cacherep *rp,
                          int cachetype, __be32 *statp);
int     nfsd_reply_cache_stats_show(struct seq_file *m, void *v);

#endif /* NFSCACHE_H */