/* SPDX-License-Identifier: GPL-2.0 */
/*
 * fs/nfs/nfs4session.h
 *
 * Copyright (c) 2012 Trond Myklebust <Trond.Myklebust@netapp.com>
 *
 */
#ifndef __LINUX_FS_NFS_NFS4SESSION_H
#define __LINUX_FS_NFS_NFS4SESSION_H

/* maximum number of slots to use */
#define NFS4_DEF_SLOT_TABLE_SIZE (64U)
#define NFS4_DEF_CB_SLOT_TABLE_SIZE (16U)
#define NFS4_MAX_SLOT_TABLE (1024U)
#define NFS4_MAX_SLOTID (NFS4_MAX_SLOT_TABLE - 1U)
#define NFS4_NO_SLOT ((u32)-1)

#if IS_ENABLED(CONFIG_NFS_V4)

/* Sessions slot seqid */
struct nfs4_slot {
        struct nfs4_slot_table  *table;
        struct nfs4_slot        *next;
        unsigned long           generation;
        u32                     slot_nr;
        u32                     seq_nr;
        u32                     seq_nr_last_acked;
        u32                     seq_nr_highest_sent;
        unsigned int            privileged : 1,
                                seq_done : 1;
};

/* Sessions */
enum nfs4_slot_tbl_state {
        NFS4_SLOT_TBL_DRAINING,
};

#define SLOT_TABLE_SZ DIV_ROUND_UP(NFS4_MAX_SLOT_TABLE, BITS_PER_LONG)
struct nfs4_slot_table {
        struct nfs4_session *session;           /* Parent session */
        struct nfs4_slot *slots;                /* seqid per slot */
        unsigned long   used_slots[SLOT_TABLE_SZ]; /* used/unused bitmap */
        spinlock_t      slot_tbl_lock;
        struct rpc_wait_queue   slot_tbl_waitq; /* allocators may wait here */
        wait_queue_head_t       slot_waitq;     /* Completion wait on slot */
        u32             max_slots;              /* # slots in table */
        u32             max_slotid;             /* Max allowed slotid value */
        u32             highest_used_slotid;    /* sent to server on each SEQ.
                                                 * op for dynamic resizing */
        u32             target_highest_slotid;  /* Server max_slot target */
        u32             server_highest_slotid;  /* Server highest slotid */
        s32             d_target_highest_slotid; /* Derivative */
        s32             d2_target_highest_slotid; /* 2nd derivative */
        unsigned long   generation;             /* Generation counter for
                                                   target_highest_slotid */
        struct completion complete;
        unsigned long   slot_tbl_state;
};

/*
 * Session related parameters
 */
struct nfs4_session {
        struct nfs4_sessionid           sess_id;
        u32                             flags;
        unsigned long                   session_state;
        u32                             hash_alg;
        u32                             ssv_len;

        /* The fore and back channel */
        struct nfs4_channel_attrs       fc_attrs;
        struct nfs4_slot_table          fc_slot_table;
        struct nfs4_channel_attrs       bc_attrs;
        struct nfs4_slot_table          bc_slot_table;
        struct nfs_client               *clp;
};

enum nfs4_session_state {
        NFS4_SESSION_INITING,
        NFS4_SESSION_ESTABLISHED,
};

extern int nfs4_setup_slot_table(struct nfs4_slot_table *tbl,
                unsigned int max_reqs, const char *queue);
extern void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl);
extern struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl);
extern struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid);
extern int nfs4_slot_wait_on_seqid(struct nfs4_slot_table *tbl,
                u32 slotid, u32 seq_nr,
                unsigned long timeout);
extern bool nfs4_try_to_lock_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot);
extern void nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot);
extern void nfs4_slot_tbl_drain_complete(struct nfs4_slot_table *tbl);
bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
                struct nfs4_slot *slot);
void nfs41_wake_slot_table(struct nfs4_slot_table *tbl);

static inline bool nfs4_slot_tbl_draining(struct nfs4_slot_table *tbl)
{
        return !!test_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state);
}

static inline bool nfs4_test_locked_slot(const struct nfs4_slot_table *tbl,
                u32 slotid)
{
        return !!test_bit(slotid, tbl->used_slots);
}

static inline struct nfs4_session *nfs4_get_session(const struct nfs_client *clp)
{
        return clp->cl_session;
}

extern void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
                u32 target_highest_slotid);
extern void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
                struct nfs4_slot *slot,
                struct nfs4_sequence_res *res);

extern int nfs4_setup_session_slot_tables(struct nfs4_session *ses);

extern struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp);
extern void nfs4_destroy_session(struct nfs4_session *session);
extern int nfs4_init_session(struct nfs_client *clp);
extern int nfs4_init_ds_session(struct nfs_client *, unsigned long);

/*
 * Determine if sessions are in use.
 */
static inline int nfs4_has_session(const struct nfs_client *clp)
{
        if (clp->cl_session)
                return 1;
        return 0;
}

static inline int nfs4_has_persistent_session(const struct nfs_client *clp)
{
        if (nfs4_has_session(clp))
                return (clp->cl_session->flags & SESSION4_PERSIST);
        return 0;
}

static inline void nfs4_copy_sessionid(struct nfs4_sessionid *dst,
                const struct nfs4_sessionid *src)
{
        memcpy(dst->data, src->data, NFS4_MAX_SESSIONID_LEN);
}

/*
 * nfs_session_id_hash - calculate the crc32 hash for the session id
 * @session - pointer to session
 */
#define nfs_session_id_hash(sess_id) \
        (~crc32_le(0xFFFFFFFF, &(sess_id)->data[0], sizeof((sess_id)->data)))

#endif /* IS_ENABLED(CONFIG_NFS_V4) */
#endif /* __LINUX_FS_NFS_NFS4SESSION_H */