/*
 * CDDL HEADER START
 *
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 *
 * CDDL HEADER END
 */
/*
 * Copyright (C) 2017 by Lawrence Livermore National Security, LLC.
 */

#ifndef _SYS_MMP_H
#define _SYS_MMP_H

#include <sys/spa.h>
#include <sys/zfs_context.h>
#include <sys/uberblock_impl.h>

#ifdef  __cplusplus
extern "C" {
#endif

#define MMP_MIN_INTERVAL                100     /* ms */
#define MMP_DEFAULT_INTERVAL            1000    /* ms */
#define MMP_DEFAULT_IMPORT_INTERVALS    20
#define MMP_DEFAULT_FAIL_INTERVALS      10
#define MMP_MIN_FAIL_INTERVALS          2       /* min if != 0 */
#define MMP_IMPORT_SAFETY_FACTOR        200     /* pct */
#define MMP_INTERVAL_OK(interval)       MAX(interval, MMP_MIN_INTERVAL)
#define MMP_FAIL_INTVS_OK(fails)        (fails == 0 ? 0 : MAX(fails, \
                                            MMP_MIN_FAIL_INTERVALS))

typedef struct mmp_thread {
        kmutex_t        mmp_thread_lock; /* protect thread mgmt fields */
        kcondvar_t      mmp_thread_cv;
        kthread_t       *mmp_thread;
        uint8_t         mmp_thread_exiting;
        kmutex_t        mmp_io_lock;    /* protect below */
        hrtime_t        mmp_last_write; /* last successful MMP write */
        uint64_t        mmp_delay;      /* decaying avg ns between MMP writes */
        uberblock_t     mmp_ub;         /* last ub written by sync */
        zio_t           *mmp_zio_root;  /* root of mmp write zios */
        uint64_t        mmp_kstat_id;   /* unique id for next MMP write kstat */
        int             mmp_skip_error; /* reason for last skipped write */
        vdev_t          *mmp_last_leaf; /* last mmp write sent here */
        uint64_t        mmp_leaf_last_gen;      /* last mmp write sent here */
        uint32_t        mmp_seq;        /* intra-second update counter */
} mmp_thread_t;


extern void mmp_init(struct spa *spa);
extern void mmp_fini(struct spa *spa);
extern void mmp_thread_start(struct spa *spa);
extern void mmp_thread_stop(struct spa *spa);
extern void mmp_update_uberblock(struct spa *spa, struct uberblock *ub);
extern void mmp_signal_all_threads(void);

/* Global tuning */
extern ulong_t zfs_multihost_interval;
extern uint_t zfs_multihost_fail_intervals;
extern uint_t zfs_multihost_import_intervals;

#ifdef  __cplusplus
}
#endif

#endif  /* _SYS_MMP_H */