/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2004 Poul-Henning Kamp
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Architectural notes:
 *
 * bufobj is a new object which is what buffers hang from in the buffer
 * cache.
 *
 * This used to be vnodes, but we need non-vnode code to be able
 * to use the buffer cache as well, specifically geom classes like
 * raid3 and raid5.
 *
 * All vnodes will contain a bufobj initially, but down the road we may
 * want to only allocate bufobjs when they are needed.  There could be a
 * large number of vnodes in the system which wouldn't need a bufobj during
 * their lifetime.
 *
 * The exact relationship to the vmobject is not determined at this point,
 * it may in fact be that we find them to be two sides of the same object 
 * once things starts to crystalize.
 */

#ifndef _SYS_BUFOBJ_H_
#define _SYS_BUFOBJ_H_

#if defined(_KERNEL) || defined(_KVM_VNODE)

#include <sys/queue.h>
#include <sys/_lock.h>
#include <sys/_rwlock.h>
#include <sys/_pctrie.h>

struct bufobj;
struct buf_ops;

extern struct buf_ops buf_ops_bio;

TAILQ_HEAD(buflists, buf);

/* A Buffer list & trie */
struct bufv {
        struct buflists bv_hd;          /* Sorted blocklist */
        struct pctrie   bv_root;        /* Buf trie */
        int             bv_cnt;         /* Number of buffers */
};

typedef void b_strategy_t(struct bufobj *, struct buf *);
typedef int b_write_t(struct buf *);
typedef int b_sync_t(struct bufobj *, int waitfor);
typedef void b_bdflush_t(struct bufobj *, struct buf *);

struct buf_ops {
        const char      *bop_name;
        b_write_t       *bop_write;
        b_strategy_t    *bop_strategy;
        b_sync_t        *bop_sync;
        b_bdflush_t     *bop_bdflush;
};

#define BO_STRATEGY(bo, bp)     ((bo)->bo_ops->bop_strategy((bo), (bp)))
#define BO_SYNC(bo, w)          ((bo)->bo_ops->bop_sync((bo), (w)))
#define BO_WRITE(bo, bp)        ((bo)->bo_ops->bop_write((bp)))
#define BO_BDFLUSH(bo, bp)      ((bo)->bo_ops->bop_bdflush((bo), (bp)))

/*
 * Locking notes:
 * 'S' is sync_mtx
 * 'v' is the vnode lock which embeds the bufobj.
 * '-' Constant and unchanging after initialization.
 */
struct bufobj {
        struct rwlock   bo_lock;        /* Lock which protects "i" things */
        struct buf_ops  *bo_ops;        /* - Buffer operations */
        struct vm_object *bo_object;    /* v Place to store VM object */
        LIST_ENTRY(bufobj) bo_synclist; /* S dirty vnode list */
        void            *bo_private;    /* private pointer */
        struct bufv     bo_clean;       /* i Clean buffers */
        struct bufv     bo_dirty;       /* i Dirty buffers */
        int             bo_numoutput;   /* i Writes in progress */
        u_int           bo_flag;        /* i Flags */
        int             bo_domain;      /* - Clean queue affinity */
        int             bo_bsize;       /* - Block size for i/o */
};

/*
 * XXX BO_ONWORKLST could be replaced with a check for NULL list elements
 * in v_synclist.
 */
#define BO_ONWORKLST    (1 << 0)        /* On syncer work-list */
#define BO_WWAIT        (1 << 1)        /* Wait for output to complete */
#define BO_DEAD         (1 << 2)        /* Dead; only with INVARIANTS */
#define BO_NOBUFS       (1 << 3)        /* No bufs allowed */
#define BO_NONSTERILE   (1 << 4)        /* Ever called reassignbuf() */

#define BO_LOCKPTR(bo)          (&(bo)->bo_lock)
#define BO_LOCK(bo)             rw_wlock(BO_LOCKPTR((bo)))
#define BO_UNLOCK(bo)           rw_wunlock(BO_LOCKPTR((bo)))
#define BO_RLOCK(bo)            rw_rlock(BO_LOCKPTR((bo)))
#define BO_RUNLOCK(bo)          rw_runlock(BO_LOCKPTR((bo)))
#define ASSERT_BO_WLOCKED(bo)   rw_assert(BO_LOCKPTR((bo)), RA_WLOCKED)
#define ASSERT_BO_LOCKED(bo)    rw_assert(BO_LOCKPTR((bo)), RA_LOCKED)
#define ASSERT_BO_UNLOCKED(bo)  rw_assert(BO_LOCKPTR((bo)), RA_UNLOCKED)

void bufobj_init(struct bufobj *bo, void *priv);
void bufobj_wdrop(struct bufobj *bo);
void bufobj_wref(struct bufobj *bo);
void bufobj_wrefl(struct bufobj *bo);
int bufobj_invalbuf(struct bufobj *bo, int flags, int slpflag, int slptimeo);
int bufobj_wwait(struct bufobj *bo, int slpflag, int timeo);
int bufsync(struct bufobj *bo, int waitfor);
void bufbdflush(struct bufobj *bo, struct buf *bp);

#endif /* defined(_KERNEL) || defined(_KVM_VNODE) */
#endif /* _SYS_BUFOBJ_H_ */