/*      $NetBSD: subr_bufq.c,v 1.29 2026/01/04 02:11:09 riastradh Exp $ */
/*      NetBSD: subr_disk.c,v 1.70 2005/08/20 12:00:01 yamt Exp $       */

/*-
 * Copyright (c) 1996, 1997, 1999, 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Copyright (c) 1982, 1986, 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *      @(#)ufs_disksubr.c      8.5 (Berkeley) 1/21/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_bufq.c,v 1.29 2026/01/04 02:11:09 riastradh Exp $");

#include <sys/param.h>
#include <sys/types.h>

#include <sys/buf.h>
#include <sys/bufq.h>
#include <sys/bufq_impl.h>
#include <sys/kmem.h>
#include <sys/module.h>
#include <sys/sdt.h>
#include <sys/sysctl.h>
#include <sys/systm.h>

#define STRAT_MATCH(id, bs)     (strcmp((id), (bs)->bs_name) == 0)

static void sysctl_kern_bufq_strategies_setup(struct sysctllog **);
static SLIST_HEAD(, bufq_strat) bufq_strat_list =
    SLIST_HEAD_INITIALIZER(bufq_strat_list);

static kmutex_t bufq_mutex;

static struct sysctllog *sysctllog;

void
bufq_init(void)
{

        mutex_init(&bufq_mutex, MUTEX_DEFAULT, IPL_NONE);
        sysctl_kern_bufq_strategies_setup(&sysctllog);
}

int
bufq_register(struct bufq_strat *bs)
{

        mutex_enter(&bufq_mutex);
        SLIST_INSERT_HEAD(&bufq_strat_list, bs, bs_next);
        bs->bs_refcnt = 0;
        mutex_exit(&bufq_mutex);

        return 0;
}

int
bufq_unregister(struct bufq_strat *bs)
{

        mutex_enter(&bufq_mutex);
        if (bs->bs_refcnt != 0) {
                mutex_exit(&bufq_mutex);
                return SET_ERROR(EBUSY);
        }
        SLIST_REMOVE(&bufq_strat_list, bs, bufq_strat, bs_next);
        mutex_exit(&bufq_mutex);

        return 0;
}

/*
 * Create a device buffer queue.
 */
int
bufq_alloc(struct bufq_state **bufqp, const char *strategy, int flags)
{
        struct bufq_strat *bsp, *it;
        struct bufq_state *bufq;
        int error = 0;
        u_int gen;
        bool found_exact;
        char strategy_module_name[MAXPATHLEN];

        KASSERT((flags & BUFQ_EXACT) == 0 || strategy != BUFQ_STRAT_ANY);

        switch (flags & BUFQ_SORT_MASK) {
        case BUFQ_SORT_RAWBLOCK:
        case BUFQ_SORT_CYLINDER:
                break;
        case 0:
                /*
                 * for strategies which don't care about block numbers.
                 * eg. fcfs
                 */
                flags |= BUFQ_SORT_RAWBLOCK;
                break;
        default:
                panic("bufq_alloc: sort out of range");
        }

        /*
         * select strategy.
         * if a strategy specified by flags is found, use it.
         * otherwise, select one with the largest bs_prio.
         */
        mutex_enter(&bufq_mutex);
        do {
                gen = module_gen;
                bsp = NULL;
                found_exact = false;

                SLIST_FOREACH(it, &bufq_strat_list, bs_next) {
                        if (strategy != BUFQ_STRAT_ANY &&
                            STRAT_MATCH(strategy, (it))) {
                                bsp = it;
                                found_exact = true;
                                break;
                        }
                        if (bsp == NULL || (it)->bs_prio > bsp->bs_prio)
                                bsp = it;
                }
                if (strategy == BUFQ_STRAT_ANY || found_exact)
                        break;

                /* Try to autoload the bufq strategy module */
                strlcpy(strategy_module_name, "bufq_",
                        sizeof(strategy_module_name));
                strlcat(strategy_module_name, strategy,
                        sizeof(strategy_module_name));
                mutex_exit(&bufq_mutex);
                (void) module_autoload(strategy_module_name, MODULE_CLASS_BUFQ);
                mutex_enter(&bufq_mutex);
        } while (gen != module_gen);

        if (bsp == NULL) {
                panic("bufq_alloc: no strategy");
        }
        if (strategy != BUFQ_STRAT_ANY && !found_exact) {
                if ((flags & BUFQ_EXACT)) {
                        error = SET_ERROR(ENOENT);
                        mutex_exit(&bufq_mutex);
                        goto out;
                }
#if defined(DEBUG)
                printf("bufq_alloc: '%s' is not available. using '%s'.\n",
                    strategy, bsp->bs_name);
#endif
        }
#if defined(BUFQ_DEBUG)
        /* XXX aprint? */
        printf("bufq_alloc: using '%s'\n", bsp->bs_name);
#endif

        bsp->bs_refcnt++;
        mutex_exit(&bufq_mutex);
        *bufqp = bufq = kmem_zalloc(sizeof(*bufq), KM_SLEEP);
        bufq->bq_flags = flags;
        bufq->bq_strat = bsp;
        (*bsp->bs_initfn)(bufq);

out:
        return error;
}

void
bufq_put(struct bufq_state *bufq, struct buf *bp)
{

        (*bufq->bq_put)(bufq, bp);
}

struct buf *
bufq_get(struct bufq_state *bufq)
{

        return (*bufq->bq_get)(bufq, 1);
}

struct buf *
bufq_peek(struct bufq_state *bufq)
{

        return (*bufq->bq_get)(bufq, 0);
}

struct buf *
bufq_cancel(struct bufq_state *bufq, struct buf *bp)
{

        return (*bufq->bq_cancel)(bufq, bp);
}

/*
 * Drain a device buffer queue.
 */
void
bufq_drain(struct bufq_state *bufq)
{
        struct buf *bp;

        while ((bp = bufq_get(bufq)) != NULL) {
                bp->b_error = SET_ERROR(EIO);
                bp->b_resid = bp->b_bcount;
                biodone(bp);
        }
}

/*
 * Destroy a device buffer queue.
 */
void
bufq_free(struct bufq_state *bufq)
{

        KASSERT(bufq_peek(bufq) == NULL);

        bufq->bq_fini(bufq);

        mutex_enter(&bufq_mutex);
        bufq->bq_strat->bs_refcnt--;
        mutex_exit(&bufq_mutex);
        
        kmem_free(bufq, sizeof(*bufq));
}

/*
 * get a strategy identifier of a buffer queue.
 */
const char *
bufq_getstrategyname(struct bufq_state *bufq)
{

        return bufq->bq_strat->bs_name;
}

/*
 * move all requests on a buffer queue to another.
 */
void
bufq_move(struct bufq_state *dst, struct bufq_state *src)
{
        struct buf *bp;

        while ((bp = bufq_get(src)) != NULL) {
                bufq_put(dst, bp);
        }
}

static int
docopy(char *buf, size_t *bufoffp, size_t buflen,
    const char *datap, size_t datalen)
{
        int error = 0;

        if (buf != NULL && datalen > 0) {

                if (*bufoffp + datalen > buflen) {
                        goto out;
                }
                error = copyout(datap, buf + *bufoffp, datalen);
                if (error) {
                        goto out;
                }
        }
out:
        if (error == 0) {
                *bufoffp += datalen;
        }

        return error;
}

static int
docopystr(char *buf, size_t *bufoffp, size_t buflen, const char *datap)
{

        return docopy(buf, bufoffp, buflen, datap, strlen(datap));
}

static int
docopynul(char *buf, size_t *bufoffp, size_t buflen)
{

        return docopy(buf, bufoffp, buflen, "", 1);
}

/*
 * sysctl function that will print all bufq strategies
 * currently available to the kernel.
 */
static int
sysctl_kern_bufq_strategies(SYSCTLFN_ARGS)
{
        const struct bufq_strat *bq_strat;
        const char *delim = "";
        size_t off = 0;
        size_t buflen = *oldlenp;
        int error;

        SLIST_FOREACH(bq_strat, &bufq_strat_list, bs_next) {
                error = docopystr(oldp, &off, buflen, delim);
                if (error) {
                        goto out;
                }
                error = docopystr(oldp, &off, buflen, (bq_strat)->bs_name);
                if (error) {
                        goto out;
                }
                delim = " ";
        }

        /* In case there are no registered strategies ... */
        if (off == 0) {
                error = docopystr(oldp, &off, buflen, "NULL");
                if (error) {
                        goto out;
                }
        }

        /* NUL terminate */
        error = docopynul(oldp, &off, buflen);
out:
        *oldlenp = off;
        return error;
}

static void
sysctl_kern_bufq_strategies_setup(struct sysctllog **clog)
{
        const struct sysctlnode *node;

        node = NULL;
        sysctl_createv(clog, 0, NULL, &node,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_NODE, "bufq",
                        SYSCTL_DESCR("buffer queue subtree"),
                        NULL, 0, NULL, 0,
                        CTL_KERN, CTL_CREATE, CTL_EOL);
        if (node != NULL) {
                sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_STRING, "strategies",
                        SYSCTL_DESCR("List of bufq strategies present"),
                        sysctl_kern_bufq_strategies, 0, NULL, 0,
                        CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL);
        }
}