/* NetBSD: subr_disk.c,v 1.70 2005/08/20 12:00:01 yamt Exp $ */

/* $NetBSD: subr_bufq.c,v 1.27 2019/02/17 23:17:41 bad 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 1.27 2019/02/17 23:17:41 bad Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/bufq.h>
#include <sys/bufq_impl.h>
#include <sys/kmem.h>
#include <sys/sysctl.h>
#include <sys/module.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 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 = 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 = 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);
}
}