/*	$NetBSD: rf_diskqueue.c,v 1.55.4.2 2021/12/19 16:29:43 martin Exp $	*/
/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: Mark Holland
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

/****************************************************************************
 *
 * rf_diskqueue.c -- higher-level disk queue code
 *
 * the routines here are a generic wrapper around the actual queueing
 * routines.  The code here implements thread scheduling, synchronization,
 * and locking ops (see below) on top of the lower-level queueing code.
 *
 * to support atomic RMW, we implement "locking operations".  When a
 * locking op is dispatched to the lower levels of the driver, the
 * queue is locked, and no further I/Os are dispatched until the queue
 * receives & completes a corresponding "unlocking operation".  This
 * code relies on the higher layers to guarantee that a locking op
 * will always be eventually followed by an unlocking op.  The model
 * is that the higher layers are structured so locking and unlocking
 * ops occur in pairs, i.e.  an unlocking op cannot be generated until
 * after a locking op reports completion.  There is no good way to
 * check to see that an unlocking op "corresponds" to the op that
 * currently has the queue locked, so we make no such attempt.  Since
 * by definition there can be only one locking op outstanding on a
 * disk, this should not be a problem.
 *
 * In the kernel, we allow multiple I/Os to be concurrently dispatched
 * to the disk driver.  In order to support locking ops in this
 * environment, when we decide to do a locking op, we stop dispatching
 * new I/Os and wait until all dispatched I/Os have completed before
 * dispatching the locking op.
 *
 * Unfortunately, the code is different in the 3 different operating
 * states (user level, kernel, simulator).  In the kernel, I/O is
 * non-blocking, and we have no disk threads to dispatch for us.
 * Therefore, we have to dispatch new I/Os to the scsi driver at the
 * time of enqueue, and also at the time of completion.  At user
 * level, I/O is blocking, and so only the disk threads may dispatch
 * I/Os.  Thus at user level, all we can do at enqueue time is enqueue
 * and wake up the disk thread to do the dispatch.
 *
 ****************************************************************************/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rf_diskqueue.c,v 1.55.4.2 2021/12/19 16:29:43 martin Exp $");

#include <dev/raidframe/raidframevar.h>

#include "rf_threadstuff.h"
#include "rf_raid.h"
#include "rf_diskqueue.h"
#include "rf_alloclist.h"
#include "rf_acctrace.h"
#include "rf_etimer.h"
#include "rf_general.h"
#include "rf_debugprint.h"
#include "rf_shutdown.h"
#include "rf_cvscan.h"
#include "rf_sstf.h"
#include "rf_fifo.h"
#include "rf_kintf.h"

#include <sys/buf.h>

static void rf_ShutdownDiskQueueSystem(void *);

#ifndef RF_DEBUG_DISKQUEUE
#define RF_DEBUG_DISKQUEUE 0
#endif

#if RF_DEBUG_DISKQUEUE
#define Dprintf1(s,a)         if (rf_queueDebug) rf_debug_printf(s,(void *)((unsigned long)a),NULL,NULL,NULL,NULL,NULL,NULL,NULL)
#define Dprintf2(s,a,b)       if (rf_queueDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),NULL,NULL,NULL,NULL,NULL,NULL)
#define Dprintf3(s,a,b,c)     if (rf_queueDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),(void *)((unsigned long)c),NULL,NULL,NULL,NULL,NULL)
#else
#define Dprintf1(s,a)
#define Dprintf2(s,a,b)
#define Dprintf3(s,a,b,c)
#endif

/*****************************************************************************
 *
 * the disk queue switch defines all the functions used in the
 * different queueing disciplines queue ID, init routine, enqueue
 * routine, dequeue routine
 *
 ****************************************************************************/

static const RF_DiskQueueSW_t diskqueuesw[] = {
	{"fifo",		/* FIFO */
		rf_FifoCreate,
		rf_FifoEnqueue,
		rf_FifoDequeue,
		rf_FifoPeek,
	rf_FifoPromote},

	{"cvscan",		/* cvscan */
		rf_CvscanCreate,
		rf_CvscanEnqueue,
		rf_CvscanDequeue,
		rf_CvscanPeek,
	rf_CvscanPromote},

	{"sstf",		/* shortest seek time first */
		rf_SstfCreate,
		rf_SstfEnqueue,
		rf_SstfDequeue,
		rf_SstfPeek,
	rf_SstfPromote},

	{"scan",		/* SCAN (two-way elevator) */
		rf_ScanCreate,
		rf_SstfEnqueue,
		rf_ScanDequeue,
		rf_ScanPeek,
	rf_SstfPromote},

	{"cscan",		/* CSCAN (one-way elevator) */
		rf_CscanCreate,
		rf_SstfEnqueue,
		rf_CscanDequeue,
		rf_CscanPeek,
	rf_SstfPromote},

};
#define NUM_DISK_QUEUE_TYPES (sizeof(diskqueuesw)/sizeof(RF_DiskQueueSW_t))


#define RF_MAX_FREE_DQD 256
#define RF_MIN_FREE_DQD  64

/* XXX: scale these... */
#define RF_MAX_FREE_BUFIO 256
#define RF_MIN_FREE_BUFIO  64



/* configures a single disk queue */

static void
rf_ShutdownDiskQueue(void *arg)
{
	RF_DiskQueue_t *diskqueue = arg;

	rf_destroy_mutex2(diskqueue->mutex);
}

int
rf_ConfigureDiskQueue(RF_Raid_t *raidPtr, RF_DiskQueue_t *diskqueue,
		      RF_RowCol_t c, const RF_DiskQueueSW_t *p,
		      RF_SectorCount_t sectPerDisk, dev_t dev,
		      int maxOutstanding, RF_ShutdownList_t **listp,
		      RF_AllocListElem_t *clList)
{
	diskqueue->col = c;
	diskqueue->qPtr = p;
	diskqueue->qHdr = (p->Create) (sectPerDisk, clList, listp);
	diskqueue->dev = dev;
	diskqueue->numOutstanding = 0;
	diskqueue->queueLength = 0;
	diskqueue->maxOutstanding = maxOutstanding;
	diskqueue->curPriority = RF_IO_NORMAL_PRIORITY;
	diskqueue->flags = 0;
	diskqueue->raidPtr = raidPtr;
	diskqueue->rf_cinfo = &raidPtr->raid_cinfo[c];
	rf_init_mutex2(diskqueue->mutex, IPL_VM);
	rf_ShutdownCreate(listp, rf_ShutdownDiskQueue, diskqueue);
	return (0);
}

static void
rf_ShutdownDiskQueueSystem(void *ignored)
{
	pool_destroy(&rf_pools.dqd);
	pool_destroy(&rf_pools.bufio);
}

int
rf_ConfigureDiskQueueSystem(RF_ShutdownList_t **listp)
{

	rf_pool_init(&rf_pools.dqd, sizeof(RF_DiskQueueData_t),
		     "rf_dqd_pl", RF_MIN_FREE_DQD, RF_MAX_FREE_DQD);
	rf_pool_init(&rf_pools.bufio, sizeof(buf_t),
		     "rf_bufio_pl", RF_MIN_FREE_BUFIO, RF_MAX_FREE_BUFIO);
	rf_ShutdownCreate(listp, rf_ShutdownDiskQueueSystem, NULL);

	return (0);
}

int
rf_ConfigureDiskQueues(RF_ShutdownList_t **listp, RF_Raid_t *raidPtr,
		       RF_Config_t *cfgPtr)
{
	RF_DiskQueue_t *diskQueues, *spareQueues;
	const RF_DiskQueueSW_t *p;
	RF_RowCol_t r,c;
	int     rc, i;

	raidPtr->maxQueueDepth = cfgPtr->maxOutstandingDiskReqs;

	for (p = NULL, i = 0; i < NUM_DISK_QUEUE_TYPES; i++) {
		if (!strcmp(diskqueuesw[i].queueType, cfgPtr->diskQueueType)) {
			p = &diskqueuesw[i];
			break;
		}
	}
	if (p == NULL) {
		RF_ERRORMSG2("Unknown queue type \"%s\".  Using %s\n", cfgPtr->diskQueueType, diskqueuesw[0].queueType);
		p = &diskqueuesw[0];
	}
	raidPtr->qType = p;

	diskQueues = RF_MallocAndAdd(
	    (raidPtr->numCol + RF_MAXSPARE) * sizeof(*diskQueues),
	    raidPtr->cleanupList);
	if (diskQueues == NULL)
		return (ENOMEM);
	raidPtr->Queues = diskQueues;

	for (c = 0; c < raidPtr->numCol; c++) {
		rc = rf_ConfigureDiskQueue(raidPtr, &diskQueues[c],
					   c, p,
					   raidPtr->sectorsPerDisk,
					   raidPtr->Disks[c].dev,
					   cfgPtr->maxOutstandingDiskReqs,
					   listp, raidPtr->cleanupList);
		if (rc)
			return (rc);
	}

	spareQueues = &raidPtr->Queues[raidPtr->numCol];
	for (r = 0; r < raidPtr->numSpare; r++) {
		rc = rf_ConfigureDiskQueue(raidPtr, &spareQueues[r],
					   raidPtr->numCol + r, p,
					   raidPtr->sectorsPerDisk,
					   raidPtr->Disks[raidPtr->numCol + r].dev,
					   cfgPtr->maxOutstandingDiskReqs, listp,
					   raidPtr->cleanupList);
		if (rc)
			return (rc);
	}
	return (0);
}
/* Enqueue a disk I/O
 *
 * In the kernel, I/O is non-blocking and so we'd like to have multiple
 * I/Os outstanding on the physical disks when possible.
 *
 * when any request arrives at a queue, we have two choices:
 *    dispatch it to the lower levels
 *    queue it up
 *
 * kernel rules for when to do what:
 *    unlocking req  :  always dispatch it
 *    normal req     :  queue empty => dispatch it & set priority
 *                      queue not full & priority is ok => dispatch it
 *                      else queue it
 */
void
rf_DiskIOEnqueue(RF_DiskQueue_t *queue, RF_DiskQueueData_t *req, int pri)
{
	RF_ETIMER_START(req->qtime);
	RF_ASSERT(req->type == RF_IO_TYPE_NOP || req->numSector);
	req->priority = pri;

#if RF_DEBUG_DISKQUEUE
	if (rf_queueDebug && (req->numSector == 0)) {
		printf("Warning: Enqueueing zero-sector access\n");
	}
#endif
	RF_LOCK_QUEUE_MUTEX(queue, "DiskIOEnqueue");
	if (RF_OK_TO_DISPATCH(queue, req)) {
		Dprintf2("Dispatching pri %d regular op to c %d (ok to dispatch)\n", pri, queue->col);
		rf_DispatchKernelIO(queue, req);
	} else {
		queue->queueLength++;	/* increment count of number of requests waiting in this queue */
		Dprintf2("Enqueueing pri %d regular op to c %d (not ok to dispatch)\n", pri, queue->col);
		req->queue = (void *) queue;
		(queue->qPtr->Enqueue) (queue->qHdr, req, pri);
	}
	RF_UNLOCK_QUEUE_MUTEX(queue, "DiskIOEnqueue");
}


/* get the next set of I/Os started */
void
rf_DiskIOComplete(RF_DiskQueue_t *queue, RF_DiskQueueData_t *req, int status)
{
	int     done = 0;

	RF_LOCK_QUEUE_MUTEX(queue, "DiskIOComplete");
	queue->numOutstanding--;
	RF_ASSERT(queue->numOutstanding >= 0);

	/* dispatch requests to the disk until we find one that we can't. */
	/* no reason to continue once we've filled up the queue */
	/* no reason to even start if the queue is locked */

	while (!done && !RF_QUEUE_FULL(queue)) {
		req = (queue->qPtr->Dequeue) (queue->qHdr);
		if (req) {
			Dprintf2("DiskIOComplete: extracting pri %d req from queue at c %d\n", req->priority, queue->col);
			queue->queueLength--;	/* decrement count of number of requests waiting in this queue */
			RF_ASSERT(queue->queueLength >= 0);
			if (RF_OK_TO_DISPATCH(queue, req)) {
				Dprintf2("DiskIOComplete: dispatching pri %d regular req to c %d (ok to dispatch)\n", req->priority, queue->col);
				rf_DispatchKernelIO(queue, req);
			} else {	
				/* we can't dispatch it, so just re-enqueue it.  
				   potential trouble here if disk queues batch reqs */
				Dprintf2("DiskIOComplete: re-enqueueing pri %d regular req to c %d\n", req->priority, queue->col);
				queue->queueLength++;
				(queue->qPtr->Enqueue) (queue->qHdr, req, req->priority);
				done = 1;
			}
		} else {	
			Dprintf1("DiskIOComplete: no more requests to extract.\n", "");
			done = 1;
		}
	}

	RF_UNLOCK_QUEUE_MUTEX(queue, "DiskIOComplete");
}
/* promotes accesses tagged with the given parityStripeID from low priority
 * to normal priority.  This promotion is optional, meaning that a queue
 * need not implement it.  If there is no promotion routine associated with
 * a queue, this routine does nothing and returns -1.
 */
int
rf_DiskIOPromote(RF_DiskQueue_t *queue, RF_StripeNum_t parityStripeID,
		 RF_ReconUnitNum_t which_ru)
{
	int     retval;

	if (!queue->qPtr->Promote)
		return (-1);
	RF_LOCK_QUEUE_MUTEX(queue, "DiskIOPromote");
	retval = (queue->qPtr->Promote) (queue->qHdr, parityStripeID, which_ru);
	RF_UNLOCK_QUEUE_MUTEX(queue, "DiskIOPromote");
	return (retval);
}

RF_DiskQueueData_t *
rf_CreateDiskQueueData(RF_IoType_t typ, RF_SectorNum_t ssect,
		       RF_SectorCount_t nsect, void *bf,
		       RF_StripeNum_t parityStripeID,
		       RF_ReconUnitNum_t which_ru,
		       int (*wakeF) (void *, int), void *arg,
		       RF_AccTraceEntry_t *tracerec, RF_Raid_t *raidPtr,
		       RF_DiskQueueDataFlags_t flags, void *kb_proc,
		       int waitflag)
{
	RF_DiskQueueData_t *p;

	p = pool_get(&rf_pools.dqd, PR_WAITOK | PR_ZERO);
	KASSERT(p != NULL);

	/* Obtain a buffer from our own pool.  It is possible for the
	   regular getiobuf() to run out of memory and return NULL.
	   We need to guarantee that never happens, as RAIDframe
	   doesn't have a good way to recover if memory allocation
	   fails here.
	*/
	p->bp = pool_get(&rf_pools.bufio, PR_WAITOK | PR_ZERO);
	KASSERT(p->bp != NULL);
	
	buf_init(p->bp);
		
	SET(p->bp->b_cflags, BC_BUSY);	/* mark buffer busy */

	p->sectorOffset = ssect + rf_protectedSectors;
	p->numSector = nsect;
	p->type = typ;
	p->buf = bf;
	p->parityStripeID = parityStripeID;
	p->which_ru = which_ru;
	p->CompleteFunc = wakeF;
	p->argument = arg;
	p->next = NULL;
	p->tracerec = tracerec;
	p->priority = RF_IO_NORMAL_PRIORITY;
	p->raidPtr = raidPtr;
	p->flags = flags;
	p->b_proc = kb_proc;
	return (p);
}

void
rf_FreeDiskQueueData(RF_DiskQueueData_t *p)
{

	buf_destroy(p->bp);

	pool_put(&rf_pools.bufio, p->bp);
	pool_put(&rf_pools.dqd, p);
}