swap_pag.c

open bsd vm device design

/*
 * Copyright (c) 1990 University of Utah.
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 *
 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
 *
 *	@(#)swap_pager.c	8.9 (Berkeley) 3/21/94
 */

/*
 * Quick hack to page to dedicated partition(s).
 * TODO:
 *	Add multiprocessor locks
 *	Deal with async writes in a better fashion
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/map.h>
#include <sys/vnode.h>
#include <sys/malloc.h>

#include <miscfs/specfs/specdev.h>

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/swap_pager.h>

#define NSWSIZES	16	/* size of swtab */
#define MAXDADDRS	64	/* max # of disk addrs for fixed allocations */
#ifndef NPENDINGIO
#define NPENDINGIO	64	/* max # of pending cleans */
#endif

#ifdef DEBUG
int	swpagerdebug = 0x100;
#define	SDB_FOLLOW	0x001
#define SDB_INIT	0x002
#define SDB_ALLOC	0x004
#define SDB_IO		0x008
#define SDB_WRITE	0x010
#define SDB_FAIL	0x020
#define SDB_ALLOCBLK	0x040
#define SDB_FULL	0x080
#define SDB_ANOM	0x100
#define SDB_ANOMPANIC	0x200
#define SDB_CLUSTER	0x400
#define SDB_PARANOIA	0x800
#endif

TAILQ_HEAD(swpclean, swpagerclean);

struct swpagerclean {
	TAILQ_ENTRY(swpagerclean)	spc_list;
	int				spc_flags;
	struct buf			*spc_bp;
	sw_pager_t			spc_swp;
	vm_offset_t			spc_kva;
	vm_page_t			spc_m;
	int				spc_npages;
} swcleanlist[NPENDINGIO];
typedef struct swpagerclean *swp_clean_t;

/* spc_flags values */
#define SPC_FREE	0x00
#define SPC_BUSY	0x01
#define SPC_DONE	0x02
#define SPC_ERROR	0x04

struct swtab {
	vm_size_t st_osize;	/* size of object (bytes) */
	int	  st_bsize;	/* vs. size of swap block (DEV_BSIZE units) */
#ifdef DEBUG
	u_long	  st_inuse;	/* number in this range in use */
	u_long	  st_usecnt;	/* total used of this size */
#endif
} swtab[NSWSIZES+1];

#ifdef DEBUG
int		swap_pager_poip;	/* pageouts in progress */
int		swap_pager_piip;	/* pageins in progress */
#endif

int		swap_pager_maxcluster;	/* maximum cluster size */
int		swap_pager_npendingio;	/* number of pager clean structs */

struct swpclean	swap_pager_inuse;	/* list of pending page cleans */
struct swpclean	swap_pager_free;	/* list of free pager clean structs */
struct pagerlst	swap_pager_list;	/* list of "named" anon regions */

static void 		swap_pager_init __P((void));
static vm_pager_t	swap_pager_alloc
			    __P((caddr_t, vm_size_t, vm_prot_t, vm_offset_t));
static void		swap_pager_clean __P((int));
#ifdef DEBUG
static void		swap_pager_clean_check __P((vm_page_t *, int, int));
#endif
static void		swap_pager_cluster
			    __P((vm_pager_t, vm_offset_t,
				 vm_offset_t *, vm_offset_t *));
static void		swap_pager_dealloc __P((vm_pager_t));
static int		swap_pager_getpage
			    __P((vm_pager_t, vm_page_t *, int, boolean_t));
static boolean_t	swap_pager_haspage __P((vm_pager_t, vm_offset_t));
static int		swap_pager_io __P((sw_pager_t, vm_page_t *, int, int));
static void		swap_pager_iodone __P((struct buf *));
static int		swap_pager_putpage
			    __P((vm_pager_t, vm_page_t *, int, boolean_t));

struct pagerops swappagerops = {
	swap_pager_init,
	swap_pager_alloc,
	swap_pager_dealloc,
	swap_pager_getpage,
	swap_pager_putpage,
	swap_pager_haspage,
	swap_pager_cluster
};

static void
swap_pager_init()
{
	register swp_clean_t spc;
	register int i, bsize;
	extern int dmmin, dmmax;
	int maxbsize;

#ifdef DEBUG
	if (swpagerdebug & (SDB_FOLLOW|SDB_INIT))
		printf("swpg_init()\n");
#endif
	dfltpagerops = &swappagerops;
	TAILQ_INIT(&swap_pager_list);

	/*
	 * Allocate async IO structures.
	 *
	 * XXX it would be nice if we could do this dynamically based on
	 * the value of nswbuf (since we are ultimately limited by that)
	 * but neither nswbuf or malloc has been initialized yet.  So the
	 * structs are statically allocated above.
	 */
	swap_pager_npendingio = NPENDINGIO;

	/*
	 * Initialize clean lists
	 */
	TAILQ_INIT(&swap_pager_inuse);
	TAILQ_INIT(&swap_pager_free);
	for (i = 0, spc = swcleanlist; i < swap_pager_npendingio; i++, spc++) {
		TAILQ_INSERT_TAIL(&swap_pager_free, spc, spc_list);
		spc->spc_flags = SPC_FREE;
	}

	/*
	 * Calculate the swap allocation constants.
	 */
        if (dmmin == 0) {
                dmmin = DMMIN;
		if (dmmin < CLBYTES/DEV_BSIZE)
			dmmin = CLBYTES/DEV_BSIZE;
	}
        if (dmmax == 0)
                dmmax = DMMAX;

	/*
	 * Fill in our table of object size vs. allocation size
	 */
	bsize = btodb(PAGE_SIZE);
	if (bsize < dmmin)
		bsize = dmmin;
	maxbsize = btodb(sizeof(sw_bm_t) * NBBY * PAGE_SIZE);
	if (maxbsize > dmmax)
		maxbsize = dmmax;
	for (i = 0; i < NSWSIZES; i++) {
		swtab[i].st_osize = (vm_size_t) (MAXDADDRS * dbtob(bsize));
		swtab[i].st_bsize = bsize;
		if (bsize <= btodb(MAXPHYS))
			swap_pager_maxcluster = dbtob(bsize);
#ifdef DEBUG
		if (swpagerdebug & SDB_INIT)
			printf("swpg_init: ix %d, size %x, bsize %x\n",
			       i, swtab[i].st_osize, swtab[i].st_bsize);
#endif
		if (bsize >= maxbsize)
			break;
		bsize *= 2;
	}
	swtab[i].st_osize = 0;
	swtab[i].st_bsize = bsize;
}

/*
 * Allocate a pager structure and associated resources.
 * Note that if we are called from the pageout daemon (handle == NULL)
 * we should not wait for memory as it could resulting in deadlock.
 */
static vm_pager_t
swap_pager_alloc(handle, size, prot, foff)
	caddr_t handle;
	register vm_size_t size;
	vm_prot_t prot;
	vm_offset_t foff;
{
	register vm_pager_t pager;
	register sw_pager_t swp;
	struct swtab *swt;
	int waitok;

#ifdef DEBUG
	if (swpagerdebug & (SDB_FOLLOW|SDB_ALLOC))
		printf("swpg_alloc(%x, %x, %x)\n", handle, size, prot);
#endif
	/*
	 * If this is a "named" anonymous region, look it up and
	 * return the appropriate pager if it exists.
	 */
	if (handle) {
		pager = vm_pager_lookup(&swap_pager_list, handle);
		if (pager != NULL) {
			/*
			 * Use vm_object_lookup to gain a reference
			 * to the object and also to remove from the
			 * object cache.
			 */
			if (vm_object_lookup(pager) == NULL)
				panic("swap_pager_alloc: bad object");
			return(pager);
		}
	}
	/*
	 * Pager doesn't exist, allocate swap management resources
	 * and initialize.
	 */
	waitok = handle ? M_WAITOK : M_NOWAIT;
	pager = (vm_pager_t)malloc(sizeof *pager, M_VMPAGER, waitok);
	if (pager == NULL)
		return(NULL);
	swp = (sw_pager_t)malloc(sizeof *swp, M_VMPGDATA, waitok);
	if (swp == NULL) {
#ifdef DEBUG
		if (swpagerdebug & SDB_FAIL)
			printf("swpg_alloc: swpager malloc failed\n");
#endif
		free((caddr_t)pager, M_VMPAGER);
		return(NULL);
	}
	size = round_page(size);
	for (swt = swtab; swt->st_osize; swt++)
		if (size <= swt->st_osize)
			break;
#ifdef DEBUG
	swt->st_inuse++;
	swt->st_usecnt++;
#endif
	swp->sw_osize = size;
	swp->sw_bsize = swt->st_bsize;
	swp->sw_nblocks = (btodb(size) + swp->sw_bsize - 1) / swp->sw_bsize;
	swp->sw_blocks = (sw_blk_t)
		malloc(swp->sw_nblocks*sizeof(*swp->sw_blocks),
		       M_VMPGDATA, M_NOWAIT);
	if (swp->sw_blocks == NULL) {
		free((caddr_t)swp, M_VMPGDATA);
		free((caddr_t)pager, M_VMPAGER);
#ifdef DEBUG
		if (swpagerdebug & SDB_FAIL)
			printf("swpg_alloc: sw_blocks malloc failed\n");
		swt->st_inuse--;
		swt->st_usecnt--;
#endif
		return(FALSE);
	}
	bzero((caddr_t)swp->sw_blocks,
	      swp->sw_nblocks * sizeof(*swp->sw_blocks));
	swp->sw_poip = 0;
	if (handle) {
		vm_object_t object;

		swp->sw_flags = SW_NAMED;
		TAILQ_INSERT_TAIL(&swap_pager_list, pager, pg_list);
		/*
		 * Consistant with other pagers: return with object
		 * referenced.  Can't do this with handle == NULL
		 * since it might be the pageout daemon calling.
		 */
		object = vm_object_allocate(size);
		vm_object_enter(object, pager);
		vm_object_setpager(object, pager, 0, FALSE);
	} else {
		swp->sw_flags = 0;
		pager->pg_list.tqe_next = NULL;
		pager->pg_list.tqe_prev = NULL;
	}
	pager->pg_handle = handle;
	pager->pg_ops = &swappagerops;
	pager->pg_type = PG_SWAP;
	pager->pg_flags = PG_CLUSTERPUT;
	pager->pg_data = swp;

#ifdef DEBUG
	if (swpagerdebug & SDB_ALLOC)
		printf("swpg_alloc: pg_data %x, %x of %x at %x\n",
		       swp, swp->sw_nblocks, swp->sw_bsize, swp->sw_blocks);
#endif
	return(pager);
}

static void
swap_pager_dealloc(pager)
	vm_pager_t pager;
{
	register int i;
	register sw_blk_t bp;
	register sw_pager_t swp;
	struct swtab *swt;
	int s;

#ifdef DEBUG
	/* save panic time state */
	if ((swpagerdebug & SDB_ANOMPANIC) && panicstr)
		return;
	if (swpagerdebug & (SDB_FOLLOW|SDB_ALLOC))
		printf("swpg_dealloc(%x)\n", pager);
#endif
	/*
	 * Remove from list right away so lookups will fail if we
	 * block for pageout completion.
	 */
	swp = (sw_pager_t) pager->pg_data;
	if (swp->sw_flags & SW_NAMED) {
		TAILQ_REMOVE(&swap_pager_list, pager, pg_list);
		swp->sw_flags &= ~SW_NAMED;
	}
#ifdef DEBUG
	for (swt = swtab; swt->st_osize; swt++)
		if (swp->sw_osize <= swt->st_osize)
			break;
	swt->st_inuse--;
#endif

	/*
	 * Wait for all pageouts to finish and remove
	 * all entries from cleaning list.
	 */
	s = splbio();
	while (swp->sw_poip) {
		swp->sw_flags |= SW_WANTED;
		(void) tsleep(swp, PVM, "swpgdealloc", 0);
	}
	splx(s);
	swap_pager_clean(B_WRITE);

	/*
	 * Free left over swap blocks
	 */
	for (i = 0, bp = swp->sw_blocks; i < swp->sw_nblocks; i++, bp++)
		if (bp->swb_block) {
#ifdef DEBUG
			if (swpagerdebug & (SDB_ALLOCBLK|SDB_FULL))
				printf("swpg_dealloc: blk %x\n",
				       bp->swb_block);
#endif
			rmfree(swapmap, swp->sw_bsize, bp->swb_block);
		}
	/*
	 * Free swap management resources
	 */
	free((caddr_t)swp->sw_blocks, M_VMPGDATA);
	free((caddr_t)swp, M_VMPGDATA);
	free((caddr_t)pager, M_VMPAGER);
}

static int
swap_pager_getpage(pager, mlist, npages, sync)
	vm_pager_t pager;
	vm_page_t *mlist;
	int npages;
	boolean_t sync;
{
#ifdef DEBUG
	if (swpagerdebug & SDB_FOLLOW)
		printf("swpg_getpage(%x, %x, %x, %x)\n",
		       pager, mlist, npages, sync);
#endif
	return(swap_pager_io((sw_pager_t)pager->pg_data,
			     mlist, npages, B_READ));
}

static int
swap_pager_putpage(pager, mlist, npages, sync)
	vm_pager_t pager;
	vm_page_t *mlist;
	int npages;
	boolean_t sync;
{
	int flags;

#ifdef DEBUG
	if (swpagerdebug & SDB_FOLLOW)
		printf("swpg_putpage(%x, %x, %x, %x)\n",
		       pager, mlist, npages, sync);
#endif
	if (pager == NULL) {
		swap_pager_clean(B_WRITE);
		return (VM_PAGER_OK);		/* ??? */
	}
	flags = B_WRITE;
	if (!sync)
		flags |= B_ASYNC;
	return(swap_pager_io((sw_pager_t)pager->pg_data,
			     mlist, npages, flags));
}

static boolean_t
swap_pager_haspage(pager, offset)
	vm_pager_t pager;
	vm_offset_t offset;
{
	register sw_pager_t swp;
	register sw_blk_t swb;
	int ix;

#ifdef DEBUG
	if (swpagerdebug & (SDB_FOLLOW|SDB_ALLOCBLK))
		printf("swpg_haspage(%x, %x) ", pager, offset);
#endif
	swp = (sw_pager_t) pager->pg_data;
	ix = offset / dbtob(swp->sw_bsize);
	if (swp->sw_blocks == NULL || ix >= swp->sw_nblocks) {
#ifdef DEBUG
		if (swpagerdebug & (SDB_FAIL|SDB_FOLLOW|SDB_ALLOCBLK))
			printf("swpg_haspage: %x bad offset %x, ix %x\n",
			       swp->sw_blocks, offset, ix);
#endif
		return(FALSE);
	}
	swb = &swp->sw_blocks[ix];
	if (swb->swb_block)
		ix = atop(offset % dbtob(swp->sw_bsize));
#ifdef DEBUG
	if (swpagerdebug & SDB_ALLOCBLK)
		printf("%x blk %x+%x ", swp->sw_blocks, swb->swb_block, ix);
	if (swpagerdebug & (SDB_FOLLOW|SDB_ALLOCBLK))
		printf("-> %c\n",
		       "FT"[swb->swb_block && (swb->swb_mask & (1 << ix))]);
#endif
	if (swb->swb_block && (swb->swb_mask & (1 << ix)))
		return(TRUE);
	return(FALSE);
}

static void
swap_pager_cluster(pager, offset, loffset, hoffset)
	vm_pager_t	pager;
	vm_offset_t	offset;
	vm_offset_t	*loffset;
	vm_offset_t	*hoffset;
{
	sw_pager_t swp;
	register int bsize;
	vm_offset_t loff, hoff;

#ifdef DEBUG
	if (swpagerdebug & (SDB_FOLLOW|SDB_CLUSTER))
		printf("swpg_cluster(%x, %x) ", pager, offset);
#endif
	swp = (sw_pager_t) pager->pg_data;
	bsize = dbtob(swp->sw_bsize);
	if (bsize > swap_pager_maxcluster)