freebsd-nq/sys/kern/vfs_aio.c

/*
 * Copyright (c) 1997 John S. Dyson.  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. John S. Dyson's name may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * DISCLAIMER:  This code isn't warranted to do anything useful.  Anything
 * bad that happens because of using this software isn't the responsibility
 * of the author.  This software is distributed AS-IS.
 *
 * $Id: vfs_aio.c,v 1.17 1997/12/01 07:01:45 dyson Exp $
 */

/*
 * This file contains support for the POSIX.4 AIO/LIO facility.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/lock.h>
#include <sys/unistd.h>
#include <sys/proc.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <sys/conf.h>
#include <miscfs/specfs/specdev.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_zone.h>
#include <sys/aio.h>
#include <sys/shm.h>
#include <sys/user.h>

#include <machine/cpu.h>

static	int jobrefid;

#define JOBST_NULL			0x0
#define	JOBST_JOBQPROC		0x1
#define JOBST_JOBQGLOBAL	0x2
#define JOBST_JOBRUNNING	0x3
#define JOBST_JOBFINISHED	0x4
#define	JOBST_JOBQBUF		0x5
#define	JOBST_JOBBFINISHED	0x6

#ifndef MAX_AIO_PER_PROC
#define MAX_AIO_PER_PROC	32
#endif

#ifndef MAX_AIO_QUEUE_PER_PROC
#define MAX_AIO_QUEUE_PER_PROC	256 /* Bigger than AIO_LISTIO_MAX */
#endif

#ifndef MAX_AIO_PROCS
#define MAX_AIO_PROCS		32
#endif

#ifndef MAX_AIO_QUEUE
#define	MAX_AIO_QUEUE		1024 /* Bigger than AIO_LISTIO_MAX */
#endif

#ifndef TARGET_AIO_PROCS
#define TARGET_AIO_PROCS	0
#endif

#ifndef MAX_BUF_AIO
#define MAX_BUF_AIO 16
#endif

#ifndef AIOD_TIMEOUT_DEFAULT
#define	AIOD_TIMEOUT_DEFAULT (10 * hz)
#endif

#ifndef AIOD_LIFETIME_DEFAULT
#define AIOD_LIFETIME_DEFAULT (30 * hz)
#endif

int max_aio_procs = MAX_AIO_PROCS;
int num_aio_procs = 0;
int target_aio_procs = TARGET_AIO_PROCS;
int max_queue_count = MAX_AIO_QUEUE;
int num_queue_count = 0;
int num_buf_aio = 0;
int num_aio_resv_start = 0;
int aiod_timeout;
int aiod_lifetime;

int max_aio_per_proc = MAX_AIO_PER_PROC,
	max_aio_queue_per_proc=MAX_AIO_QUEUE_PER_PROC;

int max_buf_aio = MAX_BUF_AIO;

SYSCTL_NODE(_vfs, OID_AUTO, aio, CTLFLAG_RW, 0, "AIO mgmt");

SYSCTL_INT(_vfs_aio, OID_AUTO, max_aio_per_proc,
	CTLFLAG_RW, &max_aio_per_proc, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, max_aio_queue_per_proc,
	CTLFLAG_RW, &max_aio_queue_per_proc, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, max_aio_procs,
	CTLFLAG_RW, &max_aio_procs, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, num_aio_procs,
	CTLFLAG_RD, &num_aio_procs, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, num_queue_count,
	CTLFLAG_RD, &num_queue_count, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, max_aio_queue,
	CTLFLAG_RW, &max_queue_count, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, target_aio_procs,
	CTLFLAG_RW, &target_aio_procs, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, max_buf_aio,
	CTLFLAG_RW, &max_buf_aio, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, num_buf_aio,
	CTLFLAG_RD, &num_buf_aio, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, aiod_lifetime,
	CTLFLAG_RW, &aiod_lifetime, 0, "");

SYSCTL_INT(_vfs_aio, OID_AUTO, aiod_timeout,
	CTLFLAG_RW, &aiod_timeout, 0, "");


/*
 * Job queue item
 */

#define AIOCBLIST_CANCELLED	0x1
#define AIOCBLIST_RUNDOWN	0x4
#define AIOCBLIST_ASYNCFREE	0x8
#define AIOCBLIST_DONE		0x10

struct aiocblist {
	TAILQ_ENTRY (aiocblist) list;		/* List of jobs */
	TAILQ_ENTRY (aiocblist) plist;		/* List of jobs for proc */
	int	jobflags;
	int	jobstate;
	int inputcharge, outputcharge;
	struct	buf *bp;				/* buffer pointer */
	struct	proc *userproc;			/* User process */
	struct	aioproclist	*jobaioproc;	/* AIO process descriptor */
	struct	aio_liojob	*lio;		/* optional lio job */
	struct	aiocb *uuaiocb;			/* pointer in userspace of aiocb */
	struct	aiocb uaiocb;			/* Kernel I/O control block */
};


/*
 * AIO process info
 */
#define AIOP_FREE	0x1			/* proc on free queue */
#define AIOP_SCHED	0x2			/* proc explicitly scheduled */

struct aioproclist {
	int aioprocflags;			/* AIO proc flags */
	TAILQ_ENTRY(aioproclist) list;		/* List of processes */
	struct proc *aioproc;			/* The AIO thread */
	TAILQ_HEAD (,aiocblist) jobtorun;	/* suggested job to run */
};

/*
 * data-structure for lio signal management
 */
struct aio_liojob {
	int lioj_flags;
	int	lioj_buffer_count;
	int	lioj_buffer_finished_count;
	int	lioj_queue_count;
	int	lioj_queue_finished_count;
	struct sigevent lioj_signal;	/* signal on all I/O done */
	TAILQ_ENTRY (aio_liojob) lioj_list;
	struct kaioinfo *lioj_ki;
};
#define	LIOJ_SIGNAL			0x1 /* signal on all done (lio) */
#define	LIOJ_SIGNAL_POSTED	0x2	/* signal has been posted */

/*
 * per process aio data structure
 */
struct kaioinfo {
	int	kaio_flags;			/* per process kaio flags */
	int	kaio_maxactive_count;	/* maximum number of AIOs */
	int	kaio_active_count;	/* number of currently used AIOs */
	int	kaio_qallowed_count;	/* maxiumu size of AIO queue */
	int	kaio_queue_count;	/* size of AIO queue */
	int	kaio_ballowed_count;	/* maximum number of buffers */
	int	kaio_queue_finished_count;	/* number of daemon jobs finished */
	int	kaio_buffer_count;	/* number of physio buffers */
	int	kaio_buffer_finished_count;	/* count of I/O done */
	struct proc *kaio_p;			/* process that uses this kaio block */
	TAILQ_HEAD (,aio_liojob) kaio_liojoblist;	/* list of lio jobs */
	TAILQ_HEAD (,aiocblist)	kaio_jobqueue;	/* job queue for process */
	TAILQ_HEAD (,aiocblist)	kaio_jobdone;	/* done queue for process */
	TAILQ_HEAD (,aiocblist)	kaio_bufqueue;	/* buffer job queue for process */
	TAILQ_HEAD (,aiocblist)	kaio_bufdone;	/* buffer done queue for process */
};

#define KAIO_RUNDOWN 0x1		/* process is being run down */
#define KAIO_WAKEUP 0x2			/* wakeup process when there is a significant
								   event */


TAILQ_HEAD (,aioproclist) aio_freeproc, aio_activeproc;
TAILQ_HEAD(,aiocblist) aio_jobs;			/* Async job list */
TAILQ_HEAD(,aiocblist) aio_bufjobs;			/* Phys I/O job list */
TAILQ_HEAD(,aiocblist) aio_freejobs;		/* Pool of free jobs */

static void aio_init_aioinfo(struct proc *p) ;
static void aio_onceonly(void *) ;
static int aio_free_entry(struct aiocblist *aiocbe);
static void aio_process(struct aiocblist *aiocbe);
static int aio_newproc(void) ;
static int aio_aqueue(struct proc *p, struct aiocb *job, int type) ;
static void aio_physwakeup(struct buf *bp);
static int aio_fphysio(struct proc *p, struct aiocblist *aiocbe, int type);
static int aio_qphysio(struct proc *p, struct aiocblist *iocb);
static void aio_daemon(void *uproc);

SYSINIT(aio, SI_SUB_VFS, SI_ORDER_ANY, aio_onceonly, NULL);

static vm_zone_t kaio_zone=0, aiop_zone=0,
	aiocb_zone=0, aiol_zone=0, aiolio_zone=0;

/*
 * Single AIOD vmspace shared amongst all of them
 */
static struct vmspace *aiovmspace = NULL;

/*
 * Startup initialization
 */
void
aio_onceonly(void *na)
{
	TAILQ_INIT(&aio_freeproc);
	TAILQ_INIT(&aio_activeproc);
	TAILQ_INIT(&aio_jobs);
	TAILQ_INIT(&aio_bufjobs);
	TAILQ_INIT(&aio_freejobs);
	kaio_zone = zinit("AIO", sizeof (struct kaioinfo), 0, 0, 1);
	aiop_zone = zinit("AIOP", sizeof (struct aioproclist), 0, 0, 1);
	aiocb_zone = zinit("AIOCB", sizeof (struct aiocblist), 0, 0, 1);
	aiol_zone = zinit("AIOL", AIO_LISTIO_MAX * sizeof (int), 0, 0, 1);
	aiolio_zone = zinit("AIOLIO",
		AIO_LISTIO_MAX * sizeof (struct aio_liojob), 0, 0, 1);
	aiod_timeout = AIOD_TIMEOUT_DEFAULT;
	aiod_lifetime = AIOD_LIFETIME_DEFAULT;
	jobrefid = 1;
}

/*
 * Init the per-process aioinfo structure.
 * The aioinfo limits are set per-process for user limit (resource) management.
 */
void
aio_init_aioinfo(struct proc *p)
{
	struct kaioinfo *ki;
	if (p->p_aioinfo == NULL) {
		ki = zalloc(kaio_zone);
		p->p_aioinfo = ki;
		ki->kaio_flags = 0;
		ki->kaio_maxactive_count = max_aio_per_proc;
		ki->kaio_active_count = 0;
		ki->kaio_qallowed_count = max_aio_queue_per_proc;
		ki->kaio_queue_count = 0;
		ki->kaio_ballowed_count = max_buf_aio;
		ki->kaio_buffer_count = 0;
		ki->kaio_buffer_finished_count = 0;
		ki->kaio_p = p;
		TAILQ_INIT(&ki->kaio_jobdone);
		TAILQ_INIT(&ki->kaio_jobqueue);
		TAILQ_INIT(&ki->kaio_bufdone);
		TAILQ_INIT(&ki->kaio_bufqueue);
		TAILQ_INIT(&ki->kaio_liojoblist);
	}
}

/*
 * Free a job entry.  Wait for completion if it is currently
 * active, but don't delay forever.  If we delay, we return
 * a flag that says that we have to restart the queue scan.
 */
int
aio_free_entry(struct aiocblist *aiocbe)
{
	struct kaioinfo *ki;
	struct aioproclist *aiop;
	struct aio_liojob *lj;
	struct proc *p;
	int error;
	int s;

	if (aiocbe->jobstate == JOBST_NULL)
		panic("aio_free_entry: freeing already free job");

	p = aiocbe->userproc;
	ki = p->p_aioinfo;
	lj = aiocbe->lio;
	if (ki == NULL)
		panic("aio_free_entry: missing p->p_aioinfo");

	if (aiocbe->jobstate == JOBST_JOBRUNNING) {
		if (aiocbe->jobflags & AIOCBLIST_ASYNCFREE)
			return 0;
		aiocbe->jobflags |= AIOCBLIST_RUNDOWN;
		tsleep(aiocbe, PRIBIO|PCATCH, "jobwai", 0);
	}
	aiocbe->jobflags &= ~AIOCBLIST_ASYNCFREE;

	if (aiocbe->bp == NULL) {
		if (ki->kaio_queue_count <= 0)
			panic("aio_free_entry: process queue size <= 0");
		if (num_queue_count <= 0)
			panic("aio_free_entry: system wide queue size <= 0");
	
		if(lj) {
			lj->lioj_queue_count--;
			if (aiocbe->jobflags & AIOCBLIST_DONE)
				lj->lioj_queue_finished_count--;
		}
		ki->kaio_queue_count--;
		if (aiocbe->jobflags & AIOCBLIST_DONE)
			ki->kaio_queue_finished_count--;
		num_queue_count--;

	} else {
		if(lj) {
			lj->lioj_buffer_count--;
			if (aiocbe->jobflags & AIOCBLIST_DONE)
				lj->lioj_buffer_finished_count--;
		}
		if (aiocbe->jobflags & AIOCBLIST_DONE)
			ki->kaio_buffer_finished_count--;
		ki->kaio_buffer_count--;
		num_buf_aio--;

	}

	if ((ki->kaio_flags & KAIO_WAKEUP) ||
		(ki->kaio_flags & KAIO_RUNDOWN) &&
		((ki->kaio_buffer_count == 0) && (ki->kaio_queue_count == 0))) {
		ki->kaio_flags &= ~KAIO_WAKEUP;
		wakeup(p);
	}

	if ( aiocbe->jobstate == JOBST_JOBQBUF) {
		if ((error = aio_fphysio(p, aiocbe, 1)) != 0)
			return error;
		if (aiocbe->jobstate != JOBST_JOBBFINISHED)
			panic("aio_free_entry: invalid physio finish-up state");
		s = splbio();
		TAILQ_REMOVE(&ki->kaio_bufdone, aiocbe, plist);
		splx(s);
	} else if ( aiocbe->jobstate == JOBST_JOBQPROC) {
		aiop = aiocbe->jobaioproc;
		TAILQ_REMOVE(&aiop->jobtorun, aiocbe, list);
	} else if ( aiocbe->jobstate == JOBST_JOBQGLOBAL) {
		TAILQ_REMOVE(&aio_jobs, aiocbe, list);
	} else if ( aiocbe->jobstate == JOBST_JOBFINISHED) {
		TAILQ_REMOVE(&ki->kaio_jobdone, aiocbe, plist);
	} else if ( aiocbe->jobstate == JOBST_JOBBFINISHED) {
		s = splbio();
		TAILQ_REMOVE(&ki->kaio_bufdone, aiocbe, plist);
		splx(s);
		if (aiocbe->bp) {
			vunmapbuf(aiocbe->bp);
			relpbuf(aiocbe->bp);
			aiocbe->bp = NULL;
		}
	}
	if (lj && (lj->lioj_buffer_count == 0) && (lj->lioj_queue_count == 0)) {
		TAILQ_REMOVE(&ki->kaio_liojoblist, lj, lioj_list);
		zfree(aiolio_zone, lj);
	}
	TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
	aiocbe->jobstate = JOBST_NULL;
	return 0;
}

/*
 * Rundown the jobs for a given process.  
 */
void
aio_proc_rundown(struct proc *p)
{
	int s;
	struct kaioinfo *ki;
	struct aio_liojob *lj, *ljn;
	struct aiocblist *aiocbe, *aiocbn;
	
	ki = p->p_aioinfo;
	if (ki == NULL)
		return;

	ki->kaio_flags |= LIOJ_SIGNAL_POSTED;
	while ((ki->kaio_active_count > 0) ||
		(ki->kaio_buffer_count > ki->kaio_buffer_finished_count)) {
		ki->kaio_flags |= KAIO_RUNDOWN;
		if (tsleep(p, PRIBIO, "kaiowt", aiod_timeout))
			break;
	}

restart1:
	for ( aiocbe = TAILQ_FIRST(&ki->kaio_jobdone);
		aiocbe;
		aiocbe = aiocbn) {
		aiocbn = TAILQ_NEXT(aiocbe, plist);
		if (aio_free_entry(aiocbe))
			goto restart1;
	}

restart2:
	for ( aiocbe = TAILQ_FIRST(&ki->kaio_jobqueue);
		aiocbe;
		aiocbe = aiocbn) {
		aiocbn = TAILQ_NEXT(aiocbe, plist);
		if (aio_free_entry(aiocbe))
			goto restart2;
	}

/*
 * Note the use of lots of splbio here, trying to avoid
 * splbio for long chains of I/O.  Probably unnecessary.
 */

restart3:
	s = splbio();
	while (TAILQ_FIRST(&ki->kaio_bufqueue)) {
		ki->kaio_flags |= KAIO_WAKEUP;
		tsleep (p, PRIBIO, "aioprn", 0);	
		splx(s);
		goto restart3;
	}
	splx(s);

restart4:
	s = splbio();
	for ( aiocbe = TAILQ_FIRST(&ki->kaio_bufdone);
		aiocbe;
		aiocbe = aiocbn) {
		aiocbn = TAILQ_NEXT(aiocbe, plist);
		if (aio_free_entry(aiocbe)) {
			splx(s);
			goto restart4;
		}
	}
	splx(s);

	for ( lj = TAILQ_FIRST(&ki->kaio_liojoblist);
		  lj;
		  lj = ljn) {
			ljn = TAILQ_NEXT(lj, lioj_list);
			if ((lj->lioj_buffer_count == 0) && (lj->lioj_queue_count == 0)) {
				TAILQ_REMOVE(&ki->kaio_liojoblist, lj, lioj_list);
				zfree(aiolio_zone, lj);
			} else {
#if defined(DIAGNOSTIC)
				printf("LIO job not cleaned up: B:%d, BF:%d, Q:%d, QF:%d\n",
					lj->lioj_buffer_count, lj->lioj_buffer_finished_count,
					lj->lioj_queue_count, lj->lioj_queue_finished_count);
#endif
			}
	}

	zfree(kaio_zone, ki);
	p->p_aioinfo = NULL;
}

/*
 * Select a job to run (called by an AIO daemon)
 */
static struct aiocblist *
aio_selectjob(struct aioproclist *aiop)
{

	struct aiocblist *aiocbe;

	aiocbe = TAILQ_FIRST(&aiop->jobtorun);
	if (aiocbe) {
		TAILQ_REMOVE(&aiop->jobtorun, aiocbe, list);
		return aiocbe;
	}

	for (aiocbe = TAILQ_FIRST(&aio_jobs);
		aiocbe;
		aiocbe = TAILQ_NEXT(aiocbe, list)) {
		struct kaioinfo *ki;
		struct proc *userp;

		userp = aiocbe->userproc;
		ki = userp->p_aioinfo;

		if (ki->kaio_active_count < ki->kaio_maxactive_count) {
			TAILQ_REMOVE(&aio_jobs, aiocbe, list);
			return aiocbe;
		}
	}

	return NULL;
}

/*
 * The AIO processing activity.  This is the code that does the
 * I/O request for the non-physio version of the operations.  The
 * normal vn operations are used, and this code should work in
 * all instances for every type of file, including pipes, sockets,
 * fifos, and regular files.
 */
void
aio_process(struct aiocblist *aiocbe)
{
	struct filedesc *fdp;
	struct proc *userp, *mycp;
	struct aiocb *cb;
	struct file *fp;
	struct uio auio;
	struct iovec aiov;
	unsigned int fd;
	int cnt;
	static nperline=0;
	int error;
	off_t offset;
	int oublock_st, oublock_end;
	int inblock_st, inblock_end;

	userp = aiocbe->userproc;
	cb = &aiocbe->uaiocb;

	mycp = curproc;

	fdp = mycp->p_fd;
	fd = cb->aio_fildes;
	fp = fdp->fd_ofiles[fd];

	aiov.iov_base = cb->aio_buf;
	aiov.iov_len = cb->aio_nbytes;

	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_offset = offset = cb->aio_offset;
	auio.uio_resid = cb->aio_nbytes;
	cnt = cb->aio_nbytes;
	auio.uio_segflg = UIO_USERSPACE;
	auio.uio_procp = mycp;

	inblock_st = mycp->p_stats->p_ru.ru_inblock;
	oublock_st = mycp->p_stats->p_ru.ru_oublock;
	if (cb->aio_lio_opcode == LIO_READ) {
		auio.uio_rw = UIO_READ;
		error = (*fp->f_ops->fo_read)(fp, &auio, fp->f_cred);
	} else {
		auio.uio_rw = UIO_WRITE;
		error = (*fp->f_ops->fo_write)(fp, &auio, fp->f_cred);
	}
	inblock_end = mycp->p_stats->p_ru.ru_inblock;
	oublock_end = mycp->p_stats->p_ru.ru_oublock;

	aiocbe->inputcharge = inblock_end - inblock_st;
	aiocbe->outputcharge = oublock_end - oublock_st;

	if (error) {
		if (auio.uio_resid != cnt) {
			if (error == ERESTART || error == EINTR || error == EWOULDBLOCK)
				error = 0;
			if ((error == EPIPE) && (cb->aio_lio_opcode == LIO_WRITE))
				psignal(userp, SIGPIPE);
		}
	}

	cnt -= auio.uio_resid;
	cb->_aiocb_private.error = error;
	cb->_aiocb_private.status = cnt;
	
	return;

}

/*
 * The AIO daemon, most of the actual work is done in aio_process,
 * but the setup (and address space mgmt) is done in this routine.
 */
static void
aio_daemon(void *uproc)
{
	int s;
	struct aioproclist *aiop;
	struct vmspace *myvm, *aiovm;
	struct proc *mycp;

	/*
	 * Local copies of curproc (cp) and vmspace (myvm)
	 */
	mycp = curproc;
	myvm = mycp->p_vmspace;

	/*
	 * We manage to create only one VM space for all AIOD processes.
	 * The VM space for the first AIOD created becomes the shared VM
	 * space for all of them.  We add an additional reference count,
	 * even for the first AIOD, so the address space does not go away,
	 * and we continue to use that original VM space even if the first
	 * AIOD exits.
	 */
	if ((aiovm = aiovmspace) == NULL) {
		aiovmspace = myvm;
		myvm->vm_refcnt++;
		/*
		 * Remove userland cruft from address space.
		 */
		if (myvm->vm_shm)
			shmexit(mycp);
		pmap_remove_pages(&myvm->vm_pmap, 0, USRSTACK);
		vm_map_remove(&myvm->vm_map, 0, USRSTACK);
		myvm->vm_tsize = 0;
		myvm->vm_dsize = 0;
		myvm->vm_ssize = 0;
	} else {
		aiovm->vm_refcnt++;
		mycp->p_vmspace = aiovm;
		pmap_activate(mycp);
		vmspace_free(myvm);
		myvm = aiovm;
	}

	if (mycp->p_textvp) {
		vrele(mycp->p_textvp);
		mycp->p_textvp = NULL;
	}

	/*
	 * Allocate and ready the aio control info.  There is one
	 * aiop structure per daemon.
	 */
	aiop = zalloc(aiop_zone);
	aiop->aioproc = mycp;
	aiop->aioprocflags |= AIOP_FREE;
	TAILQ_INIT(&aiop->jobtorun);

	/*
	 * Place thread (lightweight process) onto the AIO free thread list
	 */
	if (TAILQ_EMPTY(&aio_freeproc))
		wakeup(&aio_freeproc);
	TAILQ_INSERT_HEAD(&aio_freeproc, aiop, list);

	/*
	 * Make up a name for the daemon
	 */
	strcpy(mycp->p_comm, "aiod");

	/*
	 * Get rid of our current filedescriptors.  AIOD's don't need any
	 * filedescriptors, except as temporarily inherited from the client.
	 * Credentials are also cloned, and made equivalent to "root."
	 */
	fdfree(mycp);
	mycp->p_fd = NULL;
	mycp->p_ucred = crcopy(mycp->p_ucred);
	mycp->p_ucred->cr_uid = 0;
	mycp->p_ucred->cr_ngroups = 1;
	mycp->p_ucred->cr_groups[0] = 1;

	/*
	 * The daemon resides in it's own pgrp.
	 */
	enterpgrp(mycp, mycp->p_pid, 1);

	/*
	 * Mark special process type
	 */
	mycp->p_flag |= P_SYSTEM|P_KTHREADP;

	/*
	 * Wakeup parent process.  (Parent sleeps to keep from blasting away
	 * creating to many daemons.)
	 */
	wakeup(mycp);

	while(1) {
		struct proc *curcp;
		struct	aiocblist *aiocbe;

		/*
		 * curcp is the current daemon process context.
		 * userp is the current user process context.
		 */
		curcp = mycp;

		/*
		 * Take daemon off of free queue
		 */
		if (aiop->aioprocflags & AIOP_FREE) {
			TAILQ_REMOVE(&aio_freeproc, aiop, list);
			TAILQ_INSERT_TAIL(&aio_activeproc, aiop, list);
			aiop->aioprocflags &= ~AIOP_FREE;
		}
		aiop->aioprocflags &= ~AIOP_SCHED;

		/*
		 * Check for jobs
		 */
		while ( aiocbe = aio_selectjob(aiop)) {
			struct proc *userp;
			struct aiocb *cb;
			struct kaioinfo *ki;
			struct aio_liojob *lj;

			cb = &aiocbe->uaiocb;
			userp = aiocbe->userproc;

			aiocbe->jobstate = JOBST_JOBRUNNING;

			/*
			 * Connect to process address space for user program
			 */
			if (userp != curcp) {
				struct vmspace *tmpvm;
				/*
				 * Save the current address space that we are connected to.
				 */
				tmpvm = mycp->p_vmspace;
				/*
				 * Point to the new user address space, and refer to it.
				 */
				mycp->p_vmspace = userp->p_vmspace;
				mycp->p_vmspace->vm_refcnt++;
				/*
				 * Activate the new mapping.
				 */
				pmap_activate(mycp);
				/*
				 * If the old address space wasn't the daemons own address
				 * space, then we need to remove the daemon's reference from
				 * the other process that it was acting on behalf of.
				 */
				if (tmpvm != myvm) {
					vmspace_free(tmpvm);
				}
				/*
				 * Disassociate from previous clients file descriptors, and
				 * associate to the new clients descriptors.  Note that
				 * the daemon doesn't need to worry about it's orginal
				 * descriptors, because they were originally freed.
				 */
				if (mycp->p_fd)
					fdfree(mycp);
				mycp->p_fd = fdshare(userp);
				curcp = userp;
			}

			ki = userp->p_aioinfo;
			lj = aiocbe->lio;

			/*
			 * Account for currently active jobs
			 */
			ki->kaio_active_count++;

			/*
			 * Do the I/O function
			 */
			aiocbe->jobaioproc = aiop;
			aio_process(aiocbe);

			/*
			 * decrement the active job count
			 */
			ki->kaio_active_count--;

			/*
			 * increment the completion count for wakeup/signal comparisons
			 */
			aiocbe->jobflags |= AIOCBLIST_DONE;
			ki->kaio_queue_finished_count++;
			if (lj) {
				lj->lioj_queue_finished_count++;
			}
			if ((ki->kaio_flags & KAIO_WAKEUP) ||
				(ki->kaio_flags & KAIO_RUNDOWN) &&
				(ki->kaio_active_count == 0)) {
				ki->kaio_flags &= ~KAIO_WAKEUP;
				wakeup(userp);
			}

			s = splbio();
			if (lj && (lj->lioj_flags & (LIOJ_SIGNAL|LIOJ_SIGNAL_POSTED)) ==
				LIOJ_SIGNAL) {
				if ((lj->lioj_queue_finished_count == lj->lioj_queue_count) &&
					(lj->lioj_buffer_finished_count == lj->lioj_buffer_count)) {
						psignal(userp, lj->lioj_signal.sigev_signo);
						lj->lioj_flags |= LIOJ_SIGNAL_POSTED;
				}
			}
			splx(s);

			aiocbe->jobstate = JOBST_JOBFINISHED;

			/*
			 * If the I/O request should be automatically rundown, do the
			 * needed cleanup.  Otherwise, place the queue entry for
			 * the just finished I/O request into the done queue for the
			 * associated client.
			 */
			if (aiocbe->jobflags & AIOCBLIST_ASYNCFREE) {
				aiocbe->jobflags &= ~AIOCBLIST_ASYNCFREE;
				TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
			} else {
				TAILQ_REMOVE(&ki->kaio_jobqueue,
					aiocbe, plist);
				TAILQ_INSERT_TAIL(&ki->kaio_jobdone,
					aiocbe, plist);
			}

			if (aiocbe->jobflags & AIOCBLIST_RUNDOWN) {
				wakeup(aiocbe);
				aiocbe->jobflags &= ~AIOCBLIST_RUNDOWN;
			}

			if (cb->aio_sigevent.sigev_notify == SIGEV_SIGNAL) {
				psignal(userp, cb->aio_sigevent.sigev_signo);
			}
		}

		/*
		 * Disconnect from user address space
		 */
		if (curcp != mycp) {
			struct vmspace *tmpvm;
			/*
			 * Get the user address space to disconnect from.
			 */
			tmpvm = mycp->p_vmspace;
			/*
			 * Get original address space for daemon.
			 */
			mycp->p_vmspace = myvm;
			/*
			 * Activate the daemon's address space.
			 */
			pmap_activate(mycp);
#if defined(DIAGNOSTIC)
			if (tmpvm == myvm)
				printf("AIOD: vmspace problem -- %d\n", mycp->p_pid);
#endif
			/*
			 * remove our vmspace reference.
			 */
			vmspace_free(tmpvm);
			/*
			 * disassociate from the user process's file descriptors.
			 */
			if (mycp->p_fd)
				fdfree(mycp);
			mycp->p_fd = NULL;
			curcp = mycp;
		}

		/*
		 * If we are the first to be put onto the free queue, wakeup
		 * anyone waiting for a daemon.
		 */
		TAILQ_REMOVE(&aio_activeproc, aiop, list);
		if (TAILQ_EMPTY(&aio_freeproc))
			wakeup(&aio_freeproc);
		TAILQ_INSERT_HEAD(&aio_freeproc, aiop, list);
		aiop->aioprocflags |= AIOP_FREE;

		/*
		 * If daemon is inactive for a long time, allow it to exit, thereby
		 * freeing resources.
		 */
		if (((aiop->aioprocflags & AIOP_SCHED) == 0) &&
			tsleep(mycp, PRIBIO, "aiordy", aiod_lifetime)) {
			if ((TAILQ_FIRST(&aio_jobs) == NULL) &&
				(TAILQ_FIRST(&aiop->jobtorun) == NULL)) {
				if ((aiop->aioprocflags & AIOP_FREE) &&
					(num_aio_procs > target_aio_procs)) {
					TAILQ_REMOVE(&aio_freeproc, aiop, list);
					zfree(aiop_zone, aiop);
					num_aio_procs--;
#if defined(DIAGNOSTIC)
					if (mycp->p_vmspace->vm_refcnt <= 1)
						printf("AIOD: bad vm refcnt for exiting daemon: %d\n",
							mycp->p_vmspace->vm_refcnt);
#endif
					exit1(mycp, 0);
				}
			}
		}
	}
}

/*
 * Create a new AIO daemon.  This is mostly a kernel-thread fork routine.
 * The AIO daemon modifies it's environment itself.
 */
static int
aio_newproc()
{
	int error;
	struct rfork_args rfa;
	struct proc *p, *np;

	rfa.flags = RFPROC | RFCFDG;

	p = curproc;
	if (error = rfork(p, &rfa))
		return error;

	np = pfind(p->p_retval[0]);
	cpu_set_fork_handler(np, aio_daemon, p);

	/*
	 * Wait until daemon is started, but continue on just in case (to
	 * handle error conditions.
	 */
	error = tsleep(np, PZERO, "aiosta", aiod_timeout);
	num_aio_procs++;

	return error;

}

/*
 * Try the high-performance physio method for eligible VCHR devices.  This
 * routine doesn't require the use of any additional threads, and have
 * overhead.
 */
int
aio_qphysio(p, aiocbe)
	struct proc *p;
	struct aiocblist *aiocbe;
{
	int error;
	caddr_t sa;
	struct aiocb *cb;
	struct file *fp;
	struct buf *bp;
	int bflags;
	struct vnode *vp;
	struct kaioinfo *ki;
	struct filedesc *fdp;
	struct aio_liojob *lj;
	int fd;
	int majordev;
	int s;
	int cnt;
	dev_t dev;
	int rw;
	d_strategy_t *fstrategy;
	struct cdevsw *cdev;
	struct bdevsw *bdev;

	cb = &aiocbe->uaiocb;
	fdp = p->p_fd;
	fd = cb->aio_fildes;
	fp = fdp->fd_ofiles[fd];

	if (fp->f_type != DTYPE_VNODE) {
		return -1;
	}

	vp = (struct vnode *)fp->f_data;
	if (vp->v_type != VCHR || ((cb->aio_nbytes & (DEV_BSIZE - 1)) != 0)) {
		return -1;
	}

	if ((cb->aio_nbytes > MAXPHYS) && (num_buf_aio >= max_buf_aio)) {
		return -1;
	}

	if ((vp->v_specinfo == NULL) || (vp->v_flag & VISTTY)) {
		return -1;
	}

	majordev = major(vp->v_rdev);
	if (majordev == NODEV) {
		return -1;
	}

	cdev = cdevsw[major(vp->v_rdev)];
	if (cdev == NULL) {
		return -1;
	}
	bdev = cdev->d_bdev;
	if (bdev == NULL) {
		return -1;
	}

	ki = p->p_aioinfo;
	if (ki->kaio_buffer_count >= ki->kaio_ballowed_count) {
		return -1;
	}

	cnt = cb->aio_nbytes;
	if (cnt > MAXPHYS) {
		return -1;
	}

	dev = makedev(bdev->d_maj, minor(vp->v_rdev));

	/*
	 * Physical I/O is charged directly to the process, so we don't have
	 * to fake it.
	 */
	aiocbe->inputcharge = 0;
	aiocbe->outputcharge = 0;

	ki->kaio_buffer_count++;

	lj = aiocbe->lio;
	if (lj) {
		lj->lioj_buffer_count++;
	}

	/* create and build a buffer header for a transfer */
	bp = (struct buf *)getpbuf();

	/*
	 * get a copy of the kva from the physical buffer
	 */
	bp->b_proc = p;
	bp->b_dev = dev;
	error = bp->b_error = 0;

	if (cb->aio_lio_opcode == LIO_WRITE) {
		rw = 0;
		bflags = B_WRITE;
	} else {
		rw = 1;
		bflags = B_READ;
	}
	
	bp->b_bcount = cb->aio_nbytes;
	bp->b_bufsize = cb->aio_nbytes;
	bp->b_flags = B_BUSY | B_PHYS | B_CALL | bflags;
	bp->b_iodone = aio_physwakeup;
	bp->b_saveaddr = bp->b_data;
	bp->b_data = cb->aio_buf;
	bp->b_blkno = btodb(cb->aio_offset);

	if (rw && !useracc(bp->b_data, bp->b_bufsize, B_WRITE)) {
		error = EFAULT;
		goto doerror;
	}
	if (!rw && !useracc(bp->b_data, bp->b_bufsize, B_READ)) {
		error = EFAULT;
		goto doerror;
	}

	/* bring buffer into kernel space */
	vmapbuf(bp);

	s = splbio();
	aiocbe->bp = bp;
	bp->b_spc = (void *)aiocbe;
	TAILQ_INSERT_TAIL(&aio_bufjobs, aiocbe, list);
	TAILQ_INSERT_TAIL(&ki->kaio_bufqueue, aiocbe, plist);
	aiocbe->jobstate = JOBST_JOBQBUF;
	cb->_aiocb_private.status = cb->aio_nbytes;
	num_buf_aio++;
	fstrategy = bdev->d_strategy;
	bp->b_error = 0;

	splx(s);
	/* perform transfer */
	(*fstrategy)(bp);

	s = splbio();
	/*
	 * If we had an error invoking the request, or an error in processing
	 * the request before we have returned, we process it as an error
	 * in transfer.  Note that such an I/O error is not indicated immediately,
	 * but is returned using the aio_error mechanism.  In this case, aio_suspend
	 * will return immediately.
	 */
	if (bp->b_error || (bp->b_flags & B_ERROR)) {
		struct aiocb *job = aiocbe->uuaiocb;

		aiocbe->uaiocb._aiocb_private.status = 0;
		suword(&job->_aiocb_private.status, 0);
		aiocbe->uaiocb._aiocb_private.error = bp->b_error;
		suword(&job->_aiocb_private.error, bp->b_error);

		ki->kaio_buffer_finished_count++;

		if (aiocbe->jobstate != JOBST_JOBBFINISHED) {
			aiocbe->jobstate = JOBST_JOBBFINISHED;
			aiocbe->jobflags |= AIOCBLIST_DONE;
			TAILQ_REMOVE(&aio_bufjobs, aiocbe, list);
			TAILQ_REMOVE(&ki->kaio_bufqueue, aiocbe, plist);
			TAILQ_INSERT_TAIL(&ki->kaio_bufdone, aiocbe, plist);
		}
	}
	splx(s);
	return 0;

doerror:
	ki->kaio_buffer_count--;
	if (lj) {
		lj->lioj_buffer_count--;
	}
	aiocbe->bp = NULL;
	relpbuf(bp);
	return error;
}

/*
 * This waits/tests physio completion.
 */
int
aio_fphysio(p, iocb, flgwait)
	struct proc *p;
	struct aiocblist *iocb;
	int flgwait;
{
	int s;
	struct buf *bp;
	int error;

	bp = iocb->bp;

	s = splbio();
	if (flgwait == 0) {
		if ((bp->b_flags & B_DONE) == 0) {
			splx(s);
			return EINPROGRESS;
		}
	}

	while ((bp->b_flags & B_DONE) == 0) {
		if (tsleep((caddr_t)bp, PRIBIO, "physstr", aiod_timeout)) {
			if ((bp->b_flags & B_DONE) == 0) {
				splx(s);
				return EINPROGRESS;
			} else {
				break;
			}
		}
	}

	/* release mapping into kernel space */
	vunmapbuf(bp);
	iocb->bp = 0;

	error = 0;
	/*
	 * check for an error
	 */
	if (bp->b_flags & B_ERROR) {
		error = bp->b_error;
	}

	relpbuf(bp);
	return (error);
}

/*
 * Queue a new AIO request.  Choosing either the threaded or direct physio
 * VCHR technique is done in this code.
 */
static int
_aio_aqueue(struct proc *p, struct aiocb *job, struct aio_liojob *lj, int type)
{
	struct filedesc *fdp;
	struct file *fp;
	unsigned int fd;

	int error;
	int opcode;
	struct aiocblist *aiocbe;
	struct aioproclist *aiop;
	struct kaioinfo *ki;

	if (aiocbe = TAILQ_FIRST(&aio_freejobs)) {
		TAILQ_REMOVE(&aio_freejobs, aiocbe, list);
	} else {
		aiocbe = zalloc (aiocb_zone);
	}

	aiocbe->inputcharge = 0;
	aiocbe->outputcharge = 0;

	suword(&job->_aiocb_private.status, -1);
	suword(&job->_aiocb_private.error, 0);
	suword(&job->_aiocb_private.kernelinfo, -1);

	error = copyin((caddr_t)job,
		(caddr_t) &aiocbe->uaiocb, sizeof aiocbe->uaiocb);
	if (error) {
		suword(&job->_aiocb_private.error, error);

		TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
		return error;
	}

	/*
	 * Save userspace address of the job info
	 */
	aiocbe->uuaiocb = job;

	/*
	 * Get the opcode
	 */
	if (type != LIO_NOP) {
		aiocbe->uaiocb.aio_lio_opcode = type;
	}
	opcode = aiocbe->uaiocb.aio_lio_opcode;

	/*
	 * Get the fd info for process
	 */
	fdp = p->p_fd;

	/*
	 * Range check file descriptor
	 */
	fd = aiocbe->uaiocb.aio_fildes;
	if (fd >= fdp->fd_nfiles) {
		TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
		if (type == 0) {
			suword(&job->_aiocb_private.error, EBADF);
		}
		return EBADF;
	}

	fp = fdp->fd_ofiles[fd];
	if ((fp == NULL) ||
		((opcode == LIO_WRITE) && ((fp->f_flag & FWRITE) == 0))) {
		TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
		if (type == 0) {
			suword(&job->_aiocb_private.error, EBADF);
		}
		return EBADF;
	}

	if (aiocbe->uaiocb.aio_offset == -1LL) {
		TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
		if (type == 0) {
			suword(&job->_aiocb_private.error, EINVAL);
		}
		return EINVAL;
	}

	error = suword(&job->_aiocb_private.kernelinfo, jobrefid);
	if (error) {
		TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
		if (type == 0) {
			suword(&job->_aiocb_private.error, EINVAL);
		}
		return error;
	}

	aiocbe->uaiocb._aiocb_private.kernelinfo = (void *)jobrefid;
	jobrefid++;
	if (jobrefid > INT_MAX)
		jobrefid = 1;
	
	if (opcode == LIO_NOP) {
		TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
		if (type == 0) {
			suword(&job->_aiocb_private.error, 0);
			suword(&job->_aiocb_private.status, 0);
			suword(&job->_aiocb_private.kernelinfo, 0);
		}
		return 0;
	}

	if ((opcode != LIO_READ) && (opcode != LIO_WRITE)) {
		TAILQ_INSERT_HEAD(&aio_freejobs, aiocbe, list);
		if (type == 0) {
			suword(&job->_aiocb_private.status, 0);
			suword(&job->_aiocb_private.error, EINVAL);
		}
		return EINVAL;
	}

	suword(&job->_aiocb_private.error, EINPROGRESS);
	aiocbe->uaiocb._aiocb_private.error = EINPROGRESS;
	aiocbe->userproc = p;
	aiocbe->jobflags = 0;
	aiocbe->lio = lj;
	ki = p->p_aioinfo;

	if ((error = aio_qphysio(p, aiocbe)) == 0) {
		return 0;
	} else if (error > 0) {
		suword(&job->_aiocb_private.status, 0);
		aiocbe->uaiocb._aiocb_private.error = error;
		suword(&job->_aiocb_private.error, error);
		return error;
	}

	/*
	 * No buffer for daemon I/O
	 */
	aiocbe->bp = NULL;

	ki->kaio_queue_count++;
	if (lj) {
		lj->lioj_queue_count++;
	}
	TAILQ_INSERT_TAIL(&ki->kaio_jobqueue, aiocbe, plist);
	TAILQ_INSERT_TAIL(&aio_jobs, aiocbe, list);
	aiocbe->jobstate = JOBST_JOBQGLOBAL;

	num_queue_count++;
	error = 0;

	/*
	 * If we don't have a free AIO process, and we are below our
	 * quota, then start one.  Otherwise, depend on the subsequent
	 * I/O completions to pick-up this job.  If we don't sucessfully
	 * create the new process (thread) due to resource issues, we
	 * return an error for now (EAGAIN), which is likely not the
	 * correct thing to do.
	 */
retryproc:
	if (aiop = TAILQ_FIRST(&aio_freeproc)) {
		TAILQ_REMOVE(&aio_freeproc, aiop, list);
		TAILQ_INSERT_TAIL(&aio_activeproc, aiop, list);
		aiop->aioprocflags &= ~AIOP_FREE;
		wakeup(aiop->aioproc);
	} else if (((num_aio_resv_start + num_aio_procs) < max_aio_procs) &&
			((ki->kaio_active_count + num_aio_resv_start) <
				ki->kaio_maxactive_count)) {
		num_aio_resv_start++;
		if ((error = aio_newproc()) == 0) {
			num_aio_resv_start--;
			p->p_retval[0] = 0;
			goto retryproc;
		}
		num_aio_resv_start--;
	}
	return error;
}

/*
 * This routine queues an AIO request, checking for quotas.
 */
static int
aio_aqueue(struct proc *p, struct aiocb *job, int type)
{
	struct kaioinfo *ki;

	if (p->p_aioinfo == NULL) {
		aio_init_aioinfo(p);
	}

	if (num_queue_count >= max_queue_count)
		return EAGAIN;

	ki = p->p_aioinfo;
	if (ki->kaio_queue_count >= ki->kaio_qallowed_count)
		return EAGAIN;

	return _aio_aqueue(p, job, NULL, type);
}

/*
 * Support the aio_return system call, as a side-effect, kernel
 * resources are released.
 */
int
aio_return(struct proc *p, struct aio_return_args *uap)
{
	int s;
	int jobref, status;
	struct aiocblist *cb, *ncb;
	struct aiocb *ujob;
	struct kaioinfo *ki;
	struct proc *userp;

	ki = p->p_aioinfo;
	if (ki == NULL) {
		return EINVAL;
	}

	ujob = uap->aiocbp;

	jobref = fuword(&ujob->_aiocb_private.kernelinfo);
	if (jobref == -1 || jobref == 0)
		return EINVAL;

	for (cb = TAILQ_FIRST(&ki->kaio_jobdone);
		cb;
		cb = TAILQ_NEXT(cb, plist)) {
		if (((int) cb->uaiocb._aiocb_private.kernelinfo) == jobref) {
			if (ujob == cb->uuaiocb) {
				p->p_retval[0] = cb->uaiocb._aiocb_private.status;
			} else {
				p->p_retval[0] = EFAULT;
			}
			if (cb->uaiocb.aio_lio_opcode == LIO_WRITE) {
				curproc->p_stats->p_ru.ru_oublock += cb->outputcharge;
				cb->outputcharge = 0;
			} else if (cb->uaiocb.aio_lio_opcode == LIO_READ) {
				curproc->p_stats->p_ru.ru_inblock += cb->inputcharge;
				cb->inputcharge = 0;
			}
			aio_free_entry(cb);
			return 0;
		}
	}

	s = splbio();
	for (cb = TAILQ_FIRST(&ki->kaio_bufdone);
		cb;
		cb = ncb) {
		ncb = TAILQ_NEXT(cb, plist);
		if (((int) cb->uaiocb._aiocb_private.kernelinfo) == jobref) {
			splx(s);
			if (ujob == cb->uuaiocb) {
				p->p_retval[0] = cb->uaiocb._aiocb_private.status;
			} else {
				p->p_retval[0] = EFAULT;
			}
			aio_free_entry(cb);
			return 0;
		}
	}
	splx(s);

	return (EINVAL);
}

/*
 * Allow a process to wakeup when any of the I/O requests are
 * completed.
 */
int
aio_suspend(struct proc *p, struct aio_suspend_args *uap)
{
	struct timeval atv;
	struct timespec ts;
	struct aiocb *const *cbptr, *cbp;
	struct kaioinfo *ki;
	struct aiocblist *cb;
	int i;
	int njoblist;
	int error, s, timo;
	int *ijoblist;
	struct aiocb **ujoblist;
	
	if (uap->nent >= AIO_LISTIO_MAX)
		return EINVAL;

	timo = 0;
	if (uap->timeout) {
		/*
		 * Get timespec struct
		 */
		if (error = copyin((caddr_t) uap->timeout, (caddr_t) &ts, sizeof ts)) {
			return error;
		}

		if (ts.tv_nsec < 0 || ts.tv_nsec >= 1000000000)
			return (EINVAL);

		TIMESPEC_TO_TIMEVAL(&atv, &ts)
		if (itimerfix(&atv))
			return (EINVAL);
		/*
		 * XXX this is not as careful as settimeofday() about minimising
		 * interrupt latency.  The hzto() interface is inconvenient as usual.
		 */
		s = splclock();
		timevaladd(&atv, &time);
		timo = hzto(&atv);
		splx(s);
		if (timo == 0)
			timo = 1;
	}

	ki = p->p_aioinfo;
	if (ki == NULL)
		return EAGAIN;

	njoblist = 0;
	ijoblist = zalloc(aiol_zone);
	ujoblist = zalloc(aiol_zone);
	cbptr = uap->aiocbp;

	for(i = 0; i < uap->nent; i++) {
		cbp = (struct aiocb *) fuword((caddr_t) &cbptr[i]);
		if (cbp == 0)
			continue;
		ujoblist[njoblist] = cbp;
		ijoblist[njoblist] = fuword(&cbp->_aiocb_private.kernelinfo);
		njoblist++;
	}
	if (njoblist == 0) {
		zfree(aiol_zone, ijoblist);
		zfree(aiol_zone, ujoblist);
		return 0;
	}

	error = 0;
	while (1) {
		for (cb = TAILQ_FIRST(&ki->kaio_jobdone);
			cb; cb = TAILQ_NEXT(cb, plist)) {
			for(i = 0; i < njoblist; i++) {
				if (((int) cb->uaiocb._aiocb_private.kernelinfo) ==
					ijoblist[i]) {
					if (ujoblist[i] != cb->uuaiocb)
						error = EINVAL;
					zfree(aiol_zone, ijoblist);
					zfree(aiol_zone, ujoblist);
					return error;
				}
			}
		}

		s = splbio();
		for (cb = TAILQ_FIRST(&ki->kaio_bufdone);
			cb; cb = TAILQ_NEXT(cb, plist)) {
			for(i = 0; i < njoblist; i++) {
				if (((int) cb->uaiocb._aiocb_private.kernelinfo) ==
					ijoblist[i]) {
					splx(s);
					if (ujoblist[i] != cb->uuaiocb)
						error = EINVAL;
					zfree(aiol_zone, ijoblist);
					zfree(aiol_zone, ujoblist);
					return error;
				}
			}
		}

		ki->kaio_flags |= KAIO_WAKEUP;
		error = tsleep(p, PRIBIO|PCATCH, "aiospn", timo);
		splx(s);

		if (error == EINTR) {
			zfree(aiol_zone, ijoblist);
			zfree(aiol_zone, ujoblist);
			return EINTR;
		} else if (error == EWOULDBLOCK) {
			zfree(aiol_zone, ijoblist);
			zfree(aiol_zone, ujoblist);
			return EAGAIN;
		}
	}

/* NOTREACHED */
	return EINVAL;
}

/*
 * aio_cancel at the kernel level is a NOOP right now.  It
 * might be possible to support it partially in user mode, or
 * in kernel mode later on.
 */
int
aio_cancel(struct proc *p, struct aio_cancel_args *uap)
{
	return AIO_NOTCANCELLED;
}

/*
 * aio_error is implemented in the kernel level for compatibility
 * purposes only.  For a user mode async implementation, it would be
 * best to do it in a userland subroutine.
 */
int
aio_error(struct proc *p, struct aio_error_args *uap)
{
	int s;
	struct aiocblist *cb;
	struct kaioinfo *ki;
	int jobref;
	int error, status;

	ki = p->p_aioinfo;
	if (ki == NULL)
		return EINVAL;

	jobref = fuword(&uap->aiocbp->_aiocb_private.kernelinfo);
	if ((jobref == -1) || (jobref == 0))
		return EINVAL;

	for (cb = TAILQ_FIRST(&ki->kaio_jobdone);
		cb;
		cb = TAILQ_NEXT(cb, plist)) {

		if (((int) cb->uaiocb._aiocb_private.kernelinfo) == jobref) {
			p->p_retval[0] = cb->uaiocb._aiocb_private.error;
			return 0;
		}
	}

	for (cb = TAILQ_FIRST(&ki->kaio_jobqueue);
		cb;
		cb = TAILQ_NEXT(cb, plist)) {

		if (((int) cb->uaiocb._aiocb_private.kernelinfo) == jobref) {
			p->p_retval[0] = EINPROGRESS;
			return 0;
		}
	}

	s = splbio();
	for (cb = TAILQ_FIRST(&ki->kaio_bufdone);
		cb;
		cb = TAILQ_NEXT(cb, plist)) {
		if (((int) cb->uaiocb._aiocb_private.kernelinfo) == jobref) {
			p->p_retval[0] = cb->uaiocb._aiocb_private.error;
			splx(s);
			return 0;
		}
	}

	for (cb = TAILQ_FIRST(&ki->kaio_bufqueue);
		cb;
		cb = TAILQ_NEXT(cb, plist)) {
		if (((int) cb->uaiocb._aiocb_private.kernelinfo) == jobref) {
			p->p_retval[0] = EINPROGRESS;
			splx(s);
			return 0;
		}
	}
	splx(s);


	/*
	 * Hack for lio
	 */
/*
	status = fuword(&uap->aiocbp->_aiocb_private.status);
	if (status == -1) {
		return fuword(&uap->aiocbp->_aiocb_private.error);
	}
*/
	return EINVAL;
}

int
aio_read(struct proc *p, struct aio_read_args *uap)
{
	struct filedesc *fdp;
	struct file *fp;
	struct uio auio;
	struct iovec aiov;
	unsigned int fd;
	int cnt;
	struct aiocb iocb;
	int error, pmodes;

	pmodes = fuword(&uap->aiocbp->_aiocb_private.privatemodes);
	if ((pmodes & AIO_PMODE_SYNC) == 0) {
		return aio_aqueue(p, (struct aiocb *) uap->aiocbp, LIO_READ);
	}

	/*
	 * Get control block
	 */
	if (error = copyin((caddr_t) uap->aiocbp, (caddr_t) &iocb, sizeof iocb))
		return error;

	/*
	 * Get the fd info for process
	 */
	fdp = p->p_fd;

	/*
	 * Range check file descriptor
	 */
	fd = iocb.aio_fildes;
	if (fd >= fdp->fd_nfiles)
		return EBADF;
	fp = fdp->fd_ofiles[fd];
	if ((fp == NULL) || ((fp->f_flag & FREAD) == 0))
		return EBADF;
	if (iocb.aio_offset == -1LL)
		return EINVAL;

	auio.uio_resid = iocb.aio_nbytes;
	if (auio.uio_resid < 0)
		return (EINVAL);

	/*
	 * Process sync simply -- queue async request.
	 */
	if ((iocb._aiocb_private.privatemodes & AIO_PMODE_SYNC) == 0) {
		return aio_aqueue(p, (struct aiocb *) uap->aiocbp, LIO_READ);
	}

	aiov.iov_base = iocb.aio_buf;
	aiov.iov_len = iocb.aio_nbytes;

	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_offset = iocb.aio_offset;
	auio.uio_rw = UIO_READ;
	auio.uio_segflg = UIO_USERSPACE;
	auio.uio_procp = p;

	cnt = iocb.aio_nbytes;
	error = (*fp->f_ops->fo_read)(fp, &auio, fp->f_cred);
	if (error &&
		(auio.uio_resid != cnt) &&
		(error == ERESTART || error == EINTR || error == EWOULDBLOCK))
			error = 0;
	cnt -= auio.uio_resid;
	p->p_retval[0] = cnt;
	return error;
}

int
aio_write(struct proc *p, struct aio_write_args *uap)
{
	struct filedesc *fdp;
	struct file *fp;
	struct uio auio;
	struct iovec aiov;
	unsigned int fd;
	int cnt;
	struct aiocb iocb;
	int error;
	int pmodes;

	/*
	 * Process sync simply -- queue async request.
	 */
	pmodes = fuword(&uap->aiocbp->_aiocb_private.privatemodes);
	if ((pmodes & AIO_PMODE_SYNC) == 0) {
		return aio_aqueue(p, (struct aiocb *) uap->aiocbp, LIO_WRITE);
	}

	if (error = copyin((caddr_t) uap->aiocbp, (caddr_t) &iocb, sizeof iocb))
		return error;

	/*
	 * Get the fd info for process
	 */
	fdp = p->p_fd;

	/*
	 * Range check file descriptor
	 */
	fd = iocb.aio_fildes;
	if (fd >= fdp->fd_nfiles)
		return EBADF;
	fp = fdp->fd_ofiles[fd];
	if ((fp == NULL) || ((fp->f_flag & FWRITE) == 0))
		return EBADF;
	if (iocb.aio_offset == -1LL)
		return EINVAL;

	aiov.iov_base = iocb.aio_buf;
	aiov.iov_len = iocb.aio_nbytes;
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_offset = iocb.aio_offset;

	auio.uio_resid = iocb.aio_nbytes;
	if (auio.uio_resid < 0)
		return (EINVAL);

	auio.uio_rw = UIO_WRITE;
	auio.uio_segflg = UIO_USERSPACE;
	auio.uio_procp = p;

	cnt = iocb.aio_nbytes;
	error = (*fp->f_ops->fo_write)(fp, &auio, fp->f_cred);
	if (error) {
		if (auio.uio_resid != cnt) {
			if (error == ERESTART || error == EINTR || error == EWOULDBLOCK)
				error = 0;
			if (error == EPIPE)
				psignal(p, SIGPIPE);
		}
	}
	cnt -= auio.uio_resid;
	p->p_retval[0] = cnt;
	return error;
}

int
lio_listio(struct proc *p, struct lio_listio_args *uap)
{
	int nent, nentqueued;
	struct aiocb *iocb, * const *cbptr;
	struct aiocblist *cb;
	struct kaioinfo *ki;
	struct aio_liojob *lj;
	int error, runningcode;
	int nerror;
	int i;
	int s;

	if ((uap->mode != LIO_NOWAIT) && (uap->mode != LIO_WAIT)) {
		return EINVAL;
	}

	nent = uap->nent;
	if (nent > AIO_LISTIO_MAX) {
		return EINVAL;
	}

	if (p->p_aioinfo == NULL) {
		aio_init_aioinfo(p);
	}

	if ((nent + num_queue_count) > max_queue_count) {
		return EAGAIN;
	}

	ki = p->p_aioinfo;
	if ((nent + ki->kaio_queue_count) > ki->kaio_qallowed_count) {
		return EAGAIN;
	}

	lj = zalloc(aiolio_zone);
	if (!lj) {
		return EAGAIN;
	}

	lj->lioj_flags = 0;
	lj->lioj_buffer_count = 0;
	lj->lioj_buffer_finished_count = 0;
	lj->lioj_queue_count = 0;
	lj->lioj_queue_finished_count = 0;
	lj->lioj_ki = ki;
	TAILQ_INSERT_TAIL(&ki->kaio_liojoblist, lj, lioj_list);

	/*
	 * Setup signal
	 */
	if (uap->sig && (uap->mode == LIO_NOWAIT)) {
		error = copyin(uap->sig, &lj->lioj_signal, sizeof lj->lioj_signal);
		if (error)
			return error;
		lj->lioj_flags |= LIOJ_SIGNAL;
		lj->lioj_flags &= ~LIOJ_SIGNAL_POSTED;
	} else {
		lj->lioj_flags &= ~LIOJ_SIGNAL;
	}

/*
 * get pointers to the list of I/O requests
 */

	nerror = 0;
	nentqueued = 0;
	cbptr = uap->acb_list;
	for(i = 0; i < uap->nent; i++) {
		iocb = (struct aiocb *) fuword((caddr_t) &cbptr[i]);
		if (((int) iocb != -1) && ((int) iocb != NULL)) {
			error = _aio_aqueue(p, iocb, lj, 0);
			if (error == 0) {
				nentqueued++;
			} else {
				nerror++;
			}
		}
	}

	/*
	 * If we haven't queued any, then just return error
	 */
	if (nentqueued == 0) {
		return 0;
	}

	/*
	 * Calculate the appropriate error return
	 */
	runningcode = 0;
	if (nerror)
		runningcode = EIO;

	if (uap->mode == LIO_WAIT) {
		while (1) {
			int found;
			found = 0;
			for(i = 0; i < uap->nent; i++) {
				int jobref, command;

				/*
				 * Fetch address of the control buf pointer in user space
				 */
				iocb = (struct aiocb *) fuword((caddr_t) &cbptr[i]);
				if (((int) iocb == -1) || ((int) iocb == 0))
					continue;

				/*
				 * Fetch the associated command from user space
				 */
				command = fuword(&iocb->aio_lio_opcode);
				if (command == LIO_NOP) {
					found++;
					continue;
				}

				jobref = fuword(&iocb->_aiocb_private.kernelinfo);

				for (cb = TAILQ_FIRST(&ki->kaio_jobdone);
					cb;
					cb = TAILQ_NEXT(cb, plist)) {
					if (((int) cb->uaiocb._aiocb_private.kernelinfo) ==
						jobref) {
						if (cb->uaiocb.aio_lio_opcode == LIO_WRITE) {
							curproc->p_stats->p_ru.ru_oublock +=
								cb->outputcharge;
							cb->outputcharge = 0;
						} else if (cb->uaiocb.aio_lio_opcode == LIO_READ) {
							curproc->p_stats->p_ru.ru_inblock +=
								cb->inputcharge;
							cb->inputcharge = 0;
						}
						found++;
						break;
					}
				}

				s = splbio();
				for (cb = TAILQ_FIRST(&ki->kaio_bufdone);
					cb;
					cb = TAILQ_NEXT(cb, plist)) {
					if (((int) cb->uaiocb._aiocb_private.kernelinfo) ==
						jobref) {
						found++;
						break;
					}
				}
				splx(s);
				
			}

			/*
			 * If all I/Os have been disposed of, then we can return
			 */
			if (found == nentqueued) {
				return runningcode;
			}
			
			ki->kaio_flags |= KAIO_WAKEUP;
			error = tsleep(p, PRIBIO|PCATCH, "aiospn", 0);

			if (error == EINTR) {
				return EINTR;
			} else if (error == EWOULDBLOCK) {
				return EAGAIN;
			}

		}
	}

	return runningcode;
}

/*
 * This is a wierd hack so that we can post a signal.  It is safe
 * to do so from a timeout routine, but *not* from an interrupt routine.
 */
static void
process_signal(void *ljarg)
{
	struct aio_liojob *lj = ljarg;
	if (lj->lioj_signal.sigev_notify == SIGEV_SIGNAL) {
		if (lj->lioj_queue_count == lj->lioj_queue_finished_count) {
			psignal(lj->lioj_ki->kaio_p, lj->lioj_signal.sigev_signo);
			lj->lioj_flags |= LIOJ_SIGNAL_POSTED;
		}
	}
}

/*
 * Interrupt handler for physio, performs the necessary process wakeups,
 * and signals.
 */
static void
aio_physwakeup(bp)
	struct buf *bp;
{
	struct aiocblist *aiocbe;
	struct proc *p;
	struct kaioinfo *ki;
	struct aio_liojob *lj;
	int s;
	s = splbio();

	wakeup((caddr_t) bp);
	bp->b_flags &= ~B_CALL;
	bp->b_flags |= B_DONE;

	aiocbe = (struct aiocblist *)bp->b_spc;
	if (aiocbe) {
		p = bp->b_proc;

		aiocbe->jobstate = JOBST_JOBBFINISHED;
		aiocbe->uaiocb._aiocb_private.status -= bp->b_resid;
		aiocbe->uaiocb._aiocb_private.error = 0;
		aiocbe->jobflags |= AIOCBLIST_DONE;

		if (bp->b_flags & B_ERROR) {
			aiocbe->uaiocb._aiocb_private.error = bp->b_error;
		}

		lj = aiocbe->lio;
		if (lj) {
			lj->lioj_buffer_finished_count++;
			/*
			 * wakeup/signal if all of the interrupt jobs are done
			 */
			if (lj->lioj_buffer_finished_count == lj->lioj_buffer_count) {
				/*
				 * post a signal if it is called for
				 */
				if ((lj->lioj_flags & (LIOJ_SIGNAL|LIOJ_SIGNAL_POSTED)) ==
					LIOJ_SIGNAL) {
					lj->lioj_flags |= LIOJ_SIGNAL_POSTED;
					timeout(process_signal, lj, 0);
				}
			}
		}

		ki = p->p_aioinfo;
		if (ki) {
			ki->kaio_buffer_finished_count++;
			TAILQ_REMOVE(&aio_bufjobs, aiocbe, list);
			TAILQ_REMOVE(&ki->kaio_bufqueue, aiocbe, plist);
			TAILQ_INSERT_TAIL(&ki->kaio_bufdone, aiocbe, plist);
			/*
			 * and do the wakeup
			 */
			if (ki->kaio_flags & (KAIO_RUNDOWN|KAIO_WAKEUP)) {
				ki->kaio_flags &= ~KAIO_WAKEUP;
				wakeup(p);
			}
		}
	}
	splx(s);
}