[apple/xnu.git] / bsd / kern / kern_acct.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*-
 * Copyright (c) 1982, 1986, 1989, 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. 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.
 *
 *	@(#)kern_acct.c	8.1 (Berkeley) 6/14/93
 */
/* HISTORY
 * 08-May-95  Mac Gillon (mgillon) at NeXT
 *	Purged old history
 *  	New version based on 4.4
 */


#include <sys/param.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/syslog.h>
#include <sys/kernel.h>
#include <sys/namei.h>
#include <sys/errno.h>
#include <sys/acct.h>
#include <sys/resourcevar.h>
#include <sys/ioctl.h>
#include <sys/tty.h>

/*
 * The routines implemented in this file are described in:
 *      Leffler, et al.: The Design and Implementation of the 4.3BSD
 *	    UNIX Operating System (Addison Welley, 1989)
 * on pages 62-63.
 *
 * Arguably, to simplify accounting operations, this mechanism should
 * be replaced by one in which an accounting log file (similar to /dev/klog)
 * is read by a user process, etc.  However, that has its own problems.
 */

/*
 * Internal accounting functions.
 * The former's operation is described in Leffler, et al., and the latter
 * was provided by UCB with the 4.4BSD-Lite release
 */
comp_t	encode_comp_t __P((u_long, u_long));
void	acctwatch __P((void *));
void	acctwatch_funnel __P((void *));

/*
 * Accounting vnode pointer, and saved vnode pointer.
 */
struct	vnode *acctp;
struct	vnode *savacctp;

/*
 * Values associated with enabling and disabling accounting
 */
int	acctsuspend = 2;	/* stop accounting when < 2% free space left */
int	acctresume = 4;		/* resume when free space risen to > 4% */
int	acctchkfreq = 15;	/* frequency (in seconds) to check space */

/*
 * Accounting system call.  Written based on the specification and
 * previous implementation done by Mark Tinguely.
 */
struct acct_args {
	char	*path;
};
acct(p, uap, retval)
	struct proc *p;
	struct acct_args *uap;
	int *retval;
{
	struct nameidata nd;
	int error;

	/* Make sure that the caller is root. */
	if (error = suser(p->p_ucred, &p->p_acflag))
		return (error);

	/*
	 * If accounting is to be started to a file, open that file for
	 * writing and make sure it's a 'normal'.
	 */
	if (uap->path != NULL) {
		NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, p);
		if (error = vn_open(&nd, FWRITE, 0))
			return (error);
		VOP_UNLOCK(nd.ni_vp, 0, p);
		if (nd.ni_vp->v_type != VREG) {
			vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
			return (EACCES);
		}
	}

	/*
	 * If accounting was previously enabled, kill the old space-watcher,
	 * close the file, and (if no new file was specified, leave).
	 */
	if (acctp != NULLVP || savacctp != NULLVP) {
		untimeout(acctwatch_funnel, NULL);
		error = vn_close((acctp != NULLVP ? acctp : savacctp), FWRITE,
		    p->p_ucred, p);
		acctp = savacctp = NULLVP;
	}
	if (uap->path == NULL)
		return (error);

	/*
	 * Save the new accounting file vnode, and schedule the new
	 * free space watcher.
	 */
	acctp = nd.ni_vp;
	acctwatch(NULL);
	return (error);
}

/*
 * Write out process accounting information, on process exit.
 * Data to be written out is specified in Leffler, et al.
 * and are enumerated below.  (They're also noted in the system
 * "acct.h" header file.)
 */
acct_process(p)
	struct proc *p;
{
	struct acct acct;
	struct rusage *r;
	struct timeval ut, st, tmp;
	int s, t;
	struct vnode *vp;

	/* If accounting isn't enabled, don't bother */
	vp = acctp;
	if (vp == NULLVP)
		return (0);

	/*
	 * Get process accounting information.
	 */

	/* (1) The name of the command that ran */
	bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);

	/* (2) The amount of user and system time that was used */
	calcru(p, &ut, &st, NULL);
	acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
	acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);

	/* (3) The elapsed time the commmand ran (and its starting time) */
	acct.ac_btime = p->p_stats->p_start.tv_sec;
	s = splclock();
	tmp = time;
	splx(s);
	timevalsub(&tmp, &p->p_stats->p_start);
	acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);

	/* (4) The average amount of memory used */
	r = &p->p_stats->p_ru;
	tmp = ut;
	timevaladd(&tmp, &st);
	t = tmp.tv_sec * hz + tmp.tv_usec / tick;
	if (t)
		acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
	else
		acct.ac_mem = 0;

	/* (5) The number of disk I/O operations done */
	acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);

	/* (6) The UID and GID of the process */
	acct.ac_uid = p->p_cred->p_ruid;
	acct.ac_gid = p->p_cred->p_rgid;

	/* (7) The terminal from which the process was started */
	if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
		acct.ac_tty = p->p_pgrp->pg_session->s_ttyp->t_dev;
	else
		acct.ac_tty = NODEV;

	/* (8) The boolean flags that tell how the process terminated, etc. */
	acct.ac_flag = p->p_acflag;

	/*
	 * Now, just write the accounting information to the file.
	 */
	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
	return (vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
	    (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, p->p_ucred,
	    (int *)0, p));
}

/*
 * Encode_comp_t converts from ticks in seconds and microseconds
 * to ticks in 1/AHZ seconds.  The encoding is described in
 * Leffler, et al., on page 63.
 */

#define	MANTSIZE	13			/* 13 bit mantissa. */
#define	EXPSIZE		3			/* Base 8 (3 bit) exponent. */
#define	MAXFRACT	((1 << MANTSIZE) - 1)	/* Maximum fractional value. */

comp_t
encode_comp_t(s, us)
	u_long s, us;
{
	int exp, rnd;

	exp = 0;
	rnd = 0;
	s *= AHZ;
	s += us / (1000000 / AHZ);	/* Maximize precision. */

	while (s > MAXFRACT) {
	rnd = s & (1 << (EXPSIZE - 1));	/* Round up? */
		s >>= EXPSIZE;		/* Base 8 exponent == 3 bit shift. */
		exp++;
	}

	/* If we need to round up, do it (and handle overflow correctly). */
	if (rnd && (++s > MAXFRACT)) {
		s >>= EXPSIZE;
		exp++;
	}

	/* Clean it up and polish it off. */
	exp <<= MANTSIZE;		/* Shift the exponent into place */
	exp += s;			/* and add on the mantissa. */
	return (exp);
}

void
acctwatch_funnel(a)
	void *a;
{
        thread_funnel_set(kernel_flock, TRUE);
	acctwatch(a);
        thread_funnel_set(kernel_flock, FALSE);
}


/*
 * Periodically check the file system to see if accounting
 * should be turned on or off.  Beware the case where the vnode
 * has been vgone()'d out from underneath us, e.g. when the file
 * system containing the accounting file has been forcibly unmounted.
 */
/* ARGSUSED */
void
acctwatch(a)
	void *a;
{
	struct statfs sb;

	if (savacctp != NULLVP) {
		if (savacctp->v_type == VBAD) {
			(void) vn_close(savacctp, FWRITE, NOCRED, NULL);
			savacctp = NULLVP;
			return;
		}
		(void)VFS_STATFS(savacctp->v_mount, &sb, (struct proc *)0);
		if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
			acctp = savacctp;
			savacctp = NULLVP;
			log(LOG_NOTICE, "Accounting resumed\n");
		}
	} else if (acctp != NULLVP) {
		if (acctp->v_type == VBAD) {
			(void) vn_close(acctp, FWRITE, NOCRED, NULL);
			acctp = NULLVP;
			return;
		}
		(void)VFS_STATFS(acctp->v_mount, &sb, (struct proc *)0);
		if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
			savacctp = acctp;
			acctp = NULLVP;
			log(LOG_NOTICE, "Accounting suspended\n");
		}
	} else {
		return;
        }
        
	timeout(acctwatch_funnel, NULL, acctchkfreq * hz);
}
Commit	Line	Data
1c79356b A	1	/*
	2	* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
d7e50217	6	* Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
1c79356b	7	*
d7e50217 A	8	* This file contains Original Code and/or Modifications of Original Code
	9	* as defined in and that are subject to the Apple Public Source License
	10	* Version 2.0 (the 'License'). You may not use this file except in
	11	* compliance with the License. Please obtain a copy of the License at
	12	* http://www.opensource.apple.com/apsl/ and read it before using this
	13	* file.
	14	*
	15	* The Original Code and all software distributed under the License are
	16	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
1c79356b A	17	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
1c79356b A	18	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
d7e50217 A	19	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	20	* Please see the License for the specific language governing rights and
	21	* limitations under the License.
1c79356b A	22	*
	23	* @APPLE_LICENSE_HEADER_END@
	24	*/
	25	/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
	26	/*-
	27	* Copyright (c) 1982, 1986, 1989, 1993
	28	* The Regents of the University of California. All rights reserved.
	29	* (c) UNIX System Laboratories, Inc.
	30	* All or some portions of this file are derived from material licensed
	31	* to the University of California by American Telephone and Telegraph
	32	* Co. or Unix System Laboratories, Inc. and are reproduced herein with
	33	* the permission of UNIX System Laboratories, Inc.
	34	*
	35	* Redistribution and use in source and binary forms, with or without
	36	* modification, are permitted provided that the following conditions
	37	* are met:
	38	* 1. Redistributions of source code must retain the above copyright
	39	* notice, this list of conditions and the following disclaimer.
	40	* 2. Redistributions in binary form must reproduce the above copyright
	41	* notice, this list of conditions and the following disclaimer in the
	42	* documentation and/or other materials provided with the distribution.
	43	* 3. All advertising materials mentioning features or use of this software
	44	* must display the following acknowledgement:
	45	* This product includes software developed by the University of
	46	* California, Berkeley and its contributors.
	47	* 4. Neither the name of the University nor the names of its contributors
	48	* may be used to endorse or promote products derived from this software
	49	* without specific prior written permission.
	50	*
	51	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	52	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	53	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	54	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	55	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	56	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	57	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	58	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	59	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	60	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	61	* SUCH DAMAGE.
	62	*
	63	* @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
	64	*/
	65	/* HISTORY
	66	* 08-May-95 Mac Gillon (mgillon) at NeXT
	67	* Purged old history
	68	* New version based on 4.4
	69	*/
	70
	71
	72	#include <sys/param.h>
	73	#include <sys/proc.h>
	74	#include <sys/mount.h>
	75	#include <sys/vnode.h>
	76	#include <sys/file.h>
	77	#include <sys/syslog.h>
	78	#include <sys/kernel.h>
	79	#include <sys/namei.h>
	80	#include <sys/errno.h>
	81	#include <sys/acct.h>
	82	#include <sys/resourcevar.h>
	83	#include <sys/ioctl.h>
	84	#include <sys/tty.h>
	85
86	/*
87	* The routines implemented in this file are described in:
88	* Leffler, et al.: The Design and Implementation of the 4.3BSD
89	* UNIX Operating System (Addison Welley, 1989)
90	* on pages 62-63.
91	*
92	* Arguably, to simplify accounting operations, this mechanism should
93	* be replaced by one in which an accounting log file (similar to /dev/klog)
94	* is read by a user process, etc. However, that has its own problems.
95	*/
96
97	/*
98	* Internal accounting functions.
99	* The former's operation is described in Leffler, et al., and the latter
100	* was provided by UCB with the 4.4BSD-Lite release
101	*/
102	comp_t encode_comp_t __P((u_long, u_long));
103	void acctwatch __P((void *));
104	void acctwatch_funnel __P((void *));
105
106	/*
107	* Accounting vnode pointer, and saved vnode pointer.
108	*/
109	struct vnode *acctp;
110	struct vnode *savacctp;
111
112	/*
113	* Values associated with enabling and disabling accounting
114	*/
115	int acctsuspend = 2; /* stop accounting when < 2% free space left */
116	int acctresume = 4; /* resume when free space risen to > 4% */
117	int acctchkfreq = 15; /* frequency (in seconds) to check space */
118
119	/*
120	* Accounting system call. Written based on the specification and
121	* previous implementation done by Mark Tinguely.
122	*/
123	struct acct_args {
124	char *path;
125	};
126	acct(p, uap, retval)
127	struct proc *p;
128	struct acct_args *uap;
129	int *retval;
130	{
131	struct nameidata nd;
132	int error;
133
134	/* Make sure that the caller is root. */
135	if (error = suser(p->p_ucred, &p->p_acflag))
136	return (error);
137
138	/*
139	* If accounting is to be started to a file, open that file for
140	* writing and make sure it's a 'normal'.
141	*/
142	if (uap->path != NULL) {
143	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, p);
144	if (error = vn_open(&nd, FWRITE, 0))
145	return (error);
146	VOP_UNLOCK(nd.ni_vp, 0, p);
147	if (nd.ni_vp->v_type != VREG) {
148	vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
149	return (EACCES);
150	}
151	}
152
153	/*
154	* If accounting was previously enabled, kill the old space-watcher,
155	* close the file, and (if no new file was specified, leave).
156	*/
157	if (acctp != NULLVP \|\| savacctp != NULLVP) {
158	untimeout(acctwatch_funnel, NULL);
159	error = vn_close((acctp != NULLVP ? acctp : savacctp), FWRITE,
160	p->p_ucred, p);
161	acctp = savacctp = NULLVP;
162	}
163	if (uap->path == NULL)
164	return (error);
165
166	/*
167	* Save the new accounting file vnode, and schedule the new
168	* free space watcher.
169	*/
170	acctp = nd.ni_vp;
171	acctwatch(NULL);
172	return (error);
173	}
174
175	/*
176	* Write out process accounting information, on process exit.
177	* Data to be written out is specified in Leffler, et al.
178	* and are enumerated below. (They're also noted in the system
179	* "acct.h" header file.)
180	*/
181	acct_process(p)
182	struct proc *p;
183	{
184	struct acct acct;
185	struct rusage *r;
186	struct timeval ut, st, tmp;
187	int s, t;
188	struct vnode *vp;
189
190	/* If accounting isn't enabled, don't bother */
191	vp = acctp;
192	if (vp == NULLVP)
193	return (0);
194
195	/*
196	* Get process accounting information.
197	*/
198
199	/* (1) The name of the command that ran */
200	bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
201
202	/* (2) The amount of user and system time that was used */
203	calcru(p, &ut, &st, NULL);
204	acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
205	acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
206
207	/* (3) The elapsed time the commmand ran (and its starting time) */
208	acct.ac_btime = p->p_stats->p_start.tv_sec;
209	s = splclock();
210	tmp = time;
211	splx(s);
212	timevalsub(&tmp, &p->p_stats->p_start);
213	acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
214
215	/* (4) The average amount of memory used */
216	r = &p->p_stats->p_ru;
217	tmp = ut;
218	timevaladd(&tmp, &st);
219	t = tmp.tv_sec * hz + tmp.tv_usec / tick;
220	if (t)
221	acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
222	else
223	acct.ac_mem = 0;
224
225	/* (5) The number of disk I/O operations done */
226	acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
227
228	/* (6) The UID and GID of the process */
229	acct.ac_uid = p->p_cred->p_ruid;
230	acct.ac_gid = p->p_cred->p_rgid;
231
232	/* (7) The terminal from which the process was started */
233	if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
234	acct.ac_tty = p->p_pgrp->pg_session->s_ttyp->t_dev;
235	else
236	acct.ac_tty = NODEV;
237
238	/* (8) The boolean flags that tell how the process terminated, etc. */
239	acct.ac_flag = p->p_acflag;
240
241	/*
242	* Now, just write the accounting information to the file.
243	*/
244	VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE);
245	return (vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
246	(off_t)0, UIO_SYSSPACE, IO_APPEND\|IO_UNIT, p->p_ucred,
247	(int *)0, p));
248	}
249
250	/*
251	* Encode_comp_t converts from ticks in seconds and microseconds
252	* to ticks in 1/AHZ seconds. The encoding is described in
253	* Leffler, et al., on page 63.
254	*/
255
256	#define MANTSIZE 13 /* 13 bit mantissa. */
257	#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
258	#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
259
260	comp_t
261	encode_comp_t(s, us)
262	u_long s, us;
263	{
264	int exp, rnd;
265
266	exp = 0;
267	rnd = 0;
268	s *= AHZ;
269	s += us / (1000000 / AHZ); /* Maximize precision. */
270
271	while (s > MAXFRACT) {
272	rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
273	s >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
274	exp++;
275	}
276
277	/* If we need to round up, do it (and handle overflow correctly). */
278	if (rnd && (++s > MAXFRACT)) {
279	s >>= EXPSIZE;
280	exp++;
281	}
282
283	/* Clean it up and polish it off. */
284	exp <<= MANTSIZE; /* Shift the exponent into place */
285	exp += s; /* and add on the mantissa. */
286	return (exp);
287	}
288
289	void
290	acctwatch_funnel(a)
291	void *a;
292	{
293	thread_funnel_set(kernel_flock, TRUE);
294	acctwatch(a);
295	thread_funnel_set(kernel_flock, FALSE);
296	}
297
298
299	/*
300	* Periodically check the file system to see if accounting
301	* should be turned on or off. Beware the case where the vnode
302	* has been vgone()'d out from underneath us, e.g. when the file
303	* system containing the accounting file has been forcibly unmounted.
304	*/
305	/* ARGSUSED */
306	void
307	acctwatch(a)
308	void *a;
309	{
310	struct statfs sb;
311
312	if (savacctp != NULLVP) {
313	if (savacctp->v_type == VBAD) {
314	(void) vn_close(savacctp, FWRITE, NOCRED, NULL);
315	savacctp = NULLVP;
316	return;
317	}
318	(void)VFS_STATFS(savacctp->v_mount, &sb, (struct proc *)0);
319	if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
320	acctp = savacctp;
321	savacctp = NULLVP;
322	log(LOG_NOTICE, "Accounting resumed\n");
323	}
324	} else if (acctp != NULLVP) {
325	if (acctp->v_type == VBAD) {
326	(void) vn_close(acctp, FWRITE, NOCRED, NULL);
327	acctp = NULLVP;
328	return;
329	}
330	(void)VFS_STATFS(acctp->v_mount, &sb, (struct proc *)0);
331	if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
332	savacctp = acctp;
333	acctp = NULLVP;
334	log(LOG_NOTICE, "Accounting suspended\n");
335	}
336	} else {
337	return;
338	}
339
340	timeout(acctwatch_funnel, NULL, acctchkfreq * hz);
341	}