2 * Copyright (c) 1982, 1986, 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
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7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
10 * Copyright (c) 1994 Christopher G. Demetriou
11 * Copyright (c) 2005 Robert N. M. Watson
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41 * @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD$");
49 #include <sys/param.h>
50 #include <sys/systm.h>
52 #include <sys/fcntl.h>
53 #include <sys/kernel.h>
54 #include <sys/kthread.h>
57 #include <sys/mount.h>
58 #include <sys/mutex.h>
59 #include <sys/namei.h>
61 #include <sys/resourcevar.h>
62 #include <sys/sched.h>
64 #include <sys/sysctl.h>
65 #include <sys/sysent.h>
66 #include <sys/syslog.h>
67 #include <sys/sysproto.h>
69 #include <sys/vnode.h>
72 * The routines implemented in this file are described in:
73 * Leffler, et al.: The Design and Implementation of the 4.3BSD
74 * UNIX Operating System (Addison Welley, 1989)
77 * Arguably, to simplify accounting operations, this mechanism should
78 * be replaced by one in which an accounting log file (similar to /dev/klog)
79 * is read by a user process, etc. However, that has its own problems.
83 * Internal accounting functions.
84 * The former's operation is described in Leffler, et al., and the latter
85 * was provided by UCB with the 4.4BSD-Lite release
87 static comp_t encode_comp_t(u_long, u_long);
88 static void acctwatch(void);
89 static void acct_thread(void *);
90 static int acct_disable(struct thread *);
93 * Accounting vnode pointer, saved vnode pointer, and flags for each.
94 * acct_sx protects against changes to the active vnode and credentials
95 * while accounting records are being committed to disk.
97 static int acct_configured;
98 static int acct_suspended;
99 static struct vnode *acct_vp;
100 static struct ucred *acct_cred;
101 static int acct_flags;
102 static struct sx acct_sx;
104 SX_SYSINIT(acct, &acct_sx, "acct_sx");
107 * State of the accounting kthread.
109 static int acct_state;
111 #define ACCT_RUNNING 1 /* Accounting kthread is running. */
112 #define ACCT_EXITREQ 2 /* Accounting kthread should exit. */
115 * Values associated with enabling and disabling accounting
117 static int acctsuspend = 2; /* stop accounting when < 2% free space left */
118 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
119 &acctsuspend, 0, "percentage of free disk space below which accounting stops");
121 static int acctresume = 4; /* resume when free space risen to > 4% */
122 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
123 &acctresume, 0, "percentage of free disk space above which accounting resumes");
125 static int acctchkfreq = 15; /* frequency (in seconds) to check space */
128 sysctl_acct_chkfreq(SYSCTL_HANDLER_ARGS)
132 /* Write out the old value. */
133 error = SYSCTL_OUT(req, &acctchkfreq, sizeof(int));
134 if (error || req->newptr == NULL)
137 /* Read in and verify the new value. */
138 error = SYSCTL_IN(req, &value, sizeof(int));
146 SYSCTL_PROC(_kern, OID_AUTO, acct_chkfreq, CTLTYPE_INT|CTLFLAG_RW,
147 &acctchkfreq, 0, sysctl_acct_chkfreq, "I",
148 "frequency for checking the free space");
150 SYSCTL_INT(_kern, OID_AUTO, acct_configured, CTLFLAG_RD, &acct_configured, 0,
151 "Accounting configured or not");
153 SYSCTL_INT(_kern, OID_AUTO, acct_suspended, CTLFLAG_RD, &acct_suspended, 0,
154 "Accounting suspended or not");
157 * Accounting system call. Written based on the specification and
158 * previous implementation done by Mark Tinguely.
163 acct(struct thread *td, struct acct_args *uap)
166 int error, flags, vfslocked;
168 /* Make sure that the caller is root. */
174 * If accounting is to be started to a file, open that file for
175 * appending and make sure it's a 'normal'.
177 if (uap->path != NULL) {
178 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE | AUDITVNODE1,
179 UIO_USERSPACE, uap->path, td);
180 flags = FWRITE | O_APPEND;
181 error = vn_open(&nd, &flags, 0, -1);
184 vfslocked = NDHASGIANT(&nd);
185 NDFREE(&nd, NDF_ONLY_PNBUF);
187 error = mac_check_system_acct(td->td_ucred, nd.ni_vp);
189 VOP_UNLOCK(nd.ni_vp, 0, td);
190 vn_close(nd.ni_vp, flags, td->td_ucred, td);
191 VFS_UNLOCK_GIANT(vfslocked);
195 VOP_UNLOCK(nd.ni_vp, 0, td);
196 if (nd.ni_vp->v_type != VREG) {
197 vn_close(nd.ni_vp, flags, td->td_ucred, td);
198 VFS_UNLOCK_GIANT(vfslocked);
201 VFS_UNLOCK_GIANT(vfslocked);
204 error = mac_check_system_acct(td->td_ucred, NULL);
211 * Disallow concurrent access to the accounting vnode while we swap
212 * it out, in order to prevent access after close.
217 * If accounting was previously enabled, kill the old space-watcher,
218 * close the file, and (if no new file was specified, leave). Reset
219 * the suspended state regardless of whether accounting remains
223 if (acct_vp != NULL) {
224 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
225 error = acct_disable(td);
226 VFS_UNLOCK_GIANT(vfslocked);
228 if (uap->path == NULL) {
229 if (acct_state & ACCT_RUNNING) {
230 acct_state |= ACCT_EXITREQ;
233 sx_xunlock(&acct_sx);
238 * Save the new accounting file vnode, and schedule the new
239 * free space watcher.
242 acct_cred = crhold(td->td_ucred);
244 if (acct_state & ACCT_RUNNING)
245 acct_state &= ~ACCT_EXITREQ;
248 * Try to start up an accounting kthread. We may start more
249 * than one, but if so the extras will commit suicide as
250 * soon as they start up.
252 error = kthread_create(acct_thread, NULL, NULL, 0, 0,
255 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
256 (void) vn_close(acct_vp, acct_flags, acct_cred, td);
257 VFS_UNLOCK_GIANT(vfslocked);
263 sx_xunlock(&acct_sx);
264 log(LOG_NOTICE, "Unable to start accounting thread\n");
269 sx_xunlock(&acct_sx);
270 log(LOG_NOTICE, "Accounting enabled\n");
275 * Disable currently in-progress accounting by closing the vnode, dropping
276 * our reference to the credential, and clearing the vnode's flags.
279 acct_disable(struct thread *td)
283 sx_assert(&acct_sx, SX_XLOCKED);
284 error = vn_close(acct_vp, acct_flags, acct_cred, td);
290 log(LOG_NOTICE, "Accounting disabled\n");
295 * Write out process accounting information, on process exit.
296 * Data to be written out is specified in Leffler, et al.
297 * and are enumerated below. (They're also noted in the system
298 * "acct.h" header file.)
301 acct_process(struct thread *td)
304 struct timeval ut, st, tmp;
305 struct plimit *newlim, *oldlim;
308 int t, ret, vfslocked;
311 * Lockless check of accounting condition before doing the hard
314 if (acct_vp == NULL || acct_suspended)
320 * If accounting isn't enabled, don't bother. Have to check again
321 * once we own the lock in case we raced with disabling of accounting
324 if (acct_vp == NULL || acct_suspended) {
325 sx_sunlock(&acct_sx);
332 * Get process accounting information.
336 /* (1) The name of the command that ran */
337 bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
339 /* (2) The amount of user and system time that was used */
341 acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
342 acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
344 /* (3) The elapsed time the command ran (and its starting time) */
346 timevaladd(&tmp, &p->p_stats->p_start);
347 acct.ac_btime = tmp.tv_sec;
349 timevalsub(&tmp, &p->p_stats->p_start);
350 acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
352 /* (4) The average amount of memory used */
353 r = &p->p_stats->p_ru;
355 timevaladd(&tmp, &st);
356 t = tmp.tv_sec * hz + tmp.tv_usec / tick;
358 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
362 /* (5) The number of disk I/O operations done */
363 acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
365 /* (6) The UID and GID of the process */
366 acct.ac_uid = p->p_ucred->cr_ruid;
367 acct.ac_gid = p->p_ucred->cr_rgid;
369 /* (7) The terminal from which the process was started */
370 SESS_LOCK(p->p_session);
371 if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
372 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev);
375 SESS_UNLOCK(p->p_session);
377 /* (8) The boolean flags that tell how the process terminated, etc. */
378 acct.ac_flag = p->p_acflag;
382 * Eliminate any file size rlimit.
384 newlim = lim_alloc();
387 lim_copy(newlim, oldlim);
388 newlim->pl_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
394 * Write the accounting information to the file.
396 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
397 VOP_LEASE(acct_vp, td, acct_cred, LEASE_WRITE);
398 ret = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct, sizeof (acct),
399 (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, acct_cred, NOCRED,
401 VFS_UNLOCK_GIANT(vfslocked);
402 sx_sunlock(&acct_sx);
407 * Encode_comp_t converts from ticks in seconds and microseconds
408 * to ticks in 1/AHZ seconds. The encoding is described in
409 * Leffler, et al., on page 63.
412 #define MANTSIZE 13 /* 13 bit mantissa. */
413 #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
414 #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
417 encode_comp_t(u_long s, u_long us)
424 s += us / (1000000 / AHZ); /* Maximize precision. */
426 while (s > MAXFRACT) {
427 rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
428 s >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
432 /* If we need to round up, do it (and handle overflow correctly). */
433 if (rnd && (++s > MAXFRACT)) {
438 /* Clean it up and polish it off. */
439 exp <<= MANTSIZE; /* Shift the exponent into place */
440 exp += s; /* and add on the mantissa. */
445 * Periodically check the filesystem to see if accounting
446 * should be turned on or off. Beware the case where the vnode
447 * has been vgone()'d out from underneath us, e.g. when the file
448 * system containing the accounting file has been forcibly unmounted.
457 sx_assert(&acct_sx, SX_XLOCKED);
460 * If accounting was disabled before our kthread was scheduled,
461 * then acct_vp might be NULL. If so, just ask our kthread to
464 if (acct_vp == NULL) {
465 acct_state |= ACCT_EXITREQ;
470 * If our vnode is no longer valid, tear it down and signal the
471 * accounting thread to die.
473 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
474 if (acct_vp->v_type == VBAD) {
475 (void) acct_disable(NULL);
476 VFS_UNLOCK_GIANT(vfslocked);
477 acct_state |= ACCT_EXITREQ;
482 * Stopping here is better than continuing, maybe it will be VBAD
485 if (VFS_STATFS(acct_vp->v_mount, &sb, curthread) < 0) {
486 VFS_UNLOCK_GIANT(vfslocked);
489 VFS_UNLOCK_GIANT(vfslocked);
490 if (acct_suspended) {
491 if (sb.f_bavail > (int64_t)(acctresume * sb.f_blocks /
494 log(LOG_NOTICE, "Accounting resumed\n");
497 if (sb.f_bavail <= (int64_t)(acctsuspend * sb.f_blocks /
500 log(LOG_NOTICE, "Accounting suspended\n");
506 * The main loop for the dedicated kernel thread that periodically calls
510 acct_thread(void *dummy)
514 /* This is a low-priority kernel thread. */
516 mtx_lock_spin(&sched_lock);
517 sched_prio(curthread, pri);
518 mtx_unlock_spin(&sched_lock);
520 /* If another accounting kthread is already running, just die. */
522 if (acct_state & ACCT_RUNNING) {
523 sx_xunlock(&acct_sx);
526 acct_state |= ACCT_RUNNING;
528 /* Loop until we are asked to exit. */
529 while (!(acct_state & ACCT_EXITREQ)) {
531 /* Perform our periodic checks. */
535 * We check this flag again before sleeping since the
536 * acctwatch() might have shut down accounting and asked us
539 if (!(acct_state & ACCT_EXITREQ)) {
540 sx_xunlock(&acct_sx);
541 tsleep(&acct_state, pri, "-", acctchkfreq * hz);
547 * Acknowledge the exit request and shutdown. We clear both the
548 * exit request and running flags.
551 sx_xunlock(&acct_sx);