FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_alq.c
1 /*-
2 * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: releng/5.4/sys/kern/kern_alq.c 145335 2005-04-20 19:11:07Z cvs2svn $");
29
30 #include "opt_mac.h"
31
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/kernel.h>
35 #include <sys/kthread.h>
36 #include <sys/lock.h>
37 #include <sys/mac.h>
38 #include <sys/mutex.h>
39 #include <sys/namei.h>
40 #include <sys/proc.h>
41 #include <sys/vnode.h>
42 #include <sys/alq.h>
43 #include <sys/malloc.h>
44 #include <sys/unistd.h>
45 #include <sys/fcntl.h>
46 #include <sys/eventhandler.h>
47
48 /* Async. Logging Queue */
49 struct alq {
50 int aq_entmax; /* Max entries */
51 int aq_entlen; /* Entry length */
52 char *aq_entbuf; /* Buffer for stored entries */
53 int aq_flags; /* Queue flags */
54 struct mtx aq_mtx; /* Queue lock */
55 struct vnode *aq_vp; /* Open vnode handle */
56 struct ucred *aq_cred; /* Credentials of the opening thread */
57 struct ale *aq_first; /* First ent */
58 struct ale *aq_entfree; /* First free ent */
59 struct ale *aq_entvalid; /* First ent valid for writing */
60 LIST_ENTRY(alq) aq_act; /* List of active queues */
61 LIST_ENTRY(alq) aq_link; /* List of all queues */
62 };
63
64 #define AQ_WANTED 0x0001 /* Wakeup sleeper when io is done */
65 #define AQ_ACTIVE 0x0002 /* on the active list */
66 #define AQ_FLUSHING 0x0004 /* doing IO */
67 #define AQ_SHUTDOWN 0x0008 /* Queue no longer valid */
68
69 #define ALQ_LOCK(alq) mtx_lock_spin(&(alq)->aq_mtx)
70 #define ALQ_UNLOCK(alq) mtx_unlock_spin(&(alq)->aq_mtx)
71
72 static MALLOC_DEFINE(M_ALD, "ALD", "ALD");
73
74 /*
75 * The ald_mtx protects the ald_queues list and the ald_active list.
76 */
77 static struct mtx ald_mtx;
78 static LIST_HEAD(, alq) ald_queues;
79 static LIST_HEAD(, alq) ald_active;
80 static int ald_shutingdown = 0;
81 struct thread *ald_thread;
82 static struct proc *ald_proc;
83
84 #define ALD_LOCK() mtx_lock(&ald_mtx)
85 #define ALD_UNLOCK() mtx_unlock(&ald_mtx)
86
87 /* Daemon functions */
88 static int ald_add(struct alq *);
89 static int ald_rem(struct alq *);
90 static void ald_startup(void *);
91 static void ald_daemon(void);
92 static void ald_shutdown(void *, int);
93 static void ald_activate(struct alq *);
94 static void ald_deactivate(struct alq *);
95
96 /* Internal queue functions */
97 static void alq_shutdown(struct alq *);
98 static int alq_doio(struct alq *);
99
100
101 /*
102 * Add a new queue to the global list. Fail if we're shutting down.
103 */
104 static int
105 ald_add(struct alq *alq)
106 {
107 int error;
108
109 error = 0;
110
111 ALD_LOCK();
112 if (ald_shutingdown) {
113 error = EBUSY;
114 goto done;
115 }
116 LIST_INSERT_HEAD(&ald_queues, alq, aq_link);
117 done:
118 ALD_UNLOCK();
119 return (error);
120 }
121
122 /*
123 * Remove a queue from the global list unless we're shutting down. If so,
124 * the ald will take care of cleaning up it's resources.
125 */
126 static int
127 ald_rem(struct alq *alq)
128 {
129 int error;
130
131 error = 0;
132
133 ALD_LOCK();
134 if (ald_shutingdown) {
135 error = EBUSY;
136 goto done;
137 }
138 LIST_REMOVE(alq, aq_link);
139 done:
140 ALD_UNLOCK();
141 return (error);
142 }
143
144 /*
145 * Put a queue on the active list. This will schedule it for writing.
146 */
147 static void
148 ald_activate(struct alq *alq)
149 {
150 LIST_INSERT_HEAD(&ald_active, alq, aq_act);
151 wakeup(&ald_active);
152 }
153
154 static void
155 ald_deactivate(struct alq *alq)
156 {
157 LIST_REMOVE(alq, aq_act);
158 alq->aq_flags &= ~AQ_ACTIVE;
159 }
160
161 static void
162 ald_startup(void *unused)
163 {
164 mtx_init(&ald_mtx, "ALDmtx", NULL, MTX_DEF|MTX_QUIET);
165 LIST_INIT(&ald_queues);
166 LIST_INIT(&ald_active);
167 }
168
169 static void
170 ald_daemon(void)
171 {
172 int needwakeup;
173 struct alq *alq;
174
175 mtx_lock(&Giant);
176
177 ald_thread = FIRST_THREAD_IN_PROC(ald_proc);
178
179 EVENTHANDLER_REGISTER(shutdown_pre_sync, ald_shutdown, NULL,
180 SHUTDOWN_PRI_FIRST);
181
182 ALD_LOCK();
183
184 for (;;) {
185 while ((alq = LIST_FIRST(&ald_active)) == NULL)
186 msleep(&ald_active, &ald_mtx, PWAIT, "aldslp", 0);
187
188 ALQ_LOCK(alq);
189 ald_deactivate(alq);
190 ALD_UNLOCK();
191 needwakeup = alq_doio(alq);
192 ALQ_UNLOCK(alq);
193 if (needwakeup)
194 wakeup(alq);
195 ALD_LOCK();
196 }
197 }
198
199 static void
200 ald_shutdown(void *arg, int howto)
201 {
202 struct alq *alq;
203
204 ALD_LOCK();
205 ald_shutingdown = 1;
206
207 while ((alq = LIST_FIRST(&ald_queues)) != NULL) {
208 LIST_REMOVE(alq, aq_link);
209 ALD_UNLOCK();
210 alq_shutdown(alq);
211 ALD_LOCK();
212 }
213 ALD_UNLOCK();
214 }
215
216 static void
217 alq_shutdown(struct alq *alq)
218 {
219 ALQ_LOCK(alq);
220
221 /* Stop any new writers. */
222 alq->aq_flags |= AQ_SHUTDOWN;
223
224 /* Drain IO */
225 while (alq->aq_flags & (AQ_FLUSHING|AQ_ACTIVE)) {
226 alq->aq_flags |= AQ_WANTED;
227 ALQ_UNLOCK(alq);
228 tsleep(alq, PWAIT, "aldclose", 0);
229 ALQ_LOCK(alq);
230 }
231 ALQ_UNLOCK(alq);
232
233 vn_close(alq->aq_vp, FWRITE, alq->aq_cred,
234 curthread);
235 crfree(alq->aq_cred);
236 }
237
238 /*
239 * Flush all pending data to disk. This operation will block.
240 */
241 static int
242 alq_doio(struct alq *alq)
243 {
244 struct thread *td;
245 struct mount *mp;
246 struct vnode *vp;
247 struct uio auio;
248 struct iovec aiov[2];
249 struct ale *ale;
250 struct ale *alstart;
251 int totlen;
252 int iov;
253
254 vp = alq->aq_vp;
255 td = curthread;
256 totlen = 0;
257 iov = 0;
258
259 alstart = ale = alq->aq_entvalid;
260 alq->aq_entvalid = NULL;
261
262 bzero(&aiov, sizeof(aiov));
263 bzero(&auio, sizeof(auio));
264
265 do {
266 if (aiov[iov].iov_base == NULL)
267 aiov[iov].iov_base = ale->ae_data;
268 aiov[iov].iov_len += alq->aq_entlen;
269 totlen += alq->aq_entlen;
270 /* Check to see if we're wrapping the buffer */
271 if (ale->ae_data + alq->aq_entlen != ale->ae_next->ae_data)
272 iov++;
273 ale->ae_flags &= ~AE_VALID;
274 ale = ale->ae_next;
275 } while (ale->ae_flags & AE_VALID);
276
277 alq->aq_flags |= AQ_FLUSHING;
278 ALQ_UNLOCK(alq);
279
280 if (iov == 2 || aiov[iov].iov_base == NULL)
281 iov--;
282
283 auio.uio_iov = &aiov[0];
284 auio.uio_offset = 0;
285 auio.uio_segflg = UIO_SYSSPACE;
286 auio.uio_rw = UIO_WRITE;
287 auio.uio_iovcnt = iov + 1;
288 auio.uio_resid = totlen;
289 auio.uio_td = td;
290
291 /*
292 * Do all of the junk required to write now.
293 */
294 vn_start_write(vp, &mp, V_WAIT);
295 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
296 VOP_LEASE(vp, td, alq->aq_cred, LEASE_WRITE);
297 /*
298 * XXX: VOP_WRITE error checks are ignored.
299 */
300 #ifdef MAC
301 if (mac_check_vnode_write(alq->aq_cred, NOCRED, vp) == 0)
302 #endif
303 VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, alq->aq_cred);
304 VOP_UNLOCK(vp, 0, td);
305 vn_finished_write(mp);
306
307 ALQ_LOCK(alq);
308 alq->aq_flags &= ~AQ_FLUSHING;
309
310 if (alq->aq_entfree == NULL)
311 alq->aq_entfree = alstart;
312
313 if (alq->aq_flags & AQ_WANTED) {
314 alq->aq_flags &= ~AQ_WANTED;
315 return (1);
316 }
317
318 return(0);
319 }
320
321 static struct kproc_desc ald_kp = {
322 "ALQ Daemon",
323 ald_daemon,
324 &ald_proc
325 };
326
327 SYSINIT(aldthread, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, kproc_start, &ald_kp)
328 SYSINIT(ald, SI_SUB_LOCK, SI_ORDER_ANY, ald_startup, NULL)
329
330
331 /* User visible queue functions */
332
333 /*
334 * Create the queue data structure, allocate the buffer, and open the file.
335 */
336 int
337 alq_open(struct alq **alqp, const char *file, struct ucred *cred, int size,
338 int count)
339 {
340 struct thread *td;
341 struct nameidata nd;
342 struct ale *ale;
343 struct ale *alp;
344 struct alq *alq;
345 char *bufp;
346 int flags;
347 int error;
348 int i;
349
350 *alqp = NULL;
351 td = curthread;
352
353 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, file, td);
354 flags = FWRITE | O_NOFOLLOW | O_CREAT;
355
356 error = vn_open_cred(&nd, &flags, 0, cred, -1);
357 if (error)
358 return (error);
359
360 NDFREE(&nd, NDF_ONLY_PNBUF);
361 /* We just unlock so we hold a reference */
362 VOP_UNLOCK(nd.ni_vp, 0, td);
363
364 alq = malloc(sizeof(*alq), M_ALD, M_WAITOK|M_ZERO);
365 alq->aq_entbuf = malloc(count * size, M_ALD, M_WAITOK|M_ZERO);
366 alq->aq_first = malloc(sizeof(*ale) * count, M_ALD, M_WAITOK|M_ZERO);
367 alq->aq_vp = nd.ni_vp;
368 alq->aq_cred = crhold(cred);
369 alq->aq_entmax = count;
370 alq->aq_entlen = size;
371 alq->aq_entfree = alq->aq_first;
372
373 mtx_init(&alq->aq_mtx, "ALD Queue", NULL, MTX_SPIN|MTX_QUIET);
374
375 bufp = alq->aq_entbuf;
376 ale = alq->aq_first;
377 alp = NULL;
378
379 /* Match up entries with buffers */
380 for (i = 0; i < count; i++) {
381 if (alp)
382 alp->ae_next = ale;
383 ale->ae_data = bufp;
384 alp = ale;
385 ale++;
386 bufp += size;
387 }
388
389 alp->ae_next = alq->aq_first;
390
391 if ((error = ald_add(alq)) != 0)
392 return (error);
393 *alqp = alq;
394
395 return (0);
396 }
397
398 /*
399 * Copy a new entry into the queue. If the operation would block either
400 * wait or return an error depending on the value of waitok.
401 */
402 int
403 alq_write(struct alq *alq, void *data, int waitok)
404 {
405 struct ale *ale;
406
407 if ((ale = alq_get(alq, waitok)) == NULL)
408 return (EWOULDBLOCK);
409
410 bcopy(data, ale->ae_data, alq->aq_entlen);
411 alq_post(alq, ale);
412
413 return (0);
414 }
415
416 struct ale *
417 alq_get(struct alq *alq, int waitok)
418 {
419 struct ale *ale;
420 struct ale *aln;
421
422 ale = NULL;
423
424 ALQ_LOCK(alq);
425
426 /* Loop until we get an entry or we're shutting down */
427 while ((alq->aq_flags & AQ_SHUTDOWN) == 0 &&
428 (ale = alq->aq_entfree) == NULL &&
429 (waitok & ALQ_WAITOK)) {
430 alq->aq_flags |= AQ_WANTED;
431 ALQ_UNLOCK(alq);
432 tsleep(alq, PWAIT, "alqget", 0);
433 ALQ_LOCK(alq);
434 }
435
436 if (ale != NULL) {
437 aln = ale->ae_next;
438 if ((aln->ae_flags & AE_VALID) == 0)
439 alq->aq_entfree = aln;
440 else
441 alq->aq_entfree = NULL;
442 } else
443 ALQ_UNLOCK(alq);
444
445
446 return (ale);
447 }
448
449 void
450 alq_post(struct alq *alq, struct ale *ale)
451 {
452 int activate;
453
454 ale->ae_flags |= AE_VALID;
455
456 if (alq->aq_entvalid == NULL)
457 alq->aq_entvalid = ale;
458
459 if ((alq->aq_flags & AQ_ACTIVE) == 0) {
460 alq->aq_flags |= AQ_ACTIVE;
461 activate = 1;
462 } else
463 activate = 0;
464
465 ALQ_UNLOCK(alq);
466 if (activate) {
467 ALD_LOCK();
468 ald_activate(alq);
469 ALD_UNLOCK();
470 }
471 }
472
473 void
474 alq_flush(struct alq *alq)
475 {
476 int needwakeup = 0;
477
478 ALD_LOCK();
479 ALQ_LOCK(alq);
480 if (alq->aq_flags & AQ_ACTIVE) {
481 ald_deactivate(alq);
482 ALD_UNLOCK();
483 needwakeup = alq_doio(alq);
484 } else
485 ALD_UNLOCK();
486 ALQ_UNLOCK(alq);
487
488 if (needwakeup)
489 wakeup(alq);
490 }
491
492 /*
493 * Flush remaining data, close the file and free all resources.
494 */
495 void
496 alq_close(struct alq *alq)
497 {
498 /*
499 * If we're already shuting down someone else will flush and close
500 * the vnode.
501 */
502 if (ald_rem(alq) != 0)
503 return;
504
505 /*
506 * Drain all pending IO.
507 */
508 alq_shutdown(alq);
509
510 mtx_destroy(&alq->aq_mtx);
511 free(alq->aq_first, M_ALD);
512 free(alq->aq_entbuf, M_ALD);
513 free(alq, M_ALD);
514 }
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