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/7.3/sys/kern/kern_alq.c 180695 2008-07-22 14:27:47Z rwatson $");
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/mount.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 #include <security/mac/mac_framework.h>
49
50 /* Async. Logging Queue */
51 struct alq {
52 int aq_entmax; /* Max entries */
53 int aq_entlen; /* Entry length */
54 char *aq_entbuf; /* Buffer for stored entries */
55 int aq_flags; /* Queue flags */
56 struct mtx aq_mtx; /* Queue lock */
57 struct vnode *aq_vp; /* Open vnode handle */
58 struct ucred *aq_cred; /* Credentials of the opening thread */
59 struct ale *aq_first; /* First ent */
60 struct ale *aq_entfree; /* First free ent */
61 struct ale *aq_entvalid; /* First ent valid for writing */
62 LIST_ENTRY(alq) aq_act; /* List of active queues */
63 LIST_ENTRY(alq) aq_link; /* List of all queues */
64 };
65
66 #define AQ_WANTED 0x0001 /* Wakeup sleeper when io is done */
67 #define AQ_ACTIVE 0x0002 /* on the active list */
68 #define AQ_FLUSHING 0x0004 /* doing IO */
69 #define AQ_SHUTDOWN 0x0008 /* Queue no longer valid */
70
71 #define ALQ_LOCK(alq) mtx_lock_spin(&(alq)->aq_mtx)
72 #define ALQ_UNLOCK(alq) mtx_unlock_spin(&(alq)->aq_mtx)
73
74 static MALLOC_DEFINE(M_ALD, "ALD", "ALD");
75
76 /*
77 * The ald_mtx protects the ald_queues list and the ald_active list.
78 */
79 static struct mtx ald_mtx;
80 static LIST_HEAD(, alq) ald_queues;
81 static LIST_HEAD(, alq) ald_active;
82 static int ald_shutingdown = 0;
83 struct thread *ald_thread;
84 static struct proc *ald_proc;
85
86 #define ALD_LOCK() mtx_lock(&ald_mtx)
87 #define ALD_UNLOCK() mtx_unlock(&ald_mtx)
88
89 /* Daemon functions */
90 static int ald_add(struct alq *);
91 static int ald_rem(struct alq *);
92 static void ald_startup(void *);
93 static void ald_daemon(void);
94 static void ald_shutdown(void *, int);
95 static void ald_activate(struct alq *);
96 static void ald_deactivate(struct alq *);
97
98 /* Internal queue functions */
99 static void alq_shutdown(struct alq *);
100 static int alq_doio(struct alq *);
101
102
103 /*
104 * Add a new queue to the global list. Fail if we're shutting down.
105 */
106 static int
107 ald_add(struct alq *alq)
108 {
109 int error;
110
111 error = 0;
112
113 ALD_LOCK();
114 if (ald_shutingdown) {
115 error = EBUSY;
116 goto done;
117 }
118 LIST_INSERT_HEAD(&ald_queues, alq, aq_link);
119 done:
120 ALD_UNLOCK();
121 return (error);
122 }
123
124 /*
125 * Remove a queue from the global list unless we're shutting down. If so,
126 * the ald will take care of cleaning up it's resources.
127 */
128 static int
129 ald_rem(struct alq *alq)
130 {
131 int error;
132
133 error = 0;
134
135 ALD_LOCK();
136 if (ald_shutingdown) {
137 error = EBUSY;
138 goto done;
139 }
140 LIST_REMOVE(alq, aq_link);
141 done:
142 ALD_UNLOCK();
143 return (error);
144 }
145
146 /*
147 * Put a queue on the active list. This will schedule it for writing.
148 */
149 static void
150 ald_activate(struct alq *alq)
151 {
152 LIST_INSERT_HEAD(&ald_active, alq, aq_act);
153 wakeup(&ald_active);
154 }
155
156 static void
157 ald_deactivate(struct alq *alq)
158 {
159 LIST_REMOVE(alq, aq_act);
160 alq->aq_flags &= ~AQ_ACTIVE;
161 }
162
163 static void
164 ald_startup(void *unused)
165 {
166 mtx_init(&ald_mtx, "ALDmtx", NULL, MTX_DEF|MTX_QUIET);
167 LIST_INIT(&ald_queues);
168 LIST_INIT(&ald_active);
169 }
170
171 static void
172 ald_daemon(void)
173 {
174 int needwakeup;
175 struct alq *alq;
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 int vfslocked;
254
255 vp = alq->aq_vp;
256 td = curthread;
257 totlen = 0;
258 iov = 0;
259
260 alstart = ale = alq->aq_entvalid;
261 alq->aq_entvalid = NULL;
262
263 bzero(&aiov, sizeof(aiov));
264 bzero(&auio, sizeof(auio));
265
266 do {
267 if (aiov[iov].iov_base == NULL)
268 aiov[iov].iov_base = ale->ae_data;
269 aiov[iov].iov_len += alq->aq_entlen;
270 totlen += alq->aq_entlen;
271 /* Check to see if we're wrapping the buffer */
272 if (ale->ae_data + alq->aq_entlen != ale->ae_next->ae_data)
273 iov++;
274 ale->ae_flags &= ~AE_VALID;
275 ale = ale->ae_next;
276 } while (ale->ae_flags & AE_VALID);
277
278 alq->aq_flags |= AQ_FLUSHING;
279 ALQ_UNLOCK(alq);
280
281 if (iov == 2 || aiov[iov].iov_base == NULL)
282 iov--;
283
284 auio.uio_iov = &aiov[0];
285 auio.uio_offset = 0;
286 auio.uio_segflg = UIO_SYSSPACE;
287 auio.uio_rw = UIO_WRITE;
288 auio.uio_iovcnt = iov + 1;
289 auio.uio_resid = totlen;
290 auio.uio_td = td;
291
292 /*
293 * Do all of the junk required to write now.
294 */
295 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
296 vn_start_write(vp, &mp, V_WAIT);
297 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
298 VOP_LEASE(vp, td, alq->aq_cred, LEASE_WRITE);
299 /*
300 * XXX: VOP_WRITE error checks are ignored.
301 */
302 #ifdef MAC
303 if (mac_check_vnode_write(alq->aq_cred, NOCRED, vp) == 0)
304 #endif
305 VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, alq->aq_cred);
306 VOP_UNLOCK(vp, 0, td);
307 vn_finished_write(mp);
308 VFS_UNLOCK_GIANT(vfslocked);
309
310 ALQ_LOCK(alq);
311 alq->aq_flags &= ~AQ_FLUSHING;
312
313 if (alq->aq_entfree == NULL)
314 alq->aq_entfree = alstart;
315
316 if (alq->aq_flags & AQ_WANTED) {
317 alq->aq_flags &= ~AQ_WANTED;
318 return (1);
319 }
320
321 return(0);
322 }
323
324 static struct kproc_desc ald_kp = {
325 "ALQ Daemon",
326 ald_daemon,
327 &ald_proc
328 };
329
330 SYSINIT(aldthread, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, kproc_start, &ald_kp);
331 SYSINIT(ald, SI_SUB_LOCK, SI_ORDER_ANY, ald_startup, NULL);
332
333
334 /* User visible queue functions */
335
336 /*
337 * Create the queue data structure, allocate the buffer, and open the file.
338 */
339 int
340 alq_open(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
341 int size, int count)
342 {
343 struct thread *td;
344 struct nameidata nd;
345 struct ale *ale;
346 struct ale *alp;
347 struct alq *alq;
348 char *bufp;
349 int flags;
350 int error;
351 int i, vfslocked;
352
353 *alqp = NULL;
354 td = curthread;
355
356 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_SYSSPACE, file, td);
357 flags = FWRITE | O_NOFOLLOW | O_CREAT;
358
359 error = vn_open_cred(&nd, &flags, cmode, cred, NULL);
360 if (error)
361 return (error);
362
363 vfslocked = NDHASGIANT(&nd);
364 NDFREE(&nd, NDF_ONLY_PNBUF);
365 /* We just unlock so we hold a reference */
366 VOP_UNLOCK(nd.ni_vp, 0, td);
367 VFS_UNLOCK_GIANT(vfslocked);
368
369 alq = malloc(sizeof(*alq), M_ALD, M_WAITOK|M_ZERO);
370 alq->aq_entbuf = malloc(count * size, M_ALD, M_WAITOK|M_ZERO);
371 alq->aq_first = malloc(sizeof(*ale) * count, M_ALD, M_WAITOK|M_ZERO);
372 alq->aq_vp = nd.ni_vp;
373 alq->aq_cred = crhold(cred);
374 alq->aq_entmax = count;
375 alq->aq_entlen = size;
376 alq->aq_entfree = alq->aq_first;
377
378 mtx_init(&alq->aq_mtx, "ALD Queue", NULL, MTX_SPIN|MTX_QUIET);
379
380 bufp = alq->aq_entbuf;
381 ale = alq->aq_first;
382 alp = NULL;
383
384 /* Match up entries with buffers */
385 for (i = 0; i < count; i++) {
386 if (alp)
387 alp->ae_next = ale;
388 ale->ae_data = bufp;
389 alp = ale;
390 ale++;
391 bufp += size;
392 }
393
394 alp->ae_next = alq->aq_first;
395
396 if ((error = ald_add(alq)) != 0)
397 return (error);
398 *alqp = alq;
399
400 return (0);
401 }
402
403 /*
404 * Copy a new entry into the queue. If the operation would block either
405 * wait or return an error depending on the value of waitok.
406 */
407 int
408 alq_write(struct alq *alq, void *data, int waitok)
409 {
410 struct ale *ale;
411
412 if ((ale = alq_get(alq, waitok)) == NULL)
413 return (EWOULDBLOCK);
414
415 bcopy(data, ale->ae_data, alq->aq_entlen);
416 alq_post(alq, ale);
417
418 return (0);
419 }
420
421 struct ale *
422 alq_get(struct alq *alq, int waitok)
423 {
424 struct ale *ale;
425 struct ale *aln;
426
427 ale = NULL;
428
429 ALQ_LOCK(alq);
430
431 /* Loop until we get an entry or we're shutting down */
432 while ((alq->aq_flags & AQ_SHUTDOWN) == 0 &&
433 (ale = alq->aq_entfree) == NULL &&
434 (waitok & ALQ_WAITOK)) {
435 alq->aq_flags |= AQ_WANTED;
436 ALQ_UNLOCK(alq);
437 tsleep(alq, PWAIT, "alqget", 0);
438 ALQ_LOCK(alq);
439 }
440
441 if (ale != NULL) {
442 aln = ale->ae_next;
443 if ((aln->ae_flags & AE_VALID) == 0)
444 alq->aq_entfree = aln;
445 else
446 alq->aq_entfree = NULL;
447 } else
448 ALQ_UNLOCK(alq);
449
450
451 return (ale);
452 }
453
454 void
455 alq_post(struct alq *alq, struct ale *ale)
456 {
457 int activate;
458
459 ale->ae_flags |= AE_VALID;
460
461 if (alq->aq_entvalid == NULL)
462 alq->aq_entvalid = ale;
463
464 if ((alq->aq_flags & AQ_ACTIVE) == 0) {
465 alq->aq_flags |= AQ_ACTIVE;
466 activate = 1;
467 } else
468 activate = 0;
469
470 ALQ_UNLOCK(alq);
471 if (activate) {
472 ALD_LOCK();
473 ald_activate(alq);
474 ALD_UNLOCK();
475 }
476 }
477
478 void
479 alq_flush(struct alq *alq)
480 {
481 int needwakeup = 0;
482
483 ALD_LOCK();
484 ALQ_LOCK(alq);
485 if (alq->aq_flags & AQ_ACTIVE) {
486 ald_deactivate(alq);
487 ALD_UNLOCK();
488 needwakeup = alq_doio(alq);
489 } else
490 ALD_UNLOCK();
491 ALQ_UNLOCK(alq);
492
493 if (needwakeup)
494 wakeup(alq);
495 }
496
497 /*
498 * Flush remaining data, close the file and free all resources.
499 */
500 void
501 alq_close(struct alq *alq)
502 {
503 /*
504 * If we're already shuting down someone else will flush and close
505 * the vnode.
506 */
507 if (ald_rem(alq) != 0)
508 return;
509
510 /*
511 * Drain all pending IO.
512 */
513 alq_shutdown(alq);
514
515 mtx_destroy(&alq->aq_mtx);
516 free(alq->aq_first, M_ALD);
517 free(alq->aq_entbuf, M_ALD);
518 free(alq, M_ALD);
519 }
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