1 /* -*- c -*- --------------------------------------------------------------- *
2 *
3 * linux/fs/autofs/waitq.c
4 *
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
7 *
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
11 *
12 * ------------------------------------------------------------------------- */
13
14 #include <linux/slab.h>
15 #include <linux/time.h>
16 #include <linux/signal.h>
17 #include <linux/file.h>
18 #include "autofs_i.h"
19
20 /* We make this a static variable rather than a part of the superblock; it
21 is better if we don't reassign numbers easily even across filesystems */
22 static autofs_wqt_t autofs4_next_wait_queue = 1;
23
24 /* These are the signals we allow interrupting a pending mount */
25 #define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
26
autofs4_catatonic_mode(struct autofs_sb_info * sbi)27 void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
28 {
29 struct autofs_wait_queue *wq, *nwq;
30
31 mutex_lock(&sbi->wq_mutex);
32 if (sbi->catatonic) {
33 mutex_unlock(&sbi->wq_mutex);
34 return;
35 }
36
37 DPRINTK("entering catatonic mode");
38
39 sbi->catatonic = 1;
40 wq = sbi->queues;
41 sbi->queues = NULL; /* Erase all wait queues */
42 while (wq) {
43 nwq = wq->next;
44 wq->status = -ENOENT; /* Magic is gone - report failure */
45 if (wq->name.name) {
46 kfree(wq->name.name);
47 wq->name.name = NULL;
48 }
49 wq->wait_ctr--;
50 wake_up_interruptible(&wq->queue);
51 wq = nwq;
52 }
53 fput(sbi->pipe); /* Close the pipe */
54 sbi->pipe = NULL;
55 sbi->pipefd = -1;
56 mutex_unlock(&sbi->wq_mutex);
57 }
58
autofs4_write(struct autofs_sb_info * sbi,struct file * file,const void * addr,int bytes)59 static int autofs4_write(struct autofs_sb_info *sbi,
60 struct file *file, const void *addr, int bytes)
61 {
62 unsigned long sigpipe, flags;
63 mm_segment_t fs;
64 const char *data = (const char *)addr;
65 ssize_t wr = 0;
66
67 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
68
69 /* Save pointer to user space and point back to kernel space */
70 fs = get_fs();
71 set_fs(KERNEL_DS);
72
73 mutex_lock(&sbi->pipe_mutex);
74 while (bytes &&
75 (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
76 data += wr;
77 bytes -= wr;
78 }
79 mutex_unlock(&sbi->pipe_mutex);
80
81 set_fs(fs);
82
83 /* Keep the currently executing process from receiving a
84 SIGPIPE unless it was already supposed to get one */
85 if (wr == -EPIPE && !sigpipe) {
86 spin_lock_irqsave(¤t->sighand->siglock, flags);
87 sigdelset(¤t->pending.signal, SIGPIPE);
88 recalc_sigpending();
89 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
90 }
91
92 return (bytes > 0);
93 }
94
autofs4_notify_daemon(struct autofs_sb_info * sbi,struct autofs_wait_queue * wq,int type)95 static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
96 struct autofs_wait_queue *wq,
97 int type)
98 {
99 union {
100 struct autofs_packet_hdr hdr;
101 union autofs_packet_union v4_pkt;
102 union autofs_v5_packet_union v5_pkt;
103 } pkt;
104 struct file *pipe = NULL;
105 size_t pktsz;
106
107 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
108 (unsigned long) wq->wait_queue_token, wq->name.len, wq->name.name, type);
109
110 memset(&pkt,0,sizeof pkt); /* For security reasons */
111
112 pkt.hdr.proto_version = sbi->version;
113 pkt.hdr.type = type;
114 mutex_lock(&sbi->wq_mutex);
115
116 /* Check if we have become catatonic */
117 if (sbi->catatonic) {
118 mutex_unlock(&sbi->wq_mutex);
119 return;
120 }
121 switch (type) {
122 /* Kernel protocol v4 missing and expire packets */
123 case autofs_ptype_missing:
124 {
125 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
126
127 pktsz = sizeof(*mp);
128
129 mp->wait_queue_token = wq->wait_queue_token;
130 mp->len = wq->name.len;
131 memcpy(mp->name, wq->name.name, wq->name.len);
132 mp->name[wq->name.len] = '\0';
133 break;
134 }
135 case autofs_ptype_expire_multi:
136 {
137 struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
138
139 pktsz = sizeof(*ep);
140
141 ep->wait_queue_token = wq->wait_queue_token;
142 ep->len = wq->name.len;
143 memcpy(ep->name, wq->name.name, wq->name.len);
144 ep->name[wq->name.len] = '\0';
145 break;
146 }
147 /*
148 * Kernel protocol v5 packet for handling indirect and direct
149 * mount missing and expire requests
150 */
151 case autofs_ptype_missing_indirect:
152 case autofs_ptype_expire_indirect:
153 case autofs_ptype_missing_direct:
154 case autofs_ptype_expire_direct:
155 {
156 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
157
158 pktsz = sizeof(*packet);
159
160 packet->wait_queue_token = wq->wait_queue_token;
161 packet->len = wq->name.len;
162 memcpy(packet->name, wq->name.name, wq->name.len);
163 packet->name[wq->name.len] = '\0';
164 packet->dev = wq->dev;
165 packet->ino = wq->ino;
166 packet->uid = wq->uid;
167 packet->gid = wq->gid;
168 packet->pid = wq->pid;
169 packet->tgid = wq->tgid;
170 break;
171 }
172 default:
173 printk("autofs4_notify_daemon: bad type %d!\n", type);
174 mutex_unlock(&sbi->wq_mutex);
175 return;
176 }
177
178 pipe = sbi->pipe;
179 get_file(pipe);
180
181 mutex_unlock(&sbi->wq_mutex);
182
183 if (autofs4_write(sbi, pipe, &pkt, pktsz))
184 autofs4_catatonic_mode(sbi);
185 fput(pipe);
186 }
187
autofs4_getpath(struct autofs_sb_info * sbi,struct dentry * dentry,char ** name)188 static int autofs4_getpath(struct autofs_sb_info *sbi,
189 struct dentry *dentry, char **name)
190 {
191 struct dentry *root = sbi->sb->s_root;
192 struct dentry *tmp;
193 char *buf;
194 char *p;
195 int len;
196 unsigned seq;
197
198 rename_retry:
199 buf = *name;
200 len = 0;
201
202 seq = read_seqbegin(&rename_lock);
203 rcu_read_lock();
204 spin_lock(&sbi->fs_lock);
205 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
206 len += tmp->d_name.len + 1;
207
208 if (!len || --len > NAME_MAX) {
209 spin_unlock(&sbi->fs_lock);
210 rcu_read_unlock();
211 if (read_seqretry(&rename_lock, seq))
212 goto rename_retry;
213 return 0;
214 }
215
216 *(buf + len) = '\0';
217 p = buf + len - dentry->d_name.len;
218 strncpy(p, dentry->d_name.name, dentry->d_name.len);
219
220 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
221 *(--p) = '/';
222 p -= tmp->d_name.len;
223 strncpy(p, tmp->d_name.name, tmp->d_name.len);
224 }
225 spin_unlock(&sbi->fs_lock);
226 rcu_read_unlock();
227 if (read_seqretry(&rename_lock, seq))
228 goto rename_retry;
229
230 return len;
231 }
232
233 static struct autofs_wait_queue *
autofs4_find_wait(struct autofs_sb_info * sbi,struct qstr * qstr)234 autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
235 {
236 struct autofs_wait_queue *wq;
237
238 for (wq = sbi->queues; wq; wq = wq->next) {
239 if (wq->name.hash == qstr->hash &&
240 wq->name.len == qstr->len &&
241 wq->name.name &&
242 !memcmp(wq->name.name, qstr->name, qstr->len))
243 break;
244 }
245 return wq;
246 }
247
248 /*
249 * Check if we have a valid request.
250 * Returns
251 * 1 if the request should continue.
252 * In this case we can return an autofs_wait_queue entry if one is
253 * found or NULL to idicate a new wait needs to be created.
254 * 0 or a negative errno if the request shouldn't continue.
255 */
validate_request(struct autofs_wait_queue ** wait,struct autofs_sb_info * sbi,struct qstr * qstr,struct dentry * dentry,enum autofs_notify notify)256 static int validate_request(struct autofs_wait_queue **wait,
257 struct autofs_sb_info *sbi,
258 struct qstr *qstr,
259 struct dentry*dentry, enum autofs_notify notify)
260 {
261 struct autofs_wait_queue *wq;
262 struct autofs_info *ino;
263
264 if (sbi->catatonic)
265 return -ENOENT;
266
267 /* Wait in progress, continue; */
268 wq = autofs4_find_wait(sbi, qstr);
269 if (wq) {
270 *wait = wq;
271 return 1;
272 }
273
274 *wait = NULL;
275
276 /* If we don't yet have any info this is a new request */
277 ino = autofs4_dentry_ino(dentry);
278 if (!ino)
279 return 1;
280
281 /*
282 * If we've been asked to wait on an existing expire (NFY_NONE)
283 * but there is no wait in the queue ...
284 */
285 if (notify == NFY_NONE) {
286 /*
287 * Either we've betean the pending expire to post it's
288 * wait or it finished while we waited on the mutex.
289 * So we need to wait till either, the wait appears
290 * or the expire finishes.
291 */
292
293 while (ino->flags & AUTOFS_INF_EXPIRING) {
294 mutex_unlock(&sbi->wq_mutex);
295 schedule_timeout_interruptible(HZ/10);
296 if (mutex_lock_interruptible(&sbi->wq_mutex))
297 return -EINTR;
298
299 if (sbi->catatonic)
300 return -ENOENT;
301
302 wq = autofs4_find_wait(sbi, qstr);
303 if (wq) {
304 *wait = wq;
305 return 1;
306 }
307 }
308
309 /*
310 * Not ideal but the status has already gone. Of the two
311 * cases where we wait on NFY_NONE neither depend on the
312 * return status of the wait.
313 */
314 return 0;
315 }
316
317 /*
318 * If we've been asked to trigger a mount and the request
319 * completed while we waited on the mutex ...
320 */
321 if (notify == NFY_MOUNT) {
322 struct dentry *new = NULL;
323 int valid = 1;
324
325 /*
326 * If the dentry was successfully mounted while we slept
327 * on the wait queue mutex we can return success. If it
328 * isn't mounted (doesn't have submounts for the case of
329 * a multi-mount with no mount at it's base) we can
330 * continue on and create a new request.
331 */
332 if (!IS_ROOT(dentry)) {
333 if (dentry->d_inode && d_unhashed(dentry)) {
334 struct dentry *parent = dentry->d_parent;
335 new = d_lookup(parent, &dentry->d_name);
336 if (new)
337 dentry = new;
338 }
339 }
340 if (have_submounts(dentry))
341 valid = 0;
342
343 if (new)
344 dput(new);
345 return valid;
346 }
347
348 return 1;
349 }
350
autofs4_wait(struct autofs_sb_info * sbi,struct dentry * dentry,enum autofs_notify notify)351 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
352 enum autofs_notify notify)
353 {
354 struct autofs_wait_queue *wq;
355 struct qstr qstr;
356 char *name;
357 int status, ret, type;
358
359 /* In catatonic mode, we don't wait for nobody */
360 if (sbi->catatonic)
361 return -ENOENT;
362
363 if (!dentry->d_inode) {
364 /*
365 * A wait for a negative dentry is invalid for certain
366 * cases. A direct or offset mount "always" has its mount
367 * point directory created and so the request dentry must
368 * be positive or the map key doesn't exist. The situation
369 * is very similar for indirect mounts except only dentrys
370 * in the root of the autofs file system may be negative.
371 */
372 if (autofs_type_trigger(sbi->type))
373 return -ENOENT;
374 else if (!IS_ROOT(dentry->d_parent))
375 return -ENOENT;
376 }
377
378 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
379 if (!name)
380 return -ENOMEM;
381
382 /* If this is a direct mount request create a dummy name */
383 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
384 qstr.len = sprintf(name, "%p", dentry);
385 else {
386 qstr.len = autofs4_getpath(sbi, dentry, &name);
387 if (!qstr.len) {
388 kfree(name);
389 return -ENOENT;
390 }
391 }
392 qstr.name = name;
393 qstr.hash = full_name_hash(name, qstr.len);
394
395 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
396 kfree(qstr.name);
397 return -EINTR;
398 }
399
400 ret = validate_request(&wq, sbi, &qstr, dentry, notify);
401 if (ret <= 0) {
402 if (ret != -EINTR)
403 mutex_unlock(&sbi->wq_mutex);
404 kfree(qstr.name);
405 return ret;
406 }
407
408 if (!wq) {
409 /* Create a new wait queue */
410 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
411 if (!wq) {
412 kfree(qstr.name);
413 mutex_unlock(&sbi->wq_mutex);
414 return -ENOMEM;
415 }
416
417 wq->wait_queue_token = autofs4_next_wait_queue;
418 if (++autofs4_next_wait_queue == 0)
419 autofs4_next_wait_queue = 1;
420 wq->next = sbi->queues;
421 sbi->queues = wq;
422 init_waitqueue_head(&wq->queue);
423 memcpy(&wq->name, &qstr, sizeof(struct qstr));
424 wq->dev = autofs4_get_dev(sbi);
425 wq->ino = autofs4_get_ino(sbi);
426 wq->uid = current_uid();
427 wq->gid = current_gid();
428 wq->pid = current->pid;
429 wq->tgid = current->tgid;
430 wq->status = -EINTR; /* Status return if interrupted */
431 wq->wait_ctr = 2;
432 mutex_unlock(&sbi->wq_mutex);
433
434 if (sbi->version < 5) {
435 if (notify == NFY_MOUNT)
436 type = autofs_ptype_missing;
437 else
438 type = autofs_ptype_expire_multi;
439 } else {
440 if (notify == NFY_MOUNT)
441 type = autofs_type_trigger(sbi->type) ?
442 autofs_ptype_missing_direct :
443 autofs_ptype_missing_indirect;
444 else
445 type = autofs_type_trigger(sbi->type) ?
446 autofs_ptype_expire_direct :
447 autofs_ptype_expire_indirect;
448 }
449
450 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
451 (unsigned long) wq->wait_queue_token, wq->name.len,
452 wq->name.name, notify);
453
454 /* autofs4_notify_daemon() may block */
455 autofs4_notify_daemon(sbi, wq, type);
456 } else {
457 wq->wait_ctr++;
458 mutex_unlock(&sbi->wq_mutex);
459 kfree(qstr.name);
460 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
461 (unsigned long) wq->wait_queue_token, wq->name.len,
462 wq->name.name, notify);
463 }
464
465 /*
466 * wq->name.name is NULL iff the lock is already released
467 * or the mount has been made catatonic.
468 */
469 if (wq->name.name) {
470 /* Block all but "shutdown" signals while waiting */
471 sigset_t oldset;
472 unsigned long irqflags;
473
474 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
475 oldset = current->blocked;
476 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
477 recalc_sigpending();
478 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
479
480 wait_event_interruptible(wq->queue, wq->name.name == NULL);
481
482 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
483 current->blocked = oldset;
484 recalc_sigpending();
485 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
486 } else {
487 DPRINTK("skipped sleeping");
488 }
489
490 status = wq->status;
491
492 /*
493 * For direct and offset mounts we need to track the requester's
494 * uid and gid in the dentry info struct. This is so it can be
495 * supplied, on request, by the misc device ioctl interface.
496 * This is needed during daemon resatart when reconnecting
497 * to existing, active, autofs mounts. The uid and gid (and
498 * related string values) may be used for macro substitution
499 * in autofs mount maps.
500 */
501 if (!status) {
502 struct autofs_info *ino;
503 struct dentry *de = NULL;
504
505 /* direct mount or browsable map */
506 ino = autofs4_dentry_ino(dentry);
507 if (!ino) {
508 /* If not lookup actual dentry used */
509 de = d_lookup(dentry->d_parent, &dentry->d_name);
510 if (de)
511 ino = autofs4_dentry_ino(de);
512 }
513
514 /* Set mount requester */
515 if (ino) {
516 spin_lock(&sbi->fs_lock);
517 ino->uid = wq->uid;
518 ino->gid = wq->gid;
519 spin_unlock(&sbi->fs_lock);
520 }
521
522 if (de)
523 dput(de);
524 }
525
526 /* Are we the last process to need status? */
527 mutex_lock(&sbi->wq_mutex);
528 if (!--wq->wait_ctr)
529 kfree(wq);
530 mutex_unlock(&sbi->wq_mutex);
531
532 return status;
533 }
534
535
autofs4_wait_release(struct autofs_sb_info * sbi,autofs_wqt_t wait_queue_token,int status)536 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
537 {
538 struct autofs_wait_queue *wq, **wql;
539
540 mutex_lock(&sbi->wq_mutex);
541 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
542 if (wq->wait_queue_token == wait_queue_token)
543 break;
544 }
545
546 if (!wq) {
547 mutex_unlock(&sbi->wq_mutex);
548 return -EINVAL;
549 }
550
551 *wql = wq->next; /* Unlink from chain */
552 kfree(wq->name.name);
553 wq->name.name = NULL; /* Do not wait on this queue */
554 wq->status = status;
555 wake_up_interruptible(&wq->queue);
556 if (!--wq->wait_ctr)
557 kfree(wq);
558 mutex_unlock(&sbi->wq_mutex);
559
560 return 0;
561 }
562
563