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