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