1 /* -*- c -*- --------------------------------------------------------------- *
3 * linux/fs/autofs/waitq.c
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
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.
12 * ------------------------------------------------------------------------- */
14 #include <linux/slab.h>
15 #include <linux/time.h>
16 #include <linux/signal.h>
17 #include <linux/file.h>
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;
24 /* These are the signals we allow interrupting a pending mount */
25 #define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
27 void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
29 struct autofs_wait_queue *wq, *nwq;
31 mutex_lock(&sbi->wq_mutex);
33 mutex_unlock(&sbi->wq_mutex);
37 DPRINTK("entering catatonic mode");
41 sbi->queues = NULL; /* Erase all wait queues */
44 wq->status = -ENOENT; /* Magic is gone - report failure */
50 wake_up_interruptible(&wq->queue);
53 fput(sbi->pipe); /* Close the pipe */
56 mutex_unlock(&sbi->wq_mutex);
59 static int autofs4_write(struct file *file, const void *addr, int bytes)
61 unsigned long sigpipe, flags;
63 const char *data = (const char *)addr;
66 /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
68 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
70 /* Save pointer to user space and point back to kernel space */
75 (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
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);
88 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
94 static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
95 struct autofs_wait_queue *wq,
99 struct autofs_packet_hdr hdr;
100 union autofs_packet_union v4_pkt;
101 union autofs_v5_packet_union v5_pkt;
103 struct file *pipe = NULL;
106 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
107 (unsigned long) wq->wait_queue_token, wq->name.len, wq->name.name, type);
109 memset(&pkt,0,sizeof pkt); /* For security reasons */
111 pkt.hdr.proto_version = sbi->version;
113 mutex_lock(&sbi->wq_mutex);
115 /* Check if we have become catatonic */
116 if (sbi->catatonic) {
117 mutex_unlock(&sbi->wq_mutex);
121 /* Kernel protocol v4 missing and expire packets */
122 case autofs_ptype_missing:
124 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
128 mp->wait_queue_token = wq->wait_queue_token;
129 mp->len = wq->name.len;
130 memcpy(mp->name, wq->name.name, wq->name.len);
131 mp->name[wq->name.len] = '\0';
134 case autofs_ptype_expire_multi:
136 struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
140 ep->wait_queue_token = wq->wait_queue_token;
141 ep->len = wq->name.len;
142 memcpy(ep->name, wq->name.name, wq->name.len);
143 ep->name[wq->name.len] = '\0';
147 * Kernel protocol v5 packet for handling indirect and direct
148 * mount missing and expire requests
150 case autofs_ptype_missing_indirect:
151 case autofs_ptype_expire_indirect:
152 case autofs_ptype_missing_direct:
153 case autofs_ptype_expire_direct:
155 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
157 pktsz = sizeof(*packet);
159 packet->wait_queue_token = wq->wait_queue_token;
160 packet->len = wq->name.len;
161 memcpy(packet->name, wq->name.name, wq->name.len);
162 packet->name[wq->name.len] = '\0';
163 packet->dev = wq->dev;
164 packet->ino = wq->ino;
165 packet->uid = wq->uid;
166 packet->gid = wq->gid;
167 packet->pid = wq->pid;
168 packet->tgid = wq->tgid;
172 printk("autofs4_notify_daemon: bad type %d!\n", type);
173 mutex_unlock(&sbi->wq_mutex);
180 mutex_unlock(&sbi->wq_mutex);
182 if (autofs4_write(pipe, &pkt, pktsz))
183 autofs4_catatonic_mode(sbi);
187 static int autofs4_getpath(struct autofs_sb_info *sbi,
188 struct dentry *dentry, char **name)
190 struct dentry *root = sbi->sb->s_root;
201 seq = read_seqbegin(&rename_lock);
203 spin_lock(&sbi->fs_lock);
204 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
205 len += tmp->d_name.len + 1;
207 if (!len || --len > NAME_MAX) {
208 spin_unlock(&sbi->fs_lock);
210 if (read_seqretry(&rename_lock, seq))
216 p = buf + len - dentry->d_name.len;
217 strncpy(p, dentry->d_name.name, dentry->d_name.len);
219 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
221 p -= tmp->d_name.len;
222 strncpy(p, tmp->d_name.name, tmp->d_name.len);
224 spin_unlock(&sbi->fs_lock);
226 if (read_seqretry(&rename_lock, seq))
232 static struct autofs_wait_queue *
233 autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
235 struct autofs_wait_queue *wq;
237 for (wq = sbi->queues; wq; wq = wq->next) {
238 if (wq->name.hash == qstr->hash &&
239 wq->name.len == qstr->len &&
241 !memcmp(wq->name.name, qstr->name, qstr->len))
248 * Check if we have a valid request.
250 * 1 if the request should continue.
251 * In this case we can return an autofs_wait_queue entry if one is
252 * found or NULL to idicate a new wait needs to be created.
253 * 0 or a negative errno if the request shouldn't continue.
255 static int validate_request(struct autofs_wait_queue **wait,
256 struct autofs_sb_info *sbi,
258 struct dentry*dentry, enum autofs_notify notify)
260 struct autofs_wait_queue *wq;
261 struct autofs_info *ino;
263 /* Wait in progress, continue; */
264 wq = autofs4_find_wait(sbi, qstr);
272 /* If we don't yet have any info this is a new request */
273 ino = autofs4_dentry_ino(dentry);
278 * If we've been asked to wait on an existing expire (NFY_NONE)
279 * but there is no wait in the queue ...
281 if (notify == NFY_NONE) {
283 * Either we've betean the pending expire to post it's
284 * wait or it finished while we waited on the mutex.
285 * So we need to wait till either, the wait appears
286 * or the expire finishes.
289 while (ino->flags & AUTOFS_INF_EXPIRING) {
290 mutex_unlock(&sbi->wq_mutex);
291 schedule_timeout_interruptible(HZ/10);
292 if (mutex_lock_interruptible(&sbi->wq_mutex))
295 wq = autofs4_find_wait(sbi, qstr);
303 * Not ideal but the status has already gone. Of the two
304 * cases where we wait on NFY_NONE neither depend on the
305 * return status of the wait.
311 * If we've been asked to trigger a mount and the request
312 * completed while we waited on the mutex ...
314 if (notify == NFY_MOUNT) {
315 struct dentry *new = NULL;
319 * If the dentry was successfully mounted while we slept
320 * on the wait queue mutex we can return success. If it
321 * isn't mounted (doesn't have submounts for the case of
322 * a multi-mount with no mount at it's base) we can
323 * continue on and create a new request.
325 if (!IS_ROOT(dentry)) {
326 if (dentry->d_inode && d_unhashed(dentry)) {
327 struct dentry *parent = dentry->d_parent;
328 new = d_lookup(parent, &dentry->d_name);
333 if (have_submounts(dentry))
344 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
345 enum autofs_notify notify)
347 struct autofs_wait_queue *wq;
350 int status, ret, type;
352 /* In catatonic mode, we don't wait for nobody */
356 if (!dentry->d_inode) {
358 * A wait for a negative dentry is invalid for certain
359 * cases. A direct or offset mount "always" has its mount
360 * point directory created and so the request dentry must
361 * be positive or the map key doesn't exist. The situation
362 * is very similar for indirect mounts except only dentrys
363 * in the root of the autofs file system may be negative.
365 if (autofs_type_trigger(sbi->type))
367 else if (!IS_ROOT(dentry->d_parent))
371 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
375 /* If this is a direct mount request create a dummy name */
376 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
377 qstr.len = sprintf(name, "%p", dentry);
379 qstr.len = autofs4_getpath(sbi, dentry, &name);
386 qstr.hash = full_name_hash(name, qstr.len);
388 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
393 ret = validate_request(&wq, sbi, &qstr, dentry, notify);
396 mutex_unlock(&sbi->wq_mutex);
402 /* Create a new wait queue */
403 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
406 mutex_unlock(&sbi->wq_mutex);
410 wq->wait_queue_token = autofs4_next_wait_queue;
411 if (++autofs4_next_wait_queue == 0)
412 autofs4_next_wait_queue = 1;
413 wq->next = sbi->queues;
415 init_waitqueue_head(&wq->queue);
416 memcpy(&wq->name, &qstr, sizeof(struct qstr));
417 wq->dev = autofs4_get_dev(sbi);
418 wq->ino = autofs4_get_ino(sbi);
419 wq->uid = current_uid();
420 wq->gid = current_gid();
421 wq->pid = current->pid;
422 wq->tgid = current->tgid;
423 wq->status = -EINTR; /* Status return if interrupted */
425 mutex_unlock(&sbi->wq_mutex);
427 if (sbi->version < 5) {
428 if (notify == NFY_MOUNT)
429 type = autofs_ptype_missing;
431 type = autofs_ptype_expire_multi;
433 if (notify == NFY_MOUNT)
434 type = autofs_type_trigger(sbi->type) ?
435 autofs_ptype_missing_direct :
436 autofs_ptype_missing_indirect;
438 type = autofs_type_trigger(sbi->type) ?
439 autofs_ptype_expire_direct :
440 autofs_ptype_expire_indirect;
443 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
444 (unsigned long) wq->wait_queue_token, wq->name.len,
445 wq->name.name, notify);
447 /* autofs4_notify_daemon() may block */
448 autofs4_notify_daemon(sbi, wq, type);
451 mutex_unlock(&sbi->wq_mutex);
453 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
454 (unsigned long) wq->wait_queue_token, wq->name.len,
455 wq->name.name, notify);
459 * wq->name.name is NULL iff the lock is already released
460 * or the mount has been made catatonic.
463 /* Block all but "shutdown" signals while waiting */
465 unsigned long irqflags;
467 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
468 oldset = current->blocked;
469 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
471 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
473 wait_event_interruptible(wq->queue, wq->name.name == NULL);
475 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
476 current->blocked = oldset;
478 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
480 DPRINTK("skipped sleeping");
486 * For direct and offset mounts we need to track the requester's
487 * uid and gid in the dentry info struct. This is so it can be
488 * supplied, on request, by the misc device ioctl interface.
489 * This is needed during daemon resatart when reconnecting
490 * to existing, active, autofs mounts. The uid and gid (and
491 * related string values) may be used for macro substitution
492 * in autofs mount maps.
495 struct autofs_info *ino;
496 struct dentry *de = NULL;
498 /* direct mount or browsable map */
499 ino = autofs4_dentry_ino(dentry);
501 /* If not lookup actual dentry used */
502 de = d_lookup(dentry->d_parent, &dentry->d_name);
504 ino = autofs4_dentry_ino(de);
507 /* Set mount requester */
509 spin_lock(&sbi->fs_lock);
512 spin_unlock(&sbi->fs_lock);
519 /* Are we the last process to need status? */
520 mutex_lock(&sbi->wq_mutex);
523 mutex_unlock(&sbi->wq_mutex);
529 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
531 struct autofs_wait_queue *wq, **wql;
533 mutex_lock(&sbi->wq_mutex);
534 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
535 if (wq->wait_queue_token == wait_queue_token)
540 mutex_unlock(&sbi->wq_mutex);
544 *wql = wq->next; /* Unlink from chain */
545 kfree(wq->name.name);
546 wq->name.name = NULL; /* Do not wait on this queue */
548 wake_up_interruptible(&wq->queue);
551 mutex_unlock(&sbi->wq_mutex);