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 */
48 wake_up_interruptible(&wq->queue);
51 fput(sbi->pipe); /* Close the pipe */
54 mutex_unlock(&sbi->wq_mutex);
57 static int autofs4_write(struct autofs_sb_info *sbi,
58 struct file *file, const void *addr, int bytes)
60 unsigned long sigpipe, flags;
62 const char *data = (const char *)addr;
65 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
67 /* Save pointer to user space and point back to kernel space */
71 mutex_lock(&sbi->pipe_mutex);
73 (wr = __vfs_write(file,data,bytes,&file->f_pos)) > 0) {
77 mutex_unlock(&sbi->pipe_mutex);
81 /* Keep the currently executing process from receiving a
82 SIGPIPE unless it was already supposed to get one */
83 if (wr == -EPIPE && !sigpipe) {
84 spin_lock_irqsave(¤t->sighand->siglock, flags);
85 sigdelset(¤t->pending.signal, SIGPIPE);
87 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
90 /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
91 return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
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;
107 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
108 (unsigned long) wq->wait_queue_token, wq->name.len, wq->name.name, type);
110 memset(&pkt,0,sizeof pkt); /* For security reasons */
112 pkt.hdr.proto_version = sbi->version;
116 /* Kernel protocol v4 missing and expire packets */
117 case autofs_ptype_missing:
119 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
123 mp->wait_queue_token = wq->wait_queue_token;
124 mp->len = wq->name.len;
125 memcpy(mp->name, wq->name.name, wq->name.len);
126 mp->name[wq->name.len] = '\0';
129 case autofs_ptype_expire_multi:
131 struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
135 ep->wait_queue_token = wq->wait_queue_token;
136 ep->len = wq->name.len;
137 memcpy(ep->name, wq->name.name, wq->name.len);
138 ep->name[wq->name.len] = '\0';
142 * Kernel protocol v5 packet for handling indirect and direct
143 * mount missing and expire requests
145 case autofs_ptype_missing_indirect:
146 case autofs_ptype_expire_indirect:
147 case autofs_ptype_missing_direct:
148 case autofs_ptype_expire_direct:
150 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
151 struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
153 pktsz = sizeof(*packet);
155 packet->wait_queue_token = wq->wait_queue_token;
156 packet->len = wq->name.len;
157 memcpy(packet->name, wq->name.name, wq->name.len);
158 packet->name[wq->name.len] = '\0';
159 packet->dev = wq->dev;
160 packet->ino = wq->ino;
161 packet->uid = from_kuid_munged(user_ns, wq->uid);
162 packet->gid = from_kgid_munged(user_ns, wq->gid);
163 packet->pid = wq->pid;
164 packet->tgid = wq->tgid;
168 printk("autofs4_notify_daemon: bad type %d!\n", type);
169 mutex_unlock(&sbi->wq_mutex);
173 pipe = get_file(sbi->pipe);
175 mutex_unlock(&sbi->wq_mutex);
177 switch (ret = autofs4_write(sbi, pipe, &pkt, pktsz)) {
182 /* Just fail this one */
183 autofs4_wait_release(sbi, wq->wait_queue_token, ret);
186 autofs4_catatonic_mode(sbi);
192 static int autofs4_getpath(struct autofs_sb_info *sbi,
193 struct dentry *dentry, char **name)
195 struct dentry *root = sbi->sb->s_root;
206 seq = read_seqbegin(&rename_lock);
208 spin_lock(&sbi->fs_lock);
209 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
210 len += tmp->d_name.len + 1;
212 if (!len || --len > NAME_MAX) {
213 spin_unlock(&sbi->fs_lock);
215 if (read_seqretry(&rename_lock, seq))
221 p = buf + len - dentry->d_name.len;
222 strncpy(p, dentry->d_name.name, dentry->d_name.len);
224 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
226 p -= tmp->d_name.len;
227 strncpy(p, tmp->d_name.name, tmp->d_name.len);
229 spin_unlock(&sbi->fs_lock);
231 if (read_seqretry(&rename_lock, seq))
237 static struct autofs_wait_queue *
238 autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
240 struct autofs_wait_queue *wq;
242 for (wq = sbi->queues; wq; wq = wq->next) {
243 if (wq->name.hash == qstr->hash &&
244 wq->name.len == qstr->len &&
246 !memcmp(wq->name.name, qstr->name, qstr->len))
253 * Check if we have a valid request.
255 * 1 if the request should continue.
256 * In this case we can return an autofs_wait_queue entry if one is
257 * found or NULL to idicate a new wait needs to be created.
258 * 0 or a negative errno if the request shouldn't continue.
260 static int validate_request(struct autofs_wait_queue **wait,
261 struct autofs_sb_info *sbi,
263 struct dentry*dentry, enum autofs_notify notify)
265 struct autofs_wait_queue *wq;
266 struct autofs_info *ino;
271 /* Wait in progress, continue; */
272 wq = autofs4_find_wait(sbi, qstr);
280 /* If we don't yet have any info this is a new request */
281 ino = autofs4_dentry_ino(dentry);
286 * If we've been asked to wait on an existing expire (NFY_NONE)
287 * but there is no wait in the queue ...
289 if (notify == NFY_NONE) {
291 * Either we've betean the pending expire to post it's
292 * wait or it finished while we waited on the mutex.
293 * So we need to wait till either, the wait appears
294 * or the expire finishes.
297 while (ino->flags & AUTOFS_INF_EXPIRING) {
298 mutex_unlock(&sbi->wq_mutex);
299 schedule_timeout_interruptible(HZ/10);
300 if (mutex_lock_interruptible(&sbi->wq_mutex))
306 wq = autofs4_find_wait(sbi, qstr);
314 * Not ideal but the status has already gone. Of the two
315 * cases where we wait on NFY_NONE neither depend on the
316 * return status of the wait.
322 * If we've been asked to trigger a mount and the request
323 * completed while we waited on the mutex ...
325 if (notify == NFY_MOUNT) {
326 struct dentry *new = NULL;
330 * If the dentry was successfully mounted while we slept
331 * on the wait queue mutex we can return success. If it
332 * isn't mounted (doesn't have submounts for the case of
333 * a multi-mount with no mount at it's base) we can
334 * continue on and create a new request.
336 if (!IS_ROOT(dentry)) {
337 if (d_really_is_positive(dentry) && d_unhashed(dentry)) {
338 struct dentry *parent = dentry->d_parent;
339 new = d_lookup(parent, &dentry->d_name);
344 if (have_submounts(dentry))
355 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
356 enum autofs_notify notify)
358 struct autofs_wait_queue *wq;
361 int status, ret, type;
365 /* In catatonic mode, we don't wait for nobody */
370 * Try translating pids to the namespace of the daemon.
372 * Zero means failure: we are in an unrelated pid namespace.
374 pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
375 tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
376 if (pid == 0 || tgid == 0)
379 if (d_really_is_negative(dentry)) {
381 * A wait for a negative dentry is invalid for certain
382 * cases. A direct or offset mount "always" has its mount
383 * point directory created and so the request dentry must
384 * be positive or the map key doesn't exist. The situation
385 * is very similar for indirect mounts except only dentrys
386 * in the root of the autofs file system may be negative.
388 if (autofs_type_trigger(sbi->type))
390 else if (!IS_ROOT(dentry->d_parent))
394 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
398 /* If this is a direct mount request create a dummy name */
399 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
400 qstr.len = sprintf(name, "%p", dentry);
402 qstr.len = autofs4_getpath(sbi, dentry, &name);
409 qstr.hash = full_name_hash(name, qstr.len);
411 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
416 ret = validate_request(&wq, sbi, &qstr, dentry, notify);
419 mutex_unlock(&sbi->wq_mutex);
425 /* Create a new wait queue */
426 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
429 mutex_unlock(&sbi->wq_mutex);
433 wq->wait_queue_token = autofs4_next_wait_queue;
434 if (++autofs4_next_wait_queue == 0)
435 autofs4_next_wait_queue = 1;
436 wq->next = sbi->queues;
438 init_waitqueue_head(&wq->queue);
439 memcpy(&wq->name, &qstr, sizeof(struct qstr));
440 wq->dev = autofs4_get_dev(sbi);
441 wq->ino = autofs4_get_ino(sbi);
442 wq->uid = current_uid();
443 wq->gid = current_gid();
446 wq->status = -EINTR; /* Status return if interrupted */
449 if (sbi->version < 5) {
450 if (notify == NFY_MOUNT)
451 type = autofs_ptype_missing;
453 type = autofs_ptype_expire_multi;
455 if (notify == NFY_MOUNT)
456 type = autofs_type_trigger(sbi->type) ?
457 autofs_ptype_missing_direct :
458 autofs_ptype_missing_indirect;
460 type = autofs_type_trigger(sbi->type) ?
461 autofs_ptype_expire_direct :
462 autofs_ptype_expire_indirect;
465 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
466 (unsigned long) wq->wait_queue_token, wq->name.len,
467 wq->name.name, notify);
469 /* autofs4_notify_daemon() may block; it will unlock ->wq_mutex */
470 autofs4_notify_daemon(sbi, wq, type);
473 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
474 (unsigned long) wq->wait_queue_token, wq->name.len,
475 wq->name.name, notify);
476 mutex_unlock(&sbi->wq_mutex);
481 * wq->name.name is NULL iff the lock is already released
482 * or the mount has been made catatonic.
485 /* Block all but "shutdown" signals while waiting */
487 unsigned long irqflags;
489 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
490 oldset = current->blocked;
491 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
493 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
495 wait_event_interruptible(wq->queue, wq->name.name == NULL);
497 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
498 current->blocked = oldset;
500 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
502 DPRINTK("skipped sleeping");
508 * For direct and offset mounts we need to track the requester's
509 * uid and gid in the dentry info struct. This is so it can be
510 * supplied, on request, by the misc device ioctl interface.
511 * This is needed during daemon resatart when reconnecting
512 * to existing, active, autofs mounts. The uid and gid (and
513 * related string values) may be used for macro substitution
514 * in autofs mount maps.
517 struct autofs_info *ino;
518 struct dentry *de = NULL;
520 /* direct mount or browsable map */
521 ino = autofs4_dentry_ino(dentry);
523 /* If not lookup actual dentry used */
524 de = d_lookup(dentry->d_parent, &dentry->d_name);
526 ino = autofs4_dentry_ino(de);
529 /* Set mount requester */
531 spin_lock(&sbi->fs_lock);
534 spin_unlock(&sbi->fs_lock);
541 /* Are we the last process to need status? */
542 mutex_lock(&sbi->wq_mutex);
545 mutex_unlock(&sbi->wq_mutex);
551 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
553 struct autofs_wait_queue *wq, **wql;
555 mutex_lock(&sbi->wq_mutex);
556 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
557 if (wq->wait_queue_token == wait_queue_token)
562 mutex_unlock(&sbi->wq_mutex);
566 *wql = wq->next; /* Unlink from chain */
567 kfree(wq->name.name);
568 wq->name.name = NULL; /* Do not wait on this queue */
570 wake_up_interruptible(&wq->queue);
573 mutex_unlock(&sbi->wq_mutex);