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 */
49 wake_up_interruptible(&wq->queue);
52 fput(sbi->pipe); /* Close the pipe */
55 mutex_unlock(&sbi->wq_mutex);
58 static int autofs4_write(struct file *file, const void *addr, int bytes)
60 unsigned long sigpipe, flags;
62 const char *data = (const char *)addr;
65 /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
67 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
69 /* Save pointer to user space and point back to kernel space */
74 (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
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);
93 static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
94 struct autofs_wait_queue *wq,
98 struct autofs_packet_hdr hdr;
99 union autofs_packet_union v4_pkt;
100 union autofs_v5_packet_union v5_pkt;
102 struct file *pipe = NULL;
105 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
106 wq->wait_queue_token, wq->name.len, wq->name.name, type);
108 memset(&pkt,0,sizeof pkt); /* For security reasons */
110 pkt.hdr.proto_version = sbi->version;
113 /* Kernel protocol v4 missing and expire packets */
114 case autofs_ptype_missing:
116 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
120 mp->wait_queue_token = wq->wait_queue_token;
121 mp->len = wq->name.len;
122 memcpy(mp->name, wq->name.name, wq->name.len);
123 mp->name[wq->name.len] = '\0';
126 case autofs_ptype_expire_multi:
128 struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
132 ep->wait_queue_token = wq->wait_queue_token;
133 ep->len = wq->name.len;
134 memcpy(ep->name, wq->name.name, wq->name.len);
135 ep->name[wq->name.len] = '\0';
139 * Kernel protocol v5 packet for handling indirect and direct
140 * mount missing and expire requests
142 case autofs_ptype_missing_indirect:
143 case autofs_ptype_expire_indirect:
144 case autofs_ptype_missing_direct:
145 case autofs_ptype_expire_direct:
147 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
149 pktsz = sizeof(*packet);
151 packet->wait_queue_token = wq->wait_queue_token;
152 packet->len = wq->name.len;
153 memcpy(packet->name, wq->name.name, wq->name.len);
154 packet->name[wq->name.len] = '\0';
155 packet->dev = wq->dev;
156 packet->ino = wq->ino;
157 packet->uid = wq->uid;
158 packet->gid = wq->gid;
159 packet->pid = wq->pid;
160 packet->tgid = wq->tgid;
164 printk("autofs4_notify_daemon: bad type %d!\n", type);
168 /* Check if we have become catatonic */
169 mutex_lock(&sbi->wq_mutex);
170 if (!sbi->catatonic) {
174 mutex_unlock(&sbi->wq_mutex);
177 if (autofs4_write(pipe, &pkt, pktsz))
178 autofs4_catatonic_mode(sbi);
183 static int autofs4_getpath(struct autofs_sb_info *sbi,
184 struct dentry *dentry, char **name)
186 struct dentry *root = sbi->sb->s_root;
192 spin_lock(&dcache_lock);
193 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
194 len += tmp->d_name.len + 1;
196 if (!len || --len > NAME_MAX) {
197 spin_unlock(&dcache_lock);
202 p = buf + len - dentry->d_name.len;
203 strncpy(p, dentry->d_name.name, dentry->d_name.len);
205 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
207 p -= tmp->d_name.len;
208 strncpy(p, tmp->d_name.name, tmp->d_name.len);
210 spin_unlock(&dcache_lock);
215 static struct autofs_wait_queue *
216 autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
218 struct autofs_wait_queue *wq;
220 for (wq = sbi->queues; wq; wq = wq->next) {
221 if (wq->name.hash == qstr->hash &&
222 wq->name.len == qstr->len &&
224 !memcmp(wq->name.name, qstr->name, qstr->len))
231 * Check if we have a valid request.
233 * 1 if the request should continue.
234 * In this case we can return an autofs_wait_queue entry if one is
235 * found or NULL to idicate a new wait needs to be created.
236 * 0 or a negative errno if the request shouldn't continue.
238 static int validate_request(struct autofs_wait_queue **wait,
239 struct autofs_sb_info *sbi,
241 struct dentry*dentry, enum autofs_notify notify)
243 struct autofs_wait_queue *wq;
244 struct autofs_info *ino;
246 /* Wait in progress, continue; */
247 wq = autofs4_find_wait(sbi, qstr);
255 /* If we don't yet have any info this is a new request */
256 ino = autofs4_dentry_ino(dentry);
261 * If we've been asked to wait on an existing expire (NFY_NONE)
262 * but there is no wait in the queue ...
264 if (notify == NFY_NONE) {
266 * Either we've betean the pending expire to post it's
267 * wait or it finished while we waited on the mutex.
268 * So we need to wait till either, the wait appears
269 * or the expire finishes.
272 while (ino->flags & AUTOFS_INF_EXPIRING) {
273 mutex_unlock(&sbi->wq_mutex);
274 schedule_timeout_interruptible(HZ/10);
275 if (mutex_lock_interruptible(&sbi->wq_mutex))
278 wq = autofs4_find_wait(sbi, qstr);
286 * Not ideal but the status has already gone. Of the two
287 * cases where we wait on NFY_NONE neither depend on the
288 * return status of the wait.
294 * If we've been asked to trigger a mount and the request
295 * completed while we waited on the mutex ...
297 if (notify == NFY_MOUNT) {
299 * If the dentry isn't hashed just go ahead and try the
300 * mount again with a new wait (not much else we can do).
302 if (!d_unhashed(dentry)) {
304 * But if the dentry is hashed, that means that we
305 * got here through the revalidate path. Thus, we
306 * need to check if the dentry has been mounted
307 * while we waited on the wq_mutex. If it has,
308 * simply return success.
310 if (d_mountpoint(dentry))
318 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
319 enum autofs_notify notify)
321 struct autofs_wait_queue *wq;
324 int status, ret, type;
326 /* In catatonic mode, we don't wait for nobody */
330 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
334 /* If this is a direct mount request create a dummy name */
335 if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))
336 qstr.len = sprintf(name, "%p", dentry);
338 qstr.len = autofs4_getpath(sbi, dentry, &name);
345 qstr.hash = full_name_hash(name, qstr.len);
347 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
352 ret = validate_request(&wq, sbi, &qstr, dentry, notify);
355 mutex_unlock(&sbi->wq_mutex);
361 /* Create a new wait queue */
362 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
365 mutex_unlock(&sbi->wq_mutex);
369 wq->wait_queue_token = autofs4_next_wait_queue;
370 if (++autofs4_next_wait_queue == 0)
371 autofs4_next_wait_queue = 1;
372 wq->next = sbi->queues;
374 init_waitqueue_head(&wq->queue);
375 memcpy(&wq->name, &qstr, sizeof(struct qstr));
376 wq->dev = autofs4_get_dev(sbi);
377 wq->ino = autofs4_get_ino(sbi);
378 wq->uid = current->uid;
379 wq->gid = current->gid;
380 wq->pid = current->pid;
381 wq->tgid = current->tgid;
382 wq->status = -EINTR; /* Status return if interrupted */
383 atomic_set(&wq->wait_ctr, 2);
384 mutex_unlock(&sbi->wq_mutex);
386 if (sbi->version < 5) {
387 if (notify == NFY_MOUNT)
388 type = autofs_ptype_missing;
390 type = autofs_ptype_expire_multi;
392 if (notify == NFY_MOUNT)
393 type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
394 autofs_ptype_missing_direct :
395 autofs_ptype_missing_indirect;
397 type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
398 autofs_ptype_expire_direct :
399 autofs_ptype_expire_indirect;
402 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
403 (unsigned long) wq->wait_queue_token, wq->name.len,
404 wq->name.name, notify);
406 /* autofs4_notify_daemon() may block */
407 autofs4_notify_daemon(sbi, wq, type);
409 atomic_inc(&wq->wait_ctr);
410 mutex_unlock(&sbi->wq_mutex);
412 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
413 (unsigned long) wq->wait_queue_token, wq->name.len,
414 wq->name.name, notify);
418 * wq->name.name is NULL iff the lock is already released
419 * or the mount has been made catatonic.
422 /* Block all but "shutdown" signals while waiting */
424 unsigned long irqflags;
426 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
427 oldset = current->blocked;
428 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
430 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
432 wait_event_interruptible(wq->queue, wq->name.name == NULL);
434 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
435 current->blocked = oldset;
437 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
439 DPRINTK("skipped sleeping");
444 /* Are we the last process to need status? */
445 if (atomic_dec_and_test(&wq->wait_ctr))
452 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
454 struct autofs_wait_queue *wq, **wql;
456 mutex_lock(&sbi->wq_mutex);
457 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
458 if (wq->wait_queue_token == wait_queue_token)
463 mutex_unlock(&sbi->wq_mutex);
467 *wql = wq->next; /* Unlink from chain */
468 kfree(wq->name.name);
469 wq->name.name = NULL; /* Do not wait on this queue */
470 mutex_unlock(&sbi->wq_mutex);
474 if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */
477 wake_up_interruptible(&wq->queue);