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 DPRINTK("entering catatonic mode");
35 sbi->queues = NULL; /* Erase all wait queues */
38 wq->status = -ENOENT; /* Magic is gone - report failure */
41 wake_up_interruptible(&wq->queue);
44 fput(sbi->pipe); /* Close the pipe */
48 static int autofs4_write(struct file *file, const void *addr, int bytes)
50 unsigned long sigpipe, flags;
52 const char *data = (const char *)addr;
55 /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
57 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
59 /* Save pointer to user space and point back to kernel space */
64 (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
71 /* Keep the currently executing process from receiving a
72 SIGPIPE unless it was already supposed to get one */
73 if (wr == -EPIPE && !sigpipe) {
74 spin_lock_irqsave(¤t->sighand->siglock, flags);
75 sigdelset(¤t->pending.signal, SIGPIPE);
77 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
83 static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
84 struct autofs_wait_queue *wq,
87 union autofs_packet_union pkt;
90 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
91 wq->wait_queue_token, wq->len, wq->name, type);
93 memset(&pkt,0,sizeof pkt); /* For security reasons */
95 pkt.hdr.proto_version = sbi->version;
98 /* Kernel protocol v4 missing and expire packets */
99 case autofs_ptype_missing:
101 struct autofs_packet_missing *mp = &pkt.missing;
105 mp->wait_queue_token = wq->wait_queue_token;
107 memcpy(mp->name, wq->name, wq->len);
108 mp->name[wq->len] = '\0';
111 case autofs_ptype_expire_multi:
113 struct autofs_packet_expire_multi *ep = &pkt.expire_multi;
117 ep->wait_queue_token = wq->wait_queue_token;
119 memcpy(ep->name, wq->name, wq->len);
120 ep->name[wq->len] = '\0';
124 * Kernel protocol v5 packet for handling indirect and direct
125 * mount missing and expire requests
127 case autofs_ptype_missing_indirect:
128 case autofs_ptype_expire_indirect:
129 case autofs_ptype_missing_direct:
130 case autofs_ptype_expire_direct:
132 struct autofs_v5_packet *packet = &pkt.v5_packet;
134 pktsz = sizeof(*packet);
136 packet->wait_queue_token = wq->wait_queue_token;
137 packet->len = wq->len;
138 memcpy(packet->name, wq->name, wq->len);
139 packet->name[wq->len] = '\0';
140 packet->dev = wq->dev;
141 packet->ino = wq->ino;
142 packet->uid = wq->uid;
143 packet->gid = wq->gid;
144 packet->pid = wq->pid;
145 packet->tgid = wq->tgid;
149 printk("autofs4_notify_daemon: bad type %d!\n", type);
153 if (autofs4_write(sbi->pipe, &pkt, pktsz))
154 autofs4_catatonic_mode(sbi);
157 static int autofs4_getpath(struct autofs_sb_info *sbi,
158 struct dentry *dentry, char **name)
160 struct dentry *root = sbi->sb->s_root;
166 spin_lock(&dcache_lock);
167 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
168 len += tmp->d_name.len + 1;
170 if (--len > NAME_MAX) {
171 spin_unlock(&dcache_lock);
176 p = buf + len - dentry->d_name.len;
177 strncpy(p, dentry->d_name.name, dentry->d_name.len);
179 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
181 p -= tmp->d_name.len;
182 strncpy(p, tmp->d_name.name, tmp->d_name.len);
184 spin_unlock(&dcache_lock);
189 static struct autofs_wait_queue *
190 autofs4_find_wait(struct autofs_sb_info *sbi,
191 char *name, unsigned int hash, unsigned int len)
193 struct autofs_wait_queue *wq;
195 for (wq = sbi->queues; wq; wq = wq->next) {
196 if (wq->hash == hash &&
198 wq->name && !memcmp(wq->name, name, len))
204 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
205 enum autofs_notify notify)
207 struct autofs_info *ino;
208 struct autofs_wait_queue *wq;
210 unsigned int len = 0;
211 unsigned int hash = 0;
214 /* In catatonic mode, we don't wait for nobody */
218 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
222 /* If this is a direct mount request create a dummy name */
223 if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))
224 len = sprintf(name, "%p", dentry);
226 len = autofs4_getpath(sbi, dentry, &name);
232 hash = full_name_hash(name, len);
234 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
239 wq = autofs4_find_wait(sbi, name, hash, len);
240 ino = autofs4_dentry_ino(dentry);
241 if (!wq && ino && notify == NFY_NONE) {
243 * Either we've betean the pending expire to post it's
244 * wait or it finished while we waited on the mutex.
245 * So we need to wait till either, the wait appears
246 * or the expire finishes.
249 while (ino->flags & AUTOFS_INF_EXPIRING) {
250 mutex_unlock(&sbi->wq_mutex);
251 schedule_timeout_interruptible(HZ/10);
252 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
256 wq = autofs4_find_wait(sbi, name, hash, len);
262 * Not ideal but the status has already gone. Of the two
263 * cases where we wait on NFY_NONE neither depend on the
264 * return status of the wait.
268 mutex_unlock(&sbi->wq_mutex);
274 /* Create a new wait queue */
275 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
278 mutex_unlock(&sbi->wq_mutex);
282 wq->wait_queue_token = autofs4_next_wait_queue;
283 if (++autofs4_next_wait_queue == 0)
284 autofs4_next_wait_queue = 1;
285 wq->next = sbi->queues;
287 init_waitqueue_head(&wq->queue);
291 wq->dev = autofs4_get_dev(sbi);
292 wq->ino = autofs4_get_ino(sbi);
293 wq->uid = current->uid;
294 wq->gid = current->gid;
295 wq->pid = current->pid;
296 wq->tgid = current->tgid;
297 wq->status = -EINTR; /* Status return if interrupted */
298 atomic_set(&wq->wait_ctr, 2);
299 mutex_unlock(&sbi->wq_mutex);
301 if (sbi->version < 5) {
302 if (notify == NFY_MOUNT)
303 type = autofs_ptype_missing;
305 type = autofs_ptype_expire_multi;
307 if (notify == NFY_MOUNT)
308 type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
309 autofs_ptype_missing_direct :
310 autofs_ptype_missing_indirect;
312 type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
313 autofs_ptype_expire_direct :
314 autofs_ptype_expire_indirect;
317 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
318 (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
320 /* autofs4_notify_daemon() may block */
321 autofs4_notify_daemon(sbi, wq, type);
323 atomic_inc(&wq->wait_ctr);
324 mutex_unlock(&sbi->wq_mutex);
326 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
327 (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
330 /* wq->name is NULL if and only if the lock is already released */
332 if (sbi->catatonic) {
333 /* We might have slept, so check again for catatonic mode */
334 wq->status = -ENOENT;
340 /* Block all but "shutdown" signals while waiting */
342 unsigned long irqflags;
344 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
345 oldset = current->blocked;
346 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
348 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
350 wait_event_interruptible(wq->queue, wq->name == NULL);
352 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
353 current->blocked = oldset;
355 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
357 DPRINTK("skipped sleeping");
362 /* Are we the last process to need status? */
363 if (atomic_dec_and_test(&wq->wait_ctr))
370 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
372 struct autofs_wait_queue *wq, **wql;
374 mutex_lock(&sbi->wq_mutex);
375 for (wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next) {
376 if (wq->wait_queue_token == wait_queue_token)
381 mutex_unlock(&sbi->wq_mutex);
385 *wql = wq->next; /* Unlink from chain */
386 mutex_unlock(&sbi->wq_mutex);
388 wq->name = NULL; /* Do not wait on this queue */
392 if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */
395 wake_up_interruptible(&wq->queue);