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;
104 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
105 wq->wait_queue_token, wq->name.len, wq->name.name, type);
107 memset(&pkt,0,sizeof pkt); /* For security reasons */
109 pkt.hdr.proto_version = sbi->version;
112 /* Kernel protocol v4 missing and expire packets */
113 case autofs_ptype_missing:
115 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
119 mp->wait_queue_token = wq->wait_queue_token;
120 mp->len = wq->name.len;
121 memcpy(mp->name, wq->name.name, wq->name.len);
122 mp->name[wq->name.len] = '\0';
125 case autofs_ptype_expire_multi:
127 struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
131 ep->wait_queue_token = wq->wait_queue_token;
132 ep->len = wq->name.len;
133 memcpy(ep->name, wq->name.name, wq->name.len);
134 ep->name[wq->name.len] = '\0';
138 * Kernel protocol v5 packet for handling indirect and direct
139 * mount missing and expire requests
141 case autofs_ptype_missing_indirect:
142 case autofs_ptype_expire_indirect:
143 case autofs_ptype_missing_direct:
144 case autofs_ptype_expire_direct:
146 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
148 pktsz = sizeof(*packet);
150 packet->wait_queue_token = wq->wait_queue_token;
151 packet->len = wq->name.len;
152 memcpy(packet->name, wq->name.name, wq->name.len);
153 packet->name[wq->name.len] = '\0';
154 packet->dev = wq->dev;
155 packet->ino = wq->ino;
156 packet->uid = wq->uid;
157 packet->gid = wq->gid;
158 packet->pid = wq->pid;
159 packet->tgid = wq->tgid;
163 printk("autofs4_notify_daemon: bad type %d!\n", type);
167 if (autofs4_write(sbi->pipe, &pkt, pktsz))
168 autofs4_catatonic_mode(sbi);
171 static int autofs4_getpath(struct autofs_sb_info *sbi,
172 struct dentry *dentry, char **name)
174 struct dentry *root = sbi->sb->s_root;
180 spin_lock(&dcache_lock);
181 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
182 len += tmp->d_name.len + 1;
184 if (!len || --len > NAME_MAX) {
185 spin_unlock(&dcache_lock);
190 p = buf + len - dentry->d_name.len;
191 strncpy(p, dentry->d_name.name, dentry->d_name.len);
193 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
195 p -= tmp->d_name.len;
196 strncpy(p, tmp->d_name.name, tmp->d_name.len);
198 spin_unlock(&dcache_lock);
203 static struct autofs_wait_queue *
204 autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
206 struct autofs_wait_queue *wq;
208 for (wq = sbi->queues; wq; wq = wq->next) {
209 if (wq->name.hash == qstr->hash &&
210 wq->name.len == qstr->len &&
212 !memcmp(wq->name.name, qstr->name, qstr->len))
218 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
219 enum autofs_notify notify)
221 struct autofs_info *ino;
222 struct autofs_wait_queue *wq;
227 /* In catatonic mode, we don't wait for nobody */
231 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
235 /* If this is a direct mount request create a dummy name */
236 if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))
237 qstr.len = sprintf(name, "%p", dentry);
239 qstr.len = autofs4_getpath(sbi, dentry, &name);
246 qstr.hash = full_name_hash(name, qstr.len);
248 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
253 wq = autofs4_find_wait(sbi, &qstr);
254 ino = autofs4_dentry_ino(dentry);
255 if (!wq && ino && notify == NFY_NONE) {
257 * Either we've betean the pending expire to post it's
258 * wait or it finished while we waited on the mutex.
259 * So we need to wait till either, the wait appears
260 * or the expire finishes.
263 while (ino->flags & AUTOFS_INF_EXPIRING) {
264 mutex_unlock(&sbi->wq_mutex);
265 schedule_timeout_interruptible(HZ/10);
266 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
270 wq = autofs4_find_wait(sbi, &qstr);
276 * Not ideal but the status has already gone. Of the two
277 * cases where we wait on NFY_NONE neither depend on the
278 * return status of the wait.
282 mutex_unlock(&sbi->wq_mutex);
288 /* Create a new wait queue */
289 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
292 mutex_unlock(&sbi->wq_mutex);
296 wq->wait_queue_token = autofs4_next_wait_queue;
297 if (++autofs4_next_wait_queue == 0)
298 autofs4_next_wait_queue = 1;
299 wq->next = sbi->queues;
301 init_waitqueue_head(&wq->queue);
302 memcpy(&wq->name, &qstr, sizeof(struct qstr));
303 wq->dev = autofs4_get_dev(sbi);
304 wq->ino = autofs4_get_ino(sbi);
305 wq->uid = current->uid;
306 wq->gid = current->gid;
307 wq->pid = current->pid;
308 wq->tgid = current->tgid;
309 wq->status = -EINTR; /* Status return if interrupted */
310 atomic_set(&wq->wait_ctr, 2);
311 mutex_unlock(&sbi->wq_mutex);
313 if (sbi->version < 5) {
314 if (notify == NFY_MOUNT)
315 type = autofs_ptype_missing;
317 type = autofs_ptype_expire_multi;
319 if (notify == NFY_MOUNT)
320 type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
321 autofs_ptype_missing_direct :
322 autofs_ptype_missing_indirect;
324 type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
325 autofs_ptype_expire_direct :
326 autofs_ptype_expire_indirect;
329 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
330 (unsigned long) wq->wait_queue_token, wq->name.len,
331 wq->name.name, notify);
333 /* autofs4_notify_daemon() may block */
334 autofs4_notify_daemon(sbi, wq, type);
336 atomic_inc(&wq->wait_ctr);
337 mutex_unlock(&sbi->wq_mutex);
339 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
340 (unsigned long) wq->wait_queue_token, wq->name.len,
341 wq->name.name, notify);
345 * wq->name.name is NULL iff the lock is already released
346 * or the mount has been made catatonic.
349 /* Block all but "shutdown" signals while waiting */
351 unsigned long irqflags;
353 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
354 oldset = current->blocked;
355 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
357 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
359 wait_event_interruptible(wq->queue, wq->name.name == NULL);
361 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
362 current->blocked = oldset;
364 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
366 DPRINTK("skipped sleeping");
371 /* Are we the last process to need status? */
372 if (atomic_dec_and_test(&wq->wait_ctr))
379 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
381 struct autofs_wait_queue *wq, **wql;
383 mutex_lock(&sbi->wq_mutex);
384 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
385 if (wq->wait_queue_token == wait_queue_token)
390 mutex_unlock(&sbi->wq_mutex);
394 *wql = wq->next; /* Unlink from chain */
395 mutex_unlock(&sbi->wq_mutex);
396 kfree(wq->name.name);
397 wq->name.name = NULL; /* Do not wait on this queue */
401 if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */
404 wake_up_interruptible(&wq->queue);