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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* -*- c -*- --------------------------------------------------------------- *
2 *
3 * linux/fs/autofs/waitq.c
4 *
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
Ian Kent5c0a32f2006-03-27 01:14:55 -08006 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
Linus Torvalds1da177e2005-04-16 15:20:36 -07007 *
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.
11 *
12 * ------------------------------------------------------------------------- */
13
14#include <linux/slab.h>
15#include <linux/time.h>
16#include <linux/signal.h>
17#include <linux/file.h>
18#include "autofs_i.h"
19
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 */
22static autofs_wqt_t autofs4_next_wait_queue = 1;
23
24/* These are the signals we allow interrupting a pending mount */
25#define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
26
27void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
28{
29 struct autofs_wait_queue *wq, *nwq;
30
31 DPRINTK("entering catatonic mode");
32
33 sbi->catatonic = 1;
34 wq = sbi->queues;
35 sbi->queues = NULL; /* Erase all wait queues */
Ian Kente77fbdd2006-03-27 01:14:49 -080036 while (wq) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 nwq = wq->next;
38 wq->status = -ENOENT; /* Magic is gone - report failure */
39 kfree(wq->name);
40 wq->name = NULL;
41 wake_up_interruptible(&wq->queue);
42 wq = nwq;
43 }
Ian Kentba8df432006-11-14 02:03:29 -080044 fput(sbi->pipe); /* Close the pipe */
45 sbi->pipe = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070046}
47
48static int autofs4_write(struct file *file, const void *addr, int bytes)
49{
50 unsigned long sigpipe, flags;
51 mm_segment_t fs;
52 const char *data = (const char *)addr;
53 ssize_t wr = 0;
54
55 /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
56
57 sigpipe = sigismember(&current->pending.signal, SIGPIPE);
58
59 /* Save pointer to user space and point back to kernel space */
60 fs = get_fs();
61 set_fs(KERNEL_DS);
62
63 while (bytes &&
64 (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
65 data += wr;
66 bytes -= wr;
67 }
68
69 set_fs(fs);
70
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(&current->sighand->siglock, flags);
75 sigdelset(&current->pending.signal, SIGPIPE);
76 recalc_sigpending();
77 spin_unlock_irqrestore(&current->sighand->siglock, flags);
78 }
79
80 return (bytes > 0);
81}
82
83static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
84 struct autofs_wait_queue *wq,
85 int type)
86{
Ian Kente8514472007-02-20 13:58:09 -080087 union {
88 struct autofs_packet_hdr hdr;
89 union autofs_packet_union v4_pkt;
90 union autofs_v5_packet_union v5_pkt;
91 } pkt;
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 size_t pktsz;
93
94 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
95 wq->wait_queue_token, wq->len, wq->name, type);
96
97 memset(&pkt,0,sizeof pkt); /* For security reasons */
98
99 pkt.hdr.proto_version = sbi->version;
100 pkt.hdr.type = type;
Ian Kent5c0a32f2006-03-27 01:14:55 -0800101 switch (type) {
102 /* Kernel protocol v4 missing and expire packets */
103 case autofs_ptype_missing:
104 {
Ian Kente8514472007-02-20 13:58:09 -0800105 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
107 pktsz = sizeof(*mp);
108
109 mp->wait_queue_token = wq->wait_queue_token;
110 mp->len = wq->len;
111 memcpy(mp->name, wq->name, wq->len);
112 mp->name[wq->len] = '\0';
Ian Kent5c0a32f2006-03-27 01:14:55 -0800113 break;
114 }
115 case autofs_ptype_expire_multi:
116 {
Ian Kente8514472007-02-20 13:58:09 -0800117 struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118
119 pktsz = sizeof(*ep);
120
121 ep->wait_queue_token = wq->wait_queue_token;
122 ep->len = wq->len;
123 memcpy(ep->name, wq->name, wq->len);
124 ep->name[wq->len] = '\0';
Ian Kent5c0a32f2006-03-27 01:14:55 -0800125 break;
126 }
127 /*
128 * Kernel protocol v5 packet for handling indirect and direct
129 * mount missing and expire requests
130 */
131 case autofs_ptype_missing_indirect:
132 case autofs_ptype_expire_indirect:
133 case autofs_ptype_missing_direct:
134 case autofs_ptype_expire_direct:
135 {
Ian Kente8514472007-02-20 13:58:09 -0800136 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
Ian Kent5c0a32f2006-03-27 01:14:55 -0800137
138 pktsz = sizeof(*packet);
139
140 packet->wait_queue_token = wq->wait_queue_token;
141 packet->len = wq->len;
142 memcpy(packet->name, wq->name, wq->len);
143 packet->name[wq->len] = '\0';
144 packet->dev = wq->dev;
145 packet->ino = wq->ino;
146 packet->uid = wq->uid;
147 packet->gid = wq->gid;
148 packet->pid = wq->pid;
149 packet->tgid = wq->tgid;
150 break;
151 }
152 default:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 printk("autofs4_notify_daemon: bad type %d!\n", type);
154 return;
155 }
156
157 if (autofs4_write(sbi->pipe, &pkt, pktsz))
158 autofs4_catatonic_mode(sbi);
159}
160
161static int autofs4_getpath(struct autofs_sb_info *sbi,
162 struct dentry *dentry, char **name)
163{
164 struct dentry *root = sbi->sb->s_root;
165 struct dentry *tmp;
166 char *buf = *name;
167 char *p;
168 int len = 0;
169
170 spin_lock(&dcache_lock);
171 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
172 len += tmp->d_name.len + 1;
173
174 if (--len > NAME_MAX) {
175 spin_unlock(&dcache_lock);
176 return 0;
177 }
178
179 *(buf + len) = '\0';
180 p = buf + len - dentry->d_name.len;
181 strncpy(p, dentry->d_name.name, dentry->d_name.len);
182
183 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
184 *(--p) = '/';
185 p -= tmp->d_name.len;
186 strncpy(p, tmp->d_name.name, tmp->d_name.len);
187 }
188 spin_unlock(&dcache_lock);
189
190 return len;
191}
192
Ian Kenta5370552006-05-15 09:43:51 -0700193static struct autofs_wait_queue *
194autofs4_find_wait(struct autofs_sb_info *sbi,
195 char *name, unsigned int hash, unsigned int len)
196{
197 struct autofs_wait_queue *wq;
198
199 for (wq = sbi->queues; wq; wq = wq->next) {
200 if (wq->hash == hash &&
201 wq->len == len &&
202 wq->name && !memcmp(wq->name, name, len))
203 break;
204 }
205 return wq;
206}
207
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
209 enum autofs_notify notify)
210{
Ian Kenta5370552006-05-15 09:43:51 -0700211 struct autofs_info *ino;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 struct autofs_wait_queue *wq;
213 char *name;
Ian Kent5c0a32f2006-03-27 01:14:55 -0800214 unsigned int len = 0;
215 unsigned int hash = 0;
Ian Kenta5370552006-05-15 09:43:51 -0700216 int status, type;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217
218 /* In catatonic mode, we don't wait for nobody */
Ian Kente77fbdd2006-03-27 01:14:49 -0800219 if (sbi->catatonic)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 return -ENOENT;
221
222 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
223 if (!name)
224 return -ENOMEM;
225
Ian Kent5c0a32f2006-03-27 01:14:55 -0800226 /* If this is a direct mount request create a dummy name */
Ian Kent44d53eb2006-03-27 01:14:56 -0800227 if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))
Ian Kent5c0a32f2006-03-27 01:14:55 -0800228 len = sprintf(name, "%p", dentry);
229 else {
230 len = autofs4_getpath(sbi, dentry, &name);
231 if (!len) {
232 kfree(name);
233 return -ENOENT;
234 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 }
Ian Kent5c0a32f2006-03-27 01:14:55 -0800236 hash = full_name_hash(name, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237
Ingo Molnar1d5599e2006-03-23 03:00:41 -0800238 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 kfree(name);
240 return -EINTR;
241 }
242
Ian Kenta5370552006-05-15 09:43:51 -0700243 wq = autofs4_find_wait(sbi, name, hash, len);
244 ino = autofs4_dentry_ino(dentry);
245 if (!wq && ino && notify == NFY_NONE) {
246 /*
247 * Either we've betean the pending expire to post it's
248 * wait or it finished while we waited on the mutex.
249 * So we need to wait till either, the wait appears
250 * or the expire finishes.
251 */
252
253 while (ino->flags & AUTOFS_INF_EXPIRING) {
254 mutex_unlock(&sbi->wq_mutex);
255 schedule_timeout_interruptible(HZ/10);
256 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
257 kfree(name);
258 return -EINTR;
259 }
260 wq = autofs4_find_wait(sbi, name, hash, len);
261 if (wq)
262 break;
263 }
264
265 /*
266 * Not ideal but the status has already gone. Of the two
267 * cases where we wait on NFY_NONE neither depend on the
268 * return status of the wait.
269 */
270 if (!wq) {
271 kfree(name);
272 mutex_unlock(&sbi->wq_mutex);
273 return 0;
274 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 }
276
Ian Kente77fbdd2006-03-27 01:14:49 -0800277 if (!wq) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 /* Create a new wait queue */
279 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
Ian Kente77fbdd2006-03-27 01:14:49 -0800280 if (!wq) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 kfree(name);
Ingo Molnar1d5599e2006-03-23 03:00:41 -0800282 mutex_unlock(&sbi->wq_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 return -ENOMEM;
284 }
285
286 wq->wait_queue_token = autofs4_next_wait_queue;
287 if (++autofs4_next_wait_queue == 0)
288 autofs4_next_wait_queue = 1;
289 wq->next = sbi->queues;
290 sbi->queues = wq;
291 init_waitqueue_head(&wq->queue);
Ian Kent5c0a32f2006-03-27 01:14:55 -0800292 wq->hash = hash;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 wq->name = name;
294 wq->len = len;
Ian Kent5c0a32f2006-03-27 01:14:55 -0800295 wq->dev = autofs4_get_dev(sbi);
296 wq->ino = autofs4_get_ino(sbi);
297 wq->uid = current->uid;
298 wq->gid = current->gid;
299 wq->pid = current->pid;
300 wq->tgid = current->tgid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 wq->status = -EINTR; /* Status return if interrupted */
302 atomic_set(&wq->wait_ctr, 2);
Ingo Molnar1d5599e2006-03-23 03:00:41 -0800303 mutex_unlock(&sbi->wq_mutex);
Ian Kent3e7b1912006-03-27 01:14:59 -0800304
Ian Kent5c0a32f2006-03-27 01:14:55 -0800305 if (sbi->version < 5) {
306 if (notify == NFY_MOUNT)
307 type = autofs_ptype_missing;
308 else
309 type = autofs_ptype_expire_multi;
310 } else {
311 if (notify == NFY_MOUNT)
Ian Kent44d53eb2006-03-27 01:14:56 -0800312 type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
Ian Kent5c0a32f2006-03-27 01:14:55 -0800313 autofs_ptype_missing_direct :
314 autofs_ptype_missing_indirect;
315 else
Ian Kent44d53eb2006-03-27 01:14:56 -0800316 type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
Ian Kent5c0a32f2006-03-27 01:14:55 -0800317 autofs_ptype_expire_direct :
318 autofs_ptype_expire_indirect;
319 }
Ian Kent4dcd00b2005-05-01 08:59:16 -0700320
Ian Kent682d4fc2005-07-07 17:57:02 -0700321 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
322 (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
Ian Kent4dcd00b2005-05-01 08:59:16 -0700323
324 /* autofs4_notify_daemon() may block */
325 autofs4_notify_daemon(sbi, wq, type);
Ian Kenta5370552006-05-15 09:43:51 -0700326 } else {
327 atomic_inc(&wq->wait_ctr);
328 mutex_unlock(&sbi->wq_mutex);
329 kfree(name);
330 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
331 (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
Ian Kent4dcd00b2005-05-01 08:59:16 -0700332 }
333
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 /* wq->name is NULL if and only if the lock is already released */
335
Ian Kente77fbdd2006-03-27 01:14:49 -0800336 if (sbi->catatonic) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 /* We might have slept, so check again for catatonic mode */
338 wq->status = -ENOENT;
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800339 kfree(wq->name);
340 wq->name = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 }
342
Ian Kente77fbdd2006-03-27 01:14:49 -0800343 if (wq->name) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 /* Block all but "shutdown" signals while waiting */
345 sigset_t oldset;
346 unsigned long irqflags;
347
348 spin_lock_irqsave(&current->sighand->siglock, irqflags);
349 oldset = current->blocked;
350 siginitsetinv(&current->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
351 recalc_sigpending();
352 spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
353
354 wait_event_interruptible(wq->queue, wq->name == NULL);
355
356 spin_lock_irqsave(&current->sighand->siglock, irqflags);
357 current->blocked = oldset;
358 recalc_sigpending();
359 spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
360 } else {
361 DPRINTK("skipped sleeping");
362 }
363
364 status = wq->status;
365
366 /* Are we the last process to need status? */
367 if (atomic_dec_and_test(&wq->wait_ctr))
368 kfree(wq);
369
370 return status;
371}
372
373
374int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
375{
376 struct autofs_wait_queue *wq, **wql;
377
Ingo Molnar1d5599e2006-03-23 03:00:41 -0800378 mutex_lock(&sbi->wq_mutex);
Stephen Hemmingerc80544d2007-10-18 03:07:05 -0700379 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
Ian Kente77fbdd2006-03-27 01:14:49 -0800380 if (wq->wait_queue_token == wait_queue_token)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 break;
382 }
383
Ian Kente77fbdd2006-03-27 01:14:49 -0800384 if (!wq) {
Ingo Molnar1d5599e2006-03-23 03:00:41 -0800385 mutex_unlock(&sbi->wq_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 return -EINVAL;
387 }
388
389 *wql = wq->next; /* Unlink from chain */
Ingo Molnar1d5599e2006-03-23 03:00:41 -0800390 mutex_unlock(&sbi->wq_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 kfree(wq->name);
392 wq->name = NULL; /* Do not wait on this queue */
393
394 wq->status = status;
395
396 if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */
397 kfree(wq);
398 else
399 wake_up_interruptible(&wq->queue);
400
401 return 0;
402}
403