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1da177e4 LT |
1 | /* -*- c -*- --------------------------------------------------------------- * |
2 | * | |
3 | * linux/fs/autofs/waitq.c | |
4 | * | |
5 | * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved | |
5c0a32fc | 6 | * Copyright 2001-2006 Ian Kent <raven@themaw.net> |
1da177e4 LT |
7 | * |
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 */ | |
22 | static 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 | ||
27 | void 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 */ | |
e77fbddf | 36 | while (wq) { |
1da177e4 LT |
37 | 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 | } | |
44 | if (sbi->pipe) { | |
45 | fput(sbi->pipe); /* Close the pipe */ | |
46 | sbi->pipe = NULL; | |
47 | } | |
1da177e4 LT |
48 | shrink_dcache_sb(sbi->sb); |
49 | } | |
50 | ||
51 | static int autofs4_write(struct file *file, const void *addr, int bytes) | |
52 | { | |
53 | unsigned long sigpipe, flags; | |
54 | mm_segment_t fs; | |
55 | const char *data = (const char *)addr; | |
56 | ssize_t wr = 0; | |
57 | ||
58 | /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/ | |
59 | ||
60 | sigpipe = sigismember(¤t->pending.signal, SIGPIPE); | |
61 | ||
62 | /* Save pointer to user space and point back to kernel space */ | |
63 | fs = get_fs(); | |
64 | set_fs(KERNEL_DS); | |
65 | ||
66 | while (bytes && | |
67 | (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) { | |
68 | data += wr; | |
69 | bytes -= wr; | |
70 | } | |
71 | ||
72 | set_fs(fs); | |
73 | ||
74 | /* Keep the currently executing process from receiving a | |
75 | SIGPIPE unless it was already supposed to get one */ | |
76 | if (wr == -EPIPE && !sigpipe) { | |
77 | spin_lock_irqsave(¤t->sighand->siglock, flags); | |
78 | sigdelset(¤t->pending.signal, SIGPIPE); | |
79 | recalc_sigpending(); | |
80 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); | |
81 | } | |
82 | ||
83 | return (bytes > 0); | |
84 | } | |
85 | ||
86 | static void autofs4_notify_daemon(struct autofs_sb_info *sbi, | |
87 | struct autofs_wait_queue *wq, | |
88 | int type) | |
89 | { | |
90 | union autofs_packet_union pkt; | |
91 | size_t pktsz; | |
92 | ||
93 | DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d", | |
94 | wq->wait_queue_token, wq->len, wq->name, type); | |
95 | ||
96 | memset(&pkt,0,sizeof pkt); /* For security reasons */ | |
97 | ||
98 | pkt.hdr.proto_version = sbi->version; | |
99 | pkt.hdr.type = type; | |
5c0a32fc IK |
100 | switch (type) { |
101 | /* Kernel protocol v4 missing and expire packets */ | |
102 | case autofs_ptype_missing: | |
103 | { | |
1da177e4 LT |
104 | struct autofs_packet_missing *mp = &pkt.missing; |
105 | ||
106 | pktsz = sizeof(*mp); | |
107 | ||
108 | mp->wait_queue_token = wq->wait_queue_token; | |
109 | mp->len = wq->len; | |
110 | memcpy(mp->name, wq->name, wq->len); | |
111 | mp->name[wq->len] = '\0'; | |
5c0a32fc IK |
112 | break; |
113 | } | |
114 | case autofs_ptype_expire_multi: | |
115 | { | |
1da177e4 LT |
116 | struct autofs_packet_expire_multi *ep = &pkt.expire_multi; |
117 | ||
118 | pktsz = sizeof(*ep); | |
119 | ||
120 | ep->wait_queue_token = wq->wait_queue_token; | |
121 | ep->len = wq->len; | |
122 | memcpy(ep->name, wq->name, wq->len); | |
123 | ep->name[wq->len] = '\0'; | |
5c0a32fc IK |
124 | break; |
125 | } | |
126 | /* | |
127 | * Kernel protocol v5 packet for handling indirect and direct | |
128 | * mount missing and expire requests | |
129 | */ | |
130 | case autofs_ptype_missing_indirect: | |
131 | case autofs_ptype_expire_indirect: | |
132 | case autofs_ptype_missing_direct: | |
133 | case autofs_ptype_expire_direct: | |
134 | { | |
135 | struct autofs_v5_packet *packet = &pkt.v5_packet; | |
136 | ||
137 | pktsz = sizeof(*packet); | |
138 | ||
139 | packet->wait_queue_token = wq->wait_queue_token; | |
140 | packet->len = wq->len; | |
141 | memcpy(packet->name, wq->name, wq->len); | |
142 | packet->name[wq->len] = '\0'; | |
143 | packet->dev = wq->dev; | |
144 | packet->ino = wq->ino; | |
145 | packet->uid = wq->uid; | |
146 | packet->gid = wq->gid; | |
147 | packet->pid = wq->pid; | |
148 | packet->tgid = wq->tgid; | |
149 | break; | |
150 | } | |
151 | default: | |
1da177e4 LT |
152 | printk("autofs4_notify_daemon: bad type %d!\n", type); |
153 | return; | |
154 | } | |
155 | ||
156 | if (autofs4_write(sbi->pipe, &pkt, pktsz)) | |
157 | autofs4_catatonic_mode(sbi); | |
158 | } | |
159 | ||
160 | static int autofs4_getpath(struct autofs_sb_info *sbi, | |
161 | struct dentry *dentry, char **name) | |
162 | { | |
163 | struct dentry *root = sbi->sb->s_root; | |
164 | struct dentry *tmp; | |
165 | char *buf = *name; | |
166 | char *p; | |
167 | int len = 0; | |
168 | ||
169 | spin_lock(&dcache_lock); | |
170 | for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent) | |
171 | len += tmp->d_name.len + 1; | |
172 | ||
173 | if (--len > NAME_MAX) { | |
174 | spin_unlock(&dcache_lock); | |
175 | return 0; | |
176 | } | |
177 | ||
178 | *(buf + len) = '\0'; | |
179 | p = buf + len - dentry->d_name.len; | |
180 | strncpy(p, dentry->d_name.name, dentry->d_name.len); | |
181 | ||
182 | for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) { | |
183 | *(--p) = '/'; | |
184 | p -= tmp->d_name.len; | |
185 | strncpy(p, tmp->d_name.name, tmp->d_name.len); | |
186 | } | |
187 | spin_unlock(&dcache_lock); | |
188 | ||
189 | return len; | |
190 | } | |
191 | ||
192 | int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, | |
193 | enum autofs_notify notify) | |
194 | { | |
195 | struct autofs_wait_queue *wq; | |
196 | char *name; | |
5c0a32fc IK |
197 | unsigned int len = 0; |
198 | unsigned int hash = 0; | |
199 | int status; | |
1da177e4 LT |
200 | |
201 | /* In catatonic mode, we don't wait for nobody */ | |
e77fbddf | 202 | if (sbi->catatonic) |
1da177e4 LT |
203 | return -ENOENT; |
204 | ||
205 | name = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
206 | if (!name) | |
207 | return -ENOMEM; | |
208 | ||
5c0a32fc | 209 | /* If this is a direct mount request create a dummy name */ |
44d53eb0 | 210 | if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT)) |
5c0a32fc IK |
211 | len = sprintf(name, "%p", dentry); |
212 | else { | |
213 | len = autofs4_getpath(sbi, dentry, &name); | |
214 | if (!len) { | |
215 | kfree(name); | |
216 | return -ENOENT; | |
217 | } | |
1da177e4 | 218 | } |
5c0a32fc | 219 | hash = full_name_hash(name, len); |
1da177e4 | 220 | |
1d5599e3 | 221 | if (mutex_lock_interruptible(&sbi->wq_mutex)) { |
1da177e4 LT |
222 | kfree(name); |
223 | return -EINTR; | |
224 | } | |
225 | ||
226 | for (wq = sbi->queues ; wq ; wq = wq->next) { | |
227 | if (wq->hash == dentry->d_name.hash && | |
228 | wq->len == len && | |
229 | wq->name && !memcmp(wq->name, name, len)) | |
230 | break; | |
231 | } | |
232 | ||
e77fbddf | 233 | if (!wq) { |
cc9acc88 IK |
234 | /* Can't wait for an expire if there's no mount */ |
235 | if (notify == NFY_NONE && !d_mountpoint(dentry)) { | |
236 | kfree(name); | |
1d5599e3 | 237 | mutex_unlock(&sbi->wq_mutex); |
cc9acc88 IK |
238 | return -ENOENT; |
239 | } | |
240 | ||
1da177e4 LT |
241 | /* Create a new wait queue */ |
242 | wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL); | |
e77fbddf | 243 | if (!wq) { |
1da177e4 | 244 | kfree(name); |
1d5599e3 | 245 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
246 | return -ENOMEM; |
247 | } | |
248 | ||
249 | wq->wait_queue_token = autofs4_next_wait_queue; | |
250 | if (++autofs4_next_wait_queue == 0) | |
251 | autofs4_next_wait_queue = 1; | |
252 | wq->next = sbi->queues; | |
253 | sbi->queues = wq; | |
254 | init_waitqueue_head(&wq->queue); | |
5c0a32fc | 255 | wq->hash = hash; |
1da177e4 LT |
256 | wq->name = name; |
257 | wq->len = len; | |
5c0a32fc IK |
258 | wq->dev = autofs4_get_dev(sbi); |
259 | wq->ino = autofs4_get_ino(sbi); | |
260 | wq->uid = current->uid; | |
261 | wq->gid = current->gid; | |
262 | wq->pid = current->pid; | |
263 | wq->tgid = current->tgid; | |
1da177e4 LT |
264 | wq->status = -EINTR; /* Status return if interrupted */ |
265 | atomic_set(&wq->wait_ctr, 2); | |
3e7b1919 | 266 | atomic_set(&wq->notify, 1); |
1d5599e3 | 267 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
268 | } else { |
269 | atomic_inc(&wq->wait_ctr); | |
1d5599e3 | 270 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
271 | kfree(name); |
272 | DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d", | |
273 | (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify); | |
274 | } | |
275 | ||
3e7b1919 | 276 | if (notify != NFY_NONE && atomic_read(&wq->notify)) { |
5c0a32fc IK |
277 | int type; |
278 | ||
3e7b1919 IK |
279 | atomic_dec(&wq->notify); |
280 | ||
5c0a32fc IK |
281 | if (sbi->version < 5) { |
282 | if (notify == NFY_MOUNT) | |
283 | type = autofs_ptype_missing; | |
284 | else | |
285 | type = autofs_ptype_expire_multi; | |
286 | } else { | |
287 | if (notify == NFY_MOUNT) | |
44d53eb0 | 288 | type = (sbi->type & AUTOFS_TYPE_DIRECT) ? |
5c0a32fc IK |
289 | autofs_ptype_missing_direct : |
290 | autofs_ptype_missing_indirect; | |
291 | else | |
44d53eb0 | 292 | type = (sbi->type & AUTOFS_TYPE_DIRECT) ? |
5c0a32fc IK |
293 | autofs_ptype_expire_direct : |
294 | autofs_ptype_expire_indirect; | |
295 | } | |
4dcd00b1 | 296 | |
682d4fc9 IK |
297 | DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n", |
298 | (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify); | |
4dcd00b1 IK |
299 | |
300 | /* autofs4_notify_daemon() may block */ | |
301 | autofs4_notify_daemon(sbi, wq, type); | |
302 | } | |
303 | ||
1da177e4 LT |
304 | /* wq->name is NULL if and only if the lock is already released */ |
305 | ||
e77fbddf | 306 | if (sbi->catatonic) { |
1da177e4 LT |
307 | /* We might have slept, so check again for catatonic mode */ |
308 | wq->status = -ENOENT; | |
f99d49ad JJ |
309 | kfree(wq->name); |
310 | wq->name = NULL; | |
1da177e4 LT |
311 | } |
312 | ||
e77fbddf | 313 | if (wq->name) { |
1da177e4 LT |
314 | /* Block all but "shutdown" signals while waiting */ |
315 | sigset_t oldset; | |
316 | unsigned long irqflags; | |
317 | ||
318 | spin_lock_irqsave(¤t->sighand->siglock, irqflags); | |
319 | oldset = current->blocked; | |
320 | siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]); | |
321 | recalc_sigpending(); | |
322 | spin_unlock_irqrestore(¤t->sighand->siglock, irqflags); | |
323 | ||
324 | wait_event_interruptible(wq->queue, wq->name == NULL); | |
325 | ||
326 | spin_lock_irqsave(¤t->sighand->siglock, irqflags); | |
327 | current->blocked = oldset; | |
328 | recalc_sigpending(); | |
329 | spin_unlock_irqrestore(¤t->sighand->siglock, irqflags); | |
330 | } else { | |
331 | DPRINTK("skipped sleeping"); | |
332 | } | |
333 | ||
334 | status = wq->status; | |
335 | ||
336 | /* Are we the last process to need status? */ | |
337 | if (atomic_dec_and_test(&wq->wait_ctr)) | |
338 | kfree(wq); | |
339 | ||
340 | return status; | |
341 | } | |
342 | ||
343 | ||
344 | int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status) | |
345 | { | |
346 | struct autofs_wait_queue *wq, **wql; | |
347 | ||
1d5599e3 | 348 | mutex_lock(&sbi->wq_mutex); |
e77fbddf IK |
349 | for (wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next) { |
350 | if (wq->wait_queue_token == wait_queue_token) | |
1da177e4 LT |
351 | break; |
352 | } | |
353 | ||
e77fbddf | 354 | if (!wq) { |
1d5599e3 | 355 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
356 | return -EINVAL; |
357 | } | |
358 | ||
359 | *wql = wq->next; /* Unlink from chain */ | |
1d5599e3 | 360 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
361 | kfree(wq->name); |
362 | wq->name = NULL; /* Do not wait on this queue */ | |
363 | ||
364 | wq->status = status; | |
365 | ||
366 | if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */ | |
367 | kfree(wq); | |
368 | else | |
369 | wake_up_interruptible(&wq->queue); | |
370 | ||
371 | return 0; | |
372 | } | |
373 |