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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 | |
6 | * Copyright 2001-2003 Ian Kent <raven@themaw.net> | |
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; | |
100 | if (type == autofs_ptype_missing) { | |
101 | struct autofs_packet_missing *mp = &pkt.missing; | |
102 | ||
103 | pktsz = sizeof(*mp); | |
104 | ||
105 | mp->wait_queue_token = wq->wait_queue_token; | |
106 | mp->len = wq->len; | |
107 | memcpy(mp->name, wq->name, wq->len); | |
108 | mp->name[wq->len] = '\0'; | |
109 | } else if (type == autofs_ptype_expire_multi) { | |
110 | struct autofs_packet_expire_multi *ep = &pkt.expire_multi; | |
111 | ||
112 | pktsz = sizeof(*ep); | |
113 | ||
114 | ep->wait_queue_token = wq->wait_queue_token; | |
115 | ep->len = wq->len; | |
116 | memcpy(ep->name, wq->name, wq->len); | |
117 | ep->name[wq->len] = '\0'; | |
118 | } else { | |
119 | printk("autofs4_notify_daemon: bad type %d!\n", type); | |
120 | return; | |
121 | } | |
122 | ||
123 | if (autofs4_write(sbi->pipe, &pkt, pktsz)) | |
124 | autofs4_catatonic_mode(sbi); | |
125 | } | |
126 | ||
127 | static int autofs4_getpath(struct autofs_sb_info *sbi, | |
128 | struct dentry *dentry, char **name) | |
129 | { | |
130 | struct dentry *root = sbi->sb->s_root; | |
131 | struct dentry *tmp; | |
132 | char *buf = *name; | |
133 | char *p; | |
134 | int len = 0; | |
135 | ||
136 | spin_lock(&dcache_lock); | |
137 | for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent) | |
138 | len += tmp->d_name.len + 1; | |
139 | ||
140 | if (--len > NAME_MAX) { | |
141 | spin_unlock(&dcache_lock); | |
142 | return 0; | |
143 | } | |
144 | ||
145 | *(buf + len) = '\0'; | |
146 | p = buf + len - dentry->d_name.len; | |
147 | strncpy(p, dentry->d_name.name, dentry->d_name.len); | |
148 | ||
149 | for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) { | |
150 | *(--p) = '/'; | |
151 | p -= tmp->d_name.len; | |
152 | strncpy(p, tmp->d_name.name, tmp->d_name.len); | |
153 | } | |
154 | spin_unlock(&dcache_lock); | |
155 | ||
156 | return len; | |
157 | } | |
158 | ||
159 | int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, | |
160 | enum autofs_notify notify) | |
161 | { | |
162 | struct autofs_wait_queue *wq; | |
163 | char *name; | |
164 | int len, status; | |
165 | ||
166 | /* In catatonic mode, we don't wait for nobody */ | |
e77fbddf | 167 | if (sbi->catatonic) |
1da177e4 LT |
168 | return -ENOENT; |
169 | ||
170 | name = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
171 | if (!name) | |
172 | return -ENOMEM; | |
173 | ||
174 | len = autofs4_getpath(sbi, dentry, &name); | |
175 | if (!len) { | |
176 | kfree(name); | |
177 | return -ENOENT; | |
178 | } | |
179 | ||
1d5599e3 | 180 | if (mutex_lock_interruptible(&sbi->wq_mutex)) { |
1da177e4 LT |
181 | kfree(name); |
182 | return -EINTR; | |
183 | } | |
184 | ||
185 | for (wq = sbi->queues ; wq ; wq = wq->next) { | |
186 | if (wq->hash == dentry->d_name.hash && | |
187 | wq->len == len && | |
188 | wq->name && !memcmp(wq->name, name, len)) | |
189 | break; | |
190 | } | |
191 | ||
e77fbddf | 192 | if (!wq) { |
cc9acc88 IK |
193 | /* Can't wait for an expire if there's no mount */ |
194 | if (notify == NFY_NONE && !d_mountpoint(dentry)) { | |
195 | kfree(name); | |
1d5599e3 | 196 | mutex_unlock(&sbi->wq_mutex); |
cc9acc88 IK |
197 | return -ENOENT; |
198 | } | |
199 | ||
1da177e4 LT |
200 | /* Create a new wait queue */ |
201 | wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL); | |
e77fbddf | 202 | if (!wq) { |
1da177e4 | 203 | kfree(name); |
1d5599e3 | 204 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
205 | return -ENOMEM; |
206 | } | |
207 | ||
208 | wq->wait_queue_token = autofs4_next_wait_queue; | |
209 | if (++autofs4_next_wait_queue == 0) | |
210 | autofs4_next_wait_queue = 1; | |
211 | wq->next = sbi->queues; | |
212 | sbi->queues = wq; | |
213 | init_waitqueue_head(&wq->queue); | |
214 | wq->hash = dentry->d_name.hash; | |
215 | wq->name = name; | |
216 | wq->len = len; | |
217 | wq->status = -EINTR; /* Status return if interrupted */ | |
218 | atomic_set(&wq->wait_ctr, 2); | |
4dcd00b1 | 219 | atomic_set(&wq->notified, 1); |
1d5599e3 | 220 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
221 | } else { |
222 | atomic_inc(&wq->wait_ctr); | |
1d5599e3 | 223 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
224 | kfree(name); |
225 | DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d", | |
226 | (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify); | |
227 | } | |
228 | ||
4dcd00b1 IK |
229 | if (notify != NFY_NONE && atomic_dec_and_test(&wq->notified)) { |
230 | int type = (notify == NFY_MOUNT ? | |
231 | autofs_ptype_missing : autofs_ptype_expire_multi); | |
232 | ||
682d4fc9 IK |
233 | DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n", |
234 | (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify); | |
4dcd00b1 IK |
235 | |
236 | /* autofs4_notify_daemon() may block */ | |
237 | autofs4_notify_daemon(sbi, wq, type); | |
238 | } | |
239 | ||
1da177e4 LT |
240 | /* wq->name is NULL if and only if the lock is already released */ |
241 | ||
e77fbddf | 242 | if (sbi->catatonic) { |
1da177e4 LT |
243 | /* We might have slept, so check again for catatonic mode */ |
244 | wq->status = -ENOENT; | |
f99d49ad JJ |
245 | kfree(wq->name); |
246 | wq->name = NULL; | |
1da177e4 LT |
247 | } |
248 | ||
e77fbddf | 249 | if (wq->name) { |
1da177e4 LT |
250 | /* Block all but "shutdown" signals while waiting */ |
251 | sigset_t oldset; | |
252 | unsigned long irqflags; | |
253 | ||
254 | spin_lock_irqsave(¤t->sighand->siglock, irqflags); | |
255 | oldset = current->blocked; | |
256 | siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]); | |
257 | recalc_sigpending(); | |
258 | spin_unlock_irqrestore(¤t->sighand->siglock, irqflags); | |
259 | ||
260 | wait_event_interruptible(wq->queue, wq->name == NULL); | |
261 | ||
262 | spin_lock_irqsave(¤t->sighand->siglock, irqflags); | |
263 | current->blocked = oldset; | |
264 | recalc_sigpending(); | |
265 | spin_unlock_irqrestore(¤t->sighand->siglock, irqflags); | |
266 | } else { | |
267 | DPRINTK("skipped sleeping"); | |
268 | } | |
269 | ||
270 | status = wq->status; | |
271 | ||
272 | /* Are we the last process to need status? */ | |
273 | if (atomic_dec_and_test(&wq->wait_ctr)) | |
274 | kfree(wq); | |
275 | ||
276 | return status; | |
277 | } | |
278 | ||
279 | ||
280 | int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status) | |
281 | { | |
282 | struct autofs_wait_queue *wq, **wql; | |
283 | ||
1d5599e3 | 284 | mutex_lock(&sbi->wq_mutex); |
e77fbddf IK |
285 | for (wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next) { |
286 | if (wq->wait_queue_token == wait_queue_token) | |
1da177e4 LT |
287 | break; |
288 | } | |
289 | ||
e77fbddf | 290 | if (!wq) { |
1d5599e3 | 291 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
292 | return -EINVAL; |
293 | } | |
294 | ||
295 | *wql = wq->next; /* Unlink from chain */ | |
1d5599e3 | 296 | mutex_unlock(&sbi->wq_mutex); |
1da177e4 LT |
297 | kfree(wq->name); |
298 | wq->name = NULL; /* Do not wait on this queue */ | |
299 | ||
300 | wq->status = status; | |
301 | ||
302 | if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */ | |
303 | kfree(wq); | |
304 | else | |
305 | wake_up_interruptible(&wq->queue); | |
306 | ||
307 | return 0; | |
308 | } | |
309 |