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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 */ | |
36 | while ( wq ) { | |
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 | } | |
48 | ||
49 | shrink_dcache_sb(sbi->sb); | |
50 | } | |
51 | ||
52 | static int autofs4_write(struct file *file, const void *addr, int bytes) | |
53 | { | |
54 | unsigned long sigpipe, flags; | |
55 | mm_segment_t fs; | |
56 | const char *data = (const char *)addr; | |
57 | ssize_t wr = 0; | |
58 | ||
59 | /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/ | |
60 | ||
61 | sigpipe = sigismember(¤t->pending.signal, SIGPIPE); | |
62 | ||
63 | /* Save pointer to user space and point back to kernel space */ | |
64 | fs = get_fs(); | |
65 | set_fs(KERNEL_DS); | |
66 | ||
67 | while (bytes && | |
68 | (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) { | |
69 | data += wr; | |
70 | bytes -= wr; | |
71 | } | |
72 | ||
73 | set_fs(fs); | |
74 | ||
75 | /* Keep the currently executing process from receiving a | |
76 | SIGPIPE unless it was already supposed to get one */ | |
77 | if (wr == -EPIPE && !sigpipe) { | |
78 | spin_lock_irqsave(¤t->sighand->siglock, flags); | |
79 | sigdelset(¤t->pending.signal, SIGPIPE); | |
80 | recalc_sigpending(); | |
81 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); | |
82 | } | |
83 | ||
84 | return (bytes > 0); | |
85 | } | |
86 | ||
87 | static void autofs4_notify_daemon(struct autofs_sb_info *sbi, | |
88 | struct autofs_wait_queue *wq, | |
89 | int type) | |
90 | { | |
91 | union autofs_packet_union pkt; | |
92 | 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; | |
101 | if (type == autofs_ptype_missing) { | |
102 | struct autofs_packet_missing *mp = &pkt.missing; | |
103 | ||
104 | pktsz = sizeof(*mp); | |
105 | ||
106 | mp->wait_queue_token = wq->wait_queue_token; | |
107 | mp->len = wq->len; | |
108 | memcpy(mp->name, wq->name, wq->len); | |
109 | mp->name[wq->len] = '\0'; | |
110 | } else if (type == autofs_ptype_expire_multi) { | |
111 | struct autofs_packet_expire_multi *ep = &pkt.expire_multi; | |
112 | ||
113 | pktsz = sizeof(*ep); | |
114 | ||
115 | ep->wait_queue_token = wq->wait_queue_token; | |
116 | ep->len = wq->len; | |
117 | memcpy(ep->name, wq->name, wq->len); | |
118 | ep->name[wq->len] = '\0'; | |
119 | } else { | |
120 | printk("autofs4_notify_daemon: bad type %d!\n", type); | |
121 | return; | |
122 | } | |
123 | ||
124 | if (autofs4_write(sbi->pipe, &pkt, pktsz)) | |
125 | autofs4_catatonic_mode(sbi); | |
126 | } | |
127 | ||
128 | static int autofs4_getpath(struct autofs_sb_info *sbi, | |
129 | struct dentry *dentry, char **name) | |
130 | { | |
131 | struct dentry *root = sbi->sb->s_root; | |
132 | struct dentry *tmp; | |
133 | char *buf = *name; | |
134 | char *p; | |
135 | int len = 0; | |
136 | ||
137 | spin_lock(&dcache_lock); | |
138 | for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent) | |
139 | len += tmp->d_name.len + 1; | |
140 | ||
141 | if (--len > NAME_MAX) { | |
142 | spin_unlock(&dcache_lock); | |
143 | return 0; | |
144 | } | |
145 | ||
146 | *(buf + len) = '\0'; | |
147 | p = buf + len - dentry->d_name.len; | |
148 | strncpy(p, dentry->d_name.name, dentry->d_name.len); | |
149 | ||
150 | for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) { | |
151 | *(--p) = '/'; | |
152 | p -= tmp->d_name.len; | |
153 | strncpy(p, tmp->d_name.name, tmp->d_name.len); | |
154 | } | |
155 | spin_unlock(&dcache_lock); | |
156 | ||
157 | return len; | |
158 | } | |
159 | ||
160 | int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, | |
161 | enum autofs_notify notify) | |
162 | { | |
163 | struct autofs_wait_queue *wq; | |
164 | char *name; | |
165 | int len, status; | |
166 | ||
167 | /* In catatonic mode, we don't wait for nobody */ | |
168 | if ( sbi->catatonic ) | |
169 | return -ENOENT; | |
170 | ||
171 | name = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
172 | if (!name) | |
173 | return -ENOMEM; | |
174 | ||
175 | len = autofs4_getpath(sbi, dentry, &name); | |
176 | if (!len) { | |
177 | kfree(name); | |
178 | return -ENOENT; | |
179 | } | |
180 | ||
181 | if (down_interruptible(&sbi->wq_sem)) { | |
182 | kfree(name); | |
183 | return -EINTR; | |
184 | } | |
185 | ||
186 | for (wq = sbi->queues ; wq ; wq = wq->next) { | |
187 | if (wq->hash == dentry->d_name.hash && | |
188 | wq->len == len && | |
189 | wq->name && !memcmp(wq->name, name, len)) | |
190 | break; | |
191 | } | |
192 | ||
193 | if ( !wq ) { | |
194 | /* Create a new wait queue */ | |
195 | wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL); | |
196 | if ( !wq ) { | |
197 | kfree(name); | |
198 | up(&sbi->wq_sem); | |
199 | return -ENOMEM; | |
200 | } | |
201 | ||
202 | wq->wait_queue_token = autofs4_next_wait_queue; | |
203 | if (++autofs4_next_wait_queue == 0) | |
204 | autofs4_next_wait_queue = 1; | |
205 | wq->next = sbi->queues; | |
206 | sbi->queues = wq; | |
207 | init_waitqueue_head(&wq->queue); | |
208 | wq->hash = dentry->d_name.hash; | |
209 | wq->name = name; | |
210 | wq->len = len; | |
211 | wq->status = -EINTR; /* Status return if interrupted */ | |
212 | atomic_set(&wq->wait_ctr, 2); | |
213 | up(&sbi->wq_sem); | |
214 | ||
215 | DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d", | |
216 | (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify); | |
217 | /* autofs4_notify_daemon() may block */ | |
218 | if (notify != NFY_NONE) { | |
219 | autofs4_notify_daemon(sbi,wq, | |
220 | notify == NFY_MOUNT ? | |
221 | autofs_ptype_missing : | |
222 | autofs_ptype_expire_multi); | |
223 | } | |
224 | } else { | |
225 | atomic_inc(&wq->wait_ctr); | |
226 | up(&sbi->wq_sem); | |
227 | kfree(name); | |
228 | DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d", | |
229 | (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify); | |
230 | } | |
231 | ||
232 | /* wq->name is NULL if and only if the lock is already released */ | |
233 | ||
234 | if ( sbi->catatonic ) { | |
235 | /* We might have slept, so check again for catatonic mode */ | |
236 | wq->status = -ENOENT; | |
237 | if ( wq->name ) { | |
238 | kfree(wq->name); | |
239 | wq->name = NULL; | |
240 | } | |
241 | } | |
242 | ||
243 | if ( wq->name ) { | |
244 | /* Block all but "shutdown" signals while waiting */ | |
245 | sigset_t oldset; | |
246 | unsigned long irqflags; | |
247 | ||
248 | spin_lock_irqsave(¤t->sighand->siglock, irqflags); | |
249 | oldset = current->blocked; | |
250 | siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]); | |
251 | recalc_sigpending(); | |
252 | spin_unlock_irqrestore(¤t->sighand->siglock, irqflags); | |
253 | ||
254 | wait_event_interruptible(wq->queue, wq->name == NULL); | |
255 | ||
256 | spin_lock_irqsave(¤t->sighand->siglock, irqflags); | |
257 | current->blocked = oldset; | |
258 | recalc_sigpending(); | |
259 | spin_unlock_irqrestore(¤t->sighand->siglock, irqflags); | |
260 | } else { | |
261 | DPRINTK("skipped sleeping"); | |
262 | } | |
263 | ||
264 | status = wq->status; | |
265 | ||
266 | /* Are we the last process to need status? */ | |
267 | if (atomic_dec_and_test(&wq->wait_ctr)) | |
268 | kfree(wq); | |
269 | ||
270 | return status; | |
271 | } | |
272 | ||
273 | ||
274 | int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status) | |
275 | { | |
276 | struct autofs_wait_queue *wq, **wql; | |
277 | ||
278 | down(&sbi->wq_sem); | |
279 | for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) { | |
280 | if ( wq->wait_queue_token == wait_queue_token ) | |
281 | break; | |
282 | } | |
283 | ||
284 | if ( !wq ) { | |
285 | up(&sbi->wq_sem); | |
286 | return -EINVAL; | |
287 | } | |
288 | ||
289 | *wql = wq->next; /* Unlink from chain */ | |
290 | up(&sbi->wq_sem); | |
291 | kfree(wq->name); | |
292 | wq->name = NULL; /* Do not wait on this queue */ | |
293 | ||
294 | wq->status = status; | |
295 | ||
296 | if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */ | |
297 | kfree(wq); | |
298 | else | |
299 | wake_up_interruptible(&wq->queue); | |
300 | ||
301 | return 0; | |
302 | } | |
303 |