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 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
228 (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
229 }
230
231 /* wq->name is NULL if and only if the lock is already released */
232
233 if ( sbi->catatonic ) {
234 /* We might have slept, so check again for catatonic mode */
235 wq->status = -ENOENT;
236 if ( wq->name ) {
237 kfree(wq->name);
238 wq->name = NULL;
239 }
240 }
241
242 if ( wq->name ) {
243 /* Block all but "shutdown" signals while waiting */
244 sigset_t oldset;
245 unsigned long irqflags;
246
247 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
248 oldset = current->blocked;
249 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
250 recalc_sigpending();
251 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
252
253 wait_event_interruptible(wq->queue, wq->name == NULL);
254
255 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
256 current->blocked = oldset;
257 recalc_sigpending();
258 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
259 } else {
260 DPRINTK("skipped sleeping");
261 }
262
263 status = wq->status;
264
265 /* Are we the last process to need status? */
266 if (atomic_dec_and_test(&wq->wait_ctr))
267 kfree(wq);
268
269 return status;
270 }
271
272
273 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
274 {
275 struct autofs_wait_queue *wq, **wql;
276
277 down(&sbi->wq_sem);
278 for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) {
279 if ( wq->wait_queue_token == wait_queue_token )
280 break;
281 }
282
283 if ( !wq ) {
284 up(&sbi->wq_sem);
285 return -EINVAL;
286 }
287
288 *wql = wq->next; /* Unlink from chain */
289 up(&sbi->wq_sem);
290 kfree(wq->name);
291 wq->name = NULL; /* Do not wait on this queue */
292
293 wq->status = status;
294
295 if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */
296 kfree(wq);
297 else
298 wake_up_interruptible(&wq->queue);
299
300 return 0;
301 }
302
303
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