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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
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 */
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 */
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
52static 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(&current->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(&current->sighand->siglock, flags);
79 sigdelset(&current->pending.signal, SIGPIPE);
80 recalc_sigpending();
81 spin_unlock_irqrestore(&current->sighand->siglock, flags);
82 }
83
84 return (bytes > 0);
85}
86
87static 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
128static 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
160int 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 ) {
Ian Kentcc9acc82005-06-21 17:16:39 -0700194 /* Can't wait for an expire if there's no mount */
195 if (notify == NFY_NONE && !d_mountpoint(dentry)) {
196 kfree(name);
197 up(&sbi->wq_sem);
198 return -ENOENT;
199 }
200
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 /* Create a new wait queue */
202 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
203 if ( !wq ) {
204 kfree(name);
205 up(&sbi->wq_sem);
206 return -ENOMEM;
207 }
208
209 wq->wait_queue_token = autofs4_next_wait_queue;
210 if (++autofs4_next_wait_queue == 0)
211 autofs4_next_wait_queue = 1;
212 wq->next = sbi->queues;
213 sbi->queues = wq;
214 init_waitqueue_head(&wq->queue);
215 wq->hash = dentry->d_name.hash;
216 wq->name = name;
217 wq->len = len;
218 wq->status = -EINTR; /* Status return if interrupted */
219 atomic_set(&wq->wait_ctr, 2);
Ian Kent4dcd00b2005-05-01 08:59:16 -0700220 atomic_set(&wq->notified, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 up(&sbi->wq_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 } else {
223 atomic_inc(&wq->wait_ctr);
224 up(&sbi->wq_sem);
225 kfree(name);
226 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
227 (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
228 }
229
Ian Kent4dcd00b2005-05-01 08:59:16 -0700230 if (notify != NFY_NONE && atomic_dec_and_test(&wq->notified)) {
231 int type = (notify == NFY_MOUNT ?
232 autofs_ptype_missing : autofs_ptype_expire_multi);
233
Ian Kent682d4fc2005-07-07 17:57:02 -0700234 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
235 (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
Ian Kent4dcd00b2005-05-01 08:59:16 -0700236
237 /* autofs4_notify_daemon() may block */
238 autofs4_notify_daemon(sbi, wq, type);
239 }
240
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 /* wq->name is NULL if and only if the lock is already released */
242
243 if ( sbi->catatonic ) {
244 /* We might have slept, so check again for catatonic mode */
245 wq->status = -ENOENT;
246 if ( wq->name ) {
247 kfree(wq->name);
248 wq->name = NULL;
249 }
250 }
251
252 if ( wq->name ) {
253 /* Block all but "shutdown" signals while waiting */
254 sigset_t oldset;
255 unsigned long irqflags;
256
257 spin_lock_irqsave(&current->sighand->siglock, irqflags);
258 oldset = current->blocked;
259 siginitsetinv(&current->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
260 recalc_sigpending();
261 spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
262
263 wait_event_interruptible(wq->queue, wq->name == NULL);
264
265 spin_lock_irqsave(&current->sighand->siglock, irqflags);
266 current->blocked = oldset;
267 recalc_sigpending();
268 spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
269 } else {
270 DPRINTK("skipped sleeping");
271 }
272
273 status = wq->status;
274
275 /* Are we the last process to need status? */
276 if (atomic_dec_and_test(&wq->wait_ctr))
277 kfree(wq);
278
279 return status;
280}
281
282
283int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
284{
285 struct autofs_wait_queue *wq, **wql;
286
287 down(&sbi->wq_sem);
288 for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) {
289 if ( wq->wait_queue_token == wait_queue_token )
290 break;
291 }
292
293 if ( !wq ) {
294 up(&sbi->wq_sem);
295 return -EINVAL;
296 }
297
298 *wql = wq->next; /* Unlink from chain */
299 up(&sbi->wq_sem);
300 kfree(wq->name);
301 wq->name = NULL; /* Do not wait on this queue */
302
303 wq->status = status;
304
305 if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */
306 kfree(wq);
307 else
308 wake_up_interruptible(&wq->queue);
309
310 return 0;
311}
312