Merge 'acpi-2.6.12' branch into to-akpm
[linux-2.6] / fs / autofs4 / waitq.c
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(&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         
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                 /* 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
201                 /* 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);
220                 atomic_set(&wq->notified, 1);
221                 up(&sbi->wq_sem);
222         } 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
230         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
234                 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
235                         (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
236
237                 /* autofs4_notify_daemon() may block */
238                 autofs4_notify_daemon(sbi, wq, type);
239         }
240
241         /* 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
283 int 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