1/* -*- c -*- --------------------------------------------------------------- *
2 *
3 * linux/fs/autofs/waitq.c
4 *
5 *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 *
7 * This file is part of the Linux kernel and is made available under
8 * the terms of the GNU General Public License, version 2, or at your
9 * option, any later version, incorporated herein by reference.
10 *
11 * ------------------------------------------------------------------------- */
12
13#include <linux/slab.h>
14#include <linux/sched.h>
15#include <linux/signal.h>
16#include <linux/file.h>
17#include "autofs_i.h"
18
19/* We make this a static variable rather than a part of the superblock; it
20   is better if we don't reassign numbers easily even across filesystems */
21static autofs_wqt_t autofs4_next_wait_queue = 1;
22
23/* These are the signals we allow interrupting a pending mount */
24#define SHUTDOWN_SIGS	(sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
25
26void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
27{
28	struct autofs_wait_queue *wq, *nwq;
29
30	DPRINTK(("autofs: entering catatonic mode\n"));
31
32	sbi->catatonic = 1;
33	wq = sbi->queues;
34	sbi->queues = NULL;	/* Erase all wait queues */
35	while ( wq ) {
36		nwq = wq->next;
37		wq->status = -ENOENT; /* Magic is gone - report failure */
38		kfree(wq->name);
39		wq->name = NULL;
40		wake_up(&wq->queue);
41		wq = nwq;
42	}
43	if (sbi->pipe) {
44		fput(sbi->pipe);	/* Close the pipe */
45		sbi->pipe = NULL;
46	}
47
48	shrink_dcache_sb(sbi->sb);
49}
50
51static 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(&current->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(&current->sigmask_lock, flags);
78		sigdelset(&current->pending.signal, SIGPIPE);
79		recalc_sigpending(current);
80		spin_unlock_irqrestore(&current->sigmask_lock, flags);
81	}
82
83	return (bytes > 0);
84}
85
86static 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(("autofs_notify: wait id = 0x%08lx, name = %.*s, type=%d\n",
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("autofs_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
127int autofs4_wait(struct autofs_sb_info *sbi, struct qstr *name,
128		enum autofs_notify notify)
129{
130	struct autofs_wait_queue *wq;
131	int status;
132
133	/* In catatonic mode, we don't wait for nobody */
134	if ( sbi->catatonic )
135		return -ENOENT;
136
137	/* We shouldn't be able to get here, but just in case */
138	if ( name->len > NAME_MAX )
139		return -ENOENT;
140
141	for ( wq = sbi->queues ; wq ; wq = wq->next ) {
142		if ( wq->hash == name->hash &&
143		     wq->len == name->len &&
144		     wq->name && !memcmp(wq->name,name->name,name->len) )
145			break;
146	}
147
148	if ( !wq ) {
149		/* Create a new wait queue */
150		wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
151		if ( !wq )
152			return -ENOMEM;
153
154		wq->name = kmalloc(name->len,GFP_KERNEL);
155		if ( !wq->name ) {
156			kfree(wq);
157			return -ENOMEM;
158		}
159		wq->wait_queue_token = autofs4_next_wait_queue;
160		if (++autofs4_next_wait_queue == 0)
161			autofs4_next_wait_queue = 1;
162		init_waitqueue_head(&wq->queue);
163		wq->hash = name->hash;
164		wq->len = name->len;
165		wq->status = -EINTR; /* Status return if interrupted */
166		memcpy(wq->name, name->name, name->len);
167		wq->next = sbi->queues;
168		sbi->queues = wq;
169
170		DPRINTK(("autofs_wait: new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
171			 wq->wait_queue_token, wq->len, wq->name, notify));
172		/* autofs4_notify_daemon() may block */
173		wq->wait_ctr = 2;
174		if (notify != NFY_NONE) {
175			autofs4_notify_daemon(sbi,wq,
176					      notify == NFY_MOUNT ? autofs_ptype_missing :
177								    autofs_ptype_expire_multi);
178		}
179	} else {
180		wq->wait_ctr++;
181		DPRINTK(("autofs_wait: existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
182			 wq->wait_queue_token, wq->len, wq->name, notify));
183	}
184
185	/* wq->name is NULL if and only if the lock is already released */
186
187	if ( sbi->catatonic ) {
188		/* We might have slept, so check again for catatonic mode */
189		wq->status = -ENOENT;
190		if ( wq->name ) {
191			kfree(wq->name);
192			wq->name = NULL;
193		}
194	}
195
196	if ( wq->name ) {
197		/* Block all but "shutdown" signals while waiting */
198		sigset_t oldset;
199		unsigned long irqflags;
200
201		spin_lock_irqsave(&current->sigmask_lock, irqflags);
202		oldset = current->blocked;
203		siginitsetinv(&current->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
204		recalc_sigpending(current);
205		spin_unlock_irqrestore(&current->sigmask_lock, irqflags);
206
207		interruptible_sleep_on(&wq->queue);
208
209		spin_lock_irqsave(&current->sigmask_lock, irqflags);
210		current->blocked = oldset;
211		recalc_sigpending(current);
212		spin_unlock_irqrestore(&current->sigmask_lock, irqflags);
213	} else {
214		DPRINTK(("autofs_wait: skipped sleeping\n"));
215	}
216
217	status = wq->status;
218
219	if (--wq->wait_ctr == 0)	/* Are we the last process to need status? */
220		kfree(wq);
221
222	return status;
223}
224
225
226int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
227{
228	struct autofs_wait_queue *wq, **wql;
229
230	for ( wql = &sbi->queues ; (wq = *wql) ; wql = &wq->next ) {
231		if ( wq->wait_queue_token == wait_queue_token )
232			break;
233	}
234	if ( !wq )
235		return -EINVAL;
236
237	*wql = wq->next;	/* Unlink from chain */
238	kfree(wq->name);
239	wq->name = NULL;	/* Do not wait on this queue */
240
241	wq->status = status;
242
243	if (--wq->wait_ctr == 0)	/* Is anyone still waiting for this guy? */
244		kfree(wq);
245	else
246		wake_up(&wq->queue);
247
248	return 0;
249}
250
251