[linux-2.6-block.git] / fs / autofs4 / waitq.c

/* -*- c -*- --------------------------------------------------------------- *
 *
 * linux/fs/autofs/waitq.c
 *
 *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
 *  Copyright 2001-2003 Ian Kent <raven@themaw.net>
 *
 * This file is part of the Linux kernel and is made available under
 * the terms of the GNU General Public License, version 2, or at your
 * option, any later version, incorporated herein by reference.
 *
 * ------------------------------------------------------------------------- */

#include <linux/slab.h>
#include <linux/time.h>
#include <linux/signal.h>
#include <linux/file.h>
#include "autofs_i.h"

/* We make this a static variable rather than a part of the superblock; it
   is better if we don't reassign numbers easily even across filesystems */
static autofs_wqt_t autofs4_next_wait_queue = 1;

/* These are the signals we allow interrupting a pending mount */
#define SHUTDOWN_SIGS	(sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))

void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
{
	struct autofs_wait_queue *wq, *nwq;

	DPRINTK("entering catatonic mode");

	sbi->catatonic = 1;
	wq = sbi->queues;
	sbi->queues = NULL;	/* Erase all wait queues */
	while ( wq ) {
		nwq = wq->next;
		wq->status = -ENOENT; /* Magic is gone - report failure */
		kfree(wq->name);
		wq->name = NULL;
		wake_up_interruptible(&wq->queue);
		wq = nwq;
	}
	if (sbi->pipe) {
		fput(sbi->pipe);	/* Close the pipe */
		sbi->pipe = NULL;
	}

	shrink_dcache_sb(sbi->sb);
}

static int autofs4_write(struct file *file, const void *addr, int bytes)
{
	unsigned long sigpipe, flags;
	mm_segment_t fs;
	const char *data = (const char *)addr;
	ssize_t wr = 0;

	/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/

	sigpipe = sigismember(&current->pending.signal, SIGPIPE);

	/* Save pointer to user space and point back to kernel space */
	fs = get_fs();
	set_fs(KERNEL_DS);

	while (bytes &&
	       (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
		data += wr;
		bytes -= wr;
	}

	set_fs(fs);

	/* Keep the currently executing process from receiving a
	   SIGPIPE unless it was already supposed to get one */
	if (wr == -EPIPE && !sigpipe) {
		spin_lock_irqsave(&current->sighand->siglock, flags);
		sigdelset(&current->pending.signal, SIGPIPE);
		recalc_sigpending();
		spin_unlock_irqrestore(&current->sighand->siglock, flags);
	}

	return (bytes > 0);
}
	
static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
				 struct autofs_wait_queue *wq,
				 int type)
{
	union autofs_packet_union pkt;
	size_t pktsz;

	DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
		wq->wait_queue_token, wq->len, wq->name, type);

	memset(&pkt,0,sizeof pkt); /* For security reasons */

	pkt.hdr.proto_version = sbi->version;
	pkt.hdr.type = type;
	if (type == autofs_ptype_missing) {
		struct autofs_packet_missing *mp = &pkt.missing;

		pktsz = sizeof(*mp);

		mp->wait_queue_token = wq->wait_queue_token;
		mp->len = wq->len;
		memcpy(mp->name, wq->name, wq->len);
		mp->name[wq->len] = '\0';
	} else if (type == autofs_ptype_expire_multi) {
		struct autofs_packet_expire_multi *ep = &pkt.expire_multi;

		pktsz = sizeof(*ep);

		ep->wait_queue_token = wq->wait_queue_token;
		ep->len = wq->len;
		memcpy(ep->name, wq->name, wq->len);
		ep->name[wq->len] = '\0';
	} else {
		printk("autofs4_notify_daemon: bad type %d!\n", type);
		return;
	}

	if (autofs4_write(sbi->pipe, &pkt, pktsz))
		autofs4_catatonic_mode(sbi);
}

static int autofs4_getpath(struct autofs_sb_info *sbi,
			   struct dentry *dentry, char **name)
{
	struct dentry *root = sbi->sb->s_root;
	struct dentry *tmp;
	char *buf = *name;
	char *p;
	int len = 0;

	spin_lock(&dcache_lock);
	for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
		len += tmp->d_name.len + 1;

	if (--len > NAME_MAX) {
		spin_unlock(&dcache_lock);
		return 0;
	}

	*(buf + len) = '\0';
	p = buf + len - dentry->d_name.len;
	strncpy(p, dentry->d_name.name, dentry->d_name.len);

	for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
		*(--p) = '/';
		p -= tmp->d_name.len;
		strncpy(p, tmp->d_name.name, tmp->d_name.len);
	}
	spin_unlock(&dcache_lock);

	return len;
}

int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
		enum autofs_notify notify)
{
	struct autofs_wait_queue *wq;
	char *name;
	int len, status;

	/* In catatonic mode, we don't wait for nobody */
	if ( sbi->catatonic )
		return -ENOENT;
	
	name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
	if (!name)
		return -ENOMEM;

	len = autofs4_getpath(sbi, dentry, &name);
	if (!len) {
		kfree(name);
		return -ENOENT;
	}

	if (down_interruptible(&sbi->wq_sem)) {
		kfree(name);
		return -EINTR;
	}

	for (wq = sbi->queues ; wq ; wq = wq->next) {
		if (wq->hash == dentry->d_name.hash &&
		    wq->len == len &&
		    wq->name && !memcmp(wq->name, name, len))
			break;
	}

	if ( !wq ) {
		/* Can't wait for an expire if there's no mount */
		if (notify == NFY_NONE && !d_mountpoint(dentry)) {
			kfree(name);
			up(&sbi->wq_sem);
			return -ENOENT;
		}

		/* Create a new wait queue */
		wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
		if ( !wq ) {
			kfree(name);
			up(&sbi->wq_sem);
			return -ENOMEM;
		}

		wq->wait_queue_token = autofs4_next_wait_queue;
		if (++autofs4_next_wait_queue == 0)
			autofs4_next_wait_queue = 1;
		wq->next = sbi->queues;
		sbi->queues = wq;
		init_waitqueue_head(&wq->queue);
		wq->hash = dentry->d_name.hash;
		wq->name = name;
		wq->len = len;
		wq->status = -EINTR; /* Status return if interrupted */
		atomic_set(&wq->wait_ctr, 2);
		atomic_set(&wq->notified, 1);
		up(&sbi->wq_sem);
	} else {
		atomic_inc(&wq->wait_ctr);
		up(&sbi->wq_sem);
		kfree(name);
		DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
	}

	if (notify != NFY_NONE && atomic_dec_and_test(&wq->notified)) {
		int type = (notify == NFY_MOUNT ?
			autofs_ptype_missing : autofs_ptype_expire_multi);

		DPRINTK(("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify));

		/* autofs4_notify_daemon() may block */
		autofs4_notify_daemon(sbi, wq, type);
	}

	/* wq->name is NULL if and only if the lock is already released */

	if ( sbi->catatonic ) {
		/* We might have slept, so check again for catatonic mode */
		wq->status = -ENOENT;
		if ( wq->name ) {
			kfree(wq->name);
			wq->name = NULL;
		}
	}

	if ( wq->name ) {
		/* Block all but "shutdown" signals while waiting */
		sigset_t oldset;
		unsigned long irqflags;

		spin_lock_irqsave(&current->sighand->siglock, irqflags);
		oldset = current->blocked;
		siginitsetinv(&current->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
		recalc_sigpending();
		spin_unlock_irqrestore(&current->sighand->siglock, irqflags);

		wait_event_interruptible(wq->queue, wq->name == NULL);

		spin_lock_irqsave(&current->sighand->siglock, irqflags);
		current->blocked = oldset;
		recalc_sigpending();
		spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
	} else {
		DPRINTK("skipped sleeping");
	}

	status = wq->status;

	/* Are we the last process to need status? */
	if (atomic_dec_and_test(&wq->wait_ctr))
		kfree(wq);

	return status;
}


int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
{
	struct autofs_wait_queue *wq, **wql;

	down(&sbi->wq_sem);
	for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) {
		if ( wq->wait_queue_token == wait_queue_token )
			break;
	}

	if ( !wq ) {
		up(&sbi->wq_sem);
		return -EINVAL;
	}

	*wql = wq->next;	/* Unlink from chain */
	up(&sbi->wq_sem);
	kfree(wq->name);
	wq->name = NULL;	/* Do not wait on this queue */

	wq->status = status;

	if (atomic_dec_and_test(&wq->wait_ctr))	/* Is anyone still waiting for this guy? */
		kfree(wq);
	else
		wake_up_interruptible(&wq->queue);

	return 0;
}
Commit	Line	Data
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(&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 ) {
cc9acc88 IK	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
1da177e4 LT	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);
4dcd00b1	220	atomic_set(&wq->notified, 1);
1da177e4	221	up(&sbi->wq_sem);
1da177e4 LT	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
4dcd00b1 IK	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
1da177e4 LT	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