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

/* -*- c -*- --------------------------------------------------------------- *
 *
 * linux/fs/autofs/waitq.c
 *
 *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
 *  Copyright 2001-2006 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;

	mutex_lock(&sbi->wq_mutex);
	if (sbi->catatonic) {
		mutex_unlock(&sbi->wq_mutex);
		return;
	}

	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 */
		if (wq->name.name) {
			kfree(wq->name.name);
			wq->name.name = NULL;
		}
		wake_up_interruptible(&wq->queue);
		wq = nwq;
	}
	fput(sbi->pipe);	/* Close the pipe */
	sbi->pipe = NULL;
	sbi->pipefd = -1;
	mutex_unlock(&sbi->wq_mutex);
}

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 {
		struct autofs_packet_hdr hdr;
		union autofs_packet_union v4_pkt;
		union autofs_v5_packet_union v5_pkt;
	} pkt;
	size_t pktsz;

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

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

	pkt.hdr.proto_version = sbi->version;
	pkt.hdr.type = type;
	switch (type) {
	/* Kernel protocol v4 missing and expire packets */
	case autofs_ptype_missing:
	{
		struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;

		pktsz = sizeof(*mp);

		mp->wait_queue_token = wq->wait_queue_token;
		mp->len = wq->name.len;
		memcpy(mp->name, wq->name.name, wq->name.len);
		mp->name[wq->name.len] = '\0';
		break;
	}
	case autofs_ptype_expire_multi:
	{
		struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;

		pktsz = sizeof(*ep);

		ep->wait_queue_token = wq->wait_queue_token;
		ep->len = wq->name.len;
		memcpy(ep->name, wq->name.name, wq->name.len);
		ep->name[wq->name.len] = '\0';
		break;
	}
	/*
	 * Kernel protocol v5 packet for handling indirect and direct
	 * mount missing and expire requests
	 */
	case autofs_ptype_missing_indirect:
	case autofs_ptype_expire_indirect:
	case autofs_ptype_missing_direct:
	case autofs_ptype_expire_direct:
	{
		struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;

		pktsz = sizeof(*packet);

		packet->wait_queue_token = wq->wait_queue_token;
		packet->len = wq->name.len;
		memcpy(packet->name, wq->name.name, wq->name.len);
		packet->name[wq->name.len] = '\0';
		packet->dev = wq->dev;
		packet->ino = wq->ino;
		packet->uid = wq->uid;
		packet->gid = wq->gid;
		packet->pid = wq->pid;
		packet->tgid = wq->tgid;
		break;
	}
	default:
		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 || --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;
}

static struct autofs_wait_queue *
autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
{
	struct autofs_wait_queue *wq;

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

/*
 * Check if we have a valid request.
 * Returns
 * 1 if the request should continue.
 *   In this case we can return an autofs_wait_queue entry if one is
 *   found or NULL to idicate a new wait needs to be created.
 * 0 or a negative errno if the request shouldn't continue.
 */
static int validate_request(struct autofs_wait_queue **wait,
			    struct autofs_sb_info *sbi,
			    struct qstr *qstr,
			    struct dentry*dentry, enum autofs_notify notify)
{
	struct autofs_wait_queue *wq;
	struct autofs_info *ino;

	/* Wait in progress, continue; */
	wq = autofs4_find_wait(sbi, qstr);
	if (wq) {
		*wait = wq;
		return 1;
	}

	*wait = NULL;

	/* If we don't yet have any info this is a new request */
	ino = autofs4_dentry_ino(dentry);
	if (!ino)
		return 1;

	/*
	 * If we've been asked to wait on an existing expire (NFY_NONE)
	 * but there is no wait in the queue ...
	 */
	if (notify == NFY_NONE) {
		/*
		 * Either we've betean the pending expire to post it's
		 * wait or it finished while we waited on the mutex.
		 * So we need to wait till either, the wait appears
		 * or the expire finishes.
		 */

		while (ino->flags & AUTOFS_INF_EXPIRING) {
			mutex_unlock(&sbi->wq_mutex);
			schedule_timeout_interruptible(HZ/10);
			if (mutex_lock_interruptible(&sbi->wq_mutex))
				return -EINTR;

			wq = autofs4_find_wait(sbi, qstr);
			if (wq) {
				*wait = wq;
				return 1;
			}
		}

		/*
		 * Not ideal but the status has already gone. Of the two
		 * cases where we wait on NFY_NONE neither depend on the
		 * return status of the wait.
		 */
		return 0;
	}

	/*
	 * If we've been asked to trigger a mount and the request
	 * completed while we waited on the mutex ...
	 */
	if (notify == NFY_MOUNT) {
		/*
		 * If the dentry isn't hashed just go ahead and try the
		 * mount again with a new wait (not much else we can do).
		*/
		if (!d_unhashed(dentry)) {
			/*
			 * But if the dentry is hashed, that means that we
			 * got here through the revalidate path.  Thus, we
			 * need to check if the dentry has been mounted
			 * while we waited on the wq_mutex. If it has,
			 * simply return success.
			 */
			if (d_mountpoint(dentry))
				return 0;
		}
	}

	return 1;
}

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

	/* 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;

	/* If this is a direct mount request create a dummy name */
	if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))
		qstr.len = sprintf(name, "%p", dentry);
	else {
		qstr.len = autofs4_getpath(sbi, dentry, &name);
		if (!qstr.len) {
			kfree(name);
			return -ENOENT;
		}
	}
	qstr.name = name;
	qstr.hash = full_name_hash(name, qstr.len);

	if (mutex_lock_interruptible(&sbi->wq_mutex))
		return -EINTR;

	ret = validate_request(&wq, sbi, &qstr, dentry, notify);
	if (ret <= 0) {
		if (ret == 0)
			mutex_unlock(&sbi->wq_mutex);
		kfree(qstr.name);
		return ret;
	}

	if (!wq) {
		/* Create a new wait queue */
		wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
		if (!wq) {
			kfree(qstr.name);
			mutex_unlock(&sbi->wq_mutex);
			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);
		memcpy(&wq->name, &qstr, sizeof(struct qstr));
		wq->dev = autofs4_get_dev(sbi);
		wq->ino = autofs4_get_ino(sbi);
		wq->uid = current->uid;
		wq->gid = current->gid;
		wq->pid = current->pid;
		wq->tgid = current->tgid;
		wq->status = -EINTR; /* Status return if interrupted */
		atomic_set(&wq->wait_ctr, 2);
		mutex_unlock(&sbi->wq_mutex);

		if (sbi->version < 5) {
			if (notify == NFY_MOUNT)
				type = autofs_ptype_missing;
			else
				type = autofs_ptype_expire_multi;
		} else {
			if (notify == NFY_MOUNT)
				type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
					autofs_ptype_missing_direct :
					 autofs_ptype_missing_indirect;
			else
				type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
					autofs_ptype_expire_direct :
					autofs_ptype_expire_indirect;
		}

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

		/* autofs4_notify_daemon() may block */
		autofs4_notify_daemon(sbi, wq, type);
	} else {
		atomic_inc(&wq->wait_ctr);
		mutex_unlock(&sbi->wq_mutex);
		kfree(qstr.name);
		DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
			(unsigned long) wq->wait_queue_token, wq->name.len,
			wq->name.name, notify);
	}

	/*
	 * wq->name.name is NULL iff the lock is already released
	 * or the mount has been made catatonic.
	 */
	if (wq->name.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.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;

	mutex_lock(&sbi->wq_mutex);
	for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
		if (wq->wait_queue_token == wait_queue_token)
			break;
	}

	if (!wq) {
		mutex_unlock(&sbi->wq_mutex);
		return -EINVAL;
	}

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

	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
5c0a32fc	6	* Copyright 2001-2006 Ian Kent <raven@themaw.net>
1da177e4 LT	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
5a11d4d0 IK	31	mutex_lock(&sbi->wq_mutex);
	32	if (sbi->catatonic) {
	33	mutex_unlock(&sbi->wq_mutex);
	34	return;
	35	}
	36
1da177e4 LT	37	DPRINTK("entering catatonic mode");
	38
	39	sbi->catatonic = 1;
	40	wq = sbi->queues;
	41	sbi->queues = NULL; /* Erase all wait queues */
e77fbddf	42	while (wq) {
1da177e4 LT	43	nwq = wq->next;
1da177e4 LT	44	wq->status = -ENOENT; /* Magic is gone - report failure */
70b52a0a JM	45	if (wq->name.name) {
	46	kfree(wq->name.name);
	47	wq->name.name = NULL;
	48	}
1da177e4 LT	49	wake_up_interruptible(&wq->queue);
	50	wq = nwq;
	51	}
ba8df43c IK	52	fput(sbi->pipe); /* Close the pipe */
ba8df43c IK	53	sbi->pipe = NULL;
5a11d4d0 IK	54	sbi->pipefd = -1;
5a11d4d0 IK	55	mutex_unlock(&sbi->wq_mutex);
1da177e4 LT	56	}
	57
	58	static int autofs4_write(struct file file, const void addr, int bytes)
	59	{
	60	unsigned long sigpipe, flags;
	61	mm_segment_t fs;
	62	const char data = (const char )addr;
	63	ssize_t wr = 0;
	64
	65	/ WARNING: this is not safe for writing more than PIPE_BUF bytes! /
	66
	67	sigpipe = sigismember(&current->pending.signal, SIGPIPE);
	68
	69	/* Save pointer to user space and point back to kernel space */
	70	fs = get_fs();
	71	set_fs(KERNEL_DS);
	72
	73	while (bytes &&
	74	(wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
	75	data += wr;
	76	bytes -= wr;
	77	}
	78
	79	set_fs(fs);
	80
	81	/* Keep the currently executing process from receiving a
	82	SIGPIPE unless it was already supposed to get one */
	83	if (wr == -EPIPE && !sigpipe) {
	84	spin_lock_irqsave(&current->sighand->siglock, flags);
	85	sigdelset(&current->pending.signal, SIGPIPE);
	86	recalc_sigpending();
	87	spin_unlock_irqrestore(&current->sighand->siglock, flags);
	88	}
	89
	90	return (bytes > 0);
	91	}
	92
	93	static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
	94	struct autofs_wait_queue *wq,
	95	int type)
	96	{
e8514478 IK	97	union {
	98	struct autofs_packet_hdr hdr;
	99	union autofs_packet_union v4_pkt;
	100	union autofs_v5_packet_union v5_pkt;
	101	} pkt;
1da177e4 LT	102	size_t pktsz;
	103
	104	DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
70b52a0a	105	wq->wait_queue_token, wq->name.len, wq->name.name, type);
1da177e4 LT	106
	107	memset(&pkt,0,sizeof pkt); /* For security reasons */
	108
	109	pkt.hdr.proto_version = sbi->version;
	110	pkt.hdr.type = type;
5c0a32fc IK	111	switch (type) {
	112	/* Kernel protocol v4 missing and expire packets */
	113	case autofs_ptype_missing:
	114	{
e8514478	115	struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
1da177e4 LT	116
	117	pktsz = sizeof(*mp);
	118
	119	mp->wait_queue_token = wq->wait_queue_token;
70b52a0a JM	120	mp->len = wq->name.len;
	121	memcpy(mp->name, wq->name.name, wq->name.len);
	122	mp->name[wq->name.len] = '\0';
5c0a32fc IK	123	break;
	124	}
	125	case autofs_ptype_expire_multi:
	126	{
e8514478	127	struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
1da177e4 LT	128
	129	pktsz = sizeof(*ep);
	130
	131	ep->wait_queue_token = wq->wait_queue_token;
70b52a0a JM	132	ep->len = wq->name.len;
	133	memcpy(ep->name, wq->name.name, wq->name.len);
	134	ep->name[wq->name.len] = '\0';
5c0a32fc IK	135	break;
	136	}
	137	/*
	138	* Kernel protocol v5 packet for handling indirect and direct
	139	* mount missing and expire requests
	140	*/
	141	case autofs_ptype_missing_indirect:
	142	case autofs_ptype_expire_indirect:
	143	case autofs_ptype_missing_direct:
	144	case autofs_ptype_expire_direct:
	145	{
e8514478	146	struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
5c0a32fc IK	147
	148	pktsz = sizeof(*packet);
	149
	150	packet->wait_queue_token = wq->wait_queue_token;
70b52a0a JM	151	packet->len = wq->name.len;
	152	memcpy(packet->name, wq->name.name, wq->name.len);
	153	packet->name[wq->name.len] = '\0';
5c0a32fc IK	154	packet->dev = wq->dev;
	155	packet->ino = wq->ino;
	156	packet->uid = wq->uid;
	157	packet->gid = wq->gid;
	158	packet->pid = wq->pid;
	159	packet->tgid = wq->tgid;
	160	break;
	161	}
	162	default:
1da177e4 LT	163	printk("autofs4_notify_daemon: bad type %d!\n", type);
	164	return;
	165	}
	166
	167	if (autofs4_write(sbi->pipe, &pkt, pktsz))
	168	autofs4_catatonic_mode(sbi);
	169	}
	170
	171	static int autofs4_getpath(struct autofs_sb_info *sbi,
	172	struct dentry dentry, char *name)
	173	{
	174	struct dentry *root = sbi->sb->s_root;
	175	struct dentry *tmp;
	176	char buf = name;
	177	char *p;
	178	int len = 0;
	179
	180	spin_lock(&dcache_lock);
	181	for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
	182	len += tmp->d_name.len + 1;
	183
cab0936a	184	if (!len \|\| --len > NAME_MAX) {
1da177e4 LT	185	spin_unlock(&dcache_lock);
	186	return 0;
	187	}
	188
	189	*(buf + len) = '\0';
	190	p = buf + len - dentry->d_name.len;
	191	strncpy(p, dentry->d_name.name, dentry->d_name.len);
	192
	193	for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
	194	*(--p) = '/';
	195	p -= tmp->d_name.len;
	196	strncpy(p, tmp->d_name.name, tmp->d_name.len);
	197	}
	198	spin_unlock(&dcache_lock);
	199
	200	return len;
	201	}
	202
a5370553	203	static struct autofs_wait_queue *
70b52a0a	204	autofs4_find_wait(struct autofs_sb_info sbi, struct qstr qstr)
a5370553 IK	205	{
	206	struct autofs_wait_queue *wq;
	207
	208	for (wq = sbi->queues; wq; wq = wq->next) {
70b52a0a JM	209	if (wq->name.hash == qstr->hash &&
	210	wq->name.len == qstr->len &&
	211	wq->name.name &&
	212	!memcmp(wq->name.name, qstr->name, qstr->len))
a5370553 IK	213	break;
	214	}
	215	return wq;
	216	}
	217
a1362fe9 IK	218	/*
	219	* Check if we have a valid request.
	220	* Returns
	221	* 1 if the request should continue.
	222	* In this case we can return an autofs_wait_queue entry if one is
	223	* found or NULL to idicate a new wait needs to be created.
	224	* 0 or a negative errno if the request shouldn't continue.
	225	*/
	226	static int validate_request(struct autofs_wait_queue **wait,
	227	struct autofs_sb_info *sbi,
	228	struct qstr *qstr,
	229	struct dentry*dentry, enum autofs_notify notify)
	230	{
	231	struct autofs_wait_queue *wq;
	232	struct autofs_info *ino;
	233
	234	/* Wait in progress, continue; */
	235	wq = autofs4_find_wait(sbi, qstr);
	236	if (wq) {
	237	*wait = wq;
	238	return 1;
	239	}
	240
	241	*wait = NULL;
	242
	243	/* If we don't yet have any info this is a new request */
	244	ino = autofs4_dentry_ino(dentry);
	245	if (!ino)
	246	return 1;
	247
	248	/*
	249	* If we've been asked to wait on an existing expire (NFY_NONE)
	250	* but there is no wait in the queue ...
	251	*/
	252	if (notify == NFY_NONE) {
	253	/*
	254	* Either we've betean the pending expire to post it's
	255	* wait or it finished while we waited on the mutex.
	256	* So we need to wait till either, the wait appears
	257	* or the expire finishes.
	258	*/
	259
	260	while (ino->flags & AUTOFS_INF_EXPIRING) {
	261	mutex_unlock(&sbi->wq_mutex);
	262	schedule_timeout_interruptible(HZ/10);
	263	if (mutex_lock_interruptible(&sbi->wq_mutex))
	264	return -EINTR;
	265
	266	wq = autofs4_find_wait(sbi, qstr);
	267	if (wq) {
	268	*wait = wq;
	269	return 1;
	270	}
	271	}
	272
	273	/*
	274	* Not ideal but the status has already gone. Of the two
	275	* cases where we wait on NFY_NONE neither depend on the
	276	* return status of the wait.
	277	*/
	278	return 0;
	279	}
	280
	281	/*
282	* If we've been asked to trigger a mount and the request
283	* completed while we waited on the mutex ...
284	*/
285	if (notify == NFY_MOUNT) {
286	/*
287	* If the dentry isn't hashed just go ahead and try the
288	* mount again with a new wait (not much else we can do).
289	*/
290	if (!d_unhashed(dentry)) {
291	/*
292	* But if the dentry is hashed, that means that we
293	* got here through the revalidate path. Thus, we
294	* need to check if the dentry has been mounted
295	* while we waited on the wq_mutex. If it has,
296	* simply return success.
297	*/
298	if (d_mountpoint(dentry))
299	return 0;
300	}
301	}
302
303	return 1;
304	}
305
1da177e4 LT	306	int autofs4_wait(struct autofs_sb_info sbi, struct dentry dentry,
	307	enum autofs_notify notify)
	308	{
	309	struct autofs_wait_queue *wq;
70b52a0a	310	struct qstr qstr;
1da177e4	311	char *name;
a1362fe9	312	int status, ret, type;
1da177e4 LT	313
1da177e4 LT	314	/* In catatonic mode, we don't wait for nobody */
e77fbddf	315	if (sbi->catatonic)
1da177e4	316	return -ENOENT;
a1362fe9	317
1da177e4 LT	318	name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
	319	if (!name)
	320	return -ENOMEM;
	321
5c0a32fc	322	/* If this is a direct mount request create a dummy name */
44d53eb0	323	if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))
70b52a0a	324	qstr.len = sprintf(name, "%p", dentry);
5c0a32fc	325	else {
70b52a0a JM	326	qstr.len = autofs4_getpath(sbi, dentry, &name);
70b52a0a JM	327	if (!qstr.len) {
5c0a32fc IK	328	kfree(name);
	329	return -ENOENT;
	330	}
1da177e4	331	}
70b52a0a JM	332	qstr.name = name;
70b52a0a JM	333	qstr.hash = full_name_hash(name, qstr.len);
1da177e4	334
a1362fe9	335	if (mutex_lock_interruptible(&sbi->wq_mutex))
1da177e4	336	return -EINTR;
a5370553	337
a1362fe9 IK	338	ret = validate_request(&wq, sbi, &qstr, dentry, notify);
	339	if (ret <= 0) {
	340	if (ret == 0)
1d5599e3	341	mutex_unlock(&sbi->wq_mutex);
a1362fe9 IK	342	kfree(qstr.name);
a1362fe9 IK	343	return ret;
a5370553	344	}
cc9acc88	345
a5370553	346	if (!wq) {
1da177e4 LT	347	/* Create a new wait queue */
1da177e4 LT	348	wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
e77fbddf	349	if (!wq) {
70b52a0a	350	kfree(qstr.name);
1d5599e3	351	mutex_unlock(&sbi->wq_mutex);
1da177e4 LT	352	return -ENOMEM;
	353	}
	354
	355	wq->wait_queue_token = autofs4_next_wait_queue;
	356	if (++autofs4_next_wait_queue == 0)
	357	autofs4_next_wait_queue = 1;
	358	wq->next = sbi->queues;
	359	sbi->queues = wq;
	360	init_waitqueue_head(&wq->queue);
70b52a0a	361	memcpy(&wq->name, &qstr, sizeof(struct qstr));
5c0a32fc IK	362	wq->dev = autofs4_get_dev(sbi);
	363	wq->ino = autofs4_get_ino(sbi);
	364	wq->uid = current->uid;
	365	wq->gid = current->gid;
	366	wq->pid = current->pid;
	367	wq->tgid = current->tgid;
1da177e4 LT	368	wq->status = -EINTR; /* Status return if interrupted */
1da177e4 LT	369	atomic_set(&wq->wait_ctr, 2);
1d5599e3	370	mutex_unlock(&sbi->wq_mutex);
3e7b1919	371
5c0a32fc IK	372	if (sbi->version < 5) {
	373	if (notify == NFY_MOUNT)
	374	type = autofs_ptype_missing;
	375	else
	376	type = autofs_ptype_expire_multi;
	377	} else {
	378	if (notify == NFY_MOUNT)
44d53eb0	379	type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
5c0a32fc IK	380	autofs_ptype_missing_direct :
	381	autofs_ptype_missing_indirect;
	382	else
44d53eb0	383	type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
5c0a32fc IK	384	autofs_ptype_expire_direct :
	385	autofs_ptype_expire_indirect;
	386	}
4dcd00b1	387
682d4fc9	388	DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
70b52a0a JM	389	(unsigned long) wq->wait_queue_token, wq->name.len,
70b52a0a JM	390	wq->name.name, notify);
4dcd00b1 IK	391
	392	/* autofs4_notify_daemon() may block */
	393	autofs4_notify_daemon(sbi, wq, type);
a5370553 IK	394	} else {
	395	atomic_inc(&wq->wait_ctr);
	396	mutex_unlock(&sbi->wq_mutex);
70b52a0a	397	kfree(qstr.name);
a5370553	398	DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
70b52a0a JM	399	(unsigned long) wq->wait_queue_token, wq->name.len,
70b52a0a JM	400	wq->name.name, notify);
4dcd00b1 IK	401	}
4dcd00b1 IK	402
5a11d4d0 IK	403	/*
	404	* wq->name.name is NULL iff the lock is already released
	405	* or the mount has been made catatonic.
	406	*/
70b52a0a	407	if (wq->name.name) {
1da177e4 LT	408	/* Block all but "shutdown" signals while waiting */
	409	sigset_t oldset;
	410	unsigned long irqflags;
	411
	412	spin_lock_irqsave(&current->sighand->siglock, irqflags);
	413	oldset = current->blocked;
	414	siginitsetinv(&current->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
	415	recalc_sigpending();
	416	spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
	417
70b52a0a	418	wait_event_interruptible(wq->queue, wq->name.name == NULL);
1da177e4 LT	419
	420	spin_lock_irqsave(&current->sighand->siglock, irqflags);
	421	current->blocked = oldset;
	422	recalc_sigpending();
	423	spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
	424	} else {
	425	DPRINTK("skipped sleeping");
	426	}
	427
	428	status = wq->status;
	429
	430	/* Are we the last process to need status? */
	431	if (atomic_dec_and_test(&wq->wait_ctr))
	432	kfree(wq);
	433
	434	return status;
	435	}
	436
	437
	438	int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
	439	{
	440	struct autofs_wait_queue wq, *wql;
	441
1d5599e3	442	mutex_lock(&sbi->wq_mutex);
c80544dc	443	for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
e77fbddf	444	if (wq->wait_queue_token == wait_queue_token)
1da177e4 LT	445	break;
	446	}
	447
e77fbddf	448	if (!wq) {
1d5599e3	449	mutex_unlock(&sbi->wq_mutex);
1da177e4 LT	450	return -EINVAL;
	451	}
	452
	453	wql = wq->next; / Unlink from chain */
70b52a0a JM	454	kfree(wq->name.name);
70b52a0a JM	455	wq->name.name = NULL; /* Do not wait on this queue */
a1362fe9	456	mutex_unlock(&sbi->wq_mutex);
1da177e4 LT	457
	458	wq->status = status;
	459
	460	if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */
	461	kfree(wq);
	462	else
	463	wake_up_interruptible(&wq->queue);
	464
	465	return 0;
	466	}
	467