[linux-2.6-block.git] / 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/sched/signal.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 autofs_next_wait_queue = 1;

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

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

	pr_debug("entering catatonic mode\n");

	sbi->flags |= AUTOFS_SBI_CATATONIC;
	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.name);
		wq->name.name = NULL;
		wq->wait_ctr--;
		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 autofs_write(struct autofs_sb_info *sbi,
			struct file *file, const void *addr, int bytes)
{
	unsigned long sigpipe, flags;
	const char *data = (const char *)addr;
	ssize_t wr = 0;

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

	mutex_lock(&sbi->pipe_mutex);
	while (bytes) {
		wr = __kernel_write(file, data, bytes, &file->f_pos);
		if (wr <= 0)
			break;
		data += wr;
		bytes -= wr;
	}
	mutex_unlock(&sbi->pipe_mutex);

	/* 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);
	}

	/* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
	return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
}

static void autofs_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;
	struct file *pipe = NULL;
	size_t pktsz;
	int ret;

	pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n",
		 (unsigned long) 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;
		struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;

		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 = from_kuid_munged(user_ns, wq->uid);
		packet->gid = from_kgid_munged(user_ns, wq->gid);
		packet->pid = wq->pid;
		packet->tgid = wq->tgid;
		break;
	}
	default:
		pr_warn("bad type %d!\n", type);
		mutex_unlock(&sbi->wq_mutex);
		return;
	}

	pipe = get_file(sbi->pipe);

	mutex_unlock(&sbi->wq_mutex);

	switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) {
	case 0:
		break;
	case -ENOMEM:
	case -ERESTARTSYS:
		/* Just fail this one */
		autofs_wait_release(sbi, wq->wait_queue_token, ret);
		break;
	default:
		autofs_catatonic_mode(sbi);
		break;
	}
	fput(pipe);
}

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

rename_retry:
	buf = name;
	len = 0;

	seq = read_seqbegin(&rename_lock);
	rcu_read_lock();
	spin_lock(&sbi->fs_lock);
	for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
		len += tmp->d_name.len + 1;

	if (!len || --len > NAME_MAX) {
		spin_unlock(&sbi->fs_lock);
		rcu_read_unlock();
		if (read_seqretry(&rename_lock, seq))
			goto rename_retry;
		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(&sbi->fs_lock);
	rcu_read_unlock();
	if (read_seqretry(&rename_lock, seq))
		goto rename_retry;

	return len;
}

static struct autofs_wait_queue *
autofs_find_wait(struct autofs_sb_info *sbi, const 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,
			    const struct qstr *qstr,
			    const struct path *path, enum autofs_notify notify)
{
	struct dentry *dentry = path->dentry;
	struct autofs_wait_queue *wq;
	struct autofs_info *ino;

	if (sbi->flags & AUTOFS_SBI_CATATONIC)
		return -ENOENT;

	/* Wait in progress, continue; */
	wq = autofs_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 = autofs_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;

			if (sbi->flags & AUTOFS_SBI_CATATONIC)
				return -ENOENT;

			wq = autofs_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) {
		struct dentry *new = NULL;
		struct path this;
		int valid = 1;

		/*
		 * If the dentry was successfully mounted while we slept
		 * on the wait queue mutex we can return success. If it
		 * isn't mounted (doesn't have submounts for the case of
		 * a multi-mount with no mount at it's base) we can
		 * continue on and create a new request.
		 */
		if (!IS_ROOT(dentry)) {
			if (d_unhashed(dentry) &&
			    d_really_is_positive(dentry)) {
				struct dentry *parent = dentry->d_parent;

				new = d_lookup(parent, &dentry->d_name);
				if (new)
					dentry = new;
			}
		}
		this.mnt = path->mnt;
		this.dentry = dentry;
		if (path_has_submounts(&this))
			valid = 0;

		if (new)
			dput(new);
		return valid;
	}

	return 1;
}

int autofs_wait(struct autofs_sb_info *sbi,
		 const struct path *path, enum autofs_notify notify)
{
	struct dentry *dentry = path->dentry;
	struct autofs_wait_queue *wq;
	struct qstr qstr;
	char *name;
	int status, ret, type;
	pid_t pid;
	pid_t tgid;

	/* In catatonic mode, we don't wait for nobody */
	if (sbi->flags & AUTOFS_SBI_CATATONIC)
		return -ENOENT;

	/*
	 * Try translating pids to the namespace of the daemon.
	 *
	 * Zero means failure: we are in an unrelated pid namespace.
	 */
	pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
	tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
	if (pid == 0 || tgid == 0)
		return -ENOENT;

	if (d_really_is_negative(dentry)) {
		/*
		 * A wait for a negative dentry is invalid for certain
		 * cases. A direct or offset mount "always" has its mount
		 * point directory created and so the request dentry must
		 * be positive or the map key doesn't exist. The situation
		 * is very similar for indirect mounts except only dentrys
		 * in the root of the autofs file system may be negative.
		 */
		if (autofs_type_trigger(sbi->type))
			return -ENOENT;
		else if (!IS_ROOT(dentry->d_parent))
			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) && autofs_type_trigger(sbi->type))
		qstr.len = sprintf(name, "%p", dentry);
	else {
		qstr.len = autofs_getpath(sbi, dentry, name);
		if (!qstr.len) {
			kfree(name);
			return -ENOENT;
		}
	}
	qstr.name = name;
	qstr.hash = full_name_hash(dentry, name, qstr.len);

	if (mutex_lock_interruptible(&sbi->wq_mutex)) {
		kfree(qstr.name);
		return -EINTR;
	}

	ret = validate_request(&wq, sbi, &qstr, path, notify);
	if (ret <= 0) {
		if (ret != -EINTR)
			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 = autofs_next_wait_queue;
		if (++autofs_next_wait_queue == 0)
			autofs_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 = autofs_get_dev(sbi);
		wq->ino = autofs_get_ino(sbi);
		wq->uid = current_uid();
		wq->gid = current_gid();
		wq->pid = pid;
		wq->tgid = tgid;
		wq->status = -EINTR; /* Status return if interrupted */
		wq->wait_ctr = 2;

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

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

		/*
		 * autofs_notify_daemon() may block; it will unlock ->wq_mutex
		 */
		autofs_notify_daemon(sbi, wq, type);
	} else {
		wq->wait_ctr++;
		pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
			 (unsigned long) wq->wait_queue_token, wq->name.len,
			 wq->name.name, notify);
		mutex_unlock(&sbi->wq_mutex);
		kfree(qstr.name);
	}

	/*
	 * wq->name.name is NULL iff the lock is already released
	 * or the mount has been made catatonic.
	 */
	wait_event_killable(wq->queue, wq->name.name == NULL);
	status = wq->status;

	/*
	 * For direct and offset mounts we need to track the requester's
	 * uid and gid in the dentry info struct. This is so it can be
	 * supplied, on request, by the misc device ioctl interface.
	 * This is needed during daemon resatart when reconnecting
	 * to existing, active, autofs mounts. The uid and gid (and
	 * related string values) may be used for macro substitution
	 * in autofs mount maps.
	 */
	if (!status) {
		struct autofs_info *ino;
		struct dentry *de = NULL;

		/* direct mount or browsable map */
		ino = autofs_dentry_ino(dentry);
		if (!ino) {
			/* If not lookup actual dentry used */
			de = d_lookup(dentry->d_parent, &dentry->d_name);
			if (de)
				ino = autofs_dentry_ino(de);
		}

		/* Set mount requester */
		if (ino) {
			spin_lock(&sbi->fs_lock);
			ino->uid = wq->uid;
			ino->gid = wq->gid;
			spin_unlock(&sbi->fs_lock);
		}

		if (de)
			dput(de);
	}

	/* Are we the last process to need status? */
	mutex_lock(&sbi->wq_mutex);
	if (!--wq->wait_ctr)
		kfree(wq);
	mutex_unlock(&sbi->wq_mutex);

	return status;
}


int autofs_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 */
	wq->status = status;
	wake_up(&wq->queue);
	if (!--wq->wait_ctr)
		kfree(wq);
	mutex_unlock(&sbi->wq_mutex);

	return 0;
}
Commit	Line	Data
ebc921ca IK	1	/*
	2	* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
	3	* Copyright 2001-2006 Ian Kent <raven@themaw.net>
	4	*
	5	* This file is part of the Linux kernel and is made available under
	6	* the terms of the GNU General Public License, version 2, or at your
	7	* option, any later version, incorporated herein by reference.
	8	*/
	9
ebc921ca	10	#include <linux/sched/signal.h>
ebc921ca IK	11	#include "autofs_i.h"
	12
	13	/* We make this a static variable rather than a part of the superblock; it
	14	* is better if we don't reassign numbers easily even across filesystems
	15	*/
	16	static autofs_wqt_t autofs_next_wait_queue = 1;
	17
	18	void autofs_catatonic_mode(struct autofs_sb_info *sbi)
	19	{
	20	struct autofs_wait_queue wq, nwq;
	21
	22	mutex_lock(&sbi->wq_mutex);
9d8719a4	23	if (sbi->flags & AUTOFS_SBI_CATATONIC) {
ebc921ca IK	24	mutex_unlock(&sbi->wq_mutex);
	25	return;
	26	}
	27
	28	pr_debug("entering catatonic mode\n");
	29
9d8719a4	30	sbi->flags \|= AUTOFS_SBI_CATATONIC;
ebc921ca IK	31	wq = sbi->queues;
	32	sbi->queues = NULL; /* Erase all wait queues */
	33	while (wq) {
	34	nwq = wq->next;
	35	wq->status = -ENOENT; /* Magic is gone - report failure */
	36	kfree(wq->name.name);
	37	wq->name.name = NULL;
	38	wq->wait_ctr--;
	39	wake_up_interruptible(&wq->queue);
	40	wq = nwq;
	41	}
	42	fput(sbi->pipe); /* Close the pipe */
	43	sbi->pipe = NULL;
	44	sbi->pipefd = -1;
	45	mutex_unlock(&sbi->wq_mutex);
	46	}
	47
	48	static int autofs_write(struct autofs_sb_info *sbi,
	49	struct file file, const void addr, int bytes)
	50	{
	51	unsigned long sigpipe, flags;
	52	const char data = (const char )addr;
	53	ssize_t wr = 0;
	54
	55	sigpipe = sigismember(&current->pending.signal, SIGPIPE);
	56
	57	mutex_lock(&sbi->pipe_mutex);
	58	while (bytes) {
	59	wr = __kernel_write(file, data, bytes, &file->f_pos);
	60	if (wr <= 0)
	61	break;
	62	data += wr;
	63	bytes -= wr;
	64	}
	65	mutex_unlock(&sbi->pipe_mutex);
	66
	67	/* Keep the currently executing process from receiving a
	68	* SIGPIPE unless it was already supposed to get one
	69	*/
	70	if (wr == -EPIPE && !sigpipe) {
	71	spin_lock_irqsave(&current->sighand->siglock, flags);
	72	sigdelset(&current->pending.signal, SIGPIPE);
	73	recalc_sigpending();
	74	spin_unlock_irqrestore(&current->sighand->siglock, flags);
	75	}
	76
	77	/* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
	78	return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
	79	}
	80
	81	static void autofs_notify_daemon(struct autofs_sb_info *sbi,
	82	struct autofs_wait_queue *wq,
	83	int type)
	84	{
	85	union {
	86	struct autofs_packet_hdr hdr;
	87	union autofs_packet_union v4_pkt;
	88	union autofs_v5_packet_union v5_pkt;
	89	} pkt;
	90	struct file *pipe = NULL;
	91	size_t pktsz;
	92	int ret;
	93
	94	pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n",
95	(unsigned long) wq->wait_queue_token,
96	wq->name.len, wq->name.name, type);
97
98	memset(&pkt, 0, sizeof(pkt)); /* For security reasons */
99
100	pkt.hdr.proto_version = sbi->version;
101	pkt.hdr.type = type;
102
103	switch (type) {
104	/* Kernel protocol v4 missing and expire packets */
105	case autofs_ptype_missing:
106	{
107	struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
108
109	pktsz = sizeof(*mp);
110
111	mp->wait_queue_token = wq->wait_queue_token;
112	mp->len = wq->name.len;
113	memcpy(mp->name, wq->name.name, wq->name.len);
114	mp->name[wq->name.len] = '\0';
115	break;
116	}
117	case autofs_ptype_expire_multi:
118	{
119	struct autofs_packet_expire_multi *ep =
120	&pkt.v4_pkt.expire_multi;
121
122	pktsz = sizeof(*ep);
123
124	ep->wait_queue_token = wq->wait_queue_token;
125	ep->len = wq->name.len;
126	memcpy(ep->name, wq->name.name, wq->name.len);
127	ep->name[wq->name.len] = '\0';
128	break;
129	}
130	/*
131	* Kernel protocol v5 packet for handling indirect and direct
132	* mount missing and expire requests
133	*/
134	case autofs_ptype_missing_indirect:
135	case autofs_ptype_expire_indirect:
136	case autofs_ptype_missing_direct:
137	case autofs_ptype_expire_direct:
138	{
139	struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
140	struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
141
142	pktsz = sizeof(*packet);
143
144	packet->wait_queue_token = wq->wait_queue_token;
145	packet->len = wq->name.len;
146	memcpy(packet->name, wq->name.name, wq->name.len);
147	packet->name[wq->name.len] = '\0';
148	packet->dev = wq->dev;
149	packet->ino = wq->ino;
150	packet->uid = from_kuid_munged(user_ns, wq->uid);
151	packet->gid = from_kgid_munged(user_ns, wq->gid);
152	packet->pid = wq->pid;
153	packet->tgid = wq->tgid;
154	break;
155	}
156	default:
157	pr_warn("bad type %d!\n", type);
158	mutex_unlock(&sbi->wq_mutex);
159	return;
160	}
161
162	pipe = get_file(sbi->pipe);
163
164	mutex_unlock(&sbi->wq_mutex);
165
166	switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) {
167	case 0:
168	break;
169	case -ENOMEM:
170	case -ERESTARTSYS:
171	/* Just fail this one */
172	autofs_wait_release(sbi, wq->wait_queue_token, ret);
173	break;
174	default:
175	autofs_catatonic_mode(sbi);
176	break;
177	}
178	fput(pipe);
179	}
180
181	static int autofs_getpath(struct autofs_sb_info *sbi,
016e92da	182	struct dentry dentry, char name)
ebc921ca IK	183	{
	184	struct dentry *root = sbi->sb->s_root;
	185	struct dentry *tmp;
	186	char *buf;
	187	char *p;
	188	int len;
	189	unsigned seq;
	190
	191	rename_retry:
016e92da	192	buf = name;
ebc921ca IK	193	len = 0;
	194
	195	seq = read_seqbegin(&rename_lock);
	196	rcu_read_lock();
	197	spin_lock(&sbi->fs_lock);
	198	for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
	199	len += tmp->d_name.len + 1;
	200
	201	if (!len \|\| --len > NAME_MAX) {
	202	spin_unlock(&sbi->fs_lock);
	203	rcu_read_unlock();
	204	if (read_seqretry(&rename_lock, seq))
	205	goto rename_retry;
	206	return 0;
	207	}
	208
	209	*(buf + len) = '\0';
	210	p = buf + len - dentry->d_name.len;
	211	strncpy(p, dentry->d_name.name, dentry->d_name.len);
	212
	213	for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
	214	*(--p) = '/';
	215	p -= tmp->d_name.len;
	216	strncpy(p, tmp->d_name.name, tmp->d_name.len);
	217	}
	218	spin_unlock(&sbi->fs_lock);
	219	rcu_read_unlock();
	220	if (read_seqretry(&rename_lock, seq))
	221	goto rename_retry;
	222
	223	return len;
	224	}
	225
	226	static struct autofs_wait_queue *
	227	autofs_find_wait(struct autofs_sb_info sbi, const struct qstr qstr)
	228	{
	229	struct autofs_wait_queue *wq;
	230
	231	for (wq = sbi->queues; wq; wq = wq->next) {
	232	if (wq->name.hash == qstr->hash &&
	233	wq->name.len == qstr->len &&
	234	wq->name.name &&
	235	!memcmp(wq->name.name, qstr->name, qstr->len))
	236	break;
	237	}
	238	return wq;
	239	}
	240
	241	/*
	242	* Check if we have a valid request.
	243	* Returns
	244	* 1 if the request should continue.
	245	* In this case we can return an autofs_wait_queue entry if one is
	246	* found or NULL to idicate a new wait needs to be created.
	247	* 0 or a negative errno if the request shouldn't continue.
	248	*/
	249	static int validate_request(struct autofs_wait_queue **wait,
	250	struct autofs_sb_info *sbi,
	251	const struct qstr *qstr,
	252	const struct path *path, enum autofs_notify notify)
	253	{
	254	struct dentry *dentry = path->dentry;
	255	struct autofs_wait_queue *wq;
	256	struct autofs_info *ino;
257
9d8719a4	258	if (sbi->flags & AUTOFS_SBI_CATATONIC)
ebc921ca IK	259	return -ENOENT;
	260
	261	/* Wait in progress, continue; */
	262	wq = autofs_find_wait(sbi, qstr);
	263	if (wq) {
	264	*wait = wq;
	265	return 1;
	266	}
	267
	268	*wait = NULL;
	269
	270	/* If we don't yet have any info this is a new request */
	271	ino = autofs_dentry_ino(dentry);
	272	if (!ino)
	273	return 1;
	274
	275	/*
	276	* If we've been asked to wait on an existing expire (NFY_NONE)
	277	* but there is no wait in the queue ...
	278	*/
	279	if (notify == NFY_NONE) {
	280	/*
	281	* Either we've betean the pending expire to post it's
	282	* wait or it finished while we waited on the mutex.
	283	* So we need to wait till either, the wait appears
	284	* or the expire finishes.
	285	*/
	286
	287	while (ino->flags & AUTOFS_INF_EXPIRING) {
	288	mutex_unlock(&sbi->wq_mutex);
	289	schedule_timeout_interruptible(HZ/10);
	290	if (mutex_lock_interruptible(&sbi->wq_mutex))
	291	return -EINTR;
	292
9d8719a4	293	if (sbi->flags & AUTOFS_SBI_CATATONIC)
ebc921ca IK	294	return -ENOENT;
	295
	296	wq = autofs_find_wait(sbi, qstr);
	297	if (wq) {
	298	*wait = wq;
	299	return 1;
	300	}
	301	}
	302
	303	/*
	304	* Not ideal but the status has already gone. Of the two
	305	* cases where we wait on NFY_NONE neither depend on the
	306	* return status of the wait.
	307	*/
	308	return 0;
	309	}
	310
	311	/*
	312	* If we've been asked to trigger a mount and the request
	313	* completed while we waited on the mutex ...
	314	*/
	315	if (notify == NFY_MOUNT) {
	316	struct dentry *new = NULL;
	317	struct path this;
	318	int valid = 1;
	319
	320	/*
	321	* If the dentry was successfully mounted while we slept
	322	* on the wait queue mutex we can return success. If it
	323	* isn't mounted (doesn't have submounts for the case of
	324	* a multi-mount with no mount at it's base) we can
	325	* continue on and create a new request.
	326	*/
	327	if (!IS_ROOT(dentry)) {
	328	if (d_unhashed(dentry) &&
	329	d_really_is_positive(dentry)) {
	330	struct dentry *parent = dentry->d_parent;
	331
	332	new = d_lookup(parent, &dentry->d_name);
	333	if (new)
	334	dentry = new;
	335	}
	336	}
	337	this.mnt = path->mnt;
	338	this.dentry = dentry;
	339	if (path_has_submounts(&this))
	340	valid = 0;
	341
	342	if (new)
	343	dput(new);
	344	return valid;
	345	}
	346
	347	return 1;
	348	}
	349
	350	int autofs_wait(struct autofs_sb_info *sbi,
	351	const struct path *path, enum autofs_notify notify)
	352	{
	353	struct dentry *dentry = path->dentry;
	354	struct autofs_wait_queue *wq;
	355	struct qstr qstr;
	356	char *name;
	357	int status, ret, type;
358	pid_t pid;
359	pid_t tgid;
360
361	/* In catatonic mode, we don't wait for nobody */
9d8719a4	362	if (sbi->flags & AUTOFS_SBI_CATATONIC)
ebc921ca IK	363	return -ENOENT;
	364
	365	/*
	366	* Try translating pids to the namespace of the daemon.
	367	*
	368	* Zero means failure: we are in an unrelated pid namespace.
	369	*/
	370	pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
	371	tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
	372	if (pid == 0 \|\| tgid == 0)
	373	return -ENOENT;
	374
	375	if (d_really_is_negative(dentry)) {
	376	/*
	377	* A wait for a negative dentry is invalid for certain
	378	* cases. A direct or offset mount "always" has its mount
	379	* point directory created and so the request dentry must
	380	* be positive or the map key doesn't exist. The situation
	381	* is very similar for indirect mounts except only dentrys
	382	* in the root of the autofs file system may be negative.
	383	*/
	384	if (autofs_type_trigger(sbi->type))
	385	return -ENOENT;
	386	else if (!IS_ROOT(dentry->d_parent))
	387	return -ENOENT;
	388	}
	389
	390	name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
	391	if (!name)
	392	return -ENOMEM;
	393
	394	/* If this is a direct mount request create a dummy name */
	395	if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
	396	qstr.len = sprintf(name, "%p", dentry);
	397	else {
016e92da	398	qstr.len = autofs_getpath(sbi, dentry, name);
ebc921ca IK	399	if (!qstr.len) {
	400	kfree(name);
	401	return -ENOENT;
	402	}
	403	}
	404	qstr.name = name;
	405	qstr.hash = full_name_hash(dentry, name, qstr.len);
	406
	407	if (mutex_lock_interruptible(&sbi->wq_mutex)) {
	408	kfree(qstr.name);
	409	return -EINTR;
	410	}
	411
	412	ret = validate_request(&wq, sbi, &qstr, path, notify);
	413	if (ret <= 0) {
	414	if (ret != -EINTR)
	415	mutex_unlock(&sbi->wq_mutex);
	416	kfree(qstr.name);
	417	return ret;
	418	}
	419
	420	if (!wq) {
	421	/* Create a new wait queue */
	422	wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL);
	423	if (!wq) {
	424	kfree(qstr.name);
	425	mutex_unlock(&sbi->wq_mutex);
	426	return -ENOMEM;
	427	}
	428
	429	wq->wait_queue_token = autofs_next_wait_queue;
	430	if (++autofs_next_wait_queue == 0)
	431	autofs_next_wait_queue = 1;
	432	wq->next = sbi->queues;
	433	sbi->queues = wq;
	434	init_waitqueue_head(&wq->queue);
	435	memcpy(&wq->name, &qstr, sizeof(struct qstr));
	436	wq->dev = autofs_get_dev(sbi);
	437	wq->ino = autofs_get_ino(sbi);
	438	wq->uid = current_uid();
	439	wq->gid = current_gid();
	440	wq->pid = pid;
	441	wq->tgid = tgid;
	442	wq->status = -EINTR; /* Status return if interrupted */
	443	wq->wait_ctr = 2;
	444
	445	if (sbi->version < 5) {
	446	if (notify == NFY_MOUNT)
	447	type = autofs_ptype_missing;
	448	else
	449	type = autofs_ptype_expire_multi;
	450	} else {
	451	if (notify == NFY_MOUNT)
	452	type = autofs_type_trigger(sbi->type) ?
	453	autofs_ptype_missing_direct :
	454	autofs_ptype_missing_indirect;
	455	else
	456	type = autofs_type_trigger(sbi->type) ?
	457	autofs_ptype_expire_direct :
	458	autofs_ptype_expire_indirect;
	459	}
	460
	461	pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
	462	(unsigned long) wq->wait_queue_token, wq->name.len,
463	wq->name.name, notify);
464
465	/*
466	* autofs_notify_daemon() may block; it will unlock ->wq_mutex
467	*/
468	autofs_notify_daemon(sbi, wq, type);
469	} else {
470	wq->wait_ctr++;
471	pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
472	(unsigned long) wq->wait_queue_token, wq->name.len,
473	wq->name.name, notify);
474	mutex_unlock(&sbi->wq_mutex);
475	kfree(qstr.name);
476	}
477
478	/*
479	* wq->name.name is NULL iff the lock is already released
480	* or the mount has been made catatonic.
481	*/
482	wait_event_killable(wq->queue, wq->name.name == NULL);
483	status = wq->status;
484
485	/*
486	* For direct and offset mounts we need to track the requester's
487	* uid and gid in the dentry info struct. This is so it can be
488	* supplied, on request, by the misc device ioctl interface.
489	* This is needed during daemon resatart when reconnecting
490	* to existing, active, autofs mounts. The uid and gid (and
491	* related string values) may be used for macro substitution
492	* in autofs mount maps.
493	*/
494	if (!status) {
495	struct autofs_info *ino;
496	struct dentry *de = NULL;
497
498	/* direct mount or browsable map */
499	ino = autofs_dentry_ino(dentry);
500	if (!ino) {
501	/* If not lookup actual dentry used */
502	de = d_lookup(dentry->d_parent, &dentry->d_name);
503	if (de)
504	ino = autofs_dentry_ino(de);
505	}
506
507	/* Set mount requester */
508	if (ino) {
509	spin_lock(&sbi->fs_lock);
510	ino->uid = wq->uid;
511	ino->gid = wq->gid;
512	spin_unlock(&sbi->fs_lock);
513	}
514
515	if (de)
516	dput(de);
517	}
518
519	/* Are we the last process to need status? */
520	mutex_lock(&sbi->wq_mutex);
521	if (!--wq->wait_ctr)
522	kfree(wq);
523	mutex_unlock(&sbi->wq_mutex);
524
525	return status;
526	}
527
528
529	int autofs_wait_release(struct autofs_sb_info *sbi,
530	autofs_wqt_t wait_queue_token, int status)
531	{
532	struct autofs_wait_queue wq, *wql;
533
534	mutex_lock(&sbi->wq_mutex);
535	for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
536	if (wq->wait_queue_token == wait_queue_token)
537	break;
538	}
539
540	if (!wq) {
541	mutex_unlock(&sbi->wq_mutex);
542	return -EINVAL;
543	}
544
545	wql = wq->next; / Unlink from chain */
546	kfree(wq->name.name);
547	wq->name.name = NULL; /* Do not wait on this queue */
548	wq->status = status;
549	wake_up(&wq->queue);
550	if (!--wq->wait_ctr)
551	kfree(wq);
552	mutex_unlock(&sbi->wq_mutex);
553
554	return 0;
555	}