[thirdparty/linux.git] / fs / autofs / waitq.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
 */

#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
d6910058	1	// SPDX-License-Identifier: GPL-2.0-or-later
ebc921ca IK	2	/*
	3	* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
	4	* Copyright 2001-2006 Ian Kent <raven@themaw.net>
ebc921ca IK	5	*/
ebc921ca IK	6
ebc921ca	7	#include <linux/sched/signal.h>
ebc921ca IK	8	#include "autofs_i.h"
	9
	10	/* We make this a static variable rather than a part of the superblock; it
	11	* is better if we don't reassign numbers easily even across filesystems
	12	*/
	13	static autofs_wqt_t autofs_next_wait_queue = 1;
	14
	15	void autofs_catatonic_mode(struct autofs_sb_info *sbi)
	16	{
	17	struct autofs_wait_queue wq, nwq;
	18
	19	mutex_lock(&sbi->wq_mutex);
9d8719a4	20	if (sbi->flags & AUTOFS_SBI_CATATONIC) {
ebc921ca IK	21	mutex_unlock(&sbi->wq_mutex);
	22	return;
	23	}
	24
	25	pr_debug("entering catatonic mode\n");
	26
9d8719a4	27	sbi->flags \|= AUTOFS_SBI_CATATONIC;
ebc921ca IK	28	wq = sbi->queues;
	29	sbi->queues = NULL; /* Erase all wait queues */
	30	while (wq) {
	31	nwq = wq->next;
	32	wq->status = -ENOENT; /* Magic is gone - report failure */
	33	kfree(wq->name.name);
	34	wq->name.name = NULL;
	35	wq->wait_ctr--;
	36	wake_up_interruptible(&wq->queue);
	37	wq = nwq;
	38	}
	39	fput(sbi->pipe); /* Close the pipe */
	40	sbi->pipe = NULL;
	41	sbi->pipefd = -1;
	42	mutex_unlock(&sbi->wq_mutex);
	43	}
	44
	45	static int autofs_write(struct autofs_sb_info *sbi,
	46	struct file file, const void addr, int bytes)
	47	{
	48	unsigned long sigpipe, flags;
	49	const char data = (const char )addr;
	50	ssize_t wr = 0;
	51
	52	sigpipe = sigismember(&current->pending.signal, SIGPIPE);
	53
	54	mutex_lock(&sbi->pipe_mutex);
	55	while (bytes) {
	56	wr = __kernel_write(file, data, bytes, &file->f_pos);
	57	if (wr <= 0)
	58	break;
	59	data += wr;
	60	bytes -= wr;
	61	}
	62	mutex_unlock(&sbi->pipe_mutex);
	63
	64	/* Keep the currently executing process from receiving a
	65	* SIGPIPE unless it was already supposed to get one
	66	*/
	67	if (wr == -EPIPE && !sigpipe) {
	68	spin_lock_irqsave(&current->sighand->siglock, flags);
	69	sigdelset(&current->pending.signal, SIGPIPE);
	70	recalc_sigpending();
	71	spin_unlock_irqrestore(&current->sighand->siglock, flags);
	72	}
	73
	74	/* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
	75	return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
	76	}
	77
	78	static void autofs_notify_daemon(struct autofs_sb_info *sbi,
	79	struct autofs_wait_queue *wq,
	80	int type)
	81	{
	82	union {
	83	struct autofs_packet_hdr hdr;
	84	union autofs_packet_union v4_pkt;
	85	union autofs_v5_packet_union v5_pkt;
	86	} pkt;
	87	struct file *pipe = NULL;
	88	size_t pktsz;
	89	int ret;
	90
	91	pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n",
92	(unsigned long) wq->wait_queue_token,
93	wq->name.len, wq->name.name, type);
94
95	memset(&pkt, 0, sizeof(pkt)); /* For security reasons */
96
97	pkt.hdr.proto_version = sbi->version;
98	pkt.hdr.type = type;
99
100	switch (type) {
101	/* Kernel protocol v4 missing and expire packets */
102	case autofs_ptype_missing:
103	{
104	struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
105
106	pktsz = sizeof(*mp);
107
108	mp->wait_queue_token = wq->wait_queue_token;
109	mp->len = wq->name.len;
110	memcpy(mp->name, wq->name.name, wq->name.len);
111	mp->name[wq->name.len] = '\0';
112	break;
113	}
114	case autofs_ptype_expire_multi:
115	{
116	struct autofs_packet_expire_multi *ep =
117	&pkt.v4_pkt.expire_multi;
118
119	pktsz = sizeof(*ep);
120
121	ep->wait_queue_token = wq->wait_queue_token;
122	ep->len = wq->name.len;
123	memcpy(ep->name, wq->name.name, wq->name.len);
124	ep->name[wq->name.len] = '\0';
125	break;
126	}
127	/*
128	* Kernel protocol v5 packet for handling indirect and direct
129	* mount missing and expire requests
130	*/
131	case autofs_ptype_missing_indirect:
132	case autofs_ptype_expire_indirect:
133	case autofs_ptype_missing_direct:
134	case autofs_ptype_expire_direct:
135	{
136	struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
137	struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
138
139	pktsz = sizeof(*packet);
140
141	packet->wait_queue_token = wq->wait_queue_token;
142	packet->len = wq->name.len;
143	memcpy(packet->name, wq->name.name, wq->name.len);
144	packet->name[wq->name.len] = '\0';
145	packet->dev = wq->dev;
146	packet->ino = wq->ino;
147	packet->uid = from_kuid_munged(user_ns, wq->uid);
148	packet->gid = from_kgid_munged(user_ns, wq->gid);
149	packet->pid = wq->pid;
150	packet->tgid = wq->tgid;
151	break;
152	}
153	default:
154	pr_warn("bad type %d!\n", type);
155	mutex_unlock(&sbi->wq_mutex);
156	return;
157	}
158
159	pipe = get_file(sbi->pipe);
160
161	mutex_unlock(&sbi->wq_mutex);
162
163	switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) {
164	case 0:
165	break;
166	case -ENOMEM:
167	case -ERESTARTSYS:
168	/* Just fail this one */
169	autofs_wait_release(sbi, wq->wait_queue_token, ret);
170	break;
171	default:
172	autofs_catatonic_mode(sbi);
173	break;
174	}
175	fput(pipe);
176	}
177
178	static int autofs_getpath(struct autofs_sb_info *sbi,
016e92da	179	struct dentry dentry, char name)
ebc921ca IK	180	{
	181	struct dentry *root = sbi->sb->s_root;
	182	struct dentry *tmp;
	183	char *buf;
	184	char *p;
	185	int len;
	186	unsigned seq;
	187
	188	rename_retry:
016e92da	189	buf = name;
ebc921ca IK	190	len = 0;
	191
	192	seq = read_seqbegin(&rename_lock);
	193	rcu_read_lock();
	194	spin_lock(&sbi->fs_lock);
	195	for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
	196	len += tmp->d_name.len + 1;
	197
	198	if (!len \|\| --len > NAME_MAX) {
	199	spin_unlock(&sbi->fs_lock);
	200	rcu_read_unlock();
	201	if (read_seqretry(&rename_lock, seq))
	202	goto rename_retry;
	203	return 0;
	204	}
	205
	206	*(buf + len) = '\0';
	207	p = buf + len - dentry->d_name.len;
	208	strncpy(p, dentry->d_name.name, dentry->d_name.len);
	209
	210	for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
	211	*(--p) = '/';
	212	p -= tmp->d_name.len;
	213	strncpy(p, tmp->d_name.name, tmp->d_name.len);
	214	}
	215	spin_unlock(&sbi->fs_lock);
	216	rcu_read_unlock();
	217	if (read_seqretry(&rename_lock, seq))
	218	goto rename_retry;
	219
	220	return len;
	221	}
	222
	223	static struct autofs_wait_queue *
	224	autofs_find_wait(struct autofs_sb_info sbi, const struct qstr qstr)
	225	{
	226	struct autofs_wait_queue *wq;
	227
	228	for (wq = sbi->queues; wq; wq = wq->next) {
	229	if (wq->name.hash == qstr->hash &&
	230	wq->name.len == qstr->len &&
	231	wq->name.name &&
	232	!memcmp(wq->name.name, qstr->name, qstr->len))
	233	break;
	234	}
	235	return wq;
	236	}
	237
	238	/*
	239	* Check if we have a valid request.
	240	* Returns
	241	* 1 if the request should continue.
	242	* In this case we can return an autofs_wait_queue entry if one is
	243	* found or NULL to idicate a new wait needs to be created.
	244	* 0 or a negative errno if the request shouldn't continue.
	245	*/
	246	static int validate_request(struct autofs_wait_queue **wait,
	247	struct autofs_sb_info *sbi,
	248	const struct qstr *qstr,
	249	const struct path *path, enum autofs_notify notify)
	250	{
	251	struct dentry *dentry = path->dentry;
	252	struct autofs_wait_queue *wq;
	253	struct autofs_info *ino;
254
9d8719a4	255	if (sbi->flags & AUTOFS_SBI_CATATONIC)
ebc921ca IK	256	return -ENOENT;
	257
	258	/* Wait in progress, continue; */
	259	wq = autofs_find_wait(sbi, qstr);
	260	if (wq) {
	261	*wait = wq;
	262	return 1;
	263	}
	264
	265	*wait = NULL;
	266
	267	/* If we don't yet have any info this is a new request */
	268	ino = autofs_dentry_ino(dentry);
	269	if (!ino)
	270	return 1;
	271
	272	/*
	273	* If we've been asked to wait on an existing expire (NFY_NONE)
	274	* but there is no wait in the queue ...
	275	*/
	276	if (notify == NFY_NONE) {
	277	/*
	278	* Either we've betean the pending expire to post it's
	279	* wait or it finished while we waited on the mutex.
	280	* So we need to wait till either, the wait appears
	281	* or the expire finishes.
	282	*/
	283
	284	while (ino->flags & AUTOFS_INF_EXPIRING) {
	285	mutex_unlock(&sbi->wq_mutex);
	286	schedule_timeout_interruptible(HZ/10);
	287	if (mutex_lock_interruptible(&sbi->wq_mutex))
	288	return -EINTR;
	289
9d8719a4	290	if (sbi->flags & AUTOFS_SBI_CATATONIC)
ebc921ca IK	291	return -ENOENT;
	292
	293	wq = autofs_find_wait(sbi, qstr);
	294	if (wq) {
	295	*wait = wq;
	296	return 1;
	297	}
	298	}
	299
	300	/*
	301	* Not ideal but the status has already gone. Of the two
	302	* cases where we wait on NFY_NONE neither depend on the
	303	* return status of the wait.
	304	*/
	305	return 0;
	306	}
	307
	308	/*
	309	* If we've been asked to trigger a mount and the request
	310	* completed while we waited on the mutex ...
	311	*/
	312	if (notify == NFY_MOUNT) {
	313	struct dentry *new = NULL;
	314	struct path this;
	315	int valid = 1;
	316
	317	/*
	318	* If the dentry was successfully mounted while we slept
	319	* on the wait queue mutex we can return success. If it
	320	* isn't mounted (doesn't have submounts for the case of
	321	* a multi-mount with no mount at it's base) we can
	322	* continue on and create a new request.
	323	*/
	324	if (!IS_ROOT(dentry)) {
	325	if (d_unhashed(dentry) &&
	326	d_really_is_positive(dentry)) {
	327	struct dentry *parent = dentry->d_parent;
	328
	329	new = d_lookup(parent, &dentry->d_name);
	330	if (new)
	331	dentry = new;
	332	}
	333	}
	334	this.mnt = path->mnt;
	335	this.dentry = dentry;
	336	if (path_has_submounts(&this))
	337	valid = 0;
	338
	339	if (new)
	340	dput(new);
	341	return valid;
	342	}
	343
	344	return 1;
	345	}
	346
	347	int autofs_wait(struct autofs_sb_info *sbi,
	348	const struct path *path, enum autofs_notify notify)
	349	{
	350	struct dentry *dentry = path->dentry;
	351	struct autofs_wait_queue *wq;
	352	struct qstr qstr;
	353	char *name;
	354	int status, ret, type;
355	pid_t pid;
356	pid_t tgid;
357
358	/* In catatonic mode, we don't wait for nobody */
9d8719a4	359	if (sbi->flags & AUTOFS_SBI_CATATONIC)
ebc921ca IK	360	return -ENOENT;
	361
	362	/*
	363	* Try translating pids to the namespace of the daemon.
	364	*
	365	* Zero means failure: we are in an unrelated pid namespace.
	366	*/
	367	pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
	368	tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
	369	if (pid == 0 \|\| tgid == 0)
	370	return -ENOENT;
	371
	372	if (d_really_is_negative(dentry)) {
	373	/*
	374	* A wait for a negative dentry is invalid for certain
	375	* cases. A direct or offset mount "always" has its mount
	376	* point directory created and so the request dentry must
	377	* be positive or the map key doesn't exist. The situation
	378	* is very similar for indirect mounts except only dentrys
	379	* in the root of the autofs file system may be negative.
	380	*/
	381	if (autofs_type_trigger(sbi->type))
	382	return -ENOENT;
	383	else if (!IS_ROOT(dentry->d_parent))
	384	return -ENOENT;
	385	}
	386
	387	name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
	388	if (!name)
	389	return -ENOMEM;
	390
	391	/* If this is a direct mount request create a dummy name */
	392	if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
	393	qstr.len = sprintf(name, "%p", dentry);
	394	else {
016e92da	395	qstr.len = autofs_getpath(sbi, dentry, name);
ebc921ca IK	396	if (!qstr.len) {
	397	kfree(name);
	398	return -ENOENT;
	399	}
	400	}
	401	qstr.name = name;
	402	qstr.hash = full_name_hash(dentry, name, qstr.len);
	403
	404	if (mutex_lock_interruptible(&sbi->wq_mutex)) {
	405	kfree(qstr.name);
	406	return -EINTR;
	407	}
	408
	409	ret = validate_request(&wq, sbi, &qstr, path, notify);
	410	if (ret <= 0) {
	411	if (ret != -EINTR)
	412	mutex_unlock(&sbi->wq_mutex);
	413	kfree(qstr.name);
	414	return ret;
	415	}
	416
	417	if (!wq) {
	418	/* Create a new wait queue */
	419	wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL);
	420	if (!wq) {
	421	kfree(qstr.name);
	422	mutex_unlock(&sbi->wq_mutex);
	423	return -ENOMEM;
	424	}
	425
	426	wq->wait_queue_token = autofs_next_wait_queue;
	427	if (++autofs_next_wait_queue == 0)
	428	autofs_next_wait_queue = 1;
	429	wq->next = sbi->queues;
	430	sbi->queues = wq;
	431	init_waitqueue_head(&wq->queue);
	432	memcpy(&wq->name, &qstr, sizeof(struct qstr));
	433	wq->dev = autofs_get_dev(sbi);
	434	wq->ino = autofs_get_ino(sbi);
	435	wq->uid = current_uid();
	436	wq->gid = current_gid();
	437	wq->pid = pid;
	438	wq->tgid = tgid;
	439	wq->status = -EINTR; /* Status return if interrupted */
	440	wq->wait_ctr = 2;
	441
	442	if (sbi->version < 5) {
	443	if (notify == NFY_MOUNT)
	444	type = autofs_ptype_missing;
	445	else
	446	type = autofs_ptype_expire_multi;
	447	} else {
	448	if (notify == NFY_MOUNT)
	449	type = autofs_type_trigger(sbi->type) ?
	450	autofs_ptype_missing_direct :
	451	autofs_ptype_missing_indirect;
	452	else
	453	type = autofs_type_trigger(sbi->type) ?
	454	autofs_ptype_expire_direct :
	455	autofs_ptype_expire_indirect;
	456	}
	457
	458	pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
	459	(unsigned long) wq->wait_queue_token, wq->name.len,
460	wq->name.name, notify);
461
462	/*
463	* autofs_notify_daemon() may block; it will unlock ->wq_mutex
464	*/
465	autofs_notify_daemon(sbi, wq, type);
466	} else {
467	wq->wait_ctr++;
468	pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
469	(unsigned long) wq->wait_queue_token, wq->name.len,
470	wq->name.name, notify);
471	mutex_unlock(&sbi->wq_mutex);
472	kfree(qstr.name);
473	}
474
475	/*
476	* wq->name.name is NULL iff the lock is already released
477	* or the mount has been made catatonic.
478	*/
479	wait_event_killable(wq->queue, wq->name.name == NULL);
480	status = wq->status;
481
482	/*
483	* For direct and offset mounts we need to track the requester's
484	* uid and gid in the dentry info struct. This is so it can be
485	* supplied, on request, by the misc device ioctl interface.
486	* This is needed during daemon resatart when reconnecting
487	* to existing, active, autofs mounts. The uid and gid (and
488	* related string values) may be used for macro substitution
489	* in autofs mount maps.
490	*/
491	if (!status) {
492	struct autofs_info *ino;
493	struct dentry *de = NULL;
494
495	/* direct mount or browsable map */
496	ino = autofs_dentry_ino(dentry);
497	if (!ino) {
498	/* If not lookup actual dentry used */
499	de = d_lookup(dentry->d_parent, &dentry->d_name);
500	if (de)
501	ino = autofs_dentry_ino(de);
502	}
503
504	/* Set mount requester */
505	if (ino) {
506	spin_lock(&sbi->fs_lock);
507	ino->uid = wq->uid;
508	ino->gid = wq->gid;
509	spin_unlock(&sbi->fs_lock);
510	}
511
512	if (de)
513	dput(de);
514	}
515
516	/* Are we the last process to need status? */
517	mutex_lock(&sbi->wq_mutex);
518	if (!--wq->wait_ctr)
519	kfree(wq);
520	mutex_unlock(&sbi->wq_mutex);
521
522	return status;
523	}
524
525
526	int autofs_wait_release(struct autofs_sb_info *sbi,
527	autofs_wqt_t wait_queue_token, int status)
528	{
529	struct autofs_wait_queue wq, *wql;
530
531	mutex_lock(&sbi->wq_mutex);
532	for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
533	if (wq->wait_queue_token == wait_queue_token)
534	break;
535	}
536
537	if (!wq) {
538	mutex_unlock(&sbi->wq_mutex);
539	return -EINVAL;
540	}
541
542	wql = wq->next; / Unlink from chain */
543	kfree(wq->name.name);
544	wq->name.name = NULL; /* Do not wait on this queue */
545	wq->status = status;
546	wake_up(&wq->queue);
547	if (!--wq->wait_ctr)
548	kfree(wq);
549	mutex_unlock(&sbi->wq_mutex);
550
551	return 0;
552	}