fs/autofs4/waitq.c - linux - Git at Google

 /* -*- 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;
 }
	/* -- 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;
	}