[deliverable/linux.git] / fs / afs / mntpt.c

/* mountpoint management
 *
 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/mnt_namespace.h>
#include "internal.h"


static struct dentry *afs_mntpt_lookup(struct inode *dir,
				       struct dentry *dentry,
				       struct nameidata *nd);
static int afs_mntpt_open(struct inode *inode, struct file *file);
static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
static void afs_mntpt_expiry_timed_out(struct work_struct *work);

const struct file_operations afs_mntpt_file_operations = {
	.open		= afs_mntpt_open,
};

const struct inode_operations afs_mntpt_inode_operations = {
	.lookup		= afs_mntpt_lookup,
	.follow_link	= afs_mntpt_follow_link,
	.readlink	= page_readlink,
	.getattr	= afs_inode_getattr,
};

static LIST_HEAD(afs_vfsmounts);
static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);

unsigned long afs_mntpt_expiry_timeout = 10 * 60;

/*
 * check a symbolic link to see whether it actually encodes a mountpoint
 * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
 */
int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key)
{
	struct file file = {
		.private_data = key,
	};
	struct page *page;
	size_t size;
	char *buf;
	int ret;

	_enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique);

	/* read the contents of the symlink into the pagecache */
	page = read_mapping_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, &file);
	if (IS_ERR(page)) {
		ret = PTR_ERR(page);
		goto out;
	}

	ret = -EIO;
	if (PageError(page))
		goto out_free;

	buf = kmap(page);

	/* examine the symlink's contents */
	size = vnode->status.size;
	_debug("symlink to %*.*s", (int) size, (int) size, buf);

	if (size > 2 &&
	    (buf[0] == '%' || buf[0] == '#') &&
	    buf[size - 1] == '.'
	    ) {
		_debug("symlink is a mountpoint");
		spin_lock(&vnode->lock);
		set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
		spin_unlock(&vnode->lock);
	}

	ret = 0;

	kunmap(page);
out_free:
	page_cache_release(page);
out:
	_leave(" = %d", ret);
	return ret;
}

/*
 * no valid lookup procedure on this sort of dir
 */
static struct dentry *afs_mntpt_lookup(struct inode *dir,
				       struct dentry *dentry,
				       struct nameidata *nd)
{
	_enter("%p,%p{%p{%s},%s}",
	       dir,
	       dentry,
	       dentry->d_parent,
	       dentry->d_parent ?
	       dentry->d_parent->d_name.name : (const unsigned char *) "",
	       dentry->d_name.name);

	return ERR_PTR(-EREMOTE);
}

/*
 * no valid open procedure on this sort of dir
 */
static int afs_mntpt_open(struct inode *inode, struct file *file)
{
	_enter("%p,%p{%p{%s},%s}",
	       inode, file,
	       file->f_path.dentry->d_parent,
	       file->f_path.dentry->d_parent ?
	       file->f_path.dentry->d_parent->d_name.name :
	       (const unsigned char *) "",
	       file->f_path.dentry->d_name.name);

	return -EREMOTE;
}

/*
 * create a vfsmount to be automounted
 */
static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
{
	struct afs_super_info *super;
	struct vfsmount *mnt;
	struct page *page = NULL;
	size_t size;
	char *buf, *devname = NULL, *options = NULL;
	int ret;

	_enter("{%s}", mntpt->d_name.name);

	BUG_ON(!mntpt->d_inode);

	ret = -EINVAL;
	size = mntpt->d_inode->i_size;
	if (size > PAGE_SIZE - 1)
		goto error;

	ret = -ENOMEM;
	devname = (char *) get_zeroed_page(GFP_KERNEL);
	if (!devname)
		goto error;

	options = (char *) get_zeroed_page(GFP_KERNEL);
	if (!options)
		goto error;

	/* read the contents of the AFS special symlink */
	page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
	if (IS_ERR(page)) {
		ret = PTR_ERR(page);
		goto error;
	}

	ret = -EIO;
	if (PageError(page))
		goto error;

	buf = kmap(page);
	memcpy(devname, buf, size);
	kunmap(page);
	page_cache_release(page);
	page = NULL;

	/* work out what options we want */
	super = AFS_FS_S(mntpt->d_sb);
	memcpy(options, "cell=", 5);
	strcpy(options + 5, super->volume->cell->name);
	if (super->volume->type == AFSVL_RWVOL)
		strcat(options, ",rwpath");

	/* try and do the mount */
	_debug("--- attempting mount %s -o %s ---", devname, options);
	mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
	_debug("--- mount result %p ---", mnt);

	free_page((unsigned long) devname);
	free_page((unsigned long) options);
	_leave(" = %p", mnt);
	return mnt;

error:
	if (page)
		page_cache_release(page);
	if (devname)
		free_page((unsigned long) devname);
	if (options)
		free_page((unsigned long) options);
	_leave(" = %d", ret);
	return ERR_PTR(ret);
}

/*
 * follow a link from a mountpoint directory, thus causing it to be mounted
 */
static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	struct vfsmount *newmnt;
	int err;

	_enter("%p{%s},{%s:%p{%s},}",
	       dentry,
	       dentry->d_name.name,
	       nd->mnt->mnt_devname,
	       dentry,
	       nd->dentry->d_name.name);

	dput(nd->dentry);
	nd->dentry = dget(dentry);

	newmnt = afs_mntpt_do_automount(nd->dentry);
	if (IS_ERR(newmnt)) {
		path_release(nd);
		return (void *)newmnt;
	}

	mntget(newmnt);
	err = do_add_mount(newmnt, nd, MNT_SHRINKABLE, &afs_vfsmounts);
	switch (err) {
	case 0:
		mntput(nd->mnt);
		dput(nd->dentry);
		nd->mnt = newmnt;
		nd->dentry = dget(newmnt->mnt_root);
		schedule_delayed_work(&afs_mntpt_expiry_timer,
				      afs_mntpt_expiry_timeout * HZ);
		break;
	case -EBUSY:
		/* someone else made a mount here whilst we were busy */
		while (d_mountpoint(nd->dentry) &&
		       follow_down(&nd->mnt, &nd->dentry))
			;
		err = 0;
	default:
		mntput(newmnt);
		break;
	}

	_leave(" = %d", err);
	return ERR_PTR(err);
}

/*
 * handle mountpoint expiry timer going off
 */
static void afs_mntpt_expiry_timed_out(struct work_struct *work)
{
	_enter("");

	if (!list_empty(&afs_vfsmounts)) {
		mark_mounts_for_expiry(&afs_vfsmounts);
		schedule_delayed_work(&afs_mntpt_expiry_timer,
				      afs_mntpt_expiry_timeout * HZ);
	}

	_leave("");
}

/*
 * kill the AFS mountpoint timer if it's still running
 */
void afs_mntpt_kill_timer(void)
{
	_enter("");

	ASSERT(list_empty(&afs_vfsmounts));
	cancel_delayed_work(&afs_mntpt_expiry_timer);
	flush_scheduled_work();
}

/*
 * begin unmount by attempting to remove all automounted mountpoints we added
 */
void afs_umount_begin(struct vfsmount *vfsmnt, int flags)
{
	shrink_submounts(vfsmnt, &afs_vfsmounts);
}
Commit	Line	Data
ec26815a	1	/* mountpoint management
1da177e4 LT	2	*
	3	* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/kernel.h>
	13	#include <linux/module.h>
	14	#include <linux/init.h>
1da177e4 LT	15	#include <linux/slab.h>
	16	#include <linux/fs.h>
	17	#include <linux/pagemap.h>
	18	#include <linux/mount.h>
	19	#include <linux/namei.h>
6b3286ed	20	#include <linux/mnt_namespace.h>
1da177e4 LT	21	#include "internal.h"
	22
	23
	24	static struct dentry afs_mntpt_lookup(struct inode dir,
	25	struct dentry *dentry,
	26	struct nameidata *nd);
	27	static int afs_mntpt_open(struct inode inode, struct file file);
008b150a	28	static void afs_mntpt_follow_link(struct dentry dentry, struct nameidata *nd);
08e0e7c8	29	static void afs_mntpt_expiry_timed_out(struct work_struct *work);
1da177e4	30
4b6f5d20	31	const struct file_operations afs_mntpt_file_operations = {
1da177e4 LT	32	.open = afs_mntpt_open,
	33	};
	34
754661f1	35	const struct inode_operations afs_mntpt_inode_operations = {
1da177e4 LT	36	.lookup = afs_mntpt_lookup,
	37	.follow_link = afs_mntpt_follow_link,
	38	.readlink = page_readlink,
	39	.getattr = afs_inode_getattr,
	40	};
	41
	42	static LIST_HEAD(afs_vfsmounts);
08e0e7c8	43	static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
1da177e4	44
08e0e7c8	45	unsigned long afs_mntpt_expiry_timeout = 10 * 60;
1da177e4	46
1da177e4 LT	47	/*
	48	* check a symbolic link to see whether it actually encodes a mountpoint
	49	* - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
	50	*/
00d3b7a4	51	int afs_mntpt_check_symlink(struct afs_vnode vnode, struct key key)
1da177e4	52	{
00d3b7a4 DH	53	struct file file = {
	54	.private_data = key,
	55	};
1da177e4	56	struct page *page;
1da177e4 LT	57	size_t size;
	58	char *buf;
	59	int ret;
	60
	61	_enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique);
	62
	63	/* read the contents of the symlink into the pagecache */
00d3b7a4	64	page = read_mapping_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, &file);
1da177e4 LT	65	if (IS_ERR(page)) {
	66	ret = PTR_ERR(page);
	67	goto out;
	68	}
	69
	70	ret = -EIO;
1da177e4 LT	71	if (PageError(page))
	72	goto out_free;
	73
6fe6900e NP	74	buf = kmap(page);
6fe6900e NP	75
1da177e4 LT	76	/* examine the symlink's contents */
1da177e4 LT	77	size = vnode->status.size;
08e0e7c8	78	_debug("symlink to %.s", (int) size, (int) size, buf);
1da177e4 LT	79
	80	if (size > 2 &&
	81	(buf[0] == '%' \|\| buf[0] == '#') &&
	82	buf[size - 1] == '.'
	83	) {
	84	_debug("symlink is a mountpoint");
	85	spin_lock(&vnode->lock);
08e0e7c8	86	set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
1da177e4 LT	87	spin_unlock(&vnode->lock);
	88	}
	89
	90	ret = 0;
	91
1da177e4	92	kunmap(page);
6fe6900e	93	out_free:
1da177e4	94	page_cache_release(page);
ec26815a	95	out:
1da177e4 LT	96	_leave(" = %d", ret);
1da177e4 LT	97	return ret;
ec26815a	98	}
1da177e4	99
1da177e4 LT	100	/*
	101	* no valid lookup procedure on this sort of dir
	102	*/
	103	static struct dentry afs_mntpt_lookup(struct inode dir,
	104	struct dentry *dentry,
	105	struct nameidata *nd)
	106	{
08e0e7c8	107	_enter("%p,%p{%p{%s},%s}",
1da177e4 LT	108	dir,
	109	dentry,
	110	dentry->d_parent,
	111	dentry->d_parent ?
	112	dentry->d_parent->d_name.name : (const unsigned char *) "",
	113	dentry->d_name.name);
	114
	115	return ERR_PTR(-EREMOTE);
ec26815a	116	}
1da177e4	117
1da177e4 LT	118	/*
	119	* no valid open procedure on this sort of dir
	120	*/
	121	static int afs_mntpt_open(struct inode inode, struct file file)
	122	{
08e0e7c8	123	_enter("%p,%p{%p{%s},%s}",
1da177e4	124	inode, file,
1d56a969 JS	125	file->f_path.dentry->d_parent,
	126	file->f_path.dentry->d_parent ?
	127	file->f_path.dentry->d_parent->d_name.name :
1da177e4	128	(const unsigned char *) "",
1d56a969	129	file->f_path.dentry->d_name.name);
1da177e4 LT	130
1da177e4 LT	131	return -EREMOTE;
ec26815a	132	}
1da177e4	133
1da177e4 LT	134	/*
	135	* create a vfsmount to be automounted
	136	*/
	137	static struct vfsmount afs_mntpt_do_automount(struct dentry mntpt)
	138	{
	139	struct afs_super_info *super;
	140	struct vfsmount *mnt;
	141	struct page *page = NULL;
	142	size_t size;
	143	char buf, devname = NULL, *options = NULL;
1da177e4 LT	144	int ret;
1da177e4 LT	145
08e0e7c8	146	_enter("{%s}", mntpt->d_name.name);
1da177e4 LT	147
	148	BUG_ON(!mntpt->d_inode);
	149
	150	ret = -EINVAL;
	151	size = mntpt->d_inode->i_size;
	152	if (size > PAGE_SIZE - 1)
	153	goto error;
	154
	155	ret = -ENOMEM;
	156	devname = (char *) get_zeroed_page(GFP_KERNEL);
	157	if (!devname)
	158	goto error;
	159
	160	options = (char *) get_zeroed_page(GFP_KERNEL);
	161	if (!options)
	162	goto error;
	163
	164	/* read the contents of the AFS special symlink */
090d2b18	165	page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
1da177e4 LT	166	if (IS_ERR(page)) {
	167	ret = PTR_ERR(page);
	168	goto error;
	169	}
	170
	171	ret = -EIO;
6fe6900e	172	if (PageError(page))
1da177e4 LT	173	goto error;
	174
	175	buf = kmap(page);
	176	memcpy(devname, buf, size);
	177	kunmap(page);
	178	page_cache_release(page);
	179	page = NULL;
	180
	181	/* work out what options we want */
	182	super = AFS_FS_S(mntpt->d_sb);
	183	memcpy(options, "cell=", 5);
	184	strcpy(options + 5, super->volume->cell->name);
	185	if (super->volume->type == AFSVL_RWVOL)
	186	strcat(options, ",rwpath");
	187
	188	/* try and do the mount */
08e0e7c8	189	_debug("--- attempting mount %s -o %s ---", devname, options);
1f5ce9e9	190	mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
08e0e7c8	191	_debug("--- mount result %p ---", mnt);
1da177e4 LT	192
	193	free_page((unsigned long) devname);
	194	free_page((unsigned long) options);
08e0e7c8	195	_leave(" = %p", mnt);
1da177e4 LT	196	return mnt;
1da177e4 LT	197
ec26815a	198	error:
1da177e4 LT	199	if (page)
	200	page_cache_release(page);
	201	if (devname)
	202	free_page((unsigned long) devname);
	203	if (options)
	204	free_page((unsigned long) options);
08e0e7c8	205	_leave(" = %d", ret);
1da177e4	206	return ERR_PTR(ret);
ec26815a	207	}
1da177e4	208
1da177e4 LT	209	/*
	210	* follow a link from a mountpoint directory, thus causing it to be mounted
	211	*/
008b150a	212	static void afs_mntpt_follow_link(struct dentry dentry, struct nameidata *nd)
1da177e4 LT	213	{
1da177e4 LT	214	struct vfsmount *newmnt;
1da177e4 LT	215	int err;
1da177e4 LT	216
00d3b7a4	217	_enter("%p{%s},{%s:%p{%s},}",
1da177e4 LT	218	dentry,
	219	dentry->d_name.name,
	220	nd->mnt->mnt_devname,
	221	dentry,
	222	nd->dentry->d_name.name);
	223
08e0e7c8 DH	224	dput(nd->dentry);
	225	nd->dentry = dget(dentry);
	226
	227	newmnt = afs_mntpt_do_automount(nd->dentry);
1da177e4 LT	228	if (IS_ERR(newmnt)) {
1da177e4 LT	229	path_release(nd);
008b150a	230	return (void *)newmnt;
1da177e4 LT	231	}
1da177e4 LT	232
08e0e7c8 DH	233	mntget(newmnt);
	234	err = do_add_mount(newmnt, nd, MNT_SHRINKABLE, &afs_vfsmounts);
	235	switch (err) {
	236	case 0:
00d3b7a4 DH	237	mntput(nd->mnt);
00d3b7a4 DH	238	dput(nd->dentry);
1da177e4	239	nd->mnt = newmnt;
08e0e7c8 DH	240	nd->dentry = dget(newmnt->mnt_root);
	241	schedule_delayed_work(&afs_mntpt_expiry_timer,
	242	afs_mntpt_expiry_timeout * HZ);
	243	break;
	244	case -EBUSY:
	245	/* someone else made a mount here whilst we were busy */
	246	while (d_mountpoint(nd->dentry) &&
	247	follow_down(&nd->mnt, &nd->dentry))
	248	;
	249	err = 0;
	250	default:
	251	mntput(newmnt);
	252	break;
1da177e4 LT	253	}
1da177e4 LT	254
08e0e7c8	255	_leave(" = %d", err);
008b150a	256	return ERR_PTR(err);
ec26815a	257	}
1da177e4	258
1da177e4 LT	259	/*
	260	* handle mountpoint expiry timer going off
	261	*/
08e0e7c8	262	static void afs_mntpt_expiry_timed_out(struct work_struct *work)
1da177e4	263	{
08e0e7c8 DH	264	_enter("");
	265
	266	if (!list_empty(&afs_vfsmounts)) {
	267	mark_mounts_for_expiry(&afs_vfsmounts);
	268	schedule_delayed_work(&afs_mntpt_expiry_timer,
	269	afs_mntpt_expiry_timeout * HZ);
	270	}
	271
	272	_leave("");
	273	}
1da177e4	274
08e0e7c8 DH	275	/*
	276	* kill the AFS mountpoint timer if it's still running
	277	*/
	278	void afs_mntpt_kill_timer(void)
	279	{
	280	_enter("");
1da177e4	281
08e0e7c8 DH	282	ASSERT(list_empty(&afs_vfsmounts));
	283	cancel_delayed_work(&afs_mntpt_expiry_timer);
	284	flush_scheduled_work();
	285	}
1da177e4	286
08e0e7c8 DH	287	/*
	288	* begin unmount by attempting to remove all automounted mountpoints we added
	289	*/
	290	void afs_umount_begin(struct vfsmount *vfsmnt, int flags)
	291	{
	292	shrink_submounts(vfsmnt, &afs_vfsmounts);
ec26815a	293	}