[net-next-2.6.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/fs.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/gfp.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,
	.llseek		= noop_llseek,
};

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

const struct inode_operations afs_autocell_inode_operations = {
	.follow_link	= afs_mntpt_follow_link,
	.getattr	= afs_getattr,
};

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

static 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 page *page;
	size_t size;
	char *buf;
	int ret;

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

	/* read the contents of the symlink into the pagecache */
	page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
			       afs_page_filler, key);
	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 afs_vnode *vnode;
	struct page *page;
	char *devname, *options;
	bool rwpath = false;
	int ret;

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

	BUG_ON(!mntpt->d_inode);

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

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

	vnode = AFS_FS_I(mntpt->d_inode);
	if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
		/* if the directory is a pseudo directory, use the d_name */
		static const char afs_root_cell[] = ":root.cell.";
		unsigned size = mntpt->d_name.len;

		ret = -ENOENT;
		if (size < 2 || size > AFS_MAXCELLNAME)
			goto error_no_page;

		if (mntpt->d_name.name[0] == '.') {
			devname[0] = '#';
			memcpy(devname + 1, mntpt->d_name.name, size - 1);
			memcpy(devname + size, afs_root_cell,
			       sizeof(afs_root_cell));
			rwpath = true;
		} else {
			devname[0] = '%';
			memcpy(devname + 1, mntpt->d_name.name, size);
			memcpy(devname + size + 1, afs_root_cell,
			       sizeof(afs_root_cell));
		}
	} else {
		/* read the contents of the AFS special symlink */
		loff_t size = i_size_read(mntpt->d_inode);
		char *buf;

		ret = -EINVAL;
		if (size > PAGE_SIZE - 1)
			goto error_no_page;

		page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
		if (IS_ERR(page)) {
			ret = PTR_ERR(page);
			goto error_no_page;
		}

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

		buf = kmap_atomic(page, KM_USER0);
		memcpy(devname, buf, size);
		kunmap_atomic(buf, KM_USER0);
		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 || rwpath)
		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:
	page_cache_release(page);
error_no_page:
	free_page((unsigned long) options);
error_no_options:
	free_page((unsigned long) devname);
error_no_devname:
	_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->path.mnt->mnt_devname,
	       dentry,
	       nd->path.dentry->d_name.name);

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

	newmnt = afs_mntpt_do_automount(nd->path.dentry);
	if (IS_ERR(newmnt)) {
		path_put(&nd->path);
		return (void *)newmnt;
	}

	mntget(newmnt);
	err = do_add_mount(newmnt, &nd->path, MNT_SHRINKABLE, &afs_vfsmounts);
	switch (err) {
	case 0:
		path_put(&nd->path);
		nd->path.mnt = newmnt;
		nd->path.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->path.dentry) &&
		       follow_down(&nd->path))
			;
		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();
}
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/fs.h>
	16	#include <linux/pagemap.h>
	17	#include <linux/mount.h>
	18	#include <linux/namei.h>
5a0e3ad6	19	#include <linux/gfp.h>
1da177e4 LT	20	#include "internal.h"
	21
	22
	23	static struct dentry afs_mntpt_lookup(struct inode dir,
	24	struct dentry *dentry,
	25	struct nameidata *nd);
	26	static int afs_mntpt_open(struct inode inode, struct file file);
008b150a	27	static void afs_mntpt_follow_link(struct dentry dentry, struct nameidata *nd);
08e0e7c8	28	static void afs_mntpt_expiry_timed_out(struct work_struct *work);
1da177e4	29
4b6f5d20	30	const struct file_operations afs_mntpt_file_operations = {
1da177e4	31	.open = afs_mntpt_open,
6038f373	32	.llseek = noop_llseek,
1da177e4 LT	33	};
1da177e4 LT	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,
416351f2	39	.getattr = afs_getattr,
1da177e4 LT	40	};
1da177e4 LT	41
bec5eb61	42	const struct inode_operations afs_autocell_inode_operations = {
	43	.follow_link = afs_mntpt_follow_link,
	44	.getattr = afs_getattr,
	45	};
	46
1da177e4	47	static LIST_HEAD(afs_vfsmounts);
08e0e7c8	48	static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
1da177e4	49
c1206a2c	50	static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
1da177e4	51
1da177e4 LT	52	/*
	53	* check a symbolic link to see whether it actually encodes a mountpoint
	54	* - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
	55	*/
00d3b7a4	56	int afs_mntpt_check_symlink(struct afs_vnode vnode, struct key key)
1da177e4 LT	57	{
1da177e4 LT	58	struct page *page;
1da177e4 LT	59	size_t size;
	60	char *buf;
	61	int ret;
	62
416351f2 DH	63	_enter("{%x:%u,%u}",
416351f2 DH	64	vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
1da177e4 LT	65
1da177e4 LT	66	/* read the contents of the symlink into the pagecache */
f6d335c0 AV	67	page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
f6d335c0 AV	68	afs_page_filler, key);
1da177e4 LT	69	if (IS_ERR(page)) {
	70	ret = PTR_ERR(page);
	71	goto out;
	72	}
	73
	74	ret = -EIO;
1da177e4 LT	75	if (PageError(page))
	76	goto out_free;
	77
6fe6900e NP	78	buf = kmap(page);
6fe6900e NP	79
1da177e4 LT	80	/* examine the symlink's contents */
1da177e4 LT	81	size = vnode->status.size;
08e0e7c8	82	_debug("symlink to %.s", (int) size, (int) size, buf);
1da177e4 LT	83
	84	if (size > 2 &&
	85	(buf[0] == '%' \|\| buf[0] == '#') &&
	86	buf[size - 1] == '.'
	87	) {
	88	_debug("symlink is a mountpoint");
	89	spin_lock(&vnode->lock);
08e0e7c8	90	set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
1da177e4 LT	91	spin_unlock(&vnode->lock);
	92	}
	93
	94	ret = 0;
	95
1da177e4	96	kunmap(page);
6fe6900e	97	out_free:
1da177e4	98	page_cache_release(page);
ec26815a	99	out:
1da177e4 LT	100	_leave(" = %d", ret);
1da177e4 LT	101	return ret;
ec26815a	102	}
1da177e4	103
1da177e4 LT	104	/*
	105	* no valid lookup procedure on this sort of dir
	106	*/
	107	static struct dentry afs_mntpt_lookup(struct inode dir,
	108	struct dentry *dentry,
	109	struct nameidata *nd)
	110	{
08e0e7c8	111	_enter("%p,%p{%p{%s},%s}",
1da177e4 LT	112	dir,
	113	dentry,
	114	dentry->d_parent,
	115	dentry->d_parent ?
	116	dentry->d_parent->d_name.name : (const unsigned char *) "",
	117	dentry->d_name.name);
	118
	119	return ERR_PTR(-EREMOTE);
ec26815a	120	}
1da177e4	121
1da177e4 LT	122	/*
	123	* no valid open procedure on this sort of dir
	124	*/
	125	static int afs_mntpt_open(struct inode inode, struct file file)
	126	{
08e0e7c8	127	_enter("%p,%p{%p{%s},%s}",
1da177e4	128	inode, file,
1d56a969 JS	129	file->f_path.dentry->d_parent,
	130	file->f_path.dentry->d_parent ?
	131	file->f_path.dentry->d_parent->d_name.name :
1da177e4	132	(const unsigned char *) "",
1d56a969	133	file->f_path.dentry->d_name.name);
1da177e4 LT	134
1da177e4 LT	135	return -EREMOTE;
ec26815a	136	}
1da177e4	137
1da177e4 LT	138	/*
	139	* create a vfsmount to be automounted
	140	*/
	141	static struct vfsmount afs_mntpt_do_automount(struct dentry mntpt)
	142	{
	143	struct afs_super_info *super;
	144	struct vfsmount *mnt;
bec5eb61	145	struct afs_vnode *vnode;
083fd8b2	146	struct page *page;
bec5eb61	147	char devname, options;
bec5eb61	148	bool rwpath = false;
1da177e4 LT	149	int ret;
1da177e4 LT	150
08e0e7c8	151	_enter("{%s}", mntpt->d_name.name);
1da177e4 LT	152
	153	BUG_ON(!mntpt->d_inode);
	154
1da177e4 LT	155	ret = -ENOMEM;
	156	devname = (char *) get_zeroed_page(GFP_KERNEL);
	157	if (!devname)
083fd8b2	158	goto error_no_devname;
1da177e4 LT	159
	160	options = (char *) get_zeroed_page(GFP_KERNEL);
	161	if (!options)
083fd8b2	162	goto error_no_options;
1da177e4	163
bec5eb61	164	vnode = AFS_FS_I(mntpt->d_inode);
	165	if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
	166	/* if the directory is a pseudo directory, use the d_name */
	167	static const char afs_root_cell[] = ":root.cell.";
	168	unsigned size = mntpt->d_name.len;
	169
	170	ret = -ENOENT;
	171	if (size < 2 \|\| size > AFS_MAXCELLNAME)
	172	goto error_no_page;
	173
	174	if (mntpt->d_name.name[0] == '.') {
	175	devname[0] = '#';
	176	memcpy(devname + 1, mntpt->d_name.name, size - 1);
	177	memcpy(devname + size, afs_root_cell,
	178	sizeof(afs_root_cell));
	179	rwpath = true;
	180	} else {
	181	devname[0] = '%';
	182	memcpy(devname + 1, mntpt->d_name.name, size);
	183	memcpy(devname + size + 1, afs_root_cell,
	184	sizeof(afs_root_cell));
	185	}
	186	} else {
	187	/* read the contents of the AFS special symlink */
	188	loff_t size = i_size_read(mntpt->d_inode);
	189	char *buf;
	190
	191	ret = -EINVAL;
	192	if (size > PAGE_SIZE - 1)
	193	goto error_no_page;
	194
	195	page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
	196	if (IS_ERR(page)) {
	197	ret = PTR_ERR(page);
	198	goto error_no_page;
	199	}
	200
	201	ret = -EIO;
	202	if (PageError(page))
	203	goto error;
	204
	205	buf = kmap_atomic(page, KM_USER0);
	206	memcpy(devname, buf, size);
	207	kunmap_atomic(buf, KM_USER0);
	208	page_cache_release(page);
	209	page = NULL;
1da177e4 LT	210	}
1da177e4 LT	211
1da177e4 LT	212	/* work out what options we want */
	213	super = AFS_FS_S(mntpt->d_sb);
	214	memcpy(options, "cell=", 5);
	215	strcpy(options + 5, super->volume->cell->name);
bec5eb61	216	if (super->volume->type == AFSVL_RWVOL \|\| rwpath)
1da177e4 LT	217	strcat(options, ",rwpath");
	218
	219	/* try and do the mount */
08e0e7c8	220	_debug("--- attempting mount %s -o %s ---", devname, options);
1f5ce9e9	221	mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
08e0e7c8	222	_debug("--- mount result %p ---", mnt);
1da177e4 LT	223
	224	free_page((unsigned long) devname);
	225	free_page((unsigned long) options);
08e0e7c8	226	_leave(" = %p", mnt);
1da177e4 LT	227	return mnt;
1da177e4 LT	228
ec26815a	229	error:
083fd8b2 DH	230	page_cache_release(page);
	231	error_no_page:
	232	free_page((unsigned long) options);
	233	error_no_options:
	234	free_page((unsigned long) devname);
	235	error_no_devname:
08e0e7c8	236	_leave(" = %d", ret);
1da177e4	237	return ERR_PTR(ret);
ec26815a	238	}
1da177e4	239
1da177e4 LT	240	/*
	241	* follow a link from a mountpoint directory, thus causing it to be mounted
	242	*/
008b150a	243	static void afs_mntpt_follow_link(struct dentry dentry, struct nameidata *nd)
1da177e4 LT	244	{
1da177e4 LT	245	struct vfsmount *newmnt;
1da177e4 LT	246	int err;
1da177e4 LT	247
00d3b7a4	248	_enter("%p{%s},{%s:%p{%s},}",
1da177e4 LT	249	dentry,
1da177e4 LT	250	dentry->d_name.name,
4ac91378	251	nd->path.mnt->mnt_devname,
1da177e4	252	dentry,
4ac91378	253	nd->path.dentry->d_name.name);
1da177e4	254
4ac91378 JB	255	dput(nd->path.dentry);
4ac91378 JB	256	nd->path.dentry = dget(dentry);
08e0e7c8	257
4ac91378	258	newmnt = afs_mntpt_do_automount(nd->path.dentry);
1da177e4	259	if (IS_ERR(newmnt)) {
1d957f9b	260	path_put(&nd->path);
008b150a	261	return (void *)newmnt;
1da177e4 LT	262	}
1da177e4 LT	263
08e0e7c8	264	mntget(newmnt);
8d66bf54	265	err = do_add_mount(newmnt, &nd->path, MNT_SHRINKABLE, &afs_vfsmounts);
08e0e7c8 DH	266	switch (err) {
08e0e7c8 DH	267	case 0:
09da5916	268	path_put(&nd->path);
4ac91378 JB	269	nd->path.mnt = newmnt;
4ac91378 JB	270	nd->path.dentry = dget(newmnt->mnt_root);
08e0e7c8 DH	271	schedule_delayed_work(&afs_mntpt_expiry_timer,
	272	afs_mntpt_expiry_timeout * HZ);
	273	break;
	274	case -EBUSY:
	275	/* someone else made a mount here whilst we were busy */
4ac91378	276	while (d_mountpoint(nd->path.dentry) &&
9393bd07	277	follow_down(&nd->path))
08e0e7c8 DH	278	;
	279	err = 0;
	280	default:
	281	mntput(newmnt);
	282	break;
1da177e4 LT	283	}
1da177e4 LT	284
08e0e7c8	285	_leave(" = %d", err);
008b150a	286	return ERR_PTR(err);
ec26815a	287	}
1da177e4	288
1da177e4 LT	289	/*
	290	* handle mountpoint expiry timer going off
	291	*/
08e0e7c8	292	static void afs_mntpt_expiry_timed_out(struct work_struct *work)
1da177e4	293	{
08e0e7c8 DH	294	_enter("");
	295
	296	if (!list_empty(&afs_vfsmounts)) {
	297	mark_mounts_for_expiry(&afs_vfsmounts);
	298	schedule_delayed_work(&afs_mntpt_expiry_timer,
	299	afs_mntpt_expiry_timeout * HZ);
	300	}
	301
	302	_leave("");
	303	}
1da177e4	304
08e0e7c8 DH	305	/*
	306	* kill the AFS mountpoint timer if it's still running
	307	*/
	308	void afs_mntpt_kill_timer(void)
	309	{
	310	_enter("");
1da177e4	311
08e0e7c8 DH	312	ASSERT(list_empty(&afs_vfsmounts));
	313	cancel_delayed_work(&afs_mntpt_expiry_timer);
	314	flush_scheduled_work();
	315	}