[people/ms/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/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,
};

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 LT	31	.open = afs_mntpt_open,
	32	};
	33
754661f1	34	const struct inode_operations afs_mntpt_inode_operations = {
1da177e4 LT	35	.lookup = afs_mntpt_lookup,
	36	.follow_link = afs_mntpt_follow_link,
	37	.readlink = page_readlink,
416351f2	38	.getattr = afs_getattr,
1da177e4 LT	39	};
1da177e4 LT	40
bec5eb61	41	const struct inode_operations afs_autocell_inode_operations = {
	42	.follow_link = afs_mntpt_follow_link,
	43	.getattr = afs_getattr,
	44	};
	45
1da177e4	46	static LIST_HEAD(afs_vfsmounts);
08e0e7c8	47	static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
1da177e4	48
c1206a2c	49	static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
1da177e4	50
1da177e4 LT	51	/*
	52	* check a symbolic link to see whether it actually encodes a mountpoint
	53	* - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
	54	*/
00d3b7a4	55	int afs_mntpt_check_symlink(struct afs_vnode vnode, struct key key)
1da177e4 LT	56	{
1da177e4 LT	57	struct page *page;
1da177e4 LT	58	size_t size;
	59	char *buf;
	60	int ret;
	61
416351f2 DH	62	_enter("{%x:%u,%u}",
416351f2 DH	63	vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
1da177e4 LT	64
1da177e4 LT	65	/* read the contents of the symlink into the pagecache */
f6d335c0 AV	66	page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
f6d335c0 AV	67	afs_page_filler, key);
1da177e4 LT	68	if (IS_ERR(page)) {
	69	ret = PTR_ERR(page);
	70	goto out;
	71	}
	72
	73	ret = -EIO;
1da177e4 LT	74	if (PageError(page))
	75	goto out_free;
	76
6fe6900e NP	77	buf = kmap(page);
6fe6900e NP	78
1da177e4 LT	79	/* examine the symlink's contents */
1da177e4 LT	80	size = vnode->status.size;
08e0e7c8	81	_debug("symlink to %.s", (int) size, (int) size, buf);
1da177e4 LT	82
	83	if (size > 2 &&
	84	(buf[0] == '%' \|\| buf[0] == '#') &&
	85	buf[size - 1] == '.'
	86	) {
	87	_debug("symlink is a mountpoint");
	88	spin_lock(&vnode->lock);
08e0e7c8	89	set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
1da177e4 LT	90	spin_unlock(&vnode->lock);
	91	}
	92
	93	ret = 0;
	94
1da177e4	95	kunmap(page);
6fe6900e	96	out_free:
1da177e4	97	page_cache_release(page);
ec26815a	98	out:
1da177e4 LT	99	_leave(" = %d", ret);
1da177e4 LT	100	return ret;
ec26815a	101	}
1da177e4	102
1da177e4 LT	103	/*
	104	* no valid lookup procedure on this sort of dir
	105	*/
	106	static struct dentry afs_mntpt_lookup(struct inode dir,
	107	struct dentry *dentry,
	108	struct nameidata *nd)
	109	{
08e0e7c8	110	_enter("%p,%p{%p{%s},%s}",
1da177e4 LT	111	dir,
	112	dentry,
	113	dentry->d_parent,
	114	dentry->d_parent ?
	115	dentry->d_parent->d_name.name : (const unsigned char *) "",
	116	dentry->d_name.name);
	117
	118	return ERR_PTR(-EREMOTE);
ec26815a	119	}
1da177e4	120
1da177e4 LT	121	/*
	122	* no valid open procedure on this sort of dir
	123	*/
	124	static int afs_mntpt_open(struct inode inode, struct file file)
	125	{
08e0e7c8	126	_enter("%p,%p{%p{%s},%s}",
1da177e4	127	inode, file,
1d56a969 JS	128	file->f_path.dentry->d_parent,
	129	file->f_path.dentry->d_parent ?
	130	file->f_path.dentry->d_parent->d_name.name :
1da177e4	131	(const unsigned char *) "",
1d56a969	132	file->f_path.dentry->d_name.name);
1da177e4 LT	133
1da177e4 LT	134	return -EREMOTE;
ec26815a	135	}
1da177e4	136
1da177e4 LT	137	/*
	138	* create a vfsmount to be automounted
	139	*/
	140	static struct vfsmount afs_mntpt_do_automount(struct dentry mntpt)
	141	{
	142	struct afs_super_info *super;
	143	struct vfsmount *mnt;
bec5eb61	144	struct afs_vnode *vnode;
083fd8b2	145	struct page *page;
bec5eb61	146	char devname, options;
bec5eb61	147	bool rwpath = false;
1da177e4 LT	148	int ret;
1da177e4 LT	149
08e0e7c8	150	_enter("{%s}", mntpt->d_name.name);
1da177e4 LT	151
	152	BUG_ON(!mntpt->d_inode);
	153
1da177e4 LT	154	ret = -ENOMEM;
	155	devname = (char *) get_zeroed_page(GFP_KERNEL);
	156	if (!devname)
083fd8b2	157	goto error_no_devname;
1da177e4 LT	158
	159	options = (char *) get_zeroed_page(GFP_KERNEL);
	160	if (!options)
083fd8b2	161	goto error_no_options;
1da177e4	162
bec5eb61	163	vnode = AFS_FS_I(mntpt->d_inode);
	164	if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
	165	/* if the directory is a pseudo directory, use the d_name */
	166	static const char afs_root_cell[] = ":root.cell.";
	167	unsigned size = mntpt->d_name.len;
	168
	169	ret = -ENOENT;
	170	if (size < 2 \|\| size > AFS_MAXCELLNAME)
	171	goto error_no_page;
	172
	173	if (mntpt->d_name.name[0] == '.') {
	174	devname[0] = '#';
	175	memcpy(devname + 1, mntpt->d_name.name, size - 1);
	176	memcpy(devname + size, afs_root_cell,
	177	sizeof(afs_root_cell));
	178	rwpath = true;
	179	} else {
	180	devname[0] = '%';
	181	memcpy(devname + 1, mntpt->d_name.name, size);
	182	memcpy(devname + size + 1, afs_root_cell,
	183	sizeof(afs_root_cell));
	184	}
	185	} else {
	186	/* read the contents of the AFS special symlink */
	187	loff_t size = i_size_read(mntpt->d_inode);
	188	char *buf;
	189
	190	ret = -EINVAL;
	191	if (size > PAGE_SIZE - 1)
	192	goto error_no_page;
	193
	194	page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
	195	if (IS_ERR(page)) {
	196	ret = PTR_ERR(page);
	197	goto error_no_page;
	198	}
	199
	200	ret = -EIO;
	201	if (PageError(page))
	202	goto error;
	203
	204	buf = kmap_atomic(page, KM_USER0);
	205	memcpy(devname, buf, size);
	206	kunmap_atomic(buf, KM_USER0);
	207	page_cache_release(page);
	208	page = NULL;
1da177e4 LT	209	}
1da177e4 LT	210
1da177e4 LT	211	/* work out what options we want */
	212	super = AFS_FS_S(mntpt->d_sb);
	213	memcpy(options, "cell=", 5);
	214	strcpy(options + 5, super->volume->cell->name);
bec5eb61	215	if (super->volume->type == AFSVL_RWVOL \|\| rwpath)
1da177e4 LT	216	strcat(options, ",rwpath");
	217
	218	/* try and do the mount */
08e0e7c8	219	_debug("--- attempting mount %s -o %s ---", devname, options);
1f5ce9e9	220	mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
08e0e7c8	221	_debug("--- mount result %p ---", mnt);
1da177e4 LT	222
	223	free_page((unsigned long) devname);
	224	free_page((unsigned long) options);
08e0e7c8	225	_leave(" = %p", mnt);
1da177e4 LT	226	return mnt;
1da177e4 LT	227
ec26815a	228	error:
083fd8b2 DH	229	page_cache_release(page);
	230	error_no_page:
	231	free_page((unsigned long) options);
	232	error_no_options:
	233	free_page((unsigned long) devname);
	234	error_no_devname:
08e0e7c8	235	_leave(" = %d", ret);
1da177e4	236	return ERR_PTR(ret);
ec26815a	237	}
1da177e4	238
1da177e4 LT	239	/*
	240	* follow a link from a mountpoint directory, thus causing it to be mounted
	241	*/
008b150a	242	static void afs_mntpt_follow_link(struct dentry dentry, struct nameidata *nd)
1da177e4 LT	243	{
1da177e4 LT	244	struct vfsmount *newmnt;
1da177e4 LT	245	int err;
1da177e4 LT	246
00d3b7a4	247	_enter("%p{%s},{%s:%p{%s},}",
1da177e4 LT	248	dentry,
1da177e4 LT	249	dentry->d_name.name,
4ac91378	250	nd->path.mnt->mnt_devname,
1da177e4	251	dentry,
4ac91378	252	nd->path.dentry->d_name.name);
1da177e4	253
4ac91378 JB	254	dput(nd->path.dentry);
4ac91378 JB	255	nd->path.dentry = dget(dentry);
08e0e7c8	256
4ac91378	257	newmnt = afs_mntpt_do_automount(nd->path.dentry);
1da177e4	258	if (IS_ERR(newmnt)) {
1d957f9b	259	path_put(&nd->path);
008b150a	260	return (void *)newmnt;
1da177e4 LT	261	}
1da177e4 LT	262
08e0e7c8	263	mntget(newmnt);
8d66bf54	264	err = do_add_mount(newmnt, &nd->path, MNT_SHRINKABLE, &afs_vfsmounts);
08e0e7c8 DH	265	switch (err) {
08e0e7c8 DH	266	case 0:
09da5916	267	path_put(&nd->path);
4ac91378 JB	268	nd->path.mnt = newmnt;
4ac91378 JB	269	nd->path.dentry = dget(newmnt->mnt_root);
08e0e7c8 DH	270	schedule_delayed_work(&afs_mntpt_expiry_timer,
	271	afs_mntpt_expiry_timeout * HZ);
	272	break;
	273	case -EBUSY:
	274	/* someone else made a mount here whilst we were busy */
4ac91378	275	while (d_mountpoint(nd->path.dentry) &&
9393bd07	276	follow_down(&nd->path))
08e0e7c8 DH	277	;
	278	err = 0;
	279	default:
	280	mntput(newmnt);
	281	break;
1da177e4 LT	282	}
1da177e4 LT	283
08e0e7c8	284	_leave(" = %d", err);
008b150a	285	return ERR_PTR(err);
ec26815a	286	}
1da177e4	287
1da177e4 LT	288	/*
	289	* handle mountpoint expiry timer going off
	290	*/
08e0e7c8	291	static void afs_mntpt_expiry_timed_out(struct work_struct *work)
1da177e4	292	{
08e0e7c8 DH	293	_enter("");
	294
	295	if (!list_empty(&afs_vfsmounts)) {
	296	mark_mounts_for_expiry(&afs_vfsmounts);
	297	schedule_delayed_work(&afs_mntpt_expiry_timer,
	298	afs_mntpt_expiry_timeout * HZ);
	299	}
	300
	301	_leave("");
	302	}
1da177e4	303
08e0e7c8 DH	304	/*
	305	* kill the AFS mountpoint timer if it's still running
	306	*/
	307	void afs_mntpt_kill_timer(void)
	308	{
	309	_enter("");
1da177e4	310
08e0e7c8 DH	311	ASSERT(list_empty(&afs_vfsmounts));
	312	cancel_delayed_work(&afs_mntpt_expiry_timer);
	313	flush_scheduled_work();
	314	}