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

/* mntpt.c: mountpoint management
 *
 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * 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/sched.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/namespace.h>
#include "super.h"
#include "cell.h"
#include "volume.h"
#include "vnode.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);

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

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 void afs_mntpt_expiry_timed_out(struct afs_timer *timer);

struct afs_timer_ops afs_mntpt_expiry_timer_ops = {
	.timed_out	= afs_mntpt_expiry_timed_out,
};

struct afs_timer afs_mntpt_expiry_timer;

unsigned long afs_mntpt_expiry_timeout = 20;

/*****************************************************************************/
/*
 * 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 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, NULL);
	if (IS_ERR(page)) {
		ret = PTR_ERR(page);
		goto out;
	}

	ret = -EIO;
	wait_on_page_locked(page);
	buf = kmap(page);
	if (!PageUptodate(page))
		goto out_free;
	if (PageError(page))
		goto out_free;

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

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

	ret = 0;

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

} /* end afs_mntpt_check_symlink() */

/*****************************************************************************/
/*
 * no valid lookup procedure on this sort of dir
 */
static struct dentry *afs_mntpt_lookup(struct inode *dir,
				       struct dentry *dentry,
				       struct nameidata *nd)
{
	kenter("%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);
} /* end afs_mntpt_lookup() */

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

	return -EREMOTE;
} /* end afs_mntpt_open() */

/*****************************************************************************/
/*
 * 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;

	kenter("{%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;
	wait_on_page_locked(page);
	if (!PageUptodate(page) || 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 */
	kdebug("--- attempting mount %s -o %s ---", devname, options);
	mnt = do_kern_mount("afs", 0, devname, options);
	kdebug("--- mount result %p ---", mnt);

	free_page((unsigned long) devname);
	free_page((unsigned long) options);
	kleave(" = %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);
	kleave(" = %d", ret);
	return ERR_PTR(ret);
} /* end afs_mntpt_do_automount() */

/*****************************************************************************/
/*
 * 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;
	struct dentry *old_dentry;
	int err;

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

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

	old_dentry = nd->dentry;
	nd->dentry = dentry;
	err = do_add_mount(newmnt, nd, 0, &afs_vfsmounts);
	nd->dentry = old_dentry;

	path_release(nd);

	if (!err) {
		mntget(newmnt);
		nd->mnt = newmnt;
		dget(newmnt->mnt_root);
		nd->dentry = newmnt->mnt_root;
	}

	kleave(" = %d", err);
	return ERR_PTR(err);
} /* end afs_mntpt_follow_link() */

/*****************************************************************************/
/*
 * handle mountpoint expiry timer going off
 */
static void afs_mntpt_expiry_timed_out(struct afs_timer *timer)
{
	kenter("");

	mark_mounts_for_expiry(&afs_vfsmounts);

	afs_kafstimod_add_timer(&afs_mntpt_expiry_timer,
				afs_mntpt_expiry_timeout * HZ);

	kleave("");
} /* end afs_mntpt_expiry_timed_out() */
Commit	Line	Data
1da177e4 LT	1	/* mntpt.c: mountpoint management
	2	*
	3	* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells ([email protected])
	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>
	15	#include <linux/sched.h>
	16	#include <linux/slab.h>
	17	#include <linux/fs.h>
	18	#include <linux/pagemap.h>
	19	#include <linux/mount.h>
	20	#include <linux/namei.h>
	21	#include <linux/namespace.h>
	22	#include "super.h"
	23	#include "cell.h"
	24	#include "volume.h"
	25	#include "vnode.h"
	26	#include "internal.h"
	27
	28
	29	static struct dentry afs_mntpt_lookup(struct inode dir,
	30	struct dentry *dentry,
	31	struct nameidata *nd);
	32	static int afs_mntpt_open(struct inode inode, struct file file);
008b150a	33	static void afs_mntpt_follow_link(struct dentry dentry, struct nameidata *nd);
1da177e4	34
4b6f5d20	35	const struct file_operations afs_mntpt_file_operations = {
1da177e4 LT	36	.open = afs_mntpt_open,
	37	};
	38
	39	struct inode_operations afs_mntpt_inode_operations = {
	40	.lookup = afs_mntpt_lookup,
	41	.follow_link = afs_mntpt_follow_link,
	42	.readlink = page_readlink,
	43	.getattr = afs_inode_getattr,
	44	};
	45
	46	static LIST_HEAD(afs_vfsmounts);
	47
	48	static void afs_mntpt_expiry_timed_out(struct afs_timer *timer);
	49
	50	struct afs_timer_ops afs_mntpt_expiry_timer_ops = {
	51	.timed_out = afs_mntpt_expiry_timed_out,
	52	};
	53
	54	struct afs_timer afs_mntpt_expiry_timer;
	55
	56	unsigned long afs_mntpt_expiry_timeout = 20;
	57
	58	/*****************************************************************************/
	59	/*
	60	* check a symbolic link to see whether it actually encodes a mountpoint
	61	* - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
	62	*/
	63	int afs_mntpt_check_symlink(struct afs_vnode *vnode)
	64	{
	65	struct page *page;
1da177e4 LT	66	size_t size;
	67	char *buf;
	68	int ret;
	69
	70	_enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique);
	71
	72	/* read the contents of the symlink into the pagecache */
090d2b18	73	page = read_mapping_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, NULL);
1da177e4 LT	74	if (IS_ERR(page)) {
	75	ret = PTR_ERR(page);
	76	goto out;
	77	}
	78
	79	ret = -EIO;
	80	wait_on_page_locked(page);
	81	buf = kmap(page);
	82	if (!PageUptodate(page))
	83	goto out_free;
	84	if (PageError(page))
	85	goto out_free;
	86
	87	/* examine the symlink's contents */
	88	size = vnode->status.size;
	89	_debug("symlink to %.s", size, (int) size, buf);
	90
	91	if (size > 2 &&
	92	(buf[0] == '%' \|\| buf[0] == '#') &&
	93	buf[size - 1] == '.'
	94	) {
	95	_debug("symlink is a mountpoint");
	96	spin_lock(&vnode->lock);
	97	vnode->flags \|= AFS_VNODE_MOUNTPOINT;
	98	spin_unlock(&vnode->lock);
	99	}
	100
	101	ret = 0;
	102
	103	out_free:
	104	kunmap(page);
	105	page_cache_release(page);
	106	out:
	107	_leave(" = %d", ret);
	108	return ret;
	109
	110	} /* end afs_mntpt_check_symlink() */
	111
	112	/*****************************************************************************/
	113	/*
	114	* no valid lookup procedure on this sort of dir
	115	*/
	116	static struct dentry afs_mntpt_lookup(struct inode dir,
	117	struct dentry *dentry,
	118	struct nameidata *nd)
	119	{
	120	kenter("%p,%p{%p{%s},%s}",
	121	dir,
	122	dentry,
	123	dentry->d_parent,
	124	dentry->d_parent ?
	125	dentry->d_parent->d_name.name : (const unsigned char *) "",
	126	dentry->d_name.name);
	127
	128	return ERR_PTR(-EREMOTE);
	129	} /* end afs_mntpt_lookup() */
	130
	131	/*****************************************************************************/
	132	/*
	133	* no valid open procedure on this sort of dir
	134	*/
	135	static int afs_mntpt_open(struct inode inode, struct file file)
	136	{
	137	kenter("%p,%p{%p{%s},%s}",
138	inode, file,
139	file->f_dentry->d_parent,
140	file->f_dentry->d_parent ?
141	file->f_dentry->d_parent->d_name.name :
142	(const unsigned char *) "",
143	file->f_dentry->d_name.name);
144
145	return -EREMOTE;
146	} /* end afs_mntpt_open() */
147
148	/*****************************************************************************/
149	/*
150	* create a vfsmount to be automounted
151	*/
152	static struct vfsmount afs_mntpt_do_automount(struct dentry mntpt)
153	{
154	struct afs_super_info *super;
155	struct vfsmount *mnt;
156	struct page *page = NULL;
157	size_t size;
158	char buf, devname = NULL, *options = NULL;
1da177e4 LT	159	int ret;
	160
	161	kenter("{%s}", mntpt->d_name.name);
	162
	163	BUG_ON(!mntpt->d_inode);
	164
	165	ret = -EINVAL;
	166	size = mntpt->d_inode->i_size;
	167	if (size > PAGE_SIZE - 1)
	168	goto error;
	169
	170	ret = -ENOMEM;
	171	devname = (char *) get_zeroed_page(GFP_KERNEL);
	172	if (!devname)
	173	goto error;
	174
	175	options = (char *) get_zeroed_page(GFP_KERNEL);
	176	if (!options)
	177	goto error;
	178
	179	/* read the contents of the AFS special symlink */
090d2b18	180	page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
1da177e4 LT	181	if (IS_ERR(page)) {
	182	ret = PTR_ERR(page);
	183	goto error;
	184	}
	185
	186	ret = -EIO;
	187	wait_on_page_locked(page);
	188	if (!PageUptodate(page) \|\| PageError(page))
	189	goto error;
	190
	191	buf = kmap(page);
	192	memcpy(devname, buf, size);
	193	kunmap(page);
	194	page_cache_release(page);
	195	page = NULL;
	196
	197	/* work out what options we want */
	198	super = AFS_FS_S(mntpt->d_sb);
	199	memcpy(options, "cell=", 5);
	200	strcpy(options + 5, super->volume->cell->name);
	201	if (super->volume->type == AFSVL_RWVOL)
	202	strcat(options, ",rwpath");
	203
	204	/* try and do the mount */
	205	kdebug("--- attempting mount %s -o %s ---", devname, options);
	206	mnt = do_kern_mount("afs", 0, devname, options);
	207	kdebug("--- mount result %p ---", mnt);
	208
	209	free_page((unsigned long) devname);
	210	free_page((unsigned long) options);
	211	kleave(" = %p", mnt);
	212	return mnt;
	213
	214	error:
	215	if (page)
	216	page_cache_release(page);
	217	if (devname)
	218	free_page((unsigned long) devname);
	219	if (options)
	220	free_page((unsigned long) options);
	221	kleave(" = %d", ret);
	222	return ERR_PTR(ret);
	223	} /* end afs_mntpt_do_automount() */
	224
	225	/*****************************************************************************/
	226	/*
	227	* follow a link from a mountpoint directory, thus causing it to be mounted
	228	*/
008b150a	229	static void afs_mntpt_follow_link(struct dentry dentry, struct nameidata *nd)
1da177e4 LT	230	{
	231	struct vfsmount *newmnt;
	232	struct dentry *old_dentry;
	233	int err;
	234
	235	kenter("%p{%s},{%s:%p{%s}}",
	236	dentry,
	237	dentry->d_name.name,
	238	nd->mnt->mnt_devname,
	239	dentry,
	240	nd->dentry->d_name.name);
	241
	242	newmnt = afs_mntpt_do_automount(dentry);
	243	if (IS_ERR(newmnt)) {
	244	path_release(nd);
008b150a	245	return (void *)newmnt;
1da177e4 LT	246	}
	247
	248	old_dentry = nd->dentry;
	249	nd->dentry = dentry;
	250	err = do_add_mount(newmnt, nd, 0, &afs_vfsmounts);
	251	nd->dentry = old_dentry;
	252
	253	path_release(nd);
	254
	255	if (!err) {
	256	mntget(newmnt);
	257	nd->mnt = newmnt;
	258	dget(newmnt->mnt_root);
	259	nd->dentry = newmnt->mnt_root;
	260	}
	261
	262	kleave(" = %d", err);
008b150a	263	return ERR_PTR(err);
1da177e4 LT	264	} /* end afs_mntpt_follow_link() */
	265
	266	/*****************************************************************************/
	267	/*
	268	* handle mountpoint expiry timer going off
	269	*/
	270	static void afs_mntpt_expiry_timed_out(struct afs_timer *timer)
	271	{
	272	kenter("");
	273
	274	mark_mounts_for_expiry(&afs_vfsmounts);
	275
	276	afs_kafstimod_add_timer(&afs_mntpt_expiry_timer,
	277	afs_mntpt_expiry_timeout * HZ);
	278
	279	kleave("");
	280	} /* end afs_mntpt_expiry_timed_out() */