[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / afs / mntpt.c

/* 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/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;
	filler_t *filler;
	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 */
	filler = (filler_t *) AFS_VNODE_TO_I(vnode)->i_mapping->a_ops->readpage;

	page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
			       filler, 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;
	filler_t *filler;
	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 */
	filler = (filler_t *)mntpt->d_inode->i_mapping->a_ops->readpage;

	page = read_cache_page(mntpt->d_inode->i_mapping, 0, filler, 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 (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>
	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;
	66	filler_t *filler;
	67	size_t size;
	68	char *buf;
	69	int ret;
	70
	71	_enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique);
	72
	73	/* read the contents of the symlink into the pagecache */
	74	filler = (filler_t *) AFS_VNODE_TO_I(vnode)->i_mapping->a_ops->readpage;
	75
	76	page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
	77	filler, NULL);
	78	if (IS_ERR(page)) {
	79	ret = PTR_ERR(page);
	80	goto out;
	81	}
	82
	83	ret = -EIO;
	84	wait_on_page_locked(page);
	85	buf = kmap(page);
	86	if (!PageUptodate(page))
	87	goto out_free;
	88	if (PageError(page))
	89	goto out_free;
	90
	91	/* examine the symlink's contents */
	92	size = vnode->status.size;
	93	_debug("symlink to %.s", size, (int) size, buf);
	94
	95	if (size > 2 &&
	96	(buf[0] == '%' \|\| buf[0] == '#') &&
	97	buf[size - 1] == '.'
	98	) {
	99	_debug("symlink is a mountpoint");
100	spin_lock(&vnode->lock);
101	vnode->flags \|= AFS_VNODE_MOUNTPOINT;
102	spin_unlock(&vnode->lock);
103	}
104
105	ret = 0;
106
107	out_free:
108	kunmap(page);
109	page_cache_release(page);
110	out:
111	_leave(" = %d", ret);
112	return ret;
113
114	} /* end afs_mntpt_check_symlink() */
115
116	/*****************************************************************************/
117	/*
118	* no valid lookup procedure on this sort of dir
119	*/
120	static struct dentry afs_mntpt_lookup(struct inode dir,
121	struct dentry *dentry,
122	struct nameidata *nd)
123	{
124	kenter("%p,%p{%p{%s},%s}",
125	dir,
126	dentry,
127	dentry->d_parent,
128	dentry->d_parent ?
129	dentry->d_parent->d_name.name : (const unsigned char *) "",
130	dentry->d_name.name);
131
132	return ERR_PTR(-EREMOTE);
133	} /* end afs_mntpt_lookup() */
134
135	/*****************************************************************************/
136	/*
137	* no valid open procedure on this sort of dir
138	*/
139	static int afs_mntpt_open(struct inode inode, struct file file)
140	{
141	kenter("%p,%p{%p{%s},%s}",
142	inode, file,
143	file->f_dentry->d_parent,
144	file->f_dentry->d_parent ?
145	file->f_dentry->d_parent->d_name.name :
146	(const unsigned char *) "",
147	file->f_dentry->d_name.name);
148
149	return -EREMOTE;
150	} /* end afs_mntpt_open() */
151
152	/*****************************************************************************/
153	/*
154	* create a vfsmount to be automounted
155	*/
156	static struct vfsmount afs_mntpt_do_automount(struct dentry mntpt)
157	{
158	struct afs_super_info *super;
159	struct vfsmount *mnt;
160	struct page *page = NULL;
161	size_t size;
162	char buf, devname = NULL, *options = NULL;
163	filler_t *filler;
164	int ret;
165
166	kenter("{%s}", mntpt->d_name.name);
167
168	BUG_ON(!mntpt->d_inode);
169
170	ret = -EINVAL;
171	size = mntpt->d_inode->i_size;
172	if (size > PAGE_SIZE - 1)
173	goto error;
174
175	ret = -ENOMEM;
176	devname = (char *) get_zeroed_page(GFP_KERNEL);
177	if (!devname)
178	goto error;
179
180	options = (char *) get_zeroed_page(GFP_KERNEL);
181	if (!options)
182	goto error;
183
184	/* read the contents of the AFS special symlink */
185	filler = (filler_t *)mntpt->d_inode->i_mapping->a_ops->readpage;
186
187	page = read_cache_page(mntpt->d_inode->i_mapping, 0, filler, NULL);
188	if (IS_ERR(page)) {
189	ret = PTR_ERR(page);
190	goto error;
191	}
192
193	ret = -EIO;
194	wait_on_page_locked(page);
195	if (!PageUptodate(page) \|\| PageError(page))
196	goto error;
197
198	buf = kmap(page);
199	memcpy(devname, buf, size);
200	kunmap(page);
201	page_cache_release(page);
202	page = NULL;
203
204	/* work out what options we want */
205	super = AFS_FS_S(mntpt->d_sb);
206	memcpy(options, "cell=", 5);
207	strcpy(options + 5, super->volume->cell->name);
208	if (super->volume->type == AFSVL_RWVOL)
209	strcat(options, ",rwpath");
210
211	/* try and do the mount */
212	kdebug("--- attempting mount %s -o %s ---", devname, options);
213	mnt = do_kern_mount("afs", 0, devname, options);
214	kdebug("--- mount result %p ---", mnt);
215
216	free_page((unsigned long) devname);
217	free_page((unsigned long) options);
218	kleave(" = %p", mnt);
219	return mnt;
220
221	error:
222	if (page)
223	page_cache_release(page);
224	if (devname)
225	free_page((unsigned long) devname);
226	if (options)
227	free_page((unsigned long) options);
228	kleave(" = %d", ret);
229	return ERR_PTR(ret);
230	} /* end afs_mntpt_do_automount() */
231
232	/*****************************************************************************/
233	/*
234	* follow a link from a mountpoint directory, thus causing it to be mounted
235	*/
008b150a	236	static void afs_mntpt_follow_link(struct dentry dentry, struct nameidata *nd)
1da177e4 LT	237	{
	238	struct vfsmount *newmnt;
	239	struct dentry *old_dentry;
	240	int err;
	241
	242	kenter("%p{%s},{%s:%p{%s}}",
	243	dentry,
	244	dentry->d_name.name,
	245	nd->mnt->mnt_devname,
	246	dentry,
	247	nd->dentry->d_name.name);
	248
	249	newmnt = afs_mntpt_do_automount(dentry);
	250	if (IS_ERR(newmnt)) {
	251	path_release(nd);
008b150a	252	return (void *)newmnt;
1da177e4 LT	253	}
	254
	255	old_dentry = nd->dentry;
	256	nd->dentry = dentry;
	257	err = do_add_mount(newmnt, nd, 0, &afs_vfsmounts);
	258	nd->dentry = old_dentry;
	259
	260	path_release(nd);
	261
	262	if (!err) {
	263	mntget(newmnt);
	264	nd->mnt = newmnt;
	265	dget(newmnt->mnt_root);
	266	nd->dentry = newmnt->mnt_root;
	267	}
	268
	269	kleave(" = %d", err);
008b150a	270	return ERR_PTR(err);
1da177e4 LT	271	} /* end afs_mntpt_follow_link() */
	272
	273	/*****************************************************************************/
	274	/*
	275	* handle mountpoint expiry timer going off
	276	*/
	277	static void afs_mntpt_expiry_timed_out(struct afs_timer *timer)
	278	{
	279	kenter("");
	280
	281	mark_mounts_for_expiry(&afs_vfsmounts);
	282
	283	afs_kafstimod_add_timer(&afs_mntpt_expiry_timer,
	284	afs_mntpt_expiry_timeout * HZ);
	285
	286	kleave("");
	287	} /* end afs_mntpt_expiry_timed_out() */