/* 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 "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,
};
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 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_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;
} /* 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 = vfs_kern_mount(&afs_fs_type, 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() */
