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DEFINITIONS
This source file includes following definitions.
- afs_mntpt_check_symlink
- afs_mntpt_lookup
- afs_mntpt_open
- afs_mntpt_do_automount
- afs_mntpt_follow_link
- afs_mntpt_expiry_timed_out
- afs_mntpt_kill_timer
/* 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 "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,
};
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 file file = {
.private_data = 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_mapping_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, &file);
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 page *page = NULL;
size_t size;
char *buf, *devname = NULL, *options = NULL;
int ret;
_enter("{%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;
if (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 */
_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:
if (page)
page_cache_release(page);
if (devname)
free_page((unsigned long) devname);
if (options)
free_page((unsigned long) options);
_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.mnt, &nd->path.dentry))
;
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();
}