linux/fs/afs/mntpt.c
Arjan van de Ven 4b6f5d20b0 [PATCH] Make most file operations structs in fs/ const
This is a conversion to make the various file_operations structs in fs/
const.  Basically a regexp job, with a few manual fixups

The goal is both to increase correctness (harder to accidentally write to
shared datastructures) and reducing the false sharing of cachelines with
things that get dirty in .data (while .rodata is nicely read only and thus
cache clean)

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-28 09:16:06 -08:00

287 lines
7 KiB
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() */