134 lines
3.5 KiB
C
134 lines
3.5 KiB
C
/* getroot.c: get the root dentry for an NFS mount
|
|
*
|
|
* Copyright (C) 2006 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/module.h>
|
|
#include <linux/init.h>
|
|
|
|
#include <linux/time.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/string.h>
|
|
#include <linux/stat.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/unistd.h>
|
|
#include <linux/sunrpc/clnt.h>
|
|
#include <linux/sunrpc/stats.h>
|
|
#include <linux/nfs_fs.h>
|
|
#include <linux/nfs_mount.h>
|
|
#include <linux/lockd/bind.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/vfs.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/security.h>
|
|
|
|
#include <asm/uaccess.h>
|
|
|
|
#include "internal.h"
|
|
|
|
#define NFSDBG_FACILITY NFSDBG_CLIENT
|
|
|
|
/*
|
|
* Set the superblock root dentry.
|
|
* Note that this function frees the inode in case of error.
|
|
*/
|
|
static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode)
|
|
{
|
|
/* The mntroot acts as the dummy root dentry for this superblock */
|
|
if (sb->s_root == NULL) {
|
|
sb->s_root = d_make_root(inode);
|
|
if (sb->s_root == NULL)
|
|
return -ENOMEM;
|
|
ihold(inode);
|
|
/*
|
|
* Ensure that this dentry is invisible to d_find_alias().
|
|
* Otherwise, it may be spliced into the tree by
|
|
* d_materialise_unique if a parent directory from the same
|
|
* filesystem gets mounted at a later time.
|
|
* This again causes shrink_dcache_for_umount_subtree() to
|
|
* Oops, since the test for IS_ROOT() will fail.
|
|
*/
|
|
spin_lock(&sb->s_root->d_inode->i_lock);
|
|
spin_lock(&sb->s_root->d_lock);
|
|
hlist_del_init(&sb->s_root->d_alias);
|
|
spin_unlock(&sb->s_root->d_lock);
|
|
spin_unlock(&sb->s_root->d_inode->i_lock);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* get an NFS2/NFS3 root dentry from the root filehandle
|
|
*/
|
|
struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh,
|
|
const char *devname)
|
|
{
|
|
struct nfs_server *server = NFS_SB(sb);
|
|
struct nfs_fsinfo fsinfo;
|
|
struct dentry *ret;
|
|
struct inode *inode;
|
|
void *name = kstrdup(devname, GFP_KERNEL);
|
|
int error;
|
|
|
|
if (!name)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
/* get the actual root for this mount */
|
|
fsinfo.fattr = nfs_alloc_fattr();
|
|
if (fsinfo.fattr == NULL) {
|
|
kfree(name);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
|
|
if (error < 0) {
|
|
dprintk("nfs_get_root: getattr error = %d\n", -error);
|
|
ret = ERR_PTR(error);
|
|
goto out;
|
|
}
|
|
|
|
inode = nfs_fhget(sb, mntfh, fsinfo.fattr, NULL);
|
|
if (IS_ERR(inode)) {
|
|
dprintk("nfs_get_root: get root inode failed\n");
|
|
ret = ERR_CAST(inode);
|
|
goto out;
|
|
}
|
|
|
|
error = nfs_superblock_set_dummy_root(sb, inode);
|
|
if (error != 0) {
|
|
ret = ERR_PTR(error);
|
|
goto out;
|
|
}
|
|
|
|
/* root dentries normally start off anonymous and get spliced in later
|
|
* if the dentry tree reaches them; however if the dentry already
|
|
* exists, we'll pick it up at this point and use it as the root
|
|
*/
|
|
ret = d_obtain_root(inode);
|
|
if (IS_ERR(ret)) {
|
|
dprintk("nfs_get_root: get root dentry failed\n");
|
|
goto out;
|
|
}
|
|
|
|
security_d_instantiate(ret, inode);
|
|
spin_lock(&ret->d_lock);
|
|
if (IS_ROOT(ret) && !ret->d_fsdata &&
|
|
!(ret->d_flags & DCACHE_NFSFS_RENAMED)) {
|
|
ret->d_fsdata = name;
|
|
name = NULL;
|
|
}
|
|
spin_unlock(&ret->d_lock);
|
|
out:
|
|
kfree(name);
|
|
nfs_free_fattr(fsinfo.fattr);
|
|
return ret;
|
|
}
|