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/* 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/nfs4_mount.h>
#include <linux/lockd/bind.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/nfs_idmap.h>
#include <linux/vfs.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include "nfs4_fs.h"
#include "delegation.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_alloc_root(inode);
if (sb->s_root == NULL) {
iput(inode);
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);
list_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)
{
struct nfs_server *server = NFS_SB(sb);
struct nfs_fsinfo fsinfo;
struct dentry *ret;
struct inode *inode;
int error;
/* get the actual root for this mount */
fsinfo.fattr = nfs_alloc_fattr();
if (fsinfo.fattr == NULL)
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);
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_alias(inode);
if (IS_ERR(ret)) {
dprintk("nfs_get_root: get root dentry failed\n");
goto out;
}
security_d_instantiate(ret, inode);
out:
nfs_free_fattr(fsinfo.fattr);
return ret;
}
#ifdef CONFIG_NFS_V4
int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh)
{
struct nfs_fsinfo fsinfo;
int ret = -ENOMEM;
dprintk("--> nfs4_get_rootfh()\n");
fsinfo.fattr = nfs_alloc_fattr();
if (fsinfo.fattr == NULL)
goto out;
/* Start by getting the root filehandle from the server */
ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
if (ret < 0) {
dprintk("nfs4_get_rootfh: getroot error = %d\n", -ret);
goto out;
}
if (!(fsinfo.fattr->valid & NFS_ATTR_FATTR_TYPE)
|| !S_ISDIR(fsinfo.fattr->mode)) {
printk(KERN_ERR "nfs4_get_rootfh:"
" getroot encountered non-directory\n");
ret = -ENOTDIR;
goto out;
}
if (fsinfo.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
printk(KERN_ERR "nfs4_get_rootfh:"
" getroot obtained referral\n");
ret = -EREMOTE;
goto out;
}
memcpy(&server->fsid, &fsinfo.fattr->fsid, sizeof(server->fsid));
out:
nfs_free_fattr(fsinfo.fattr);
dprintk("<-- nfs4_get_rootfh() = %d\n", ret);
return ret;
}
/*
* get an NFS4 root dentry from the root filehandle
*/
struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
{
struct nfs_server *server = NFS_SB(sb);
struct nfs_fattr *fattr = NULL;
struct dentry *ret;
struct inode *inode;
int error;
dprintk("--> nfs4_get_root()\n");
/* get the info about the server and filesystem */
error = nfs4_server_capabilities(server, mntfh);
if (error < 0) {
dprintk("nfs_get_root: getcaps error = %d\n",
-error);
return ERR_PTR(error);
}
fattr = nfs_alloc_fattr();
if (fattr == NULL)
return ERR_PTR(-ENOMEM);;
/* get the actual root for this mount */
error = server->nfs_client->rpc_ops->getattr(server, mntfh, fattr);
if (error < 0) {
dprintk("nfs_get_root: getattr error = %d\n", -error);
ret = ERR_PTR(error);
goto out;
}
if (fattr->valid & NFS_ATTR_FATTR_FSID &&
!nfs_fsid_equal(&server->fsid, &fattr->fsid))
memcpy(&server->fsid, &fattr->fsid, sizeof(server->fsid));
inode = nfs_fhget(sb, mntfh, fattr);
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_alias(inode);
if (IS_ERR(ret)) {
dprintk("nfs_get_root: get root dentry failed\n");
goto out;
}
security_d_instantiate(ret, inode);
out:
nfs_free_fattr(fattr);
dprintk("<-- nfs4_get_root()\n");
return ret;
}
#endif /* CONFIG_NFS_V4 */
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