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