135 строки
3.5 KiB
C
135 строки
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* 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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#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 <linux/uaccess.h>
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#include "internal.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_splice_alias 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(&d_inode(sb->s_root)->i_lock);
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spin_lock(&sb->s_root->d_lock);
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hlist_del_init(&sb->s_root->d_u.d_alias);
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spin_unlock(&sb->s_root->d_lock);
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spin_unlock(&d_inode(sb->s_root)->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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int nfs_get_root(struct super_block *s, struct fs_context *fc)
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{
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struct nfs_fs_context *ctx = nfs_fc2context(fc);
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struct nfs_server *server = NFS_SB(s);
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struct nfs_fsinfo fsinfo;
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struct dentry *root;
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struct inode *inode;
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char *name;
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int error = -ENOMEM;
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name = kstrdup(fc->source, GFP_KERNEL);
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if (!name)
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goto out;
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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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goto out_name;
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error = server->nfs_client->rpc_ops->getroot(server, ctx->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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nfs_errorf(fc, "NFS: Couldn't getattr on root");
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goto out_fattr;
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}
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inode = nfs_fhget(s, ctx->mntfh, fsinfo.fattr, NULL);
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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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error = PTR_ERR(inode);
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nfs_errorf(fc, "NFS: Couldn't get root inode");
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goto out_fattr;
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}
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error = nfs_superblock_set_dummy_root(s, inode);
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if (error != 0)
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goto out_fattr;
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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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root = d_obtain_root(inode);
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if (IS_ERR(root)) {
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dprintk("nfs_get_root: get root dentry failed\n");
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error = PTR_ERR(root);
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nfs_errorf(fc, "NFS: Couldn't get root dentry");
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goto out_fattr;
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}
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security_d_instantiate(root, inode);
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spin_lock(&root->d_lock);
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if (IS_ROOT(root) && !root->d_fsdata &&
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!(root->d_flags & DCACHE_NFSFS_RENAMED)) {
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root->d_fsdata = name;
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name = NULL;
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}
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spin_unlock(&root->d_lock);
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fc->root = root;
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error = 0;
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out_fattr:
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nfs_free_fattr(fsinfo.fattr);
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out_name:
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kfree(name);
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out:
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return error;
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}
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