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David Howells54ceac42006-08-22 20:06:13 -04001/* getroot.c: get the root dentry for an NFS mount
2 *
3 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
David Howells54ceac42006-08-22 20:06:13 -040012#include <linux/module.h>
13#include <linux/init.h>
14
15#include <linux/time.h>
16#include <linux/kernel.h>
17#include <linux/mm.h>
18#include <linux/string.h>
19#include <linux/stat.h>
20#include <linux/errno.h>
21#include <linux/unistd.h>
22#include <linux/sunrpc/clnt.h>
23#include <linux/sunrpc/stats.h>
24#include <linux/nfs_fs.h>
25#include <linux/nfs_mount.h>
26#include <linux/nfs4_mount.h>
27#include <linux/lockd/bind.h>
David Howells54ceac42006-08-22 20:06:13 -040028#include <linux/seq_file.h>
29#include <linux/mount.h>
30#include <linux/nfs_idmap.h>
31#include <linux/vfs.h>
32#include <linux/namei.h>
David Howells738a3512006-07-30 14:58:27 -040033#include <linux/security.h>
David Howells54ceac42006-08-22 20:06:13 -040034
35#include <asm/system.h>
36#include <asm/uaccess.h>
37
38#include "nfs4_fs.h"
39#include "delegation.h"
40#include "internal.h"
41
42#define NFSDBG_FACILITY NFSDBG_CLIENT
David Howells54ceac42006-08-22 20:06:13 -040043
44/*
Trond Myklebustb09b9412007-10-25 13:56:10 -040045 * Set the superblock root dentry.
46 * Note that this function frees the inode in case of error.
47 */
48static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode)
49{
50 /* The mntroot acts as the dummy root dentry for this superblock */
51 if (sb->s_root == NULL) {
52 sb->s_root = d_alloc_root(inode);
53 if (sb->s_root == NULL) {
54 iput(inode);
55 return -ENOMEM;
56 }
Al Viro7de9c6e2010-10-23 11:11:40 -040057 ihold(inode);
Trond Myklebusta10db502007-12-12 11:12:15 -050058 /*
59 * Ensure that this dentry is invisible to d_find_alias().
60 * Otherwise, it may be spliced into the tree by
61 * d_materialise_unique if a parent directory from the same
62 * filesystem gets mounted at a later time.
63 * This again causes shrink_dcache_for_umount_subtree() to
64 * Oops, since the test for IS_ROOT() will fail.
65 */
66 spin_lock(&dcache_lock);
67 list_del_init(&sb->s_root->d_alias);
68 spin_unlock(&dcache_lock);
Trond Myklebustb09b9412007-10-25 13:56:10 -040069 }
70 return 0;
71}
72
73/*
David Howells54ceac42006-08-22 20:06:13 -040074 * get an NFS2/NFS3 root dentry from the root filehandle
75 */
76struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
77{
78 struct nfs_server *server = NFS_SB(sb);
79 struct nfs_fsinfo fsinfo;
Trond Myklebust8bac9db2010-04-16 16:22:48 -040080 struct dentry *ret;
David Howells54ceac42006-08-22 20:06:13 -040081 struct inode *inode;
82 int error;
83
David Howells54ceac42006-08-22 20:06:13 -040084 /* get the actual root for this mount */
Trond Myklebust8bac9db2010-04-16 16:22:48 -040085 fsinfo.fattr = nfs_alloc_fattr();
86 if (fsinfo.fattr == NULL)
87 return ERR_PTR(-ENOMEM);
David Howells54ceac42006-08-22 20:06:13 -040088
89 error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
90 if (error < 0) {
91 dprintk("nfs_get_root: getattr error = %d\n", -error);
Trond Myklebust8bac9db2010-04-16 16:22:48 -040092 ret = ERR_PTR(error);
93 goto out;
David Howells54ceac42006-08-22 20:06:13 -040094 }
95
96 inode = nfs_fhget(sb, mntfh, fsinfo.fattr);
97 if (IS_ERR(inode)) {
98 dprintk("nfs_get_root: get root inode failed\n");
Trond Myklebust8bac9db2010-04-16 16:22:48 -040099 ret = ERR_CAST(inode);
100 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400101 }
102
Trond Myklebustb09b9412007-10-25 13:56:10 -0400103 error = nfs_superblock_set_dummy_root(sb, inode);
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400104 if (error != 0) {
105 ret = ERR_PTR(error);
106 goto out;
107 }
Trond Myklebustb09b9412007-10-25 13:56:10 -0400108
David Howells54ceac42006-08-22 20:06:13 -0400109 /* root dentries normally start off anonymous and get spliced in later
110 * if the dentry tree reaches them; however if the dentry already
111 * exists, we'll pick it up at this point and use it as the root
112 */
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400113 ret = d_obtain_alias(inode);
114 if (IS_ERR(ret)) {
David Howells54ceac42006-08-22 20:06:13 -0400115 dprintk("nfs_get_root: get root dentry failed\n");
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400116 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400117 }
118
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400119 security_d_instantiate(ret, inode);
David Howells738a3512006-07-30 14:58:27 -0400120
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400121 if (ret->d_op == NULL)
122 ret->d_op = server->nfs_client->rpc_ops->dentry_ops;
123out:
124 nfs_free_fattr(fsinfo.fattr);
125 return ret;
David Howells54ceac42006-08-22 20:06:13 -0400126}
127
128#ifdef CONFIG_NFS_V4
129
Trond Myklebust815409d2010-04-16 16:22:46 -0400130int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh)
David Howells54ceac42006-08-22 20:06:13 -0400131{
132 struct nfs_fsinfo fsinfo;
Trond Myklebust815409d2010-04-16 16:22:46 -0400133 int ret = -ENOMEM;
David Howells54ceac42006-08-22 20:06:13 -0400134
Trond Myklebust815409d2010-04-16 16:22:46 -0400135 dprintk("--> nfs4_get_rootfh()\n");
David Howells54ceac42006-08-22 20:06:13 -0400136
Trond Myklebust815409d2010-04-16 16:22:46 -0400137 fsinfo.fattr = nfs_alloc_fattr();
138 if (fsinfo.fattr == NULL)
139 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400140
141 /* Start by getting the root filehandle from the server */
142 ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
143 if (ret < 0) {
Trond Myklebust815409d2010-04-16 16:22:46 -0400144 dprintk("nfs4_get_rootfh: getroot error = %d\n", -ret);
145 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400146 }
147
Andy Adamsonf799bdb2010-06-16 09:51:02 -0400148 if (!(fsinfo.fattr->valid & NFS_ATTR_FATTR_TYPE)
Trond Myklebust815409d2010-04-16 16:22:46 -0400149 || !S_ISDIR(fsinfo.fattr->mode)) {
150 printk(KERN_ERR "nfs4_get_rootfh:"
David Howells54ceac42006-08-22 20:06:13 -0400151 " getroot encountered non-directory\n");
Trond Myklebust815409d2010-04-16 16:22:46 -0400152 ret = -ENOTDIR;
153 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400154 }
155
Trond Myklebust815409d2010-04-16 16:22:46 -0400156 if (fsinfo.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
157 printk(KERN_ERR "nfs4_get_rootfh:"
David Howells54ceac42006-08-22 20:06:13 -0400158 " getroot obtained referral\n");
Trond Myklebust815409d2010-04-16 16:22:46 -0400159 ret = -EREMOTE;
160 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400161 }
162
Trond Myklebust815409d2010-04-16 16:22:46 -0400163 memcpy(&server->fsid, &fsinfo.fattr->fsid, sizeof(server->fsid));
164out:
165 nfs_free_fattr(fsinfo.fattr);
166 dprintk("<-- nfs4_get_rootfh() = %d\n", ret);
167 return ret;
David Howells54ceac42006-08-22 20:06:13 -0400168}
169
170/*
171 * get an NFS4 root dentry from the root filehandle
172 */
173struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
174{
175 struct nfs_server *server = NFS_SB(sb);
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400176 struct nfs_fattr *fattr = NULL;
177 struct dentry *ret;
David Howells54ceac42006-08-22 20:06:13 -0400178 struct inode *inode;
179 int error;
180
181 dprintk("--> nfs4_get_root()\n");
182
David Howells54ceac42006-08-22 20:06:13 -0400183 /* get the info about the server and filesystem */
184 error = nfs4_server_capabilities(server, mntfh);
185 if (error < 0) {
186 dprintk("nfs_get_root: getcaps error = %d\n",
187 -error);
188 return ERR_PTR(error);
189 }
190
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400191 fattr = nfs_alloc_fattr();
192 if (fattr == NULL)
193 return ERR_PTR(-ENOMEM);;
194
David Howells54ceac42006-08-22 20:06:13 -0400195 /* get the actual root for this mount */
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400196 error = server->nfs_client->rpc_ops->getattr(server, mntfh, fattr);
David Howells54ceac42006-08-22 20:06:13 -0400197 if (error < 0) {
198 dprintk("nfs_get_root: getattr error = %d\n", -error);
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400199 ret = ERR_PTR(error);
200 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400201 }
202
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400203 inode = nfs_fhget(sb, mntfh, fattr);
David Howells54ceac42006-08-22 20:06:13 -0400204 if (IS_ERR(inode)) {
205 dprintk("nfs_get_root: get root inode failed\n");
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400206 ret = ERR_CAST(inode);
207 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400208 }
209
Trond Myklebustb09b9412007-10-25 13:56:10 -0400210 error = nfs_superblock_set_dummy_root(sb, inode);
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400211 if (error != 0) {
212 ret = ERR_PTR(error);
213 goto out;
214 }
Trond Myklebustb09b9412007-10-25 13:56:10 -0400215
David Howells54ceac42006-08-22 20:06:13 -0400216 /* root dentries normally start off anonymous and get spliced in later
217 * if the dentry tree reaches them; however if the dentry already
218 * exists, we'll pick it up at this point and use it as the root
219 */
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400220 ret = d_obtain_alias(inode);
221 if (IS_ERR(ret)) {
David Howells54ceac42006-08-22 20:06:13 -0400222 dprintk("nfs_get_root: get root dentry failed\n");
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400223 goto out;
David Howells54ceac42006-08-22 20:06:13 -0400224 }
225
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400226 security_d_instantiate(ret, inode);
David Howells738a3512006-07-30 14:58:27 -0400227
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400228 if (ret->d_op == NULL)
229 ret->d_op = server->nfs_client->rpc_ops->dentry_ops;
David Howells54ceac42006-08-22 20:06:13 -0400230
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400231out:
232 nfs_free_fattr(fattr);
David Howells54ceac42006-08-22 20:06:13 -0400233 dprintk("<-- nfs4_get_root()\n");
Trond Myklebust8bac9db2010-04-16 16:22:48 -0400234 return ret;
David Howells54ceac42006-08-22 20:06:13 -0400235}
236
237#endif /* CONFIG_NFS_V4 */