1 /* getroot.c: get the root dentry for an NFS mount
3 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/module.h>
13 #include <linux/init.h>
15 #include <linux/time.h>
16 #include <linux/kernel.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>
28 #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>
33 #include <linux/security.h>
35 #include <asm/system.h>
36 #include <asm/uaccess.h>
39 #include "delegation.h"
42 #define NFSDBG_FACILITY NFSDBG_CLIENT
45 * Set the superblock root dentry.
46 * Note that this function frees the inode in case of error.
48 static int nfs_superblock_set_dummy_root(struct super_block
*sb
, struct inode
*inode
)
50 /* The mntroot acts as the dummy root dentry for this superblock */
51 if (sb
->s_root
== NULL
) {
52 sb
->s_root
= d_make_root(inode
);
53 if (sb
->s_root
== NULL
)
57 * Ensure that this dentry is invisible to d_find_alias().
58 * Otherwise, it may be spliced into the tree by
59 * d_materialise_unique if a parent directory from the same
60 * filesystem gets mounted at a later time.
61 * This again causes shrink_dcache_for_umount_subtree() to
62 * Oops, since the test for IS_ROOT() will fail.
64 spin_lock(&sb
->s_root
->d_inode
->i_lock
);
65 spin_lock(&sb
->s_root
->d_lock
);
66 list_del_init(&sb
->s_root
->d_alias
);
67 spin_unlock(&sb
->s_root
->d_lock
);
68 spin_unlock(&sb
->s_root
->d_inode
->i_lock
);
74 * get an NFS2/NFS3 root dentry from the root filehandle
76 struct dentry
*nfs_get_root(struct super_block
*sb
, struct nfs_fh
*mntfh
,
79 struct nfs_server
*server
= NFS_SB(sb
);
80 struct nfs_fsinfo fsinfo
;
83 void *name
= kstrdup(devname
, GFP_KERNEL
);
87 return ERR_PTR(-ENOMEM
);
89 /* get the actual root for this mount */
90 fsinfo
.fattr
= nfs_alloc_fattr();
91 if (fsinfo
.fattr
== NULL
) {
93 return ERR_PTR(-ENOMEM
);
96 error
= server
->nfs_client
->rpc_ops
->getroot(server
, mntfh
, &fsinfo
);
98 dprintk("nfs_get_root: getattr error = %d\n", -error
);
103 inode
= nfs_fhget(sb
, mntfh
, fsinfo
.fattr
);
105 dprintk("nfs_get_root: get root inode failed\n");
106 ret
= ERR_CAST(inode
);
110 error
= nfs_superblock_set_dummy_root(sb
, inode
);
112 ret
= ERR_PTR(error
);
116 /* root dentries normally start off anonymous and get spliced in later
117 * if the dentry tree reaches them; however if the dentry already
118 * exists, we'll pick it up at this point and use it as the root
120 ret
= d_obtain_alias(inode
);
122 dprintk("nfs_get_root: get root dentry failed\n");
126 security_d_instantiate(ret
, inode
);
127 spin_lock(&ret
->d_lock
);
128 if (IS_ROOT(ret
) && !(ret
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
129 ret
->d_fsdata
= name
;
132 spin_unlock(&ret
->d_lock
);
136 nfs_free_fattr(fsinfo
.fattr
);
142 int nfs4_get_rootfh(struct nfs_server
*server
, struct nfs_fh
*mntfh
)
144 struct nfs_fsinfo fsinfo
;
147 dprintk("--> nfs4_get_rootfh()\n");
149 fsinfo
.fattr
= nfs_alloc_fattr();
150 if (fsinfo
.fattr
== NULL
)
153 /* Start by getting the root filehandle from the server */
154 ret
= server
->nfs_client
->rpc_ops
->getroot(server
, mntfh
, &fsinfo
);
156 dprintk("nfs4_get_rootfh: getroot error = %d\n", -ret
);
160 if (!(fsinfo
.fattr
->valid
& NFS_ATTR_FATTR_TYPE
)
161 || !S_ISDIR(fsinfo
.fattr
->mode
)) {
162 printk(KERN_ERR
"nfs4_get_rootfh:"
163 " getroot encountered non-directory\n");
168 if (fsinfo
.fattr
->valid
& NFS_ATTR_FATTR_V4_REFERRAL
) {
169 printk(KERN_ERR
"nfs4_get_rootfh:"
170 " getroot obtained referral\n");
175 memcpy(&server
->fsid
, &fsinfo
.fattr
->fsid
, sizeof(server
->fsid
));
177 nfs_free_fattr(fsinfo
.fattr
);
178 dprintk("<-- nfs4_get_rootfh() = %d\n", ret
);
183 * get an NFS4 root dentry from the root filehandle
185 struct dentry
*nfs4_get_root(struct super_block
*sb
, struct nfs_fh
*mntfh
,
188 struct nfs_server
*server
= NFS_SB(sb
);
189 struct nfs_fattr
*fattr
= NULL
;
192 void *name
= kstrdup(devname
, GFP_KERNEL
);
195 dprintk("--> nfs4_get_root()\n");
198 return ERR_PTR(-ENOMEM
);
200 /* get the info about the server and filesystem */
201 error
= nfs4_server_capabilities(server
, mntfh
);
203 dprintk("nfs_get_root: getcaps error = %d\n",
206 return ERR_PTR(error
);
209 fattr
= nfs_alloc_fattr();
212 return ERR_PTR(-ENOMEM
);
215 /* get the actual root for this mount */
216 error
= server
->nfs_client
->rpc_ops
->getattr(server
, mntfh
, fattr
);
218 dprintk("nfs_get_root: getattr error = %d\n", -error
);
219 ret
= ERR_PTR(error
);
223 if (fattr
->valid
& NFS_ATTR_FATTR_FSID
&&
224 !nfs_fsid_equal(&server
->fsid
, &fattr
->fsid
))
225 memcpy(&server
->fsid
, &fattr
->fsid
, sizeof(server
->fsid
));
227 inode
= nfs_fhget(sb
, mntfh
, fattr
);
229 dprintk("nfs_get_root: get root inode failed\n");
230 ret
= ERR_CAST(inode
);
234 error
= nfs_superblock_set_dummy_root(sb
, inode
);
236 ret
= ERR_PTR(error
);
240 /* root dentries normally start off anonymous and get spliced in later
241 * if the dentry tree reaches them; however if the dentry already
242 * exists, we'll pick it up at this point and use it as the root
244 ret
= d_obtain_alias(inode
);
246 dprintk("nfs_get_root: get root dentry failed\n");
250 security_d_instantiate(ret
, inode
);
251 spin_lock(&ret
->d_lock
);
252 if (IS_ROOT(ret
) && !(ret
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
253 ret
->d_fsdata
= name
;
256 spin_unlock(&ret
->d_lock
);
260 nfs_free_fattr(fattr
);
261 dprintk("<-- nfs4_get_root()\n");
265 #endif /* CONFIG_NFS_V4 */