1 /* 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 12 #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> 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> 34 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 43 44 /* 45 * Set the superblock root dentry. 46 * Note that this function frees the inode in case of error. 47 */ 48 static 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 } 57 ihold(inode); 58 /* 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(&sb->s_root->d_inode->i_lock); 67 spin_lock(&sb->s_root->d_lock); 68 list_del_init(&sb->s_root->d_alias); 69 spin_unlock(&sb->s_root->d_lock); 70 spin_unlock(&sb->s_root->d_inode->i_lock); 71 } 72 return 0; 73 } 74 75 /* 76 * get an NFS2/NFS3 root dentry from the root filehandle 77 */ 78 struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh, 79 const char *devname) 80 { 81 struct nfs_server *server = NFS_SB(sb); 82 struct nfs_fsinfo fsinfo; 83 struct dentry *ret; 84 struct inode *inode; 85 void *name = kstrdup(devname, GFP_KERNEL); 86 int error; 87 88 if (!name) 89 return ERR_PTR(-ENOMEM); 90 91 /* get the actual root for this mount */ 92 fsinfo.fattr = nfs_alloc_fattr(); 93 if (fsinfo.fattr == NULL) { 94 kfree(name); 95 return ERR_PTR(-ENOMEM); 96 } 97 98 error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); 99 if (error < 0) { 100 dprintk("nfs_get_root: getattr error = %d\n", -error); 101 ret = ERR_PTR(error); 102 goto out; 103 } 104 105 inode = nfs_fhget(sb, mntfh, fsinfo.fattr); 106 if (IS_ERR(inode)) { 107 dprintk("nfs_get_root: get root inode failed\n"); 108 ret = ERR_CAST(inode); 109 goto out; 110 } 111 112 error = nfs_superblock_set_dummy_root(sb, inode); 113 if (error != 0) { 114 ret = ERR_PTR(error); 115 goto out; 116 } 117 118 /* root dentries normally start off anonymous and get spliced in later 119 * if the dentry tree reaches them; however if the dentry already 120 * exists, we'll pick it up at this point and use it as the root 121 */ 122 ret = d_obtain_alias(inode); 123 if (IS_ERR(ret)) { 124 dprintk("nfs_get_root: get root dentry failed\n"); 125 goto out; 126 } 127 128 security_d_instantiate(ret, inode); 129 spin_lock(&ret->d_lock); 130 if (IS_ROOT(ret) && !(ret->d_flags & DCACHE_NFSFS_RENAMED)) { 131 ret->d_fsdata = name; 132 name = NULL; 133 } 134 spin_unlock(&ret->d_lock); 135 out: 136 if (name) 137 kfree(name); 138 nfs_free_fattr(fsinfo.fattr); 139 return ret; 140 } 141 142 #ifdef CONFIG_NFS_V4 143 144 int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh) 145 { 146 struct nfs_fsinfo fsinfo; 147 int ret = -ENOMEM; 148 149 dprintk("--> nfs4_get_rootfh()\n"); 150 151 fsinfo.fattr = nfs_alloc_fattr(); 152 if (fsinfo.fattr == NULL) 153 goto out; 154 155 /* Start by getting the root filehandle from the server */ 156 ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); 157 if (ret < 0) { 158 dprintk("nfs4_get_rootfh: getroot error = %d\n", -ret); 159 goto out; 160 } 161 162 if (!(fsinfo.fattr->valid & NFS_ATTR_FATTR_TYPE) 163 || !S_ISDIR(fsinfo.fattr->mode)) { 164 printk(KERN_ERR "nfs4_get_rootfh:" 165 " getroot encountered non-directory\n"); 166 ret = -ENOTDIR; 167 goto out; 168 } 169 170 if (fsinfo.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) { 171 printk(KERN_ERR "nfs4_get_rootfh:" 172 " getroot obtained referral\n"); 173 ret = -EREMOTE; 174 goto out; 175 } 176 177 memcpy(&server->fsid, &fsinfo.fattr->fsid, sizeof(server->fsid)); 178 out: 179 nfs_free_fattr(fsinfo.fattr); 180 dprintk("<-- nfs4_get_rootfh() = %d\n", ret); 181 return ret; 182 } 183 184 /* 185 * get an NFS4 root dentry from the root filehandle 186 */ 187 struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh, 188 const char *devname) 189 { 190 struct nfs_server *server = NFS_SB(sb); 191 struct nfs_fattr *fattr = NULL; 192 struct dentry *ret; 193 struct inode *inode; 194 void *name = kstrdup(devname, GFP_KERNEL); 195 int error; 196 197 dprintk("--> nfs4_get_root()\n"); 198 199 if (!name) 200 return ERR_PTR(-ENOMEM); 201 202 /* get the info about the server and filesystem */ 203 error = nfs4_server_capabilities(server, mntfh); 204 if (error < 0) { 205 dprintk("nfs_get_root: getcaps error = %d\n", 206 -error); 207 kfree(name); 208 return ERR_PTR(error); 209 } 210 211 fattr = nfs_alloc_fattr(); 212 if (fattr == NULL) { 213 kfree(name); 214 return ERR_PTR(-ENOMEM); 215 } 216 217 /* get the actual root for this mount */ 218 error = server->nfs_client->rpc_ops->getattr(server, mntfh, fattr); 219 if (error < 0) { 220 dprintk("nfs_get_root: getattr error = %d\n", -error); 221 ret = ERR_PTR(error); 222 goto out; 223 } 224 225 inode = nfs_fhget(sb, mntfh, fattr); 226 if (IS_ERR(inode)) { 227 dprintk("nfs_get_root: get root inode failed\n"); 228 ret = ERR_CAST(inode); 229 goto out; 230 } 231 232 error = nfs_superblock_set_dummy_root(sb, inode); 233 if (error != 0) { 234 ret = ERR_PTR(error); 235 goto out; 236 } 237 238 /* root dentries normally start off anonymous and get spliced in later 239 * if the dentry tree reaches them; however if the dentry already 240 * exists, we'll pick it up at this point and use it as the root 241 */ 242 ret = d_obtain_alias(inode); 243 if (IS_ERR(ret)) { 244 dprintk("nfs_get_root: get root dentry failed\n"); 245 goto out; 246 } 247 248 security_d_instantiate(ret, inode); 249 spin_lock(&ret->d_lock); 250 if (IS_ROOT(ret) && !(ret->d_flags & DCACHE_NFSFS_RENAMED)) { 251 ret->d_fsdata = name; 252 name = NULL; 253 } 254 spin_unlock(&ret->d_lock); 255 out: 256 if (name) 257 kfree(name); 258 nfs_free_fattr(fattr); 259 dprintk("<-- nfs4_get_root()\n"); 260 return ret; 261 } 262 263 #endif /* CONFIG_NFS_V4 */ 264