1 /* 2 * Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com> 3 */ 4 #include <linux/init.h> 5 #include <linux/module.h> 6 #include <linux/nfs_idmap.h> 7 #include <linux/nfs4_mount.h> 8 #include <linux/nfs_fs.h> 9 #include "internal.h" 10 #include "nfs4_fs.h" 11 12 #define NFSDBG_FACILITY NFSDBG_VFS 13 14 static struct dentry *nfs4_remote_mount(struct file_system_type *fs_type, 15 int flags, const char *dev_name, void *raw_data); 16 static struct dentry *nfs4_xdev_mount(struct file_system_type *fs_type, 17 int flags, const char *dev_name, void *raw_data); 18 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type, 19 int flags, const char *dev_name, void *raw_data); 20 static struct dentry *nfs4_remote_referral_mount(struct file_system_type *fs_type, 21 int flags, const char *dev_name, void *raw_data); 22 23 static struct file_system_type nfs4_fs_type = { 24 .owner = THIS_MODULE, 25 .name = "nfs4", 26 .mount = nfs_fs_mount, 27 .kill_sb = nfs_kill_super, 28 .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA, 29 }; 30 31 static struct file_system_type nfs4_remote_fs_type = { 32 .owner = THIS_MODULE, 33 .name = "nfs4", 34 .mount = nfs4_remote_mount, 35 .kill_sb = nfs_kill_super, 36 .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA, 37 }; 38 39 struct file_system_type nfs4_xdev_fs_type = { 40 .owner = THIS_MODULE, 41 .name = "nfs4", 42 .mount = nfs4_xdev_mount, 43 .kill_sb = nfs_kill_super, 44 .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA, 45 }; 46 47 static struct file_system_type nfs4_remote_referral_fs_type = { 48 .owner = THIS_MODULE, 49 .name = "nfs4", 50 .mount = nfs4_remote_referral_mount, 51 .kill_sb = nfs_kill_super, 52 .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA, 53 }; 54 55 struct file_system_type nfs4_referral_fs_type = { 56 .owner = THIS_MODULE, 57 .name = "nfs4", 58 .mount = nfs4_referral_mount, 59 .kill_sb = nfs_kill_super, 60 .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA, 61 }; 62 63 static const struct super_operations nfs4_sops = { 64 .alloc_inode = nfs_alloc_inode, 65 .destroy_inode = nfs_destroy_inode, 66 .write_inode = nfs4_write_inode, 67 .put_super = nfs_put_super, 68 .statfs = nfs_statfs, 69 .evict_inode = nfs4_evict_inode, 70 .umount_begin = nfs_umount_begin, 71 .show_options = nfs_show_options, 72 .show_devname = nfs_show_devname, 73 .show_path = nfs_show_path, 74 .show_stats = nfs_show_stats, 75 .remount_fs = nfs_remount, 76 }; 77 78 /* 79 * Set up an NFS4 superblock 80 */ 81 static void nfs4_fill_super(struct super_block *sb, 82 struct nfs_mount_info *mount_info) 83 { 84 sb->s_time_gran = 1; 85 sb->s_op = &nfs4_sops; 86 /* 87 * The VFS shouldn't apply the umask to mode bits. We will do 88 * so ourselves when necessary. 89 */ 90 sb->s_flags |= MS_POSIXACL; 91 sb->s_xattr = nfs4_xattr_handlers; 92 nfs_initialise_sb(sb); 93 } 94 95 /* 96 * Get the superblock for the NFS4 root partition 97 */ 98 static struct dentry * 99 nfs4_remote_mount(struct file_system_type *fs_type, int flags, 100 const char *dev_name, void *info) 101 { 102 struct nfs_mount_info *mount_info = info; 103 struct nfs_server *server; 104 struct dentry *mntroot = ERR_PTR(-ENOMEM); 105 106 mount_info->fill_super = nfs4_fill_super; 107 mount_info->set_security = nfs_set_sb_security; 108 109 /* Get a volume representation */ 110 server = nfs4_create_server(mount_info->parsed, mount_info->mntfh); 111 if (IS_ERR(server)) { 112 mntroot = ERR_CAST(server); 113 goto out; 114 } 115 116 mntroot = nfs_fs_mount_common(fs_type, server, flags, dev_name, mount_info); 117 118 out: 119 return mntroot; 120 } 121 122 static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type, 123 int flags, void *data, const char *hostname) 124 { 125 struct vfsmount *root_mnt; 126 char *root_devname; 127 size_t len; 128 129 len = strlen(hostname) + 5; 130 root_devname = kmalloc(len, GFP_KERNEL); 131 if (root_devname == NULL) 132 return ERR_PTR(-ENOMEM); 133 /* Does hostname needs to be enclosed in brackets? */ 134 if (strchr(hostname, ':')) 135 snprintf(root_devname, len, "[%s]:/", hostname); 136 else 137 snprintf(root_devname, len, "%s:/", hostname); 138 root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data); 139 kfree(root_devname); 140 return root_mnt; 141 } 142 143 struct nfs_referral_count { 144 struct list_head list; 145 const struct task_struct *task; 146 unsigned int referral_count; 147 }; 148 149 static LIST_HEAD(nfs_referral_count_list); 150 static DEFINE_SPINLOCK(nfs_referral_count_list_lock); 151 152 static struct nfs_referral_count *nfs_find_referral_count(void) 153 { 154 struct nfs_referral_count *p; 155 156 list_for_each_entry(p, &nfs_referral_count_list, list) { 157 if (p->task == current) 158 return p; 159 } 160 return NULL; 161 } 162 163 #define NFS_MAX_NESTED_REFERRALS 2 164 165 static int nfs_referral_loop_protect(void) 166 { 167 struct nfs_referral_count *p, *new; 168 int ret = -ENOMEM; 169 170 new = kmalloc(sizeof(*new), GFP_KERNEL); 171 if (!new) 172 goto out; 173 new->task = current; 174 new->referral_count = 1; 175 176 ret = 0; 177 spin_lock(&nfs_referral_count_list_lock); 178 p = nfs_find_referral_count(); 179 if (p != NULL) { 180 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS) 181 ret = -ELOOP; 182 else 183 p->referral_count++; 184 } else { 185 list_add(&new->list, &nfs_referral_count_list); 186 new = NULL; 187 } 188 spin_unlock(&nfs_referral_count_list_lock); 189 kfree(new); 190 out: 191 return ret; 192 } 193 194 static void nfs_referral_loop_unprotect(void) 195 { 196 struct nfs_referral_count *p; 197 198 spin_lock(&nfs_referral_count_list_lock); 199 p = nfs_find_referral_count(); 200 p->referral_count--; 201 if (p->referral_count == 0) 202 list_del(&p->list); 203 else 204 p = NULL; 205 spin_unlock(&nfs_referral_count_list_lock); 206 kfree(p); 207 } 208 209 static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt, 210 const char *export_path) 211 { 212 struct dentry *dentry; 213 int err; 214 215 if (IS_ERR(root_mnt)) 216 return ERR_CAST(root_mnt); 217 218 err = nfs_referral_loop_protect(); 219 if (err) { 220 mntput(root_mnt); 221 return ERR_PTR(err); 222 } 223 224 dentry = mount_subtree(root_mnt, export_path); 225 nfs_referral_loop_unprotect(); 226 227 return dentry; 228 } 229 230 struct dentry *nfs4_try_mount(int flags, const char *dev_name, 231 struct nfs_mount_info *mount_info) 232 { 233 char *export_path; 234 struct vfsmount *root_mnt; 235 struct dentry *res; 236 struct nfs_parsed_mount_data *data = mount_info->parsed; 237 238 dfprintk(MOUNT, "--> nfs4_try_mount()\n"); 239 240 mount_info->fill_super = nfs4_fill_super; 241 242 export_path = data->nfs_server.export_path; 243 data->nfs_server.export_path = "/"; 244 root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info, 245 data->nfs_server.hostname); 246 data->nfs_server.export_path = export_path; 247 248 res = nfs_follow_remote_path(root_mnt, export_path); 249 250 dfprintk(MOUNT, "<-- nfs4_try_mount() = %ld%s\n", 251 IS_ERR(res) ? PTR_ERR(res) : 0, 252 IS_ERR(res) ? " [error]" : ""); 253 return res; 254 } 255 256 /* 257 * Clone an NFS4 server record on xdev traversal (FSID-change) 258 */ 259 static struct dentry * 260 nfs4_xdev_mount(struct file_system_type *fs_type, int flags, 261 const char *dev_name, void *raw_data) 262 { 263 struct nfs_mount_info mount_info = { 264 .fill_super = nfs_clone_super, 265 .set_security = nfs_clone_sb_security, 266 .cloned = raw_data, 267 }; 268 return nfs_xdev_mount_common(&nfs4_fs_type, flags, dev_name, &mount_info); 269 } 270 271 static struct dentry * 272 nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags, 273 const char *dev_name, void *raw_data) 274 { 275 struct nfs_mount_info mount_info = { 276 .fill_super = nfs4_fill_super, 277 .set_security = nfs_clone_sb_security, 278 .cloned = raw_data, 279 }; 280 struct nfs_server *server; 281 struct dentry *mntroot = ERR_PTR(-ENOMEM); 282 283 dprintk("--> nfs4_referral_get_sb()\n"); 284 285 mount_info.mntfh = nfs_alloc_fhandle(); 286 if (mount_info.cloned == NULL || mount_info.mntfh == NULL) 287 goto out; 288 289 /* create a new volume representation */ 290 server = nfs4_create_referral_server(mount_info.cloned, mount_info.mntfh); 291 if (IS_ERR(server)) { 292 mntroot = ERR_CAST(server); 293 goto out; 294 } 295 296 mntroot = nfs_fs_mount_common(&nfs4_fs_type, server, flags, dev_name, &mount_info); 297 out: 298 nfs_free_fhandle(mount_info.mntfh); 299 return mntroot; 300 } 301 302 /* 303 * Create an NFS4 server record on referral traversal 304 */ 305 static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type, 306 int flags, const char *dev_name, void *raw_data) 307 { 308 struct nfs_clone_mount *data = raw_data; 309 char *export_path; 310 struct vfsmount *root_mnt; 311 struct dentry *res; 312 313 dprintk("--> nfs4_referral_mount()\n"); 314 315 export_path = data->mnt_path; 316 data->mnt_path = "/"; 317 318 root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type, 319 flags, data, data->hostname); 320 data->mnt_path = export_path; 321 322 res = nfs_follow_remote_path(root_mnt, export_path); 323 dprintk("<-- nfs4_referral_mount() = %ld%s\n", 324 IS_ERR(res) ? PTR_ERR(res) : 0, 325 IS_ERR(res) ? " [error]" : ""); 326 return res; 327 } 328 329 330 int __init init_nfs_v4(void) 331 { 332 int err; 333 334 err = nfs_idmap_init(); 335 if (err) 336 goto out; 337 338 err = nfs4_register_sysctl(); 339 if (err) 340 goto out1; 341 342 err = register_filesystem(&nfs4_fs_type); 343 if (err < 0) 344 goto out2; 345 346 return 0; 347 out2: 348 nfs4_unregister_sysctl(); 349 out1: 350 nfs_idmap_quit(); 351 out: 352 return err; 353 } 354 355 void __exit exit_nfs_v4(void) 356 { 357 unregister_filesystem(&nfs4_fs_type); 358 nfs4_unregister_sysctl(); 359 nfs_idmap_quit(); 360 } 361