1 /* 2 FUSE: Filesystem in Userspace 3 Copyright (C) 2001-2006 Miklos Szeredi <miklos@szeredi.hu> 4 5 This program can be distributed under the terms of the GNU GPL. 6 See the file COPYING. 7 */ 8 9 #include <linux/fuse.h> 10 #include <linux/fs.h> 11 #include <linux/mount.h> 12 #include <linux/wait.h> 13 #include <linux/list.h> 14 #include <linux/spinlock.h> 15 #include <linux/mm.h> 16 #include <linux/backing-dev.h> 17 #include <linux/mutex.h> 18 19 /** Max number of pages that can be used in a single read request */ 20 #define FUSE_MAX_PAGES_PER_REQ 32 21 22 /** Maximum number of outstanding background requests */ 23 #define FUSE_MAX_BACKGROUND 12 24 25 /** Congestion starts at 75% of maximum */ 26 #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100) 27 28 /** It could be as large as PATH_MAX, but would that have any uses? */ 29 #define FUSE_NAME_MAX 1024 30 31 /** Number of dentries for each connection in the control filesystem */ 32 #define FUSE_CTL_NUM_DENTRIES 3 33 34 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem 35 module will check permissions based on the file mode. Otherwise no 36 permission checking is done in the kernel */ 37 #define FUSE_DEFAULT_PERMISSIONS (1 << 0) 38 39 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user 40 doing the mount will be allowed to access the filesystem */ 41 #define FUSE_ALLOW_OTHER (1 << 1) 42 43 /** List of active connections */ 44 extern struct list_head fuse_conn_list; 45 46 /** Global mutex protecting fuse_conn_list and the control filesystem */ 47 extern struct mutex fuse_mutex; 48 49 /** FUSE inode */ 50 struct fuse_inode { 51 /** Inode data */ 52 struct inode inode; 53 54 /** Unique ID, which identifies the inode between userspace 55 * and kernel */ 56 u64 nodeid; 57 58 /** Number of lookups on this inode */ 59 u64 nlookup; 60 61 /** The request used for sending the FORGET message */ 62 struct fuse_req *forget_req; 63 64 /** Time in jiffies until the file attributes are valid */ 65 u64 i_time; 66 67 /** The sticky bit in inode->i_mode may have been removed, so 68 preserve the original mode */ 69 mode_t orig_i_mode; 70 71 /** Version of last attribute change */ 72 u64 attr_version; 73 74 /** Files usable in writepage. Protected by fc->lock */ 75 struct list_head write_files; 76 }; 77 78 /** FUSE specific file data */ 79 struct fuse_file { 80 /** Request reserved for flush and release */ 81 struct fuse_req *reserved_req; 82 83 /** File handle used by userspace */ 84 u64 fh; 85 86 /** Refcount */ 87 atomic_t count; 88 89 /** Entry on inode's write_files list */ 90 struct list_head write_entry; 91 }; 92 93 /** One input argument of a request */ 94 struct fuse_in_arg { 95 unsigned size; 96 const void *value; 97 }; 98 99 /** The request input */ 100 struct fuse_in { 101 /** The request header */ 102 struct fuse_in_header h; 103 104 /** True if the data for the last argument is in req->pages */ 105 unsigned argpages:1; 106 107 /** Number of arguments */ 108 unsigned numargs; 109 110 /** Array of arguments */ 111 struct fuse_in_arg args[3]; 112 }; 113 114 /** One output argument of a request */ 115 struct fuse_arg { 116 unsigned size; 117 void *value; 118 }; 119 120 /** The request output */ 121 struct fuse_out { 122 /** Header returned from userspace */ 123 struct fuse_out_header h; 124 125 /* 126 * The following bitfields are not changed during the request 127 * processing 128 */ 129 130 /** Last argument is variable length (can be shorter than 131 arg->size) */ 132 unsigned argvar:1; 133 134 /** Last argument is a list of pages to copy data to */ 135 unsigned argpages:1; 136 137 /** Zero partially or not copied pages */ 138 unsigned page_zeroing:1; 139 140 /** Number or arguments */ 141 unsigned numargs; 142 143 /** Array of arguments */ 144 struct fuse_arg args[3]; 145 }; 146 147 /** The request state */ 148 enum fuse_req_state { 149 FUSE_REQ_INIT = 0, 150 FUSE_REQ_PENDING, 151 FUSE_REQ_READING, 152 FUSE_REQ_SENT, 153 FUSE_REQ_WRITING, 154 FUSE_REQ_FINISHED 155 }; 156 157 struct fuse_conn; 158 159 /** 160 * A request to the client 161 */ 162 struct fuse_req { 163 /** This can be on either pending processing or io lists in 164 fuse_conn */ 165 struct list_head list; 166 167 /** Entry on the interrupts list */ 168 struct list_head intr_entry; 169 170 /** refcount */ 171 atomic_t count; 172 173 /** Unique ID for the interrupt request */ 174 u64 intr_unique; 175 176 /* 177 * The following bitfields are either set once before the 178 * request is queued or setting/clearing them is protected by 179 * fuse_conn->lock 180 */ 181 182 /** True if the request has reply */ 183 unsigned isreply:1; 184 185 /** Force sending of the request even if interrupted */ 186 unsigned force:1; 187 188 /** The request was aborted */ 189 unsigned aborted:1; 190 191 /** Request is sent in the background */ 192 unsigned background:1; 193 194 /** The request has been interrupted */ 195 unsigned interrupted:1; 196 197 /** Data is being copied to/from the request */ 198 unsigned locked:1; 199 200 /** Request is counted as "waiting" */ 201 unsigned waiting:1; 202 203 /** State of the request */ 204 enum fuse_req_state state; 205 206 /** The request input */ 207 struct fuse_in in; 208 209 /** The request output */ 210 struct fuse_out out; 211 212 /** Used to wake up the task waiting for completion of request*/ 213 wait_queue_head_t waitq; 214 215 /** Data for asynchronous requests */ 216 union { 217 struct fuse_forget_in forget_in; 218 struct fuse_release_in release_in; 219 struct fuse_init_in init_in; 220 struct fuse_init_out init_out; 221 struct fuse_read_in read_in; 222 struct { 223 struct fuse_write_in in; 224 struct fuse_write_out out; 225 } write; 226 struct fuse_lk_in lk_in; 227 } misc; 228 229 /** page vector */ 230 struct page *pages[FUSE_MAX_PAGES_PER_REQ]; 231 232 /** number of pages in vector */ 233 unsigned num_pages; 234 235 /** offset of data on first page */ 236 unsigned page_offset; 237 238 /** File used in the request (or NULL) */ 239 struct fuse_file *ff; 240 241 /** vfsmount used in release */ 242 struct vfsmount *vfsmount; 243 244 /** dentry used in release */ 245 struct dentry *dentry; 246 247 /** Request completion callback */ 248 void (*end)(struct fuse_conn *, struct fuse_req *); 249 250 /** Request is stolen from fuse_file->reserved_req */ 251 struct file *stolen_file; 252 }; 253 254 /** 255 * A Fuse connection. 256 * 257 * This structure is created, when the filesystem is mounted, and is 258 * destroyed, when the client device is closed and the filesystem is 259 * unmounted. 260 */ 261 struct fuse_conn { 262 /** Lock protecting accessess to members of this structure */ 263 spinlock_t lock; 264 265 /** Mutex protecting against directory alias creation */ 266 struct mutex inst_mutex; 267 268 /** Refcount */ 269 atomic_t count; 270 271 /** The user id for this mount */ 272 uid_t user_id; 273 274 /** The group id for this mount */ 275 gid_t group_id; 276 277 /** The fuse mount flags for this mount */ 278 unsigned flags; 279 280 /** Maximum read size */ 281 unsigned max_read; 282 283 /** Maximum write size */ 284 unsigned max_write; 285 286 /** Readers of the connection are waiting on this */ 287 wait_queue_head_t waitq; 288 289 /** The list of pending requests */ 290 struct list_head pending; 291 292 /** The list of requests being processed */ 293 struct list_head processing; 294 295 /** The list of requests under I/O */ 296 struct list_head io; 297 298 /** Number of requests currently in the background */ 299 unsigned num_background; 300 301 /** Pending interrupts */ 302 struct list_head interrupts; 303 304 /** Flag indicating if connection is blocked. This will be 305 the case before the INIT reply is received, and if there 306 are too many outstading backgrounds requests */ 307 int blocked; 308 309 /** waitq for blocked connection */ 310 wait_queue_head_t blocked_waitq; 311 312 /** waitq for reserved requests */ 313 wait_queue_head_t reserved_req_waitq; 314 315 /** The next unique request id */ 316 u64 reqctr; 317 318 /** Connection established, cleared on umount, connection 319 abort and device release */ 320 unsigned connected; 321 322 /** Connection failed (version mismatch). Cannot race with 323 setting other bitfields since it is only set once in INIT 324 reply, before any other request, and never cleared */ 325 unsigned conn_error : 1; 326 327 /** Connection successful. Only set in INIT */ 328 unsigned conn_init : 1; 329 330 /** Do readpages asynchronously? Only set in INIT */ 331 unsigned async_read : 1; 332 333 /** Do not send separate SETATTR request before open(O_TRUNC) */ 334 unsigned atomic_o_trunc : 1; 335 336 /* 337 * The following bitfields are only for optimization purposes 338 * and hence races in setting them will not cause malfunction 339 */ 340 341 /** Is fsync not implemented by fs? */ 342 unsigned no_fsync : 1; 343 344 /** Is fsyncdir not implemented by fs? */ 345 unsigned no_fsyncdir : 1; 346 347 /** Is flush not implemented by fs? */ 348 unsigned no_flush : 1; 349 350 /** Is setxattr not implemented by fs? */ 351 unsigned no_setxattr : 1; 352 353 /** Is getxattr not implemented by fs? */ 354 unsigned no_getxattr : 1; 355 356 /** Is listxattr not implemented by fs? */ 357 unsigned no_listxattr : 1; 358 359 /** Is removexattr not implemented by fs? */ 360 unsigned no_removexattr : 1; 361 362 /** Are file locking primitives not implemented by fs? */ 363 unsigned no_lock : 1; 364 365 /** Is access not implemented by fs? */ 366 unsigned no_access : 1; 367 368 /** Is create not implemented by fs? */ 369 unsigned no_create : 1; 370 371 /** Is interrupt not implemented by fs? */ 372 unsigned no_interrupt : 1; 373 374 /** Is bmap not implemented by fs? */ 375 unsigned no_bmap : 1; 376 377 /** The number of requests waiting for completion */ 378 atomic_t num_waiting; 379 380 /** Negotiated minor version */ 381 unsigned minor; 382 383 /** Backing dev info */ 384 struct backing_dev_info bdi; 385 386 /** Entry on the fuse_conn_list */ 387 struct list_head entry; 388 389 /** Unique ID */ 390 u64 id; 391 392 /** Dentries in the control filesystem */ 393 struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES]; 394 395 /** number of dentries used in the above array */ 396 int ctl_ndents; 397 398 /** O_ASYNC requests */ 399 struct fasync_struct *fasync; 400 401 /** Key for lock owner ID scrambling */ 402 u32 scramble_key[4]; 403 404 /** Reserved request for the DESTROY message */ 405 struct fuse_req *destroy_req; 406 407 /** Version counter for attribute changes */ 408 u64 attr_version; 409 }; 410 411 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb) 412 { 413 return sb->s_fs_info; 414 } 415 416 static inline struct fuse_conn *get_fuse_conn(struct inode *inode) 417 { 418 return get_fuse_conn_super(inode->i_sb); 419 } 420 421 static inline struct fuse_inode *get_fuse_inode(struct inode *inode) 422 { 423 return container_of(inode, struct fuse_inode, inode); 424 } 425 426 static inline u64 get_node_id(struct inode *inode) 427 { 428 return get_fuse_inode(inode)->nodeid; 429 } 430 431 /** Device operations */ 432 extern const struct file_operations fuse_dev_operations; 433 434 /** 435 * Get a filled in inode 436 */ 437 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid, 438 int generation, struct fuse_attr *attr, 439 u64 attr_valid, u64 attr_version); 440 441 /** 442 * Send FORGET command 443 */ 444 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req, 445 unsigned long nodeid, u64 nlookup); 446 447 /** 448 * Initialize READ or READDIR request 449 */ 450 void fuse_read_fill(struct fuse_req *req, struct file *file, 451 struct inode *inode, loff_t pos, size_t count, int opcode); 452 453 /** 454 * Send OPEN or OPENDIR request 455 */ 456 int fuse_open_common(struct inode *inode, struct file *file, int isdir); 457 458 struct fuse_file *fuse_file_alloc(void); 459 void fuse_file_free(struct fuse_file *ff); 460 void fuse_finish_open(struct inode *inode, struct file *file, 461 struct fuse_file *ff, struct fuse_open_out *outarg); 462 463 /** Fill in ff->reserved_req with a RELEASE request */ 464 void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode); 465 466 /** 467 * Send RELEASE or RELEASEDIR request 468 */ 469 int fuse_release_common(struct inode *inode, struct file *file, int isdir); 470 471 /** 472 * Send FSYNC or FSYNCDIR request 473 */ 474 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync, 475 int isdir); 476 477 /** 478 * Initialize file operations on a regular file 479 */ 480 void fuse_init_file_inode(struct inode *inode); 481 482 /** 483 * Initialize inode operations on regular files and special files 484 */ 485 void fuse_init_common(struct inode *inode); 486 487 /** 488 * Initialize inode and file operations on a directory 489 */ 490 void fuse_init_dir(struct inode *inode); 491 492 /** 493 * Initialize inode operations on a symlink 494 */ 495 void fuse_init_symlink(struct inode *inode); 496 497 /** 498 * Change attributes of an inode 499 */ 500 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, 501 u64 attr_valid, u64 attr_version); 502 503 /** 504 * Initialize the client device 505 */ 506 int fuse_dev_init(void); 507 508 /** 509 * Cleanup the client device 510 */ 511 void fuse_dev_cleanup(void); 512 513 int fuse_ctl_init(void); 514 void fuse_ctl_cleanup(void); 515 516 /** 517 * Allocate a request 518 */ 519 struct fuse_req *fuse_request_alloc(void); 520 521 /** 522 * Free a request 523 */ 524 void fuse_request_free(struct fuse_req *req); 525 526 /** 527 * Get a request, may fail with -ENOMEM 528 */ 529 struct fuse_req *fuse_get_req(struct fuse_conn *fc); 530 531 /** 532 * Gets a requests for a file operation, always succeeds 533 */ 534 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file); 535 536 /** 537 * Decrement reference count of a request. If count goes to zero free 538 * the request. 539 */ 540 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req); 541 542 /** 543 * Send a request (synchronous) 544 */ 545 void request_send(struct fuse_conn *fc, struct fuse_req *req); 546 547 /** 548 * Send a request with no reply 549 */ 550 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req); 551 552 /** 553 * Send a request in the background 554 */ 555 void request_send_background(struct fuse_conn *fc, struct fuse_req *req); 556 557 /* Abort all requests */ 558 void fuse_abort_conn(struct fuse_conn *fc); 559 560 /** 561 * Invalidate inode attributes 562 */ 563 void fuse_invalidate_attr(struct inode *inode); 564 565 /** 566 * Acquire reference to fuse_conn 567 */ 568 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc); 569 570 /** 571 * Release reference to fuse_conn 572 */ 573 void fuse_conn_put(struct fuse_conn *fc); 574 575 /** 576 * Add connection to control filesystem 577 */ 578 int fuse_ctl_add_conn(struct fuse_conn *fc); 579 580 /** 581 * Remove connection from control filesystem 582 */ 583 void fuse_ctl_remove_conn(struct fuse_conn *fc); 584 585 /** 586 * Is file type valid? 587 */ 588 int fuse_valid_type(int m); 589 590 /** 591 * Is task allowed to perform filesystem operation? 592 */ 593 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task); 594 595 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id); 596 597 int fuse_update_attributes(struct inode *inode, struct kstat *stat, 598 struct file *file, bool *refreshed); 599