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 #include <linux/rwsem.h> 19 20 /** Max number of pages that can be used in a single read request */ 21 #define FUSE_MAX_PAGES_PER_REQ 32 22 23 /** Maximum number of outstanding background requests */ 24 #define FUSE_MAX_BACKGROUND 12 25 26 /** Congestion starts at 75% of maximum */ 27 #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100) 28 29 /** Bias for fi->writectr, meaning new writepages must not be sent */ 30 #define FUSE_NOWRITE INT_MIN 31 32 /** It could be as large as PATH_MAX, but would that have any uses? */ 33 #define FUSE_NAME_MAX 1024 34 35 /** Number of dentries for each connection in the control filesystem */ 36 #define FUSE_CTL_NUM_DENTRIES 3 37 38 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem 39 module will check permissions based on the file mode. Otherwise no 40 permission checking is done in the kernel */ 41 #define FUSE_DEFAULT_PERMISSIONS (1 << 0) 42 43 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user 44 doing the mount will be allowed to access the filesystem */ 45 #define FUSE_ALLOW_OTHER (1 << 1) 46 47 /** List of active connections */ 48 extern struct list_head fuse_conn_list; 49 50 /** Global mutex protecting fuse_conn_list and the control filesystem */ 51 extern struct mutex fuse_mutex; 52 53 /** FUSE inode */ 54 struct fuse_inode { 55 /** Inode data */ 56 struct inode inode; 57 58 /** Unique ID, which identifies the inode between userspace 59 * and kernel */ 60 u64 nodeid; 61 62 /** Number of lookups on this inode */ 63 u64 nlookup; 64 65 /** The request used for sending the FORGET message */ 66 struct fuse_req *forget_req; 67 68 /** Time in jiffies until the file attributes are valid */ 69 u64 i_time; 70 71 /** The sticky bit in inode->i_mode may have been removed, so 72 preserve the original mode */ 73 mode_t orig_i_mode; 74 75 /** Version of last attribute change */ 76 u64 attr_version; 77 78 /** Files usable in writepage. Protected by fc->lock */ 79 struct list_head write_files; 80 81 /** Writepages pending on truncate or fsync */ 82 struct list_head queued_writes; 83 84 /** Number of sent writes, a negative bias (FUSE_NOWRITE) 85 * means more writes are blocked */ 86 int writectr; 87 88 /** Waitq for writepage completion */ 89 wait_queue_head_t page_waitq; 90 91 /** List of writepage requestst (pending or sent) */ 92 struct list_head writepages; 93 }; 94 95 /** FUSE specific file data */ 96 struct fuse_file { 97 /** Request reserved for flush and release */ 98 struct fuse_req *reserved_req; 99 100 /** File handle used by userspace */ 101 u64 fh; 102 103 /** Refcount */ 104 atomic_t count; 105 106 /** Entry on inode's write_files list */ 107 struct list_head write_entry; 108 }; 109 110 /** One input argument of a request */ 111 struct fuse_in_arg { 112 unsigned size; 113 const void *value; 114 }; 115 116 /** The request input */ 117 struct fuse_in { 118 /** The request header */ 119 struct fuse_in_header h; 120 121 /** True if the data for the last argument is in req->pages */ 122 unsigned argpages:1; 123 124 /** Number of arguments */ 125 unsigned numargs; 126 127 /** Array of arguments */ 128 struct fuse_in_arg args[3]; 129 }; 130 131 /** One output argument of a request */ 132 struct fuse_arg { 133 unsigned size; 134 void *value; 135 }; 136 137 /** The request output */ 138 struct fuse_out { 139 /** Header returned from userspace */ 140 struct fuse_out_header h; 141 142 /* 143 * The following bitfields are not changed during the request 144 * processing 145 */ 146 147 /** Last argument is variable length (can be shorter than 148 arg->size) */ 149 unsigned argvar:1; 150 151 /** Last argument is a list of pages to copy data to */ 152 unsigned argpages:1; 153 154 /** Zero partially or not copied pages */ 155 unsigned page_zeroing:1; 156 157 /** Number or arguments */ 158 unsigned numargs; 159 160 /** Array of arguments */ 161 struct fuse_arg args[3]; 162 }; 163 164 /** The request state */ 165 enum fuse_req_state { 166 FUSE_REQ_INIT = 0, 167 FUSE_REQ_PENDING, 168 FUSE_REQ_READING, 169 FUSE_REQ_SENT, 170 FUSE_REQ_WRITING, 171 FUSE_REQ_FINISHED 172 }; 173 174 struct fuse_conn; 175 176 /** 177 * A request to the client 178 */ 179 struct fuse_req { 180 /** This can be on either pending processing or io lists in 181 fuse_conn */ 182 struct list_head list; 183 184 /** Entry on the interrupts list */ 185 struct list_head intr_entry; 186 187 /** refcount */ 188 atomic_t count; 189 190 /** Unique ID for the interrupt request */ 191 u64 intr_unique; 192 193 /* 194 * The following bitfields are either set once before the 195 * request is queued or setting/clearing them is protected by 196 * fuse_conn->lock 197 */ 198 199 /** True if the request has reply */ 200 unsigned isreply:1; 201 202 /** Force sending of the request even if interrupted */ 203 unsigned force:1; 204 205 /** The request was aborted */ 206 unsigned aborted:1; 207 208 /** Request is sent in the background */ 209 unsigned background:1; 210 211 /** The request has been interrupted */ 212 unsigned interrupted:1; 213 214 /** Data is being copied to/from the request */ 215 unsigned locked:1; 216 217 /** Request is counted as "waiting" */ 218 unsigned waiting:1; 219 220 /** State of the request */ 221 enum fuse_req_state state; 222 223 /** The request input */ 224 struct fuse_in in; 225 226 /** The request output */ 227 struct fuse_out out; 228 229 /** Used to wake up the task waiting for completion of request*/ 230 wait_queue_head_t waitq; 231 232 /** Data for asynchronous requests */ 233 union { 234 struct fuse_forget_in forget_in; 235 struct { 236 struct fuse_release_in in; 237 struct vfsmount *vfsmount; 238 struct dentry *dentry; 239 } release; 240 struct fuse_init_in init_in; 241 struct fuse_init_out init_out; 242 struct { 243 struct fuse_read_in in; 244 u64 attr_ver; 245 } read; 246 struct { 247 struct fuse_write_in in; 248 struct fuse_write_out out; 249 } write; 250 struct fuse_lk_in lk_in; 251 } misc; 252 253 /** page vector */ 254 struct page *pages[FUSE_MAX_PAGES_PER_REQ]; 255 256 /** number of pages in vector */ 257 unsigned num_pages; 258 259 /** offset of data on first page */ 260 unsigned page_offset; 261 262 /** File used in the request (or NULL) */ 263 struct fuse_file *ff; 264 265 /** Inode used in the request or NULL */ 266 struct inode *inode; 267 268 /** Link on fi->writepages */ 269 struct list_head writepages_entry; 270 271 /** Request completion callback */ 272 void (*end)(struct fuse_conn *, struct fuse_req *); 273 274 /** Request is stolen from fuse_file->reserved_req */ 275 struct file *stolen_file; 276 }; 277 278 /** 279 * A Fuse connection. 280 * 281 * This structure is created, when the filesystem is mounted, and is 282 * destroyed, when the client device is closed and the filesystem is 283 * unmounted. 284 */ 285 struct fuse_conn { 286 /** Lock protecting accessess to members of this structure */ 287 spinlock_t lock; 288 289 /** Mutex protecting against directory alias creation */ 290 struct mutex inst_mutex; 291 292 /** Refcount */ 293 atomic_t count; 294 295 /** The user id for this mount */ 296 uid_t user_id; 297 298 /** The group id for this mount */ 299 gid_t group_id; 300 301 /** The fuse mount flags for this mount */ 302 unsigned flags; 303 304 /** Maximum read size */ 305 unsigned max_read; 306 307 /** Maximum write size */ 308 unsigned max_write; 309 310 /** Readers of the connection are waiting on this */ 311 wait_queue_head_t waitq; 312 313 /** The list of pending requests */ 314 struct list_head pending; 315 316 /** The list of requests being processed */ 317 struct list_head processing; 318 319 /** The list of requests under I/O */ 320 struct list_head io; 321 322 /** Number of requests currently in the background */ 323 unsigned num_background; 324 325 /** Number of background requests currently queued for userspace */ 326 unsigned active_background; 327 328 /** The list of background requests set aside for later queuing */ 329 struct list_head bg_queue; 330 331 /** Pending interrupts */ 332 struct list_head interrupts; 333 334 /** Flag indicating if connection is blocked. This will be 335 the case before the INIT reply is received, and if there 336 are too many outstading backgrounds requests */ 337 int blocked; 338 339 /** waitq for blocked connection */ 340 wait_queue_head_t blocked_waitq; 341 342 /** waitq for reserved requests */ 343 wait_queue_head_t reserved_req_waitq; 344 345 /** The next unique request id */ 346 u64 reqctr; 347 348 /** Connection established, cleared on umount, connection 349 abort and device release */ 350 unsigned connected; 351 352 /** Connection failed (version mismatch). Cannot race with 353 setting other bitfields since it is only set once in INIT 354 reply, before any other request, and never cleared */ 355 unsigned conn_error : 1; 356 357 /** Connection successful. Only set in INIT */ 358 unsigned conn_init : 1; 359 360 /** Do readpages asynchronously? Only set in INIT */ 361 unsigned async_read : 1; 362 363 /** Do not send separate SETATTR request before open(O_TRUNC) */ 364 unsigned atomic_o_trunc : 1; 365 366 /* 367 * The following bitfields are only for optimization purposes 368 * and hence races in setting them will not cause malfunction 369 */ 370 371 /** Is fsync not implemented by fs? */ 372 unsigned no_fsync : 1; 373 374 /** Is fsyncdir not implemented by fs? */ 375 unsigned no_fsyncdir : 1; 376 377 /** Is flush not implemented by fs? */ 378 unsigned no_flush : 1; 379 380 /** Is setxattr not implemented by fs? */ 381 unsigned no_setxattr : 1; 382 383 /** Is getxattr not implemented by fs? */ 384 unsigned no_getxattr : 1; 385 386 /** Is listxattr not implemented by fs? */ 387 unsigned no_listxattr : 1; 388 389 /** Is removexattr not implemented by fs? */ 390 unsigned no_removexattr : 1; 391 392 /** Are file locking primitives not implemented by fs? */ 393 unsigned no_lock : 1; 394 395 /** Is access not implemented by fs? */ 396 unsigned no_access : 1; 397 398 /** Is create not implemented by fs? */ 399 unsigned no_create : 1; 400 401 /** Is interrupt not implemented by fs? */ 402 unsigned no_interrupt : 1; 403 404 /** Is bmap not implemented by fs? */ 405 unsigned no_bmap : 1; 406 407 /** Do multi-page cached writes */ 408 unsigned big_writes : 1; 409 410 /** The number of requests waiting for completion */ 411 atomic_t num_waiting; 412 413 /** Negotiated minor version */ 414 unsigned minor; 415 416 /** Backing dev info */ 417 struct backing_dev_info bdi; 418 419 /** Entry on the fuse_conn_list */ 420 struct list_head entry; 421 422 /** Device ID from super block */ 423 dev_t dev; 424 425 /** Dentries in the control filesystem */ 426 struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES]; 427 428 /** number of dentries used in the above array */ 429 int ctl_ndents; 430 431 /** O_ASYNC requests */ 432 struct fasync_struct *fasync; 433 434 /** Key for lock owner ID scrambling */ 435 u32 scramble_key[4]; 436 437 /** Reserved request for the DESTROY message */ 438 struct fuse_req *destroy_req; 439 440 /** Version counter for attribute changes */ 441 u64 attr_version; 442 }; 443 444 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb) 445 { 446 return sb->s_fs_info; 447 } 448 449 static inline struct fuse_conn *get_fuse_conn(struct inode *inode) 450 { 451 return get_fuse_conn_super(inode->i_sb); 452 } 453 454 static inline struct fuse_inode *get_fuse_inode(struct inode *inode) 455 { 456 return container_of(inode, struct fuse_inode, inode); 457 } 458 459 static inline u64 get_node_id(struct inode *inode) 460 { 461 return get_fuse_inode(inode)->nodeid; 462 } 463 464 /** Device operations */ 465 extern const struct file_operations fuse_dev_operations; 466 467 /** 468 * Get a filled in inode 469 */ 470 struct inode *fuse_iget(struct super_block *sb, u64 nodeid, 471 int generation, struct fuse_attr *attr, 472 u64 attr_valid, u64 attr_version); 473 474 /** 475 * Send FORGET command 476 */ 477 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req, 478 u64 nodeid, u64 nlookup); 479 480 /** 481 * Initialize READ or READDIR request 482 */ 483 void fuse_read_fill(struct fuse_req *req, struct file *file, 484 struct inode *inode, loff_t pos, size_t count, int opcode); 485 486 /** 487 * Send OPEN or OPENDIR request 488 */ 489 int fuse_open_common(struct inode *inode, struct file *file, int isdir); 490 491 struct fuse_file *fuse_file_alloc(void); 492 void fuse_file_free(struct fuse_file *ff); 493 void fuse_finish_open(struct inode *inode, struct file *file, 494 struct fuse_file *ff, struct fuse_open_out *outarg); 495 496 /** Fill in ff->reserved_req with a RELEASE request */ 497 void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode); 498 499 /** 500 * Send RELEASE or RELEASEDIR request 501 */ 502 int fuse_release_common(struct inode *inode, struct file *file, int isdir); 503 504 /** 505 * Send FSYNC or FSYNCDIR request 506 */ 507 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync, 508 int isdir); 509 510 /** 511 * Initialize file operations on a regular file 512 */ 513 void fuse_init_file_inode(struct inode *inode); 514 515 /** 516 * Initialize inode operations on regular files and special files 517 */ 518 void fuse_init_common(struct inode *inode); 519 520 /** 521 * Initialize inode and file operations on a directory 522 */ 523 void fuse_init_dir(struct inode *inode); 524 525 /** 526 * Initialize inode operations on a symlink 527 */ 528 void fuse_init_symlink(struct inode *inode); 529 530 /** 531 * Change attributes of an inode 532 */ 533 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, 534 u64 attr_valid, u64 attr_version); 535 536 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr, 537 u64 attr_valid); 538 539 void fuse_truncate(struct address_space *mapping, loff_t offset); 540 541 /** 542 * Initialize the client device 543 */ 544 int fuse_dev_init(void); 545 546 /** 547 * Cleanup the client device 548 */ 549 void fuse_dev_cleanup(void); 550 551 int fuse_ctl_init(void); 552 void fuse_ctl_cleanup(void); 553 554 /** 555 * Allocate a request 556 */ 557 struct fuse_req *fuse_request_alloc(void); 558 559 struct fuse_req *fuse_request_alloc_nofs(void); 560 561 /** 562 * Free a request 563 */ 564 void fuse_request_free(struct fuse_req *req); 565 566 /** 567 * Get a request, may fail with -ENOMEM 568 */ 569 struct fuse_req *fuse_get_req(struct fuse_conn *fc); 570 571 /** 572 * Gets a requests for a file operation, always succeeds 573 */ 574 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file); 575 576 /** 577 * Decrement reference count of a request. If count goes to zero free 578 * the request. 579 */ 580 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req); 581 582 /** 583 * Send a request (synchronous) 584 */ 585 void request_send(struct fuse_conn *fc, struct fuse_req *req); 586 587 /** 588 * Send a request with no reply 589 */ 590 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req); 591 592 /** 593 * Send a request in the background 594 */ 595 void request_send_background(struct fuse_conn *fc, struct fuse_req *req); 596 597 void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req); 598 599 /* Abort all requests */ 600 void fuse_abort_conn(struct fuse_conn *fc); 601 602 /** 603 * Invalidate inode attributes 604 */ 605 void fuse_invalidate_attr(struct inode *inode); 606 607 /** 608 * Acquire reference to fuse_conn 609 */ 610 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc); 611 612 /** 613 * Release reference to fuse_conn 614 */ 615 void fuse_conn_put(struct fuse_conn *fc); 616 617 /** 618 * Add connection to control filesystem 619 */ 620 int fuse_ctl_add_conn(struct fuse_conn *fc); 621 622 /** 623 * Remove connection from control filesystem 624 */ 625 void fuse_ctl_remove_conn(struct fuse_conn *fc); 626 627 /** 628 * Is file type valid? 629 */ 630 int fuse_valid_type(int m); 631 632 /** 633 * Is task allowed to perform filesystem operation? 634 */ 635 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task); 636 637 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id); 638 639 int fuse_update_attributes(struct inode *inode, struct kstat *stat, 640 struct file *file, bool *refreshed); 641 642 void fuse_flush_writepages(struct inode *inode); 643 644 void fuse_set_nowrite(struct inode *inode); 645 void fuse_release_nowrite(struct inode *inode); 646 647 u64 fuse_get_attr_version(struct fuse_conn *fc); 648