fs/fuse/fuse_i.h

   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);