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 #ifndef _FS_FUSE_I_H
  10 #define _FS_FUSE_I_H
  11
  12 #include <linux/fuse.h>
  13 #include <linux/fs.h>
  14 #include <linux/mount.h>
  15 #include <linux/wait.h>
  16 #include <linux/list.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/mm.h>
  19 #include <linux/backing-dev.h>
  20 #include <linux/mutex.h>
  21 #include <linux/rwsem.h>
  22
  23 /** Max number of pages that can be used in a single read request */
  24 #define FUSE_MAX_PAGES_PER_REQ 32
  25
  26 /** Maximum number of outstanding background requests */
  27 #define FUSE_MAX_BACKGROUND 12
  28
  29 /** Congestion starts at 75% of maximum */
  30 #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100)
  31
  32 /** Bias for fi->writectr, meaning new writepages must not be sent */
  33 #define FUSE_NOWRITE INT_MIN
  34
  35 /** It could be as large as PATH_MAX, but would that have any uses? */
  36 #define FUSE_NAME_MAX 1024
  37
  38 /** Number of dentries for each connection in the control filesystem */
  39 #define FUSE_CTL_NUM_DENTRIES 3
  40
  41 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
  42     module will check permissions based on the file mode.  Otherwise no
  43     permission checking is done in the kernel */
  44 #define FUSE_DEFAULT_PERMISSIONS (1 << 0)
  45
  46 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user
  47     doing the mount will be allowed to access the filesystem */
  48 #define FUSE_ALLOW_OTHER         (1 << 1)
  49
  50 /** List of active connections */
  51 extern struct list_head fuse_conn_list;
  52
  53 /** Global mutex protecting fuse_conn_list and the control filesystem */
  54 extern struct mutex fuse_mutex;
  55
  56 /** FUSE inode */
  57 struct fuse_inode {
  58         /** Inode data */
  59         struct inode inode;
  60
  61         /** Unique ID, which identifies the inode between userspace
  62          * and kernel */
  63         u64 nodeid;
  64
  65         /** Number of lookups on this inode */
  66         u64 nlookup;
  67
  68         /** The request used for sending the FORGET message */
  69         struct fuse_req *forget_req;
  70
  71         /** Time in jiffies until the file attributes are valid */
  72         u64 i_time;
  73
  74         /** The sticky bit in inode->i_mode may have been removed, so
  75             preserve the original mode */
  76         mode_t orig_i_mode;
  77
  78         /** Version of last attribute change */
  79         u64 attr_version;
  80
  81         /** Files usable in writepage.  Protected by fc->lock */
  82         struct list_head write_files;
  83
  84         /** Writepages pending on truncate or fsync */
  85         struct list_head queued_writes;
  86
  87         /** Number of sent writes, a negative bias (FUSE_NOWRITE)
  88          * means more writes are blocked */
  89         int writectr;
  90
  91         /** Waitq for writepage completion */
  92         wait_queue_head_t page_waitq;
  93
  94         /** List of writepage requestst (pending or sent) */
  95         struct list_head writepages;
  96 };
  97
  98 /** FUSE specific file data */
  99 struct fuse_file {
 100         /** Request reserved for flush and release */
 101         struct fuse_req *reserved_req;
 102
 103         /** File handle used by userspace */
 104         u64 fh;
 105
 106         /** Refcount */
 107         atomic_t count;
 108
 109         /** Entry on inode's write_files list */
 110         struct list_head write_entry;
 111 };
 112
 113 /** One input argument of a request */
 114 struct fuse_in_arg {
 115         unsigned size;
 116         const void *value;
 117 };
 118
 119 /** The request input */
 120 struct fuse_in {
 121         /** The request header */
 122         struct fuse_in_header h;
 123
 124         /** True if the data for the last argument is in req->pages */
 125         unsigned argpages:1;
 126
 127         /** Number of arguments */
 128         unsigned numargs;
 129
 130         /** Array of arguments */
 131         struct fuse_in_arg args[3];
 132 };
 133
 134 /** One output argument of a request */
 135 struct fuse_arg {
 136         unsigned size;
 137         void *value;
 138 };
 139
 140 /** The request output */
 141 struct fuse_out {
 142         /** Header returned from userspace */
 143         struct fuse_out_header h;
 144
 145         /*
 146          * The following bitfields are not changed during the request
 147          * processing
 148          */
 149
 150         /** Last argument is variable length (can be shorter than
 151             arg->size) */
 152         unsigned argvar:1;
 153
 154         /** Last argument is a list of pages to copy data to */
 155         unsigned argpages:1;
 156
 157         /** Zero partially or not copied pages */
 158         unsigned page_zeroing:1;
 159
 160         /** Number or arguments */
 161         unsigned numargs;
 162
 163         /** Array of arguments */
 164         struct fuse_arg args[3];
 165 };
 166
 167 /** The request state */
 168 enum fuse_req_state {
 169         FUSE_REQ_INIT = 0,
 170         FUSE_REQ_PENDING,
 171         FUSE_REQ_READING,
 172         FUSE_REQ_SENT,
 173         FUSE_REQ_WRITING,
 174         FUSE_REQ_FINISHED
 175 };
 176
 177 struct fuse_conn;
 178
 179 /**
 180  * A request to the client
 181  */
 182 struct fuse_req {
 183         /** This can be on either pending processing or io lists in
 184             fuse_conn */
 185         struct list_head list;
 186
 187         /** Entry on the interrupts list  */
 188         struct list_head intr_entry;
 189
 190         /** refcount */
 191         atomic_t count;
 192
 193         /** Unique ID for the interrupt request */
 194         u64 intr_unique;
 195
 196         /*
 197          * The following bitfields are either set once before the
 198          * request is queued or setting/clearing them is protected by
 199          * fuse_conn->lock
 200          */
 201
 202         /** True if the request has reply */
 203         unsigned isreply:1;
 204
 205         /** Force sending of the request even if interrupted */
 206         unsigned force:1;
 207
 208         /** The request was aborted */
 209         unsigned aborted:1;
 210
 211         /** Request is sent in the background */
 212         unsigned background:1;
 213
 214         /** The request has been interrupted */
 215         unsigned interrupted:1;
 216
 217         /** Data is being copied to/from the request */
 218         unsigned locked:1;
 219
 220         /** Request is counted as "waiting" */
 221         unsigned waiting:1;
 222
 223         /** State of the request */
 224         enum fuse_req_state state;
 225
 226         /** The request input */
 227         struct fuse_in in;
 228
 229         /** The request output */
 230         struct fuse_out out;
 231
 232         /** Used to wake up the task waiting for completion of request*/
 233         wait_queue_head_t waitq;
 234
 235         /** Data for asynchronous requests */
 236         union {
 237                 struct fuse_forget_in forget_in;
 238                 struct {
 239                         struct fuse_release_in in;
 240                         struct vfsmount *vfsmount;
 241                         struct dentry *dentry;
 242                 } release;
 243                 struct fuse_init_in init_in;
 244                 struct fuse_init_out init_out;
 245                 struct {
 246                         struct fuse_read_in in;
 247                         u64 attr_ver;
 248                 } read;
 249                 struct {
 250                         struct fuse_write_in in;
 251                         struct fuse_write_out out;
 252                 } write;
 253                 struct fuse_lk_in lk_in;
 254         } misc;
 255
 256         /** page vector */
 257         struct page *pages[FUSE_MAX_PAGES_PER_REQ];
 258
 259         /** number of pages in vector */
 260         unsigned num_pages;
 261
 262         /** offset of data on first page */
 263         unsigned page_offset;
 264
 265         /** File used in the request (or NULL) */
 266         struct fuse_file *ff;
 267
 268         /** Inode used in the request or NULL */
 269         struct inode *inode;
 270
 271         /** Link on fi->writepages */
 272         struct list_head writepages_entry;
 273
 274         /** Request completion callback */
 275         void (*end)(struct fuse_conn *, struct fuse_req *);
 276
 277         /** Request is stolen from fuse_file->reserved_req */
 278         struct file *stolen_file;
 279 };
 280
 281 /**
 282  * A Fuse connection.
 283  *
 284  * This structure is created, when the filesystem is mounted, and is
 285  * destroyed, when the client device is closed and the filesystem is
 286  * unmounted.
 287  */
 288 struct fuse_conn {
 289         /** Lock protecting accessess to  members of this structure */
 290         spinlock_t lock;
 291
 292         /** Mutex protecting against directory alias creation */
 293         struct mutex inst_mutex;
 294
 295         /** Refcount */
 296         atomic_t count;
 297
 298         /** The user id for this mount */
 299         uid_t user_id;
 300
 301         /** The group id for this mount */
 302         gid_t group_id;
 303
 304         /** The fuse mount flags for this mount */
 305         unsigned flags;
 306
 307         /** Maximum read size */
 308         unsigned max_read;
 309
 310         /** Maximum write size */
 311         unsigned max_write;
 312
 313         /** Readers of the connection are waiting on this */
 314         wait_queue_head_t waitq;
 315
 316         /** The list of pending requests */
 317         struct list_head pending;
 318
 319         /** The list of requests being processed */
 320         struct list_head processing;
 321
 322         /** The list of requests under I/O */
 323         struct list_head io;
 324
 325         /** Number of requests currently in the background */
 326         unsigned num_background;
 327
 328         /** Number of background requests currently queued for userspace */
 329         unsigned active_background;
 330
 331         /** The list of background requests set aside for later queuing */
 332         struct list_head bg_queue;
 333
 334         /** Pending interrupts */
 335         struct list_head interrupts;
 336
 337         /** Flag indicating if connection is blocked.  This will be
 338             the case before the INIT reply is received, and if there
 339             are too many outstading backgrounds requests */
 340         int blocked;
 341
 342         /** waitq for blocked connection */
 343         wait_queue_head_t blocked_waitq;
 344
 345         /** waitq for reserved requests */
 346         wait_queue_head_t reserved_req_waitq;
 347
 348         /** The next unique request id */
 349         u64 reqctr;
 350
 351         /** Connection established, cleared on umount, connection
 352             abort and device release */
 353         unsigned connected;
 354
 355         /** Connection failed (version mismatch).  Cannot race with
 356             setting other bitfields since it is only set once in INIT
 357             reply, before any other request, and never cleared */
 358         unsigned conn_error : 1;
 359
 360         /** Connection successful.  Only set in INIT */
 361         unsigned conn_init : 1;
 362
 363         /** Do readpages asynchronously?  Only set in INIT */
 364         unsigned async_read : 1;
 365
 366         /** Do not send separate SETATTR request before open(O_TRUNC)  */
 367         unsigned atomic_o_trunc : 1;
 368
 369         /** Filesystem supports NFS exporting.  Only set in INIT */
 370         unsigned export_support : 1;
 371
 372         /*
 373          * The following bitfields are only for optimization purposes
 374          * and hence races in setting them will not cause malfunction
 375          */
 376
 377         /** Is fsync not implemented by fs? */
 378         unsigned no_fsync : 1;
 379
 380         /** Is fsyncdir not implemented by fs? */
 381         unsigned no_fsyncdir : 1;
 382
 383         /** Is flush not implemented by fs? */
 384         unsigned no_flush : 1;
 385
 386         /** Is setxattr not implemented by fs? */
 387         unsigned no_setxattr : 1;
 388
 389         /** Is getxattr not implemented by fs? */
 390         unsigned no_getxattr : 1;
 391
 392         /** Is listxattr not implemented by fs? */
 393         unsigned no_listxattr : 1;
 394
 395         /** Is removexattr not implemented by fs? */
 396         unsigned no_removexattr : 1;
 397
 398         /** Are file locking primitives not implemented by fs? */
 399         unsigned no_lock : 1;
 400
 401         /** Is access not implemented by fs? */
 402         unsigned no_access : 1;
 403
 404         /** Is create not implemented by fs? */
 405         unsigned no_create : 1;
 406
 407         /** Is interrupt not implemented by fs? */
 408         unsigned no_interrupt : 1;
 409
 410         /** Is bmap not implemented by fs? */
 411         unsigned no_bmap : 1;
 412
 413         /** Do multi-page cached writes */
 414         unsigned big_writes : 1;
 415
 416         /** The number of requests waiting for completion */
 417         atomic_t num_waiting;
 418
 419         /** Negotiated minor version */
 420         unsigned minor;
 421
 422         /** Backing dev info */
 423         struct backing_dev_info bdi;
 424
 425         /** Entry on the fuse_conn_list */
 426         struct list_head entry;
 427
 428         /** Device ID from super block */
 429         dev_t dev;
 430
 431         /** Dentries in the control filesystem */
 432         struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
 433
 434         /** number of dentries used in the above array */
 435         int ctl_ndents;
 436
 437         /** O_ASYNC requests */
 438         struct fasync_struct *fasync;
 439
 440         /** Key for lock owner ID scrambling */
 441         u32 scramble_key[4];
 442
 443         /** Reserved request for the DESTROY message */
 444         struct fuse_req *destroy_req;
 445
 446         /** Version counter for attribute changes */
 447         u64 attr_version;
 448 };
 449
 450 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 451 {
 452         return sb->s_fs_info;
 453 }
 454
 455 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 456 {
 457         return get_fuse_conn_super(inode->i_sb);
 458 }
 459
 460 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 461 {
 462         return container_of(inode, struct fuse_inode, inode);
 463 }
 464
 465 static inline u64 get_node_id(struct inode *inode)
 466 {
 467         return get_fuse_inode(inode)->nodeid;
 468 }
 469
 470 /** Device operations */
 471 extern const struct file_operations fuse_dev_operations;
 472
 473 extern struct dentry_operations fuse_dentry_operations;
 474
 475 /**
 476  * Get a filled in inode
 477  */
 478 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 479                         int generation, struct fuse_attr *attr,
 480                         u64 attr_valid, u64 attr_version);
 481
 482 int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
 483                      struct fuse_entry_out *outarg, struct inode **inode);
 484
 485 /**
 486  * Send FORGET command
 487  */
 488 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 489                       u64 nodeid, u64 nlookup);
 490
 491 /**
 492  * Initialize READ or READDIR request
 493  */
 494 void fuse_read_fill(struct fuse_req *req, struct file *file,
 495                     struct inode *inode, loff_t pos, size_t count, int opcode);
 496
 497 /**
 498  * Send OPEN or OPENDIR request
 499  */
 500 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
 501
 502 struct fuse_file *fuse_file_alloc(void);
 503 void fuse_file_free(struct fuse_file *ff);
 504 void fuse_finish_open(struct inode *inode, struct file *file,
 505                       struct fuse_file *ff, struct fuse_open_out *outarg);
 506
 507 /** Fill in ff->reserved_req with a RELEASE request */
 508 void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode);
 509
 510 /**
 511  * Send RELEASE or RELEASEDIR request
 512  */
 513 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
 514
 515 /**
 516  * Send FSYNC or FSYNCDIR request
 517  */
 518 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 519                       int isdir);
 520
 521 /**
 522  * Initialize file operations on a regular file
 523  */
 524 void fuse_init_file_inode(struct inode *inode);
 525
 526 /**
 527  * Initialize inode operations on regular files and special files
 528  */
 529 void fuse_init_common(struct inode *inode);
 530
 531 /**
 532  * Initialize inode and file operations on a directory
 533  */
 534 void fuse_init_dir(struct inode *inode);
 535
 536 /**
 537  * Initialize inode operations on a symlink
 538  */
 539 void fuse_init_symlink(struct inode *inode);
 540
 541 /**
 542  * Change attributes of an inode
 543  */
 544 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
 545                             u64 attr_valid, u64 attr_version);
 546
 547 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 548                                    u64 attr_valid);
 549
 550 void fuse_truncate(struct address_space *mapping, loff_t offset);
 551
 552 /**
 553  * Initialize the client device
 554  */
 555 int fuse_dev_init(void);
 556
 557 /**
 558  * Cleanup the client device
 559  */
 560 void fuse_dev_cleanup(void);
 561
 562 int fuse_ctl_init(void);
 563 void fuse_ctl_cleanup(void);
 564
 565 /**
 566  * Allocate a request
 567  */
 568 struct fuse_req *fuse_request_alloc(void);
 569
 570 struct fuse_req *fuse_request_alloc_nofs(void);
 571
 572 /**
 573  * Free a request
 574  */
 575 void fuse_request_free(struct fuse_req *req);
 576
 577 /**
 578  * Get a request, may fail with -ENOMEM
 579  */
 580 struct fuse_req *fuse_get_req(struct fuse_conn *fc);
 581
 582 /**
 583  * Gets a requests for a file operation, always succeeds
 584  */
 585 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
 586
 587 /**
 588  * Decrement reference count of a request.  If count goes to zero free
 589  * the request.
 590  */
 591 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
 592
 593 /**
 594  * Send a request (synchronous)
 595  */
 596 void request_send(struct fuse_conn *fc, struct fuse_req *req);
 597
 598 /**
 599  * Send a request with no reply
 600  */
 601 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
 602
 603 /**
 604  * Send a request in the background
 605  */
 606 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 607
 608 void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req);
 609
 610 /* Abort all requests */
 611 void fuse_abort_conn(struct fuse_conn *fc);
 612
 613 /**
 614  * Invalidate inode attributes
 615  */
 616 void fuse_invalidate_attr(struct inode *inode);
 617
 618 void fuse_invalidate_entry_cache(struct dentry *entry);
 619
 620 /**
 621  * Acquire reference to fuse_conn
 622  */
 623 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
 624
 625 /**
 626  * Release reference to fuse_conn
 627  */
 628 void fuse_conn_put(struct fuse_conn *fc);
 629
 630 /**
 631  * Add connection to control filesystem
 632  */
 633 int fuse_ctl_add_conn(struct fuse_conn *fc);
 634
 635 /**
 636  * Remove connection from control filesystem
 637  */
 638 void fuse_ctl_remove_conn(struct fuse_conn *fc);
 639
 640 /**
 641  * Is file type valid?
 642  */
 643 int fuse_valid_type(int m);
 644
 645 /**
 646  * Is task allowed to perform filesystem operation?
 647  */
 648 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
 649
 650 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
 651
 652 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
 653                            struct file *file, bool *refreshed);
 654
 655 void fuse_flush_writepages(struct inode *inode);
 656
 657 void fuse_set_nowrite(struct inode *inode);
 658 void fuse_release_nowrite(struct inode *inode);
 659
 660 u64 fuse_get_attr_version(struct fuse_conn *fc);
 661
 662 #endif /* _FS_FUSE_I_H */