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
  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 {
 219                         struct fuse_release_in in;
 220                         struct vfsmount *vfsmount;
 221                         struct dentry *dentry;
 222                 } release;
 223                 struct fuse_init_in init_in;
 224                 struct fuse_init_out init_out;
 225                 struct fuse_read_in read_in;
 226                 struct {
 227                         struct fuse_write_in in;
 228                         struct fuse_write_out out;
 229                 } write;
 230                 struct fuse_lk_in lk_in;
 231         } misc;
 232
 233         /** page vector */
 234         struct page *pages[FUSE_MAX_PAGES_PER_REQ];
 235
 236         /** number of pages in vector */
 237         unsigned num_pages;
 238
 239         /** offset of data on first page */
 240         unsigned page_offset;
 241
 242         /** File used in the request (or NULL) */
 243         struct fuse_file *ff;
 244
 245         /** Request completion callback */
 246         void (*end)(struct fuse_conn *, struct fuse_req *);
 247
 248         /** Request is stolen from fuse_file->reserved_req */
 249         struct file *stolen_file;
 250 };
 251
 252 /**
 253  * A Fuse connection.
 254  *
 255  * This structure is created, when the filesystem is mounted, and is
 256  * destroyed, when the client device is closed and the filesystem is
 257  * unmounted.
 258  */
 259 struct fuse_conn {
 260         /** Lock protecting accessess to  members of this structure */
 261         spinlock_t lock;
 262
 263         /** Mutex protecting against directory alias creation */
 264         struct mutex inst_mutex;
 265
 266         /** Refcount */
 267         atomic_t count;
 268
 269         /** The user id for this mount */
 270         uid_t user_id;
 271
 272         /** The group id for this mount */
 273         gid_t group_id;
 274
 275         /** The fuse mount flags for this mount */
 276         unsigned flags;
 277
 278         /** Maximum read size */
 279         unsigned max_read;
 280
 281         /** Maximum write size */
 282         unsigned max_write;
 283
 284         /** Readers of the connection are waiting on this */
 285         wait_queue_head_t waitq;
 286
 287         /** The list of pending requests */
 288         struct list_head pending;
 289
 290         /** The list of requests being processed */
 291         struct list_head processing;
 292
 293         /** The list of requests under I/O */
 294         struct list_head io;
 295
 296         /** Number of requests currently in the background */
 297         unsigned num_background;
 298
 299         /** Number of background requests currently queued for userspace */
 300         unsigned active_background;
 301
 302         /** The list of background requests set aside for later queuing */
 303         struct list_head bg_queue;
 304
 305         /** Pending interrupts */
 306         struct list_head interrupts;
 307
 308         /** Flag indicating if connection is blocked.  This will be
 309             the case before the INIT reply is received, and if there
 310             are too many outstading backgrounds requests */
 311         int blocked;
 312
 313         /** waitq for blocked connection */
 314         wait_queue_head_t blocked_waitq;
 315
 316         /** waitq for reserved requests */
 317         wait_queue_head_t reserved_req_waitq;
 318
 319         /** The next unique request id */
 320         u64 reqctr;
 321
 322         /** Connection established, cleared on umount, connection
 323             abort and device release */
 324         unsigned connected;
 325
 326         /** Connection failed (version mismatch).  Cannot race with
 327             setting other bitfields since it is only set once in INIT
 328             reply, before any other request, and never cleared */
 329         unsigned conn_error : 1;
 330
 331         /** Connection successful.  Only set in INIT */
 332         unsigned conn_init : 1;
 333
 334         /** Do readpages asynchronously?  Only set in INIT */
 335         unsigned async_read : 1;
 336
 337         /** Do not send separate SETATTR request before open(O_TRUNC)  */
 338         unsigned atomic_o_trunc : 1;
 339
 340         /*
 341          * The following bitfields are only for optimization purposes
 342          * and hence races in setting them will not cause malfunction
 343          */
 344
 345         /** Is fsync not implemented by fs? */
 346         unsigned no_fsync : 1;
 347
 348         /** Is fsyncdir not implemented by fs? */
 349         unsigned no_fsyncdir : 1;
 350
 351         /** Is flush not implemented by fs? */
 352         unsigned no_flush : 1;
 353
 354         /** Is setxattr not implemented by fs? */
 355         unsigned no_setxattr : 1;
 356
 357         /** Is getxattr not implemented by fs? */
 358         unsigned no_getxattr : 1;
 359
 360         /** Is listxattr not implemented by fs? */
 361         unsigned no_listxattr : 1;
 362
 363         /** Is removexattr not implemented by fs? */
 364         unsigned no_removexattr : 1;
 365
 366         /** Are file locking primitives not implemented by fs? */
 367         unsigned no_lock : 1;
 368
 369         /** Is access not implemented by fs? */
 370         unsigned no_access : 1;
 371
 372         /** Is create not implemented by fs? */
 373         unsigned no_create : 1;
 374
 375         /** Is interrupt not implemented by fs? */
 376         unsigned no_interrupt : 1;
 377
 378         /** Is bmap not implemented by fs? */
 379         unsigned no_bmap : 1;
 380
 381         /** The number of requests waiting for completion */
 382         atomic_t num_waiting;
 383
 384         /** Negotiated minor version */
 385         unsigned minor;
 386
 387         /** Backing dev info */
 388         struct backing_dev_info bdi;
 389
 390         /** Entry on the fuse_conn_list */
 391         struct list_head entry;
 392
 393         /** Unique ID */
 394         u64 id;
 395
 396         /** Dentries in the control filesystem */
 397         struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
 398
 399         /** number of dentries used in the above array */
 400         int ctl_ndents;
 401
 402         /** O_ASYNC requests */
 403         struct fasync_struct *fasync;
 404
 405         /** Key for lock owner ID scrambling */
 406         u32 scramble_key[4];
 407
 408         /** Reserved request for the DESTROY message */
 409         struct fuse_req *destroy_req;
 410
 411         /** Version counter for attribute changes */
 412         u64 attr_version;
 413 };
 414
 415 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 416 {
 417         return sb->s_fs_info;
 418 }
 419
 420 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 421 {
 422         return get_fuse_conn_super(inode->i_sb);
 423 }
 424
 425 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 426 {
 427         return container_of(inode, struct fuse_inode, inode);
 428 }
 429
 430 static inline u64 get_node_id(struct inode *inode)
 431 {
 432         return get_fuse_inode(inode)->nodeid;
 433 }
 434
 435 /** Device operations */
 436 extern const struct file_operations fuse_dev_operations;
 437
 438 /**
 439  * Get a filled in inode
 440  */
 441 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 442                         int generation, struct fuse_attr *attr,
 443                         u64 attr_valid, u64 attr_version);
 444
 445 /**
 446  * Send FORGET command
 447  */
 448 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 449                       unsigned long nodeid, u64 nlookup);
 450
 451 /**
 452  * Initialize READ or READDIR request
 453  */
 454 void fuse_read_fill(struct fuse_req *req, struct file *file,
 455                     struct inode *inode, loff_t pos, size_t count, int opcode);
 456
 457 /**
 458  * Send OPEN or OPENDIR request
 459  */
 460 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
 461
 462 struct fuse_file *fuse_file_alloc(void);
 463 void fuse_file_free(struct fuse_file *ff);
 464 void fuse_finish_open(struct inode *inode, struct file *file,
 465                       struct fuse_file *ff, struct fuse_open_out *outarg);
 466
 467 /** Fill in ff->reserved_req with a RELEASE request */
 468 void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode);
 469
 470 /**
 471  * Send RELEASE or RELEASEDIR request
 472  */
 473 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
 474
 475 /**
 476  * Send FSYNC or FSYNCDIR request
 477  */
 478 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 479                       int isdir);
 480
 481 /**
 482  * Initialize file operations on a regular file
 483  */
 484 void fuse_init_file_inode(struct inode *inode);
 485
 486 /**
 487  * Initialize inode operations on regular files and special files
 488  */
 489 void fuse_init_common(struct inode *inode);
 490
 491 /**
 492  * Initialize inode and file operations on a directory
 493  */
 494 void fuse_init_dir(struct inode *inode);
 495
 496 /**
 497  * Initialize inode operations on a symlink
 498  */
 499 void fuse_init_symlink(struct inode *inode);
 500
 501 /**
 502  * Change attributes of an inode
 503  */
 504 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
 505                             u64 attr_valid, u64 attr_version);
 506
 507 /**
 508  * Initialize the client device
 509  */
 510 int fuse_dev_init(void);
 511
 512 /**
 513  * Cleanup the client device
 514  */
 515 void fuse_dev_cleanup(void);
 516
 517 int fuse_ctl_init(void);
 518 void fuse_ctl_cleanup(void);
 519
 520 /**
 521  * Allocate a request
 522  */
 523 struct fuse_req *fuse_request_alloc(void);
 524
 525 /**
 526  * Free a request
 527  */
 528 void fuse_request_free(struct fuse_req *req);
 529
 530 /**
 531  * Get a request, may fail with -ENOMEM
 532  */
 533 struct fuse_req *fuse_get_req(struct fuse_conn *fc);
 534
 535 /**
 536  * Gets a requests for a file operation, always succeeds
 537  */
 538 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
 539
 540 /**
 541  * Decrement reference count of a request.  If count goes to zero free
 542  * the request.
 543  */
 544 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
 545
 546 /**
 547  * Send a request (synchronous)
 548  */
 549 void request_send(struct fuse_conn *fc, struct fuse_req *req);
 550
 551 /**
 552  * Send a request with no reply
 553  */
 554 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
 555
 556 /**
 557  * Send a request in the background
 558  */
 559 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 560
 561 /* Abort all requests */
 562 void fuse_abort_conn(struct fuse_conn *fc);
 563
 564 /**
 565  * Invalidate inode attributes
 566  */
 567 void fuse_invalidate_attr(struct inode *inode);
 568
 569 /**
 570  * Acquire reference to fuse_conn
 571  */
 572 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
 573
 574 /**
 575  * Release reference to fuse_conn
 576  */
 577 void fuse_conn_put(struct fuse_conn *fc);
 578
 579 /**
 580  * Add connection to control filesystem
 581  */
 582 int fuse_ctl_add_conn(struct fuse_conn *fc);
 583
 584 /**
 585  * Remove connection from control filesystem
 586  */
 587 void fuse_ctl_remove_conn(struct fuse_conn *fc);
 588
 589 /**
 590  * Is file type valid?
 591  */
 592 int fuse_valid_type(int m);
 593
 594 /**
 595  * Is task allowed to perform filesystem operation?
 596  */
 597 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
 598
 599 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
 600
 601 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
 602                            struct file *file, bool *refreshed);