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