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