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