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