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