fs/fuse/fuse_i.h

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2005  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/wait.h>
  12 #include <linux/list.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/mm.h>
  15 #include <linux/backing-dev.h>
  16 #include <asm/semaphore.h>
  17
  18 /** Max number of pages that can be used in a single read request */
  19 #define FUSE_MAX_PAGES_PER_REQ 32
  20
  21 /** If more requests are outstanding, then the operation will block */
  22 #define FUSE_MAX_OUTSTANDING 10
  23
  24 /** It could be as large as PATH_MAX, but would that have any uses? */
  25 #define FUSE_NAME_MAX 1024
  26
  27 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
  28     module will check permissions based on the file mode.  Otherwise no
  29     permission checking is done in the kernel */
  30 #define FUSE_DEFAULT_PERMISSIONS (1 << 0)
  31
  32 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user
  33     doing the mount will be allowed to access the filesystem */
  34 #define FUSE_ALLOW_OTHER         (1 << 1)
  35
  36
  37 /** FUSE inode */
  38 struct fuse_inode {
  39         /** Inode data */
  40         struct inode inode;
  41
  42         /** Unique ID, which identifies the inode between userspace
  43          * and kernel */
  44         u64 nodeid;
  45
  46         /** Number of lookups on this inode */
  47         u64 nlookup;
  48
  49         /** The request used for sending the FORGET message */
  50         struct fuse_req *forget_req;
  51
  52         /** Time in jiffies until the file attributes are valid */
  53         unsigned long i_time;
  54 };
  55
  56 /** FUSE specific file data */
  57 struct fuse_file {
  58         /** Request reserved for flush and release */
  59         struct fuse_req *release_req;
  60
  61         /** File handle used by userspace */
  62         u64 fh;
  63 };
  64
  65 /** One input argument of a request */
  66 struct fuse_in_arg {
  67         unsigned size;
  68         const void *value;
  69 };
  70
  71 /** The request input */
  72 struct fuse_in {
  73         /** The request header */
  74         struct fuse_in_header h;
  75
  76         /** True if the data for the last argument is in req->pages */
  77         unsigned argpages:1;
  78
  79         /** Number of arguments */
  80         unsigned numargs;
  81
  82         /** Array of arguments */
  83         struct fuse_in_arg args[3];
  84 };
  85
  86 /** One output argument of a request */
  87 struct fuse_arg {
  88         unsigned size;
  89         void *value;
  90 };
  91
  92 /** The request output */
  93 struct fuse_out {
  94         /** Header returned from userspace */
  95         struct fuse_out_header h;
  96
  97         /*
  98          * The following bitfields are not changed during the request
  99          * processing
 100          */
 101
 102         /** Last argument is variable length (can be shorter than
 103             arg->size) */
 104         unsigned argvar:1;
 105
 106         /** Last argument is a list of pages to copy data to */
 107         unsigned argpages:1;
 108
 109         /** Zero partially or not copied pages */
 110         unsigned page_zeroing:1;
 111
 112         /** Number or arguments */
 113         unsigned numargs;
 114
 115         /** Array of arguments */
 116         struct fuse_arg args[3];
 117 };
 118
 119 /** The request state */
 120 enum fuse_req_state {
 121         FUSE_REQ_INIT = 0,
 122         FUSE_REQ_PENDING,
 123         FUSE_REQ_READING,
 124         FUSE_REQ_SENT,
 125         FUSE_REQ_FINISHED
 126 };
 127
 128 struct fuse_conn;
 129
 130 /**
 131  * A request to the client
 132  */
 133 struct fuse_req {
 134         /** This can be on either unused_list, pending processing or
 135             io lists in fuse_conn */
 136         struct list_head list;
 137
 138         /** Entry on the background list */
 139         struct list_head bg_entry;
 140
 141         /** refcount */
 142         atomic_t count;
 143
 144         /*
 145          * The following bitfields are either set once before the
 146          * request is queued or setting/clearing them is protected by
 147          * fuse_lock
 148          */
 149
 150         /** True if the request has reply */
 151         unsigned isreply:1;
 152
 153         /** The request is preallocated */
 154         unsigned preallocated:1;
 155
 156         /** The request was interrupted */
 157         unsigned interrupted:1;
 158
 159         /** Request is sent in the background */
 160         unsigned background:1;
 161
 162         /** Data is being copied to/from the request */
 163         unsigned locked:1;
 164
 165         /** State of the request */
 166         enum fuse_req_state state;
 167
 168         /** The request input */
 169         struct fuse_in in;
 170
 171         /** The request output */
 172         struct fuse_out out;
 173
 174         /** Used to wake up the task waiting for completion of request*/
 175         wait_queue_head_t waitq;
 176
 177         /** Data for asynchronous requests */
 178         union {
 179                 struct fuse_forget_in forget_in;
 180                 struct fuse_release_in release_in;
 181                 struct fuse_init_in init_in;
 182                 struct fuse_init_out init_out;
 183                 struct fuse_read_in read_in;
 184         } misc;
 185
 186         /** page vector */
 187         struct page *pages[FUSE_MAX_PAGES_PER_REQ];
 188
 189         /** number of pages in vector */
 190         unsigned num_pages;
 191
 192         /** offset of data on first page */
 193         unsigned page_offset;
 194
 195         /** Inode used in the request */
 196         struct inode *inode;
 197
 198         /** Second inode used in the request (or NULL) */
 199         struct inode *inode2;
 200
 201         /** File used in the request (or NULL) */
 202         struct file *file;
 203
 204         /** Request completion callback */
 205         void (*end)(struct fuse_conn *, struct fuse_req *);
 206 };
 207
 208 /**
 209  * A Fuse connection.
 210  *
 211  * This structure is created, when the filesystem is mounted, and is
 212  * destroyed, when the client device is closed and the filesystem is
 213  * unmounted.
 214  */
 215 struct fuse_conn {
 216         /** The user id for this mount */
 217         uid_t user_id;
 218
 219         /** The group id for this mount */
 220         gid_t group_id;
 221
 222         /** The fuse mount flags for this mount */
 223         unsigned flags;
 224
 225         /** Maximum read size */
 226         unsigned max_read;
 227
 228         /** Maximum write size */
 229         unsigned max_write;
 230
 231         /** Readers of the connection are waiting on this */
 232         wait_queue_head_t waitq;
 233
 234         /** The list of pending requests */
 235         struct list_head pending;
 236
 237         /** The list of requests being processed */
 238         struct list_head processing;
 239
 240         /** The list of requests under I/O */
 241         struct list_head io;
 242
 243         /** Requests put in the background (RELEASE or any other
 244             interrupted request) */
 245         struct list_head background;
 246
 247         /** Controls the maximum number of outstanding requests */
 248         struct semaphore outstanding_sem;
 249
 250         /** This counts the number of outstanding requests if
 251             outstanding_sem would go negative */
 252         unsigned outstanding_debt;
 253
 254         /** RW semaphore for exclusion with fuse_put_super() */
 255         struct rw_semaphore sbput_sem;
 256
 257         /** The list of unused requests */
 258         struct list_head unused_list;
 259
 260         /** The next unique request id */
 261         u64 reqctr;
 262
 263         /** Mount is active */
 264         unsigned mounted;
 265
 266         /** Connection established, cleared on umount, connection
 267             abort and device release */
 268         unsigned connected;
 269
 270         /** Connection failed (version mismatch).  Cannot race with
 271             setting other bitfields since it is only set once in INIT
 272             reply, before any other request, and never cleared */
 273         unsigned conn_error : 1;
 274
 275         /*
 276          * The following bitfields are only for optimization purposes
 277          * and hence races in setting them will not cause malfunction
 278          */
 279
 280         /** Is fsync not implemented by fs? */
 281         unsigned no_fsync : 1;
 282
 283         /** Is fsyncdir not implemented by fs? */
 284         unsigned no_fsyncdir : 1;
 285
 286         /** Is flush not implemented by fs? */
 287         unsigned no_flush : 1;
 288
 289         /** Is setxattr not implemented by fs? */
 290         unsigned no_setxattr : 1;
 291
 292         /** Is getxattr not implemented by fs? */
 293         unsigned no_getxattr : 1;
 294
 295         /** Is listxattr not implemented by fs? */
 296         unsigned no_listxattr : 1;
 297
 298         /** Is removexattr not implemented by fs? */
 299         unsigned no_removexattr : 1;
 300
 301         /** Is access not implemented by fs? */
 302         unsigned no_access : 1;
 303
 304         /** Is create not implemented by fs? */
 305         unsigned no_create : 1;
 306
 307         /** The number of requests waiting for completion */
 308         atomic_t num_waiting;
 309
 310         /** Negotiated minor version */
 311         unsigned minor;
 312
 313         /** Backing dev info */
 314         struct backing_dev_info bdi;
 315
 316         /** kobject */
 317         struct kobject kobj;
 318 };
 319
 320 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 321 {
 322         return sb->s_fs_info;
 323 }
 324
 325 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 326 {
 327         return get_fuse_conn_super(inode->i_sb);
 328 }
 329
 330 static inline struct fuse_conn *get_fuse_conn_kobj(struct kobject *obj)
 331 {
 332         return container_of(obj, struct fuse_conn, kobj);
 333 }
 334
 335 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 336 {
 337         return container_of(inode, struct fuse_inode, inode);
 338 }
 339
 340 static inline u64 get_node_id(struct inode *inode)
 341 {
 342         return get_fuse_inode(inode)->nodeid;
 343 }
 344
 345 /** Device operations */
 346 extern struct file_operations fuse_dev_operations;
 347
 348 /**
 349  * This is the single global spinlock which protects FUSE's structures
 350  *
 351  * The following data is protected by this lock:
 352  *
 353  *  - the private_data field of the device file
 354  *  - the s_fs_info field of the super block
 355  *  - unused_list, pending, processing lists in fuse_conn
 356  *  - background list in fuse_conn
 357  *  - the unique request ID counter reqctr in fuse_conn
 358  *  - the sb (super_block) field in fuse_conn
 359  *  - the file (device file) field in fuse_conn
 360  */
 361 extern spinlock_t fuse_lock;
 362
 363 /**
 364  * Get a filled in inode
 365  */
 366 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 367                         int generation, struct fuse_attr *attr);
 368
 369 /**
 370  * Send FORGET command
 371  */
 372 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 373                       unsigned long nodeid, u64 nlookup);
 374
 375 /**
 376  * Initialize READ or READDIR request
 377  */
 378 void fuse_read_fill(struct fuse_req *req, struct file *file,
 379                     struct inode *inode, loff_t pos, size_t count, int opcode);
 380
 381 /**
 382  * Send OPEN or OPENDIR request
 383  */
 384 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
 385
 386 struct fuse_file *fuse_file_alloc(void);
 387 void fuse_file_free(struct fuse_file *ff);
 388 void fuse_finish_open(struct inode *inode, struct file *file,
 389                       struct fuse_file *ff, struct fuse_open_out *outarg);
 390
 391 /**
 392  * Send a RELEASE request
 393  */
 394 void fuse_send_release(struct fuse_conn *fc, struct fuse_file *ff,
 395                        u64 nodeid, struct inode *inode, int flags, int isdir);
 396
 397 /**
 398  * Send RELEASE or RELEASEDIR request
 399  */
 400 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
 401
 402 /**
 403  * Send FSYNC or FSYNCDIR request
 404  */
 405 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 406                       int isdir);
 407
 408 /**
 409  * Initialize file operations on a regular file
 410  */
 411 void fuse_init_file_inode(struct inode *inode);
 412
 413 /**
 414  * Initialize inode operations on regular files and special files
 415  */
 416 void fuse_init_common(struct inode *inode);
 417
 418 /**
 419  * Initialize inode and file operations on a directory
 420  */
 421 void fuse_init_dir(struct inode *inode);
 422
 423 /**
 424  * Initialize inode operations on a symlink
 425  */
 426 void fuse_init_symlink(struct inode *inode);
 427
 428 /**
 429  * Change attributes of an inode
 430  */
 431 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
 432
 433 /**
 434  * Initialize the client device
 435  */
 436 int fuse_dev_init(void);
 437
 438 /**
 439  * Cleanup the client device
 440  */
 441 void fuse_dev_cleanup(void);
 442
 443 /**
 444  * Allocate a request
 445  */
 446 struct fuse_req *fuse_request_alloc(void);
 447
 448 /**
 449  * Free a request
 450  */
 451 void fuse_request_free(struct fuse_req *req);
 452
 453 /**
 454  * Reinitialize a request, the preallocated flag is left unmodified
 455  */
 456 void fuse_reset_request(struct fuse_req *req);
 457
 458 /**
 459  * Reserve a preallocated request
 460  */
 461 struct fuse_req *fuse_get_request(struct fuse_conn *fc);
 462
 463 /**
 464  * Decrement reference count of a request.  If count goes to zero put
 465  * on unused list (preallocated) or free request (not preallocated).
 466  */
 467 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
 468
 469 /**
 470  * Send a request (synchronous)
 471  */
 472 void request_send(struct fuse_conn *fc, struct fuse_req *req);
 473
 474 /**
 475  * Send a request with no reply
 476  */
 477 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
 478
 479 /**
 480  * Send a request in the background
 481  */
 482 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 483
 484 /**
 485  * Release inodes and file associated with background request
 486  */
 487 void fuse_release_background(struct fuse_req *req);
 488
 489 /* Abort all requests */
 490 void fuse_abort_conn(struct fuse_conn *fc);
 491
 492 /**
 493  * Get the attributes of a file
 494  */
 495 int fuse_do_getattr(struct inode *inode);
 496
 497 /**
 498  * Invalidate inode attributes
 499  */
 500 void fuse_invalidate_attr(struct inode *inode);