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         /** Last argument is variable length (can be shorter than
  98             arg->size) */
  99         unsigned argvar:1;
 100
 101         /** Last argument is a list of pages to copy data to */
 102         unsigned argpages:1;
 103
 104         /** Zero partially or not copied pages */
 105         unsigned page_zeroing:1;
 106
 107         /** Number or arguments */
 108         unsigned numargs;
 109
 110         /** Array of arguments */
 111         struct fuse_arg args[3];
 112 };
 113
 114 /** The request state */
 115 enum fuse_req_state {
 116         FUSE_REQ_INIT = 0,
 117         FUSE_REQ_PENDING,
 118         FUSE_REQ_READING,
 119         FUSE_REQ_SENT,
 120         FUSE_REQ_FINISHED
 121 };
 122
 123 /**
 124  * A request to the client
 125  */
 126 struct fuse_req {
 127         /** This can be on either unused_list, pending processing or
 128             io lists in fuse_conn */
 129         struct list_head list;
 130
 131         /** Entry on the background list */
 132         struct list_head bg_entry;
 133
 134         /** refcount */
 135         atomic_t count;
 136
 137         /** True if the request has reply */
 138         unsigned isreply:1;
 139
 140         /** The request is preallocated */
 141         unsigned preallocated:1;
 142
 143         /** The request was interrupted */
 144         unsigned interrupted:1;
 145
 146         /** Request is sent in the background */
 147         unsigned background:1;
 148
 149         /** Data is being copied to/from the request */
 150         unsigned locked:1;
 151
 152         /** State of the request */
 153         enum fuse_req_state state;
 154
 155         /** The request input */
 156         struct fuse_in in;
 157
 158         /** The request output */
 159         struct fuse_out out;
 160
 161         /** Used to wake up the task waiting for completion of request*/
 162         wait_queue_head_t waitq;
 163
 164         /** Data for asynchronous requests */
 165         union {
 166                 struct fuse_forget_in forget_in;
 167                 struct fuse_release_in release_in;
 168                 struct fuse_init_in init_in;
 169                 struct fuse_init_out init_out;
 170         } misc;
 171
 172         /** page vector */
 173         struct page *pages[FUSE_MAX_PAGES_PER_REQ];
 174
 175         /** number of pages in vector */
 176         unsigned num_pages;
 177
 178         /** offset of data on first page */
 179         unsigned page_offset;
 180
 181         /** Inode used in the request */
 182         struct inode *inode;
 183
 184         /** Second inode used in the request (or NULL) */
 185         struct inode *inode2;
 186
 187         /** File used in the request (or NULL) */
 188         struct file *file;
 189 };
 190
 191 /**
 192  * A Fuse connection.
 193  *
 194  * This structure is created, when the filesystem is mounted, and is
 195  * destroyed, when the client device is closed and the filesystem is
 196  * unmounted.
 197  */
 198 struct fuse_conn {
 199         /** Reference count */
 200         int count;
 201
 202         /** The user id for this mount */
 203         uid_t user_id;
 204
 205         /** The group id for this mount */
 206         gid_t group_id;
 207
 208         /** The fuse mount flags for this mount */
 209         unsigned flags;
 210
 211         /** Maximum read size */
 212         unsigned max_read;
 213
 214         /** Maximum write size */
 215         unsigned max_write;
 216
 217         /** Readers of the connection are waiting on this */
 218         wait_queue_head_t waitq;
 219
 220         /** The list of pending requests */
 221         struct list_head pending;
 222
 223         /** The list of requests being processed */
 224         struct list_head processing;
 225
 226         /** The list of requests under I/O */
 227         struct list_head io;
 228
 229         /** Requests put in the background (RELEASE or any other
 230             interrupted request) */
 231         struct list_head background;
 232
 233         /** Controls the maximum number of outstanding requests */
 234         struct semaphore outstanding_sem;
 235
 236         /** This counts the number of outstanding requests if
 237             outstanding_sem would go negative */
 238         unsigned outstanding_debt;
 239
 240         /** RW semaphore for exclusion with fuse_put_super() */
 241         struct rw_semaphore sbput_sem;
 242
 243         /** The list of unused requests */
 244         struct list_head unused_list;
 245
 246         /** The next unique request id */
 247         u64 reqctr;
 248
 249         /** Mount is active */
 250         unsigned mounted : 1;
 251
 252         /** Connection established */
 253         unsigned connected : 1;
 254
 255         /** Connection failed (version mismatch) */
 256         unsigned conn_error : 1;
 257
 258         /** Is fsync not implemented by fs? */
 259         unsigned no_fsync : 1;
 260
 261         /** Is fsyncdir not implemented by fs? */
 262         unsigned no_fsyncdir : 1;
 263
 264         /** Is flush not implemented by fs? */
 265         unsigned no_flush : 1;
 266
 267         /** Is setxattr not implemented by fs? */
 268         unsigned no_setxattr : 1;
 269
 270         /** Is getxattr not implemented by fs? */
 271         unsigned no_getxattr : 1;
 272
 273         /** Is listxattr not implemented by fs? */
 274         unsigned no_listxattr : 1;
 275
 276         /** Is removexattr not implemented by fs? */
 277         unsigned no_removexattr : 1;
 278
 279         /** Is access not implemented by fs? */
 280         unsigned no_access : 1;
 281
 282         /** Is create not implemented by fs? */
 283         unsigned no_create : 1;
 284
 285         /** Negotiated minor version */
 286         unsigned minor;
 287
 288         /** Backing dev info */
 289         struct backing_dev_info bdi;
 290 };
 291
 292 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 293 {
 294         return sb->s_fs_info;
 295 }
 296
 297 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 298 {
 299         return get_fuse_conn_super(inode->i_sb);
 300 }
 301
 302 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 303 {
 304         return container_of(inode, struct fuse_inode, inode);
 305 }
 306
 307 static inline u64 get_node_id(struct inode *inode)
 308 {
 309         return get_fuse_inode(inode)->nodeid;
 310 }
 311
 312 /** Device operations */
 313 extern struct file_operations fuse_dev_operations;
 314
 315 /**
 316  * This is the single global spinlock which protects FUSE's structures
 317  *
 318  * The following data is protected by this lock:
 319  *
 320  *  - the private_data field of the device file
 321  *  - the s_fs_info field of the super block
 322  *  - unused_list, pending, processing lists in fuse_conn
 323  *  - background list in fuse_conn
 324  *  - the unique request ID counter reqctr in fuse_conn
 325  *  - the sb (super_block) field in fuse_conn
 326  *  - the file (device file) field in fuse_conn
 327  */
 328 extern spinlock_t fuse_lock;
 329
 330 /**
 331  * Get a filled in inode
 332  */
 333 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 334                         int generation, struct fuse_attr *attr);
 335
 336 /**
 337  * Send FORGET command
 338  */
 339 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 340                       unsigned long nodeid, u64 nlookup);
 341
 342 /**
 343  * Send READ or READDIR request
 344  */
 345 size_t fuse_send_read_common(struct fuse_req *req, struct file *file,
 346                              struct inode *inode, loff_t pos, size_t count,
 347                              int isdir);
 348
 349 /**
 350  * Send OPEN or OPENDIR request
 351  */
 352 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
 353
 354 struct fuse_file *fuse_file_alloc(void);
 355 void fuse_file_free(struct fuse_file *ff);
 356 void fuse_finish_open(struct inode *inode, struct file *file,
 357                       struct fuse_file *ff, struct fuse_open_out *outarg);
 358
 359 /**
 360  * Send a RELEASE request
 361  */
 362 void fuse_send_release(struct fuse_conn *fc, struct fuse_file *ff,
 363                        u64 nodeid, struct inode *inode, int flags, int isdir);
 364
 365 /**
 366  * Send RELEASE or RELEASEDIR request
 367  */
 368 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
 369
 370 /**
 371  * Send FSYNC or FSYNCDIR request
 372  */
 373 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 374                       int isdir);
 375
 376 /**
 377  * Initialize file operations on a regular file
 378  */
 379 void fuse_init_file_inode(struct inode *inode);
 380
 381 /**
 382  * Initialize inode operations on regular files and special files
 383  */
 384 void fuse_init_common(struct inode *inode);
 385
 386 /**
 387  * Initialize inode and file operations on a directory
 388  */
 389 void fuse_init_dir(struct inode *inode);
 390
 391 /**
 392  * Initialize inode operations on a symlink
 393  */
 394 void fuse_init_symlink(struct inode *inode);
 395
 396 /**
 397  * Change attributes of an inode
 398  */
 399 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
 400
 401 /**
 402  * Check if the connection can be released, and if yes, then free the
 403  * connection structure
 404  */
 405 void fuse_release_conn(struct fuse_conn *fc);
 406
 407 /**
 408  * Initialize the client device
 409  */
 410 int fuse_dev_init(void);
 411
 412 /**
 413  * Cleanup the client device
 414  */
 415 void fuse_dev_cleanup(void);
 416
 417 /**
 418  * Allocate a request
 419  */
 420 struct fuse_req *fuse_request_alloc(void);
 421
 422 /**
 423  * Free a request
 424  */
 425 void fuse_request_free(struct fuse_req *req);
 426
 427 /**
 428  * Reinitialize a request, the preallocated flag is left unmodified
 429  */
 430 void fuse_reset_request(struct fuse_req *req);
 431
 432 /**
 433  * Reserve a preallocated request
 434  */
 435 struct fuse_req *fuse_get_request(struct fuse_conn *fc);
 436
 437 /**
 438  * Decrement reference count of a request.  If count goes to zero put
 439  * on unused list (preallocated) or free request (not preallocated).
 440  */
 441 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
 442
 443 /**
 444  * Send a request (synchronous)
 445  */
 446 void request_send(struct fuse_conn *fc, struct fuse_req *req);
 447
 448 /**
 449  * Send a request with no reply
 450  */
 451 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
 452
 453 /**
 454  * Send a request in the background
 455  */
 456 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 457
 458 /**
 459  * Release inodes and file associated with background request
 460  */
 461 void fuse_release_background(struct fuse_req *req);
 462
 463 /**
 464  * Get the attributes of a file
 465  */
 466 int fuse_do_getattr(struct inode *inode);
 467
 468 /**
 469  * Invalidate inode attributes
 470  */
 471 void fuse_invalidate_attr(struct inode *inode);
 472
 473 /**
 474  * Send the INIT message
 475  */
 476 void fuse_send_init(struct fuse_conn *fc);