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