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 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
  25     module will check permissions based on the file mode.  Otherwise no
  26     permission checking is done in the kernel */
  27 #define FUSE_DEFAULT_PERMISSIONS (1 << 0)
  28
  29 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user
  30     doing the mount will be allowed to access the filesystem */
  31 #define FUSE_ALLOW_OTHER         (1 << 1)
  32
  33
  34 /** FUSE inode */
  35 struct fuse_inode {
  36         /** Inode data */
  37         struct inode inode;
  38
  39         /** Unique ID, which identifies the inode between userspace
  40          * and kernel */
  41         u64 nodeid;
  42
  43         /** Number of lookups on this inode */
  44         u64 nlookup;
  45
  46         /** The request used for sending the FORGET message */
  47         struct fuse_req *forget_req;
  48
  49         /** Time in jiffies until the file attributes are valid */
  50         unsigned long i_time;
  51 };
  52
  53 /** FUSE specific file data */
  54 struct fuse_file {
  55         /** Request reserved for flush and release */
  56         struct fuse_req *release_req;
  57
  58         /** File handle used by userspace */
  59         u64 fh;
  60 };
  61
  62 /** One input argument of a request */
  63 struct fuse_in_arg {
  64         unsigned size;
  65         const void *value;
  66 };
  67
  68 /** The request input */
  69 struct fuse_in {
  70         /** The request header */
  71         struct fuse_in_header h;
  72
  73         /** True if the data for the last argument is in req->pages */
  74         unsigned argpages:1;
  75
  76         /** Number of arguments */
  77         unsigned numargs;
  78
  79         /** Array of arguments */
  80         struct fuse_in_arg args[3];
  81 };
  82
  83 /** One output argument of a request */
  84 struct fuse_arg {
  85         unsigned size;
  86         void *value;
  87 };
  88
  89 /** The request output */
  90 struct fuse_out {
  91         /** Header returned from userspace */
  92         struct fuse_out_header h;
  93
  94         /** Last argument is variable length (can be shorter than
  95             arg->size) */
  96         unsigned argvar:1;
  97
  98         /** Last argument is a list of pages to copy data to */
  99         unsigned argpages:1;
 100
 101         /** Zero partially or not copied pages */
 102         unsigned page_zeroing:1;
 103
 104         /** Number or arguments */
 105         unsigned numargs;
 106
 107         /** Array of arguments */
 108         struct fuse_arg args[3];
 109 };
 110
 111 struct fuse_req;
 112 struct fuse_conn;
 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_out init_in_out;
 163         } misc;
 164
 165         /** page vector */
 166         struct page *pages[FUSE_MAX_PAGES_PER_REQ];
 167
 168         /** number of pages in vector */
 169         unsigned num_pages;
 170
 171         /** offset of data on first page */
 172         unsigned page_offset;
 173
 174         /** Inode used in the request */
 175         struct inode *inode;
 176
 177         /** Second inode used in the request (or NULL) */
 178         struct inode *inode2;
 179
 180         /** File used in the request (or NULL) */
 181         struct file *file;
 182 };
 183
 184 /**
 185  * A Fuse connection.
 186  *
 187  * This structure is created, when the filesystem is mounted, and is
 188  * destroyed, when the client device is closed and the filesystem is
 189  * unmounted.
 190  */
 191 struct fuse_conn {
 192         /** Reference count */
 193         int count;
 194
 195         /** The user id for this mount */
 196         uid_t user_id;
 197
 198         /** The group id for this mount */
 199         gid_t group_id;
 200
 201         /** The fuse mount flags for this mount */
 202         unsigned flags;
 203
 204         /** Maximum read size */
 205         unsigned max_read;
 206
 207         /** Maximum write size */
 208         unsigned max_write;
 209
 210         /** Readers of the connection are waiting on this */
 211         wait_queue_head_t waitq;
 212
 213         /** The list of pending requests */
 214         struct list_head pending;
 215
 216         /** The list of requests being processed */
 217         struct list_head processing;
 218
 219         /** Requests put in the background (RELEASE or any other
 220             interrupted request) */
 221         struct list_head background;
 222
 223         /** Controls the maximum number of outstanding requests */
 224         struct semaphore outstanding_sem;
 225
 226         /** This counts the number of outstanding requests if
 227             outstanding_sem would go negative */
 228         unsigned outstanding_debt;
 229
 230         /** RW semaphore for exclusion with fuse_put_super() */
 231         struct rw_semaphore sbput_sem;
 232
 233         /** The list of unused requests */
 234         struct list_head unused_list;
 235
 236         /** The next unique request id */
 237         u64 reqctr;
 238
 239         /** Mount is active */
 240         unsigned mounted : 1;
 241
 242         /** Connection established */
 243         unsigned connected : 1;
 244
 245         /** Connection failed (version mismatch) */
 246         unsigned conn_error : 1;
 247
 248         /** Is fsync not implemented by fs? */
 249         unsigned no_fsync : 1;
 250
 251         /** Is fsyncdir not implemented by fs? */
 252         unsigned no_fsyncdir : 1;
 253
 254         /** Is flush not implemented by fs? */
 255         unsigned no_flush : 1;
 256
 257         /** Is setxattr not implemented by fs? */
 258         unsigned no_setxattr : 1;
 259
 260         /** Is getxattr not implemented by fs? */
 261         unsigned no_getxattr : 1;
 262
 263         /** Is listxattr not implemented by fs? */
 264         unsigned no_listxattr : 1;
 265
 266         /** Is removexattr not implemented by fs? */
 267         unsigned no_removexattr : 1;
 268
 269         /** Backing dev info */
 270         struct backing_dev_info bdi;
 271 };
 272
 273 static inline struct fuse_conn **get_fuse_conn_super_p(struct super_block *sb)
 274 {
 275         return (struct fuse_conn **) &sb->s_fs_info;
 276 }
 277
 278 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 279 {
 280         return *get_fuse_conn_super_p(sb);
 281 }
 282
 283 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 284 {
 285         return get_fuse_conn_super(inode->i_sb);
 286 }
 287
 288 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 289 {
 290         return container_of(inode, struct fuse_inode, inode);
 291 }
 292
 293 static inline u64 get_node_id(struct inode *inode)
 294 {
 295         return get_fuse_inode(inode)->nodeid;
 296 }
 297
 298 /** Device operations */
 299 extern struct file_operations fuse_dev_operations;
 300
 301 /**
 302  * This is the single global spinlock which protects FUSE's structures
 303  *
 304  * The following data is protected by this lock:
 305  *
 306  *  - the private_data field of the device file
 307  *  - the s_fs_info field of the super block
 308  *  - unused_list, pending, processing lists in fuse_conn
 309  *  - background list in fuse_conn
 310  *  - the unique request ID counter reqctr in fuse_conn
 311  *  - the sb (super_block) field in fuse_conn
 312  *  - the file (device file) field in fuse_conn
 313  */
 314 extern spinlock_t fuse_lock;
 315
 316 /**
 317  * Get a filled in inode
 318  */
 319 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 320                         int generation, struct fuse_attr *attr);
 321
 322 /**
 323  * Send FORGET command
 324  */
 325 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 326                       unsigned long nodeid, u64 nlookup);
 327
 328 /**
 329  * Send READ or READDIR request
 330  */
 331 size_t fuse_send_read_common(struct fuse_req *req, struct file *file,
 332                              struct inode *inode, loff_t pos, size_t count,
 333                              int isdir);
 334
 335 /**
 336  * Send OPEN or OPENDIR request
 337  */
 338 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
 339
 340 /**
 341  * Send RELEASE or RELEASEDIR request
 342  */
 343 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
 344
 345 /**
 346  * Send FSYNC or FSYNCDIR request
 347  */
 348 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 349                       int isdir);
 350
 351 /**
 352  * Initialise file operations on a regular file
 353  */
 354 void fuse_init_file_inode(struct inode *inode);
 355
 356 /**
 357  * Initialise inode operations on regular files and special files
 358  */
 359 void fuse_init_common(struct inode *inode);
 360
 361 /**
 362  * Initialise inode and file operations on a directory
 363  */
 364 void fuse_init_dir(struct inode *inode);
 365
 366 /**
 367  * Initialise inode operations on a symlink
 368  */
 369 void fuse_init_symlink(struct inode *inode);
 370
 371 /**
 372  * Change attributes of an inode
 373  */
 374 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
 375
 376 /**
 377  * Check if the connection can be released, and if yes, then free the
 378  * connection structure
 379  */
 380 void fuse_release_conn(struct fuse_conn *fc);
 381
 382 /**
 383  * Initialize the client device
 384  */
 385 int fuse_dev_init(void);
 386
 387 /**
 388  * Cleanup the client device
 389  */
 390 void fuse_dev_cleanup(void);
 391
 392 /**
 393  * Allocate a request
 394  */
 395 struct fuse_req *fuse_request_alloc(void);
 396
 397 /**
 398  * Free a request
 399  */
 400 void fuse_request_free(struct fuse_req *req);
 401
 402 /**
 403  * Reinitialize a request, the preallocated flag is left unmodified
 404  */
 405 void fuse_reset_request(struct fuse_req *req);
 406
 407 /**
 408  * Reserve a preallocated request
 409  */
 410 struct fuse_req *fuse_get_request(struct fuse_conn *fc);
 411
 412 /**
 413  * Decrement reference count of a request.  If count goes to zero put
 414  * on unused list (preallocated) or free reqest (not preallocated).
 415  */
 416 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
 417
 418 /**
 419  * Send a request (synchronous)
 420  */
 421 void request_send(struct fuse_conn *fc, struct fuse_req *req);
 422
 423 /**
 424  * Send a request with no reply
 425  */
 426 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
 427
 428 /**
 429  * Send a request in the background
 430  */
 431 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 432
 433 /**
 434  * Release inodes and file assiciated with background request
 435  */
 436 void fuse_release_background(struct fuse_req *req);
 437
 438 /**
 439  * Get the attributes of a file
 440  */
 441 int fuse_do_getattr(struct inode *inode);
 442
 443 /**
 444  * Invalidate inode attributes
 445  */
 446 void fuse_invalidate_attr(struct inode *inode);
 447
 448 /**
 449  * Send the INIT message
 450  */
 451 void fuse_send_init(struct fuse_conn *fc);