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 /** If the FUSE_KERNEL_CACHE flag is given, then cached data will not
  34     be flushed on open */
  35 #define FUSE_KERNEL_CACHE        (1 << 2)
  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 struct fuse_req;
 115 struct fuse_conn;
 116
 117 /**
 118  * A request to the client
 119  */
 120 struct fuse_req {
 121         /** This can be on either unused_list, pending or processing
 122             lists in fuse_conn */
 123         struct list_head list;
 124
 125         /** Entry on the background list */
 126         struct list_head bg_entry;
 127
 128         /** refcount */
 129         atomic_t count;
 130
 131         /** True if the request has reply */
 132         unsigned isreply:1;
 133
 134         /** The request is preallocated */
 135         unsigned preallocated:1;
 136
 137         /** The request was interrupted */
 138         unsigned interrupted:1;
 139
 140         /** Request is sent in the background */
 141         unsigned background:1;
 142
 143         /** Data is being copied to/from the request */
 144         unsigned locked:1;
 145
 146         /** Request has been sent to userspace */
 147         unsigned sent:1;
 148
 149         /** The request is finished */
 150         unsigned finished:1;
 151
 152         /** The request input */
 153         struct fuse_in in;
 154
 155         /** The request output */
 156         struct fuse_out out;
 157
 158         /** Used to wake up the task waiting for completion of request*/
 159         wait_queue_head_t waitq;
 160
 161         /** Data for asynchronous requests */
 162         union {
 163                 struct fuse_forget_in forget_in;
 164                 struct fuse_release_in release_in;
 165                 struct fuse_init_in_out init_in_out;
 166         } misc;
 167
 168         /** page vector */
 169         struct page *pages[FUSE_MAX_PAGES_PER_REQ];
 170
 171         /** number of pages in vector */
 172         unsigned num_pages;
 173
 174         /** offset of data on first page */
 175         unsigned page_offset;
 176
 177         /** Inode used in the request */
 178         struct inode *inode;
 179
 180         /** Second inode used in the request (or NULL) */
 181         struct inode *inode2;
 182
 183         /** File used in the request (or NULL) */
 184         struct file *file;
 185 };
 186
 187 /**
 188  * A Fuse connection.
 189  *
 190  * This structure is created, when the filesystem is mounted, and is
 191  * destroyed, when the client device is closed and the filesystem is
 192  * unmounted.
 193  */
 194 struct fuse_conn {
 195         /** Reference count */
 196         int count;
 197
 198         /** The user id for this mount */
 199         uid_t user_id;
 200
 201         /** The fuse mount flags for this mount */
 202         unsigned flags;
 203
 204         /** Readers of the connection are waiting on this */
 205         wait_queue_head_t waitq;
 206
 207         /** The list of pending requests */
 208         struct list_head pending;
 209
 210         /** The list of requests being processed */
 211         struct list_head processing;
 212
 213         /** Requests put in the background (RELEASE or any other
 214             interrupted request) */
 215         struct list_head background;
 216
 217         /** Controls the maximum number of outstanding requests */
 218         struct semaphore outstanding_sem;
 219
 220         /** This counts the number of outstanding requests if
 221             outstanding_sem would go negative */
 222         unsigned outstanding_debt;
 223
 224         /** RW semaphore for exclusion with fuse_put_super() */
 225         struct rw_semaphore sbput_sem;
 226
 227         /** The list of unused requests */
 228         struct list_head unused_list;
 229
 230         /** The next unique request id */
 231         u64 reqctr;
 232
 233         /** Mount is active */
 234         unsigned mounted : 1;
 235
 236         /** Connection established */
 237         unsigned connected : 1;
 238
 239         /** Connection failed (version mismatch) */
 240         unsigned conn_error : 1;
 241
 242         /** Is fsync not implemented by fs? */
 243         unsigned no_fsync : 1;
 244
 245         /** Is flush not implemented by fs? */
 246         unsigned no_flush : 1;
 247
 248         /** Is setxattr not implemented by fs? */
 249         unsigned no_setxattr : 1;
 250
 251         /** Is getxattr not implemented by fs? */
 252         unsigned no_getxattr : 1;
 253
 254         /** Is listxattr not implemented by fs? */
 255         unsigned no_listxattr : 1;
 256
 257         /** Is removexattr not implemented by fs? */
 258         unsigned no_removexattr : 1;
 259
 260         /** Backing dev info */
 261         struct backing_dev_info bdi;
 262 };
 263
 264 struct fuse_getdir_out_i {
 265         int fd;
 266         void *file; /* Used by kernel only */
 267 };
 268
 269 static inline struct fuse_conn **get_fuse_conn_super_p(struct super_block *sb)
 270 {
 271         return (struct fuse_conn **) &sb->s_fs_info;
 272 }
 273
 274 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 275 {
 276         return *get_fuse_conn_super_p(sb);
 277 }
 278
 279 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 280 {
 281         return get_fuse_conn_super(inode->i_sb);
 282 }
 283
 284 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 285 {
 286         return container_of(inode, struct fuse_inode, inode);
 287 }
 288
 289 static inline u64 get_node_id(struct inode *inode)
 290 {
 291         return get_fuse_inode(inode)->nodeid;
 292 }
 293
 294 /** Device operations */
 295 extern struct file_operations fuse_dev_operations;
 296
 297 /**
 298  * This is the single global spinlock which protects FUSE's structures
 299  *
 300  * The following data is protected by this lock:
 301  *
 302  *  - the private_data field of the device file
 303  *  - the s_fs_info field of the super block
 304  *  - unused_list, pending, processing lists in fuse_conn
 305  *  - background list in fuse_conn
 306  *  - the unique request ID counter reqctr in fuse_conn
 307  *  - the sb (super_block) field in fuse_conn
 308  *  - the file (device file) field in fuse_conn
 309  */
 310 extern spinlock_t fuse_lock;
 311
 312 /**
 313  * Get a filled in inode
 314  */
 315 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 316                         int generation, struct fuse_attr *attr);
 317
 318 /**
 319  * Send FORGET command
 320  */
 321 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 322                       unsigned long nodeid, u64 nlookup);
 323
 324 /**
 325  * Initialise file operations on a regular file
 326  */
 327 void fuse_init_file_inode(struct inode *inode);
 328
 329 /**
 330  * Initialise inode operations on regular files and special files
 331  */
 332 void fuse_init_common(struct inode *inode);
 333
 334 /**
 335  * Initialise inode and file operations on a directory
 336  */
 337 void fuse_init_dir(struct inode *inode);
 338
 339 /**
 340  * Initialise inode operations on a symlink
 341  */
 342 void fuse_init_symlink(struct inode *inode);
 343
 344 /**
 345  * Change attributes of an inode
 346  */
 347 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
 348
 349 /**
 350  * Check if the connection can be released, and if yes, then free the
 351  * connection structure
 352  */
 353 void fuse_release_conn(struct fuse_conn *fc);
 354
 355 /**
 356  * Initialize the client device
 357  */
 358 int fuse_dev_init(void);
 359
 360 /**
 361  * Cleanup the client device
 362  */
 363 void fuse_dev_cleanup(void);
 364
 365 /**
 366  * Allocate a request
 367  */
 368 struct fuse_req *fuse_request_alloc(void);
 369
 370 /**
 371  * Free a request
 372  */
 373 void fuse_request_free(struct fuse_req *req);
 374
 375 /**
 376  * Reinitialize a request, the preallocated flag is left unmodified
 377  */
 378 void fuse_reset_request(struct fuse_req *req);
 379
 380 /**
 381  * Reserve a preallocated request
 382  */
 383 struct fuse_req *fuse_get_request(struct fuse_conn *fc);
 384
 385 /**
 386  * Reserve a preallocated request, only interruptible by SIGKILL
 387  */
 388 struct fuse_req *fuse_get_request_nonint(struct fuse_conn *fc);
 389
 390 /**
 391  * Decrement reference count of a request.  If count goes to zero put
 392  * on unused list (preallocated) or free reqest (not preallocated).
 393  */
 394 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
 395
 396 /**
 397  * Send a request (synchronous, interruptible)
 398  */
 399 void request_send(struct fuse_conn *fc, struct fuse_req *req);
 400
 401 /**
 402  * Send a request (synchronous, non-interruptible except by SIGKILL)
 403  */
 404 void request_send_nonint(struct fuse_conn *fc, struct fuse_req *req);
 405
 406 /**
 407  * Send a request with no reply
 408  */
 409 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
 410
 411 /**
 412  * Send a request in the background
 413  */
 414 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 415
 416 /**
 417  * Release inodes and file assiciated with background request
 418  */
 419 void fuse_release_background(struct fuse_req *req);
 420
 421 /**
 422  * Get the attributes of a file
 423  */
 424 int fuse_do_getattr(struct inode *inode);
 425
 426 /**
 427  * Invalidate inode attributes
 428  */
 429 void fuse_invalidate_attr(struct inode *inode);
 430
 431 /**
 432  * Send the INIT message
 433  */
 434 void fuse_send_init(struct fuse_conn *fc);