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 /** FUSE inode */
  25 struct fuse_inode {
  26         /** Inode data */
  27         struct inode inode;
  28
  29         /** Unique ID, which identifies the inode between userspace
  30          * and kernel */
  31         u64 nodeid;
  32
  33         /** Number of lookups on this inode */
  34         u64 nlookup;
  35
  36         /** The request used for sending the FORGET message */
  37         struct fuse_req *forget_req;
  38
  39         /** Time in jiffies until the file attributes are valid */
  40         unsigned long i_time;
  41 };
  42
  43 /** FUSE specific file data */
  44 struct fuse_file {
  45         /** Request reserved for flush and release */
  46         struct fuse_req *release_req;
  47
  48         /** File handle used by userspace */
  49         u64 fh;
  50 };
  51
  52 /** One input argument of a request */
  53 struct fuse_in_arg {
  54         unsigned size;
  55         const void *value;
  56 };
  57
  58 /** The request input */
  59 struct fuse_in {
  60         /** The request header */
  61         struct fuse_in_header h;
  62
  63         /** True if the data for the last argument is in req->pages */
  64         unsigned argpages:1;
  65
  66         /** Number of arguments */
  67         unsigned numargs;
  68
  69         /** Array of arguments */
  70         struct fuse_in_arg args[3];
  71 };
  72
  73 /** One output argument of a request */
  74 struct fuse_arg {
  75         unsigned size;
  76         void *value;
  77 };
  78
  79 /** The request output */
  80 struct fuse_out {
  81         /** Header returned from userspace */
  82         struct fuse_out_header h;
  83
  84         /** Last argument is variable length (can be shorter than
  85             arg->size) */
  86         unsigned argvar:1;
  87
  88         /** Last argument is a list of pages to copy data to */
  89         unsigned argpages:1;
  90
  91         /** Zero partially or not copied pages */
  92         unsigned page_zeroing:1;
  93
  94         /** Number or arguments */
  95         unsigned numargs;
  96
  97         /** Array of arguments */
  98         struct fuse_arg args[3];
  99 };
 100
 101 struct fuse_req;
 102 struct fuse_conn;
 103
 104 /**
 105  * A request to the client
 106  */
 107 struct fuse_req {
 108         /** This can be on either unused_list, pending or processing
 109             lists in fuse_conn */
 110         struct list_head list;
 111
 112         /** refcount */
 113         atomic_t count;
 114
 115         /** True if the request has reply */
 116         unsigned isreply:1;
 117
 118         /** The request is preallocated */
 119         unsigned preallocated:1;
 120
 121         /** The request was interrupted */
 122         unsigned interrupted:1;
 123
 124         /** Request is sent in the background */
 125         unsigned background:1;
 126
 127         /** Data is being copied to/from the request */
 128         unsigned locked:1;
 129
 130         /** Request has been sent to userspace */
 131         unsigned sent:1;
 132
 133         /** The request is finished */
 134         unsigned finished:1;
 135
 136         /** The request input */
 137         struct fuse_in in;
 138
 139         /** The request output */
 140         struct fuse_out out;
 141
 142         /** Used to wake up the task waiting for completion of request*/
 143         wait_queue_head_t waitq;
 144
 145         /** Data for asynchronous requests */
 146         union {
 147                 struct fuse_forget_in forget_in;
 148                 struct fuse_release_in release_in;
 149                 struct fuse_init_in_out init_in_out;
 150         } misc;
 151
 152         /** page vector */
 153         struct page *pages[FUSE_MAX_PAGES_PER_REQ];
 154
 155         /** number of pages in vector */
 156         unsigned num_pages;
 157
 158         /** offset of data on first page */
 159         unsigned page_offset;
 160
 161         /** Inode used in the request */
 162         struct inode *inode;
 163
 164         /** Second inode used in the request (or NULL) */
 165         struct inode *inode2;
 166
 167         /** File used in the request (or NULL) */
 168         struct file *file;
 169 };
 170
 171 /**
 172  * A Fuse connection.
 173  *
 174  * This structure is created, when the filesystem is mounted, and is
 175  * destroyed, when the client device is closed and the filesystem is
 176  * unmounted.
 177  */
 178 struct fuse_conn {
 179         /** The superblock of the mounted filesystem */
 180         struct super_block *sb;
 181
 182         /** The opened client device */
 183         struct file *file;
 184
 185         /** The user id for this mount */
 186         uid_t user_id;
 187
 188         /** Readers of the connection are waiting on this */
 189         wait_queue_head_t waitq;
 190
 191         /** The list of pending requests */
 192         struct list_head pending;
 193
 194         /** The list of requests being processed */
 195         struct list_head processing;
 196
 197         /** Controls the maximum number of outstanding requests */
 198         struct semaphore outstanding_sem;
 199
 200         /** This counts the number of outstanding requests if
 201             outstanding_sem would go negative */
 202         unsigned outstanding_debt;
 203
 204         /** The list of unused requests */
 205         struct list_head unused_list;
 206
 207         /** The next unique request id */
 208         u64 reqctr;
 209
 210         /** Connection failed (version mismatch) */
 211         unsigned conn_error : 1;
 212
 213         /** Is fsync not implemented by fs? */
 214         unsigned no_fsync : 1;
 215
 216         /** Is flush not implemented by fs? */
 217         unsigned no_flush : 1;
 218
 219         /** Backing dev info */
 220         struct backing_dev_info bdi;
 221 };
 222
 223 struct fuse_getdir_out_i {
 224         int fd;
 225         void *file; /* Used by kernel only */
 226 };
 227
 228 static inline struct fuse_conn **get_fuse_conn_super_p(struct super_block *sb)
 229 {
 230         return (struct fuse_conn **) &sb->s_fs_info;
 231 }
 232
 233 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 234 {
 235         return *get_fuse_conn_super_p(sb);
 236 }
 237
 238 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 239 {
 240         return get_fuse_conn_super(inode->i_sb);
 241 }
 242
 243 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 244 {
 245         return container_of(inode, struct fuse_inode, inode);
 246 }
 247
 248 static inline u64 get_node_id(struct inode *inode)
 249 {
 250         return get_fuse_inode(inode)->nodeid;
 251 }
 252
 253 /** Device operations */
 254 extern struct file_operations fuse_dev_operations;
 255
 256 /**
 257  * This is the single global spinlock which protects FUSE's structures
 258  *
 259  * The following data is protected by this lock:
 260  *
 261  *  - the private_data field of the device file
 262  *  - the s_fs_info field of the super block
 263  *  - unused_list, pending, processing lists in fuse_conn
 264  *  - the unique request ID counter reqctr in fuse_conn
 265  *  - the sb (super_block) field in fuse_conn
 266  *  - the file (device file) field in fuse_conn
 267  */
 268 extern spinlock_t fuse_lock;
 269
 270 /**
 271  * Get a filled in inode
 272  */
 273 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 274                         int generation, struct fuse_attr *attr);
 275
 276 /**
 277  * Send FORGET command
 278  */
 279 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 280                       unsigned long nodeid, u64 nlookup);
 281
 282 /**
 283  * Initialise file operations on a regular file
 284  */
 285 void fuse_init_file_inode(struct inode *inode);
 286
 287 /**
 288  * Initialise inode operations on regular files and special files
 289  */
 290 void fuse_init_common(struct inode *inode);
 291
 292 /**
 293  * Initialise inode and file operations on a directory
 294  */
 295 void fuse_init_dir(struct inode *inode);
 296
 297 /**
 298  * Initialise inode operations on a symlink
 299  */
 300 void fuse_init_symlink(struct inode *inode);
 301
 302 /**
 303  * Change attributes of an inode
 304  */
 305 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
 306
 307 /**
 308  * Check if the connection can be released, and if yes, then free the
 309  * connection structure
 310  */
 311 void fuse_release_conn(struct fuse_conn *fc);
 312
 313 /**
 314  * Initialize the client device
 315  */
 316 int fuse_dev_init(void);
 317
 318 /**
 319  * Cleanup the client device
 320  */
 321 void fuse_dev_cleanup(void);
 322
 323 /**
 324  * Allocate a request
 325  */
 326 struct fuse_req *fuse_request_alloc(void);
 327
 328 /**
 329  * Free a request
 330  */
 331 void fuse_request_free(struct fuse_req *req);
 332
 333 /**
 334  * Reinitialize a request, the preallocated flag is left unmodified
 335  */
 336 void fuse_reset_request(struct fuse_req *req);
 337
 338 /**
 339  * Reserve a preallocated request
 340  */
 341 struct fuse_req *fuse_get_request(struct fuse_conn *fc);
 342
 343 /**
 344  * Reserve a preallocated request, only interruptible by SIGKILL
 345  */
 346 struct fuse_req *fuse_get_request_nonint(struct fuse_conn *fc);
 347
 348 /**
 349  * Decrement reference count of a request.  If count goes to zero put
 350  * on unused list (preallocated) or free reqest (not preallocated).
 351  */
 352 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
 353
 354 /**
 355  * Send a request (synchronous, interruptible)
 356  */
 357 void request_send(struct fuse_conn *fc, struct fuse_req *req);
 358
 359 /**
 360  * Send a request (synchronous, non-interruptible except by SIGKILL)
 361  */
 362 void request_send_nonint(struct fuse_conn *fc, struct fuse_req *req);
 363
 364 /**
 365  * Send a request with no reply
 366  */
 367 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
 368
 369 /**
 370  * Send a request in the background
 371  */
 372 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 373
 374 /**
 375  * Get the attributes of a file
 376  */
 377 int fuse_do_getattr(struct inode *inode);
 378
 379 /**
 380  * Invalidate inode attributes
 381  */
 382 void fuse_invalidate_attr(struct inode *inode);
 383
 384 /**
 385  * Send the INIT message
 386  */
 387 void fuse_send_init(struct fuse_conn *fc);