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