1 /*
2 FUSE: Filesystem in Userspace
3 Copyright (C) 2001-2006 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/mount.h>
12 #include <linux/wait.h>
13 #include <linux/list.h>
14 #include <linux/spinlock.h>
15 #include <linux/mm.h>
16 #include <linux/backing-dev.h>
17 #include <linux/mutex.h>
18
19 /** Max number of pages that can be used in a single read request */
20 #define FUSE_MAX_PAGES_PER_REQ 32
21
22 /** Maximum number of outstanding background requests */
23 #define FUSE_MAX_BACKGROUND 12
24
25 /** Congestion starts at 75% of maximum */
26 #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100)
27
28 /** It could be as large as PATH_MAX, but would that have any uses? */
29 #define FUSE_NAME_MAX 1024
30
31 /** Number of dentries for each connection in the control filesystem */
32 #define FUSE_CTL_NUM_DENTRIES 3
33
34 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
35 module will check permissions based on the file mode. Otherwise no
36 permission checking is done in the kernel */
37 #define FUSE_DEFAULT_PERMISSIONS (1 << 0)
38
39 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user
40 doing the mount will be allowed to access the filesystem */
41 #define FUSE_ALLOW_OTHER (1 << 1)
42
43 /** List of active connections */
44 extern struct list_head fuse_conn_list;
45
46 /** Global mutex protecting fuse_conn_list and the control filesystem */
47 extern struct mutex fuse_mutex;
48
49 /** FUSE inode */
50 struct fuse_inode {
51 /** Inode data */
52 struct inode inode;
53
54 /** Unique ID, which identifies the inode between userspace
55 * and kernel */
56 u64 nodeid;
57
58 /** Number of lookups on this inode */
59 u64 nlookup;
60
61 /** The request used for sending the FORGET message */
62 struct fuse_req *forget_req;
63
64 /** Time in jiffies until the file attributes are valid */
65 u64 i_time;
66
67 /** The sticky bit in inode->i_mode may have been removed, so
68 preserve the original mode */
69 mode_t orig_i_mode;
70
71 /** Version of last attribute change */
72 u64 attr_version;
73
74 /** Files usable in writepage. Protected by fc->lock */
75 struct list_head write_files;
76 };
77
78 /** FUSE specific file data */
79 struct fuse_file {
80 /** Request reserved for flush and release */
81 struct fuse_req *reserved_req;
82
83 /** File handle used by userspace */
84 u64 fh;
85
86 /** Refcount */
87 atomic_t count;
88
89 /** Entry on inode's write_files list */
90 struct list_head write_entry;
91 };
92
93 /** One input argument of a request */
94 struct fuse_in_arg {
95 unsigned size;
96 const void *value;
97 };
98
99 /** The request input */
100 struct fuse_in {
101 /** The request header */
102 struct fuse_in_header h;
103
104 /** True if the data for the last argument is in req->pages */
105 unsigned argpages:1;
106
107 /** Number of arguments */
108 unsigned numargs;
109
110 /** Array of arguments */
111 struct fuse_in_arg args[3];
112 };
113
114 /** One output argument of a request */
115 struct fuse_arg {
116 unsigned size;
117 void *value;
118 };
119
120 /** The request output */
121 struct fuse_out {
122 /** Header returned from userspace */
123 struct fuse_out_header h;
124
125 /*
126 * The following bitfields are not changed during the request
127 * processing
128 */
129
130 /** Last argument is variable length (can be shorter than
131 arg->size) */
132 unsigned argvar:1;
133
134 /** Last argument is a list of pages to copy data to */
135 unsigned argpages:1;
136
137 /** Zero partially or not copied pages */
138 unsigned page_zeroing:1;
139
140 /** Number or arguments */
141 unsigned numargs;
142
143 /** Array of arguments */
144 struct fuse_arg args[3];
145 };
146
147 /** The request state */
148 enum fuse_req_state {
149 FUSE_REQ_INIT = 0,
150 FUSE_REQ_PENDING,
151 FUSE_REQ_READING,
152 FUSE_REQ_SENT,
153 FUSE_REQ_WRITING,
154 FUSE_REQ_FINISHED
155 };
156
157 struct fuse_conn;
158
159 /**
160 * A request to the client
161 */
162 struct fuse_req {
163 /** This can be on either pending processing or io lists in
164 fuse_conn */
165 struct list_head list;
166
167 /** Entry on the interrupts list */
168 struct list_head intr_entry;
169
170 /** refcount */
171 atomic_t count;
172
173 /** Unique ID for the interrupt request */
174 u64 intr_unique;
175
176 /*
177 * The following bitfields are either set once before the
178 * request is queued or setting/clearing them is protected by
179 * fuse_conn->lock
180 */
181
182 /** True if the request has reply */
183 unsigned isreply:1;
184
185 /** Force sending of the request even if interrupted */
186 unsigned force:1;
187
188 /** The request was aborted */
189 unsigned aborted:1;
190
191 /** Request is sent in the background */
192 unsigned background:1;
193
194 /** The request has been interrupted */
195 unsigned interrupted:1;
196
197 /** Data is being copied to/from the request */
198 unsigned locked:1;
199
200 /** Request is counted as "waiting" */
201 unsigned waiting:1;
202
203 /** State of the request */
204 enum fuse_req_state state;
205
206 /** The request input */
207 struct fuse_in in;
208
209 /** The request output */
210 struct fuse_out out;
211
212 /** Used to wake up the task waiting for completion of request*/
213 wait_queue_head_t waitq;
214
215 /** Data for asynchronous requests */
216 union {
217 struct fuse_forget_in forget_in;
218 struct {
219 struct fuse_release_in in;
220 struct vfsmount *vfsmount;
221 struct dentry *dentry;
222 } release;
223 struct fuse_init_in init_in;
224 struct fuse_init_out init_out;
225 struct fuse_read_in read_in;
226 struct {
227 struct fuse_write_in in;
228 struct fuse_write_out out;
229 } write;
230 struct fuse_lk_in lk_in;
231 } misc;
232
233 /** page vector */
234 struct page *pages[FUSE_MAX_PAGES_PER_REQ];
235
236 /** number of pages in vector */
237 unsigned num_pages;
238
239 /** offset of data on first page */
240 unsigned page_offset;
241
242 /** File used in the request (or NULL) */
243 struct fuse_file *ff;
244
245 /** Request completion callback */
246 void (*end)(struct fuse_conn *, struct fuse_req *);
247
248 /** Request is stolen from fuse_file->reserved_req */
249 struct file *stolen_file;
250 };
251
252 /**
253 * A Fuse connection.
254 *
255 * This structure is created, when the filesystem is mounted, and is
256 * destroyed, when the client device is closed and the filesystem is
257 * unmounted.
258 */
259 struct fuse_conn {
260 /** Lock protecting accessess to members of this structure */
261 spinlock_t lock;
262
263 /** Mutex protecting against directory alias creation */
264 struct mutex inst_mutex;
265
266 /** Refcount */
267 atomic_t count;
268
269 /** The user id for this mount */
270 uid_t user_id;
271
272 /** The group id for this mount */
273 gid_t group_id;
274
275 /** The fuse mount flags for this mount */
276 unsigned flags;
277
278 /** Maximum read size */
279 unsigned max_read;
280
281 /** Maximum write size */
282 unsigned max_write;
283
284 /** Readers of the connection are waiting on this */
285 wait_queue_head_t waitq;
286
287 /** The list of pending requests */
288 struct list_head pending;
289
290 /** The list of requests being processed */
291 struct list_head processing;
292
293 /** The list of requests under I/O */
294 struct list_head io;
295
296 /** Number of requests currently in the background */
297 unsigned num_background;
298
299 /** Number of background requests currently queued for userspace */
300 unsigned active_background;
301
302 /** The list of background requests set aside for later queuing */
303 struct list_head bg_queue;
304
305 /** Pending interrupts */
306 struct list_head interrupts;
307
308 /** Flag indicating if connection is blocked. This will be
309 the case before the INIT reply is received, and if there
310 are too many outstading backgrounds requests */
311 int blocked;
312
313 /** waitq for blocked connection */
314 wait_queue_head_t blocked_waitq;
315
316 /** waitq for reserved requests */
317 wait_queue_head_t reserved_req_waitq;
318
319 /** The next unique request id */
320 u64 reqctr;
321
322 /** Connection established, cleared on umount, connection
323 abort and device release */
324 unsigned connected;
325
326 /** Connection failed (version mismatch). Cannot race with
327 setting other bitfields since it is only set once in INIT
328 reply, before any other request, and never cleared */
329 unsigned conn_error : 1;
330
331 /** Connection successful. Only set in INIT */
332 unsigned conn_init : 1;
333
334 /** Do readpages asynchronously? Only set in INIT */
335 unsigned async_read : 1;
336
337 /** Do not send separate SETATTR request before open(O_TRUNC) */
338 unsigned atomic_o_trunc : 1;
339
340 /*
341 * The following bitfields are only for optimization purposes
342 * and hence races in setting them will not cause malfunction
343 */
344
345 /** Is fsync not implemented by fs? */
346 unsigned no_fsync : 1;
347
348 /** Is fsyncdir not implemented by fs? */
349 unsigned no_fsyncdir : 1;
350
351 /** Is flush not implemented by fs? */
352 unsigned no_flush : 1;
353
354 /** Is setxattr not implemented by fs? */
355 unsigned no_setxattr : 1;
356
357 /** Is getxattr not implemented by fs? */
358 unsigned no_getxattr : 1;
359
360 /** Is listxattr not implemented by fs? */
361 unsigned no_listxattr : 1;
362
363 /** Is removexattr not implemented by fs? */
364 unsigned no_removexattr : 1;
365
366 /** Are file locking primitives not implemented by fs? */
367 unsigned no_lock : 1;
368
369 /** Is access not implemented by fs? */
370 unsigned no_access : 1;
371
372 /** Is create not implemented by fs? */
373 unsigned no_create : 1;
374
375 /** Is interrupt not implemented by fs? */
376 unsigned no_interrupt : 1;
377
378 /** Is bmap not implemented by fs? */
379 unsigned no_bmap : 1;
380
381 /** The number of requests waiting for completion */
382 atomic_t num_waiting;
383
384 /** Negotiated minor version */
385 unsigned minor;
386
387 /** Backing dev info */
388 struct backing_dev_info bdi;
389
390 /** Entry on the fuse_conn_list */
391 struct list_head entry;
392
393 /** Unique ID */
394 u64 id;
395
396 /** Dentries in the control filesystem */
397 struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
398
399 /** number of dentries used in the above array */
400 int ctl_ndents;
401
402 /** O_ASYNC requests */
403 struct fasync_struct *fasync;
404
405 /** Key for lock owner ID scrambling */
406 u32 scramble_key[4];
407
408 /** Reserved request for the DESTROY message */
409 struct fuse_req *destroy_req;
410
411 /** Version counter for attribute changes */
412 u64 attr_version;
413 };
414
415 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
416 {
417 return sb->s_fs_info;
418 }
419
420 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
421 {
422 return get_fuse_conn_super(inode->i_sb);
423 }
424
425 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
426 {
427 return container_of(inode, struct fuse_inode, inode);
428 }
429
430 static inline u64 get_node_id(struct inode *inode)
431 {
432 return get_fuse_inode(inode)->nodeid;
433 }
434
435 /** Device operations */
436 extern const struct file_operations fuse_dev_operations;
437
438 /**
439 * Get a filled in inode
440 */
441 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
442 int generation, struct fuse_attr *attr,
443 u64 attr_valid, u64 attr_version);
444
445 /**
446 * Send FORGET command
447 */
448 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
449 unsigned long nodeid, u64 nlookup);
450
451 /**
452 * Initialize READ or READDIR request
453 */
454 void fuse_read_fill(struct fuse_req *req, struct file *file,
455 struct inode *inode, loff_t pos, size_t count, int opcode);
456
457 /**
458 * Send OPEN or OPENDIR request
459 */
460 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
461
462 struct fuse_file *fuse_file_alloc(void);
463 void fuse_file_free(struct fuse_file *ff);
464 void fuse_finish_open(struct inode *inode, struct file *file,
465 struct fuse_file *ff, struct fuse_open_out *outarg);
466
467 /** Fill in ff->reserved_req with a RELEASE request */
468 void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode);
469
470 /**
471 * Send RELEASE or RELEASEDIR request
472 */
473 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
474
475 /**
476 * Send FSYNC or FSYNCDIR request
477 */
478 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
479 int isdir);
480
481 /**
482 * Initialize file operations on a regular file
483 */
484 void fuse_init_file_inode(struct inode *inode);
485
486 /**
487 * Initialize inode operations on regular files and special files
488 */
489 void fuse_init_common(struct inode *inode);
490
491 /**
492 * Initialize inode and file operations on a directory
493 */
494 void fuse_init_dir(struct inode *inode);
495
496 /**
497 * Initialize inode operations on a symlink
498 */
499 void fuse_init_symlink(struct inode *inode);
500
501 /**
502 * Change attributes of an inode
503 */
504 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
505 u64 attr_valid, u64 attr_version);
506
507 /**
508 * Initialize the client device
509 */
510 int fuse_dev_init(void);
511
512 /**
513 * Cleanup the client device
514 */
515 void fuse_dev_cleanup(void);
516
517 int fuse_ctl_init(void);
518 void fuse_ctl_cleanup(void);
519
520 /**
521 * Allocate a request
522 */
523 struct fuse_req *fuse_request_alloc(void);
524
525 /**
526 * Free a request
527 */
528 void fuse_request_free(struct fuse_req *req);
529
530 /**
531 * Get a request, may fail with -ENOMEM
532 */
533 struct fuse_req *fuse_get_req(struct fuse_conn *fc);
534
535 /**
536 * Gets a requests for a file operation, always succeeds
537 */
538 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
539
540 /**
541 * Decrement reference count of a request. If count goes to zero free
542 * the request.
543 */
544 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
545
546 /**
547 * Send a request (synchronous)
548 */
549 void request_send(struct fuse_conn *fc, struct fuse_req *req);
550
551 /**
552 * Send a request with no reply
553 */
554 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
555
556 /**
557 * Send a request in the background
558 */
559 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
560
561 /* Abort all requests */
562 void fuse_abort_conn(struct fuse_conn *fc);
563
564 /**
565 * Invalidate inode attributes
566 */
567 void fuse_invalidate_attr(struct inode *inode);
568
569 /**
570 * Acquire reference to fuse_conn
571 */
572 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
573
574 /**
575 * Release reference to fuse_conn
576 */
577 void fuse_conn_put(struct fuse_conn *fc);
578
579 /**
580 * Add connection to control filesystem
581 */
582 int fuse_ctl_add_conn(struct fuse_conn *fc);
583
584 /**
585 * Remove connection from control filesystem
586 */
587 void fuse_ctl_remove_conn(struct fuse_conn *fc);
588
589 /**
590 * Is file type valid?
591 */
592 int fuse_valid_type(int m);
593
594 /**
595 * Is task allowed to perform filesystem operation?
596 */
597 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
598
599 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
600
601 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
602 struct file *file, bool *refreshed);
603
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