xref: /openbmc/linux/fs/fuse/fuse_i.h (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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  * Initialize file operations on a regular file
353  */
354 void fuse_init_file_inode(struct inode *inode);
355 
356 /**
357  * Initialize inode operations on regular files and special files
358  */
359 void fuse_init_common(struct inode *inode);
360 
361 /**
362  * Initialize inode and file operations on a directory
363  */
364 void fuse_init_dir(struct inode *inode);
365 
366 /**
367  * Initialize 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 request (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 associated 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);
452