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d8a5ba45 MS |
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 | ||
334f485d MS |
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 | ||
d8a5ba45 MS |
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 | /** Time in jiffies until the file attributes are valid */ | |
34 | unsigned long i_time; | |
35 | }; | |
36 | ||
334f485d MS |
37 | /** One input argument of a request */ |
38 | struct fuse_in_arg { | |
39 | unsigned size; | |
40 | const void *value; | |
41 | }; | |
42 | ||
43 | /** The request input */ | |
44 | struct fuse_in { | |
45 | /** The request header */ | |
46 | struct fuse_in_header h; | |
47 | ||
48 | /** True if the data for the last argument is in req->pages */ | |
49 | unsigned argpages:1; | |
50 | ||
51 | /** Number of arguments */ | |
52 | unsigned numargs; | |
53 | ||
54 | /** Array of arguments */ | |
55 | struct fuse_in_arg args[3]; | |
56 | }; | |
57 | ||
58 | /** One output argument of a request */ | |
59 | struct fuse_arg { | |
60 | unsigned size; | |
61 | void *value; | |
62 | }; | |
63 | ||
64 | /** The request output */ | |
65 | struct fuse_out { | |
66 | /** Header returned from userspace */ | |
67 | struct fuse_out_header h; | |
68 | ||
69 | /** Last argument is variable length (can be shorter than | |
70 | arg->size) */ | |
71 | unsigned argvar:1; | |
72 | ||
73 | /** Last argument is a list of pages to copy data to */ | |
74 | unsigned argpages:1; | |
75 | ||
76 | /** Zero partially or not copied pages */ | |
77 | unsigned page_zeroing:1; | |
78 | ||
79 | /** Number or arguments */ | |
80 | unsigned numargs; | |
81 | ||
82 | /** Array of arguments */ | |
83 | struct fuse_arg args[3]; | |
84 | }; | |
85 | ||
86 | struct fuse_req; | |
87 | struct fuse_conn; | |
88 | ||
89 | /** | |
90 | * A request to the client | |
91 | */ | |
92 | struct fuse_req { | |
93 | /** This can be on either unused_list, pending or processing | |
94 | lists in fuse_conn */ | |
95 | struct list_head list; | |
96 | ||
97 | /** refcount */ | |
98 | atomic_t count; | |
99 | ||
100 | /** True if the request has reply */ | |
101 | unsigned isreply:1; | |
102 | ||
103 | /** The request is preallocated */ | |
104 | unsigned preallocated:1; | |
105 | ||
106 | /** The request was interrupted */ | |
107 | unsigned interrupted:1; | |
108 | ||
109 | /** Request is sent in the background */ | |
110 | unsigned background:1; | |
111 | ||
112 | /** Data is being copied to/from the request */ | |
113 | unsigned locked:1; | |
114 | ||
115 | /** Request has been sent to userspace */ | |
116 | unsigned sent:1; | |
117 | ||
118 | /** The request is finished */ | |
119 | unsigned finished:1; | |
120 | ||
121 | /** The request input */ | |
122 | struct fuse_in in; | |
123 | ||
124 | /** The request output */ | |
125 | struct fuse_out out; | |
126 | ||
127 | /** Used to wake up the task waiting for completion of request*/ | |
128 | wait_queue_head_t waitq; | |
129 | ||
130 | /** Data for asynchronous requests */ | |
131 | union { | |
132 | struct fuse_init_in_out init_in_out; | |
133 | } misc; | |
134 | ||
135 | /** page vector */ | |
136 | struct page *pages[FUSE_MAX_PAGES_PER_REQ]; | |
137 | ||
138 | /** number of pages in vector */ | |
139 | unsigned num_pages; | |
140 | ||
141 | /** offset of data on first page */ | |
142 | unsigned page_offset; | |
143 | ||
144 | /** Inode used in the request */ | |
145 | struct inode *inode; | |
146 | ||
147 | /** Second inode used in the request (or NULL) */ | |
148 | struct inode *inode2; | |
149 | ||
150 | /** File used in the request (or NULL) */ | |
151 | struct file *file; | |
152 | }; | |
153 | ||
d8a5ba45 MS |
154 | /** |
155 | * A Fuse connection. | |
156 | * | |
157 | * This structure is created, when the filesystem is mounted, and is | |
158 | * destroyed, when the client device is closed and the filesystem is | |
159 | * unmounted. | |
160 | */ | |
161 | struct fuse_conn { | |
162 | /** The superblock of the mounted filesystem */ | |
163 | struct super_block *sb; | |
164 | ||
334f485d MS |
165 | /** The opened client device */ |
166 | struct file *file; | |
167 | ||
d8a5ba45 MS |
168 | /** The user id for this mount */ |
169 | uid_t user_id; | |
170 | ||
334f485d MS |
171 | /** Readers of the connection are waiting on this */ |
172 | wait_queue_head_t waitq; | |
173 | ||
174 | /** The list of pending requests */ | |
175 | struct list_head pending; | |
176 | ||
177 | /** The list of requests being processed */ | |
178 | struct list_head processing; | |
179 | ||
180 | /** Controls the maximum number of outstanding requests */ | |
181 | struct semaphore outstanding_sem; | |
182 | ||
183 | /** This counts the number of outstanding requests if | |
184 | outstanding_sem would go negative */ | |
185 | unsigned outstanding_debt; | |
186 | ||
187 | /** The list of unused requests */ | |
188 | struct list_head unused_list; | |
189 | ||
190 | /** The next unique request id */ | |
191 | u64 reqctr; | |
192 | ||
193 | /** Connection failed (version mismatch) */ | |
194 | unsigned conn_error : 1; | |
195 | ||
d8a5ba45 MS |
196 | /** Backing dev info */ |
197 | struct backing_dev_info bdi; | |
198 | }; | |
199 | ||
200 | static inline struct fuse_conn **get_fuse_conn_super_p(struct super_block *sb) | |
201 | { | |
202 | return (struct fuse_conn **) &sb->s_fs_info; | |
203 | } | |
204 | ||
205 | static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb) | |
206 | { | |
207 | return *get_fuse_conn_super_p(sb); | |
208 | } | |
209 | ||
210 | static inline struct fuse_conn *get_fuse_conn(struct inode *inode) | |
211 | { | |
212 | return get_fuse_conn_super(inode->i_sb); | |
213 | } | |
214 | ||
215 | static inline struct fuse_inode *get_fuse_inode(struct inode *inode) | |
216 | { | |
217 | return container_of(inode, struct fuse_inode, inode); | |
218 | } | |
219 | ||
220 | static inline u64 get_node_id(struct inode *inode) | |
221 | { | |
222 | return get_fuse_inode(inode)->nodeid; | |
223 | } | |
224 | ||
334f485d MS |
225 | /** Device operations */ |
226 | extern struct file_operations fuse_dev_operations; | |
227 | ||
d8a5ba45 MS |
228 | /** |
229 | * This is the single global spinlock which protects FUSE's structures | |
230 | * | |
231 | * The following data is protected by this lock: | |
232 | * | |
334f485d | 233 | * - the private_data field of the device file |
d8a5ba45 | 234 | * - the s_fs_info field of the super block |
334f485d MS |
235 | * - unused_list, pending, processing lists in fuse_conn |
236 | * - the unique request ID counter reqctr in fuse_conn | |
d8a5ba45 | 237 | * - the sb (super_block) field in fuse_conn |
334f485d | 238 | * - the file (device file) field in fuse_conn |
d8a5ba45 MS |
239 | */ |
240 | extern spinlock_t fuse_lock; | |
241 | ||
242 | /** | |
243 | * Check if the connection can be released, and if yes, then free the | |
244 | * connection structure | |
245 | */ | |
246 | void fuse_release_conn(struct fuse_conn *fc); | |
247 | ||
334f485d MS |
248 | /** |
249 | * Initialize the client device | |
250 | */ | |
251 | int fuse_dev_init(void); | |
252 | ||
253 | /** | |
254 | * Cleanup the client device | |
255 | */ | |
256 | void fuse_dev_cleanup(void); | |
257 | ||
258 | /** | |
259 | * Allocate a request | |
260 | */ | |
261 | struct fuse_req *fuse_request_alloc(void); | |
262 | ||
263 | /** | |
264 | * Free a request | |
265 | */ | |
266 | void fuse_request_free(struct fuse_req *req); | |
267 | ||
268 | /** | |
269 | * Reinitialize a request, the preallocated flag is left unmodified | |
270 | */ | |
271 | void fuse_reset_request(struct fuse_req *req); | |
272 | ||
273 | /** | |
274 | * Reserve a preallocated request | |
275 | */ | |
276 | struct fuse_req *fuse_get_request(struct fuse_conn *fc); | |
277 | ||
278 | /** | |
279 | * Reserve a preallocated request, only interruptible by SIGKILL | |
280 | */ | |
281 | struct fuse_req *fuse_get_request_nonint(struct fuse_conn *fc); | |
282 | ||
283 | /** | |
284 | * Decrement reference count of a request. If count goes to zero put | |
285 | * on unused list (preallocated) or free reqest (not preallocated). | |
286 | */ | |
287 | void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req); | |
288 | ||
289 | /** | |
290 | * Send a request (synchronous, interruptible) | |
291 | */ | |
292 | void request_send(struct fuse_conn *fc, struct fuse_req *req); | |
293 | ||
294 | /** | |
295 | * Send a request (synchronous, non-interruptible except by SIGKILL) | |
296 | */ | |
297 | void request_send_nonint(struct fuse_conn *fc, struct fuse_req *req); | |
298 | ||
299 | /** | |
300 | * Send a request with no reply | |
301 | */ | |
302 | void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req); | |
303 | ||
304 | /** | |
305 | * Send a request in the background | |
306 | */ | |
307 | void request_send_background(struct fuse_conn *fc, struct fuse_req *req); | |
308 | ||
309 | /** | |
310 | * Send the INIT message | |
311 | */ | |
312 | void fuse_send_init(struct fuse_conn *fc); |