2 FUSE: Filesystem in Userspace
3 Copyright (C) 2001-2005 Miklos Szeredi <miklos@szeredi.hu>
5 This program can be distributed under the terms of the GNU GPL.
9 #include <linux/fuse.h>
11 #include <linux/wait.h>
12 #include <linux/list.h>
13 #include <linux/spinlock.h>
15 #include <linux/backing-dev.h>
16 #include <asm/semaphore.h>
18 /** Max number of pages that can be used in a single read request */
19 #define FUSE_MAX_PAGES_PER_REQ 32
21 /** If more requests are outstanding, then the operation will block */
22 #define FUSE_MAX_OUTSTANDING 10
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)
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)
33 /** If the FUSE_KERNEL_CACHE flag is given, then cached data will not
35 #define FUSE_KERNEL_CACHE (1 << 2)
37 /** Bypass the page cache for read and write operations */
38 #define FUSE_DIRECT_IO (1 << 3)
45 /** Unique ID, which identifies the inode between userspace
49 /** Number of lookups on this inode */
52 /** The request used for sending the FORGET message */
53 struct fuse_req *forget_req;
55 /** Time in jiffies until the file attributes are valid */
59 /** FUSE specific file data */
61 /** Request reserved for flush and release */
62 struct fuse_req *release_req;
64 /** File handle used by userspace */
68 /** One input argument of a request */
74 /** The request input */
76 /** The request header */
77 struct fuse_in_header h;
79 /** True if the data for the last argument is in req->pages */
82 /** Number of arguments */
85 /** Array of arguments */
86 struct fuse_in_arg args[3];
89 /** One output argument of a request */
95 /** The request output */
97 /** Header returned from userspace */
98 struct fuse_out_header h;
100 /** Last argument is variable length (can be shorter than
104 /** Last argument is a list of pages to copy data to */
107 /** Zero partially or not copied pages */
108 unsigned page_zeroing:1;
110 /** Number or arguments */
113 /** Array of arguments */
114 struct fuse_arg args[3];
121 * A request to the client
124 /** This can be on either unused_list, pending or processing
125 lists in fuse_conn */
126 struct list_head list;
128 /** Entry on the background list */
129 struct list_head bg_entry;
134 /** True if the request has reply */
137 /** The request is preallocated */
138 unsigned preallocated:1;
140 /** The request was interrupted */
141 unsigned interrupted:1;
143 /** Request is sent in the background */
144 unsigned background:1;
146 /** Data is being copied to/from the request */
149 /** Request has been sent to userspace */
152 /** The request is finished */
155 /** The request input */
158 /** The request output */
161 /** Used to wake up the task waiting for completion of request*/
162 wait_queue_head_t waitq;
164 /** Data for asynchronous requests */
166 struct fuse_forget_in forget_in;
167 struct fuse_release_in release_in;
168 struct fuse_init_in_out init_in_out;
172 struct page *pages[FUSE_MAX_PAGES_PER_REQ];
174 /** number of pages in vector */
177 /** offset of data on first page */
178 unsigned page_offset;
180 /** Inode used in the request */
183 /** Second inode used in the request (or NULL) */
184 struct inode *inode2;
186 /** File used in the request (or NULL) */
193 * This structure is created, when the filesystem is mounted, and is
194 * destroyed, when the client device is closed and the filesystem is
198 /** Reference count */
201 /** The user id for this mount */
204 /** The group id for this mount */
207 /** The fuse mount flags for this mount */
210 /** Maximum read size */
213 /** Maximum write size */
216 /** Readers of the connection are waiting on this */
217 wait_queue_head_t waitq;
219 /** The list of pending requests */
220 struct list_head pending;
222 /** The list of requests being processed */
223 struct list_head processing;
225 /** Requests put in the background (RELEASE or any other
226 interrupted request) */
227 struct list_head background;
229 /** Controls the maximum number of outstanding requests */
230 struct semaphore outstanding_sem;
232 /** This counts the number of outstanding requests if
233 outstanding_sem would go negative */
234 unsigned outstanding_debt;
236 /** RW semaphore for exclusion with fuse_put_super() */
237 struct rw_semaphore sbput_sem;
239 /** The list of unused requests */
240 struct list_head unused_list;
242 /** The next unique request id */
245 /** Mount is active */
246 unsigned mounted : 1;
248 /** Connection established */
249 unsigned connected : 1;
251 /** Connection failed (version mismatch) */
252 unsigned conn_error : 1;
254 /** Is fsync not implemented by fs? */
255 unsigned no_fsync : 1;
257 /** Is flush not implemented by fs? */
258 unsigned no_flush : 1;
260 /** Is setxattr not implemented by fs? */
261 unsigned no_setxattr : 1;
263 /** Is getxattr not implemented by fs? */
264 unsigned no_getxattr : 1;
266 /** Is listxattr not implemented by fs? */
267 unsigned no_listxattr : 1;
269 /** Is removexattr not implemented by fs? */
270 unsigned no_removexattr : 1;
272 /** Backing dev info */
273 struct backing_dev_info bdi;
276 static inline struct fuse_conn **get_fuse_conn_super_p(struct super_block *sb)
278 return (struct fuse_conn **) &sb->s_fs_info;
281 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
283 return *get_fuse_conn_super_p(sb);
286 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
288 return get_fuse_conn_super(inode->i_sb);
291 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
293 return container_of(inode, struct fuse_inode, inode);
296 static inline u64 get_node_id(struct inode *inode)
298 return get_fuse_inode(inode)->nodeid;
301 /** Device operations */
302 extern struct file_operations fuse_dev_operations;
305 * This is the single global spinlock which protects FUSE's structures
307 * The following data is protected by this lock:
309 * - the private_data field of the device file
310 * - the s_fs_info field of the super block
311 * - unused_list, pending, processing lists in fuse_conn
312 * - background list in fuse_conn
313 * - the unique request ID counter reqctr in fuse_conn
314 * - the sb (super_block) field in fuse_conn
315 * - the file (device file) field in fuse_conn
317 extern spinlock_t fuse_lock;
320 * Get a filled in inode
322 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
323 int generation, struct fuse_attr *attr);
326 * Send FORGET command
328 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
329 unsigned long nodeid, u64 nlookup);
332 * Send READ or READDIR request
334 size_t fuse_send_read_common(struct fuse_req *req, struct file *file,
335 struct inode *inode, loff_t pos, size_t count,
339 * Send OPEN or OPENDIR request
341 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
344 * Send RELEASE or RELEASEDIR request
346 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
349 * Initialise file operations on a regular file
351 void fuse_init_file_inode(struct inode *inode);
354 * Initialise inode operations on regular files and special files
356 void fuse_init_common(struct inode *inode);
359 * Initialise inode and file operations on a directory
361 void fuse_init_dir(struct inode *inode);
364 * Initialise inode operations on a symlink
366 void fuse_init_symlink(struct inode *inode);
369 * Change attributes of an inode
371 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
374 * Check if the connection can be released, and if yes, then free the
375 * connection structure
377 void fuse_release_conn(struct fuse_conn *fc);
380 * Initialize the client device
382 int fuse_dev_init(void);
385 * Cleanup the client device
387 void fuse_dev_cleanup(void);
392 struct fuse_req *fuse_request_alloc(void);
397 void fuse_request_free(struct fuse_req *req);
400 * Reinitialize a request, the preallocated flag is left unmodified
402 void fuse_reset_request(struct fuse_req *req);
405 * Reserve a preallocated request
407 struct fuse_req *fuse_get_request(struct fuse_conn *fc);
410 * Reserve a preallocated request, only interruptible by SIGKILL
412 struct fuse_req *fuse_get_request_nonint(struct fuse_conn *fc);
415 * Decrement reference count of a request. If count goes to zero put
416 * on unused list (preallocated) or free reqest (not preallocated).
418 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
421 * Send a request (synchronous, interruptible)
423 void request_send(struct fuse_conn *fc, struct fuse_req *req);
426 * Send a request (synchronous, non-interruptible except by SIGKILL)
428 void request_send_nonint(struct fuse_conn *fc, struct fuse_req *req);
431 * Send a request with no reply
433 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
436 * Send a request in the background
438 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
441 * Release inodes and file assiciated with background request
443 void fuse_release_background(struct fuse_req *req);
446 * Get the attributes of a file
448 int fuse_do_getattr(struct inode *inode);
451 * Invalidate inode attributes
453 void fuse_invalidate_attr(struct inode *inode);
456 * Send the INIT message
458 void fuse_send_init(struct fuse_conn *fc);