2 FUSE: Filesystem in Userspace
3 Copyright (C) 2001-2006 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/mount.h>
12 #include <linux/wait.h>
13 #include <linux/list.h>
14 #include <linux/spinlock.h>
16 #include <linux/backing-dev.h>
17 #include <linux/mutex.h>
19 /** Max number of pages that can be used in a single read request */
20 #define FUSE_MAX_PAGES_PER_REQ 32
22 /** Maximum number of outstanding background requests */
23 #define FUSE_MAX_BACKGROUND 12
25 /** Congestion starts at 75% of maximum */
26 #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100)
28 /** It could be as large as PATH_MAX, but would that have any uses? */
29 #define FUSE_NAME_MAX 1024
31 /** Number of dentries for each connection in the control filesystem */
32 #define FUSE_CTL_NUM_DENTRIES 3
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)
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)
43 /** List of active connections */
44 extern struct list_head fuse_conn_list
;
46 /** Global mutex protecting fuse_conn_list and the control filesystem */
47 extern struct mutex fuse_mutex
;
54 /** Unique ID, which identifies the inode between userspace
58 /** Number of lookups on this inode */
61 /** The request used for sending the FORGET message */
62 struct fuse_req
*forget_req
;
64 /** Time in jiffies until the file attributes are valid */
67 /** The sticky bit in inode->i_mode may have been removed, so
68 preserve the original mode */
71 /** Version of last attribute change */
75 /** FUSE specific file data */
77 /** Request reserved for flush and release */
78 struct fuse_req
*reserved_req
;
80 /** File handle used by userspace */
87 /** One input argument of a request */
93 /** The request input */
95 /** The request header */
96 struct fuse_in_header h
;
98 /** True if the data for the last argument is in req->pages */
101 /** Number of arguments */
104 /** Array of arguments */
105 struct fuse_in_arg args
[3];
108 /** One output argument of a request */
114 /** The request output */
116 /** Header returned from userspace */
117 struct fuse_out_header h
;
120 * The following bitfields are not changed during the request
124 /** Last argument is variable length (can be shorter than
128 /** Last argument is a list of pages to copy data to */
131 /** Zero partially or not copied pages */
132 unsigned page_zeroing
:1;
134 /** Number or arguments */
137 /** Array of arguments */
138 struct fuse_arg args
[3];
141 /** The request state */
142 enum fuse_req_state
{
154 * A request to the client
157 /** This can be on either pending processing or io lists in
159 struct list_head list
;
161 /** Entry on the interrupts list */
162 struct list_head intr_entry
;
167 /** Unique ID for the interrupt request */
171 * The following bitfields are either set once before the
172 * request is queued or setting/clearing them is protected by
176 /** True if the request has reply */
179 /** Force sending of the request even if interrupted */
182 /** The request was aborted */
185 /** Request is sent in the background */
186 unsigned background
:1;
188 /** The request has been interrupted */
189 unsigned interrupted
:1;
191 /** Data is being copied to/from the request */
194 /** Request is counted as "waiting" */
197 /** State of the request */
198 enum fuse_req_state state
;
200 /** The request input */
203 /** The request output */
206 /** Used to wake up the task waiting for completion of request*/
207 wait_queue_head_t waitq
;
209 /** Data for asynchronous requests */
211 struct fuse_forget_in forget_in
;
212 struct fuse_release_in release_in
;
213 struct fuse_init_in init_in
;
214 struct fuse_init_out init_out
;
215 struct fuse_read_in read_in
;
216 struct fuse_lk_in lk_in
;
220 struct page
*pages
[FUSE_MAX_PAGES_PER_REQ
];
222 /** number of pages in vector */
225 /** offset of data on first page */
226 unsigned page_offset
;
228 /** File used in the request (or NULL) */
229 struct fuse_file
*ff
;
231 /** vfsmount used in release */
232 struct vfsmount
*vfsmount
;
234 /** dentry used in release */
235 struct dentry
*dentry
;
237 /** Request completion callback */
238 void (*end
)(struct fuse_conn
*, struct fuse_req
*);
240 /** Request is stolen from fuse_file->reserved_req */
241 struct file
*stolen_file
;
247 * This structure is created, when the filesystem is mounted, and is
248 * destroyed, when the client device is closed and the filesystem is
252 /** Lock protecting accessess to members of this structure */
255 /** Mutex protecting against directory alias creation */
256 struct mutex inst_mutex
;
261 /** The user id for this mount */
264 /** The group id for this mount */
267 /** The fuse mount flags for this mount */
270 /** Maximum read size */
273 /** Maximum write size */
276 /** Readers of the connection are waiting on this */
277 wait_queue_head_t waitq
;
279 /** The list of pending requests */
280 struct list_head pending
;
282 /** The list of requests being processed */
283 struct list_head processing
;
285 /** The list of requests under I/O */
288 /** Number of requests currently in the background */
289 unsigned num_background
;
291 /** Pending interrupts */
292 struct list_head interrupts
;
294 /** Flag indicating if connection is blocked. This will be
295 the case before the INIT reply is received, and if there
296 are too many outstading backgrounds requests */
299 /** waitq for blocked connection */
300 wait_queue_head_t blocked_waitq
;
302 /** waitq for reserved requests */
303 wait_queue_head_t reserved_req_waitq
;
305 /** The next unique request id */
308 /** Connection established, cleared on umount, connection
309 abort and device release */
312 /** Connection failed (version mismatch). Cannot race with
313 setting other bitfields since it is only set once in INIT
314 reply, before any other request, and never cleared */
315 unsigned conn_error
: 1;
317 /** Connection successful. Only set in INIT */
318 unsigned conn_init
: 1;
320 /** Do readpages asynchronously? Only set in INIT */
321 unsigned async_read
: 1;
324 * The following bitfields are only for optimization purposes
325 * and hence races in setting them will not cause malfunction
328 /** Is fsync not implemented by fs? */
329 unsigned no_fsync
: 1;
331 /** Is fsyncdir not implemented by fs? */
332 unsigned no_fsyncdir
: 1;
334 /** Is flush not implemented by fs? */
335 unsigned no_flush
: 1;
337 /** Is setxattr not implemented by fs? */
338 unsigned no_setxattr
: 1;
340 /** Is getxattr not implemented by fs? */
341 unsigned no_getxattr
: 1;
343 /** Is listxattr not implemented by fs? */
344 unsigned no_listxattr
: 1;
346 /** Is removexattr not implemented by fs? */
347 unsigned no_removexattr
: 1;
349 /** Are file locking primitives not implemented by fs? */
350 unsigned no_lock
: 1;
352 /** Is access not implemented by fs? */
353 unsigned no_access
: 1;
355 /** Is create not implemented by fs? */
356 unsigned no_create
: 1;
358 /** Is interrupt not implemented by fs? */
359 unsigned no_interrupt
: 1;
361 /** Is bmap not implemented by fs? */
362 unsigned no_bmap
: 1;
364 /** The number of requests waiting for completion */
365 atomic_t num_waiting
;
367 /** Negotiated minor version */
370 /** Backing dev info */
371 struct backing_dev_info bdi
;
373 /** Entry on the fuse_conn_list */
374 struct list_head entry
;
379 /** Dentries in the control filesystem */
380 struct dentry
*ctl_dentry
[FUSE_CTL_NUM_DENTRIES
];
382 /** number of dentries used in the above array */
385 /** O_ASYNC requests */
386 struct fasync_struct
*fasync
;
388 /** Key for lock owner ID scrambling */
391 /** Reserved request for the DESTROY message */
392 struct fuse_req
*destroy_req
;
394 /** Version counter for attribute changes */
398 static inline struct fuse_conn
*get_fuse_conn_super(struct super_block
*sb
)
400 return sb
->s_fs_info
;
403 static inline struct fuse_conn
*get_fuse_conn(struct inode
*inode
)
405 return get_fuse_conn_super(inode
->i_sb
);
408 static inline struct fuse_inode
*get_fuse_inode(struct inode
*inode
)
410 return container_of(inode
, struct fuse_inode
, inode
);
413 static inline u64
get_node_id(struct inode
*inode
)
415 return get_fuse_inode(inode
)->nodeid
;
418 /** Device operations */
419 extern const struct file_operations fuse_dev_operations
;
422 * Get a filled in inode
424 struct inode
*fuse_iget(struct super_block
*sb
, unsigned long nodeid
,
425 int generation
, struct fuse_attr
*attr
,
426 u64 attr_valid
, u64 attr_version
);
429 * Send FORGET command
431 void fuse_send_forget(struct fuse_conn
*fc
, struct fuse_req
*req
,
432 unsigned long nodeid
, u64 nlookup
);
435 * Initialize READ or READDIR request
437 void fuse_read_fill(struct fuse_req
*req
, struct fuse_file
*ff
,
438 struct inode
*inode
, loff_t pos
, size_t count
, int opcode
);
441 * Send OPEN or OPENDIR request
443 int fuse_open_common(struct inode
*inode
, struct file
*file
, int isdir
);
445 struct fuse_file
*fuse_file_alloc(void);
446 void fuse_file_free(struct fuse_file
*ff
);
447 void fuse_finish_open(struct inode
*inode
, struct file
*file
,
448 struct fuse_file
*ff
, struct fuse_open_out
*outarg
);
450 /** Fill in ff->reserved_req with a RELEASE request */
451 void fuse_release_fill(struct fuse_file
*ff
, u64 nodeid
, int flags
, int opcode
);
454 * Send RELEASE or RELEASEDIR request
456 int fuse_release_common(struct inode
*inode
, struct file
*file
, int isdir
);
459 * Send FSYNC or FSYNCDIR request
461 int fuse_fsync_common(struct file
*file
, struct dentry
*de
, int datasync
,
465 * Initialize file operations on a regular file
467 void fuse_init_file_inode(struct inode
*inode
);
470 * Initialize inode operations on regular files and special files
472 void fuse_init_common(struct inode
*inode
);
475 * Initialize inode and file operations on a directory
477 void fuse_init_dir(struct inode
*inode
);
480 * Initialize inode operations on a symlink
482 void fuse_init_symlink(struct inode
*inode
);
485 * Change attributes of an inode
487 void fuse_change_attributes(struct inode
*inode
, struct fuse_attr
*attr
,
488 u64 attr_valid
, u64 attr_version
);
491 * Initialize the client device
493 int fuse_dev_init(void);
496 * Cleanup the client device
498 void fuse_dev_cleanup(void);
500 int fuse_ctl_init(void);
501 void fuse_ctl_cleanup(void);
506 struct fuse_req
*fuse_request_alloc(void);
511 void fuse_request_free(struct fuse_req
*req
);
514 * Get a request, may fail with -ENOMEM
516 struct fuse_req
*fuse_get_req(struct fuse_conn
*fc
);
519 * Gets a requests for a file operation, always succeeds
521 struct fuse_req
*fuse_get_req_nofail(struct fuse_conn
*fc
, struct file
*file
);
524 * Decrement reference count of a request. If count goes to zero free
527 void fuse_put_request(struct fuse_conn
*fc
, struct fuse_req
*req
);
530 * Send a request (synchronous)
532 void request_send(struct fuse_conn
*fc
, struct fuse_req
*req
);
535 * Send a request with no reply
537 void request_send_noreply(struct fuse_conn
*fc
, struct fuse_req
*req
);
540 * Send a request in the background
542 void request_send_background(struct fuse_conn
*fc
, struct fuse_req
*req
);
544 /* Abort all requests */
545 void fuse_abort_conn(struct fuse_conn
*fc
);
548 * Invalidate inode attributes
550 void fuse_invalidate_attr(struct inode
*inode
);
553 * Acquire reference to fuse_conn
555 struct fuse_conn
*fuse_conn_get(struct fuse_conn
*fc
);
558 * Release reference to fuse_conn
560 void fuse_conn_put(struct fuse_conn
*fc
);
563 * Add connection to control filesystem
565 int fuse_ctl_add_conn(struct fuse_conn
*fc
);
568 * Remove connection from control filesystem
570 void fuse_ctl_remove_conn(struct fuse_conn
*fc
);
573 * Is file type valid?
575 int fuse_valid_type(int m
);
578 * Is task allowed to perform filesystem operation?
580 int fuse_allow_task(struct fuse_conn
*fc
, struct task_struct
*task
);