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>
18 #include <linux/rwsem.h>
20 /** Max number of pages that can be used in a single read request */
21 #define FUSE_MAX_PAGES_PER_REQ 32
23 /** Maximum number of outstanding background requests */
24 #define FUSE_MAX_BACKGROUND 12
26 /** Congestion starts at 75% of maximum */
27 #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100)
29 /** Bias for fi->writectr, meaning new writepages must not be sent */
30 #define FUSE_NOWRITE INT_MIN
32 /** It could be as large as PATH_MAX, but would that have any uses? */
33 #define FUSE_NAME_MAX 1024
35 /** Number of dentries for each connection in the control filesystem */
36 #define FUSE_CTL_NUM_DENTRIES 3
38 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
39 module will check permissions based on the file mode. Otherwise no
40 permission checking is done in the kernel */
41 #define FUSE_DEFAULT_PERMISSIONS (1 << 0)
43 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user
44 doing the mount will be allowed to access the filesystem */
45 #define FUSE_ALLOW_OTHER (1 << 1)
47 /** List of active connections */
48 extern struct list_head fuse_conn_list;
50 /** Global mutex protecting fuse_conn_list and the control filesystem */
51 extern struct mutex fuse_mutex;
58 /** Unique ID, which identifies the inode between userspace
62 /** Number of lookups on this inode */
65 /** The request used for sending the FORGET message */
66 struct fuse_req *forget_req;
68 /** Time in jiffies until the file attributes are valid */
71 /** The sticky bit in inode->i_mode may have been removed, so
72 preserve the original mode */
75 /** Version of last attribute change */
78 /** Files usable in writepage. Protected by fc->lock */
79 struct list_head write_files;
81 /** Writepages pending on truncate or fsync */
82 struct list_head queued_writes;
84 /** Number of sent writes, a negative bias (FUSE_NOWRITE)
85 * means more writes are blocked */
88 /** Waitq for writepage completion */
89 wait_queue_head_t page_waitq;
91 /** List of writepage requestst (pending or sent) */
92 struct list_head writepages;
95 /** FUSE specific file data */
97 /** Request reserved for flush and release */
98 struct fuse_req *reserved_req;
100 /** File handle used by userspace */
106 /** Entry on inode's write_files list */
107 struct list_head write_entry;
110 /** One input argument of a request */
116 /** The request input */
118 /** The request header */
119 struct fuse_in_header h;
121 /** True if the data for the last argument is in req->pages */
124 /** Number of arguments */
127 /** Array of arguments */
128 struct fuse_in_arg args[3];
131 /** One output argument of a request */
137 /** The request output */
139 /** Header returned from userspace */
140 struct fuse_out_header h;
143 * The following bitfields are not changed during the request
147 /** Last argument is variable length (can be shorter than
151 /** Last argument is a list of pages to copy data to */
154 /** Zero partially or not copied pages */
155 unsigned page_zeroing:1;
157 /** Number or arguments */
160 /** Array of arguments */
161 struct fuse_arg args[3];
164 /** The request state */
165 enum fuse_req_state {
177 * A request to the client
180 /** This can be on either pending processing or io lists in
182 struct list_head list;
184 /** Entry on the interrupts list */
185 struct list_head intr_entry;
190 /** Unique ID for the interrupt request */
194 * The following bitfields are either set once before the
195 * request is queued or setting/clearing them is protected by
199 /** True if the request has reply */
202 /** Force sending of the request even if interrupted */
205 /** The request was aborted */
208 /** Request is sent in the background */
209 unsigned background:1;
211 /** The request has been interrupted */
212 unsigned interrupted:1;
214 /** Data is being copied to/from the request */
217 /** Request is counted as "waiting" */
220 /** State of the request */
221 enum fuse_req_state state;
223 /** The request input */
226 /** The request output */
229 /** Used to wake up the task waiting for completion of request*/
230 wait_queue_head_t waitq;
232 /** Data for asynchronous requests */
234 struct fuse_forget_in forget_in;
236 struct fuse_release_in in;
237 struct vfsmount *vfsmount;
238 struct dentry *dentry;
240 struct fuse_init_in init_in;
241 struct fuse_init_out init_out;
242 struct fuse_read_in read_in;
244 struct fuse_write_in in;
245 struct fuse_write_out out;
247 struct fuse_lk_in lk_in;
251 struct page *pages[FUSE_MAX_PAGES_PER_REQ];
253 /** number of pages in vector */
256 /** offset of data on first page */
257 unsigned page_offset;
259 /** File used in the request (or NULL) */
260 struct fuse_file *ff;
262 /** Inode used in the request or NULL */
265 /** Link on fi->writepages */
266 struct list_head writepages_entry;
268 /** Request completion callback */
269 void (*end)(struct fuse_conn *, struct fuse_req *);
271 /** Request is stolen from fuse_file->reserved_req */
272 struct file *stolen_file;
278 * This structure is created, when the filesystem is mounted, and is
279 * destroyed, when the client device is closed and the filesystem is
283 /** Lock protecting accessess to members of this structure */
286 /** Mutex protecting against directory alias creation */
287 struct mutex inst_mutex;
292 /** The user id for this mount */
295 /** The group id for this mount */
298 /** The fuse mount flags for this mount */
301 /** Maximum read size */
304 /** Maximum write size */
307 /** Readers of the connection are waiting on this */
308 wait_queue_head_t waitq;
310 /** The list of pending requests */
311 struct list_head pending;
313 /** The list of requests being processed */
314 struct list_head processing;
316 /** The list of requests under I/O */
319 /** Number of requests currently in the background */
320 unsigned num_background;
322 /** Number of background requests currently queued for userspace */
323 unsigned active_background;
325 /** The list of background requests set aside for later queuing */
326 struct list_head bg_queue;
328 /** Pending interrupts */
329 struct list_head interrupts;
331 /** Flag indicating if connection is blocked. This will be
332 the case before the INIT reply is received, and if there
333 are too many outstading backgrounds requests */
336 /** waitq for blocked connection */
337 wait_queue_head_t blocked_waitq;
339 /** waitq for reserved requests */
340 wait_queue_head_t reserved_req_waitq;
342 /** The next unique request id */
345 /** Connection established, cleared on umount, connection
346 abort and device release */
349 /** Connection failed (version mismatch). Cannot race with
350 setting other bitfields since it is only set once in INIT
351 reply, before any other request, and never cleared */
352 unsigned conn_error : 1;
354 /** Connection successful. Only set in INIT */
355 unsigned conn_init : 1;
357 /** Do readpages asynchronously? Only set in INIT */
358 unsigned async_read : 1;
360 /** Do not send separate SETATTR request before open(O_TRUNC) */
361 unsigned atomic_o_trunc : 1;
364 * The following bitfields are only for optimization purposes
365 * and hence races in setting them will not cause malfunction
368 /** Is fsync not implemented by fs? */
369 unsigned no_fsync : 1;
371 /** Is fsyncdir not implemented by fs? */
372 unsigned no_fsyncdir : 1;
374 /** Is flush not implemented by fs? */
375 unsigned no_flush : 1;
377 /** Is setxattr not implemented by fs? */
378 unsigned no_setxattr : 1;
380 /** Is getxattr not implemented by fs? */
381 unsigned no_getxattr : 1;
383 /** Is listxattr not implemented by fs? */
384 unsigned no_listxattr : 1;
386 /** Is removexattr not implemented by fs? */
387 unsigned no_removexattr : 1;
389 /** Are file locking primitives not implemented by fs? */
390 unsigned no_lock : 1;
392 /** Is access not implemented by fs? */
393 unsigned no_access : 1;
395 /** Is create not implemented by fs? */
396 unsigned no_create : 1;
398 /** Is interrupt not implemented by fs? */
399 unsigned no_interrupt : 1;
401 /** Is bmap not implemented by fs? */
402 unsigned no_bmap : 1;
404 /** The number of requests waiting for completion */
405 atomic_t num_waiting;
407 /** Negotiated minor version */
410 /** Backing dev info */
411 struct backing_dev_info bdi;
413 /** Entry on the fuse_conn_list */
414 struct list_head entry;
416 /** Device ID from super block */
419 /** Dentries in the control filesystem */
420 struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
422 /** number of dentries used in the above array */
425 /** O_ASYNC requests */
426 struct fasync_struct *fasync;
428 /** Key for lock owner ID scrambling */
431 /** Reserved request for the DESTROY message */
432 struct fuse_req *destroy_req;
434 /** Version counter for attribute changes */
438 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
440 return sb->s_fs_info;
443 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
445 return get_fuse_conn_super(inode->i_sb);
448 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
450 return container_of(inode, struct fuse_inode, inode);
453 static inline u64 get_node_id(struct inode *inode)
455 return get_fuse_inode(inode)->nodeid;
458 /** Device operations */
459 extern const struct file_operations fuse_dev_operations;
462 * Get a filled in inode
464 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
465 int generation, struct fuse_attr *attr,
466 u64 attr_valid, u64 attr_version);
469 * Send FORGET command
471 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
472 unsigned long nodeid, u64 nlookup);
475 * Initialize READ or READDIR request
477 void fuse_read_fill(struct fuse_req *req, struct file *file,
478 struct inode *inode, loff_t pos, size_t count, int opcode);
481 * Send OPEN or OPENDIR request
483 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
485 struct fuse_file *fuse_file_alloc(void);
486 void fuse_file_free(struct fuse_file *ff);
487 void fuse_finish_open(struct inode *inode, struct file *file,
488 struct fuse_file *ff, struct fuse_open_out *outarg);
490 /** Fill in ff->reserved_req with a RELEASE request */
491 void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode);
494 * Send RELEASE or RELEASEDIR request
496 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
499 * Send FSYNC or FSYNCDIR request
501 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
505 * Initialize file operations on a regular file
507 void fuse_init_file_inode(struct inode *inode);
510 * Initialize inode operations on regular files and special files
512 void fuse_init_common(struct inode *inode);
515 * Initialize inode and file operations on a directory
517 void fuse_init_dir(struct inode *inode);
520 * Initialize inode operations on a symlink
522 void fuse_init_symlink(struct inode *inode);
525 * Change attributes of an inode
527 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
528 u64 attr_valid, u64 attr_version);
530 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
533 void fuse_truncate(struct address_space *mapping, loff_t offset);
536 * Initialize the client device
538 int fuse_dev_init(void);
541 * Cleanup the client device
543 void fuse_dev_cleanup(void);
545 int fuse_ctl_init(void);
546 void fuse_ctl_cleanup(void);
551 struct fuse_req *fuse_request_alloc(void);
553 struct fuse_req *fuse_request_alloc_nofs(void);
558 void fuse_request_free(struct fuse_req *req);
561 * Get a request, may fail with -ENOMEM
563 struct fuse_req *fuse_get_req(struct fuse_conn *fc);
566 * Gets a requests for a file operation, always succeeds
568 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
571 * Decrement reference count of a request. If count goes to zero free
574 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
577 * Send a request (synchronous)
579 void request_send(struct fuse_conn *fc, struct fuse_req *req);
582 * Send a request with no reply
584 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
587 * Send a request in the background
589 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
591 void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req);
593 /* Abort all requests */
594 void fuse_abort_conn(struct fuse_conn *fc);
597 * Invalidate inode attributes
599 void fuse_invalidate_attr(struct inode *inode);
602 * Acquire reference to fuse_conn
604 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
607 * Release reference to fuse_conn
609 void fuse_conn_put(struct fuse_conn *fc);
612 * Add connection to control filesystem
614 int fuse_ctl_add_conn(struct fuse_conn *fc);
617 * Remove connection from control filesystem
619 void fuse_ctl_remove_conn(struct fuse_conn *fc);
622 * Is file type valid?
624 int fuse_valid_type(int m);
627 * Is task allowed to perform filesystem operation?
629 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
631 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
633 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
634 struct file *file, bool *refreshed);
636 void fuse_flush_writepages(struct inode *inode);
638 void fuse_set_nowrite(struct inode *inode);
639 void fuse_release_nowrite(struct inode *inode);