2 FUSE: Filesystem in Userspace
3 Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
5 This program can be distributed under the terms of the GNU GPL.
12 #include <linux/fuse.h>
14 #include <linux/mount.h>
15 #include <linux/wait.h>
16 #include <linux/list.h>
17 #include <linux/spinlock.h>
19 #include <linux/backing-dev.h>
20 #include <linux/mutex.h>
21 #include <linux/rwsem.h>
22 #include <linux/rbtree.h>
23 #include <linux/poll.h>
24 #include <linux/workqueue.h>
26 /** Max number of pages that can be used in a single read request */
27 #define FUSE_MAX_PAGES_PER_REQ 32
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 5
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;
53 /** Module parameters */
54 extern unsigned max_user_bgreq;
55 extern unsigned max_user_congthresh;
57 /* One forget request */
58 struct fuse_forget_link {
59 struct fuse_forget_one forget_one;
60 struct fuse_forget_link *next;
68 /** Unique ID, which identifies the inode between userspace
72 /** Number of lookups on this inode */
75 /** The request used for sending the FORGET message */
76 struct fuse_forget_link *forget;
78 /** Time in jiffies until the file attributes are valid */
81 /** The sticky bit in inode->i_mode may have been removed, so
82 preserve the original mode */
85 /** 64 bit inode number */
88 /** Version of last attribute change */
91 /** Files usable in writepage. Protected by fc->lock */
92 struct list_head write_files;
94 /** Writepages pending on truncate or fsync */
95 struct list_head queued_writes;
97 /** Number of sent writes, a negative bias (FUSE_NOWRITE)
98 * means more writes are blocked */
101 /** Waitq for writepage completion */
102 wait_queue_head_t page_waitq;
104 /** List of writepage requestst (pending or sent) */
105 struct list_head writepages;
107 /** Miscellaneous bits describing inode state */
111 /** FUSE inode state bits */
113 /** An operation changing file size is in progress */
114 FUSE_I_SIZE_UNSTABLE,
119 /** FUSE specific file data */
121 /** Fuse connection for this file */
122 struct fuse_conn *fc;
124 /** Request reserved for flush and release */
125 struct fuse_req *reserved_req;
127 /** Kernel file handle guaranteed to be unique */
130 /** File handle used by userspace */
133 /** Node id of this file */
139 /** FOPEN_* flags returned by open */
142 /** Entry on inode's write_files list */
143 struct list_head write_entry;
145 /** RB node to be linked on fuse_conn->polled_files */
146 struct rb_node polled_node;
148 /** Wait queue head for poll */
149 wait_queue_head_t poll_wait;
151 /** Has flock been performed on this file? */
155 /** One input argument of a request */
161 /** The request input */
163 /** The request header */
164 struct fuse_in_header h;
166 /** True if the data for the last argument is in req->pages */
169 /** Number of arguments */
172 /** Array of arguments */
173 struct fuse_in_arg args[3];
176 /** One output argument of a request */
182 /** The request output */
184 /** Header returned from userspace */
185 struct fuse_out_header h;
188 * The following bitfields are not changed during the request
192 /** Last argument is variable length (can be shorter than
196 /** Last argument is a list of pages to copy data to */
199 /** Zero partially or not copied pages */
200 unsigned page_zeroing:1;
202 /** Pages may be replaced with new ones */
203 unsigned page_replace:1;
205 /** Number or arguments */
208 /** Array of arguments */
209 struct fuse_arg args[3];
212 /** The request state */
213 enum fuse_req_state {
223 * A request to the client
226 /** This can be on either pending processing or io lists in
228 struct list_head list;
230 /** Entry on the interrupts list */
231 struct list_head intr_entry;
236 /** Unique ID for the interrupt request */
240 * The following bitfields are either set once before the
241 * request is queued or setting/clearing them is protected by
245 /** True if the request has reply */
248 /** Force sending of the request even if interrupted */
251 /** The request was aborted */
254 /** Request is sent in the background */
255 unsigned background:1;
257 /** The request has been interrupted */
258 unsigned interrupted:1;
260 /** Data is being copied to/from the request */
263 /** Request is counted as "waiting" */
266 /** State of the request */
267 enum fuse_req_state state;
269 /** The request input */
272 /** The request output */
275 /** Used to wake up the task waiting for completion of request*/
276 wait_queue_head_t waitq;
278 /** Data for asynchronous requests */
282 struct fuse_release_in in;
283 struct work_struct work;
287 struct fuse_init_in init_in;
288 struct fuse_init_out init_out;
289 struct cuse_init_in cuse_init_in;
291 struct fuse_read_in in;
295 struct fuse_write_in in;
296 struct fuse_write_out out;
298 struct fuse_notify_retrieve_in retrieve_in;
299 struct fuse_lk_in lk_in;
303 struct page *pages[FUSE_MAX_PAGES_PER_REQ];
305 /** number of pages in vector */
308 /** offset of data on first page */
309 unsigned page_offset;
311 /** File used in the request (or NULL) */
312 struct fuse_file *ff;
314 /** Inode used in the request or NULL */
317 /** Link on fi->writepages */
318 struct list_head writepages_entry;
320 /** Request completion callback */
321 void (*end)(struct fuse_conn *, struct fuse_req *);
323 /** Request is stolen from fuse_file->reserved_req */
324 struct file *stolen_file;
330 * This structure is created, when the filesystem is mounted, and is
331 * destroyed, when the client device is closed and the filesystem is
335 /** Lock protecting accessess to members of this structure */
338 /** Mutex protecting against directory alias creation */
339 struct mutex inst_mutex;
344 /** The user id for this mount */
347 /** The group id for this mount */
350 /** The fuse mount flags for this mount */
353 /** Maximum read size */
356 /** Maximum write size */
359 /** Readers of the connection are waiting on this */
360 wait_queue_head_t waitq;
362 /** The list of pending requests */
363 struct list_head pending;
365 /** The list of requests being processed */
366 struct list_head processing;
368 /** The list of requests under I/O */
371 /** The next unique kernel file handle */
374 /** rbtree of fuse_files waiting for poll events indexed by ph */
375 struct rb_root polled_files;
377 /** Maximum number of outstanding background requests */
378 unsigned max_background;
380 /** Number of background requests at which congestion starts */
381 unsigned congestion_threshold;
383 /** Number of requests currently in the background */
384 unsigned num_background;
386 /** Number of background requests currently queued for userspace */
387 unsigned active_background;
389 /** The list of background requests set aside for later queuing */
390 struct list_head bg_queue;
392 /** Pending interrupts */
393 struct list_head interrupts;
395 /** Queue of pending forgets */
396 struct fuse_forget_link forget_list_head;
397 struct fuse_forget_link *forget_list_tail;
399 /** Batching of FORGET requests (positive indicates FORGET batch) */
402 /** Flag indicating if connection is blocked. This will be
403 the case before the INIT reply is received, and if there
404 are too many outstading backgrounds requests */
407 /** waitq for blocked connection */
408 wait_queue_head_t blocked_waitq;
410 /** waitq for reserved requests */
411 wait_queue_head_t reserved_req_waitq;
413 /** The next unique request id */
416 /** Connection established, cleared on umount, connection
417 abort and device release */
420 /** Connection failed (version mismatch). Cannot race with
421 setting other bitfields since it is only set once in INIT
422 reply, before any other request, and never cleared */
423 unsigned conn_error:1;
425 /** Connection successful. Only set in INIT */
426 unsigned conn_init:1;
428 /** Do readpages asynchronously? Only set in INIT */
429 unsigned async_read:1;
431 /** Do not send separate SETATTR request before open(O_TRUNC) */
432 unsigned atomic_o_trunc:1;
434 /** Filesystem supports NFS exporting. Only set in INIT */
435 unsigned export_support:1;
437 /** Set if bdi is valid */
438 unsigned bdi_initialized:1;
441 * The following bitfields are only for optimization purposes
442 * and hence races in setting them will not cause malfunction
445 /** Is fsync not implemented by fs? */
448 /** Is fsyncdir not implemented by fs? */
449 unsigned no_fsyncdir:1;
451 /** Is flush not implemented by fs? */
454 /** Is setxattr not implemented by fs? */
455 unsigned no_setxattr:1;
457 /** Is getxattr not implemented by fs? */
458 unsigned no_getxattr:1;
460 /** Is listxattr not implemented by fs? */
461 unsigned no_listxattr:1;
463 /** Is removexattr not implemented by fs? */
464 unsigned no_removexattr:1;
466 /** Are posix file locking primitives not implemented by fs? */
469 /** Is access not implemented by fs? */
470 unsigned no_access:1;
472 /** Is create not implemented by fs? */
473 unsigned no_create:1;
475 /** Is interrupt not implemented by fs? */
476 unsigned no_interrupt:1;
478 /** Is bmap not implemented by fs? */
481 /** Is poll not implemented by fs? */
484 /** Do multi-page cached writes */
485 unsigned big_writes:1;
487 /** Don't apply umask to creation modes */
488 unsigned dont_mask:1;
490 /** Are BSD file locking primitives not implemented by fs? */
493 /** The number of requests waiting for completion */
494 atomic_t num_waiting;
496 /** Negotiated minor version */
499 /** Backing dev info */
500 struct backing_dev_info bdi;
502 /** Entry on the fuse_conn_list */
503 struct list_head entry;
505 /** Device ID from super block */
508 /** Dentries in the control filesystem */
509 struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
511 /** number of dentries used in the above array */
514 /** O_ASYNC requests */
515 struct fasync_struct *fasync;
517 /** Key for lock owner ID scrambling */
520 /** Reserved request for the DESTROY message */
521 struct fuse_req *destroy_req;
523 /** Version counter for attribute changes */
526 /** Called on final put */
527 void (*release)(struct fuse_conn *);
529 /** Super block for this connection. */
530 struct super_block *sb;
532 /** Read/write semaphore to hold when accessing sb. */
533 struct rw_semaphore killsb;
536 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
538 return sb->s_fs_info;
541 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
543 return get_fuse_conn_super(inode->i_sb);
546 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
548 return container_of(inode, struct fuse_inode, inode);
551 static inline u64 get_node_id(struct inode *inode)
553 return get_fuse_inode(inode)->nodeid;
556 /** Device operations */
557 extern const struct file_operations fuse_dev_operations;
559 extern const struct dentry_operations fuse_dentry_operations;
562 * Inode to nodeid comparison.
564 int fuse_inode_eq(struct inode *inode, void *_nodeidp);
567 * Get a filled in inode
569 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
570 int generation, struct fuse_attr *attr,
571 u64 attr_valid, u64 attr_version);
573 int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
574 struct fuse_entry_out *outarg, struct inode **inode);
577 * Send FORGET command
579 void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
580 u64 nodeid, u64 nlookup);
582 struct fuse_forget_link *fuse_alloc_forget(void);
585 * Initialize READ or READDIR request
587 void fuse_read_fill(struct fuse_req *req, struct file *file,
588 loff_t pos, size_t count, int opcode);
591 * Send OPEN or OPENDIR request
593 int fuse_open_common(struct inode *inode, struct file *file, bool isdir);
595 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc);
596 struct fuse_file *fuse_file_get(struct fuse_file *ff);
597 void fuse_file_free(struct fuse_file *ff);
598 void fuse_finish_open(struct inode *inode, struct file *file);
600 void fuse_sync_release(struct fuse_file *ff, int flags);
603 * Send RELEASE or RELEASEDIR request
605 void fuse_release_common(struct file *file, int opcode);
608 * Send FSYNC or FSYNCDIR request
610 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
611 int datasync, int isdir);
616 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
617 struct fuse_notify_poll_wakeup_out *outarg);
620 * Initialize file operations on a regular file
622 void fuse_init_file_inode(struct inode *inode);
625 * Initialize inode operations on regular files and special files
627 void fuse_init_common(struct inode *inode);
630 * Initialize inode and file operations on a directory
632 void fuse_init_dir(struct inode *inode);
635 * Initialize inode operations on a symlink
637 void fuse_init_symlink(struct inode *inode);
640 * Change attributes of an inode
642 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
643 u64 attr_valid, u64 attr_version);
645 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
649 * Initialize the client device
651 int fuse_dev_init(void);
654 * Cleanup the client device
656 void fuse_dev_cleanup(void);
658 int fuse_ctl_init(void);
659 void fuse_ctl_cleanup(void);
664 struct fuse_req *fuse_request_alloc(void);
666 struct fuse_req *fuse_request_alloc_nofs(void);
671 void fuse_request_free(struct fuse_req *req);
674 * Get a request, may fail with -ENOMEM
676 struct fuse_req *fuse_get_req(struct fuse_conn *fc);
679 * Gets a requests for a file operation, always succeeds
681 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
684 * Decrement reference count of a request. If count goes to zero free
687 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
690 * Send a request (synchronous)
692 void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req);
695 * Send a request in the background
697 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req);
699 void fuse_request_send_background_locked(struct fuse_conn *fc,
700 struct fuse_req *req);
702 /* Abort all requests */
703 void fuse_abort_conn(struct fuse_conn *fc);
706 * Invalidate inode attributes
708 void fuse_invalidate_attr(struct inode *inode);
710 void fuse_invalidate_entry_cache(struct dentry *entry);
713 * Acquire reference to fuse_conn
715 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
717 void fuse_conn_kill(struct fuse_conn *fc);
720 * Initialize fuse_conn
722 void fuse_conn_init(struct fuse_conn *fc);
725 * Release reference to fuse_conn
727 void fuse_conn_put(struct fuse_conn *fc);
730 * Add connection to control filesystem
732 int fuse_ctl_add_conn(struct fuse_conn *fc);
735 * Remove connection from control filesystem
737 void fuse_ctl_remove_conn(struct fuse_conn *fc);
740 * Is file type valid?
742 int fuse_valid_type(int m);
745 * Is task allowed to perform filesystem operation?
747 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
749 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
751 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
752 struct file *file, bool *refreshed);
754 void fuse_flush_writepages(struct inode *inode);
756 void fuse_set_nowrite(struct inode *inode);
757 void fuse_release_nowrite(struct inode *inode);
759 u64 fuse_get_attr_version(struct fuse_conn *fc);
762 * File-system tells the kernel to invalidate cache for the given node id.
764 int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
765 loff_t offset, loff_t len);
768 * File-system tells the kernel to invalidate parent attributes and
769 * the dentry matching parent/name.
771 int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
774 int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
776 ssize_t fuse_direct_io(struct file *file, const char __user *buf,
777 size_t count, loff_t *ppos, int write);
778 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
780 unsigned fuse_file_poll(struct file *file, poll_table *wait);
781 int fuse_dev_release(struct inode *inode, struct file *file);
783 void fuse_write_update_size(struct inode *inode, loff_t pos);
785 #endif /* _FS_FUSE_I_H */