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>
25 /** Max number of pages that can be used in a single read request */
26 #define FUSE_MAX_PAGES_PER_REQ 32
28 /** Maximum number of outstanding background requests */
29 #define FUSE_MAX_BACKGROUND 12
31 /** Congestion starts at 75% of maximum */
32 #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100)
34 /** Bias for fi->writectr, meaning new writepages must not be sent */
35 #define FUSE_NOWRITE INT_MIN
37 /** It could be as large as PATH_MAX, but would that have any uses? */
38 #define FUSE_NAME_MAX 1024
40 /** Number of dentries for each connection in the control filesystem */
41 #define FUSE_CTL_NUM_DENTRIES 3
43 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
44 module will check permissions based on the file mode. Otherwise no
45 permission checking is done in the kernel */
46 #define FUSE_DEFAULT_PERMISSIONS (1 << 0)
48 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user
49 doing the mount will be allowed to access the filesystem */
50 #define FUSE_ALLOW_OTHER (1 << 1)
52 /** List of active connections */
53 extern struct list_head fuse_conn_list;
55 /** Global mutex protecting fuse_conn_list and the control filesystem */
56 extern struct mutex fuse_mutex;
63 /** Unique ID, which identifies the inode between userspace
67 /** Number of lookups on this inode */
70 /** The request used for sending the FORGET message */
71 struct fuse_req *forget_req;
73 /** Time in jiffies until the file attributes are valid */
76 /** The sticky bit in inode->i_mode may have been removed, so
77 preserve the original mode */
80 /** Version of last attribute change */
83 /** Files usable in writepage. Protected by fc->lock */
84 struct list_head write_files;
86 /** Writepages pending on truncate or fsync */
87 struct list_head queued_writes;
89 /** Number of sent writes, a negative bias (FUSE_NOWRITE)
90 * means more writes are blocked */
93 /** Waitq for writepage completion */
94 wait_queue_head_t page_waitq;
96 /** List of writepage requestst (pending or sent) */
97 struct list_head writepages;
102 /** FUSE specific file data */
104 /** Fuse connection for this file */
105 struct fuse_conn *fc;
107 /** Request reserved for flush and release */
108 struct fuse_req *reserved_req;
110 /** Kernel file handle guaranteed to be unique */
113 /** File handle used by userspace */
116 /** Node id of this file */
122 /** FOPEN_* flags returned by open */
125 /** Entry on inode's write_files list */
126 struct list_head write_entry;
128 /** RB node to be linked on fuse_conn->polled_files */
129 struct rb_node polled_node;
131 /** Wait queue head for poll */
132 wait_queue_head_t poll_wait;
135 /** One input argument of a request */
141 /** The request input */
143 /** The request header */
144 struct fuse_in_header h;
146 /** True if the data for the last argument is in req->pages */
149 /** Number of arguments */
152 /** Array of arguments */
153 struct fuse_in_arg args[3];
156 /** One output argument of a request */
162 /** The request output */
164 /** Header returned from userspace */
165 struct fuse_out_header h;
168 * The following bitfields are not changed during the request
172 /** Last argument is variable length (can be shorter than
176 /** Last argument is a list of pages to copy data to */
179 /** Zero partially or not copied pages */
180 unsigned page_zeroing:1;
182 /** Number or arguments */
185 /** Array of arguments */
186 struct fuse_arg args[3];
189 /** The request state */
190 enum fuse_req_state {
200 * A request to the client
203 /** This can be on either pending processing or io lists in
205 struct list_head list;
207 /** Entry on the interrupts list */
208 struct list_head intr_entry;
213 /** Unique ID for the interrupt request */
217 * The following bitfields are either set once before the
218 * request is queued or setting/clearing them is protected by
222 /** True if the request has reply */
225 /** Force sending of the request even if interrupted */
228 /** The request was aborted */
231 /** Request is sent in the background */
232 unsigned background:1;
234 /** The request has been interrupted */
235 unsigned interrupted:1;
237 /** Data is being copied to/from the request */
240 /** Request is counted as "waiting" */
243 /** State of the request */
244 enum fuse_req_state state;
246 /** The request input */
249 /** The request output */
252 /** Used to wake up the task waiting for completion of request*/
253 wait_queue_head_t waitq;
255 /** Data for asynchronous requests */
257 struct fuse_forget_in forget_in;
259 struct fuse_release_in in;
262 struct fuse_init_in init_in;
263 struct fuse_init_out init_out;
264 struct cuse_init_in cuse_init_in;
265 struct cuse_init_out cuse_init_out;
267 struct fuse_read_in in;
271 struct fuse_write_in in;
272 struct fuse_write_out out;
274 struct fuse_lk_in lk_in;
278 struct page *pages[FUSE_MAX_PAGES_PER_REQ];
280 /** number of pages in vector */
283 /** offset of data on first page */
284 unsigned page_offset;
286 /** File used in the request (or NULL) */
287 struct fuse_file *ff;
289 /** Inode used in the request or NULL */
292 /** Link on fi->writepages */
293 struct list_head writepages_entry;
295 /** Request completion callback */
296 void (*end)(struct fuse_conn *, struct fuse_req *);
298 /** Request is stolen from fuse_file->reserved_req */
299 struct file *stolen_file;
305 * This structure is created, when the filesystem is mounted, and is
306 * destroyed, when the client device is closed and the filesystem is
310 /** Lock protecting accessess to members of this structure */
313 /** Mutex protecting against directory alias creation */
314 struct mutex inst_mutex;
319 /** The user id for this mount */
322 /** The group id for this mount */
325 /** The fuse mount flags for this mount */
328 /** Maximum read size */
331 /** Maximum write size */
334 /** Readers of the connection are waiting on this */
335 wait_queue_head_t waitq;
337 /** The list of pending requests */
338 struct list_head pending;
340 /** The list of requests being processed */
341 struct list_head processing;
343 /** The list of requests under I/O */
346 /** The next unique kernel file handle */
349 /** rbtree of fuse_files waiting for poll events indexed by ph */
350 struct rb_root polled_files;
352 /** Number of requests currently in the background */
353 unsigned num_background;
355 /** Number of background requests currently queued for userspace */
356 unsigned active_background;
358 /** The list of background requests set aside for later queuing */
359 struct list_head bg_queue;
361 /** Pending interrupts */
362 struct list_head interrupts;
364 /** Flag indicating if connection is blocked. This will be
365 the case before the INIT reply is received, and if there
366 are too many outstading backgrounds requests */
369 /** waitq for blocked connection */
370 wait_queue_head_t blocked_waitq;
372 /** waitq for reserved requests */
373 wait_queue_head_t reserved_req_waitq;
375 /** The next unique request id */
378 /** Connection established, cleared on umount, connection
379 abort and device release */
382 /** Connection failed (version mismatch). Cannot race with
383 setting other bitfields since it is only set once in INIT
384 reply, before any other request, and never cleared */
385 unsigned conn_error:1;
387 /** Connection successful. Only set in INIT */
388 unsigned conn_init:1;
390 /** Do readpages asynchronously? Only set in INIT */
391 unsigned async_read:1;
393 /** Do not send separate SETATTR request before open(O_TRUNC) */
394 unsigned atomic_o_trunc:1;
396 /** Filesystem supports NFS exporting. Only set in INIT */
397 unsigned export_support:1;
399 /** Set if bdi is valid */
400 unsigned bdi_initialized:1;
403 * The following bitfields are only for optimization purposes
404 * and hence races in setting them will not cause malfunction
407 /** Is fsync not implemented by fs? */
410 /** Is fsyncdir not implemented by fs? */
411 unsigned no_fsyncdir:1;
413 /** Is flush not implemented by fs? */
416 /** Is setxattr not implemented by fs? */
417 unsigned no_setxattr:1;
419 /** Is getxattr not implemented by fs? */
420 unsigned no_getxattr:1;
422 /** Is listxattr not implemented by fs? */
423 unsigned no_listxattr:1;
425 /** Is removexattr not implemented by fs? */
426 unsigned no_removexattr:1;
428 /** Are file locking primitives not implemented by fs? */
431 /** Is access not implemented by fs? */
432 unsigned no_access:1;
434 /** Is create not implemented by fs? */
435 unsigned no_create:1;
437 /** Is interrupt not implemented by fs? */
438 unsigned no_interrupt:1;
440 /** Is bmap not implemented by fs? */
443 /** Is poll not implemented by fs? */
446 /** Do multi-page cached writes */
447 unsigned big_writes:1;
449 /** The number of requests waiting for completion */
450 atomic_t num_waiting;
452 /** Negotiated minor version */
455 /** Backing dev info */
456 struct backing_dev_info bdi;
458 /** Entry on the fuse_conn_list */
459 struct list_head entry;
461 /** Device ID from super block */
464 /** Dentries in the control filesystem */
465 struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
467 /** number of dentries used in the above array */
470 /** O_ASYNC requests */
471 struct fasync_struct *fasync;
473 /** Key for lock owner ID scrambling */
476 /** Reserved request for the DESTROY message */
477 struct fuse_req *destroy_req;
479 /** Version counter for attribute changes */
482 /** Called on final put */
483 void (*release)(struct fuse_conn *);
486 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
488 return sb->s_fs_info;
491 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
493 return get_fuse_conn_super(inode->i_sb);
496 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
498 return container_of(inode, struct fuse_inode, inode);
501 static inline u64 get_node_id(struct inode *inode)
503 return get_fuse_inode(inode)->nodeid;
506 /** Device operations */
507 extern const struct file_operations fuse_dev_operations;
509 extern const struct dentry_operations fuse_dentry_operations;
512 * Get a filled in inode
514 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
515 int generation, struct fuse_attr *attr,
516 u64 attr_valid, u64 attr_version);
518 int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
519 struct fuse_entry_out *outarg, struct inode **inode);
522 * Send FORGET command
524 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
525 u64 nodeid, u64 nlookup);
528 * Initialize READ or READDIR request
530 void fuse_read_fill(struct fuse_req *req, struct file *file,
531 loff_t pos, size_t count, int opcode);
534 * Send OPEN or OPENDIR request
536 int fuse_open_common(struct inode *inode, struct file *file, bool isdir);
538 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc);
539 struct fuse_file *fuse_file_get(struct fuse_file *ff);
540 void fuse_file_free(struct fuse_file *ff);
541 void fuse_finish_open(struct inode *inode, struct file *file);
543 void fuse_sync_release(struct fuse_file *ff, int flags);
546 * Send RELEASE or RELEASEDIR request
548 void fuse_release_common(struct file *file, int opcode);
551 * Send FSYNC or FSYNCDIR request
553 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
559 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
560 struct fuse_notify_poll_wakeup_out *outarg);
563 * Initialize file operations on a regular file
565 void fuse_init_file_inode(struct inode *inode);
568 * Initialize inode operations on regular files and special files
570 void fuse_init_common(struct inode *inode);
573 * Initialize inode and file operations on a directory
575 void fuse_init_dir(struct inode *inode);
578 * Initialize inode operations on a symlink
580 void fuse_init_symlink(struct inode *inode);
583 * Change attributes of an inode
585 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
586 u64 attr_valid, u64 attr_version);
588 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
591 void fuse_truncate(struct address_space *mapping, loff_t offset);
594 * Initialize the client device
596 int fuse_dev_init(void);
599 * Cleanup the client device
601 void fuse_dev_cleanup(void);
603 int fuse_ctl_init(void);
604 void fuse_ctl_cleanup(void);
609 struct fuse_req *fuse_request_alloc(void);
611 struct fuse_req *fuse_request_alloc_nofs(void);
616 void fuse_request_free(struct fuse_req *req);
619 * Get a request, may fail with -ENOMEM
621 struct fuse_req *fuse_get_req(struct fuse_conn *fc);
624 * Gets a requests for a file operation, always succeeds
626 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
629 * Decrement reference count of a request. If count goes to zero free
632 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
635 * Send a request (synchronous)
637 void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req);
640 * Send a request with no reply
642 void fuse_request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
645 * Send a request in the background
647 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req);
649 void fuse_request_send_background_locked(struct fuse_conn *fc,
650 struct fuse_req *req);
652 /* Abort all requests */
653 void fuse_abort_conn(struct fuse_conn *fc);
656 * Invalidate inode attributes
658 void fuse_invalidate_attr(struct inode *inode);
660 void fuse_invalidate_entry_cache(struct dentry *entry);
663 * Acquire reference to fuse_conn
665 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
667 void fuse_conn_kill(struct fuse_conn *fc);
670 * Initialize fuse_conn
672 void fuse_conn_init(struct fuse_conn *fc);
675 * Release reference to fuse_conn
677 void fuse_conn_put(struct fuse_conn *fc);
680 * Add connection to control filesystem
682 int fuse_ctl_add_conn(struct fuse_conn *fc);
685 * Remove connection from control filesystem
687 void fuse_ctl_remove_conn(struct fuse_conn *fc);
690 * Is file type valid?
692 int fuse_valid_type(int m);
695 * Is task allowed to perform filesystem operation?
697 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
699 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
701 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
702 struct file *file, bool *refreshed);
704 void fuse_flush_writepages(struct inode *inode);
706 void fuse_set_nowrite(struct inode *inode);
707 void fuse_release_nowrite(struct inode *inode);
709 u64 fuse_get_attr_version(struct fuse_conn *fc);
711 int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
713 ssize_t fuse_direct_io(struct file *file, const char __user *buf,
714 size_t count, loff_t *ppos, int write);
715 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
717 unsigned fuse_file_poll(struct file *file, poll_table *wait);
718 int fuse_dev_release(struct inode *inode, struct file *file);
720 #endif /* _FS_FUSE_I_H */