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;
100 /** FUSE specific file data */
102 /** Request reserved for flush and release */
103 struct fuse_req *reserved_req;
105 /** Kernel file handle guaranteed to be unique */
108 /** File handle used by userspace */
114 /** Entry on inode's write_files list */
115 struct list_head write_entry;
117 /** RB node to be linked on fuse_conn->polled_files */
118 struct rb_node polled_node;
120 /** Wait queue head for poll */
121 wait_queue_head_t poll_wait;
124 /** One input argument of a request */
130 /** The request input */
132 /** The request header */
133 struct fuse_in_header h;
135 /** True if the data for the last argument is in req->pages */
138 /** Number of arguments */
141 /** Array of arguments */
142 struct fuse_in_arg args[3];
145 /** One output argument of a request */
151 /** The request output */
153 /** Header returned from userspace */
154 struct fuse_out_header h;
157 * The following bitfields are not changed during the request
161 /** Last argument is variable length (can be shorter than
165 /** Last argument is a list of pages to copy data to */
168 /** Zero partially or not copied pages */
169 unsigned page_zeroing:1;
171 /** Number or arguments */
174 /** Array of arguments */
175 struct fuse_arg args[3];
178 /** The request state */
179 enum fuse_req_state {
191 * A request to the client
194 /** This can be on either pending processing or io lists in
196 struct list_head list;
198 /** Entry on the interrupts list */
199 struct list_head intr_entry;
204 /** Unique ID for the interrupt request */
208 * The following bitfields are either set once before the
209 * request is queued or setting/clearing them is protected by
213 /** True if the request has reply */
216 /** Force sending of the request even if interrupted */
219 /** The request was aborted */
222 /** Request is sent in the background */
223 unsigned background:1;
225 /** The request has been interrupted */
226 unsigned interrupted:1;
228 /** Data is being copied to/from the request */
231 /** Request is counted as "waiting" */
234 /** State of the request */
235 enum fuse_req_state state;
237 /** The request input */
240 /** The request output */
243 /** Used to wake up the task waiting for completion of request*/
244 wait_queue_head_t waitq;
246 /** Data for asynchronous requests */
248 struct fuse_forget_in forget_in;
250 struct fuse_release_in in;
251 struct vfsmount *vfsmount;
252 struct dentry *dentry;
254 struct fuse_init_in init_in;
255 struct fuse_init_out init_out;
257 struct fuse_read_in in;
261 struct fuse_write_in in;
262 struct fuse_write_out out;
264 struct fuse_lk_in lk_in;
268 struct page *pages[FUSE_MAX_PAGES_PER_REQ];
270 /** number of pages in vector */
273 /** offset of data on first page */
274 unsigned page_offset;
276 /** File used in the request (or NULL) */
277 struct fuse_file *ff;
279 /** Inode used in the request or NULL */
282 /** Link on fi->writepages */
283 struct list_head writepages_entry;
285 /** Request completion callback */
286 void (*end)(struct fuse_conn *, struct fuse_req *);
288 /** Request is stolen from fuse_file->reserved_req */
289 struct file *stolen_file;
295 * This structure is created, when the filesystem is mounted, and is
296 * destroyed, when the client device is closed and the filesystem is
300 /** Lock protecting accessess to members of this structure */
303 /** Mutex protecting against directory alias creation */
304 struct mutex inst_mutex;
309 /** The user id for this mount */
312 /** The group id for this mount */
315 /** The fuse mount flags for this mount */
318 /** Maximum read size */
321 /** Maximum write size */
324 /** Readers of the connection are waiting on this */
325 wait_queue_head_t waitq;
327 /** The list of pending requests */
328 struct list_head pending;
330 /** The list of requests being processed */
331 struct list_head processing;
333 /** The list of requests under I/O */
336 /** The next unique kernel file handle */
339 /** rbtree of fuse_files waiting for poll events indexed by ph */
340 struct rb_root polled_files;
342 /** Number of requests currently in the background */
343 unsigned num_background;
345 /** Number of background requests currently queued for userspace */
346 unsigned active_background;
348 /** The list of background requests set aside for later queuing */
349 struct list_head bg_queue;
351 /** Pending interrupts */
352 struct list_head interrupts;
354 /** Flag indicating if connection is blocked. This will be
355 the case before the INIT reply is received, and if there
356 are too many outstading backgrounds requests */
359 /** waitq for blocked connection */
360 wait_queue_head_t blocked_waitq;
362 /** waitq for reserved requests */
363 wait_queue_head_t reserved_req_waitq;
365 /** The next unique request id */
368 /** Connection established, cleared on umount, connection
369 abort and device release */
372 /** Connection failed (version mismatch). Cannot race with
373 setting other bitfields since it is only set once in INIT
374 reply, before any other request, and never cleared */
375 unsigned conn_error:1;
377 /** Connection successful. Only set in INIT */
378 unsigned conn_init:1;
380 /** Do readpages asynchronously? Only set in INIT */
381 unsigned async_read:1;
383 /** Do not send separate SETATTR request before open(O_TRUNC) */
384 unsigned atomic_o_trunc:1;
386 /** Filesystem supports NFS exporting. Only set in INIT */
387 unsigned export_support:1;
390 * The following bitfields are only for optimization purposes
391 * and hence races in setting them will not cause malfunction
394 /** Is fsync not implemented by fs? */
397 /** Is fsyncdir not implemented by fs? */
398 unsigned no_fsyncdir:1;
400 /** Is flush not implemented by fs? */
403 /** Is setxattr not implemented by fs? */
404 unsigned no_setxattr:1;
406 /** Is getxattr not implemented by fs? */
407 unsigned no_getxattr:1;
409 /** Is listxattr not implemented by fs? */
410 unsigned no_listxattr:1;
412 /** Is removexattr not implemented by fs? */
413 unsigned no_removexattr:1;
415 /** Are file locking primitives not implemented by fs? */
418 /** Is access not implemented by fs? */
419 unsigned no_access:1;
421 /** Is create not implemented by fs? */
422 unsigned no_create:1;
424 /** Is interrupt not implemented by fs? */
425 unsigned no_interrupt:1;
427 /** Is bmap not implemented by fs? */
430 /** Is poll not implemented by fs? */
433 /** Do multi-page cached writes */
434 unsigned big_writes:1;
436 /** The number of requests waiting for completion */
437 atomic_t num_waiting;
439 /** Negotiated minor version */
442 /** Backing dev info */
443 struct backing_dev_info bdi;
445 /** Entry on the fuse_conn_list */
446 struct list_head entry;
448 /** Device ID from super block */
451 /** Dentries in the control filesystem */
452 struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
454 /** number of dentries used in the above array */
457 /** O_ASYNC requests */
458 struct fasync_struct *fasync;
460 /** Key for lock owner ID scrambling */
463 /** Reserved request for the DESTROY message */
464 struct fuse_req *destroy_req;
466 /** Version counter for attribute changes */
469 /** Called on final put */
470 void (*release)(struct fuse_conn *);
473 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
475 return sb->s_fs_info;
478 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
480 return get_fuse_conn_super(inode->i_sb);
483 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
485 return container_of(inode, struct fuse_inode, inode);
488 static inline u64 get_node_id(struct inode *inode)
490 return get_fuse_inode(inode)->nodeid;
493 /** Device operations */
494 extern const struct file_operations fuse_dev_operations;
496 extern const struct dentry_operations fuse_dentry_operations;
499 * Get a filled in inode
501 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
502 int generation, struct fuse_attr *attr,
503 u64 attr_valid, u64 attr_version);
505 int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
506 struct fuse_entry_out *outarg, struct inode **inode);
509 * Send FORGET command
511 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
512 u64 nodeid, u64 nlookup);
515 * Initialize READ or READDIR request
517 void fuse_read_fill(struct fuse_req *req, struct file *file,
518 struct inode *inode, loff_t pos, size_t count, int opcode);
521 * Send OPEN or OPENDIR request
523 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
525 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc);
526 void fuse_file_free(struct fuse_file *ff);
527 void fuse_finish_open(struct inode *inode, struct file *file,
528 struct fuse_file *ff, struct fuse_open_out *outarg);
530 /** Fill in ff->reserved_req with a RELEASE request */
531 void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode);
534 * Send RELEASE or RELEASEDIR request
536 int fuse_release_common(struct inode *inode, struct file *file, int isdir);
539 * Send FSYNC or FSYNCDIR request
541 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
547 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
548 struct fuse_notify_poll_wakeup_out *outarg);
551 * Initialize file operations on a regular file
553 void fuse_init_file_inode(struct inode *inode);
556 * Initialize inode operations on regular files and special files
558 void fuse_init_common(struct inode *inode);
561 * Initialize inode and file operations on a directory
563 void fuse_init_dir(struct inode *inode);
566 * Initialize inode operations on a symlink
568 void fuse_init_symlink(struct inode *inode);
571 * Change attributes of an inode
573 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
574 u64 attr_valid, u64 attr_version);
576 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
579 void fuse_truncate(struct address_space *mapping, loff_t offset);
582 * Initialize the client device
584 int fuse_dev_init(void);
587 * Cleanup the client device
589 void fuse_dev_cleanup(void);
591 int fuse_ctl_init(void);
592 void fuse_ctl_cleanup(void);
597 struct fuse_req *fuse_request_alloc(void);
599 struct fuse_req *fuse_request_alloc_nofs(void);
604 void fuse_request_free(struct fuse_req *req);
607 * Get a request, may fail with -ENOMEM
609 struct fuse_req *fuse_get_req(struct fuse_conn *fc);
612 * Gets a requests for a file operation, always succeeds
614 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
617 * Decrement reference count of a request. If count goes to zero free
620 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
623 * Send a request (synchronous)
625 void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req);
628 * Send a request with no reply
630 void fuse_request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
633 * Send a request in the background
635 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req);
637 void fuse_request_send_background_locked(struct fuse_conn *fc,
638 struct fuse_req *req);
640 /* Abort all requests */
641 void fuse_abort_conn(struct fuse_conn *fc);
644 * Invalidate inode attributes
646 void fuse_invalidate_attr(struct inode *inode);
648 void fuse_invalidate_entry_cache(struct dentry *entry);
651 * Acquire reference to fuse_conn
653 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
656 * Initialize fuse_conn
658 int fuse_conn_init(struct fuse_conn *fc, struct super_block *sb);
661 * Release reference to fuse_conn
663 void fuse_conn_put(struct fuse_conn *fc);
666 * Add connection to control filesystem
668 int fuse_ctl_add_conn(struct fuse_conn *fc);
671 * Remove connection from control filesystem
673 void fuse_ctl_remove_conn(struct fuse_conn *fc);
676 * Is file type valid?
678 int fuse_valid_type(int m);
681 * Is task allowed to perform filesystem operation?
683 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
685 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
687 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
688 struct file *file, bool *refreshed);
690 void fuse_flush_writepages(struct inode *inode);
692 void fuse_set_nowrite(struct inode *inode);
693 void fuse_release_nowrite(struct inode *inode);
695 u64 fuse_get_attr_version(struct fuse_conn *fc);
697 #endif /* _FS_FUSE_I_H */