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 /** Bias for fi->writectr, meaning new writepages must not be sent */
29 #define FUSE_NOWRITE INT_MIN
31 /** It could be as large as PATH_MAX, but would that have any uses? */
32 #define FUSE_NAME_MAX 1024
34 /** Number of dentries for each connection in the control filesystem */
35 #define FUSE_CTL_NUM_DENTRIES 3
37 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
38 module will check permissions based on the file mode. Otherwise no
39 permission checking is done in the kernel */
40 #define FUSE_DEFAULT_PERMISSIONS (1 << 0)
42 /** If the FUSE_ALLOW_OTHER flag is given, then not only the user
43 doing the mount will be allowed to access the filesystem */
44 #define FUSE_ALLOW_OTHER (1 << 1)
46 /** List of active connections */
47 extern struct list_head fuse_conn_list
;
49 /** Global mutex protecting fuse_conn_list and the control filesystem */
50 extern struct mutex fuse_mutex
;
57 /** Unique ID, which identifies the inode between userspace
61 /** Number of lookups on this inode */
64 /** The request used for sending the FORGET message */
65 struct fuse_req
*forget_req
;
67 /** Time in jiffies until the file attributes are valid */
70 /** The sticky bit in inode->i_mode may have been removed, so
71 preserve the original mode */
74 /** Version of last attribute change */
77 /** Files usable in writepage. Protected by fc->lock */
78 struct list_head write_files
;
80 /** Writepages pending on truncate or fsync */
81 struct list_head queued_writes
;
83 /** Number of sent writes, a negative bias (FUSE_NOWRITE)
84 * means more writes are blocked */
87 /** Waitq for writepage completion */
88 wait_queue_head_t page_waitq
;
90 /** List of writepage requestst (pending or sent) */
91 struct list_head writepages
;
96 /** FUSE specific file data */
98 /** Fuse connection for this file */
101 /** Request reserved for flush and release */
102 struct fuse_req
*reserved_req
;
104 /** Kernel file handle guaranteed to be unique */
107 /** File handle used by userspace */
110 /** Node id of this file */
116 /** FOPEN_* flags returned by open */
119 /** Entry on inode's write_files list */
120 struct list_head write_entry
;
122 /** RB node to be linked on fuse_conn->polled_files */
123 struct rb_node polled_node
;
125 /** Wait queue head for poll */
126 wait_queue_head_t poll_wait
;
129 /** One input argument of a request */
135 /** The request input */
137 /** The request header */
138 struct fuse_in_header h
;
140 /** True if the data for the last argument is in req->pages */
143 /** Number of arguments */
146 /** Array of arguments */
147 struct fuse_in_arg args
[3];
150 /** One output argument of a request */
156 /** The request output */
158 /** Header returned from userspace */
159 struct fuse_out_header h
;
162 * The following bitfields are not changed during the request
166 /** Last argument is variable length (can be shorter than
170 /** Last argument is a list of pages to copy data to */
173 /** Zero partially or not copied pages */
174 unsigned page_zeroing
:1;
176 /** Number or arguments */
179 /** Array of arguments */
180 struct fuse_arg args
[3];
183 /** The request state */
184 enum fuse_req_state
{
194 * A request to the client
197 /** This can be on either pending processing or io lists in
199 struct list_head list
;
201 /** Entry on the interrupts list */
202 struct list_head intr_entry
;
207 /** Unique ID for the interrupt request */
211 * The following bitfields are either set once before the
212 * request is queued or setting/clearing them is protected by
216 /** True if the request has reply */
219 /** Force sending of the request even if interrupted */
222 /** The request was aborted */
225 /** Request is sent in the background */
226 unsigned background
:1;
228 /** The request has been interrupted */
229 unsigned interrupted
:1;
231 /** Data is being copied to/from the request */
234 /** Request is counted as "waiting" */
237 /** State of the request */
238 enum fuse_req_state state
;
240 /** The request input */
243 /** The request output */
246 /** Used to wake up the task waiting for completion of request*/
247 wait_queue_head_t waitq
;
249 /** Data for asynchronous requests */
251 struct fuse_forget_in forget_in
;
253 struct fuse_release_in in
;
256 struct fuse_init_in init_in
;
257 struct fuse_init_out init_out
;
258 struct cuse_init_in cuse_init_in
;
259 struct cuse_init_out cuse_init_out
;
261 struct fuse_read_in in
;
265 struct fuse_write_in in
;
266 struct fuse_write_out out
;
268 struct fuse_lk_in lk_in
;
272 struct page
*pages
[FUSE_MAX_PAGES_PER_REQ
];
274 /** number of pages in vector */
277 /** offset of data on first page */
278 unsigned page_offset
;
280 /** File used in the request (or NULL) */
281 struct fuse_file
*ff
;
283 /** Inode used in the request or NULL */
286 /** Link on fi->writepages */
287 struct list_head writepages_entry
;
289 /** Request completion callback */
290 void (*end
)(struct fuse_conn
*, struct fuse_req
*);
292 /** Request is stolen from fuse_file->reserved_req */
293 struct file
*stolen_file
;
299 * This structure is created, when the filesystem is mounted, and is
300 * destroyed, when the client device is closed and the filesystem is
304 /** Lock protecting accessess to members of this structure */
307 /** Mutex protecting against directory alias creation */
308 struct mutex inst_mutex
;
313 /** The user id for this mount */
316 /** The group id for this mount */
319 /** The fuse mount flags for this mount */
322 /** Maximum read size */
325 /** Maximum write size */
328 /** Readers of the connection are waiting on this */
329 wait_queue_head_t waitq
;
331 /** The list of pending requests */
332 struct list_head pending
;
334 /** The list of requests being processed */
335 struct list_head processing
;
337 /** The list of requests under I/O */
340 /** The next unique kernel file handle */
343 /** rbtree of fuse_files waiting for poll events indexed by ph */
344 struct rb_root polled_files
;
346 /** Maximum number of outstanding background requests */
347 unsigned max_background
;
349 /** Number of background requests at which congestion starts */
350 unsigned congestion_threshold
;
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 /** Don't apply umask to creation modes */
450 unsigned dont_mask
:1;
452 /** The number of requests waiting for completion */
453 atomic_t num_waiting
;
455 /** Negotiated minor version */
458 /** Backing dev info */
459 struct backing_dev_info bdi
;
461 /** Entry on the fuse_conn_list */
462 struct list_head entry
;
464 /** Device ID from super block */
467 /** Dentries in the control filesystem */
468 struct dentry
*ctl_dentry
[FUSE_CTL_NUM_DENTRIES
];
470 /** number of dentries used in the above array */
473 /** O_ASYNC requests */
474 struct fasync_struct
*fasync
;
476 /** Key for lock owner ID scrambling */
479 /** Reserved request for the DESTROY message */
480 struct fuse_req
*destroy_req
;
482 /** Version counter for attribute changes */
485 /** Called on final put */
486 void (*release
)(struct fuse_conn
*);
488 /** Super block for this connection. */
489 struct super_block
*sb
;
491 /** Read/write semaphore to hold when accessing sb. */
492 struct rw_semaphore killsb
;
495 static inline struct fuse_conn
*get_fuse_conn_super(struct super_block
*sb
)
497 return sb
->s_fs_info
;
500 static inline struct fuse_conn
*get_fuse_conn(struct inode
*inode
)
502 return get_fuse_conn_super(inode
->i_sb
);
505 static inline struct fuse_inode
*get_fuse_inode(struct inode
*inode
)
507 return container_of(inode
, struct fuse_inode
, inode
);
510 static inline u64
get_node_id(struct inode
*inode
)
512 return get_fuse_inode(inode
)->nodeid
;
515 /** Device operations */
516 extern const struct file_operations fuse_dev_operations
;
518 extern const struct dentry_operations fuse_dentry_operations
;
521 * Inode to nodeid comparison.
523 int fuse_inode_eq(struct inode
*inode
, void *_nodeidp
);
526 * Get a filled in inode
528 struct inode
*fuse_iget(struct super_block
*sb
, u64 nodeid
,
529 int generation
, struct fuse_attr
*attr
,
530 u64 attr_valid
, u64 attr_version
);
532 int fuse_lookup_name(struct super_block
*sb
, u64 nodeid
, struct qstr
*name
,
533 struct fuse_entry_out
*outarg
, struct inode
**inode
);
536 * Send FORGET command
538 void fuse_send_forget(struct fuse_conn
*fc
, struct fuse_req
*req
,
539 u64 nodeid
, u64 nlookup
);
542 * Initialize READ or READDIR request
544 void fuse_read_fill(struct fuse_req
*req
, struct file
*file
,
545 loff_t pos
, size_t count
, int opcode
);
548 * Send OPEN or OPENDIR request
550 int fuse_open_common(struct inode
*inode
, struct file
*file
, bool isdir
);
552 struct fuse_file
*fuse_file_alloc(struct fuse_conn
*fc
);
553 struct fuse_file
*fuse_file_get(struct fuse_file
*ff
);
554 void fuse_file_free(struct fuse_file
*ff
);
555 void fuse_finish_open(struct inode
*inode
, struct file
*file
);
557 void fuse_sync_release(struct fuse_file
*ff
, int flags
);
560 * Send RELEASE or RELEASEDIR request
562 void fuse_release_common(struct file
*file
, int opcode
);
565 * Send FSYNC or FSYNCDIR request
567 int fuse_fsync_common(struct file
*file
, struct dentry
*de
, int datasync
,
573 int fuse_notify_poll_wakeup(struct fuse_conn
*fc
,
574 struct fuse_notify_poll_wakeup_out
*outarg
);
577 * Initialize file operations on a regular file
579 void fuse_init_file_inode(struct inode
*inode
);
582 * Initialize inode operations on regular files and special files
584 void fuse_init_common(struct inode
*inode
);
587 * Initialize inode and file operations on a directory
589 void fuse_init_dir(struct inode
*inode
);
592 * Initialize inode operations on a symlink
594 void fuse_init_symlink(struct inode
*inode
);
597 * Change attributes of an inode
599 void fuse_change_attributes(struct inode
*inode
, struct fuse_attr
*attr
,
600 u64 attr_valid
, u64 attr_version
);
602 void fuse_change_attributes_common(struct inode
*inode
, struct fuse_attr
*attr
,
605 void fuse_truncate(struct address_space
*mapping
, loff_t offset
);
608 * Initialize the client device
610 int fuse_dev_init(void);
613 * Cleanup the client device
615 void fuse_dev_cleanup(void);
617 int fuse_ctl_init(void);
618 void fuse_ctl_cleanup(void);
623 struct fuse_req
*fuse_request_alloc(void);
625 struct fuse_req
*fuse_request_alloc_nofs(void);
630 void fuse_request_free(struct fuse_req
*req
);
633 * Get a request, may fail with -ENOMEM
635 struct fuse_req
*fuse_get_req(struct fuse_conn
*fc
);
638 * Gets a requests for a file operation, always succeeds
640 struct fuse_req
*fuse_get_req_nofail(struct fuse_conn
*fc
, struct file
*file
);
643 * Decrement reference count of a request. If count goes to zero free
646 void fuse_put_request(struct fuse_conn
*fc
, struct fuse_req
*req
);
649 * Send a request (synchronous)
651 void fuse_request_send(struct fuse_conn
*fc
, struct fuse_req
*req
);
654 * Send a request with no reply
656 void fuse_request_send_noreply(struct fuse_conn
*fc
, struct fuse_req
*req
);
659 * Send a request in the background
661 void fuse_request_send_background(struct fuse_conn
*fc
, struct fuse_req
*req
);
663 void fuse_request_send_background_locked(struct fuse_conn
*fc
,
664 struct fuse_req
*req
);
666 /* Abort all requests */
667 void fuse_abort_conn(struct fuse_conn
*fc
);
670 * Invalidate inode attributes
672 void fuse_invalidate_attr(struct inode
*inode
);
674 void fuse_invalidate_entry_cache(struct dentry
*entry
);
677 * Acquire reference to fuse_conn
679 struct fuse_conn
*fuse_conn_get(struct fuse_conn
*fc
);
681 void fuse_conn_kill(struct fuse_conn
*fc
);
684 * Initialize fuse_conn
686 void fuse_conn_init(struct fuse_conn
*fc
);
689 * Release reference to fuse_conn
691 void fuse_conn_put(struct fuse_conn
*fc
);
694 * Add connection to control filesystem
696 int fuse_ctl_add_conn(struct fuse_conn
*fc
);
699 * Remove connection from control filesystem
701 void fuse_ctl_remove_conn(struct fuse_conn
*fc
);
704 * Is file type valid?
706 int fuse_valid_type(int m
);
709 * Is task allowed to perform filesystem operation?
711 int fuse_allow_task(struct fuse_conn
*fc
, struct task_struct
*task
);
713 u64
fuse_lock_owner_id(struct fuse_conn
*fc
, fl_owner_t id
);
715 int fuse_update_attributes(struct inode
*inode
, struct kstat
*stat
,
716 struct file
*file
, bool *refreshed
);
718 void fuse_flush_writepages(struct inode
*inode
);
720 void fuse_set_nowrite(struct inode
*inode
);
721 void fuse_release_nowrite(struct inode
*inode
);
723 u64
fuse_get_attr_version(struct fuse_conn
*fc
);
726 * File-system tells the kernel to invalidate cache for the given node id.
728 int fuse_reverse_inval_inode(struct super_block
*sb
, u64 nodeid
,
729 loff_t offset
, loff_t len
);
732 * File-system tells the kernel to invalidate parent attributes and
733 * the dentry matching parent/name.
735 int fuse_reverse_inval_entry(struct super_block
*sb
, u64 parent_nodeid
,
738 int fuse_do_open(struct fuse_conn
*fc
, u64 nodeid
, struct file
*file
,
740 ssize_t
fuse_direct_io(struct file
*file
, const char __user
*buf
,
741 size_t count
, loff_t
*ppos
, int write
);
742 long fuse_do_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
,
744 unsigned fuse_file_poll(struct file
*file
, poll_table
*wait
);
745 int fuse_dev_release(struct inode
*inode
, struct file
*file
);
747 #endif /* _FS_FUSE_I_H */