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
;
62 /** Unique ID, which identifies the inode between userspace
66 /** Number of lookups on this inode */
69 /** The request used for sending the FORGET message */
70 struct fuse_req
*forget_req
;
72 /** Time in jiffies until the file attributes are valid */
75 /** The sticky bit in inode->i_mode may have been removed, so
76 preserve the original mode */
79 /** Version of last attribute change */
82 /** Files usable in writepage. Protected by fc->lock */
83 struct list_head write_files
;
85 /** Writepages pending on truncate or fsync */
86 struct list_head queued_writes
;
88 /** Number of sent writes, a negative bias (FUSE_NOWRITE)
89 * means more writes are blocked */
92 /** Waitq for writepage completion */
93 wait_queue_head_t page_waitq
;
95 /** List of writepage requestst (pending or sent) */
96 struct list_head writepages
;
101 /** FUSE specific file data */
103 /** Fuse connection for this file */
104 struct fuse_conn
*fc
;
106 /** Request reserved for flush and release */
107 struct fuse_req
*reserved_req
;
109 /** Kernel file handle guaranteed to be unique */
112 /** File handle used by userspace */
115 /** Node id of this file */
121 /** FOPEN_* flags returned by open */
124 /** Entry on inode's write_files list */
125 struct list_head write_entry
;
127 /** RB node to be linked on fuse_conn->polled_files */
128 struct rb_node polled_node
;
130 /** Wait queue head for poll */
131 wait_queue_head_t poll_wait
;
134 /** One input argument of a request */
140 /** The request input */
142 /** The request header */
143 struct fuse_in_header h
;
145 /** True if the data for the last argument is in req->pages */
148 /** Number of arguments */
151 /** Array of arguments */
152 struct fuse_in_arg args
[3];
155 /** One output argument of a request */
161 /** The request output */
163 /** Header returned from userspace */
164 struct fuse_out_header h
;
167 * The following bitfields are not changed during the request
171 /** Last argument is variable length (can be shorter than
175 /** Last argument is a list of pages to copy data to */
178 /** Zero partially or not copied pages */
179 unsigned page_zeroing
:1;
181 /** Pages may be replaced with new ones */
182 unsigned page_replace
:1;
184 /** Number or arguments */
187 /** Array of arguments */
188 struct fuse_arg args
[3];
191 /** The request state */
192 enum fuse_req_state
{
202 * A request to the client
205 /** This can be on either pending processing or io lists in
207 struct list_head list
;
209 /** Entry on the interrupts list */
210 struct list_head intr_entry
;
215 /** Unique ID for the interrupt request */
219 * The following bitfields are either set once before the
220 * request is queued or setting/clearing them is protected by
224 /** True if the request has reply */
227 /** Force sending of the request even if interrupted */
230 /** The request was aborted */
233 /** Request is sent in the background */
234 unsigned background
:1;
236 /** The request has been interrupted */
237 unsigned interrupted
:1;
239 /** Data is being copied to/from the request */
242 /** Request is counted as "waiting" */
245 /** State of the request */
246 enum fuse_req_state state
;
248 /** The request input */
251 /** The request output */
254 /** Used to wake up the task waiting for completion of request*/
255 wait_queue_head_t waitq
;
257 /** Data for asynchronous requests */
259 struct fuse_forget_in forget_in
;
262 struct fuse_release_in in
;
263 struct work_struct work
;
267 struct fuse_init_in init_in
;
268 struct fuse_init_out init_out
;
269 struct cuse_init_in cuse_init_in
;
270 struct cuse_init_out cuse_init_out
;
272 struct fuse_read_in in
;
276 struct fuse_write_in in
;
277 struct fuse_write_out out
;
279 struct fuse_lk_in lk_in
;
283 struct page
*pages
[FUSE_MAX_PAGES_PER_REQ
];
285 /** number of pages in vector */
288 /** offset of data on first page */
289 unsigned page_offset
;
291 /** File used in the request (or NULL) */
292 struct fuse_file
*ff
;
294 /** Inode used in the request or NULL */
297 /** Link on fi->writepages */
298 struct list_head writepages_entry
;
300 /** Request completion callback */
301 void (*end
)(struct fuse_conn
*, struct fuse_req
*);
303 /** Request is stolen from fuse_file->reserved_req */
304 struct file
*stolen_file
;
310 * This structure is created, when the filesystem is mounted, and is
311 * destroyed, when the client device is closed and the filesystem is
315 /** Lock protecting accessess to members of this structure */
318 /** Mutex protecting against directory alias creation */
319 struct mutex inst_mutex
;
324 /** The user id for this mount */
327 /** The group id for this mount */
330 /** The fuse mount flags for this mount */
333 /** Maximum read size */
336 /** Maximum write size */
339 /** Readers of the connection are waiting on this */
340 wait_queue_head_t waitq
;
342 /** The list of pending requests */
343 struct list_head pending
;
345 /** The list of requests being processed */
346 struct list_head processing
;
348 /** The list of requests under I/O */
351 /** The next unique kernel file handle */
354 /** rbtree of fuse_files waiting for poll events indexed by ph */
355 struct rb_root polled_files
;
357 /** Maximum number of outstanding background requests */
358 unsigned max_background
;
360 /** Number of background requests at which congestion starts */
361 unsigned congestion_threshold
;
363 /** Number of requests currently in the background */
364 unsigned num_background
;
366 /** Number of background requests currently queued for userspace */
367 unsigned active_background
;
369 /** The list of background requests set aside for later queuing */
370 struct list_head bg_queue
;
372 /** Pending interrupts */
373 struct list_head interrupts
;
375 /** Flag indicating if connection is blocked. This will be
376 the case before the INIT reply is received, and if there
377 are too many outstading backgrounds requests */
380 /** waitq for blocked connection */
381 wait_queue_head_t blocked_waitq
;
383 /** waitq for reserved requests */
384 wait_queue_head_t reserved_req_waitq
;
386 /** The next unique request id */
389 /** Connection established, cleared on umount, connection
390 abort and device release */
393 /** Connection failed (version mismatch). Cannot race with
394 setting other bitfields since it is only set once in INIT
395 reply, before any other request, and never cleared */
396 unsigned conn_error
:1;
398 /** Connection successful. Only set in INIT */
399 unsigned conn_init
:1;
401 /** Do readpages asynchronously? Only set in INIT */
402 unsigned async_read
:1;
404 /** Do not send separate SETATTR request before open(O_TRUNC) */
405 unsigned atomic_o_trunc
:1;
407 /** Filesystem supports NFS exporting. Only set in INIT */
408 unsigned export_support
:1;
410 /** Set if bdi is valid */
411 unsigned bdi_initialized
:1;
414 * The following bitfields are only for optimization purposes
415 * and hence races in setting them will not cause malfunction
418 /** Is fsync not implemented by fs? */
421 /** Is fsyncdir not implemented by fs? */
422 unsigned no_fsyncdir
:1;
424 /** Is flush not implemented by fs? */
427 /** Is setxattr not implemented by fs? */
428 unsigned no_setxattr
:1;
430 /** Is getxattr not implemented by fs? */
431 unsigned no_getxattr
:1;
433 /** Is listxattr not implemented by fs? */
434 unsigned no_listxattr
:1;
436 /** Is removexattr not implemented by fs? */
437 unsigned no_removexattr
:1;
439 /** Are file locking primitives not implemented by fs? */
442 /** Is access not implemented by fs? */
443 unsigned no_access
:1;
445 /** Is create not implemented by fs? */
446 unsigned no_create
:1;
448 /** Is interrupt not implemented by fs? */
449 unsigned no_interrupt
:1;
451 /** Is bmap not implemented by fs? */
454 /** Is poll not implemented by fs? */
457 /** Do multi-page cached writes */
458 unsigned big_writes
:1;
460 /** Don't apply umask to creation modes */
461 unsigned dont_mask
:1;
463 /** The number of requests waiting for completion */
464 atomic_t num_waiting
;
466 /** Negotiated minor version */
469 /** Backing dev info */
470 struct backing_dev_info bdi
;
472 /** Entry on the fuse_conn_list */
473 struct list_head entry
;
475 /** Device ID from super block */
478 /** Dentries in the control filesystem */
479 struct dentry
*ctl_dentry
[FUSE_CTL_NUM_DENTRIES
];
481 /** number of dentries used in the above array */
484 /** O_ASYNC requests */
485 struct fasync_struct
*fasync
;
487 /** Key for lock owner ID scrambling */
490 /** Reserved request for the DESTROY message */
491 struct fuse_req
*destroy_req
;
493 /** Version counter for attribute changes */
496 /** Called on final put */
497 void (*release
)(struct fuse_conn
*);
499 /** Super block for this connection. */
500 struct super_block
*sb
;
502 /** Read/write semaphore to hold when accessing sb. */
503 struct rw_semaphore killsb
;
506 static inline struct fuse_conn
*get_fuse_conn_super(struct super_block
*sb
)
508 return sb
->s_fs_info
;
511 static inline struct fuse_conn
*get_fuse_conn(struct inode
*inode
)
513 return get_fuse_conn_super(inode
->i_sb
);
516 static inline struct fuse_inode
*get_fuse_inode(struct inode
*inode
)
518 return container_of(inode
, struct fuse_inode
, inode
);
521 static inline u64
get_node_id(struct inode
*inode
)
523 return get_fuse_inode(inode
)->nodeid
;
526 /** Device operations */
527 extern const struct file_operations fuse_dev_operations
;
529 extern const struct dentry_operations fuse_dentry_operations
;
532 * Inode to nodeid comparison.
534 int fuse_inode_eq(struct inode
*inode
, void *_nodeidp
);
537 * Get a filled in inode
539 struct inode
*fuse_iget(struct super_block
*sb
, u64 nodeid
,
540 int generation
, struct fuse_attr
*attr
,
541 u64 attr_valid
, u64 attr_version
);
543 int fuse_lookup_name(struct super_block
*sb
, u64 nodeid
, struct qstr
*name
,
544 struct fuse_entry_out
*outarg
, struct inode
**inode
);
547 * Send FORGET command
549 void fuse_send_forget(struct fuse_conn
*fc
, struct fuse_req
*req
,
550 u64 nodeid
, u64 nlookup
);
553 * Initialize READ or READDIR request
555 void fuse_read_fill(struct fuse_req
*req
, struct file
*file
,
556 loff_t pos
, size_t count
, int opcode
);
559 * Send OPEN or OPENDIR request
561 int fuse_open_common(struct inode
*inode
, struct file
*file
, bool isdir
);
563 struct fuse_file
*fuse_file_alloc(struct fuse_conn
*fc
);
564 struct fuse_file
*fuse_file_get(struct fuse_file
*ff
);
565 void fuse_file_free(struct fuse_file
*ff
);
566 void fuse_finish_open(struct inode
*inode
, struct file
*file
);
568 void fuse_sync_release(struct fuse_file
*ff
, int flags
);
571 * Send RELEASE or RELEASEDIR request
573 void fuse_release_common(struct file
*file
, int opcode
);
576 * Send FSYNC or FSYNCDIR request
578 int fuse_fsync_common(struct file
*file
, int datasync
, int isdir
);
583 int fuse_notify_poll_wakeup(struct fuse_conn
*fc
,
584 struct fuse_notify_poll_wakeup_out
*outarg
);
587 * Initialize file operations on a regular file
589 void fuse_init_file_inode(struct inode
*inode
);
592 * Initialize inode operations on regular files and special files
594 void fuse_init_common(struct inode
*inode
);
597 * Initialize inode and file operations on a directory
599 void fuse_init_dir(struct inode
*inode
);
602 * Initialize inode operations on a symlink
604 void fuse_init_symlink(struct inode
*inode
);
607 * Change attributes of an inode
609 void fuse_change_attributes(struct inode
*inode
, struct fuse_attr
*attr
,
610 u64 attr_valid
, u64 attr_version
);
612 void fuse_change_attributes_common(struct inode
*inode
, struct fuse_attr
*attr
,
616 * Initialize the client device
618 int fuse_dev_init(void);
621 * Cleanup the client device
623 void fuse_dev_cleanup(void);
625 int fuse_ctl_init(void);
626 void fuse_ctl_cleanup(void);
631 struct fuse_req
*fuse_request_alloc(void);
633 struct fuse_req
*fuse_request_alloc_nofs(void);
638 void fuse_request_free(struct fuse_req
*req
);
641 * Get a request, may fail with -ENOMEM
643 struct fuse_req
*fuse_get_req(struct fuse_conn
*fc
);
646 * Gets a requests for a file operation, always succeeds
648 struct fuse_req
*fuse_get_req_nofail(struct fuse_conn
*fc
, struct file
*file
);
651 * Decrement reference count of a request. If count goes to zero free
654 void fuse_put_request(struct fuse_conn
*fc
, struct fuse_req
*req
);
657 * Send a request (synchronous)
659 void fuse_request_send(struct fuse_conn
*fc
, struct fuse_req
*req
);
662 * Send a request with no reply
664 void fuse_request_send_noreply(struct fuse_conn
*fc
, struct fuse_req
*req
);
667 * Send a request in the background
669 void fuse_request_send_background(struct fuse_conn
*fc
, struct fuse_req
*req
);
671 void fuse_request_send_background_locked(struct fuse_conn
*fc
,
672 struct fuse_req
*req
);
674 /* Abort all requests */
675 void fuse_abort_conn(struct fuse_conn
*fc
);
678 * Invalidate inode attributes
680 void fuse_invalidate_attr(struct inode
*inode
);
682 void fuse_invalidate_entry_cache(struct dentry
*entry
);
685 * Acquire reference to fuse_conn
687 struct fuse_conn
*fuse_conn_get(struct fuse_conn
*fc
);
689 void fuse_conn_kill(struct fuse_conn
*fc
);
692 * Initialize fuse_conn
694 void fuse_conn_init(struct fuse_conn
*fc
);
697 * Release reference to fuse_conn
699 void fuse_conn_put(struct fuse_conn
*fc
);
702 * Add connection to control filesystem
704 int fuse_ctl_add_conn(struct fuse_conn
*fc
);
707 * Remove connection from control filesystem
709 void fuse_ctl_remove_conn(struct fuse_conn
*fc
);
712 * Is file type valid?
714 int fuse_valid_type(int m
);
717 * Is task allowed to perform filesystem operation?
719 int fuse_allow_task(struct fuse_conn
*fc
, struct task_struct
*task
);
721 u64
fuse_lock_owner_id(struct fuse_conn
*fc
, fl_owner_t id
);
723 int fuse_update_attributes(struct inode
*inode
, struct kstat
*stat
,
724 struct file
*file
, bool *refreshed
);
726 void fuse_flush_writepages(struct inode
*inode
);
728 void fuse_set_nowrite(struct inode
*inode
);
729 void fuse_release_nowrite(struct inode
*inode
);
731 u64
fuse_get_attr_version(struct fuse_conn
*fc
);
734 * File-system tells the kernel to invalidate cache for the given node id.
736 int fuse_reverse_inval_inode(struct super_block
*sb
, u64 nodeid
,
737 loff_t offset
, loff_t len
);
740 * File-system tells the kernel to invalidate parent attributes and
741 * the dentry matching parent/name.
743 int fuse_reverse_inval_entry(struct super_block
*sb
, u64 parent_nodeid
,
746 int fuse_do_open(struct fuse_conn
*fc
, u64 nodeid
, struct file
*file
,
748 ssize_t
fuse_direct_io(struct file
*file
, const char __user
*buf
,
749 size_t count
, loff_t
*ppos
, int write
);
750 long fuse_do_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
,
752 unsigned fuse_file_poll(struct file
*file
, poll_table
*wait
);
753 int fuse_dev_release(struct inode
*inode
, struct file
*file
);
755 #endif /* _FS_FUSE_I_H */