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 /** Number of page pointers embedded in fuse_req */
48 #define FUSE_REQ_INLINE_PAGES 1
50 /** List of active connections */
51 extern struct list_head fuse_conn_list;
53 /** Global mutex protecting fuse_conn_list and the control filesystem */
54 extern struct mutex fuse_mutex;
56 /** Module parameters */
57 extern unsigned max_user_bgreq;
58 extern unsigned max_user_congthresh;
60 /* One forget request */
61 struct fuse_forget_link {
62 struct fuse_forget_one forget_one;
63 struct fuse_forget_link *next;
71 /** Unique ID, which identifies the inode between userspace
75 /** Number of lookups on this inode */
78 /** The request used for sending the FORGET message */
79 struct fuse_forget_link *forget;
81 /** Time in jiffies until the file attributes are valid */
84 /** The sticky bit in inode->i_mode may have been removed, so
85 preserve the original mode */
88 /** 64 bit inode number */
91 /** Version of last attribute change */
94 /** Files usable in writepage. Protected by fc->lock */
95 struct list_head write_files;
97 /** Writepages pending on truncate or fsync */
98 struct list_head queued_writes;
100 /** Number of sent writes, a negative bias (FUSE_NOWRITE)
101 * means more writes are blocked */
104 /** Waitq for writepage completion */
105 wait_queue_head_t page_waitq;
107 /** List of writepage requestst (pending or sent) */
108 struct list_head writepages;
113 /** FUSE specific file data */
115 /** Fuse connection for this file */
116 struct fuse_conn *fc;
118 /** Request reserved for flush and release */
119 struct fuse_req *reserved_req;
121 /** Kernel file handle guaranteed to be unique */
124 /** File handle used by userspace */
127 /** Node id of this file */
133 /** FOPEN_* flags returned by open */
136 /** Entry on inode's write_files list */
137 struct list_head write_entry;
139 /** RB node to be linked on fuse_conn->polled_files */
140 struct rb_node polled_node;
142 /** Wait queue head for poll */
143 wait_queue_head_t poll_wait;
145 /** Has flock been performed on this file? */
149 /** One input argument of a request */
155 /** The request input */
157 /** The request header */
158 struct fuse_in_header h;
160 /** True if the data for the last argument is in req->pages */
163 /** Number of arguments */
166 /** Array of arguments */
167 struct fuse_in_arg args[3];
170 /** One output argument of a request */
176 /** The request output */
178 /** Header returned from userspace */
179 struct fuse_out_header h;
182 * The following bitfields are not changed during the request
186 /** Last argument is variable length (can be shorter than
190 /** Last argument is a list of pages to copy data to */
193 /** Zero partially or not copied pages */
194 unsigned page_zeroing:1;
196 /** Pages may be replaced with new ones */
197 unsigned page_replace:1;
199 /** Number or arguments */
202 /** Array of arguments */
203 struct fuse_arg args[3];
206 /** FUSE page descriptor */
207 struct fuse_page_desc {
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;
305 /** page-descriptor vector */
306 struct fuse_page_desc *page_descs;
308 /** size of the 'pages' array */
311 /** inline page vector */
312 struct page *inline_pages[FUSE_REQ_INLINE_PAGES];
314 /** inline page-descriptor vector */
315 struct fuse_page_desc inline_page_descs[FUSE_REQ_INLINE_PAGES];
317 /** number of pages in vector */
320 /** File used in the request (or NULL) */
321 struct fuse_file *ff;
323 /** Inode used in the request or NULL */
326 /** Link on fi->writepages */
327 struct list_head writepages_entry;
329 /** Request completion callback */
330 void (*end)(struct fuse_conn *, struct fuse_req *);
332 /** Request is stolen from fuse_file->reserved_req */
333 struct file *stolen_file;
339 * This structure is created, when the filesystem is mounted, and is
340 * destroyed, when the client device is closed and the filesystem is
344 /** Lock protecting accessess to members of this structure */
347 /** Mutex protecting against directory alias creation */
348 struct mutex inst_mutex;
353 /** The user id for this mount */
356 /** The group id for this mount */
359 /** The fuse mount flags for this mount */
362 /** Maximum read size */
365 /** Maximum write size */
368 /** Readers of the connection are waiting on this */
369 wait_queue_head_t waitq;
371 /** The list of pending requests */
372 struct list_head pending;
374 /** The list of requests being processed */
375 struct list_head processing;
377 /** The list of requests under I/O */
380 /** The next unique kernel file handle */
383 /** rbtree of fuse_files waiting for poll events indexed by ph */
384 struct rb_root polled_files;
386 /** Maximum number of outstanding background requests */
387 unsigned max_background;
389 /** Number of background requests at which congestion starts */
390 unsigned congestion_threshold;
392 /** Number of requests currently in the background */
393 unsigned num_background;
395 /** Number of background requests currently queued for userspace */
396 unsigned active_background;
398 /** The list of background requests set aside for later queuing */
399 struct list_head bg_queue;
401 /** Pending interrupts */
402 struct list_head interrupts;
404 /** Queue of pending forgets */
405 struct fuse_forget_link forget_list_head;
406 struct fuse_forget_link *forget_list_tail;
408 /** Batching of FORGET requests (positive indicates FORGET batch) */
411 /** Flag indicating if connection is blocked. This will be
412 the case before the INIT reply is received, and if there
413 are too many outstading backgrounds requests */
416 /** waitq for blocked connection */
417 wait_queue_head_t blocked_waitq;
419 /** waitq for reserved requests */
420 wait_queue_head_t reserved_req_waitq;
422 /** The next unique request id */
425 /** Connection established, cleared on umount, connection
426 abort and device release */
429 /** Connection failed (version mismatch). Cannot race with
430 setting other bitfields since it is only set once in INIT
431 reply, before any other request, and never cleared */
432 unsigned conn_error:1;
434 /** Connection successful. Only set in INIT */
435 unsigned conn_init:1;
437 /** Do readpages asynchronously? Only set in INIT */
438 unsigned async_read:1;
440 /** Do not send separate SETATTR request before open(O_TRUNC) */
441 unsigned atomic_o_trunc:1;
443 /** Filesystem supports NFS exporting. Only set in INIT */
444 unsigned export_support:1;
446 /** Set if bdi is valid */
447 unsigned bdi_initialized:1;
450 * The following bitfields are only for optimization purposes
451 * and hence races in setting them will not cause malfunction
454 /** Is fsync not implemented by fs? */
457 /** Is fsyncdir not implemented by fs? */
458 unsigned no_fsyncdir:1;
460 /** Is flush not implemented by fs? */
463 /** Is setxattr not implemented by fs? */
464 unsigned no_setxattr:1;
466 /** Is getxattr not implemented by fs? */
467 unsigned no_getxattr:1;
469 /** Is listxattr not implemented by fs? */
470 unsigned no_listxattr:1;
472 /** Is removexattr not implemented by fs? */
473 unsigned no_removexattr:1;
475 /** Are posix file locking primitives not implemented by fs? */
478 /** Is access not implemented by fs? */
479 unsigned no_access:1;
481 /** Is create not implemented by fs? */
482 unsigned no_create:1;
484 /** Is interrupt not implemented by fs? */
485 unsigned no_interrupt:1;
487 /** Is bmap not implemented by fs? */
490 /** Is poll not implemented by fs? */
493 /** Do multi-page cached writes */
494 unsigned big_writes:1;
496 /** Don't apply umask to creation modes */
497 unsigned dont_mask:1;
499 /** Are BSD file locking primitives not implemented by fs? */
502 /** Is fallocate not implemented by fs? */
503 unsigned no_fallocate:1;
505 /** Use enhanced/automatic page cache invalidation. */
506 unsigned auto_inval_data:1;
508 /** Does the filesystem support readdir-plus? */
509 unsigned do_readdirplus:1;
511 /** The number of requests waiting for completion */
512 atomic_t num_waiting;
514 /** Negotiated minor version */
517 /** Backing dev info */
518 struct backing_dev_info bdi;
520 /** Entry on the fuse_conn_list */
521 struct list_head entry;
523 /** Device ID from super block */
526 /** Dentries in the control filesystem */
527 struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
529 /** number of dentries used in the above array */
532 /** O_ASYNC requests */
533 struct fasync_struct *fasync;
535 /** Key for lock owner ID scrambling */
538 /** Reserved request for the DESTROY message */
539 struct fuse_req *destroy_req;
541 /** Version counter for attribute changes */
544 /** Called on final put */
545 void (*release)(struct fuse_conn *);
547 /** Super block for this connection. */
548 struct super_block *sb;
550 /** Read/write semaphore to hold when accessing sb. */
551 struct rw_semaphore killsb;
554 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
556 return sb->s_fs_info;
559 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
561 return get_fuse_conn_super(inode->i_sb);
564 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
566 return container_of(inode, struct fuse_inode, inode);
569 static inline u64 get_node_id(struct inode *inode)
571 return get_fuse_inode(inode)->nodeid;
574 /** Device operations */
575 extern const struct file_operations fuse_dev_operations;
577 extern const struct dentry_operations fuse_dentry_operations;
580 * Inode to nodeid comparison.
582 int fuse_inode_eq(struct inode *inode, void *_nodeidp);
585 * Get a filled in inode
587 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
588 int generation, struct fuse_attr *attr,
589 u64 attr_valid, u64 attr_version);
591 int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
592 struct fuse_entry_out *outarg, struct inode **inode);
595 * Send FORGET command
597 void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
598 u64 nodeid, u64 nlookup);
600 struct fuse_forget_link *fuse_alloc_forget(void);
602 /* Used by READDIRPLUS */
603 void fuse_force_forget(struct file *file, u64 nodeid);
606 * Initialize READ or READDIR request
608 void fuse_read_fill(struct fuse_req *req, struct file *file,
609 loff_t pos, size_t count, int opcode);
612 * Send OPEN or OPENDIR request
614 int fuse_open_common(struct inode *inode, struct file *file, bool isdir);
616 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc);
617 struct fuse_file *fuse_file_get(struct fuse_file *ff);
618 void fuse_file_free(struct fuse_file *ff);
619 void fuse_finish_open(struct inode *inode, struct file *file);
621 void fuse_sync_release(struct fuse_file *ff, int flags);
624 * Send RELEASE or RELEASEDIR request
626 void fuse_release_common(struct file *file, int opcode);
629 * Send FSYNC or FSYNCDIR request
631 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
632 int datasync, int isdir);
637 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
638 struct fuse_notify_poll_wakeup_out *outarg);
641 * Initialize file operations on a regular file
643 void fuse_init_file_inode(struct inode *inode);
646 * Initialize inode operations on regular files and special files
648 void fuse_init_common(struct inode *inode);
651 * Initialize inode and file operations on a directory
653 void fuse_init_dir(struct inode *inode);
656 * Initialize inode operations on a symlink
658 void fuse_init_symlink(struct inode *inode);
661 * Change attributes of an inode
663 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
664 u64 attr_valid, u64 attr_version);
666 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
670 * Initialize the client device
672 int fuse_dev_init(void);
675 * Cleanup the client device
677 void fuse_dev_cleanup(void);
679 int fuse_ctl_init(void);
680 void fuse_ctl_cleanup(void);
685 struct fuse_req *fuse_request_alloc(unsigned npages);
687 struct fuse_req *fuse_request_alloc_nofs(unsigned npages);
692 void fuse_request_free(struct fuse_req *req);
695 * Get a request, may fail with -ENOMEM,
696 * caller should specify # elements in req->pages[] explicitly
698 struct fuse_req *fuse_get_req(struct fuse_conn *fc, unsigned npages);
701 * Get a request, may fail with -ENOMEM,
702 * useful for callers who doesn't use req->pages[]
704 static inline struct fuse_req *fuse_get_req_nopages(struct fuse_conn *fc)
706 return fuse_get_req(fc, 0);
710 * Gets a requests for a file operation, always succeeds
712 struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
716 * Decrement reference count of a request. If count goes to zero free
719 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
722 * Send a request (synchronous)
724 void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req);
727 * Send a request in the background
729 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req);
731 void fuse_request_send_background_locked(struct fuse_conn *fc,
732 struct fuse_req *req);
734 /* Abort all requests */
735 void fuse_abort_conn(struct fuse_conn *fc);
738 * Invalidate inode attributes
740 void fuse_invalidate_attr(struct inode *inode);
742 void fuse_invalidate_entry_cache(struct dentry *entry);
745 * Acquire reference to fuse_conn
747 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
749 void fuse_conn_kill(struct fuse_conn *fc);
752 * Initialize fuse_conn
754 void fuse_conn_init(struct fuse_conn *fc);
757 * Release reference to fuse_conn
759 void fuse_conn_put(struct fuse_conn *fc);
762 * Add connection to control filesystem
764 int fuse_ctl_add_conn(struct fuse_conn *fc);
767 * Remove connection from control filesystem
769 void fuse_ctl_remove_conn(struct fuse_conn *fc);
772 * Is file type valid?
774 int fuse_valid_type(int m);
777 * Is task allowed to perform filesystem operation?
779 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
781 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
783 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
784 struct file *file, bool *refreshed);
786 void fuse_flush_writepages(struct inode *inode);
788 void fuse_set_nowrite(struct inode *inode);
789 void fuse_release_nowrite(struct inode *inode);
791 u64 fuse_get_attr_version(struct fuse_conn *fc);
794 * File-system tells the kernel to invalidate cache for the given node id.
796 int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
797 loff_t offset, loff_t len);
800 * File-system tells the kernel to invalidate parent attributes and
801 * the dentry matching parent/name.
803 * If the child_nodeid is non-zero and:
804 * - matches the inode number for the dentry matching parent/name,
805 * - is not a mount point
806 * - is a file or oan empty directory
807 * then the dentry is unhashed (d_delete()).
809 int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
810 u64 child_nodeid, struct qstr *name);
812 int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
814 ssize_t fuse_direct_io(struct file *file, const char __user *buf,
815 size_t count, loff_t *ppos, int write);
816 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
818 long fuse_ioctl_common(struct file *file, unsigned int cmd,
819 unsigned long arg, unsigned int flags);
820 unsigned fuse_file_poll(struct file *file, poll_table *wait);
821 int fuse_dev_release(struct inode *inode, struct file *file);
823 void fuse_write_update_size(struct inode *inode, loff_t pos);
825 #endif /* _FS_FUSE_I_H */