/* FUSE: Filesystem in Userspace Copyright (C) 2001-2005 Miklos Szeredi This program can be distributed under the terms of the GNU GPL. See the file COPYING. */ #include #include #include #include #include #include #include #include /** Max number of pages that can be used in a single read request */ #define FUSE_MAX_PAGES_PER_REQ 32 /** If more requests are outstanding, then the operation will block */ #define FUSE_MAX_OUTSTANDING 10 /** FUSE inode */ struct fuse_inode { /** Inode data */ struct inode inode; /** Unique ID, which identifies the inode between userspace * and kernel */ u64 nodeid; /** Time in jiffies until the file attributes are valid */ unsigned long i_time; }; /** One input argument of a request */ struct fuse_in_arg { unsigned size; const void *value; }; /** The request input */ struct fuse_in { /** The request header */ struct fuse_in_header h; /** True if the data for the last argument is in req->pages */ unsigned argpages:1; /** Number of arguments */ unsigned numargs; /** Array of arguments */ struct fuse_in_arg args[3]; }; /** One output argument of a request */ struct fuse_arg { unsigned size; void *value; }; /** The request output */ struct fuse_out { /** Header returned from userspace */ struct fuse_out_header h; /** Last argument is variable length (can be shorter than arg->size) */ unsigned argvar:1; /** Last argument is a list of pages to copy data to */ unsigned argpages:1; /** Zero partially or not copied pages */ unsigned page_zeroing:1; /** Number or arguments */ unsigned numargs; /** Array of arguments */ struct fuse_arg args[3]; }; struct fuse_req; struct fuse_conn; /** * A request to the client */ struct fuse_req { /** This can be on either unused_list, pending or processing lists in fuse_conn */ struct list_head list; /** refcount */ atomic_t count; /** True if the request has reply */ unsigned isreply:1; /** The request is preallocated */ unsigned preallocated:1; /** The request was interrupted */ unsigned interrupted:1; /** Request is sent in the background */ unsigned background:1; /** Data is being copied to/from the request */ unsigned locked:1; /** Request has been sent to userspace */ unsigned sent:1; /** The request is finished */ unsigned finished:1; /** The request input */ struct fuse_in in; /** The request output */ struct fuse_out out; /** Used to wake up the task waiting for completion of request*/ wait_queue_head_t waitq; /** Data for asynchronous requests */ union { struct fuse_init_in_out init_in_out; } misc; /** page vector */ struct page *pages[FUSE_MAX_PAGES_PER_REQ]; /** number of pages in vector */ unsigned num_pages; /** offset of data on first page */ unsigned page_offset; /** Inode used in the request */ struct inode *inode; /** Second inode used in the request (or NULL) */ struct inode *inode2; /** File used in the request (or NULL) */ struct file *file; }; /** * A Fuse connection. * * This structure is created, when the filesystem is mounted, and is * destroyed, when the client device is closed and the filesystem is * unmounted. */ struct fuse_conn { /** The superblock of the mounted filesystem */ struct super_block *sb; /** The opened client device */ struct file *file; /** The user id for this mount */ uid_t user_id; /** Readers of the connection are waiting on this */ wait_queue_head_t waitq; /** The list of pending requests */ struct list_head pending; /** The list of requests being processed */ struct list_head processing; /** Controls the maximum number of outstanding requests */ struct semaphore outstanding_sem; /** This counts the number of outstanding requests if outstanding_sem would go negative */ unsigned outstanding_debt; /** The list of unused requests */ struct list_head unused_list; /** The next unique request id */ u64 reqctr; /** Connection failed (version mismatch) */ unsigned conn_error : 1; /** Backing dev info */ struct backing_dev_info bdi; }; static inline struct fuse_conn **get_fuse_conn_super_p(struct super_block *sb) { return (struct fuse_conn **) &sb->s_fs_info; } static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb) { return *get_fuse_conn_super_p(sb); } static inline struct fuse_conn *get_fuse_conn(struct inode *inode) { return get_fuse_conn_super(inode->i_sb); } static inline struct fuse_inode *get_fuse_inode(struct inode *inode) { return container_of(inode, struct fuse_inode, inode); } static inline u64 get_node_id(struct inode *inode) { return get_fuse_inode(inode)->nodeid; } /** Device operations */ extern struct file_operations fuse_dev_operations; /** * This is the single global spinlock which protects FUSE's structures * * The following data is protected by this lock: * * - the private_data field of the device file * - the s_fs_info field of the super block * - unused_list, pending, processing lists in fuse_conn * - the unique request ID counter reqctr in fuse_conn * - the sb (super_block) field in fuse_conn * - the file (device file) field in fuse_conn */ extern spinlock_t fuse_lock; /** * Check if the connection can be released, and if yes, then free the * connection structure */ void fuse_release_conn(struct fuse_conn *fc); /** * Initialize the client device */ int fuse_dev_init(void); /** * Cleanup the client device */ void fuse_dev_cleanup(void); /** * Allocate a request */ struct fuse_req *fuse_request_alloc(void); /** * Free a request */ void fuse_request_free(struct fuse_req *req); /** * Reinitialize a request, the preallocated flag is left unmodified */ void fuse_reset_request(struct fuse_req *req); /** * Reserve a preallocated request */ struct fuse_req *fuse_get_request(struct fuse_conn *fc); /** * Reserve a preallocated request, only interruptible by SIGKILL */ struct fuse_req *fuse_get_request_nonint(struct fuse_conn *fc); /** * Decrement reference count of a request. If count goes to zero put * on unused list (preallocated) or free reqest (not preallocated). */ void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req); /** * Send a request (synchronous, interruptible) */ void request_send(struct fuse_conn *fc, struct fuse_req *req); /** * Send a request (synchronous, non-interruptible except by SIGKILL) */ void request_send_nonint(struct fuse_conn *fc, struct fuse_req *req); /** * Send a request with no reply */ void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req); /** * Send a request in the background */ void request_send_background(struct fuse_conn *fc, struct fuse_req *req); /** * Send the INIT message */ void fuse_send_init(struct fuse_conn *fc);