/* FUSE: Filesystem in Userspace Copyright (C) 2001-2005 Miklos Szeredi <miklos@szeredi.hu> This program can be distributed under the terms of the GNU GPL. See the file COPYING. */ #include <linux/fuse.h> #include <linux/fs.h> #include <linux/wait.h> #include <linux/list.h> #include <linux/spinlock.h> #include <linux/mm.h> #include <linux/backing-dev.h> #include <asm/semaphore.h> /** 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 /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem module will check permissions based on the file mode. Otherwise no permission checking is done in the kernel */ #define FUSE_DEFAULT_PERMISSIONS (1 << 0) /** If the FUSE_ALLOW_OTHER flag is given, then not only the user doing the mount will be allowed to access the filesystem */ #define FUSE_ALLOW_OTHER (1 << 1) /** FUSE inode */ struct fuse_inode { /** Inode data */ struct inode inode; /** Unique ID, which identifies the inode between userspace * and kernel */ u64 nodeid; /** Number of lookups on this inode */ u64 nlookup; /** The request used for sending the FORGET message */ struct fuse_req *forget_req; /** Time in jiffies until the file attributes are valid */ unsigned long i_time; }; /** FUSE specific file data */ struct fuse_file { /** Request reserved for flush and release */ struct fuse_req *release_req; /** File handle used by userspace */ u64 fh; }; /** 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; /** Entry on the background list */ struct list_head bg_entry; /** 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_forget_in forget_in; struct fuse_release_in release_in; 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 { /** Reference count */ int count; /** The user id for this mount */ uid_t user_id; /** The group id for this mount */ gid_t group_id; /** The fuse mount flags for this mount */ unsigned flags; /** Maximum read size */ unsigned max_read; /** Maximum write size */ unsigned max_write; /** 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; /** Requests put in the background (RELEASE or any other interrupted request) */ struct list_head background; /** 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; /** RW semaphore for exclusion with fuse_put_super() */ struct rw_semaphore sbput_sem; /** The list of unused requests */ struct list_head unused_list; /** The next unique request id */ u64 reqctr; /** Mount is active */ unsigned mounted : 1; /** Connection established */ unsigned connected : 1; /** Connection failed (version mismatch) */ unsigned conn_error : 1; /** Is fsync not implemented by fs? */ unsigned no_fsync : 1; /** Is fsyncdir not implemented by fs? */ unsigned no_fsyncdir : 1; /** Is flush not implemented by fs? */ unsigned no_flush : 1; /** Is setxattr not implemented by fs? */ unsigned no_setxattr : 1; /** Is getxattr not implemented by fs? */ unsigned no_getxattr : 1; /** Is listxattr not implemented by fs? */ unsigned no_listxattr : 1; /** Is removexattr not implemented by fs? */ unsigned no_removexattr : 1; /** Is access not implemented by fs? */ unsigned no_access : 1; /** Is create not implemented by fs? */ unsigned no_create : 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 * - background list 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; /** * Get a filled in inode */ struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid, int generation, struct fuse_attr *attr); /** * Send FORGET command */ void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req, unsigned long nodeid, u64 nlookup); /** * Send READ or READDIR request */ size_t fuse_send_read_common(struct fuse_req *req, struct file *file, struct inode *inode, loff_t pos, size_t count, int isdir); /** * Send OPEN or OPENDIR request */ int fuse_open_common(struct inode *inode, struct file *file, int isdir); struct fuse_file *fuse_file_alloc(void); void fuse_file_free(struct fuse_file *ff); void fuse_finish_open(struct inode *inode, struct file *file, struct fuse_file *ff, struct fuse_open_out *outarg); /** * Send a RELEASE request */ void fuse_send_release(struct fuse_conn *fc, struct fuse_file *ff, u64 nodeid, struct inode *inode, int flags, int isdir); /** * Send RELEASE or RELEASEDIR request */ int fuse_release_common(struct inode *inode, struct file *file, int isdir); /** * Send FSYNC or FSYNCDIR request */ int fuse_fsync_common(struct file *file, struct dentry *de, int datasync, int isdir); /** * Initialize file operations on a regular file */ void fuse_init_file_inode(struct inode *inode); /** * Initialize inode operations on regular files and special files */ void fuse_init_common(struct inode *inode); /** * Initialize inode and file operations on a directory */ void fuse_init_dir(struct inode *inode); /** * Initialize inode operations on a symlink */ void fuse_init_symlink(struct inode *inode); /** * Change attributes of an inode */ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr); /** * 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); /** * Decrement reference count of a request. If count goes to zero put * on unused list (preallocated) or free request (not preallocated). */ void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req); /** * Send a request (synchronous) */ void request_send(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); /** * Release inodes and file associated with background request */ void fuse_release_background(struct fuse_req *req); /** * Get the attributes of a file */ int fuse_do_getattr(struct inode *inode); /** * Invalidate inode attributes */ void fuse_invalidate_attr(struct inode *inode); /** * Send the INIT message */ void fuse_send_init(struct fuse_conn *fc);