/*
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
/** It could be as large as PATH_MAX, but would that have any uses? */
#define FUSE_NAME_MAX 1024
/** 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;
/*
* The following bitfields are not changed during the request
* processing
*/
/** 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];
};
/** The request state */
enum fuse_req_state {
FUSE_REQ_INIT = 0,
FUSE_REQ_PENDING,
FUSE_REQ_READING,
FUSE_REQ_SENT,
FUSE_REQ_FINISHED
};
struct fuse_conn;
/**
* A request to the client
*/
struct fuse_req {
/** This can be on either unused_list, pending processing or
io lists in fuse_conn */
struct list_head list;
/** Entry on the background list */
struct list_head bg_entry;
/** refcount */
atomic_t count;
/*
* The following bitfields are either set once before the
* request is queued or setting/clearing them is protected by
* fuse_lock
*/
/** 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;
/** State of the request */
enum fuse_req_state state;
/** 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 init_in;
struct fuse_init_out init_out;
struct fuse_read_in read_in;
} 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;
/** Request completion callback */
void (*end)(struct fuse_conn *, struct fuse_req *);
};
/**
* 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 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;
/** The list of requests under I/O */
struct list_head io;
/** 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;
/** Connection established, cleared on umount, connection
abort and device release */
unsigned connected;
/** Connection failed (version mismatch). Cannot race with
setting other bitfields since it is only set once in INIT
reply, before any other request, and never cleared */
unsigned conn_error : 1;
/** Do readpages asynchronously? Only set in INIT */
unsigned async_read : 1;
/*
* The following bitfields are only for optimization purposes
* and hence races in setting them will not cause malfunction
*/
/** 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;
/** The number of requests waiting for completion */
atomic_t num_waiting;
/** Negotiated minor version */
unsigned minor;
/** Backing dev info */
struct backing_dev_info bdi;
/** kobject */
struct kobject kobj;
};
static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
{
return sb->s_fs_info;
}
static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
{
return get_fuse_conn_super(inode->i_sb);
}
static inline struct fuse_conn *get_fuse_conn_kobj(struct kobject *obj)
{
return container_of(obj, struct fuse_conn, kobj);
}
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 const 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);
/**
* Initialize READ or READDIR request
*/
void fuse_read_fill(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count, int opcode);
/**
* 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);
/**
* 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);
/* Abort all requests */
void fuse_abort_conn(struct fuse_conn *fc);
/**
* Get the attributes of a file
*/
int fuse_do_getattr(struct inode *inode);
/**
* Invalidate inode attributes
*/
void fuse_invalidate_attr(struct inode *inode);
