/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2006 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/mount.h>
#include <linux/wait.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/backing-dev.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
/** Max number of pages that can be used in a single read request */
#define FUSE_MAX_PAGES_PER_REQ 32
/** Maximum number of outstanding background requests */
#define FUSE_MAX_BACKGROUND 12
/** Congestion starts at 75% of maximum */
#define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100)
/** Bias for fi->writectr, meaning new writepages must not be sent */
#define FUSE_NOWRITE INT_MIN
/** It could be as large as PATH_MAX, but would that have any uses? */
#define FUSE_NAME_MAX 1024
/** Number of dentries for each connection in the control filesystem */
#define FUSE_CTL_NUM_DENTRIES 3
/** 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)
/** List of active connections */
extern struct list_head fuse_conn_list;
/** Global mutex protecting fuse_conn_list and the control filesystem */
extern struct mutex fuse_mutex;
/** 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 */
u64 i_time;
/** The sticky bit in inode->i_mode may have been removed, so
preserve the original mode */
mode_t orig_i_mode;
/** Version of last attribute change */
u64 attr_version;
/** Files usable in writepage. Protected by fc->lock */
struct list_head write_files;
/** Writepages pending on truncate or fsync */
struct list_head queued_writes;
/** Number of sent writes, a negative bias (FUSE_NOWRITE)
* means more writes are blocked */
int writectr;
/** Waitq for writepage completion */
wait_queue_head_t page_waitq;
/** List of writepage requestst (pending or sent) */
struct list_head writepages;
};
/** FUSE specific file data */
struct fuse_file {
/** Request reserved for flush and release */
struct fuse_req *reserved_req;
/** File handle used by userspace */
u64 fh;
/** Refcount */
atomic_t count;
/** Entry on inode's write_files list */
struct list_head write_entry;
};
/** 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_WRITING,
FUSE_REQ_FINISHED
};
struct fuse_conn;
/**
* A request to the client
*/
struct fuse_req {
/** This can be on either pending processing or io lists in
fuse_conn */
struct list_head list;
/** Entry on the interrupts list */
struct list_head intr_entry;
/** refcount */
atomic_t count;
/** Unique ID for the interrupt request */
u64 intr_unique;
/*
* The following bitfields are either set once before the
* request is queued or setting/clearing them is protected by
* fuse_conn->lock
*/
/** True if the request has reply */
unsigned isreply:1;
/** Force sending of the request even if interrupted */
unsigned force:1;
/** The request was aborted */
unsigned aborted:1;
/** Request is sent in the background */
unsigned background:1;
/** The request has been interrupted */
unsigned interrupted:1;
/** Data is being copied to/from the request */
unsigned locked:1;
/** Request is counted as "waiting" */
unsigned waiting: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 {
struct fuse_release_in in;
struct vfsmount *vfsmount;
struct dentry *dentry;
} release;
struct fuse_init_in init_in;
struct fuse_init_out init_out;
struct {
struct fuse_read_in in;
u64 attr_ver;
} read;
struct {
struct fuse_write_in in;
struct fuse_write_out out;
} write;
struct fuse_lk_in lk_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;
/** File used in the request (or NULL) */
struct fuse_file *ff;
/** Inode used in the request or NULL */
struct inode *inode;
/** Link on fi->writepages */
struct list_head writepages_entry;
/** Request completion callback */
void (*end)(struct fuse_conn *, struct fuse_req *);
/** Request is stolen from fuse_file->reserved_req */
struct file *stolen_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 {
/** Lock protecting accessess to members of this structure */
spinlock_t lock;
/** Mutex protecting against directory alias creation */
struct mutex inst_mutex;
/** Refcount */
atomic_t 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;
/** The list of requests under I/O */
struct list_head io;
/** Number of requests currently in the background */
unsigned num_background;
/** Number of background requests currently queued for userspace */
unsigned active_background;
/** The list of background requests set aside for later queuing */
struct list_head bg_queue;
/** Pending interrupts */
struct list_head interrupts;
/** Flag indicating if connection is blocked. This will be
the case before the INIT reply is received, and if there
are too many outstading backgrounds requests */
int blocked;
/** waitq for blocked connection */
wait_queue_head_t blocked_waitq;
/** waitq for reserved requests */
wait_queue_head_t reserved_req_waitq;
/** The next unique request id */
u64 reqctr;
/** 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;
/** Connection successful. Only set in INIT */
unsigned conn_init : 1;
/** Do readpages asynchronously? Only set in INIT */
unsigned async_read : 1;
/** Do not send separate SETATTR request before open(O_TRUNC) */
unsigned atomic_o_trunc : 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;
/** Are file locking primitives not implemented by fs? */
unsigned no_lock : 1;
/** Is access not implemented by fs? */
unsigned no_access : 1;
/** Is create not implemented by fs? */
unsigned no_create : 1;
/** Is interrupt not implemented by fs? */
unsigned no_interrupt : 1;
/** Is bmap not implemented by fs? */
unsigned no_bmap : 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;
/** Entry on the fuse_conn_list */
struct list_head entry;
/** Device ID from super block */
dev_t dev;
/** Dentries in the control filesystem */
struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];
/** number of dentries used in the above array */
int ctl_ndents;
/** O_ASYNC requests */
struct fasync_struct *fasync;
/** Key for lock owner ID scrambling */
u32 scramble_key[4];
/** Reserved request for the DESTROY message */
struct fuse_req *destroy_req;
/** Version counter for attribute changes */
u64 attr_version;
};
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_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;
/**
* Get a filled in inode
*/
struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
int generation, struct fuse_attr *attr,
u64 attr_valid, u64 attr_version);
/**
* Send FORGET command
*/
void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
u64 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);
/** Fill in ff->reserved_req with a RELEASE request */
void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode);
/**
* 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,
u64 attr_valid, u64 attr_version);
void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
u64 attr_valid);
void fuse_truncate(struct address_space *mapping, loff_t offset);
/**
* Initialize the client device
*/
int fuse_dev_init(void);
/**
* Cleanup the client device
*/
void fuse_dev_cleanup(void);
int fuse_ctl_init(void);
void fuse_ctl_cleanup(void);
/**
* Allocate a request
*/
struct fuse_req *fuse_request_alloc(void);
struct fuse_req *fuse_request_alloc_nofs(void);
/**
* Free a request
*/
void fuse_request_free(struct fuse_req *req);
/**
* Get a request, may fail with -ENOMEM
*/
struct fuse_req *fuse_get_req(struct fuse_conn *fc);
/**
* Gets a requests for a file operation, always succeeds
*/
struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
/**
* Decrement reference count of a request. If count goes to zero free
* the request.
*/
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);
void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req);
/* Abort all requests */
void fuse_abort_conn(struct fuse_conn *fc);
/**
* Invalidate inode attributes
*/
void fuse_invalidate_attr(struct inode *inode);
/**
* Acquire reference to fuse_conn
*/
struct fuse_conn *fuse_conn_get(struct fuse_conn *fc);
/**
* Release reference to fuse_conn
*/
void fuse_conn_put(struct fuse_conn *fc);
/**
* Add connection to control filesystem
*/
int fuse_ctl_add_conn(struct fuse_conn *fc);
/**
* Remove connection from control filesystem
*/
void fuse_ctl_remove_conn(struct fuse_conn *fc);
/**
* Is file type valid?
*/
int fuse_valid_type(int m);
/**
* Is task allowed to perform filesystem operation?
*/
int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
int fuse_update_attributes(struct inode *inode, struct kstat *stat,
struct file *file, bool *refreshed);
void fuse_flush_writepages(struct inode *inode);
void fuse_set_nowrite(struct inode *inode);
void fuse_release_nowrite(struct inode *inode);
u64 fuse_get_attr_version(struct fuse_conn *fc);
