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fuse_i.h

/*
  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>

/** 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)

/** 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 */
00050 struct fuse_inode {
      /** Inode data */
00052       struct inode inode;

      /** Unique ID, which identifies the inode between userspace
       * and kernel */
00056       u64 nodeid;

      /** Number of lookups on this inode */
00059       u64 nlookup;

      /** The request used for sending the FORGET message */
00062       struct fuse_req *forget_req;

      /** Time in jiffies until the file attributes are valid */
00065       u64 i_time;

      /** The sticky bit in inode->i_mode may have been removed, so
          preserve the original mode */
00069       mode_t orig_i_mode;

      /** Version of last attribute change */
00072       u64 attr_version;

      /** Files usable in writepage.  Protected by fc->lock */
00075       struct list_head write_files;
};

/** FUSE specific file data */
00079 struct fuse_file {
      /** Request reserved for flush and release */
00081       struct fuse_req *reserved_req;

      /** File handle used by userspace */
00084       u64 fh;

      /** Refcount */
00087       atomic_t count;

      /** Entry on inode's write_files list */
00090       struct list_head write_entry;
};

/** One input argument of a request */
00094 struct fuse_in_arg {
      unsigned size;
      const void *value;
};

/** The request input */
00100 struct fuse_in {
      /** The request header */
00102       struct fuse_in_header h;

      /** True if the data for the last argument is in req->pages */
00105       unsigned argpages:1;

      /** Number of arguments */
00108       unsigned numargs;

      /** Array of arguments */
00111       struct fuse_in_arg args[3];
};

/** One output argument of a request */
00115 struct fuse_arg {
      unsigned size;
      void *value;
};

/** The request output */
00121 struct fuse_out {
      /** Header returned from userspace */
00123       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) */
00132       unsigned argvar:1;

      /** Last argument is a list of pages to copy data to */
00135       unsigned argpages:1;

      /** Zero partially or not copied pages */
00138       unsigned page_zeroing:1;

      /** Number or arguments */
00141       unsigned numargs;

      /** Array of arguments */
00144       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
 */
00162 struct fuse_req {
      /** This can be on either pending processing or io lists in
          fuse_conn */
00165       struct list_head list;

      /** Entry on the interrupts list  */
00168       struct list_head intr_entry;

      /** refcount */
00171       atomic_t count;

      /** Unique ID for the interrupt request */
00174       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 */
00183       unsigned isreply:1;

      /** Force sending of the request even if interrupted */
00186       unsigned force:1;

      /** The request was aborted */
00189       unsigned aborted:1;

      /** Request is sent in the background */
00192       unsigned background:1;

      /** The request has been interrupted */
00195       unsigned interrupted:1;

      /** Data is being copied to/from the request */
00198       unsigned locked:1;

      /** Request is counted as "waiting" */
00201       unsigned waiting:1;

      /** State of the request */
00204       enum fuse_req_state state;

      /** The request input */
00207       struct fuse_in in;

      /** The request output */
00210       struct fuse_out out;

      /** Used to wake up the task waiting for completion of request*/
00213       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;
            struct {
                  struct fuse_write_in in;
                  struct fuse_write_out out;
            } write;
            struct fuse_lk_in lk_in;
      } misc;

      /** page vector */
00230       struct page *pages[FUSE_MAX_PAGES_PER_REQ];

      /** number of pages in vector */
00233       unsigned num_pages;

      /** offset of data on first page */
00236       unsigned page_offset;

      /** File used in the request (or NULL) */
00239       struct fuse_file *ff;

      /** vfsmount used in release */
00242       struct vfsmount *vfsmount;

      /** dentry used in release */
00245       struct dentry *dentry;

      /** Request completion callback */
      void (*end)(struct fuse_conn *, struct fuse_req *);

      /** Request is stolen from fuse_file->reserved_req */
00251       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.
 */
00261 struct fuse_conn {
      /** Lock protecting accessess to  members of this structure */
00263       spinlock_t lock;

      /** Mutex protecting against directory alias creation */
00266       struct mutex inst_mutex;

      /** Refcount */
00269       atomic_t count;

      /** The user id for this mount */
00272       uid_t user_id;

      /** The group id for this mount */
00275       gid_t group_id;

      /** The fuse mount flags for this mount */
00278       unsigned flags;

      /** Maximum read size */
00281       unsigned max_read;

      /** Maximum write size */
00284       unsigned max_write;

      /** Readers of the connection are waiting on this */
00287       wait_queue_head_t waitq;

      /** The list of pending requests */
00290       struct list_head pending;

      /** The list of requests being processed */
00293       struct list_head processing;

      /** The list of requests under I/O */
00296       struct list_head io;

      /** Number of requests currently in the background */
00299       unsigned num_background;

      /** Pending interrupts */
00302       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 */
00307       int blocked;

      /** waitq for blocked connection */
00310       wait_queue_head_t blocked_waitq;

      /** waitq for reserved requests */
00313       wait_queue_head_t reserved_req_waitq;

      /** The next unique request id */
00316       u64 reqctr;

      /** Connection established, cleared on umount, connection
          abort and device release */
00320       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 */
00325       unsigned conn_error : 1;

      /** Connection successful.  Only set in INIT */
00328       unsigned conn_init : 1;

      /** Do readpages asynchronously?  Only set in INIT */
00331       unsigned async_read : 1;

      /** Do not send separate SETATTR request before open(O_TRUNC)  */
00334       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? */
00342       unsigned no_fsync : 1;

      /** Is fsyncdir not implemented by fs? */
00345       unsigned no_fsyncdir : 1;

      /** Is flush not implemented by fs? */
00348       unsigned no_flush : 1;

      /** Is setxattr not implemented by fs? */
00351       unsigned no_setxattr : 1;

      /** Is getxattr not implemented by fs? */
00354       unsigned no_getxattr : 1;

      /** Is listxattr not implemented by fs? */
00357       unsigned no_listxattr : 1;

      /** Is removexattr not implemented by fs? */
00360       unsigned no_removexattr : 1;

      /** Are file locking primitives not implemented by fs? */
00363       unsigned no_lock : 1;

      /** Is access not implemented by fs? */
00366       unsigned no_access : 1;

      /** Is create not implemented by fs? */
00369       unsigned no_create : 1;

      /** Is interrupt not implemented by fs? */
00372       unsigned no_interrupt : 1;

      /** Is bmap not implemented by fs? */
00375       unsigned no_bmap : 1;

      /** The number of requests waiting for completion */
00378       atomic_t num_waiting;

      /** Negotiated minor version */
00381       unsigned minor;

      /** Backing dev info */
00384       struct backing_dev_info bdi;

      /** Entry on the fuse_conn_list */
00387       struct list_head entry;

      /** Unique ID */
00390       u64 id;

      /** Dentries in the control filesystem */
00393       struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES];

      /** number of dentries used in the above array */
00396       int ctl_ndents;

      /** O_ASYNC requests */
00399       struct fasync_struct *fasync;

      /** Key for lock owner ID scrambling */
00402       u32 scramble_key[4];

      /** Reserved request for the DESTROY message */
00405       struct fuse_req *destroy_req;

      /** Version counter for attribute changes */
00408       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, unsigned long 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,
                  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);

/** 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);

/**
 * 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);

/**
 * 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);

/* 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);

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