root/kern/include/fs.h

INCLUDED FROM

   1 /*
   2  * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
   3  *      The President and Fellows of Harvard College.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  30 #ifndef _FS_H_
  31 #define _FS_H_
  34 /*
  35  * Abstract filesystem. (Or device accessible as a file.)
  36  *
  37  * Operations:
  38  *
  39  *      fs_sync       - Flush all dirty buffers to disk.
  40  *      fs_getvolname - Return volume name of filesystem.
  41  *      fs_getroot    - Return root vnode of filesystem.
  42  *      fs_unmount    - Attempt unmount of filesystem.
  43  *
  44  * fs_getvolname may return NULL on filesystem types that don't
  45  * support the concept of a volume name. The string returned is
  46  * assumed to point into the filesystem's private storage and live
  47  * until unmount time.
  48  *
  49  * If the volume name changes on the fly, there is no way at present
  50  * to make sure such changes don't cause name conflicts. So it probably
  51  * should be considered fixed.
  52  *
  53  * fs_getroot should increment the refcount of the vnode returned.
  54  * It should not ever return NULL.
  55  *
  56  * If fs_unmount returns an error, the filesystem stays mounted, and
  57  * consequently the struct fs instance should remain valid. On success,
  58  * however, the filesystem object and all storage associated with the
  59  * filesystem should have been discarded/released.
  60  *
  61  * fs_data is a pointer to filesystem-specific data.
  62  */
  64 struct fs {
  65         int           (*fs_sync)(struct fs *);
  66         const char   *(*fs_getvolname)(struct fs *);
  67         struct vnode *(*fs_getroot)(struct fs *);
  68         int           (*fs_unmount)(struct fs *);
  70         void *fs_data;
  71 };
  73 /*
  74  * Macros to shorten the calling sequences.
  75  */
  76 #define FSOP_SYNC(fs)        ((fs)->fs_sync(fs))
  77 #define FSOP_GETVOLNAME(fs)  ((fs)->fs_getvolname(fs))
  78 #define FSOP_GETROOT(fs)     ((fs)->fs_getroot(fs))
  79 #define FSOP_UNMOUNT(fs)     ((fs)->fs_unmount(fs))
  82 #endif /* _FS_H_ */