92 lines
3.5 KiB
C
92 lines
3.5 KiB
C
/*
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* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
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* The President and Fellows of Harvard College.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _FS_H_
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#define _FS_H_
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struct vnode; /* in vnode.h */
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/*
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* Abstract file system. (Or device accessible as a file.)
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*
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* fs_data is a pointer to filesystem-specific data.
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*/
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struct fs {
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void *fs_data;
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const struct fs_ops *fs_ops;
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};
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/*
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* Abstraction operations on a file system:
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*
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* fsop_sync - Flush all dirty buffers to disk.
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* fsop_getvolname - Return volume name of filesystem.
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* fsop_getroot - Return root vnode of filesystem.
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* fsop_unmount - Attempt unmount of filesystem.
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*
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* fsop_getvolname may return NULL on filesystem types that don't
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* support the concept of a volume name. The string returned is
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* assumed to point into the filesystem's private storage and live
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* until unmount time.
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*
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* If the volume name changes on the fly, there is no way at present
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* to make sure such changes don't cause name conflicts. So it probably
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* should be considered fixed.
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*
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* fsop_getroot should increment the refcount of the vnode returned.
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* It should not ever return NULL.
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*
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* If fsop_unmount returns an error, the filesystem stays mounted, and
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* consequently the struct fs instance should remain valid. On success,
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* however, the filesystem object and all storage associated with the
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* filesystem should have been discarded/released.
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*/
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struct fs_ops {
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int (*fsop_sync)(struct fs *);
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const char *(*fsop_getvolname)(struct fs *);
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int (*fsop_getroot)(struct fs *, struct vnode **);
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int (*fsop_unmount)(struct fs *);
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};
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/*
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* Macros to shorten the calling sequences.
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*/
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#define FSOP_SYNC(fs) ((fs)->fs_ops->fsop_sync(fs))
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#define FSOP_GETVOLNAME(fs) ((fs)->fs_ops->fsop_getvolname(fs))
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#define FSOP_GETROOT(fs, ret) ((fs)->fs_ops->fsop_getroot(fs, ret))
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#define FSOP_UNMOUNT(fs) ((fs)->fs_ops->fsop_unmount(fs))
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/* Initialization functions for builtin fake file systems. */
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void semfs_bootstrap(void);
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#endif /* _FS_H_ */
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