65 lines
2.0 KiB
C
65 lines
2.0 KiB
C
/* $NetBSD: efs_extent.h,v 1.3 2007/07/04 19:24:09 rumble Exp $ */
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/*
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* Copyright (c) 2006 Stephen M. Rumble <rumble@ephemeral.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* EFS extent descriptor format and sundry.
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*
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* See IRIX inode(4)
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*/
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#ifndef _FS_EFS_EFS_EXTENT_H_
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#define _FS_EFS_EFS_EXTENT_H_
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/*
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* EFS on-disk extent descriptor (8 bytes)
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*
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* SGI smushed this structure's members into bit fields, but we have to
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* be a little more portable. Therefore we use the efs_extent (see below)
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* type for in-core manipulation and convert immediately to and from disk.
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*/
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struct efs_dextent {
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union {
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uint64_t ex_magic:8, /* magic number (always 0) */
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ex_bn:24, /* bb number in filesystem */
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ex_length:8, /* length of extent (in bb) */
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ex_offset:24; /* logical file offset (in bb) */
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uint8_t bytes[8];
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uint32_t words[2];
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} ex_muddle;
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} __packed;
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#define ex_bytes ex_muddle.bytes
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#define ex_words ex_muddle.words
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/*
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* In-core, unsquished representation of an extent.
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*/
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struct efs_extent {
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uint8_t ex_magic;
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uint32_t ex_bn; /* NB: only 24 bits on disk */
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uint8_t ex_length;
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uint32_t ex_offset; /* NB: only 24 bits on disk */
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};
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#define EFS_EXTENT_MAGIC 0
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#define EFS_EXTENT_BN_MASK 0x00ffffff
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#define EFS_EXTENT_OFFSET_MASK 0x00ffffff
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#define EFS_EXTENTS_PER_BB (EFS_BB_SIZE / sizeof(struct efs_dextent))
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#endif /* !_FS_EFS_EFS_EXTENT_H_ */
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