1 /* $NetBSD: efs_extent.h,v 1.3 2007/07/04 19:24:09 rumble Exp $ */ 2 3 /* 4 * Copyright (c) 2006 Stephen M. Rumble <rumble@ephemeral.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 /* 20 * EFS extent descriptor format and sundry. 21 * 22 * See IRIX inode(4) 23 */ 24 25 #ifndef _FS_EFS_EFS_EXTENT_H_ 26 #define _FS_EFS_EFS_EXTENT_H_ 27 28 /* 29 * EFS on-disk extent descriptor (8 bytes) 30 * 31 * SGI smushed this structure's members into bit fields, but we have to 32 * be a little more portable. Therefore we use the efs_extent (see below) 33 * type for in-core manipulation and convert immediately to and from disk. 34 */ 35 struct efs_dextent { 36 union { 37 uint64_t ex_magic:8, /* magic number (always 0) */ 38 ex_bn:24, /* bb number in filesystem */ 39 ex_length:8, /* length of extent (in bb) */ 40 ex_offset:24; /* logical file offset (in bb) */ 41 uint8_t bytes[8]; 42 uint32_t words[2]; 43 } ex_muddle; 44 } __packed; 45 #define ex_bytes ex_muddle.bytes 46 #define ex_words ex_muddle.words 47 48 /* 49 * In-core, unsquished representation of an extent. 50 */ 51 struct efs_extent { 52 uint8_t ex_magic; 53 uint32_t ex_bn; /* NB: only 24 bits on disk */ 54 uint8_t ex_length; 55 uint32_t ex_offset; /* NB: only 24 bits on disk */ 56 }; 57 58 #define EFS_EXTENT_MAGIC 0 59 #define EFS_EXTENT_BN_MASK 0x00ffffff 60 #define EFS_EXTENT_OFFSET_MASK 0x00ffffff 61 62 #define EFS_EXTENTS_PER_BB (EFS_BB_SIZE / sizeof(struct efs_dextent)) 63 64 #endif /* !_FS_EFS_EFS_EXTENT_H_ */ 65