2 * modified for EXT2FS support in Lites 1.1
4 * Aug 1995, Godmar Back (gback@cs.utah.edu)
5 * University of Utah, Department of Computer Science
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39 * @(#)fs.h 8.7 (Berkeley) 4/19/94
40 * $FreeBSD: src/sys/gnu/ext2fs/fs.h,v 1.5.2.1 2000/11/11 13:12:45 bde Exp $
44 * Each disk drive contains some number of file systems.
45 * A file system consists of a number of cylinder groups.
46 * Each cylinder group has inodes and data.
48 * A file system is described by its super-block, which in turn
49 * describes the cylinder groups. The super-block is critical
50 * data and is replicated in each cylinder group to protect against
51 * catastrophic loss. This is done at `newfs' time and the critical
52 * super-block data does not change, so the copies need not be
53 * referenced further unless disaster strikes.
55 * The first boot and super blocks are given in absolute disk addresses.
56 * The byte-offset forms are preferred, as they don't imply a sector size.
60 #define BBOFF ((off_t)(0))
61 #define SBOFF ((off_t)(BBOFF + BBSIZE))
62 #define BBLOCK ((daddr_t)(0))
63 #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
66 * The path name on which the file system is mounted is maintained
67 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
68 * the super block for this name.
73 * Macros for access to superblock array structures
77 * Convert cylinder group to base address of its global summary info.
79 #define fs_cs(fs, cgindx) (((struct ext2_group_desc *) \
80 (fs->s_group_desc[cgindx / EXT2_DESC_PER_BLOCK(fs)]->b_data)) \
81 [cgindx % EXT2_DESC_PER_BLOCK(fs)])
84 * Turn file system block numbers into disk block addresses.
85 * This maps file system blocks to device size blocks.
87 #define fsbtodb(fs, b) ((b) << ((fs)->s_fsbtodb))
88 #define dbtofsb(fs, b) ((b) >> ((fs)->s_fsbtodb))
90 /* get group containing inode */
91 #define ino_to_cg(fs, x) (((x) - 1) / EXT2_INODES_PER_GROUP(fs))
93 /* get block containing inode from its number x */
94 #define ino_to_fsba(fs, x) fs_cs(fs, ino_to_cg(fs, x)).bg_inode_table + \
95 (((x)-1) % EXT2_INODES_PER_GROUP(fs))/EXT2_INODES_PER_BLOCK(fs)
97 /* get offset for inode in block */
98 #define ino_to_fsbo(fs, x) ((x-1) % EXT2_INODES_PER_BLOCK(fs))
101 * Give cylinder group number for a file system block.
102 * Give cylinder group block number for a file system block.
104 #define dtog(fs, d) (((d) - fs->s_es->s_first_data_block) / \
105 EXT2_BLOCKS_PER_GROUP(fs))
106 #define dtogd(fs, d) (((d) - fs->s_es->s_first_data_block) % \
107 EXT2_BLOCKS_PER_GROUP(fs))
110 * The following macros optimize certain frequently calculated
111 * quantities by using shifts and masks in place of divisions
112 * modulos and multiplications.
114 #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \
115 ((loc) & (fs)->s_qbmask)
117 #define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \
118 ((blk) << (fs->s_bshift))
120 #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \
121 ((loc) >> (fs->s_bshift))
123 /* no fragments -> logical block number equal # of frags */
124 #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \
125 ((loc) >> (fs->s_bshift))
127 #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
128 roundup(size, fs->s_frag_size)
129 /* was (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask) */
132 * Determining the size of a file block in the file system.
135 #define blksize(fs, ip, lbn) ((fs)->s_frag_size)
138 * INOPB is the number of inodes in a secondary storage block.
140 #define INOPB(fs) EXT2_INODES_PER_BLOCK(fs)
143 * NINDIR is the number of indirects in a file system block.
145 #define NINDIR(fs) (EXT2_ADDR_PER_BLOCK(fs))
147 extern int inside[], around[];
148 extern u_char *fragtbl[];
150 /* a few remarks about superblock locking/unlocking
151 * Linux provides special routines for doing so
152 * I haven't figured out yet what BSD does
153 * I think I'll try a VOP_LOCK/VOP_UNLOCK on the device vnode
155 #define DEVVP(inode) (VFSTOUFS(ITOV(inode)->v_mount)->um_devvp)
156 #define lock_super(devvp) vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY, curproc)
157 #define unlock_super(devvp) VOP_UNLOCK(devvp, 0, curproc)
160 * To lock a buffer, set the B_LOCKED flag and then brelse() it. To unlock,
161 * reset the B_LOCKED flag and brelse() the buffer back on the LRU list
163 #define LCK_BUF(bp) { \
166 (bp)->b_flags |= B_LOCKED; \
171 #define ULCK_BUF(bp) { \
175 flags = (bp)->b_flags; \
176 (bp)->b_flags &= ~(B_DIRTY | B_LOCKED); \
177 BUF_LOCK(bp, LK_EXCLUSIVE); \
180 if (flags & B_DIRTY) \