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 block groups.
46 * Each block group has inodes and data.
48 * A file system is described by its super-block, which in turn
49 * describes the block groups. The super-block is critical
50 * data and is replicated in each block 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.
59 #ifndef _LINUX_EXT2_FS_FS
60 #define _LINUX_EXT2_FS_FS
64 #define BBOFF ((off_t)(0))
65 #define SBOFF ((off_t)(BBOFF + BBSIZE))
66 #define BBLOCK ((daddr_t)(0))
67 #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
70 * The path name on which the file system is mounted is maintained
71 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
72 * the super block for this name.
77 * Macros for access to superblock array structures
81 * Convert block group to base address of its global summary info.
83 #define fs_cs(fs, cgindx) (((struct ext2_group_desc *) \
84 (fs->s_group_desc[cgindx / EXT2_DESC_PER_BLOCK(fs)]->b_data)) \
85 [cgindx % EXT2_DESC_PER_BLOCK(fs)])
88 * Turn file system block numbers into disk block addresses.
89 * This maps file system blocks to device size blocks.
91 #define fsbtodb(fs, b) ((b) << ((fs)->s_fsbtodb))
92 #define dbtofsb(fs, b) ((b) >> ((fs)->s_fsbtodb))
94 /* get group containing inode */
95 #define ino_to_cg(fs, x) (((x) - 1) / EXT2_INODES_PER_GROUP(fs))
97 /* get block containing inode from its number x */
98 #define ino_to_fsba(fs, x) (fs_cs(fs, ino_to_cg(fs, x)).bg_inode_table + \
99 (((x)-1) % EXT2_INODES_PER_GROUP(fs))/EXT2_INODES_PER_BLOCK(fs))
101 /* get offset for inode in block */
102 #define ino_to_fsbo(fs, x) ((x-1) % EXT2_INODES_PER_BLOCK(fs))
105 * Give block group number for a file system block.
106 * Give block group block number for a file system block.
108 #define dtog(fs, d) (((d) - fs->s_es->s_first_data_block) / \
109 EXT2_BLOCKS_PER_GROUP(fs))
110 #define dtogd(fs, d) (((d) - fs->s_es->s_first_data_block) % \
111 EXT2_BLOCKS_PER_GROUP(fs))
114 * The following macros optimize certain frequently calculated
115 * quantities by using shifts and masks in place of divisions
116 * modulos and multiplications.
118 #define blkoff(fs, loc) /* calculates (loc % fs->fs_bsize) */ \
119 ((loc) & (fs)->s_qbmask)
121 #define lblktosize(fs, blk) /* calculates (blk * fs->fs_bsize) */ \
122 ((blk) << (fs->s_bshift))
125 * Used when converting logical blocks to offsets for getblk, bread,
128 #define lblktodoff(fs, blk) /* calculates (blk * fs->fs_bsize) */ \
129 ((off_t)(blk) << (fs)->s_bshift)
130 #define fsbtodoff(fs, blk) /* calculates (blk * fs->fs_fsize) */ \
131 ((off_t)(blk) * (fs)->s_frag_size)
132 #define dofftofsb(fs, blk) /* calculates blk / fs->fs_fsize */ \
133 ((daddr_t)((blk) / (fs)->s_frag_size))
134 #define dbtodoff(fs, b) /* calculates diskblk * sectorsize */ \
135 ((off_t)(b) * ((fs)->s_frag_size >> (fs)->s_fsbtodb))
137 #define lblkno(fs, loc) /* calculates (loc / fs->fs_bsize) */ \
138 ((loc) >> (fs->s_bshift))
140 /* no fragments -> logical block number equal # of frags */
141 #define numfrags(fs, loc) /* calculates (loc / fs->fs_fsize) */ \
142 ((loc) >> (fs->s_bshift))
144 #define fragroundup(fs, size) /* calculates roundup(size, fs->fs_fsize) */ \
145 roundup(size, fs->s_frag_size)
146 /* was (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask) */
149 * Determining the size of a file block in the file system.
152 #define blksize(fs, ip, lbn) ((fs)->s_frag_size)
155 * INOPB is the number of inodes in a secondary storage block.
157 #define INOPB(fs) EXT2_INODES_PER_BLOCK(fs)
160 * NINDIR is the number of indirects in a file system block.
162 #define NINDIR(fs) (EXT2_ADDR_PER_BLOCK(fs))
164 extern int inside[], around[];
165 extern u_char *fragtbl[];
167 /* a few remarks about superblock locking/unlocking
168 * Linux provides special routines for doing so
169 * I haven't figured out yet what BSD does
170 * I think I'll try a vn_lock/vn_unlock on the device vnode
172 #define DEVVP(inode) (VFSTOEXT2(ITOV(inode)->v_mount)->um_devvp)
173 #define lock_super(devvp) \
174 vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY | LK_FAILRECLAIM)
175 #define unlock_super(devvp) vn_unlock(devvp)
178 * To lock a buffer, set the B_LOCKED flag and then brelse() it. To unlock,
179 * reset the B_LOCKED flag and brelse() the buffer back on the LRU list
181 #define LCK_BUF(bp) { \
183 (bp)->b_flags |= B_LOCKED; \
188 #define ULCK_BUF(bp) { \
191 flags = (bp)->b_flags; \
192 (bp)->b_flags &= ~(B_DIRTY | B_LOCKED); \
193 BUF_LOCK(bp, LK_EXCLUSIVE); \
196 if (flags & B_DIRTY) \
202 #endif /* _LINUX_EXT2_FS_FS */