611 lines
17 KiB
C
611 lines
17 KiB
C
/*-
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* modified for Lites 1.1
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*
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* Aug 1995, Godmar Back (gback@cs.utah.edu)
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* University of Utah, Department of Computer Science
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*
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* $FreeBSD$
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*/
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/*-
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* linux/fs/ext2/balloc.c
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*
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* Copyright (C) 1992, 1993, 1994, 1995
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* Remy Card (card@masi.ibp.fr)
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* Laboratoire MASI - Institut Blaise Pascal
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* Universite Pierre et Marie Curie (Paris VI)
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*
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* Enhanced block allocation by Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
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*/
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/*
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* The free blocks are managed by bitmaps. A file system contains several
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* blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
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* block for inodes, N blocks for the inode table and data blocks.
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*
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* The file system contains group descriptors which are located after the
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* super block. Each descriptor contains the number of the bitmap block and
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* the free blocks count in the block. The descriptors are loaded in memory
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* when a file system is mounted (see ext2_read_super).
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bio.h>
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#include <sys/buf.h>
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#include <sys/mount.h>
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#include <sys/vnode.h>
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#include <gnu/ext2fs/inode.h>
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#include <gnu/ext2fs/ext2_mount.h>
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#include <gnu/ext2fs/ext2_extern.h>
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#include <gnu/ext2fs/ext2_fs.h>
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#include <gnu/ext2fs/ext2_fs_sb.h>
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#include <gnu/ext2fs/fs.h>
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#ifdef __i386__
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#include <gnu/ext2fs/i386-bitops.h>
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#else
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#include <gnu/ext2fs/ext2_bitops.h>
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#endif
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#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
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/* got rid of get_group_desc since it can already be found in
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* ext2_linux_ialloc.c
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*/
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static void read_block_bitmap (struct mount * mp,
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unsigned int block_group,
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unsigned long bitmap_nr)
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{
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struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
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struct ext2_group_desc * gdp;
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struct buffer_head * bh;
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int error;
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gdp = get_group_desc (mp, block_group, NULL);
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if ((error = bread (VFSTOEXT2(mp)->um_devvp,
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fsbtodb(sb, gdp->bg_block_bitmap),sb->s_blocksize, NOCRED, &bh)) != 0)
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panic ( "read_block_bitmap: "
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"Cannot read block bitmap - "
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"block_group = %d, block_bitmap = %lu",
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block_group, (unsigned long) gdp->bg_block_bitmap);
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sb->s_block_bitmap_number[bitmap_nr] = block_group;
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sb->s_block_bitmap[bitmap_nr] = bh;
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LCK_BUF(bh)
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}
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/*
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* load_block_bitmap loads the block bitmap for a blocks group
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*
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* It maintains a cache for the last bitmaps loaded. This cache is managed
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* with a LRU algorithm.
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*
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* Notes:
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* 1/ There is one cache per mounted file system.
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* 2/ If the file system contains less than EXT2_MAX_GROUP_LOADED groups,
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* this function reads the bitmap without maintaining a LRU cache.
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*/
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static int load__block_bitmap (struct mount * mp,
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unsigned int block_group)
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{
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int i, j;
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struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
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unsigned long block_bitmap_number;
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struct buffer_head * block_bitmap;
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if (block_group >= sb->s_groups_count)
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panic ( "load_block_bitmap: "
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"block_group >= groups_count - "
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"block_group = %d, groups_count = %lu",
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block_group, sb->s_groups_count);
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if (sb->s_groups_count <= EXT2_MAX_GROUP_LOADED) {
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if (sb->s_block_bitmap[block_group]) {
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if (sb->s_block_bitmap_number[block_group] !=
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block_group)
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panic ( "load_block_bitmap: "
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"block_group != block_bitmap_number");
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else
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return block_group;
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} else {
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read_block_bitmap (mp, block_group, block_group);
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return block_group;
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}
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}
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for (i = 0; i < sb->s_loaded_block_bitmaps &&
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sb->s_block_bitmap_number[i] != block_group; i++)
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;
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if (i < sb->s_loaded_block_bitmaps &&
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sb->s_block_bitmap_number[i] == block_group) {
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block_bitmap_number = sb->s_block_bitmap_number[i];
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block_bitmap = sb->s_block_bitmap[i];
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for (j = i; j > 0; j--) {
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sb->s_block_bitmap_number[j] =
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sb->s_block_bitmap_number[j - 1];
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sb->s_block_bitmap[j] =
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sb->s_block_bitmap[j - 1];
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}
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sb->s_block_bitmap_number[0] = block_bitmap_number;
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sb->s_block_bitmap[0] = block_bitmap;
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} else {
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if (sb->s_loaded_block_bitmaps < EXT2_MAX_GROUP_LOADED)
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sb->s_loaded_block_bitmaps++;
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else
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ULCK_BUF(sb->s_block_bitmap[EXT2_MAX_GROUP_LOADED - 1])
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for (j = sb->s_loaded_block_bitmaps - 1; j > 0; j--) {
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sb->s_block_bitmap_number[j] =
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sb->s_block_bitmap_number[j - 1];
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sb->s_block_bitmap[j] =
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sb->s_block_bitmap[j - 1];
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}
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read_block_bitmap (mp, block_group, 0);
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}
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return 0;
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}
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static __inline int load_block_bitmap (struct mount * mp,
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unsigned int block_group)
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{
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struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
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if (sb->s_loaded_block_bitmaps > 0 &&
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sb->s_block_bitmap_number[0] == block_group)
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return 0;
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if (sb->s_groups_count <= EXT2_MAX_GROUP_LOADED &&
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sb->s_block_bitmap_number[block_group] == block_group &&
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sb->s_block_bitmap[block_group])
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return block_group;
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return load__block_bitmap (mp, block_group);
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}
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void ext2_free_blocks (struct mount * mp, unsigned long block,
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unsigned long count)
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{
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struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
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struct buffer_head * bh;
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struct buffer_head * bh2;
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unsigned long block_group;
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unsigned long bit;
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unsigned long i;
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int bitmap_nr;
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struct ext2_group_desc * gdp;
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struct ext2_super_block * es;
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if (!sb) {
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printf ("ext2_free_blocks: nonexistent device");
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return;
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}
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es = sb->s_es;
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lock_super (VFSTOEXT2(mp)->um_devvp);
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if (block < es->s_first_data_block ||
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(block + count) > es->s_blocks_count) {
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printf ( "ext2_free_blocks: "
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"Freeing blocks not in datazone - "
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"block = %lu, count = %lu", block, count);
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unlock_super (VFSTOEXT2(mp)->um_devvp);
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return;
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}
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ext2_debug ("freeing blocks %lu to %lu\n", block, block+count-1);
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block_group = (block - es->s_first_data_block) /
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EXT2_BLOCKS_PER_GROUP(sb);
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bit = (block - es->s_first_data_block) % EXT2_BLOCKS_PER_GROUP(sb);
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if (bit + count > EXT2_BLOCKS_PER_GROUP(sb))
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panic ( "ext2_free_blocks: "
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"Freeing blocks across group boundary - "
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"Block = %lu, count = %lu",
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block, count);
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bitmap_nr = load_block_bitmap (mp, block_group);
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bh = sb->s_block_bitmap[bitmap_nr];
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gdp = get_group_desc (mp, block_group, &bh2);
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if (/* test_opt (sb, CHECK_STRICT) && assume always strict ! */
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(in_range (gdp->bg_block_bitmap, block, count) ||
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in_range (gdp->bg_inode_bitmap, block, count) ||
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in_range (block, gdp->bg_inode_table,
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sb->s_itb_per_group) ||
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in_range (block + count - 1, gdp->bg_inode_table,
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sb->s_itb_per_group)))
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panic ( "ext2_free_blocks: "
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"Freeing blocks in system zones - "
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"Block = %lu, count = %lu",
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block, count);
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for (i = 0; i < count; i++) {
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if (!clear_bit (bit + i, bh->b_data))
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printf ("ext2_free_blocks: "
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"bit already cleared for block %lu",
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block);
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else {
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gdp->bg_free_blocks_count++;
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es->s_free_blocks_count++;
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}
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}
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mark_buffer_dirty(bh2);
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mark_buffer_dirty(bh);
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/****
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if (sb->s_flags & MS_SYNCHRONOUS) {
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ll_rw_block (WRITE, 1, &bh);
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wait_on_buffer (bh);
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}
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****/
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sb->s_dirt = 1;
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unlock_super (VFSTOEXT2(mp)->um_devvp);
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return;
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}
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/*
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* ext2_new_block uses a goal block to assist allocation. If the goal is
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* free, or there is a free block within 32 blocks of the goal, that block
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* is allocated. Otherwise a forward search is made for a free block; within
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* each block group the search first looks for an entire free byte in the block
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* bitmap, and then for any free bit if that fails.
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*/
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int ext2_new_block (struct mount * mp, unsigned long goal,
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u_int32_t * prealloc_count,
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u_int32_t * prealloc_block)
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{
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struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
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struct buffer_head * bh;
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struct buffer_head * bh2;
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char * p, * r;
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int i, j, k, tmp;
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int bitmap_nr;
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struct ext2_group_desc * gdp;
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struct ext2_super_block * es;
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#ifdef EXT2FS_DEBUG
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static int goal_hits = 0, goal_attempts = 0;
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#endif
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if (!sb) {
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printf ("ext2_new_block: nonexistent device");
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return 0;
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}
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es = sb->s_es;
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lock_super (VFSTOEXT2(mp)->um_devvp);
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ext2_debug ("goal=%lu.\n", goal);
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repeat:
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/*
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* First, test whether the goal block is free.
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*/
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if (goal < es->s_first_data_block || goal >= es->s_blocks_count)
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goal = es->s_first_data_block;
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i = (goal - es->s_first_data_block) / EXT2_BLOCKS_PER_GROUP(sb);
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gdp = get_group_desc (mp, i, &bh2);
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if (gdp->bg_free_blocks_count > 0) {
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j = ((goal - es->s_first_data_block) % EXT2_BLOCKS_PER_GROUP(sb));
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#ifdef EXT2FS_DEBUG
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if (j)
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goal_attempts++;
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#endif
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bitmap_nr = load_block_bitmap (mp, i);
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bh = sb->s_block_bitmap[bitmap_nr];
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ext2_debug ("goal is at %d:%d.\n", i, j);
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if (!test_bit(j, bh->b_data)) {
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#ifdef EXT2FS_DEBUG
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goal_hits++;
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ext2_debug ("goal bit allocated.\n");
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#endif
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goto got_block;
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}
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if (j) {
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/*
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* The goal was occupied; search forward for a free
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* block within the next XX blocks.
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*
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* end_goal is more or less random, but it has to be
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* less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
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* next 64-bit boundary is simple..
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*/
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int end_goal = (j + 63) & ~63;
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j = find_next_zero_bit(bh->b_data, end_goal, j);
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if (j < end_goal)
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goto got_block;
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}
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ext2_debug ("Bit not found near goal\n");
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/*
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* There has been no free block found in the near vicinity
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* of the goal: do a search forward through the block groups,
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* searching in each group first for an entire free byte in
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* the bitmap and then for any free bit.
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*
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* Search first in the remainder of the current group; then,
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* cyclicly search through the rest of the groups.
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*/
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p = ((char *) bh->b_data) + (j >> 3);
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r = memscan(p, 0, (EXT2_BLOCKS_PER_GROUP(sb) - j + 7) >> 3);
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k = (r - ((char *) bh->b_data)) << 3;
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if (k < EXT2_BLOCKS_PER_GROUP(sb)) {
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j = k;
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goto search_back;
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}
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k = find_next_zero_bit ((unsigned long *) bh->b_data,
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EXT2_BLOCKS_PER_GROUP(sb),
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j);
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if (k < EXT2_BLOCKS_PER_GROUP(sb)) {
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j = k;
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goto got_block;
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}
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}
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ext2_debug ("Bit not found in block group %d.\n", i);
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/*
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* Now search the rest of the groups. We assume that
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* i and gdp correctly point to the last group visited.
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*/
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for (k = 0; k < sb->s_groups_count; k++) {
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i++;
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if (i >= sb->s_groups_count)
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i = 0;
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gdp = get_group_desc (mp, i, &bh2);
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if (gdp->bg_free_blocks_count > 0)
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break;
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}
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if (k >= sb->s_groups_count) {
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unlock_super (VFSTOEXT2(mp)->um_devvp);
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return 0;
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}
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bitmap_nr = load_block_bitmap (mp, i);
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bh = sb->s_block_bitmap[bitmap_nr];
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r = memscan(bh->b_data, 0, EXT2_BLOCKS_PER_GROUP(sb) >> 3);
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j = (r - bh->b_data) << 3;
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if (j < EXT2_BLOCKS_PER_GROUP(sb))
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goto search_back;
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else
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j = find_first_zero_bit ((unsigned long *) bh->b_data,
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EXT2_BLOCKS_PER_GROUP(sb));
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if (j >= EXT2_BLOCKS_PER_GROUP(sb)) {
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printf ( "ext2_new_block: "
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"Free blocks count corrupted for block group %d", i);
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unlock_super (VFSTOEXT2(mp)->um_devvp);
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return 0;
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}
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search_back:
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/*
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* We have succeeded in finding a free byte in the block
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* bitmap. Now search backwards up to 7 bits to find the
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* start of this group of free blocks.
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*/
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for (k = 0; k < 7 && j > 0 && !test_bit (j - 1, bh->b_data); k++, j--);
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got_block:
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ext2_debug ("using block group %d(%d)\n", i, gdp->bg_free_blocks_count);
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tmp = j + i * EXT2_BLOCKS_PER_GROUP(sb) + es->s_first_data_block;
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if (/* test_opt (sb, CHECK_STRICT) && we are always strict. */
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(tmp == gdp->bg_block_bitmap ||
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tmp == gdp->bg_inode_bitmap ||
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in_range (tmp, gdp->bg_inode_table, sb->s_itb_per_group)))
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panic ( "ext2_new_block: "
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"Allocating block in system zone - "
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"%dth block = %u in group %u", j, tmp, i);
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if (set_bit (j, bh->b_data)) {
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printf ( "ext2_new_block: "
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"bit already set for block %d", j);
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goto repeat;
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}
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ext2_debug ("found bit %d\n", j);
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/*
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* Do block preallocation now if required.
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*/
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#ifdef EXT2_PREALLOCATE
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if (prealloc_block) {
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*prealloc_count = 0;
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*prealloc_block = tmp + 1;
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for (k = 1;
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k < 8 && (j + k) < EXT2_BLOCKS_PER_GROUP(sb); k++) {
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if (set_bit (j + k, bh->b_data))
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break;
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(*prealloc_count)++;
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}
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gdp->bg_free_blocks_count -= *prealloc_count;
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es->s_free_blocks_count -= *prealloc_count;
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ext2_debug ("Preallocated a further %lu bits.\n",
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*prealloc_count);
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}
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#endif
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j = tmp;
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mark_buffer_dirty(bh);
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/****
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if (sb->s_flags & MS_SYNCHRONOUS) {
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ll_rw_block (WRITE, 1, &bh);
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wait_on_buffer (bh);
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}
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****/
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if (j >= es->s_blocks_count) {
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printf ( "ext2_new_block: "
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"block >= blocks count - "
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"block_group = %d, block=%d", i, j);
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unlock_super (VFSTOEXT2(mp)->um_devvp);
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return 0;
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}
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ext2_debug ("allocating block %d. "
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"Goal hits %d of %d.\n", j, goal_hits, goal_attempts);
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gdp->bg_free_blocks_count--;
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mark_buffer_dirty(bh2);
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es->s_free_blocks_count--;
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sb->s_dirt = 1;
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unlock_super (VFSTOEXT2(mp)->um_devvp);
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return j;
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}
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#ifdef unused
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static unsigned long ext2_count_free_blocks (struct mount * mp)
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{
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struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
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#ifdef EXT2FS_DEBUG
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struct ext2_super_block * es;
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unsigned long desc_count, bitmap_count, x;
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int bitmap_nr;
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struct ext2_group_desc * gdp;
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int i;
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lock_super (VFSTOEXT2(mp)->um_devvp);
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es = sb->s_es;
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desc_count = 0;
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bitmap_count = 0;
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gdp = NULL;
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for (i = 0; i < sb->s_groups_count; i++) {
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gdp = get_group_desc (mp, i, NULL);
|
|
desc_count += gdp->bg_free_blocks_count;
|
|
bitmap_nr = load_block_bitmap (mp, i);
|
|
x = ext2_count_free (sb->s_block_bitmap[bitmap_nr],
|
|
sb->s_blocksize);
|
|
ext2_debug ("group %d: stored = %d, counted = %lu\n",
|
|
i, gdp->bg_free_blocks_count, x);
|
|
bitmap_count += x;
|
|
}
|
|
ext2_debug( "stored = %lu, computed = %lu, %lu\n",
|
|
es->s_free_blocks_count, desc_count, bitmap_count);
|
|
unlock_super (VFSTOEXT2(mp)->um_devvp);
|
|
return bitmap_count;
|
|
#else
|
|
return sb->s_es->s_free_blocks_count;
|
|
#endif
|
|
}
|
|
#endif /* unused */
|
|
|
|
static __inline int block_in_use (unsigned long block,
|
|
struct ext2_sb_info * sb,
|
|
unsigned char * map)
|
|
{
|
|
return test_bit ((block - sb->s_es->s_first_data_block) %
|
|
EXT2_BLOCKS_PER_GROUP(sb), map);
|
|
}
|
|
|
|
static int test_root(int a, int b)
|
|
{
|
|
if (a == 0)
|
|
return 1;
|
|
while (1) {
|
|
if (a == 1)
|
|
return 1;
|
|
if (a % b)
|
|
return 0;
|
|
a = a / b;
|
|
}
|
|
}
|
|
|
|
int ext2_group_sparse(int group)
|
|
{
|
|
return (test_root(group, 3) || test_root(group, 5) ||
|
|
test_root(group, 7));
|
|
}
|
|
|
|
#ifdef unused
|
|
static void ext2_check_blocks_bitmap (struct mount * mp)
|
|
{
|
|
struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
|
|
struct buffer_head * bh;
|
|
struct ext2_super_block * es;
|
|
unsigned long desc_count, bitmap_count, x;
|
|
unsigned long desc_blocks;
|
|
int bitmap_nr;
|
|
struct ext2_group_desc * gdp;
|
|
int i, j;
|
|
|
|
lock_super (VFSTOEXT2(mp)->um_devvp);
|
|
es = sb->s_es;
|
|
desc_count = 0;
|
|
bitmap_count = 0;
|
|
gdp = NULL;
|
|
desc_blocks = (sb->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
|
|
EXT2_DESC_PER_BLOCK(sb);
|
|
for (i = 0; i < sb->s_groups_count; i++) {
|
|
gdp = get_group_desc (mp, i, NULL);
|
|
desc_count += gdp->bg_free_blocks_count;
|
|
bitmap_nr = load_block_bitmap (mp, i);
|
|
bh = sb->s_block_bitmap[bitmap_nr];
|
|
|
|
if (!(es->s_feature_ro_compat &
|
|
EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER) ||
|
|
ext2_group_sparse(i)) {
|
|
if (!test_bit (0, bh->b_data))
|
|
printf ("ext2_check_blocks_bitmap: "
|
|
"Superblock in group %d "
|
|
"is marked free", i);
|
|
|
|
for (j = 0; j < desc_blocks; j++)
|
|
if (!test_bit (j + 1, bh->b_data))
|
|
printf ("ext2_check_blocks_bitmap: "
|
|
"Descriptor block #%d in group "
|
|
"%d is marked free", j, i);
|
|
}
|
|
|
|
if (!block_in_use (gdp->bg_block_bitmap, sb, bh->b_data))
|
|
printf ("ext2_check_blocks_bitmap: "
|
|
"Block bitmap for group %d is marked free",
|
|
i);
|
|
|
|
if (!block_in_use (gdp->bg_inode_bitmap, sb, bh->b_data))
|
|
printf ("ext2_check_blocks_bitmap: "
|
|
"Inode bitmap for group %d is marked free",
|
|
i);
|
|
|
|
for (j = 0; j < sb->s_itb_per_group; j++)
|
|
if (!block_in_use (gdp->bg_inode_table + j, sb, bh->b_data))
|
|
printf ("ext2_check_blocks_bitmap: "
|
|
"Block #%d of the inode table in "
|
|
"group %d is marked free", j, i);
|
|
|
|
x = ext2_count_free (bh, sb->s_blocksize);
|
|
if (gdp->bg_free_blocks_count != x)
|
|
printf ("ext2_check_blocks_bitmap: "
|
|
"Wrong free blocks count for group %d, "
|
|
"stored = %d, counted = %lu", i,
|
|
gdp->bg_free_blocks_count, x);
|
|
bitmap_count += x;
|
|
}
|
|
if (es->s_free_blocks_count != bitmap_count)
|
|
printf ("ext2_check_blocks_bitmap: "
|
|
"Wrong free blocks count in super block, "
|
|
"stored = %lu, counted = %lu",
|
|
(unsigned long) es->s_free_blocks_count, bitmap_count);
|
|
unlock_super (VFSTOEXT2(mp)->um_devvp);
|
|
}
|
|
#endif /* unused */
|
|
|
|
/*
|
|
* this function is taken from
|
|
* linux/fs/ext2/bitmap.c
|
|
*/
|
|
|
|
static int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
|
|
|
|
unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
|
|
{
|
|
unsigned int i;
|
|
unsigned long sum = 0;
|
|
|
|
if (!map)
|
|
return (0);
|
|
for (i = 0; i < numchars; i++)
|
|
sum += nibblemap[map->b_data[i] & 0xf] +
|
|
nibblemap[(map->b_data[i] >> 4) & 0xf];
|
|
return (sum);
|
|
}
|