/* $OpenBSD: ext2_linux_balloc.c,v 1.3 1996/10/18 15:23:36 mickey Exp $ */ /* * modified for Lites 1.1 * * Aug 1995, Godmar Back (gback@cs.utah.edu) * University of Utah, Department of Computer Science */ /* * linux/fs/ext2/balloc.c * * Copyright (C) 1992, 1993, 1994, 1995 * Remy Card (card@masi.ibp.fr) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) * * Enhanced block allocation by Stephen Tweedie (sct@dcs.ed.ac.uk), 1993 */ /* * The free blocks are managed by bitmaps. A file system contains several * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap * block for inodes, N blocks for the inode table and data blocks. * * The file system contains group descriptors which are located after the * super block. Each descriptor contains the number of the bitmap block and * the free blocks count in the block. The descriptors are loaded in memory * when a file system is mounted (see ext2_read_super). */ #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(__GNUC__) #define INLINE __inline__ #endif #include #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1) /* got rid of get_group_desc since it can already be found in * ext2_linux_ialloc.c */ static void read_block_bitmap (struct mount * mp, unsigned int block_group, unsigned long bitmap_nr) { struct ext2_sb_info *sb = VFSTOUFS(mp)->um_e2fs; struct ext2_group_desc * gdp; struct buffer_head * bh; int error; gdp = get_group_desc (mp, block_group, NULL); error = bread (VFSTOUFS(mp)->um_devvp, fsbtodb(sb, gdp->bg_block_bitmap),sb->s_blocksize, NOCRED, &bh); if (error != 0) panic ( "read_block_bitmap: " "Cannot read block bitmap - " "block_group = %d, block_bitmap = %lu", block_group, (unsigned long) gdp->bg_block_bitmap); sb->s_block_bitmap_number[bitmap_nr] = block_group; sb->s_block_bitmap[bitmap_nr] = bh; } /* * load_block_bitmap loads the block bitmap for a blocks group * * It maintains a cache for the last bitmaps loaded. This cache is managed * with a LRU algorithm. * * Notes: * 1/ There is one cache per mounted file system. * 2/ If the file system contains less than EXT2_MAX_GROUP_LOADED groups, * this function reads the bitmap without maintaining a LRU cache. */ static int load__block_bitmap (struct mount * mp, unsigned int block_group) { int i, j; struct ext2_sb_info *sb = VFSTOUFS(mp)->um_e2fs; unsigned long block_bitmap_number; struct buffer_head * block_bitmap; if (block_group >= sb->s_groups_count) panic ( "load_block_bitmap: " "block_group >= groups_count - " "block_group = %d, groups_count = %lu", block_group, sb->s_groups_count); if (sb->s_groups_count <= EXT2_MAX_GROUP_LOADED) { if (sb->s_block_bitmap[block_group]) { if (sb->s_block_bitmap_number[block_group] != block_group) panic ( "load_block_bitmap: " "block_group != block_bitmap_number"); else return block_group; } else { read_block_bitmap (mp, block_group, block_group); return block_group; } } for (i = 0; i < sb->s_loaded_block_bitmaps && sb->s_block_bitmap_number[i] != block_group; i++) ; if (i < sb->s_loaded_block_bitmaps && sb->s_block_bitmap_number[i] == block_group) { block_bitmap_number = sb->s_block_bitmap_number[i]; block_bitmap = sb->s_block_bitmap[i]; for (j = i; j > 0; j--) { sb->s_block_bitmap_number[j] = sb->s_block_bitmap_number[j - 1]; sb->s_block_bitmap[j] = sb->s_block_bitmap[j - 1]; } sb->s_block_bitmap_number[0] = block_bitmap_number; sb->s_block_bitmap[0] = block_bitmap; } else { if (sb->s_loaded_block_bitmaps < EXT2_MAX_GROUP_LOADED) sb->s_loaded_block_bitmaps++; else brelse (sb->s_block_bitmap[EXT2_MAX_GROUP_LOADED - 1]); for (j = sb->s_loaded_block_bitmaps - 1; j > 0; j--) { sb->s_block_bitmap_number[j] = sb->s_block_bitmap_number[j - 1]; sb->s_block_bitmap[j] = sb->s_block_bitmap[j - 1]; } read_block_bitmap (mp, block_group, 0); } return 0; } static INLINE int load_block_bitmap (struct mount * mp, unsigned int block_group) { struct ext2_sb_info *sb = VFSTOUFS(mp)->um_e2fs; if (sb->s_loaded_block_bitmaps > 0 && sb->s_block_bitmap_number[0] == block_group) return 0; if (sb->s_groups_count <= EXT2_MAX_GROUP_LOADED && sb->s_block_bitmap_number[block_group] == block_group && sb->s_block_bitmap[block_group]) return block_group; return load__block_bitmap (mp, block_group); } void ext2_free_blocks (struct mount * mp, unsigned long block, unsigned long count) { struct ext2_sb_info *sb = VFSTOUFS(mp)->um_e2fs; struct buffer_head * bh; struct buffer_head * bh2; unsigned long block_group; unsigned long bit; unsigned long i; int bitmap_nr; struct ext2_group_desc * gdp; struct ext2_super_block * es = sb->s_es; if (!sb) { printf ("ext2_free_blocks: nonexistent device"); return; } lock_super (VFSTOUFS(mp)->um_devvp); if (block < es->s_first_data_block || (block + count) > es->s_blocks_count) { printf ( "ext2_free_blocks: " "Freeing blocks not in datazone - " "block = %lu, count = %lu", block, count); unlock_super (VFSTOUFS(mp)->um_devvp); return; } ext2_debug ("freeing blocks %lu to %lu\n", block, block+count-1); block_group = (block - es->s_first_data_block) / EXT2_BLOCKS_PER_GROUP(sb); bit = (block - es->s_first_data_block) % EXT2_BLOCKS_PER_GROUP(sb); if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) panic ( "ext2_free_blocks: " "Freeing blocks across group boundary - " "Block = %lu, count = %lu", block, count); bitmap_nr = load_block_bitmap (mp, block_group); bh = sb->s_block_bitmap[bitmap_nr]; gdp = get_group_desc (mp, block_group, &bh2); if (/* test_opt (sb, CHECK_STRICT) && assume always strict ! */ (in_range (gdp->bg_block_bitmap, block, count) || in_range (gdp->bg_inode_bitmap, block, count) || in_range (block, gdp->bg_inode_table, sb->s_itb_per_group) || in_range (block + count - 1, gdp->bg_inode_table, sb->s_itb_per_group))) panic ( "ext2_free_blocks: " "Freeing blocks in system zones - " "Block = %lu, count = %lu", block, count); for (i = 0; i < count; i++) { if (!ext2fs_clear_bit (bit + i, bh->b_data)) printf ("ext2_free_blocks: " "bit already cleared for block %lu", block); else { gdp->bg_free_blocks_count++; es->s_free_blocks_count++; } } mark_buffer_dirty(bh2); mark_buffer_dirty(bh); /**** if (sb->s_flags & MS_SYNCHRONOUS) { ll_rw_block (WRITE, 1, &bh); wait_on_buffer (bh); } ****/ sb->s_dirt = 1; unlock_super (VFSTOUFS(mp)->um_devvp); return; } /* * ext2_new_block uses a goal block to assist allocation. If the goal is * free, or there is a free block within 32 blocks of the goal, that block * is allocated. Otherwise a forward search is made for a free block; within * each block group the search first looks for an entire free byte in the block * bitmap, and then for any free bit if that fails. */ int ext2_new_block (struct mount * mp, u_int32_t goal, int32_t * prealloc_count, int32_t * prealloc_block) { struct ext2_sb_info *sb = VFSTOUFS(mp)->um_e2fs; struct buffer_head * bh; struct buffer_head * bh2; char * p, * r; int i, j, k, tmp; int bitmap_nr; struct ext2_group_desc * gdp; struct ext2_super_block * es = sb->s_es; #ifdef EXT2FS_DEBUG static int goal_hits = 0, goal_attempts = 0; #endif if (!sb) { printf ("ext2_new_block: nonexistent device"); return 0; } lock_super (VFSTOUFS(mp)->um_devvp); ext2_debug ("goal=%lu.\n", goal); repeat: /* * First, test whether the goal block is free. */ if (goal < es->s_first_data_block || goal >= es->s_blocks_count) goal = es->s_first_data_block; i = (goal - es->s_first_data_block) / EXT2_BLOCKS_PER_GROUP(sb); gdp = get_group_desc (mp, i, &bh2); if (gdp->bg_free_blocks_count > 0) { j = ((goal - es->s_first_data_block) % EXT2_BLOCKS_PER_GROUP(sb)); #ifdef EXT2FS_DEBUG if (j) goal_attempts++; #endif bitmap_nr = load_block_bitmap (mp, i); bh = sb->s_block_bitmap[bitmap_nr]; ext2_debug ("goal is at %d:%d.\n", i, j); if (!ext2fs_test_bit(j, bh->b_data)) { #ifdef EXT2FS_DEBUG goal_hits++; ext2_debug ("goal bit allocated.\n"); #endif goto got_block; } if (j) { /* * The goal was occupied; search forward for a free * block within the next XX blocks. * * end_goal is more or less random, but it has to be * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the * next 64-bit boundary is simple.. */ int end_goal = (j + 63) & ~63; j = ext2fs_fnzb(bh->b_data, end_goal, j); if (j < end_goal) goto got_block; } ext2_debug ("Bit not found near goal\n"); /* * There has been no free block found in the near vicinity * of the goal: do a search forward through the block groups, * searching in each group first for an entire free byte in * the bitmap and then for any free bit. * * Search first in the remainder of the current group; then, * cyclicly search through the rest of the groups. */ p = ((char *) bh->b_data) + (j >> 3); r = ext2fs_memscan(p, 0, (EXT2_BLOCKS_PER_GROUP(sb) - j + 7) >> 3); k = (r - ((char *) bh->b_data)) << 3; if (k < EXT2_BLOCKS_PER_GROUP(sb)) { j = k; goto search_back; } k = ext2fs_fnzb ((unsigned long *) bh->b_data, EXT2_BLOCKS_PER_GROUP(sb), j); if (k < EXT2_BLOCKS_PER_GROUP(sb)) { j = k; goto got_block; } } ext2_debug ("Bit not found in block group %d.\n", i); /* * Now search the rest of the groups. We assume that * i and gdp correctly point to the last group visited. */ for (k = 0; k < sb->s_groups_count; k++) { i++; if (i >= sb->s_groups_count) i = 0; gdp = get_group_desc (mp, i, &bh2); if (gdp->bg_free_blocks_count > 0) break; } if (k >= sb->s_groups_count) { unlock_super (VFSTOUFS(mp)->um_devvp); return 0; } bitmap_nr = load_block_bitmap (mp, i); bh = sb->s_block_bitmap[bitmap_nr]; r = ext2fs_memscan(bh->b_data, 0, EXT2_BLOCKS_PER_GROUP(sb) >> 3); j = (r - bh->b_data) << 3; if (j < EXT2_BLOCKS_PER_GROUP(sb)) goto search_back; else j = ext2fs_ffzb ((unsigned long *) bh->b_data, EXT2_BLOCKS_PER_GROUP(sb)); if (j >= EXT2_BLOCKS_PER_GROUP(sb)) { printf ( "ext2_new_block: " "Free blocks count corrupted for block group %d", i); unlock_super (VFSTOUFS(mp)->um_devvp); return 0; } search_back: /* * We have succeeded in finding a free byte in the block * bitmap. Now search backwards up to 7 bits to find the * start of this group of free blocks. */ for (k = 0; k < 7 && j > 0 && !ext2fs_test_bit (j - 1, bh->b_data); k++, j--); got_block: ext2_debug ("using block group %d(%d)\n", i, gdp->bg_free_blocks_count); tmp = j + i * EXT2_BLOCKS_PER_GROUP(sb) + es->s_first_data_block; if (/* test_opt (sb, CHECK_STRICT) && we are always strict. */ (tmp == gdp->bg_block_bitmap || tmp == gdp->bg_inode_bitmap || in_range (tmp, gdp->bg_inode_table, sb->s_itb_per_group))) panic ( "ext2_new_block: " "Allocating block in system zone - " "%dth block = %u in group %u", j, tmp, i); if (ext2fs_set_bit (j, bh->b_data)) { printf ( "ext2_new_block: " "bit already set for block %d", j); goto repeat; } ext2_debug ("found bit %d\n", j); /* * Do block preallocation now if required. */ #ifdef EXT2_PREALLOCATE if (prealloc_block) { *prealloc_count = 0; *prealloc_block = tmp + 1; for (k = 1; k < 8 && (j + k) < EXT2_BLOCKS_PER_GROUP(sb); k++) { if (ext2fs_set_bit (j + k, bh->b_data)) break; (*prealloc_count)++; } gdp->bg_free_blocks_count -= *prealloc_count; es->s_free_blocks_count -= *prealloc_count; ext2_debug ("Preallocated a further %lu bits.\n", *prealloc_count); } #endif j = tmp; mark_buffer_dirty(bh); /**** if (sb->s_flags & MS_SYNCHRONOUS) { ll_rw_block (WRITE, 1, &bh); wait_on_buffer (bh); } ****/ if (j >= es->s_blocks_count) { printf ( "ext2_new_block: " "block >= blocks count - " "block_group = %d, block=%d", i, j); unlock_super (VFSTOUFS(mp)->um_devvp); return 0; } ext2_debug ("allocating block %d. " "Goal hits %d of %d.\n", j, goal_hits, goal_attempts); gdp->bg_free_blocks_count--; mark_buffer_dirty(bh2); es->s_free_blocks_count--; sb->s_dirt = 1; unlock_super (VFSTOUFS(mp)->um_devvp); return j; } #if 0 static unsigned long ext2_count_free_blocks (struct mount * mp) { struct ext2_sb_info *sb = VFSTOUFS(mp)->um_e2fs; #ifdef EXT2FS_DEBUG struct ext2_super_block * es; unsigned long desc_count, bitmap_count, x; int bitmap_nr; struct ext2_group_desc * gdp; int i; lock_super (VFSTOUFS(mp)->um_devvp); es = sb->s_es; desc_count = 0; bitmap_count = 0; gdp = NULL; 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); 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 (VFSTOUFS(mp)->um_devvp); return bitmap_count; #else return sb->s_es->s_free_blocks_count; #endif } #endif static INLINE int block_in_use (unsigned long block, struct ext2_sb_info * sb, unsigned char * map) { return ext2fs_test_bit ((block - sb->s_es->s_first_data_block) % EXT2_BLOCKS_PER_GROUP(sb), map); } #if 0 static void ext2_check_blocks_bitmap (struct mount * mp) { struct ext2_sb_info *sb = VFSTOUFS(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 (VFSTOUFS(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 (!ext2fs_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 (!ext2fs_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 (VFSTOUFS(mp)->um_devvp); } #endif /* * 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); }