Lemur zaprasza
/* * 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 */ /* * balloc.c contains the blocks allocation and deallocation routines */ /* * 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 <linux/fs.h> #include <linux/ext2_fs.h> #include <linux/stat.h> #include <linux/sched.h> #include <linux/string.h> #include <linux/locks.h> #include <asm/bitops.h> #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1) static struct ext2_group_desc * get_group_desc (struct super_block * sb, unsigned int block_group, struct buffer_head ** bh) { unsigned long group_desc; unsigned long desc; struct ext2_group_desc * gdp; if (block_group >= sb->u.ext2_sb.s_groups_count) ext2_panic (sb, "get_group_desc", "block_group >= groups_count - " "block_group = %d, groups_count = %lu", block_group, sb->u.ext2_sb.s_groups_count); group_desc = block_group / EXT2_DESC_PER_BLOCK(sb); desc = block_group % EXT2_DESC_PER_BLOCK(sb); if (!sb->u.ext2_sb.s_group_desc[group_desc]) ext2_panic (sb, "get_group_desc", "Group descriptor not loaded - " "block_group = %d, group_desc = %lu, desc = %lu", block_group, group_desc, desc); gdp = (struct ext2_group_desc *) sb->u.ext2_sb.s_group_desc[group_desc]->b_data; if (bh) *bh = sb->u.ext2_sb.s_group_desc[group_desc]; return gdp + desc; } static void read_block_bitmap (struct super_block * sb, unsigned int block_group, unsigned long bitmap_nr) { struct ext2_group_desc * gdp; struct buffer_head * bh; gdp = get_group_desc (sb, block_group, NULL); bh = bread (sb->s_dev, gdp->bg_block_bitmap, sb->s_blocksize); if (!bh) ext2_panic (sb, "read_block_bitmap", "Cannot read block bitmap - " "block_group = %d, block_bitmap = %lu", block_group, (unsigned long) gdp->bg_block_bitmap); sb->u.ext2_sb.s_block_bitmap_number[bitmap_nr] = block_group; sb->u.ext2_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 super_block * sb, unsigned int block_group) { int i, j; unsigned long block_bitmap_number; struct buffer_head * block_bitmap; if (block_group >= sb->u.ext2_sb.s_groups_count) ext2_panic (sb, "load_block_bitmap", "block_group >= groups_count - " "block_group = %d, groups_count = %lu", block_group, sb->u.ext2_sb.s_groups_count); if (sb->u.ext2_sb.s_groups_count <= EXT2_MAX_GROUP_LOADED) { if (sb->u.ext2_sb.s_block_bitmap[block_group]) { if (sb->u.ext2_sb.s_block_bitmap_number[block_group] != block_group) ext2_panic (sb, "load_block_bitmap", "block_group != block_bitmap_number"); else return block_group; } else { read_block_bitmap (sb, block_group, block_group); return block_group; } } for (i = 0; i < sb->u.ext2_sb.s_loaded_block_bitmaps && sb->u.ext2_sb.s_block_bitmap_number[i] != block_group; i++) ; if (i < sb->u.ext2_sb.s_loaded_block_bitmaps && sb->u.ext2_sb.s_block_bitmap_number[i] == block_group) { block_bitmap_number = sb->u.ext2_sb.s_block_bitmap_number[i]; block_bitmap = sb->u.ext2_sb.s_block_bitmap[i]; for (j = i; j > 0; j--) { sb->u.ext2_sb.s_block_bitmap_number[j] = sb->u.ext2_sb.s_block_bitmap_number[j - 1]; sb->u.ext2_sb.s_block_bitmap[j] = sb->u.ext2_sb.s_block_bitmap[j - 1]; } sb->u.ext2_sb.s_block_bitmap_number[0] = block_bitmap_number; sb->u.ext2_sb.s_block_bitmap[0] = block_bitmap; } else { if (sb->u.ext2_sb.s_loaded_block_bitmaps < EXT2_MAX_GROUP_LOADED) sb->u.ext2_sb.s_loaded_block_bitmaps++; else brelse (sb->u.ext2_sb.s_block_bitmap[EXT2_MAX_GROUP_LOADED - 1]); for (j = sb->u.ext2_sb.s_loaded_block_bitmaps - 1; j > 0; j--) { sb->u.ext2_sb.s_block_bitmap_number[j] = sb->u.ext2_sb.s_block_bitmap_number[j - 1]; sb->u.ext2_sb.s_block_bitmap[j] = sb->u.ext2_sb.s_block_bitmap[j - 1]; } read_block_bitmap (sb, block_group, 0); } return 0; } static inline int load_block_bitmap (struct super_block * sb, unsigned int block_group) { if (sb->u.ext2_sb.s_loaded_block_bitmaps > 0 && sb->u.ext2_sb.s_block_bitmap_number[0] == block_group) return 0; if (sb->u.ext2_sb.s_groups_count <= EXT2_MAX_GROUP_LOADED && sb->u.ext2_sb.s_block_bitmap_number[block_group] == block_group && sb->u.ext2_sb.s_block_bitmap[block_group]) return block_group; return load__block_bitmap (sb, block_group); } void ext2_free_blocks (const struct inode * inode, unsigned long block, unsigned long count) { struct buffer_head * bh; struct buffer_head * bh2; unsigned long block_group; unsigned long bit; unsigned long i; int bitmap_nr; struct super_block * sb; struct ext2_group_desc * gdp; struct ext2_super_block * es; sb = inode->i_sb; if (!sb) { printk ("ext2_free_blocks: nonexistent device"); return; } lock_super (sb); es = sb->u.ext2_sb.s_es; if (block < es->s_first_data_block || (block + count) > es->s_blocks_count) { ext2_error (sb, "ext2_free_blocks", "Freeing blocks not in datazone - " "block = %lu, count = %lu", block, count); unlock_super (sb); return; } ext2_debug ("freeing block %lu\n", block); 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)) ext2_panic (sb, "ext2_free_blocks", "Freeing blocks across group boundary - " "Block = %lu, count = %lu", block, count); bitmap_nr = load_block_bitmap (sb, block_group); bh = sb->u.ext2_sb.s_block_bitmap[bitmap_nr]; gdp = get_group_desc (sb, block_group, &bh2); if (test_opt (sb, CHECK_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->u.ext2_sb.s_itb_per_group) || in_range (block + count - 1, gdp->bg_inode_table, sb->u.ext2_sb.s_itb_per_group))) ext2_panic (sb, "ext2_free_blocks", "Freeing blocks in system zones - " "Block = %lu, count = %lu", block, count); for (i = 0; i < count; i++) { if (!clear_bit (bit + i, bh->b_data)) ext2_warning (sb, "ext2_free_blocks", "bit already cleared for block %lu", block); else { if (sb->dq_op) sb->dq_op->free_block(inode, fs_to_dq_blocks(1, sb->s_blocksize)); gdp->bg_free_blocks_count++; es->s_free_blocks_count++; } } mark_buffer_dirty(bh2, 1); mark_buffer_dirty(sb->u.ext2_sb.s_sbh, 1); mark_buffer_dirty(bh, 1); if (sb->s_flags & MS_SYNCHRONOUS) { ll_rw_block (WRITE, 1, &bh); wait_on_buffer (bh); } sb->s_dirt = 1; unlock_super (sb); 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 (const struct inode * inode, unsigned long goal, u32 * prealloc_count, u32 * prealloc_block, int * err) { struct buffer_head * bh; struct buffer_head * bh2; char * p, * r; int i, j, k, tmp; int bitmap_nr; struct super_block * sb; struct ext2_group_desc * gdp; struct ext2_super_block * es; *err = -ENOSPC; #ifdef EXT2FS_DEBUG static int goal_hits = 0, goal_attempts = 0; #endif sb = inode->i_sb; if (!sb) { printk ("ext2_new_block: nonexistent device"); return 0; } lock_super (sb); es = sb->u.ext2_sb.s_es; if (es->s_free_blocks_count <= es->s_r_blocks_count && (!fsuser() && (sb->u.ext2_sb.s_resuid != current->fsuid) && (sb->u.ext2_sb.s_resgid == 0 || !in_group_p (sb->u.ext2_sb.s_resgid)))) { unlock_super (sb); return 0; } 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 (sb, 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 (sb, i); bh = sb->u.ext2_sb.s_block_bitmap[bitmap_nr]; ext2_debug ("goal is at %d:%d.\n", i, j); if (!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 = find_next_zero_bit(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 = 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 = find_next_zero_bit ((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->u.ext2_sb.s_groups_count; k++) { i++; if (i >= sb->u.ext2_sb.s_groups_count) i = 0; gdp = get_group_desc (sb, i, &bh2); if (gdp->bg_free_blocks_count > 0) break; } if (k >= sb->u.ext2_sb.s_groups_count) { unlock_super (sb); return 0; } bitmap_nr = load_block_bitmap (sb, i); bh = sb->u.ext2_sb.s_block_bitmap[bitmap_nr]; r = 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 = find_first_zero_bit ((unsigned long *) bh->b_data, EXT2_BLOCKS_PER_GROUP(sb)); if (j >= EXT2_BLOCKS_PER_GROUP(sb)) { ext2_error (sb, "ext2_new_block", "Free blocks count corrupted for block group %d", i); unlock_super (sb); 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 && !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); /* * Check quota for allocation of this block. */ if (sb->dq_op) if (sb->dq_op->alloc_block (inode, fs_to_dq_blocks(1, sb->s_blocksize))) { unlock_super (sb); *err = -EDQUOT; return 0; } tmp = j + i * EXT2_BLOCKS_PER_GROUP(sb) + es->s_first_data_block; if (test_opt (sb, CHECK_STRICT) && (tmp == gdp->bg_block_bitmap || tmp == gdp->bg_inode_bitmap || in_range (tmp, gdp->bg_inode_table, sb->u.ext2_sb.s_itb_per_group))) ext2_panic (sb, "ext2_new_block", "Allocating block in system zone - " "block = %u", tmp); if (set_bit (j, bh->b_data)) { ext2_warning (sb, "ext2_new_block", "bit already set for block %d", j); if (sb->dq_op) sb->dq_op->free_block(inode, fs_to_dq_blocks(1, sb->s_blocksize)); 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 (sb->dq_op) if (sb->dq_op->alloc_block(inode, fs_to_dq_blocks(1, sb->s_blocksize))) break; if (set_bit (j + k, bh->b_data)) { if (sb->dq_op) sb->dq_op->free_block(inode, fs_to_dq_blocks(1, sb->s_blocksize)); 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, 1); if (sb->s_flags & MS_SYNCHRONOUS) { ll_rw_block (WRITE, 1, &bh); wait_on_buffer (bh); } if (j >= es->s_blocks_count) { ext2_error (sb, "ext2_new_block", "block >= blocks count - " "block_group = %d, block=%d", i, j); unlock_super (sb); return 0; } if (!(bh = getblk (sb->s_dev, j, sb->s_blocksize))) { ext2_error (sb, "ext2_new_block", "cannot get block %d", j); unlock_super (sb); return 0; } memset(bh->b_data, 0, sb->s_blocksize); mark_buffer_uptodate(bh, 1); mark_buffer_dirty(bh, 1); brelse (bh); 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, 1); es->s_free_blocks_count--; mark_buffer_dirty(sb->u.ext2_sb.s_sbh, 1); sb->s_dirt = 1; unlock_super (sb); *err = 0; return j; } unsigned long ext2_count_free_blocks (struct super_block * sb) { #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 (sb); es = sb->u.ext2_sb.s_es; desc_count = 0; bitmap_count = 0; gdp = NULL; for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++) { gdp = get_group_desc (sb, i, NULL); desc_count += gdp->bg_free_blocks_count; bitmap_nr = load_block_bitmap (sb, i); x = ext2_count_free (sb->u.ext2_sb.s_block_bitmap[bitmap_nr], sb->s_blocksize); printk ("group %d: stored = %d, counted = %lu\n", i, gdp->bg_free_blocks_count, x); bitmap_count += x; } printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n", es->s_free_blocks_count, desc_count, bitmap_count); unlock_super (sb); return bitmap_count; #else return sb->u.ext2_sb.s_es->s_free_blocks_count; #endif } static inline int block_in_use (unsigned long block, struct super_block * sb, unsigned char * map) { return test_bit ((block - sb->u.ext2_sb.s_es->s_first_data_block) % EXT2_BLOCKS_PER_GROUP(sb), map); } void ext2_check_blocks_bitmap (struct super_block * sb) { 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 (sb); es = sb->u.ext2_sb.s_es; desc_count = 0; bitmap_count = 0; gdp = NULL; desc_blocks = (sb->u.ext2_sb.s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) / EXT2_DESC_PER_BLOCK(sb); for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++) { gdp = get_group_desc (sb, i, NULL); desc_count += gdp->bg_free_blocks_count; bitmap_nr = load_block_bitmap (sb, i); bh = sb->u.ext2_sb.s_block_bitmap[bitmap_nr]; if (!test_bit (0, bh->b_data)) ext2_error (sb, "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)) ext2_error (sb, "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)) ext2_error (sb, "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)) ext2_error (sb, "ext2_check_blocks_bitmap", "Inode bitmap for group %d is marked free", i); for (j = 0; j < sb->u.ext2_sb.s_itb_per_group; j++) if (!block_in_use (gdp->bg_inode_table + j, sb, bh->b_data)) ext2_error (sb, "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) ext2_error (sb, "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) ext2_error (sb, "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 (sb); } |