/* * linux/fs/ext4/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@redhat.com), 1993 * Big-endian to little-endian byte-swapping/bitmaps by * David S. Miller (davem@caip.rutgers.edu), 1995 */ #include <linux/time.h> #include <linux/capability.h> #include <linux/fs.h> #include <linux/jbd2.h> #include <linux/quotaops.h> #include <linux/buffer_head.h> #include "ext4.h" #include "ext4_jbd2.h" #include "mballoc.h" /* * balloc.c contains the blocks allocation and deallocation routines */ /* * Calculate the block group number and offset, given a block number */ void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr, ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp) { struct ext4_super_block *es = EXT4_SB(sb)->s_es; ext4_grpblk_t offset; blocknr = blocknr - le32_to_cpu(es->s_first_data_block); offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)); if (offsetp) *offsetp = offset; if (blockgrpp) *blockgrpp = blocknr; } static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block, ext4_group_t block_group) { ext4_group_t actual_group; ext4_get_group_no_and_offset(sb, block, &actual_group, NULL); if (actual_group == block_group) return 1; return 0; } static int ext4_group_used_meta_blocks(struct super_block *sb, ext4_group_t block_group, struct ext4_group_desc *gdp) { ext4_fsblk_t tmp; struct ext4_sb_info *sbi = EXT4_SB(sb); /* block bitmap, inode bitmap, and inode table blocks */ int used_blocks = sbi->s_itb_per_group + 2; if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) { if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) used_blocks--; if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) used_blocks--; tmp = ext4_inode_table(sb, gdp); for (; tmp < ext4_inode_table(sb, gdp) + sbi->s_itb_per_group; tmp++) { if (!ext4_block_in_group(sb, tmp, block_group)) used_blocks -= 1; } } return used_blocks; } /* Initializes an uninitialized block bitmap if given, and returns the * number of blocks free in the group. */ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, ext4_group_t block_group, struct ext4_group_desc *gdp) { int bit, bit_max; ext4_group_t ngroups = ext4_get_groups_count(sb); unsigned free_blocks, group_blocks; struct ext4_sb_info *sbi = EXT4_SB(sb); if (bh) { J_ASSERT_BH(bh, buffer_locked(bh)); /* If checksum is bad mark all blocks used to prevent allocation * essentially implementing a per-group read-only flag. */ if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) { ext4_error(sb, "Checksum bad for group %u", block_group); ext4_free_blks_set(sb, gdp, 0); ext4_free_inodes_set(sb, gdp, 0); ext4_itable_unused_set(sb, gdp, 0); memset(bh->b_data, 0xff, sb->s_blocksize); return 0; } memset(bh->b_data, 0, sb->s_blocksize); } /* Check for superblock and gdt backups in this group */ bit_max = ext4_bg_has_super(sb, block_group); if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) || block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) * sbi->s_desc_per_block) { if (bit_max) { bit_max += ext4_bg_num_gdb(sb, block_group); bit_max += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks); } } else { /* For META_BG_BLOCK_GROUPS */ bit_max += ext4_bg_num_gdb(sb, block_group); } if (block_group == ngroups - 1) { /* * Even though mke2fs always initialize first and last group * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need * to make sure we calculate the right free blocks */ group_blocks = ext4_blocks_count(sbi->s_es) - ext4_group_first_block_no(sb, ngroups - 1); } else { group_blocks = EXT4_BLOCKS_PER_GROUP(sb); } free_blocks = group_blocks - bit_max; if (bh) { ext4_fsblk_t start, tmp; int flex_bg = 0; for (bit = 0; bit < bit_max; bit++) ext4_set_bit(bit, bh->b_data); start = ext4_group_first_block_no(sb, block_group); if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) flex_bg = 1; /* Set bits for block and inode bitmaps, and inode table */ tmp = ext4_block_bitmap(sb, gdp); if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(tmp - start, bh->b_data); tmp = ext4_inode_bitmap(sb, gdp); if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(tmp - start, bh->b_data); tmp = ext4_inode_table(sb, gdp); for (; tmp < ext4_inode_table(sb, gdp) + sbi->s_itb_per_group; tmp++) { if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(tmp - start, bh->b_data); } /* * Also if the number of blocks within the group is * less than the blocksize * 8 ( which is the size * of bitmap ), set rest of the block bitmap to 1 */ mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data); } return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp); } /* * 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 ext4_fill_super). */ /** * ext4_get_group_desc() -- load group descriptor from disk * @sb: super block * @block_group: given block group * @bh: pointer to the buffer head to store the block * group descriptor */ struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb, ext4_group_t block_group, struct buffer_head **bh) { unsigned int group_desc; unsigned int offset; ext4_group_t ngroups = ext4_get_groups_count(sb); struct ext4_group_desc *desc; struct ext4_sb_info *sbi = EXT4_SB(sb); if (block_group >= ngroups) { ext4_error(sb, "block_group >= groups_count - block_group = %u," " groups_count = %u", block_group, ngroups); return NULL; } group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb); offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1); if (!sbi->s_group_desc[group_desc]) { ext4_error(sb, "Group descriptor not loaded - " "block_group = %u, group_desc = %u, desc = %u", block_group, group_desc, offset); return NULL; } desc = (struct ext4_group_desc *)( (__u8 *)sbi->s_group_desc[group_desc]->b_data + offset * EXT4_DESC_SIZE(sb)); if (bh) *bh = sbi->s_group_desc[group_desc]; return desc; } static int ext4_valid_block_bitmap(struct super_block *sb, struct ext4_group_desc *desc, unsigned int block_group, struct buffer_head *bh) { ext4_grpblk_t offset; ext4_grpblk_t next_zero_bit; ext4_fsblk_t bitmap_blk; ext4_fsblk_t group_first_block; if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) { /* with FLEX_BG, the inode/block bitmaps and itable * blocks may not be in the group at all * so the bitmap validation will be skipped for those groups * or it has to also read the block group where the bitmaps * are located to verify they are set. */ return 1; } group_first_block = ext4_group_first_block_no(sb, block_group); /* check whether block bitmap block number is set */ bitmap_blk = ext4_block_bitmap(sb, desc); offset = bitmap_blk - group_first_block; if (!ext4_test_bit(offset, bh->b_data)) /* bad block bitmap */ goto err_out; /* check whether the inode bitmap block number is set */ bitmap_blk = ext4_inode_bitmap(sb, desc); offset = bitmap_blk - group_first_block; if (!ext4_test_bit(offset, bh->b_data)) /* bad block bitmap */ goto err_out; /* check whether the inode table block number is set */ bitmap_blk = ext4_inode_table(sb, desc); offset = bitmap_blk - group_first_block; next_zero_bit = ext4_find_next_zero_bit(bh->b_data, offset + EXT4_SB(sb)->s_itb_per_group, offset); if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group) /* good bitmap for inode tables */ return 1; err_out: ext4_error(sb, "Invalid block bitmap - block_group = %d, block = %llu", block_group, bitmap_blk); return 0; } /** * ext4_read_block_bitmap() * @sb: super block * @block_group: given block group * * Read the bitmap for a given block_group,and validate the * bits for block/inode/inode tables are set in the bitmaps * * Return buffer_head on success or NULL in case of failure. */ struct buffer_head * ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group) { struct ext4_group_desc *desc; struct buffer_head *bh = NULL; ext4_fsblk_t bitmap_blk; desc = ext4_get_group_desc(sb, block_group, NULL); if (!desc) return NULL; bitmap_blk = ext4_block_bitmap(sb, desc); bh = sb_getblk(sb, bitmap_blk); if (unlikely(!bh)) { ext4_error(sb, "Cannot read block bitmap - " "block_group = %u, block_bitmap = %llu", block_group, bitmap_blk); return NULL; } if (bitmap_uptodate(bh)) return bh; lock_buffer(bh); if (bitmap_uptodate(bh)) { unlock_buffer(bh); return bh; } ext4_lock_group(sb, block_group); if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { ext4_init_block_bitmap(sb, bh, block_group, desc); set_bitmap_uptodate(bh); set_buffer_uptodate(bh); ext4_unlock_group(sb, block_group); unlock_buffer(bh); return bh; } ext4_unlock_group(sb, block_group); if (buffer_uptodate(bh)) { /* * if not uninit if bh is uptodate, * bitmap is also uptodate */ set_bitmap_uptodate(bh); unlock_buffer(bh); return bh; } /* * submit the buffer_head for read. We can * safely mark the bitmap as uptodate now. * We do it here so the bitmap uptodate bit * get set with buffer lock held. */ set_bitmap_uptodate(bh); if (bh_submit_read(bh) < 0) { put_bh(bh); ext4_error(sb, "Cannot read block bitmap - " "block_group = %u, block_bitmap = %llu", block_group, bitmap_blk); return NULL; } ext4_valid_block_bitmap(sb, desc, block_group, bh); /* * file system mounted not to panic on error, * continue with corrupt bitmap */ return bh; } /** * ext4_add_groupblocks() -- Add given blocks to an existing group * @handle: handle to this transaction * @sb: super block * @block: start physcial block to add to the block group * @count: number of blocks to free * * This marks the blocks as free in the bitmap. We ask the * mballoc to reload the buddy after this by setting group * EXT4_GROUP_INFO_NEED_INIT_BIT flag */ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb, ext4_fsblk_t block, unsigned long count) { struct buffer_head *bitmap_bh = NULL; struct buffer_head *gd_bh; ext4_group_t block_group; ext4_grpblk_t bit; unsigned int i; struct ext4_group_desc *desc; struct ext4_sb_info *sbi = EXT4_SB(sb); int err = 0, ret, blk_free_count; ext4_grpblk_t blocks_freed; struct ext4_group_info *grp; ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1); ext4_get_group_no_and_offset(sb, block, &block_group, &bit); grp = ext4_get_group_info(sb, block_group); /* * Check to see if we are freeing blocks across a group * boundary. */ if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) { goto error_return; } bitmap_bh = ext4_read_block_bitmap(sb, block_group); if (!bitmap_bh) goto error_return; desc = ext4_get_group_desc(sb, block_group, &gd_bh); if (!desc) goto error_return; if (in_range(ext4_block_bitmap(sb, desc), block, count) || in_range(ext4_inode_bitmap(sb, desc), block, count) || in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) || in_range(block + count - 1, ext4_inode_table(sb, desc), sbi->s_itb_per_group)) { ext4_error(sb, "Adding blocks in system zones - " "Block = %llu, count = %lu", block, count); goto error_return; } /* * We are about to add blocks to the bitmap, * so we need undo access. */ BUFFER_TRACE(bitmap_bh, "getting undo access"); err = ext4_journal_get_undo_access(handle, bitmap_bh); if (err) goto error_return; /* * We are about to modify some metadata. Call the journal APIs * to unshare ->b_data if a currently-committing transaction is * using it */ BUFFER_TRACE(gd_bh, "get_write_access"); err = ext4_journal_get_write_access(handle, gd_bh); if (err) goto error_return; /* * make sure we don't allow a parallel init on other groups in the * same buddy cache */ down_write(&grp->alloc_sem); for (i = 0, blocks_freed = 0; i < count; i++) { BUFFER_TRACE(bitmap_bh, "clear bit"); if (!ext4_clear_bit_atomic(ext4_group_lock_ptr(sb, block_group), bit + i, bitmap_bh->b_data)) { ext4_error(sb, "bit already cleared for block %llu", (ext4_fsblk_t)(block + i)); BUFFER_TRACE(bitmap_bh, "bit already cleared"); } else { blocks_freed++; } } ext4_lock_group(sb, block_group); blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc); ext4_free_blks_set(sb, desc, blk_free_count); desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc); ext4_unlock_group(sb, block_group); percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed); if (sbi->s_log_groups_per_flex) { ext4_group_t flex_group = ext4_flex_group(sbi, block_group); atomic_add(blocks_freed, &sbi->s_flex_groups[flex_group].free_blocks); } /* * request to reload the buddy with the * new bitmap information */ set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state)); grp->bb_free += blocks_freed; up_write(&grp->alloc_sem); /* We dirtied the bitmap block */ BUFFER_TRACE(bitmap_bh, "dirtied bitmap block"); err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh); /* And the group descriptor block */ BUFFER_TRACE(gd_bh, "dirtied group descriptor block"); ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh); if (!err) err = ret; error_return: brelse(bitmap_bh); ext4_std_error(sb, err); return; } /** * ext4_has_free_blocks() * @sbi: in-core super block structure. * @nblocks: number of needed blocks * * Check if filesystem has nblocks free & available for allocation. * On success return 1, return 0 on failure. */ int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks) { s64 free_blocks, dirty_blocks, root_blocks; struct percpu_counter *fbc = &sbi->s_freeblocks_counter; struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter; free_blocks = percpu_counter_read_positive(fbc); dirty_blocks = percpu_counter_read_positive(dbc); root_blocks = ext4_r_blocks_count(sbi->s_es); if (free_blocks - (nblocks + root_blocks + dirty_blocks) < EXT4_FREEBLOCKS_WATERMARK) { free_blocks = percpu_counter_sum_positive(fbc); dirty_blocks = percpu_counter_sum_positive(dbc); if (dirty_blocks < 0) { printk(KERN_CRIT "Dirty block accounting " "went wrong %lld\n", (long long)dirty_blocks); } } /* Check whether we have space after * accounting for current dirty blocks & root reserved blocks. */ if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks)) return 1; /* Hm, nope. Are (enough) root reserved blocks available? */ if (sbi->s_resuid == current_fsuid() || ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) || capable(CAP_SYS_RESOURCE)) { if (free_blocks >= (nblocks + dirty_blocks)) return 1; } return 0; } int ext4_claim_free_blocks(struct ext4_sb_info *sbi, s64 nblocks) { if (ext4_has_free_blocks(sbi, nblocks)) { percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks); return 0; } else return -ENOSPC; } /** * ext4_should_retry_alloc() * @sb: super block * @retries number of attemps has been made * * ext4_should_retry_alloc() is called when ENOSPC is returned, and if * it is profitable to retry the operation, this function will wait * for the current or commiting transaction to complete, and then * return TRUE. * * if the total number of retries exceed three times, return FALSE. */ int ext4_should_retry_alloc(struct super_block *sb, int *retries) { if (!ext4_has_free_blocks(EXT4_SB(sb), 1) || (*retries)++ > 3 || !EXT4_SB(sb)->s_journal) return 0; jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id); return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal); } /* * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks * * @handle: handle to this transaction * @inode: file inode * @goal: given target block(filesystem wide) * @count: pointer to total number of blocks needed * @errp: error code * * Return 1st allocated block number on success, *count stores total account * error stores in errp pointer */ ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode, ext4_fsblk_t goal, unsigned long *count, int *errp) { struct ext4_allocation_request ar; ext4_fsblk_t ret; memset(&ar, 0, sizeof(ar)); /* Fill with neighbour allocated blocks */ ar.inode = inode; ar.goal = goal; ar.len = count ? *count : 1; ret = ext4_mb_new_blocks(handle, &ar, errp); if (count) *count = ar.len; /* * Account for the allocated meta blocks. We will never * fail EDQUOT for metdata, but we do account for it. */ if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) { spin_lock(&EXT4_I(inode)->i_block_reservation_lock); EXT4_I(inode)->i_allocated_meta_blocks += ar.len; spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); dquot_alloc_block_nofail(inode, ar.len); } return ret; } /** * ext4_count_free_blocks() -- count filesystem free blocks * @sb: superblock * * Adds up the number of free blocks from each block group. */ ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb) { ext4_fsblk_t desc_count; struct ext4_group_desc *gdp; ext4_group_t i; ext4_group_t ngroups = ext4_get_groups_count(sb); #ifdef EXT4FS_DEBUG struct ext4_super_block *es; ext4_fsblk_t bitmap_count; unsigned int x; struct buffer_head *bitmap_bh = NULL; es = EXT4_SB(sb)->s_es; desc_count = 0; bitmap_count = 0; gdp = NULL; for (i = 0; i < ngroups; i++) { gdp = ext4_get_group_desc(sb, i, NULL); if (!gdp) continue; desc_count += ext4_free_blks_count(sb, gdp); brelse(bitmap_bh); bitmap_bh = ext4_read_block_bitmap(sb, i); if (bitmap_bh == NULL) continue; x = ext4_count_free(bitmap_bh, sb->s_blocksize); printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n", i, ext4_free_blks_count(sb, gdp), x); bitmap_count += x; } brelse(bitmap_bh); printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu" ", computed = %llu, %llu\n", ext4_free_blocks_count(es), desc_count, bitmap_count); return bitmap_count; #else desc_count = 0; for (i = 0; i < ngroups; i++) { gdp = ext4_get_group_desc(sb, i, NULL); if (!gdp) continue; desc_count += ext4_free_blks_count(sb, gdp); } return desc_count; #endif } static inline int test_root(ext4_group_t a, int b) { int num = b; while (a > num) num *= b; return num == a; } static int ext4_group_sparse(ext4_group_t group) { if (group <= 1) return 1; if (!(group & 1)) return 0; return (test_root(group, 7) || test_root(group, 5) || test_root(group, 3)); } /** * ext4_bg_has_super - number of blocks used by the superblock in group * @sb: superblock for filesystem * @group: group number to check * * Return the number of blocks used by the superblock (primary or backup) * in this group. Currently this will be only 0 or 1. */ int ext4_bg_has_super(struct super_block *sb, ext4_group_t group) { if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) && !ext4_group_sparse(group)) return 0; return 1; } static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, ext4_group_t group) { unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb); ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1; if (group == first || group == first + 1 || group == last) return 1; return 0; } static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, ext4_group_t group) { if (!ext4_bg_has_super(sb, group)) return 0; if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG)) return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); else return EXT4_SB(sb)->s_gdb_count; } /** * ext4_bg_num_gdb - number of blocks used by the group table in group * @sb: superblock for filesystem * @group: group number to check * * Return the number of blocks used by the group descriptor table * (primary or backup) in this group. In the future there may be a * different number of descriptor blocks in each group. */ unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group) { unsigned long first_meta_bg = le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) || metagroup < first_meta_bg) return ext4_bg_num_gdb_nometa(sb, group); return ext4_bg_num_gdb_meta(sb,group); }