| /* |
| * 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" |
| |
| #include <trace/events/ext4.h> |
| |
| /* |
| * balloc.c contains the blocks allocation and deallocation routines |
| */ |
| |
| /* |
| * Calculate the block group number and offset into the block/cluster |
| * allocation bitmap, 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)) >> |
| EXT4_SB(sb)->s_cluster_bits; |
| 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; |
| } |
| |
| /* Return the number of clusters used for file system metadata; this |
| * represents the overhead needed by the file system. |
| */ |
| unsigned ext4_num_overhead_clusters(struct super_block *sb, |
| ext4_group_t block_group, |
| struct ext4_group_desc *gdp) |
| { |
| unsigned num_clusters; |
| int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c; |
| ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group); |
| ext4_fsblk_t itbl_blk; |
| struct ext4_sb_info *sbi = EXT4_SB(sb); |
| |
| /* This is the number of clusters used by the superblock, |
| * block group descriptors, and reserved block group |
| * descriptor blocks */ |
| num_clusters = ext4_num_base_meta_clusters(sb, block_group); |
| |
| /* |
| * For the allocation bitmaps and inode table, we first need |
| * to check to see if the block is in the block group. If it |
| * is, then check to see if the cluster is already accounted |
| * for in the clusters used for the base metadata cluster, or |
| * if we can increment the base metadata cluster to include |
| * that block. Otherwise, we will have to track the cluster |
| * used for the allocation bitmap or inode table explicitly. |
| * Normally all of these blocks are contiguous, so the special |
| * case handling shouldn't be necessary except for *very* |
| * unusual file system layouts. |
| */ |
| if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) { |
| block_cluster = EXT4_B2C(sbi, (start - |
| ext4_block_bitmap(sb, gdp))); |
| if (block_cluster < num_clusters) |
| block_cluster = -1; |
| else if (block_cluster == num_clusters) { |
| num_clusters++; |
| block_cluster = -1; |
| } |
| } |
| |
| if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) { |
| inode_cluster = EXT4_B2C(sbi, |
| start - ext4_inode_bitmap(sb, gdp)); |
| if (inode_cluster < num_clusters) |
| inode_cluster = -1; |
| else if (inode_cluster == num_clusters) { |
| num_clusters++; |
| inode_cluster = -1; |
| } |
| } |
| |
| itbl_blk = ext4_inode_table(sb, gdp); |
| for (i = 0; i < sbi->s_itb_per_group; i++) { |
| if (ext4_block_in_group(sb, itbl_blk + i, block_group)) { |
| c = EXT4_B2C(sbi, start - itbl_blk + i); |
| if ((c < num_clusters) || (c == inode_cluster) || |
| (c == block_cluster) || (c == itbl_cluster)) |
| continue; |
| if (c == num_clusters) { |
| num_clusters++; |
| continue; |
| } |
| num_clusters++; |
| itbl_cluster = c; |
| } |
| } |
| |
| if (block_cluster != -1) |
| num_clusters++; |
| if (inode_cluster != -1) |
| num_clusters++; |
| |
| return num_clusters; |
| } |
| |
| static unsigned int num_clusters_in_group(struct super_block *sb, |
| ext4_group_t block_group) |
| { |
| unsigned int blocks; |
| |
| if (block_group == ext4_get_groups_count(sb) - 1) { |
| /* |
| * Even though mke2fs always initializes the first and |
| * last group, just in case some other tool was used, |
| * we need to make sure we calculate the right free |
| * blocks. |
| */ |
| blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) - |
| ext4_group_first_block_no(sb, block_group); |
| } else |
| blocks = EXT4_BLOCKS_PER_GROUP(sb); |
| return EXT4_NUM_B2C(EXT4_SB(sb), blocks); |
| } |
| |
| /* Initializes an uninitialized block bitmap */ |
| void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, |
| ext4_group_t block_group, |
| struct ext4_group_desc *gdp) |
| { |
| unsigned int bit, bit_max; |
| struct ext4_sb_info *sbi = EXT4_SB(sb); |
| ext4_fsblk_t start, tmp; |
| int flex_bg = 0; |
| |
| 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_group_clusters_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; |
| } |
| memset(bh->b_data, 0, sb->s_blocksize); |
| |
| bit_max = ext4_num_base_meta_clusters(sb, block_group); |
| 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(EXT4_B2C(sbi, 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(EXT4_B2C(sbi, 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(EXT4_B2C(sbi, 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 |
| */ |
| ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group), |
| sb->s_blocksize * 8, bh->b_data); |
| } |
| |
| /* Return the number of free blocks in a block group. It is used when |
| * the block bitmap is uninitialized, so we can't just count the bits |
| * in the bitmap. */ |
| unsigned ext4_free_clusters_after_init(struct super_block *sb, |
| ext4_group_t block_group, |
| struct ext4_group_desc *gdp) |
| { |
| return num_clusters_in_group(sb, block_group) - |
| ext4_num_overhead_clusters(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. |
| */ |
| trace_ext4_read_block_bitmap_load(sb, block_group); |
| 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_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. |
| */ |
| static int ext4_has_free_blocks(struct ext4_sb_info *sbi, |
| s64 nblocks, unsigned int flags) |
| { |
| s64 free_blocks, dirty_blocks, root_blocks; |
| struct percpu_counter *fcc = &sbi->s_freeclusters_counter; |
| struct percpu_counter *dbc = &sbi->s_dirtyclusters_counter; |
| |
| free_blocks = percpu_counter_read_positive(fcc); |
| 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 = EXT4_C2B(sbi, percpu_counter_sum_positive(fcc)); |
| dirty_blocks = percpu_counter_sum_positive(dbc); |
| } |
| /* 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) || |
| (flags & EXT4_MB_USE_ROOT_BLOCKS)) { |
| |
| if (free_blocks >= (nblocks + dirty_blocks)) |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| int ext4_claim_free_clusters(struct ext4_sb_info *sbi, |
| s64 nclusters, unsigned int flags) |
| { |
| if (ext4_has_free_blocks(sbi, nclusters, flags)) { |
| percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters); |
| 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 committing 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, 0) || |
| (*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 clusters 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 int flags, |
| 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; |
| ar.flags = flags; |
| |
| 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_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) { |
| 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, |
| EXT4_C2B(EXT4_SB(inode->i_sb), ar.len)); |
| } |
| return ret; |
| } |
| |
| /** |
| * ext4_count_free_clusters() -- count filesystem free clusters |
| * @sb: superblock |
| * |
| * Adds up the number of free clusters from each block group. |
| */ |
| ext4_fsblk_t ext4_count_free_clusters(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_group_clusters(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_group_clusters(sb, gdp), x); |
| bitmap_count += x; |
| } |
| brelse(bitmap_bh); |
| printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu" |
| ", computed = %llu, %llu\n", |
| EXT4_B2C(sbi, 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_group_clusters(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); |
| |
| } |
| |
| /* |
| * This function returns the number of file system metadata clusters at |
| * the beginning of a block group, including the reserved gdt blocks. |
| */ |
| unsigned ext4_num_base_meta_clusters(struct super_block *sb, |
| ext4_group_t block_group) |
| { |
| struct ext4_sb_info *sbi = EXT4_SB(sb); |
| unsigned num; |
| |
| /* Check for superblock and gdt backups in this group */ |
| num = 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 (num) { |
| num += ext4_bg_num_gdb(sb, block_group); |
| num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks); |
| } |
| } else { /* For META_BG_BLOCK_GROUPS */ |
| num += ext4_bg_num_gdb(sb, block_group); |
| } |
| return EXT4_NUM_B2C(sbi, num); |
| } |
| /** |
| * ext4_inode_to_goal_block - return a hint for block allocation |
| * @inode: inode for block allocation |
| * |
| * Return the ideal location to start allocating blocks for a |
| * newly created inode. |
| */ |
| ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode) |
| { |
| struct ext4_inode_info *ei = EXT4_I(inode); |
| ext4_group_t block_group; |
| ext4_grpblk_t colour; |
| int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb)); |
| ext4_fsblk_t bg_start; |
| ext4_fsblk_t last_block; |
| |
| block_group = ei->i_block_group; |
| if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) { |
| /* |
| * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME |
| * block groups per flexgroup, reserve the first block |
| * group for directories and special files. Regular |
| * files will start at the second block group. This |
| * tends to speed up directory access and improves |
| * fsck times. |
| */ |
| block_group &= ~(flex_size-1); |
| if (S_ISREG(inode->i_mode)) |
| block_group++; |
| } |
| bg_start = ext4_group_first_block_no(inode->i_sb, block_group); |
| last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1; |
| |
| /* |
| * If we are doing delayed allocation, we don't need take |
| * colour into account. |
| */ |
| if (test_opt(inode->i_sb, DELALLOC)) |
| return bg_start; |
| |
| if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block) |
| colour = (current->pid % 16) * |
| (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16); |
| else |
| colour = (current->pid % 16) * ((last_block - bg_start) / 16); |
| return bg_start + colour; |
| } |
| |