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-rw-r--r--fs/ext4/balloc.c992
1 files changed, 992 insertions, 0 deletions
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
new file mode 100644
index 000000000..fbd0329cf
--- /dev/null
+++ b/fs/ext4/balloc.c
@@ -0,0 +1,992 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/quotaops.h>
+#include <linux/buffer_head.h>
+#include "ext4.h"
+#include "ext4_jbd2.h"
+#include "mballoc.h"
+
+#include <trace/events/ext4.h>
+
+static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
+ ext4_group_t block_group);
+/*
+ * balloc.c contains the blocks allocation and deallocation routines
+ */
+
+/*
+ * Calculate block group number for a given block number
+ */
+ext4_group_t ext4_get_group_number(struct super_block *sb,
+ ext4_fsblk_t block)
+{
+ ext4_group_t group;
+
+ if (test_opt2(sb, STD_GROUP_SIZE))
+ group = (block -
+ le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
+ (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
+ else
+ ext4_get_group_no_and_offset(sb, block, &group, NULL);
+ return group;
+}
+
+/*
+ * 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;
+
+}
+
+/*
+ * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
+ * and 0 otherwise.
+ */
+static inline int ext4_block_in_group(struct super_block *sb,
+ ext4_fsblk_t block,
+ ext4_group_t block_group)
+{
+ ext4_group_t actual_group;
+
+ actual_group = ext4_get_group_number(sb, block);
+ return (actual_group == block_group) ? 1 : 0;
+}
+
+/* Return the number of clusters used for file system metadata; this
+ * represents the overhead needed by the file system.
+ */
+static 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,
+ ext4_block_bitmap(sb, gdp) - start);
+ 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,
+ ext4_inode_bitmap(sb, gdp) - start);
+ 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, itbl_blk + i - start);
+ 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 */
+static int 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;
+
+ ASSERT(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(sb, block_group, gdp)) {
+ ext4_mark_group_bitmap_corrupted(sb, block_group,
+ EXT4_GROUP_INFO_BBITMAP_CORRUPT |
+ EXT4_GROUP_INFO_IBITMAP_CORRUPT);
+ return -EFSBADCRC;
+ }
+ memset(bh->b_data, 0, sb->s_blocksize);
+
+ bit_max = ext4_num_base_meta_clusters(sb, block_group);
+ if ((bit_max >> 3) >= bh->b_size)
+ return -EFSCORRUPTED;
+
+ for (bit = 0; bit < bit_max; bit++)
+ ext4_set_bit(bit, bh->b_data);
+
+ start = ext4_group_first_block_no(sb, block_group);
+
+ /* Set bits for block and inode bitmaps, and inode table */
+ tmp = ext4_block_bitmap(sb, gdp);
+ if (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 (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 (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 0;
+}
+
+/* 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);
+ struct buffer_head *bh_p;
+
+ 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);
+ bh_p = sbi_array_rcu_deref(sbi, s_group_desc, group_desc);
+ /*
+ * sbi_array_rcu_deref returns with rcu unlocked, this is ok since
+ * the pointer being dereferenced won't be dereferenced again. By
+ * looking at the usage in add_new_gdb() the value isn't modified,
+ * just the pointer, and so it remains valid.
+ */
+ if (!bh_p) {
+ 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 *)bh_p->b_data +
+ offset * EXT4_DESC_SIZE(sb));
+ if (bh)
+ *bh = bh_p;
+ return desc;
+}
+
+static ext4_fsblk_t ext4_valid_block_bitmap_padding(struct super_block *sb,
+ ext4_group_t block_group,
+ struct buffer_head *bh)
+{
+ ext4_grpblk_t next_zero_bit;
+ unsigned long bitmap_size = sb->s_blocksize * 8;
+ unsigned int offset = num_clusters_in_group(sb, block_group);
+
+ if (bitmap_size <= offset)
+ return 0;
+
+ next_zero_bit = ext4_find_next_zero_bit(bh->b_data, bitmap_size, offset);
+
+ return (next_zero_bit < bitmap_size ? next_zero_bit : 0);
+}
+
+struct ext4_group_info *ext4_get_group_info(struct super_block *sb,
+ ext4_group_t group)
+{
+ struct ext4_group_info **grp_info;
+ long indexv, indexh;
+
+ if (unlikely(group >= EXT4_SB(sb)->s_groups_count))
+ return NULL;
+ indexv = group >> (EXT4_DESC_PER_BLOCK_BITS(sb));
+ indexh = group & ((EXT4_DESC_PER_BLOCK(sb)) - 1);
+ grp_info = sbi_array_rcu_deref(EXT4_SB(sb), s_group_info, indexv);
+ return grp_info[indexh];
+}
+
+/*
+ * Return the block number which was discovered to be invalid, or 0 if
+ * the block bitmap is valid.
+ */
+static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
+ struct ext4_group_desc *desc,
+ ext4_group_t block_group,
+ struct buffer_head *bh)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ ext4_grpblk_t offset;
+ ext4_grpblk_t next_zero_bit;
+ ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
+ ext4_fsblk_t blk;
+ ext4_fsblk_t group_first_block;
+
+ if (ext4_has_feature_flex_bg(sb)) {
+ /* 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 0;
+ }
+ group_first_block = ext4_group_first_block_no(sb, block_group);
+
+ /* check whether block bitmap block number is set */
+ blk = ext4_block_bitmap(sb, desc);
+ offset = blk - group_first_block;
+ if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
+ !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
+ /* bad block bitmap */
+ return blk;
+
+ /* check whether the inode bitmap block number is set */
+ blk = ext4_inode_bitmap(sb, desc);
+ offset = blk - group_first_block;
+ if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
+ !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
+ /* bad block bitmap */
+ return blk;
+
+ /* check whether the inode table block number is set */
+ blk = ext4_inode_table(sb, desc);
+ offset = blk - group_first_block;
+ if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
+ EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit)
+ return blk;
+ next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
+ EXT4_B2C(sbi, offset + sbi->s_itb_per_group),
+ EXT4_B2C(sbi, offset));
+ if (next_zero_bit <
+ EXT4_B2C(sbi, offset + sbi->s_itb_per_group))
+ /* bad bitmap for inode tables */
+ return blk;
+ return 0;
+}
+
+static int ext4_validate_block_bitmap(struct super_block *sb,
+ struct ext4_group_desc *desc,
+ ext4_group_t block_group,
+ struct buffer_head *bh)
+{
+ ext4_fsblk_t blk;
+ struct ext4_group_info *grp;
+
+ if (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY)
+ return 0;
+
+ grp = ext4_get_group_info(sb, block_group);
+
+ if (buffer_verified(bh))
+ return 0;
+ if (!grp || EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
+ return -EFSCORRUPTED;
+
+ ext4_lock_group(sb, block_group);
+ if (buffer_verified(bh))
+ goto verified;
+ if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
+ desc, bh) ||
+ ext4_simulate_fail(sb, EXT4_SIM_BBITMAP_CRC))) {
+ ext4_unlock_group(sb, block_group);
+ ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
+ ext4_mark_group_bitmap_corrupted(sb, block_group,
+ EXT4_GROUP_INFO_BBITMAP_CORRUPT);
+ return -EFSBADCRC;
+ }
+ blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
+ if (unlikely(blk != 0)) {
+ ext4_unlock_group(sb, block_group);
+ ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
+ block_group, blk);
+ ext4_mark_group_bitmap_corrupted(sb, block_group,
+ EXT4_GROUP_INFO_BBITMAP_CORRUPT);
+ return -EFSCORRUPTED;
+ }
+ blk = ext4_valid_block_bitmap_padding(sb, block_group, bh);
+ if (unlikely(blk != 0)) {
+ ext4_unlock_group(sb, block_group);
+ ext4_error(sb, "bg %u: block %llu: padding at end of block bitmap is not set",
+ block_group, blk);
+ ext4_mark_group_bitmap_corrupted(sb, block_group,
+ EXT4_GROUP_INFO_BBITMAP_CORRUPT);
+ return -EFSCORRUPTED;
+ }
+ set_buffer_verified(bh);
+verified:
+ ext4_unlock_group(sb, block_group);
+ return 0;
+}
+
+/**
+ * ext4_read_block_bitmap_nowait()
+ * @sb: super block
+ * @block_group: given block group
+ * @ignore_locked: ignore locked buffers
+ *
+ * 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 an ERR_PTR in case of failure.
+ */
+struct buffer_head *
+ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group,
+ bool ignore_locked)
+{
+ struct ext4_group_desc *desc;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ struct buffer_head *bh;
+ ext4_fsblk_t bitmap_blk;
+ int err;
+
+ desc = ext4_get_group_desc(sb, block_group, NULL);
+ if (!desc)
+ return ERR_PTR(-EFSCORRUPTED);
+ bitmap_blk = ext4_block_bitmap(sb, desc);
+ if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
+ (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
+ ext4_error(sb, "Invalid block bitmap block %llu in "
+ "block_group %u", bitmap_blk, block_group);
+ ext4_mark_group_bitmap_corrupted(sb, block_group,
+ EXT4_GROUP_INFO_BBITMAP_CORRUPT);
+ return ERR_PTR(-EFSCORRUPTED);
+ }
+ bh = sb_getblk(sb, bitmap_blk);
+ if (unlikely(!bh)) {
+ ext4_warning(sb, "Cannot get buffer for block bitmap - "
+ "block_group = %u, block_bitmap = %llu",
+ block_group, bitmap_blk);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ if (ignore_locked && buffer_locked(bh)) {
+ /* buffer under IO already, return if called for prefetching */
+ put_bh(bh);
+ return NULL;
+ }
+
+ if (bitmap_uptodate(bh))
+ goto verify;
+
+ lock_buffer(bh);
+ if (bitmap_uptodate(bh)) {
+ unlock_buffer(bh);
+ goto verify;
+ }
+ ext4_lock_group(sb, block_group);
+ if (ext4_has_group_desc_csum(sb) &&
+ (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
+ if (block_group == 0) {
+ ext4_unlock_group(sb, block_group);
+ unlock_buffer(bh);
+ ext4_error(sb, "Block bitmap for bg 0 marked "
+ "uninitialized");
+ err = -EFSCORRUPTED;
+ goto out;
+ }
+ err = ext4_init_block_bitmap(sb, bh, block_group, desc);
+ set_bitmap_uptodate(bh);
+ set_buffer_uptodate(bh);
+ set_buffer_verified(bh);
+ ext4_unlock_group(sb, block_group);
+ unlock_buffer(bh);
+ if (err) {
+ ext4_error(sb, "Failed to init block bitmap for group "
+ "%u: %d", block_group, err);
+ goto out;
+ }
+ goto verify;
+ }
+ 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);
+ goto verify;
+ }
+ /*
+ * submit the buffer_head for reading
+ */
+ set_buffer_new(bh);
+ trace_ext4_read_block_bitmap_load(sb, block_group, ignore_locked);
+ ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO |
+ (ignore_locked ? REQ_RAHEAD : 0),
+ ext4_end_bitmap_read);
+ return bh;
+verify:
+ err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
+ if (err)
+ goto out;
+ return bh;
+out:
+ put_bh(bh);
+ return ERR_PTR(err);
+}
+
+/* Returns 0 on success, -errno on error */
+int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
+ struct buffer_head *bh)
+{
+ struct ext4_group_desc *desc;
+
+ if (!buffer_new(bh))
+ return 0;
+ desc = ext4_get_group_desc(sb, block_group, NULL);
+ if (!desc)
+ return -EFSCORRUPTED;
+ wait_on_buffer(bh);
+ ext4_simulate_fail_bh(sb, bh, EXT4_SIM_BBITMAP_EIO);
+ if (!buffer_uptodate(bh)) {
+ ext4_error_err(sb, EIO, "Cannot read block bitmap - "
+ "block_group = %u, block_bitmap = %llu",
+ block_group, (unsigned long long) bh->b_blocknr);
+ ext4_mark_group_bitmap_corrupted(sb, block_group,
+ EXT4_GROUP_INFO_BBITMAP_CORRUPT);
+ return -EIO;
+ }
+ clear_buffer_new(bh);
+ /* Panic or remount fs read-only if block bitmap is invalid */
+ return ext4_validate_block_bitmap(sb, desc, block_group, bh);
+}
+
+struct buffer_head *
+ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
+{
+ struct buffer_head *bh;
+ int err;
+
+ bh = ext4_read_block_bitmap_nowait(sb, block_group, false);
+ if (IS_ERR(bh))
+ return bh;
+ err = ext4_wait_block_bitmap(sb, block_group, bh);
+ if (err) {
+ put_bh(bh);
+ return ERR_PTR(err);
+ }
+ return bh;
+}
+
+/**
+ * ext4_has_free_clusters()
+ * @sbi: in-core super block structure.
+ * @nclusters: number of needed blocks
+ * @flags: flags from ext4_mb_new_blocks()
+ *
+ * Check if filesystem has nclusters free & available for allocation.
+ * On success return 1, return 0 on failure.
+ */
+static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
+ s64 nclusters, unsigned int flags)
+{
+ s64 free_clusters, dirty_clusters, rsv, resv_clusters;
+ struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
+ struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
+
+ free_clusters = percpu_counter_read_positive(fcc);
+ dirty_clusters = percpu_counter_read_positive(dcc);
+ resv_clusters = atomic64_read(&sbi->s_resv_clusters);
+
+ /*
+ * r_blocks_count should always be multiple of the cluster ratio so
+ * we are safe to do a plane bit shift only.
+ */
+ rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
+ resv_clusters;
+
+ if (free_clusters - (nclusters + rsv + dirty_clusters) <
+ EXT4_FREECLUSTERS_WATERMARK) {
+ free_clusters = percpu_counter_sum_positive(fcc);
+ dirty_clusters = percpu_counter_sum_positive(dcc);
+ }
+ /* Check whether we have space after accounting for current
+ * dirty clusters & root reserved clusters.
+ */
+ if (free_clusters >= (rsv + nclusters + dirty_clusters))
+ return 1;
+
+ /* Hm, nope. Are (enough) root reserved clusters available? */
+ if (uid_eq(sbi->s_resuid, current_fsuid()) ||
+ (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
+ capable(CAP_SYS_RESOURCE) ||
+ (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
+
+ if (free_clusters >= (nclusters + dirty_clusters +
+ resv_clusters))
+ return 1;
+ }
+ /* No free blocks. Let's see if we can dip into reserved pool */
+ if (flags & EXT4_MB_USE_RESERVED) {
+ if (free_clusters >= (nclusters + dirty_clusters))
+ return 1;
+ }
+
+ return 0;
+}
+
+int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
+ s64 nclusters, unsigned int flags)
+{
+ if (ext4_has_free_clusters(sbi, nclusters, flags)) {
+ percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
+ return 0;
+ } else
+ return -ENOSPC;
+}
+
+/**
+ * ext4_should_retry_alloc() - check if a block allocation should be retried
+ * @sb: superblock
+ * @retries: number of retry attempts made so far
+ *
+ * ext4_should_retry_alloc() is called when ENOSPC is returned while
+ * attempting to allocate blocks. If there's an indication that a pending
+ * journal transaction might free some space and allow another attempt to
+ * succeed, this function will wait for the current or committing transaction
+ * to complete and then return TRUE.
+ */
+int ext4_should_retry_alloc(struct super_block *sb, int *retries)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ if (!sbi->s_journal)
+ return 0;
+
+ if (++(*retries) > 3) {
+ percpu_counter_inc(&sbi->s_sra_exceeded_retry_limit);
+ return 0;
+ }
+
+ /*
+ * if there's no indication that blocks are about to be freed it's
+ * possible we just missed a transaction commit that did so
+ */
+ smp_mb();
+ if (sbi->s_mb_free_pending == 0) {
+ if (test_opt(sb, DISCARD)) {
+ atomic_inc(&sbi->s_retry_alloc_pending);
+ flush_work(&sbi->s_discard_work);
+ atomic_dec(&sbi->s_retry_alloc_pending);
+ }
+ return ext4_has_free_clusters(sbi, 1, 0);
+ }
+
+ /*
+ * it's possible we've just missed a transaction commit here,
+ * so ignore the returned status
+ */
+ ext4_debug("%s: retrying operation after ENOSPC\n", sb->s_id);
+ (void) jbd2_journal_force_commit_nested(sbi->s_journal);
+ return 1;
+}
+
+/*
+ * 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) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
+ 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);
+ struct ext4_group_info *grp;
+#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;
+ grp = NULL;
+ if (EXT4_SB(sb)->s_group_info)
+ grp = ext4_get_group_info(sb, i);
+ if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
+ desc_count += ext4_free_group_clusters(sb, gdp);
+ brelse(bitmap_bh);
+ bitmap_bh = ext4_read_block_bitmap(sb, i);
+ if (IS_ERR(bitmap_bh)) {
+ bitmap_bh = NULL;
+ continue;
+ }
+
+ x = ext4_count_free(bitmap_bh->b_data,
+ EXT4_CLUSTERS_PER_GROUP(sb) / 8);
+ 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_NUM_B2C(EXT4_SB(sb), 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;
+ grp = NULL;
+ if (EXT4_SB(sb)->s_group_info)
+ grp = ext4_get_group_info(sb, i);
+ if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
+ desc_count += ext4_free_group_clusters(sb, gdp);
+ }
+
+ return desc_count;
+#endif
+}
+
+static inline int test_root(ext4_group_t a, int b)
+{
+ while (1) {
+ if (a < b)
+ return 0;
+ if (a == b)
+ return 1;
+ if ((a % b) != 0)
+ return 0;
+ a = a / b;
+ }
+}
+
+/**
+ * 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)
+{
+ struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+
+ if (group == 0)
+ return 1;
+ if (ext4_has_feature_sparse_super2(sb)) {
+ if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
+ group == le32_to_cpu(es->s_backup_bgs[1]))
+ return 1;
+ return 0;
+ }
+ if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
+ return 1;
+ if (!(group & 1))
+ return 0;
+ if (test_root(group, 3) || (test_root(group, 5)) ||
+ test_root(group, 7))
+ return 1;
+
+ return 0;
+}
+
+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_feature_meta_bg(sb))
+ 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_feature_meta_bg(sb) || 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 blocks at
+ * the beginning of a block group, including the reserved gdt blocks.
+ */
+unsigned int ext4_num_base_meta_blocks(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_feature_meta_bg(sb) ||
+ 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 num;
+}
+
+static unsigned int ext4_num_base_meta_clusters(struct super_block *sb,
+ ext4_group_t block_group)
+{
+ return EXT4_NUM_B2C(EXT4_SB(sb), ext4_num_base_meta_blocks(sb, block_group));
+}
+
+/**
+ * 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 = (task_pid_nr(current) % 16) *
+ (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
+ else
+ colour = (task_pid_nr(current) % 16) *
+ ((last_block - bg_start) / 16);
+ return bg_start + colour;
+}
+