Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> writes:
> There are several reasons to add a general function ext4_mb_mark_context
> to update block bitmap and group descriptor on disk:
> 1. pair behavior of alloc/free bits. For example,
> ext4_mb_new_blocks_simple will update free_clusters in struct flex_groups
> in ext4_mb_mark_bb while ext4_free_blocks_simple forgets this.
> 2. remove repeat code to read from disk, update and write back to disk.
> 3. reduce future unit test mocks to catch real IO to update structure
> on disk.
>
> Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
> ---
> fs/ext4/mballoc.c | 147 ++++++++++++++++++++++++----------------------
> 1 file changed, 77 insertions(+), 70 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index cf09adfbaf11..e1320eea46e9 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -3953,6 +3953,80 @@ void ext4_exit_mballoc(void)
> ext4_groupinfo_destroy_slabs();
> }
>
> +static int
> +ext4_mb_mark_context(struct super_block *sb, bool state, ext4_group_t group,
> + ext4_grpblk_t blkoff, ext4_grpblk_t len)
ext4_grpblk_t is defined as int.
/* data type for block offset of block group */
typedef int ext4_grpblk_t;
I think len should be unsigned int (u32) here.
> +{
> + struct ext4_sb_info *sbi = EXT4_SB(sb);
> + struct buffer_head *bitmap_bh = NULL;
> + struct ext4_group_desc *gdp;
> + struct buffer_head *gdp_bh;
> + int err;
> + unsigned int i, already, changed;
> +
> + bitmap_bh = ext4_read_block_bitmap(sb, group);
> + if (IS_ERR(bitmap_bh))
> + return PTR_ERR(bitmap_bh);
> +
> + err = -EIO;
> + gdp = ext4_get_group_desc(sb, group, &gdp_bh);
> + if (!gdp)
> + goto out_err;
> +
> + ext4_lock_group(sb, group);
> + if (ext4_has_group_desc_csum(sb) &&
> + (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
> + gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
> + ext4_free_group_clusters_set(sb, gdp,
> + ext4_free_clusters_after_init(sb, group, gdp));
> + }
> +
> + already = 0;
> + for (i = 0; i < len; i++)
> + if (mb_test_bit(blkoff + i, bitmap_bh->b_data) ==
> + state)
> + already++;
> + changed = len - already;
> +
> + if (state) {
> + mb_set_bits(bitmap_bh->b_data, blkoff, len);
> + ext4_free_group_clusters_set(sb, gdp,
> + ext4_free_group_clusters(sb, gdp) - changed);
> + } else {
> + mb_clear_bits(bitmap_bh->b_data, blkoff, len);
> + ext4_free_group_clusters_set(sb, gdp,
> + ext4_free_group_clusters(sb, gdp) + changed);
> + }
> +
> + ext4_block_bitmap_csum_set(sb, gdp, bitmap_bh);
> + ext4_group_desc_csum_set(sb, group, gdp);
> + ext4_unlock_group(sb, group);
> +
> + if (sbi->s_log_groups_per_flex) {
> + ext4_group_t flex_group = ext4_flex_group(sbi, group);
> + struct flex_groups *fg = sbi_array_rcu_deref(sbi,
> + s_flex_groups, flex_group);
> +
> + if (state)
> + atomic64_sub(changed, &fg->free_clusters);
> + else
> + atomic64_add(changed, &fg->free_clusters);
> + }
> +
> + err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh);
> + if (err)
> + goto out_err;
> + err = ext4_handle_dirty_metadata(NULL, NULL, gdp_bh);
> + if (err)
> + goto out_err;
> +
> + sync_dirty_buffer(bitmap_bh);
> + sync_dirty_buffer(gdp_bh);
> +
> +out_err:
> + brelse(bitmap_bh);
> + return err;
> +}
>
> /*
> * Check quota and mark chosen space (ac->ac_b_ex) non-free in bitmaps
> @@ -4079,15 +4153,11 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
> void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
> int len, bool state)
Even ext4_mb_mark_bb should take len as unsigned int IMO.
For e.g. ext4_fc_replay_add_range() passes map.m_len which is also
unsigned int.
Otherwise the patch looks good to me. Feel free to add -
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
-ritesh
