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Message-ID: <ZGCr74q8dfqMgq0t@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com>
Date: Sun, 14 May 2023 15:07:51 +0530
From: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
To: Kemeng Shi <shikemeng@...weicloud.com>
Cc: tytso@....edu, adilger.kernel@...ger.ca,
linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 15/19] ext4: call ext4_mb_mark_group_bb in
ext4_mb_mark_diskspace_used
On Mon, Apr 17, 2023 at 07:06:13PM +0800, Kemeng Shi wrote:
> call ext4_mb_mark_group_bb in ext4_mb_mark_diskspace_used to:
> 1. remove repeat code to normally update bitmap and group descriptor
> on disk.
> 2. call ext4_mb_mark_group_bb instead of only setting bits in block bitmap
> to fix the bitmap. Function ext4_mb_mark_group_bb will also update
> checksum of bitmap and other counter along with the bit change to keep
> the cosistent with bit change or block bitmap will be marked corrupted as
> checksum of bitmap is in inconsistent state.
>
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
Looks good, feel free to add:
Reviewed-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
Just a minor suggestion below:
> ---
> fs/ext4/mballoc.c | 90 +++++++++++++----------------------------------
> 1 file changed, 24 insertions(+), 66 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index c3e620f6eded..bd440614db76 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -3846,9 +3846,12 @@ static noinline_for_stack int
> ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
> handle_t *handle, unsigned int reserv_clstrs)
> {
> - struct buffer_head *bitmap_bh = NULL;
> + struct ext4_mark_context mc = {
> + .handle = handle,
> + .sb = ac->ac_sb,
> + .state = 1,
> + };
> struct ext4_group_desc *gdp;
> - struct buffer_head *gdp_bh;
> struct ext4_sb_info *sbi;
> struct super_block *sb;
> ext4_fsblk_t block;
> @@ -3860,32 +3863,13 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
> sb = ac->ac_sb;
> sbi = EXT4_SB(sb);
>
> - bitmap_bh = ext4_read_block_bitmap(sb, ac->ac_b_ex.fe_group);
> - if (IS_ERR(bitmap_bh)) {
> - return PTR_ERR(bitmap_bh);
> - }
> -
> - BUFFER_TRACE(bitmap_bh, "getting write access");
> - err = ext4_journal_get_write_access(handle, sb, bitmap_bh,
> - EXT4_JTR_NONE);
> - if (err)
> - goto out_err;
> -
> - err = -EIO;
> - gdp = ext4_get_group_desc(sb, ac->ac_b_ex.fe_group, &gdp_bh);
> + gdp = ext4_get_group_desc(sb, ac->ac_b_ex.fe_group, NULL);
> if (!gdp)
> - goto out_err;
> -
> + return -EIO;
> ext4_debug("using block group %u(%d)\n", ac->ac_b_ex.fe_group,
> ext4_free_group_clusters(sb, gdp));
>
> - BUFFER_TRACE(gdp_bh, "get_write_access");
> - err = ext4_journal_get_write_access(handle, sb, gdp_bh, EXT4_JTR_NONE);
> - if (err)
> - goto out_err;
> -
> block = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
> -
> len = EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
> if (!ext4_inode_block_valid(ac->ac_inode, block, len)) {
> ext4_error(sb, "Allocating blocks %llu-%llu which overlap "
> @@ -3894,41 +3878,30 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
> * Fix the bitmap and return EFSCORRUPTED
> * We leak some of the blocks here.
> */
> - ext4_lock_group(sb, ac->ac_b_ex.fe_group);
> - mb_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,
> - ac->ac_b_ex.fe_len);
> - ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
> - err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
> + err = ext4_mb_mark_group_bb(&mc, ac->ac_b_ex.fe_group,
> + ac->ac_b_ex.fe_start,
> + ac->ac_b_ex.fe_len,
> + 0);
> if (!err)
> err = -EFSCORRUPTED;
> - goto out_err;
> + return err;
> }
>
> - ext4_lock_group(sb, ac->ac_b_ex.fe_group);
> #ifdef AGGRESSIVE_CHECK
> - {
> - int i;
> - for (i = 0; i < ac->ac_b_ex.fe_len; i++) {
> - BUG_ON(mb_test_bit(ac->ac_b_ex.fe_start + i,
> - bitmap_bh->b_data));
> - }
> - }
> + err = ext4_mb_mark_group_bb(&mc, ac->ac_b_ex.fe_group,
> + ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len,
> + EXT4_MB_BITMAP_MARKED_CHECK);
> +#else
> + err = ext4_mb_mark_group_bb(&mc, ac->ac_b_ex.fe_group,
> + ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len,
> + 0);
> #endif
I think, the refactoring the AGGRESSIVE_CHECK as follows makes the
intent more obvious and easier to read.
#ifdef AGGRESSIVE_CHECK
flags |= EXT4_MB_BITMAP_MARKED_CHECK;
#endif
err = ext4_mb_mark_group_bb(&mc, ac->ac_b_ex.fe_group,
ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len,
flags);
Regards,
ojaswin
> - mb_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,
> - ac->ac_b_ex.fe_len);
> - 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,
> - ac->ac_b_ex.fe_group, gdp));
> - }
> - len = ext4_free_group_clusters(sb, gdp) - ac->ac_b_ex.fe_len;
> - ext4_free_group_clusters_set(sb, gdp, len);
> - ext4_block_bitmap_csum_set(sb, gdp, bitmap_bh);
> - ext4_group_desc_csum_set(sb, ac->ac_b_ex.fe_group, gdp);
> + if (err && mc.changed == 0)
> + return err;
>
> - ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
> +#ifdef AGGRESSIVE_CHECK
> + BUG_ON(mc.changed != ac->ac_b_ex.fe_len);
> +#endif
> percpu_counter_sub(&sbi->s_freeclusters_counter, ac->ac_b_ex.fe_len);
> /*
> * Now reduce the dirty block count also. Should not go negative
> @@ -3938,21 +3911,6 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
> percpu_counter_sub(&sbi->s_dirtyclusters_counter,
> reserv_clstrs);
>
> - if (sbi->s_log_groups_per_flex) {
> - ext4_group_t flex_group = ext4_flex_group(sbi,
> - ac->ac_b_ex.fe_group);
> - atomic64_sub(ac->ac_b_ex.fe_len,
> - &sbi_array_rcu_deref(sbi, s_flex_groups,
> - flex_group)->free_clusters);
> - }
> -
> - err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
> - if (err)
> - goto out_err;
> - err = ext4_handle_dirty_metadata(handle, NULL, gdp_bh);
> -
> -out_err:
> - brelse(bitmap_bh);
> return err;
> }
>
> --
> 2.30.0
>
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