linux-ext4 - Re: [PATCH v3 3/4] ext4: make the updating inode data procedure atomic

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Date:   Mon, 23 Aug 2021 12:23:41 +0200
From:   Jan Kara <jack@...e.cz>
To:     Zhang Yi <yi.zhang@...wei.com>
Cc:     linux-ext4@...r.kernel.org, tytso@....edu,
        adilger.kernel@...ger.ca, jack@...e.cz, yukuai3@...wei.com
Subject: Re: [PATCH v3 3/4] ext4: make the updating inode data procedure
 atomic

On Sat 21-08-21 14:54:49, Zhang Yi wrote:
> Now that ext4_do_update_inode() return error before filling the whole
> inode data if we fail to set inode blocks in ext4_inode_blocks_set().
> This error should never happen in theory since sb->s_maxbytes should not
> have allowed this, we have already init sb->s_maxbytes according to this
> feature in ext4_fill_super(). So even through that could only happen due
> to the filesystem corruption, we'd better to return after we finish
> updating the inode because it may left an uninitialized buffer and we
> could read this buffer later in "errors=continue" mode.
> 
> This patch make the updating inode data procedure atomic, call
> EXT4_ERROR_INODE() after we dropping i_raw_lock after something bad
> happened, make sure that the inode is integrated, and also drop a BUG_ON
> and do some small cleanups.
> 
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>

Looks good! Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext4/inode.c | 44 ++++++++++++++++++++++++++++----------------
>  1 file changed, 28 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index eae1b2d0b550..8323d3e8f393 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4920,8 +4920,14 @@ static int ext4_inode_blocks_set(handle_t *handle,
>  		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
>  		return 0;
>  	}
> +
> +	/*
> +	 * This should never happen since sb->s_maxbytes should not have
> +	 * allowed this, sb->s_maxbytes was set according to the huge_file
> +	 * feature in ext4_fill_super().
> +	 */
>  	if (!ext4_has_feature_huge_file(sb))
> -		return -EFBIG;
> +		return -EFSCORRUPTED;
>  
>  	if (i_blocks <= 0xffffffffffffULL) {
>  		/*
> @@ -5024,16 +5030,14 @@ static int ext4_do_update_inode(handle_t *handle,
>  
>  	spin_lock(&ei->i_raw_lock);
>  
> -	/* For fields not tracked in the in-memory inode,
> -	 * initialise them to zero for new inodes. */
> +	/*
> +	 * For fields not tracked in the in-memory inode, initialise them
> +	 * to zero for new inodes.
> +	 */
>  	if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
>  		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
>  
>  	err = ext4_inode_blocks_set(handle, raw_inode, ei);
> -	if (err) {
> -		spin_unlock(&ei->i_raw_lock);
> -		goto out_brelse;
> -	}
>  
>  	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
>  	i_uid = i_uid_read(inode);
> @@ -5042,10 +5046,11 @@ static int ext4_do_update_inode(handle_t *handle,
>  	if (!(test_opt(inode->i_sb, NO_UID32))) {
>  		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
>  		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
> -/*
> - * Fix up interoperability with old kernels. Otherwise, old inodes get
> - * re-used with the upper 16 bits of the uid/gid intact
> - */
> +		/*
> +		 * Fix up interoperability with old kernels. Otherwise,
> +		 * old inodes get re-used with the upper 16 bits of the
> +		 * uid/gid intact.
> +		 */
>  		if (ei->i_dtime && list_empty(&ei->i_orphan)) {
>  			raw_inode->i_uid_high = 0;
>  			raw_inode->i_gid_high = 0;
> @@ -5114,8 +5119,9 @@ static int ext4_do_update_inode(handle_t *handle,
>  		}
>  	}
>  
> -	BUG_ON(!ext4_has_feature_project(inode->i_sb) &&
> -	       i_projid != EXT4_DEF_PROJID);
> +	if (i_projid != EXT4_DEF_PROJID &&
> +	    !ext4_has_feature_project(inode->i_sb))
> +		err = err ?: -EFSCORRUPTED;
>  
>  	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
>  	    EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
> @@ -5123,6 +5129,11 @@ static int ext4_do_update_inode(handle_t *handle,
>  
>  	ext4_inode_csum_set(inode, raw_inode, ei);
>  	spin_unlock(&ei->i_raw_lock);
> +	if (err) {
> +		EXT4_ERROR_INODE(inode, "corrupted inode contents");
> +		goto out_brelse;
> +	}
> +
>  	if (inode->i_sb->s_flags & SB_LAZYTIME)
>  		ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
>  					      bh->b_data);
> @@ -5130,13 +5141,13 @@ static int ext4_do_update_inode(handle_t *handle,
>  	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
>  	err = ext4_handle_dirty_metadata(handle, NULL, bh);
>  	if (err)
> -		goto out_brelse;
> +		goto out_error;
>  	ext4_clear_inode_state(inode, EXT4_STATE_NEW);
>  	if (set_large_file) {
>  		BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
>  		err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
>  		if (err)
> -			goto out_brelse;
> +			goto out_error;
>  		lock_buffer(EXT4_SB(sb)->s_sbh);
>  		ext4_set_feature_large_file(sb);
>  		ext4_superblock_csum_set(sb);
> @@ -5146,9 +5157,10 @@ static int ext4_do_update_inode(handle_t *handle,
>  						 EXT4_SB(sb)->s_sbh);
>  	}
>  	ext4_update_inode_fsync_trans(handle, inode, need_datasync);
> +out_error:
> +	ext4_std_error(inode->i_sb, err);
>  out_brelse:
>  	brelse(bh);
> -	ext4_std_error(inode->i_sb, err);
>  	return err;
>  }
>  
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR