linux-ext4 - Re: [PATCH v2 3/4] ext4: don't return error if huge

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Message-ID: <3bccf3af-8408-4a57-74a0-5d9fca85cf1e@huawei.com>
Date:   Thu, 19 Aug 2021 21:11:59 +0800
From:   Zhang Yi <yi.zhang@...wei.com>
To:     Jan Kara <jack@...e.cz>
CC:     <linux-ext4@...r.kernel.org>, <tytso@....edu>,
        <adilger.kernel@...ger.ca>, <yukuai3@...wei.com>
Subject: Re: [PATCH v2 3/4] ext4: don't return error if huge_file feature
 mismatch

On 2021/8/19 18:26, Jan Kara wrote:
> On Thu 19-08-21 14:57:03, Zhang Yi wrote:
>> In ext4_inode_blocks_set(), huge_file feature should exist when setting
>> i_blocks beyond a 32 bit variable could be represented, return EFBIG if
>> not. This error should never happen in theory since sb->s_maxbytes should
>> not have allowed this, and we have already init sb->s_maxbytes according
>> to this feature in ext4_fill_super(). So switch to use WARN_ON_ONCE
>> instead.
>>
>> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
>> ---
> 
> One comment below:
> 
>> @@ -4918,10 +4918,15 @@ static int ext4_inode_blocks_set(handle_t *handle,
>>  		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
>>  		raw_inode->i_blocks_high = 0;
>>  		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
>> -		return 0;
>> +		return;
>>  	}
>> -	if (!ext4_has_feature_huge_file(sb))
>> -		return -EFBIG;
>> +
>> +	/*
>> +	 * This should never happen since sb->s_maxbytes should not have
>> +	 * allowed this, which was set according to the huge_file feature
>> +	 * in ext4_fill_super().
>> +	 */
>> +	WARN_ON_ONCE(!ext4_has_feature_huge_file(sb));
> 
> Thinking about this a bit more, this could also happen due to fs
> corruption. So we probably need to call ext4_error_inode() here instead of
> WARN_ON_ONCE(). Also it will result in properly marking fs as having
> errors. But since we hold i_raw_lock at this call site we need to
> keep the error bail out from ext4_inode_blocks_set() and in
> ext4_do_update_inode() finish updating inode and then call
> ext4_error_inode() after dropping i_raw_lock.
> 
Yes, make sense, ext4_error_inode() is more reasonable.

Thanks,
Yi.