linux-ext4 - Re: [PATCH 21/25] ext4: make online defragmentation support large block size

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Message-ID: <8041da1f-2ea6-4c66-8042-81076f5fc9d3@huaweicloud.com>
Date: Wed, 5 Nov 2025 18:48:41 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: Jan Kara <jack@...e.cz>, libaokun@...weicloud.com
Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca,
 linux-kernel@...r.kernel.org, kernel@...kajraghav.com, mcgrof@...nel.org,
 linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, yangerkun@...wei.com,
 chengzhihao1@...wei.com, libaokun1@...wei.com
Subject: Re: [PATCH 21/25] ext4: make online defragmentation support large
 block size

On 11/5/2025 5:50 PM, Jan Kara wrote:
> On Sat 25-10-25 11:22:17, libaokun@...weicloud.com wrote:
>> From: Zhihao Cheng <chengzhihao1@...wei.com>
>>
>> There are several places assuming that block size <= PAGE_SIZE, modify
>> them to support large block size (bs > ps).
>>
>> Signed-off-by: Zhihao Cheng <chengzhihao1@...wei.com>
>> Signed-off-by: Baokun Li <libaokun1@...wei.com>
> 
> ...
> 
>> @@ -565,7 +564,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
>>  	struct inode *orig_inode = file_inode(o_filp);
>>  	struct inode *donor_inode = file_inode(d_filp);
>>  	struct ext4_ext_path *path = NULL;
>> -	int blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits;
>> +	int blocks_per_page = 1;
>>  	ext4_lblk_t o_end, o_start = orig_blk;
>>  	ext4_lblk_t d_start = donor_blk;
>>  	int ret;
>> @@ -608,6 +607,9 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
>>  		return -EOPNOTSUPP;
>>  	}
>>  
>> +	if (i_blocksize(orig_inode) < PAGE_SIZE)
>> +		blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits;
>> +
> 
> I think these are strange and the only reason for this is that
> ext4_move_extents() tries to make life easier to move_extent_per_page() and
> that doesn't really work with larger folios anymore. I think
> ext4_move_extents() just shouldn't care about pages / folios at all and
> pass 'cur_len' as the length to the end of extent / moved range and
> move_extent_per_page() will trim the length based on the folios it has got.
> 
> Also then we can rename some of the variables and functions from 'page' to
> 'folio'.
> 
> 								Honza

Hi, Jan!

Thank you for the suggestion. However, after merging my online defragmentation
optimization series[1], we don't need this patch at all. Baokun will rebase it
onto my series in the next iteration.

[1] https://lore.kernel.org/linux-ext4/20251013015128.499308-1-yi.zhang@huaweicloud.com/

Thanks,
Yi.

> 
>>  	/* Protect orig and donor inodes against a truncate */
>>  	lock_two_nondirectories(orig_inode, donor_inode);
>>  
>> @@ -665,10 +667,8 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
>>  		if (o_end - o_start < cur_len)
>>  			cur_len = o_end - o_start;
>>  
>> -		orig_page_index = o_start >> (PAGE_SHIFT -
>> -					       orig_inode->i_blkbits);
>> -		donor_page_index = d_start >> (PAGE_SHIFT -
>> -					       donor_inode->i_blkbits);
>> +		orig_page_index = EXT4_LBLK_TO_P(orig_inode, o_start);
>> +		donor_page_index = EXT4_LBLK_TO_P(donor_inode, d_start);
>>  		offset_in_page = o_start % blocks_per_page;
>>  		if (cur_len > blocks_per_page - offset_in_page)
>>  			cur_len = blocks_per_page - offset_in_page;
>> -- 
>> 2.46.1
>>