linux-kernel - Re: [PATCH v4 1/2] erofs: avoid hardcoded blocksize for subpage block support

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Message-ID: <19551cbd-f4b9-b53a-bbfb-08c88b81321b@linux.alibaba.com>
Date:   Mon, 6 Mar 2023 17:45:01 +0800
From:   Jingbo Xu <jefflexu@...ux.alibaba.com>
To:     Yue Hu <zbestahu@...il.com>
Cc:     xiang@...nel.org, chao@...nel.org, linux-erofs@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, huyue2@...lpad.com,
        zhangwen@...lpad.com
Subject: Re: [PATCH v4 1/2] erofs: avoid hardcoded blocksize for subpage block
 support



On 3/6/23 3:16 PM, Yue Hu wrote:
> On Thu,  2 Mar 2023 22:39:14 +0800
> Jingbo Xu <jefflexu@...ux.alibaba.com> wrote:
> 
>> As the first step of converting hardcoded blocksize to that specified in
>> on-disk superblock, convert all call sites of hardcoded blocksize to
>> sb->s_blocksize except for:
>>
>> 1) use sbi->blkszbits instead of sb->s_blocksize in
>> erofs_superblock_csum_verify() since sb->s_blocksize has not been
>> updated with the on-disk blocksize yet when the function is called.
>>
>> 2) use inode->i_blkbits instead of sb->s_blocksize in erofs_bread(),
>> since the inode operated on may be an anonymous inode in fscache mode.
>> Currently the anonymous inode is allocated from an anonymous mount
>> maintained in erofs, while in the near future we may allocate anonymous
>> inodes from a generic API directly and thus have no access to the
>> anonymous inode's i_sb.  Thus we keep the block size in i_blkbits for
>> anonymous inodes in fscache mode.
>>
>> Be noted that this patch only gets rid of the hardcoded blocksize, in
>> preparation for actually setting the on-disk block size in the following
>> patch.  The hard limit of constraining the block size to PAGE_SIZE still
>> exists until the next patch.
>>
>> Signed-off-by: Jingbo Xu <jefflexu@...ux.alibaba.com>
>> Reviewed-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
>> ---
>> diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
>> index 51b7ac7166d9..21fc6897d225 100644
>> --- a/fs/erofs/decompressor.c
>> +++ b/fs/erofs/decompressor.c
>> @@ -42,7 +42,7 @@ int z_erofs_load_lz4_config(struct super_block *sb,
>>  		if (!sbi->lz4.max_pclusterblks) {
>>  			sbi->lz4.max_pclusterblks = 1;	/* reserved case */
>>  		} else if (sbi->lz4.max_pclusterblks >
>> -			   Z_EROFS_PCLUSTER_MAX_SIZE / EROFS_BLKSIZ) {
>> +			   Z_EROFS_PCLUSTER_MAX_SIZE >> sb->s_blocksize_bits) {
> 
> erofs_blknr(sb, Z_EROFS_PCLUSTER_MAX_SIZE)?

Okay.

>> @@ -422,7 +423,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
>>  		return -EFSCORRUPTED;
>>  	}
>>  out:
>> -	map->m_plen = (u64)m->compressedblks << LOG_BLOCK_SIZE;
>> +	map->m_plen = (u64)m->compressedblks << sb->s_blocksize_bits;
> 
> erofs_pos(sb, m->compressedblks)?

Okay.  I will update all these in the next version.

Thanks for the comment!


-- 
Thanks,
Jingbo