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Subject: Re: [f2fs-dev] [PATCH v5 RESEND] f2fs: compress: add compress_inode
 to cache compressed blocks
To:     Eric Biggers <ebiggers@kernel.org>
CC:     <jaegeuk@kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>
References: <20201207095220.73093-1-yuchao0@huawei.com>
 <X85wshahXe4nR+N6@gmail.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <8cccbe7f-94c0-ddd0-4da5-234d02839ae0@huawei.com>
Date:   Tue, 8 Dec 2020 08:59:12 +0800
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On 2020/12/8 2:13, Eric Biggers wrote:
> On Mon, Dec 07, 2020 at 05:52:20PM +0800, Chao Yu wrote:
>> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
>> index dae15c96e659..fd413d319e93 100644
>> --- a/Documentation/filesystems/f2fs.rst
>> +++ b/Documentation/filesystems/f2fs.rst
>> @@ -268,6 +268,9 @@ compress_mode=%s	 Control file compression mode. This supports "fs" and "user"
>>   			 choosing the target file and the timing. The user can do manual
>>   			 compression/decompression on the compression enabled files using
>>   			 ioctls.
>> +compress_cache		 Support to use address space of inner inode to cache
>> +			 compressed block, in order to improve cache hit ratio of
>> +			 random read.
> 
> What is an "inner inode"?  Mount options should be understandable without
> understanding filesystem implementation details.

I'd like to use "a filesystem managed inode" instead, if there is no further
comment.

> 
>> +const struct address_space_operations f2fs_compress_aops = {
>> +	.releasepage = f2fs_release_page,
>> +	.invalidatepage = f2fs_invalidate_page,
>> +};
>> +
>> +struct address_space *COMPRESS_MAPPING(struct f2fs_sb_info *sbi)
>> +{
>> +	return sbi->compress_inode->i_mapping;
>> +}
>> +
>> +void invalidate_compress_page(struct f2fs_sb_info *sbi, block_t blkaddr)
>> +{
>> +	if (!sbi->compress_inode)
>> +		return;
>> +	invalidate_mapping_pages(COMPRESS_MAPPING(sbi), blkaddr, blkaddr);
>> +}
> 
> Global functions should have the "f2fs_" prefix.

Yup,

Thanks,

> 
> - Eric
> .
>