Re: [f2fs-dev] [PATCH v5 RESEND] f2fs: compress: add compress_inode to cache compressed blocks

[Chao Yu]

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
> .