Re: [PATCH v1] erofs-utils: don't hard code constants

From: Gao Xiang <hsiangkao@linux.alibaba.com>
To: Kelvin Zhang <zhangkelvin@google.com>
Cc: Miao Xie <miaoxie@huawei.com>,
	linux-erofs mailing list <linux-erofs@lists.ozlabs.org>
Subject: Re: [PATCH v1] erofs-utils: don't hard code constants
Date: Wed, 2 Feb 2022 10:19:21 +0800	[thread overview]
Message-ID: <YfnqKRr73WjaTvZA@B-P7TQMD6M-0146> (raw)
In-Reply-To: <CAOSmRzjL=ufHBCcyCxHArizdV8cr0mjuER1CBiYKm5G3CzK6wQ@mail.gmail.com>

On Tue, Feb 01, 2022 at 02:44:46PM -0800, Kelvin Zhang wrote:
> Thanks Gao! I'm reading compressed indices code recently. Is there any
> notes/sketches/design docs you can share with me regarding that?
> 

There are some kernel commit messages to describe the on-disk format:
ec8c24420501d4cf3ed495c4d026984194897276
b86269f43892316ef5a177d7180d09d101a46f22

And Yue Hu wrote his own notes about compacted indexes (in Chinese):
http://tjtech.me/erofs-compacted-index-generation.html

Hope they are useful! I know that may not enough, I will try to write
more this year.

Thanks,
Gao Xiang

> Happy Chinese New Year!
> 
> On Mon, Jan 31, 2022 at 6:51 PM Gao Xiang <hsiangkao@linux.alibaba.com> wrote:
> >
> > On Mon, Jan 31, 2022 at 10:43:27AM -0800, Kelvin Zhang wrote:
> > > Use sizeof(z_erofs_vle_decompressed_index) to compute legacy index count
> > >
> > > Test: th
> > > Signed-off-by: Kelvin Zhang <zhangkelvin@google.com>
> > > ---
> > >  lib/compress.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/lib/compress.c b/lib/compress.c
> > > index 98be7a2..c520a1e 100644
> > > --- a/lib/compress.c
> > > +++ b/lib/compress.c
> > > @@ -359,7 +359,7 @@ int z_erofs_convert_to_compacted_format(struct erofs_inode *inode,
> > >                                                          inode->xattr_isize) +
> > >                                 sizeof(struct z_erofs_map_header);
> > >       const unsigned int totalidx = (legacymetasize -
> > > -                                    Z_EROFS_LEGACY_MAP_HEADER_SIZE) / 8;
> > > +                                    Z_EROFS_LEGACY_MAP_HEADER_SIZE) / sizeof(struct z_erofs_vle_decompressed_index);
> >
> > It would be better to keep 80-char limit rule.
> >
> > Thanks, applied.
> >
> > Happy chinese new year!
> > Gao Xiang
> >
> > >       const unsigned int logical_clusterbits = inode->z_logical_clusterbits;
> > >       u8 *out, *in;
> > >       struct z_erofs_compressindex_vec cv[16];
> > > --
> > > 2.35.0.rc2.247.g8bbb082509-goog
> 
> 
> 
> -- 
> Sincerely,
> 
> Kelvin Zhang