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Date:   Mon, 29 Mar 2021 14:55:49 +0800
From:   Gao Xiang <hsiangkao@redhat.com>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     Gao Xiang <hsiangkao@aol.com>, linux-erofs@lists.ozlabs.org,
        Chao Yu <chao@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] erofs: add on-disk compression configurations
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On Mon, Mar 29, 2021 at 02:43:48PM +0800, Chao Yu wrote:

...

> > > > +
> > > > +static int erofs_load_compr_cfgs(struct super_block *sb,
> > > > +				 struct erofs_super_block *dsb)
> > > > +{
> > > > +	struct erofs_sb_info *sbi;
> > > > +	struct page *page;
> > > > +	unsigned int algs, alg;
> > > > +	erofs_off_t offset;
> > > > +	int size, ret;
> > > > +
> > > > +	sbi = EROFS_SB(sb);
> > > > +	sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);
> > > > +
> > > > +	if (sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS) {
> > > > +		erofs_err(sb,
> > > > +"try to load compressed image with unsupported algorithms %x",
> > > 
> > > Minor style issue:
> > > 
> > > 			"try to load compressed image with unsupported "
> > > 			"algorithms %x",
> > > 			sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS);
> > 
> > If I remembered correctly, kernel code style suggests "don't break the print
> > message, it'd more easy to grep". Actually such style above is from XFS, and
> > can pass checkpatch.pl check, see:
> > 
> > (fs/xfs/xfs_log_recover.c) xlog_recover():
> > 		/*
> > 		 * Version 5 superblock log feature mask validation. We know the
> > 		 * log is dirty so check if there are any unknown log features
> > 		 * in what we need to recover. If there are unknown features
> > 		 * (e.g. unsupported transactions, then simply reject the
> > 		 * attempt at recovery before touching anything.
> > 		 */
> > 		if (XFS_SB_VERSION_NUM(&log->l_mp->m_sb) == XFS_SB_VERSION_5 &&
> > 		    xfs_sb_has_incompat_log_feature(&log->l_mp->m_sb,
> > 					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN)) {
> > 			xfs_warn(log->l_mp,
> > "Superblock has unknown incompatible log features (0x%x) enabled.",
> > 				(log->l_mp->m_sb.sb_features_log_incompat &
> > 					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN));
> > 			xfs_warn(log->l_mp,
> > "The log can not be fully and/or safely recovered by this kernel.");
> > 			xfs_warn(log->l_mp,
> > "Please recover the log on a kernel that supports the unknown features.");
> > 			return -EINVAL;
> > 		}
> > 
> > If that does't look ok for us, I could use > 80 line for this instead,
> > but I tend to not break the message ..
> 
> Xiang,
> 
> Ah, I didn't notice this is following above style, if it's fine to you,
> let's use some tabs in front of message line, though it will cause
> exceeding 80 line warning.
> 

I found a reference here,
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v5.11#n99
also vaguely remembered some threads from Linus, but hard to find now :-(

ok, I will insert tabs instead, thanks for the suggestion!

Thanks,
Gao Xiang


> Thanks,