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From: David Sterba <dsterba@suse.cz>
To: Gao Xiang <hsiangkao@aol.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Gao Xiang <gaoxiang25@huawei.com>, Jan Kara <jack@suse.cz>,
	Dave Chinner <david@fromorbit.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Miao Xie <miaoxie@huawei.com>,
	devel@driverdev.osuosl.org,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Amir Goldstein <amir73il@gmail.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Jaegeuk Kim <jaegeuk@kernel.org>, Theodore Ts'o <tytso@mit.edu>,
	Pavel Machek <pavel@denx.de>, David Sterba <dsterba@suse.cz>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-erofs@lists.ozlabs.org
Subject: Re: [PATCH v6 05/24] erofs: add inode operations
Date: Mon, 2 Sep 2019 15:43:29 +0200
Message-ID: <20190902134329.GU2752@twin.jikos.cz> (raw)
In-Reply-To: <20190901093326.GA6267@hsiangkao-HP-ZHAN-66-Pro-G1>

On Sun, Sep 01, 2019 at 05:34:00PM +0800, Gao Xiang wrote:
> > > +static int read_inode(struct inode *inode, void *data)
> > > +{
> > > +	struct erofs_vnode *vi = EROFS_V(inode);
> > > +	struct erofs_inode_v1 *v1 = data;
> > > +	const unsigned int advise = le16_to_cpu(v1->i_advise);
> > > +	erofs_blk_t nblks = 0;
> > > +
> > > +	vi->datamode = __inode_data_mapping(advise);
> > 
> > What is the deal with these magic underscores here and various
> > other similar helpers?
> 
> Fixed in
> https://lore.kernel.org/linux-fsdevel/20190901055130.30572-17-hsiangkao@aol.com/
> 
> underscores means 'internal' in my thought, it seems somewhat
> some common practice of Linux kernel, or some recent discussions
> about it?... I didn't notice these discussions...

I know about a few valid uses of the underscores:

* pattern where the __underscored version does not do locking, while the other
  does
* similarly for atomic and non-atomic version
* macro that needs to manipulate the argument name (like glue some
  prefix, so the macro does not have underscores and is supposed to be
  used instead of the function with underscores that needs the full name
  of a variable/constant/..
* underscore function takes a few more parameters to further tune the
  behaviour, but most users are fine with the defaults and that is
  provided as a function without underscores
* in case you have just one function of the kind, don't use the underscores

I can lookup examples if you're interested or if the brief description
is not sufficient. The list covers what I've seen and used, but the list
may be incomplete.

  parent reply index

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-02 12:53 [PATCH v6 00/24] erofs: promote erofs from staging Gao Xiang
2019-08-02 12:53 ` [PATCH v6 01/24] erofs: add on-disk layout Gao Xiang
2019-08-29  9:59   ` Christoph Hellwig
2019-08-29 10:32     ` Gao Xiang
2019-08-29 10:36       ` Christoph Hellwig
2019-08-29 10:58         ` Gao Xiang
2019-08-29 15:58       ` Joe Perches
2019-08-29 17:26         ` Gao Xiang
2019-08-30 12:07         ` David Sterba
2019-08-30 12:18           ` Gao Xiang
2019-09-02  8:43           ` Pavel Machek
2019-09-02 14:07             ` David Sterba
2019-09-03 11:27               ` Pavel Machek
2019-08-29 15:41     ` Gao Xiang
2019-09-01  7:54     ` Gao Xiang
2019-09-02 12:45       ` Christoph Hellwig
2019-09-02 13:02         ` Gao Xiang
2019-09-02  8:40     ` Pavel Machek
2019-09-02 10:35       ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 02/24] erofs: add erofs in-memory stuffs Gao Xiang
2019-08-02 12:53 ` [PATCH v6 03/24] erofs: add super block operations Gao Xiang
2019-08-29 10:15   ` Christoph Hellwig
2019-08-29 10:50     ` Gao Xiang
2019-08-30 16:39       ` Christoph Hellwig
2019-08-30 17:15         ` Gao Xiang
2019-08-31  0:54           ` Gao Xiang
2019-08-31  6:34           ` Amir Goldstein
2019-08-31  6:48             ` Gao Xiang
2019-09-01  8:54     ` Gao Xiang
2019-09-02 12:51       ` Christoph Hellwig
2019-09-02 14:43         ` Gao Xiang
2019-09-02 15:19           ` Christoph Hellwig
2019-09-02 15:24             ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 04/24] erofs: add raw address_space operations Gao Xiang
2019-08-29 10:17   ` Christoph Hellwig
2019-08-29 11:46     ` Gao Xiang
2019-08-30 16:40       ` Christoph Hellwig
2019-08-30 17:23         ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 05/24] erofs: add inode operations Gao Xiang
2019-08-29 10:24   ` Christoph Hellwig
2019-08-29 11:59     ` Gao Xiang
2019-08-30 16:42       ` Christoph Hellwig
2019-08-30 18:46         ` Gao Xiang
2019-09-01  9:34     ` Gao Xiang
2019-09-02 12:53       ` Christoph Hellwig
2019-09-02 13:43       ` David Sterba [this message]
2019-09-02 13:55         ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 06/24] erofs: support special inode Gao Xiang
2019-08-29 10:25   ` Christoph Hellwig
2019-09-01  9:39     ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 07/24] erofs: add directory operations Gao Xiang
2019-08-02 12:53 ` [PATCH v6 08/24] erofs: add namei functions Gao Xiang
2019-08-29 10:28   ` Christoph Hellwig
2019-08-29 11:28     ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 09/24] erofs: support tracepoint Gao Xiang
2019-08-02 12:53 ` [PATCH v6 10/24] erofs: update Kconfig and Makefile Gao Xiang
2019-08-02 12:53 ` [PATCH v6 11/24] erofs: introduce xattr & posixacl support Gao Xiang
2019-08-02 12:53 ` [PATCH v6 12/24] erofs: introduce tagged pointer Gao Xiang
2019-08-02 12:53 ` [PATCH v6 13/24] erofs: add compression indexes support Gao Xiang
2019-08-02 12:53 ` [PATCH v6 14/24] erofs: introduce superblock registration Gao Xiang
2019-08-02 12:53 ` [PATCH v6 15/24] erofs: introduce erofs shrinker Gao Xiang
2019-08-02 12:53 ` [PATCH v6 16/24] erofs: introduce workstation for decompression Gao Xiang
2019-08-02 12:53 ` [PATCH v6 17/24] erofs: introduce per-CPU buffers implementation Gao Xiang
2019-08-02 12:53 ` [PATCH v6 18/24] erofs: introduce pagevec for decompression subsystem Gao Xiang
2019-08-02 12:53 ` [PATCH v6 19/24] erofs: add erofs_allocpage() Gao Xiang
2019-08-02 12:53 ` [PATCH v6 20/24] erofs: introduce generic decompression backend Gao Xiang
2019-08-02 12:53 ` [PATCH v6 21/24] erofs: introduce LZ4 decompression inplace Gao Xiang
2019-08-02 12:53 ` [PATCH v6 22/24] erofs: introduce the decompression frontend Gao Xiang
2019-08-02 12:53 ` [PATCH v6 23/24] erofs: introduce cached decompression Gao Xiang
2019-08-02 12:53 ` [PATCH v6 24/24] erofs: add document Gao Xiang

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