Linux-Fsdevel Archive on lore.kernel.org
 help / color / Atom feed
From: Gao Xiang <gaoxiang25@huawei.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Theodore Ts'o <tytso@mit.edu>, "Pavel Machek" <pavel@denx.de>,
	David Sterba <dsterba@suse.cz>,
	Amir Goldstein <amir73il@gmail.com>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	"Dave Chinner" <david@fromorbit.com>,
	Jaegeuk Kim <jaegeuk@kernel.org>, Jan Kara <jack@suse.cz>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	<linux-fsdevel@vger.kernel.org>, <devel@driverdev.osuosl.org>,
	LKML <linux-kernel@vger.kernel.org>,
	<linux-erofs@lists.ozlabs.org>, Chao Yu <yuchao0@huawei.com>,
	Miao Xie <miaoxie@huawei.com>,
	Li Guifu <bluce.liguifu@huawei.com>,
	Fang Wei <fangwei1@huawei.com>
Subject: Re: [PATCH v6 03/24] erofs: add super block operations
Date: Thu, 29 Aug 2019 18:50:48 +0800
Message-ID: <20190829105048.GB64893@architecture4> (raw)
In-Reply-To: <20190829101545.GC20598@infradead.org>

Hi Christoph,

On Thu, Aug 29, 2019 at 03:15:45AM -0700, Christoph Hellwig wrote:
> On Fri, Aug 02, 2019 at 08:53:26PM +0800, Gao Xiang wrote:
> > +static int __init erofs_init_inode_cache(void)
> > +{
> > +	erofs_inode_cachep = kmem_cache_create("erofs_inode",
> > +					       sizeof(struct erofs_vnode), 0,
> > +					       SLAB_RECLAIM_ACCOUNT,
> > +					       init_once);
> > +
> > +	return erofs_inode_cachep ? 0 : -ENOMEM;
> 
> Please just use normal if/else.  Also having this function seems
> entirely pointless.
> 
> > +static void erofs_exit_inode_cache(void)
> > +{
> > +	kmem_cache_destroy(erofs_inode_cachep);
> > +}
> 
> Same for this one.
> 
> > +static void free_inode(struct inode *inode)
> 
> Please use an erofs_ prefix for all your functions.

It is already a static function, I have no idea what is wrong here.

> 
> > +{
> > +	struct erofs_vnode *vi = EROFS_V(inode);
> 
> Why is this called vnode instead of inode?  That seems like a rather
> odd naming for a Linux file system.

I don't know anything difference of that, it is just a naming.

> 
> > +
> > +	/* be careful RCU symlink path (see ext4_inode_info->i_data)! */
> > +	if (is_inode_fast_symlink(inode))
> > +		kfree(inode->i_link);
> 
> is_inode_fast_symlink only shows up in a later patch.  And really
> obsfucates the check here in the only caller as you can just do an
> unconditional kfree here - i_link will be NULL except for the case
> where you explicitly set it.

I cannot fully understand your point (sorry about my English),
I will reply you about this later.

> 
> Also this code is nothing like ext4, so the code seems a little confusing.
> 
> > +static bool check_layout_compatibility(struct super_block *sb,
> > +				       struct erofs_super_block *layout)
> > +{
> > +	const unsigned int requirements = le32_to_cpu(layout->requirements);
> 
> Why is the variable name for the on-disk subperblock layout?  We usually
> still calls this something with sb in the name, e.g. dsb. for disk
> super block.

I can change it later, sbi and dsb (It has not good meaning in Chinese, although).

> 
> > +	EROFS_SB(sb)->requirements = requirements;
> > +
> > +	/* check if current kernel meets all mandatory requirements */
> > +	if (requirements & (~EROFS_ALL_REQUIREMENTS)) {
> > +		errln("unidentified requirements %x, please upgrade kernel version",
> > +		      requirements & ~EROFS_ALL_REQUIREMENTS);
> > +		return false;
> > +	}
> > +	return true;
> 
> Note that normally we call this features, but that doesn't really
> matter too much.
> 
> > +static int superblock_read(struct super_block *sb)
> > +{
> > +	struct erofs_sb_info *sbi;
> > +	struct buffer_head *bh;
> > +	struct erofs_super_block *layout;
> > +	unsigned int blkszbits;
> > +	int ret;
> > +
> > +	bh = sb_bread(sb, 0);
> 
> Is there any good reasons to use buffer heads like this in new code
> vs directly using bios?

This page can save in bdev page cache, it contains not only the erofs
superblock so it can be fetched in page cache later.

> 
> > +
> > +	sbi->blocks = le32_to_cpu(layout->blocks);
> > +	sbi->meta_blkaddr = le32_to_cpu(layout->meta_blkaddr);
> > +	sbi->islotbits = ffs(sizeof(struct erofs_inode_v1)) - 1;
> > +	sbi->root_nid = le16_to_cpu(layout->root_nid);
> > +	sbi->inos = le64_to_cpu(layout->inos);
> > +
> > +	sbi->build_time = le64_to_cpu(layout->build_time);
> > +	sbi->build_time_nsec = le32_to_cpu(layout->build_time_nsec);
> > +
> > +	memcpy(&sb->s_uuid, layout->uuid, sizeof(layout->uuid));
> > +	memcpy(sbi->volume_name, layout->volume_name,
> > +	       sizeof(layout->volume_name));
> 
> s_uuid should preferably be a uuid_t (assuming it is a real BE uuid,
> if it is le it should be a guid_t).

I just copied it from f2fs, I have no idea which one is best and
which fs I could refer to.

> 
> > +/* set up default EROFS parameters */
> > +static void default_options(struct erofs_sb_info *sbi)
> > +{
> > +}
> 
> No need to add an empty function.

Later patch will fill this function.

> 
> > +static int erofs_fill_super(struct super_block *sb, void *data, int silent)
> > +{
> > +	struct inode *inode;
> > +	struct erofs_sb_info *sbi;
> > +	int err;
> > +
> > +	infoln("fill_super, device -> %s", sb->s_id);
> > +	infoln("options -> %s", (char *)data);
> 
> That is some very verbose debug info.  We usually don't add that and
> let people trace the function instead.  Also you should probably
> implement the new mount API.
> new mount API.

Al think it is not urgent as well,
https://lore.kernel.org/driverdev-devel/20190721040547.GF17978@ZenIV.linux.org.uk/

 Al said,
 >> I agree with you, it seems better to just use s_id in community and
 >> delete erofs_mount_private stuffs...
 >> Yet I don't look into how to use new fs_context, could I keep using
 >> legacy mount interface and fix them all?
 >
 > Sure.

> 
> > +static void erofs_kill_sb(struct super_block *sb)
> > +{
> > +	struct erofs_sb_info *sbi;
> > +
> > +	WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
> > +	infoln("unmounting for %s", sb->s_id);
> > +
> > +	kill_block_super(sb);
> > +
> > +	sbi = EROFS_SB(sb);
> > +	if (!sbi)
> > +		return;
> > +	kfree(sbi);
> > +	sb->s_fs_info = NULL;
> > +}
> 
> Why is this needed?  You can just free your sb privatte information in
> ->put_super and wire up kill_block_super as the ->kill_sb method
> directly.

See Al's comments,
https://lore.kernel.org/r/20190720224955.GD17978@ZenIV.linux.org.uk/

Thanks,
Gao Xiang


  reply index

Thread overview: 159+ 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 [this message]
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
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
2019-09-01  5:51 ` [PATCH 00/21] erofs: patchset addressing Christoph's comments Gao Xiang
2019-09-01  5:51   ` [PATCH 01/21] erofs: remove all the byte offset comments Gao Xiang
2019-09-02 12:05     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 02/21] erofs: on-disk format should have explicitly assigned numbers Gao Xiang
2019-09-02 12:05     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 03/21] erofs: some macros are much more readable as a function Gao Xiang
2019-09-02 12:06     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 04/21] erofs: kill __packed for on-disk structures Gao Xiang
2019-09-02 12:06     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 05/21] erofs: update erofs_inode_is_data_compressed helper Gao Xiang
2019-09-02 12:07     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 06/21] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang
2019-09-02 12:09     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 07/21] erofs: use erofs_inode naming Gao Xiang
2019-09-02 12:10     ` Christoph Hellwig
2019-09-02 12:13       ` Gao Xiang
2019-09-02 12:47         ` Christoph Hellwig
2019-09-02 13:33           ` Gao Xiang
2019-09-01  5:51   ` [PATCH 08/21] erofs: update comments in inode.c Gao Xiang
2019-09-01  5:51   ` [PATCH 09/21] erofs: update erofs symlink stuffs Gao Xiang
2019-09-02 12:11     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 10/21] erofs: kill is_inode_layout_compression() Gao Xiang
2019-09-02 12:11     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 11/21] erofs: use dsb instead of layout for ondisk super_block Gao Xiang
2019-09-02 12:12     ` Christoph Hellwig
2019-09-02 12:15       ` Gao Xiang
2019-09-01  5:51   ` [PATCH 12/21] erofs: kill verbose debug info in erofs_fill_super Gao Xiang
2019-09-02 12:14     ` Christoph Hellwig
2019-09-02 12:18       ` Gao Xiang
2019-09-01  5:51   ` [PATCH 13/21] erofs: simplify erofs_grab_bio() since bio_alloc() never fail Gao Xiang
2019-09-02 12:20     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 14/21] erofs: kill prio and nofail of erofs_get_meta_page() Gao Xiang
2019-09-02 12:21     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 15/21] erofs: kill __submit_bio() Gao Xiang
2019-09-01  5:51   ` [PATCH 16/21] erofs: kill magic underscores Gao Xiang
2019-09-02 12:26     ` Christoph Hellwig
2019-09-02 12:39       ` Gao Xiang
2019-09-02 12:54         ` Christoph Hellwig
2019-09-02 13:38           ` Gao Xiang
2019-09-01  5:51   ` [PATCH 17/21] erofs: use a switch statement when dealing with the file modes Gao Xiang
2019-09-02 12:27     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 18/21] erofs: add "erofs_" prefix for common and short functions Gao Xiang
2019-09-02 12:28     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 19/21] erofs: kill all erofs specific fault injection Gao Xiang
2019-09-02 12:28     ` Christoph Hellwig
2019-09-01  5:51   ` [PATCH 20/21] erofs: kill use_vmap module parameter Gao Xiang
2019-09-02 12:31     ` Christoph Hellwig
2019-09-02 12:43       ` Gao Xiang
2019-09-01  5:51   ` [PATCH 21/21] erofs: save one level of indentation Gao Xiang
2019-09-02 12:31     ` Christoph Hellwig
2019-09-02 12:46   ` [PATCH 00/21] erofs: patchset addressing Christoph's comments Christoph Hellwig
2019-09-02 14:24     ` Gao Xiang
2019-09-02 15:23       ` Christoph Hellwig
2019-09-02 15:50         ` Gao Xiang
2019-09-03  6:58           ` Christoph Hellwig
2019-09-03  8:17             ` Gao Xiang
2019-09-03 15:37               ` Christoph Hellwig
2019-09-03 15:43                 ` Gao Xiang
2019-09-04  2:08   ` [PATCH v2 00/25] " Gao Xiang
2019-09-04  2:08     ` [PATCH v2 01/25] erofs: remove all the byte offset comments Gao Xiang
2019-09-04  2:08     ` [PATCH v2 02/25] erofs: on-disk format should have explicitly assigned numbers Gao Xiang
2019-09-04  2:08     ` [PATCH v2 03/25] erofs: some macros are much more readable as a function Gao Xiang
2019-09-04  2:08     ` [PATCH v2 04/25] erofs: kill __packed for on-disk structures Gao Xiang
2019-09-04  2:08     ` [PATCH v2 05/25] erofs: update erofs_inode_is_data_compressed helper Gao Xiang
2019-09-04  2:08     ` [PATCH v2 06/25] erofs: use feature_incompat rather than requirements Gao Xiang
2019-09-04  2:08     ` [PATCH v2 07/25] erofs: better naming for erofs inode related stuffs Gao Xiang
2019-09-04  2:08     ` [PATCH v2 08/25] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang
2019-09-04  2:08     ` [PATCH v2 09/25] erofs: use erofs_inode naming Gao Xiang
2019-09-04  2:08     ` [PATCH v2 10/25] erofs: update erofs_fs.h comments Gao Xiang
2019-09-04  2:08     ` [PATCH v2 11/25] erofs: update comments in inode.c Gao Xiang
2019-09-04  2:08     ` [PATCH v2 12/25] erofs: better erofs symlink stuffs Gao Xiang
2019-09-04  2:09     ` [PATCH v2 13/25] erofs: use dsb instead of layout for ondisk super_block Gao Xiang
2019-09-04  2:09     ` [PATCH v2 14/25] erofs: kill verbose debug info in erofs_fill_super Gao Xiang
2019-09-04  2:09     ` [PATCH v2 15/25] erofs: localize erofs_grab_bio() Gao Xiang
2019-09-04  2:09     ` [PATCH v2 16/25] erofs: kill prio and nofail of erofs_get_meta_page() Gao Xiang
2019-09-04  2:09     ` [PATCH v2 17/25] erofs: kill __submit_bio() Gao Xiang
2019-09-04  2:09     ` [PATCH v2 18/25] erofs: add "erofs_" prefix for common and short functions Gao Xiang
2019-09-04  2:09     ` [PATCH v2 19/25] erofs: kill all erofs specific fault injection Gao Xiang
2019-09-04  2:09     ` [PATCH v2 20/25] erofs: kill use_vmap module parameter Gao Xiang
2019-09-04  2:09     ` [PATCH v2 21/25] erofs: save one level of indentation Gao Xiang
2019-09-04  2:09     ` [PATCH v2 22/25] erofs: rename errln/infoln/debugln to erofs_{err,info,dbg} Gao Xiang
2019-09-04  2:09     ` [PATCH v2 23/25] erofs: use read_mapping_page instead of sb_bread Gao Xiang
2019-09-04  2:09     ` [PATCH v2 24/25] erofs: always use iget5_locked Gao Xiang
2019-09-04  2:09     ` [PATCH v2 25/25] erofs: use read_cache_page_gfp for erofs_get_meta_page Gao Xiang
2019-09-04  3:27     ` [PATCH v2 00/25] erofs: patchset addressing Christoph's comments Chao Yu
2019-09-05  1:03       ` Gao Xiang
2019-09-05 11:30         ` Christoph Hellwig
2019-09-04  5:16     ` Christoph Hellwig
2019-09-04  6:08       ` Gao Xiang

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190829105048.GB64893@architecture4 \
    --to=gaoxiang25@huawei.com \
    --cc=akpm@linux-foundation.org \
    --cc=amir73il@gmail.com \
    --cc=bluce.liguifu@huawei.com \
    --cc=darrick.wong@oracle.com \
    --cc=david@fromorbit.com \
    --cc=devel@driverdev.osuosl.org \
    --cc=dsterba@suse.cz \
    --cc=fangwei1@huawei.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hch@infradead.org \
    --cc=jack@suse.cz \
    --cc=jaegeuk@kernel.org \
    --cc=linux-erofs@lists.ozlabs.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=miaoxie@huawei.com \
    --cc=pavel@denx.de \
    --cc=sfr@canb.auug.org.au \
    --cc=torvalds@linux-foundation.org \
    --cc=tytso@mit.edu \
    --cc=viro@zeniv.linux.org.uk \
    --cc=yuchao0@huawei.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Fsdevel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-fsdevel/0 linux-fsdevel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-fsdevel linux-fsdevel/ https://lore.kernel.org/linux-fsdevel \
		linux-fsdevel@vger.kernel.org
	public-inbox-index linux-fsdevel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-fsdevel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git