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From: Gao Xiang <hsiangkao@aol.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: 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: Sun, 1 Sep 2019 17:34:00 +0800
Message-ID: <20190901093326.GA6267@hsiangkao-HP-ZHAN-66-Pro-G1> (raw)
In-Reply-To: <20190829102426.GE20598@infradead.org>

Hi Christoph,

Here are redo-ed comments of your suggestions...

On Thu, Aug 29, 2019 at 03:24:26AM -0700, Christoph Hellwig wrote:
> On Fri, Aug 02, 2019 at 08:53:28PM +0800, Gao Xiang wrote:
> > This adds core functions to get, read an inode.
> > It adds statx support as well.
> > 
> > Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
> > ---
> >  fs/erofs/inode.c | 291 +++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 291 insertions(+)
> >  create mode 100644 fs/erofs/inode.c
> > 
> > diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> > new file mode 100644
> > index 000000000000..b6ea997bc4ae
> > --- /dev/null
> > +++ b/fs/erofs/inode.c
> > @@ -0,0 +1,291 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * linux/fs/erofs/inode.c
> > + *
> > + * Copyright (C) 2017-2018 HUAWEI, Inc.
> > + *             http://www.huawei.com/
> > + * Created by Gao Xiang <gaoxiang25@huawei.com>
> > + */
> > +#include "internal.h"
> > +
> > +#include <trace/events/erofs.h>
> > +
> > +/* no locking */
> > +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...

> 
> > +	/* fast symlink (following ext4) */
> 
> This actually originates in FFS.  But it is so common that the comment
> seems a little pointless.

Fixed in
https://lore.kernel.org/linux-fsdevel/20190901055130.30572-9-hsiangkao@aol.com/

> 
> > +	if (S_ISLNK(inode->i_mode) && inode->i_size < PAGE_SIZE) {
> > +		char *lnk = erofs_kmalloc(sbi, inode->i_size + 1, GFP_KERNEL);
> 
> Please just use plain kmalloc everywhere and let the normal kernel
> error injection code take care of injeting any errors.

Fixed in
https://lore.kernel.org/linux-fsdevel/20190901055130.30572-20-hsiangkao@aol.com/

> 
> > +		/* inline symlink data shouldn't across page boundary as well */
> 
> ... should not cross ..

Fixed in
https://lore.kernel.org/linux-fsdevel/20190901055130.30572-9-hsiangkao@aol.com/

> 
> > +		if (unlikely(m_pofs + inode->i_size > PAGE_SIZE)) {
> > +			DBG_BUGON(1);
> > +			kfree(lnk);
> > +			return -EIO;
> > +		}
> > +
> > +		/* get in-page inline data */
> 
> s/get/copy/, but the comment seems rather pointless.

Fixed in
https://lore.kernel.org/linux-fsdevel/20190901055130.30572-9-hsiangkao@aol.com/

> 
> > +		memcpy(lnk, data + m_pofs, inode->i_size);
> > +		lnk[inode->i_size] = '\0';
> > +
> > +		inode->i_link = lnk;
> > +		set_inode_fast_symlink(inode);
> 
> Please just set the ops directly instead of obsfucating that in a single
> caller, single line inline function.  And please set it instead of the
> normal symlink iops in the same place where you also set those.:w

Fixed in
https://lore.kernel.org/linux-fsdevel/20190901055130.30572-10-hsiangkao@aol.com/

> 
> > +	err = read_inode(inode, data + ofs);
> > +	if (!err) {
> 
> 	if (err)
> 		goto out_unlock;
> 
> .. and save one level of indentation.

Fixed in
https://lore.kernel.org/linux-fsdevel/20190901055130.30572-22-hsiangkao@aol.com/

> 
> > +		if (is_inode_layout_compression(inode)) {
> 
> The name of this helper is a little odd.  But I think just
> opencoding it seems generally cleaner anyway.

Fixed in
https://lore.kernel.org/linux-fsdevel/20190901055130.30572-11-hsiangkao@aol.com/

> 
> 
> > +			err = -ENOTSUPP;
> > +			goto out_unlock;
> > +		}
> > +
> > +		inode->i_mapping->a_ops = &erofs_raw_access_aops;
> > +
> > +		/* fill last page if inline data is available */
> > +		err = fill_inline_data(inode, data, ofs);
> 
> Well, I think you should move the is_inode_flat_inline and
> (S_ISLNK(inode->i_mode) && inode->i_size < PAGE_SIZE) checks from that
> helper here, as otherwise you make everyone wonder why you'd always
> fill out the inline data.

fill_inline_data is killed, and the similar function turns into
erofs_fill_symlink which is called at erofs_fill_inode():

 		case S_IFLNK:
-			/* by default, page_get_link is used for symlink */
-			inode->i_op = &erofs_symlink_iops;
+			err = erofs_fill_symlink(inode, data, ofs);
+			if (err)
+				goto out_unlock;
 			inode_nohighmem(inode);
 			break;

> 
> > +static inline struct inode *erofs_iget_locked(struct super_block *sb,
> > +					      erofs_nid_t nid)
> > +{
> > +	const unsigned long hashval = erofs_inode_hash(nid);
> > +
> > +#if BITS_PER_LONG >= 64
> > +	/* it is safe to use iget_locked for >= 64-bit platform */
> > +	return iget_locked(sb, hashval);
> > +#else
> > +	return iget5_locked(sb, hashval, erofs_ilookup_test_actor,
> > +		erofs_iget_set_actor, &nid);
> > +#endif
> 
> Just use the slightly more complicated 32-bit version everywhere so that
> you have a single actually tested code path.  And then remove this
> helper.

As I said before, 64-bit platforms is common currently,
I think iget_locked is enough.
https://lore.kernel.org/r/20190830184606.GA175612@architecture4/

Thanks,
Gao Xiang




  parent 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
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 [this message]
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

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