From: Gao Xiang <gaoxiang25@huawei.com>
To: Jan Kara <jack@suse.cz>
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>, "David Sterba" <dsterba@suse.cz>,
Amir Goldstein <amir73il@gmail.com>,
"Christoph Hellwig" <hch@infradead.org>,
"Darrick J . Wong" <darrick.wong@oracle.com>,
Dave Chinner <david@fromorbit.com>,
Jaegeuk Kim <jaegeuk@kernel.org>,
"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 v5 12/24] erofs: introduce tagged pointer
Date: Wed, 31 Jul 2019 21:30:04 +0800 [thread overview]
Message-ID: <560f56f4-fb6d-6c78-6080-fe32df9ac4bf@huawei.com> (raw)
In-Reply-To: <204b7fcc-a54b-ebd6-ff4c-2d5e2e6d4a8c@huawei.com>
On 2019/7/31 21:20, Gao Xiang wrote:
> Yes, I think that is about coding style, but the legacy way we have to do
> type cast as well, I think...
>
> struct b *ptr = tagptr_unfold_tags(tptr);
> vs
> struct b *ptr = (struct b *)((unsigned long)tptr & ~2);
and we could do "typedef tagptr1_t tptrb;" and then use tptrb for tagged
pointer rather than barely use tagptr1_t tagptr2_t ... as I mentioned in:
https://lore.kernel.org/lkml/0c2cdd4f-8fe7-6084-9c2d-c2e475e6806e@aol.com/
I think "tptrb" is enough for developers to know the original pointer type
when they coding...
OTOH, I think it could be better not to directly use "struct b *" to
represent the whole tagged pointer since it seems unsafe to do dereference
directly.. It could introduce some potential bugs...
All in all, this approach is only used for EROFS for now... If there are
some better implementation, I can switch to it in the later version :)
Thanks,
Gao Xiang
next prev parent reply other threads:[~2019-07-31 13:30 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 7:13 [PATCH v5 00/24] erofs: promote erofs from staging Gao Xiang
2019-07-30 7:13 ` [PATCH v5 01/24] erofs: add on-disk layout Gao Xiang
2019-07-30 7:13 ` [PATCH v5 02/24] erofs: add erofs in-memory stuffs Gao Xiang
2019-07-30 7:13 ` [PATCH v5 03/24] erofs: add super block operations Gao Xiang
2019-07-30 7:13 ` [PATCH v5 04/24] erofs: add raw address_space operations Gao Xiang
2019-07-30 7:13 ` [PATCH v5 05/24] erofs: add inode operations Gao Xiang
2019-07-30 7:13 ` [PATCH v5 06/24] erofs: support special inode Gao Xiang
2019-07-30 7:13 ` [PATCH v5 07/24] erofs: add directory operations Gao Xiang
2019-07-30 7:13 ` [PATCH v5 08/24] erofs: add namei functions Gao Xiang
2019-07-30 7:13 ` [PATCH v5 09/24] erofs: support tracepoint Gao Xiang
2019-07-30 7:13 ` [PATCH v5 10/24] erofs: update Kconfig and Makefile Gao Xiang
2019-07-30 7:14 ` [PATCH v5 11/24] erofs: introduce xattr & posixacl support Gao Xiang
2019-07-30 7:14 ` [PATCH v5 12/24] erofs: introduce tagged pointer Gao Xiang
2019-07-31 13:01 ` Jan Kara
2019-07-31 13:20 ` Gao Xiang
2019-07-31 13:30 ` Gao Xiang [this message]
2019-07-31 13:52 ` Gao Xiang
2019-07-30 7:14 ` [PATCH v5 13/24] erofs: add compression indexes support Gao Xiang
2019-07-30 7:14 ` [PATCH v5 14/24] erofs: introduce superblock registration Gao Xiang
2019-07-30 7:14 ` [PATCH v5 15/24] erofs: introduce erofs shrinker Gao Xiang
2019-07-30 7:14 ` [PATCH v5 16/24] erofs: introduce workstation for decompression Gao Xiang
2019-07-30 7:14 ` [PATCH v5 17/24] erofs: introduce per-CPU buffers implementation Gao Xiang
2019-07-30 7:14 ` [PATCH v5 18/24] erofs: introduce pagevec for decompression subsystem Gao Xiang
2019-07-30 7:14 ` [PATCH v5 19/24] erofs: add erofs_allocpage() Gao Xiang
2019-07-30 7:14 ` [PATCH v5 20/24] erofs: introduce generic decompression backend Gao Xiang
2019-07-30 7:14 ` [PATCH v5 21/24] erofs: introduce LZ4 decompression inplace Gao Xiang
2019-07-30 7:14 ` [PATCH v5 22/24] erofs: introduce the decompression frontend Gao Xiang
2019-07-30 7:14 ` [PATCH v5 23/24] erofs: introduce cached decompression Gao Xiang
2019-07-30 7:14 ` [PATCH v5 24/24] erofs: add document Gao Xiang
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