From: Gao Xiang <gaoxiang25@huawei.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Joe Perches <joe@perches.com>, Chao Yu <yuchao0@huawei.com>,
Dan Carpenter <dan.carpenter@oracle.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
<devel@driverdev.osuosl.org>, LKML <linux-kernel@vger.kernel.org>,
<linux-erofs@lists.ozlabs.org>, Chao Yu <chao@kernel.org>,
Miao Xie <miaoxie@huawei.com>, <weidu.du@huawei.com>,
Fang Wei <fangwei1@huawei.com>
Subject: Re: [PATCH v2 2/7] erofs: some marcos are much more readable as a function
Date: Fri, 30 Aug 2019 23:52:23 +0800 [thread overview]
Message-ID: <20190830155223.GA69026@architecture4> (raw)
In-Reply-To: <20190830154551.GA11571@infradead.org>
Hi Christoph,
On Fri, Aug 30, 2019 at 08:45:51AM -0700, Christoph Hellwig wrote:
> On Thu, Aug 29, 2019 at 08:16:27PM -0700, Joe Perches wrote:
> > > - sizeof(__u32) * ((__count) - 1); })
> > > +static inline unsigned int erofs_xattr_ibody_size(__le16 d_icount)
> > > +{
> > > + unsigned int icount = le16_to_cpu(d_icount);
> > > +
> > > + if (!icount)
> > > + return 0;
> > > +
> > > + return sizeof(struct erofs_xattr_ibody_header) +
> > > + sizeof(__u32) * (icount - 1);
> >
> > Maybe use struct_size()?
>
> Declaring a variable that is only used for struct_size is rather ugly.
> But while we are nitpicking: you don't need to byteswap to check for 0,
> so the local variable could be avoided.
>
> Also what is that magic -1 for? Normally we use that for the
> deprecated style where a variable size array is declared using
> varname[1], but that doesn't seem to be the case for erofs.
I have to explain more about this (sorry about my awkward English)
here i_xattr_icount is to represent the size of xattr field of erofs, as follows:
0 - no xattr at all (no erofs_xattr_ibody_header)
_______
| inode |
|_______|
1 - a erofs_xattr_ibody_header (12 byte) + 4-byte (shared + inline) xattrs
2 - a erofs_xattr_ibody_header (12 byte) + 8-byte (shared + inline) xattrs
....
(that is the magic -1 means...)
In order to keep the number continuously, actually the content could be
an array of shared_xattr_id and
an inline xattr combination (struct erofs_xattr_entry + name + value)
Thanks,
Gao Xiang
next prev parent reply other threads:[~2019-08-30 15:53 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-30 3:00 [PATCH v2 1/7] erofs: on-disk format should have explicitly assigned numbers Gao Xiang
2019-08-30 3:00 ` [PATCH v2 2/7] erofs: some marcos are much more readable as a function Gao Xiang
2019-08-30 3:16 ` Joe Perches
2019-08-30 3:20 ` Gao Xiang
2019-08-30 3:36 ` [PATCH v3 1/7] erofs: on-disk format should have explicitly assigned numbers Gao Xiang
2019-08-30 3:36 ` [PATCH v3 2/7] erofs: some macros are much more readable as a function Gao Xiang
2019-08-30 3:38 ` [PATCH v4 " Gao Xiang
2019-08-30 6:11 ` [PATCH v3 " Chao Yu
2019-08-30 3:36 ` [PATCH v3 3/7] erofs: use a better form for complicated on-disk fields Gao Xiang
2019-08-30 3:36 ` [PATCH v3 4/7] erofs: kill __packed for on-disk structures Gao Xiang
2019-08-30 6:16 ` Chao Yu
2019-08-30 3:36 ` [PATCH v3 5/7] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang
2019-08-30 6:17 ` Chao Yu
2019-08-30 3:36 ` [PATCH v3 6/7] erofs: remove all likely/unlikely annotations Gao Xiang
2019-08-30 6:25 ` Chao Yu
2019-08-30 6:31 ` Gao Xiang
2019-08-30 6:43 ` Chao Yu
2019-08-30 11:55 ` Dan Carpenter
2019-08-30 11:30 ` Dan Carpenter
2019-08-30 12:06 ` Gao Xiang
2019-08-30 15:46 ` Christoph Hellwig
2019-08-30 16:04 ` Gao Xiang
2019-08-31 10:57 ` Dan Carpenter
2019-08-30 3:36 ` [PATCH v3 7/7] erofs: redundant assignment in __erofs_get_meta_page() Gao Xiang
2019-08-30 6:25 ` Chao Yu
2019-08-30 16:28 ` Christoph Hellwig
2019-08-30 16:48 ` Gao Xiang
2019-08-30 15:25 ` [PATCH v3 1/7] erofs: on-disk format should have explicitly assigned numbers Gao Xiang
2019-08-30 15:45 ` [PATCH v2 2/7] erofs: some marcos are much more readable as a function Christoph Hellwig
2019-08-30 15:52 ` Gao Xiang [this message]
2019-08-30 15:56 ` Gao Xiang
2019-08-30 3:00 ` [PATCH v2 3/7] erofs: use a better form for complicated on-disk fields Gao Xiang
2019-08-30 3:29 ` Chao Yu
2019-08-30 3:00 ` [PATCH v2 4/7] erofs: kill __packed for on-disk structures Gao Xiang
2019-08-30 3:00 ` [PATCH v2 5/7] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang
2019-08-30 3:00 ` [PATCH v2 6/7] erofs: remove all likely/unlikely annotations Gao Xiang
2019-08-30 3:00 ` [PATCH v2 7/7] erofs: reduntant assignment in __erofs_get_meta_page() Gao Xiang
2019-08-30 3:28 ` [PATCH v2 1/7] erofs: on-disk format should have explicitly assigned numbers Chao Yu
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