From: Tiezhu Yang <yangtiezhu@loongson.cn>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: ecryptfs@vger.kernel.org, "Theodore Y. Ts'o" <tytso@mit.edu>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
linux-kernel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
Tyler Hicks <tyhicks@canonical.com>,
Eric Biggers <ebiggers@kernel.org>,
linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Jaegeuk Kim <jaegeuk@kernel.org>,
linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH v5] fs: introduce is_dot_or_dotdot helper for cleanup
Date: Wed, 11 Dec 2019 14:38:34 +0800 [thread overview]
Message-ID: <4a90aaa9-18c8-f0a7-19e4-1c5bd5915a28@loongson.cn> (raw)
In-Reply-To: <20191211044723.GC4203@ZenIV.linux.org.uk>
On 12/11/2019 12:47 PM, Al Viro wrote:
> On Wed, Dec 11, 2019 at 11:59:40AM +0800, Tiezhu Yang wrote:
>
>> static inline bool is_dot_or_dotdot(const unsigned char *name, size_t len)
>> {
>> if (len == 1 && name[0] == '.')
>> return true;
>>
>> if (len == 2 && name[0] == '.' && name[1] == '.')
>> return true;
>>
>> return false;
>> }
>>
>> Hi Matthew,
>>
>> How do you think? I think the performance influence is very small
>> due to is_dot_or_dotdot() is a such short static inline function.
> It's a very short inline function called on a very hot codepath.
> Often.
>
> I mean it - it's done literally for every pathname component of
> every pathname passed to a syscall.
OK. I understand. Let us do not use the helper function in fs/namei.c,
just use the following implementation for other callers:
static inline bool is_dot_or_dotdot(const unsigned char *name, size_t len)
{
if (len >= 1 && unlikely(name[0] == '.')) {
if (len < 2 || (len == 2 && name[1] == '.'))
return true;
}
return false;
}
Special thanks for Matthew, Darrick, Al and Eric.
If you have any more suggestion, please let me know.
Thanks,
Tiezhu Yang
next prev parent reply other threads:[~2019-12-11 6:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-11 2:20 [PATCH v5] fs: introduce is_dot_or_dotdot helper for cleanup Tiezhu Yang
2019-12-11 2:48 ` Eric Biggers
2019-12-11 3:59 ` Tiezhu Yang
2019-12-11 4:47 ` Al Viro
2019-12-11 6:38 ` Tiezhu Yang [this message]
2019-12-11 7:17 ` Gao Xiang
2019-12-11 13:40 ` Matthew Wilcox
2019-12-11 14:41 ` Gao Xiang
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