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
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