[LSF/MM TOPIC] Parallelize file operation (like creation, unlink) under large shared directory

[wangdi <di.wang@whamcloud.com>]

Single directory performance is a critical in some use cases. For 
example the multiple application threads might create hundreds of 
thousands of files in a single directory simultaneously within a short 
window of time.

Currently, both filename lookup and file system modifying operations 
(such as create and unlink) are protected with a single lock for the 
entire directory. It might be useful to remove this lock, so multiple 
application threads can access the directory simultaneously.

Thanks
WangDi