[Linux-cluster] Re: GFS

[Zach Brown <zab zabbo net>]

Pekka J Enberg wrote:

> Sorry if this is an obvious question but what prevents another thread
> from doing mmap() before we do the second walk and messing up num_gh?

Nothing, I suspect.  OCFS2 has a problem like this, too.  It wants a way
for a file system to serialize mmap/munmap/mremap during file IO.  Well,
more specifically, it wants to make sure that the locks it acquired at
the start of the IO really cover the buf regions that might fault during
the IO.. mapping activity during the IO can wreck that.

- z