[PATCH] fs/inode.c: make iprune_mutex static

There's no reason for iprune_mutex being global.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>