Currently, ufs write support have two sets of problems: work with files and
work with directories.

This series of patches should solve the first problem.

This patch is similar to http://lkml.org/lkml/2006/1/17/61 this patch
complements it.

The situation the same: in ufs_trunc_(not direct), we read block, check if
count of links to it is equal to one, if so we finish cycle, if not
continue.  Because of "count of links" always >=2 this operation cause
infinite cycle and hang up the kernel.
Signed-off-by: NEvgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>