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.