Modify pipe_write to first call sb_start_write_try() and upon encountering a frozen fs, skip the time update. Gentoo Kernel bug #493002. Thanks to the author, Dmitry Monakhov  <dmonakhov@openvz.org>

git-svn-id: svn://anonsvn.gentoo.org/linux-patches@2611 00c4350b-4cf9-0310-8c1b-f3fed11d2be3