Pull sendfile updates from Al Viro:
"Make sendfile() to pipe destination do the right thing, should make
'fs/pipe: allow sendfile() to pipe again' redundant"
* 'work.sendfile' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
teach sendfile(2) to handle send-to-pipe directly
take the guts of file-to-pipe splice into a helper function
do_splice_to(): move the logics for limiting the read length in