Use unsigned instead of int for the parameter which carries a blocksize.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NWei Yongjun <yjwei@cn.fujitsu.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>