snprintf() will return the 'ideal' length which may be larger than real
buffer length, if we only want to use real length, need use scnprintf()
instead of.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>