block: Fix overrun in lcm() and move it to lib
lcm() was defined to take integer-sized arguments. The supplied
arguments are multiplied, however, causing us to overflow given
sufficiently large input. That in turn led to incorrect optimal I/O
size reporting in some cases (RAID over RAID).
Switch lcm() over to unsigned long similar to gcd() and move the
function from blk-settings.c to lib.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/lib/Makefile b/lib/Makefile
index 2e152ae..0d40152 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -21,7 +21,7 @@
obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
- string_helpers.o gcd.o list_sort.o
+ string_helpers.o gcd.o lcm.o list_sort.o
ifeq ($(CONFIG_DEBUG_KOBJECT),y)
CFLAGS_kobject.o += -DDEBUG