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authorMartin K. Petersen <martin.petersen@oracle.com>2010-03-15 07:46:51 -0400
committerJens Axboe <jens.axboe@oracle.com>2010-03-15 07:47:59 -0400
commit2cda2728aa1c8c006418a24f867b25e5eb7a32e2 (patch)
treec23ec7c38d74237646c5453d96bfbbea4cadfee7 /lib/lcm.c
parentf11c9c5c259cb2c3d698548dc3936f773ab1f5b9 (diff)
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>
Diffstat (limited to 'lib/lcm.c')
-rw-r--r--lib/lcm.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/lib/lcm.c b/lib/lcm.c
new file mode 100644
index 000000000000..157cd88a6ffc
--- /dev/null
+++ b/lib/lcm.c
@@ -0,0 +1,15 @@
1#include <linux/kernel.h>
2#include <linux/gcd.h>
3#include <linux/module.h>
4
5/* Lowest common multiple */
6unsigned long lcm(unsigned long a, unsigned long b)
7{
8 if (a && b)
9 return (a * b) / gcd(a, b);
10 else if (b)
11 return b;
12
13 return a;
14}
15EXPORT_SYMBOL_GPL(lcm);