UBI: avoid unnecessary division operations

UBI already checks that @min io size is the power of 2 at io_init.
It is save to use bit operations then.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 961416ac0616..ff4425de1527 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -530,7 +530,11 @@ static int io_init(struct ubi_device *ubi)
         ubi->min_io_size = ubi->mtd->writesize;
         ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft;
 
-        /* Make sure minimal I/O unit is power of 2 */
+        /*
+         * Make sure minimal I/O unit is power of 2. Note, there is no
+         * fundamental reason for this assumption. It is just an optimization
+         * which allows us to avoid costly division operations.
+         */
         if (!is_power_of_2(ubi->min_io_size)) {
                 ubi_err("min. I/O unit (%d) is not power of 2",
                         ubi->min_io_size);
@@ -581,7 +585,7 @@ static int io_init(struct ubi_device *ubi)
         if (ubi->vid_hdr_offset < UBI_EC_HDR_SIZE ||
             ubi->leb_start < ubi->vid_hdr_offset + UBI_VID_HDR_SIZE ||
             ubi->leb_start > ubi->peb_size - UBI_VID_HDR_SIZE ||
-            ubi->leb_start % ubi->min_io_size) {
+            ubi->leb_start & (ubi->min_io_size - 1)) {
                 ubi_err("bad VID header (%d) or data offsets (%d)",
                         ubi->vid_hdr_offset, ubi->leb_start);
                 return -EINVAL;