UBI: avoid unnecessary division operations

[pandora-kernel.git] / drivers / mtd / ubi / build.c

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 961416a..ff4425d 100644 (file)
--- 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;