---- a/drivers/mtd/mtdpart.c
-+++ b/drivers/mtd/mtdpart.c
-@@ -332,7 +332,14 @@ static int part_lock(struct mtd_info *mt
- static int part_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
- {
- struct mtd_part *part = PART(mtd);
-- return part->master->_unlock(part->master, ofs + part->offset, len);
-+
-+ ofs += part->offset;
-+ if (mtd->flags & MTD_ERASE_PARTIAL) {
-+ /* round up len to next erasesize and round down offset to prev block */
-+ len = (mtd_div_by_eb(len, part->master) + 1) * part->master->erasesize;
-+ ofs &= ~(part->master->erasesize - 1);
-+ }
-+ return part->master->_unlock(part->master, ofs, len);
- }
-
- static int part_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)