[PATCH V2] mtd: improve calculating partition boundaries when checking for alignment

[Rafał Miłecki <zajec5@xxxxxxxxx>]

From: Rafał Miłecki <rafal@xxxxxxxxxx>

When checking for alignment mtd should check absolute offsets. It's
important for subpartitions as it doesn't make sense to check their
relative addresses.

Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
---
V2: Switch from uint64_t to u64. I got incorrectly inspired by
    uint64_t offset;
---
 drivers/mtd/mtdpart.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 2b6e53af47da..b6af41b04622 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -61,6 +61,15 @@ static inline struct mtd_part *mtd_to_part(const struct mtd_info *mtd)
 	return container_of(mtd, struct mtd_part, mtd);
 }
 
+static u64 part_absolute_offset(struct mtd_info *mtd)
+{
+	struct mtd_part *part = mtd_to_part(mtd);
+
+	if (!mtd_is_partition(mtd))
+		return 0;
+
+	return part_absolute_offset(part->parent) + part->offset;
+}
 
 /*
  * MTD methods which simply translate the effective address and pass through
@@ -514,7 +523,7 @@ static struct mtd_part *allocate_partition(struct mtd_info *parent,
 	if (!(slave->mtd.flags & MTD_NO_ERASE))
 		wr_alignment = slave->mtd.erasesize;
 
-	tmp = slave->offset;
+	tmp = part_absolute_offset(parent) + slave->offset;
 	remainder = do_div(tmp, wr_alignment);
 	if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
 		/* Doesn't start on a boundary of major erase size */
@@ -525,7 +534,7 @@ static struct mtd_part *allocate_partition(struct mtd_info *parent,
 			part->name);
 	}
 
-	tmp = slave->mtd.size;
+	tmp = part_absolute_offset(parent) + slave->mtd.size;
 	remainder = do_div(tmp, wr_alignment);
 	if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
 		slave->mtd.flags &= ~MTD_WRITEABLE;
-- 
2.13.7


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