While UBI and UBIFS seem to work at first sight with MLC NAND, you will
most likely lose all your data upon a power-cut or due to read/write
disturb.
In order to protect users from bad surprises, refuse to attach to MLC
NAND.

Cc: sta...@vger.kernel.org
Signed-off-by: Richard Weinberger <rich...@nod.at>
---
 drivers/mtd/ubi/build.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index e941395de3ae..753494e042d5 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -854,6 +854,17 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
                return -EINVAL;
        }
 
+       /*
+        * Both UBI and UBIFS have been designed for SLC NAND and NOR flashes.
+        * MLC NAND is different and needs special care, otherwise UBI or UBIFS
+        * will die soon and you will lose all your data.
+        */
+       if (mtd->type == MTD_MLCNANDFLASH) {
+               pr_err("ubi: refuse attaching mtd%d - MLC NAND is not 
supported\n",
+                       mtd->index);
+               return -EINVAL;
+       }
+
        if (ubi_num == UBI_DEV_NUM_AUTO) {
                /* Search for an empty slot in the @ubi_devices array */
                for (ubi_num = 0; ubi_num < UBI_MAX_DEVICES; ubi_num++)
-- 
2.13.6

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