--- zzzz-none-000/linux-3.10.107/drivers/mtd/ubi/kapi.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/mtd/ubi/kapi.c	2021-02-04 17:41:59.000000000 +0000
@@ -137,7 +137,7 @@
 		return ERR_PTR(-EINVAL);
 
 	if (mode != UBI_READONLY && mode != UBI_READWRITE &&
-	    mode != UBI_EXCLUSIVE)
+	    mode != UBI_EXCLUSIVE && mode != UBI_METAONLY)
 		return ERR_PTR(-EINVAL);
 
 	/*
@@ -182,10 +182,17 @@
 		break;
 
 	case UBI_EXCLUSIVE:
-		if (vol->exclusive || vol->writers || vol->readers)
+		if (vol->exclusive || vol->writers || vol->readers ||
+		    vol->metaonly)
 			goto out_unlock;
 		vol->exclusive = 1;
 		break;
+
+	case UBI_METAONLY:
+		if (vol->metaonly || vol->exclusive)
+			goto out_unlock;
+		vol->metaonly = 1;
+		break;
 	}
 	get_device(&vol->dev);
 	vol->ref_count += 1;
@@ -204,7 +211,7 @@
 			return ERR_PTR(err);
 		}
 		if (err == 1) {
-			ubi_warn("volume %d on UBI device %d is corrupted",
+			ubi_warn(ubi, "volume %d on UBI device %d is corrupted",
 				 vol_id, ubi->ubi_num);
 			vol->corrupted = 1;
 		}
@@ -221,7 +228,7 @@
 	kfree(desc);
 out_put_ubi:
 	ubi_put_device(ubi);
-	ubi_err("cannot open device %d, volume %d, error %d",
+	ubi_err(ubi, "cannot open device %d, volume %d, error %d",
 		ubi_num, vol_id, err);
 	return ERR_PTR(err);
 }
@@ -307,7 +314,7 @@
 	if (error)
 		return ERR_PTR(error);
 
-	inode = path.dentry->d_inode;
+	inode = d_backing_inode(path.dentry);
 	mod = inode->i_mode;
 	ubi_num = ubi_major2num(imajor(inode));
 	vol_id = iminor(inode) - 1;
@@ -343,6 +350,10 @@
 		break;
 	case UBI_EXCLUSIVE:
 		vol->exclusive = 0;
+		break;
+	case UBI_METAONLY:
+		vol->metaonly = 0;
+		break;
 	}
 	vol->ref_count -= 1;
 	spin_unlock(&ubi->volumes_lock);
@@ -355,6 +366,43 @@
 EXPORT_SYMBOL_GPL(ubi_close_volume);
 
 /**
+ * leb_read_sanity_check - does sanity checks on read requests.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ *
+ * This function is used by ubi_leb_read() and ubi_leb_read_sg()
+ * to perform sanity checks.
+ */
+static int leb_read_sanity_check(struct ubi_volume_desc *desc, int lnum,
+				 int offset, int len)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int vol_id = vol->vol_id;
+
+	if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
+	    lnum >= vol->used_ebs || offset < 0 || len < 0 ||
+	    offset + len > vol->usable_leb_size)
+		return -EINVAL;
+
+	if (vol->vol_type == UBI_STATIC_VOLUME) {
+		if (vol->used_ebs == 0)
+			/* Empty static UBI volume */
+			return 0;
+		if (lnum == vol->used_ebs - 1 &&
+		    offset + len > vol->last_eb_bytes)
+			return -EINVAL;
+	}
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	return 0;
+}
+
+/**
  * ubi_leb_read - read data.
  * @desc: volume descriptor
  * @lnum: logical eraseblock number to read from
@@ -390,28 +438,16 @@
 
 	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
 
-	if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
-	    lnum >= vol->used_ebs || offset < 0 || len < 0 ||
-	    offset + len > vol->usable_leb_size)
-		return -EINVAL;
-
-	if (vol->vol_type == UBI_STATIC_VOLUME) {
-		if (vol->used_ebs == 0)
-			/* Empty static UBI volume */
-			return 0;
-		if (lnum == vol->used_ebs - 1 &&
-		    offset + len > vol->last_eb_bytes)
-			return -EINVAL;
-	}
+	err = leb_read_sanity_check(desc, lnum, offset, len);
+	if (err < 0)
+		return err;
 
-	if (vol->upd_marker)
-		return -EBADF;
 	if (len == 0)
 		return 0;
 
 	err = ubi_eba_read_leb(ubi, vol, lnum, buf, offset, len, check);
 	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {
-		ubi_warn("mark volume %d as corrupted", vol_id);
+		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);
 		vol->corrupted = 1;
 	}
 
@@ -419,6 +455,46 @@
 }
 EXPORT_SYMBOL_GPL(ubi_leb_read);
 
+
+/**
+ * ubi_leb_read_sg - read data into a scatter gather list.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @buf: buffer where to store the read data
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ * @check: whether UBI has to check the read data's CRC or not.
+ *
+ * This function works exactly like ubi_leb_read_sg(). But instead of
+ * storing the read data into a buffer it writes to an UBI scatter gather
+ * list.
+ */
+int ubi_leb_read_sg(struct ubi_volume_desc *desc, int lnum, struct ubi_sgl *sgl,
+		    int offset, int len, int check)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int err, vol_id = vol->vol_id;
+
+	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
+
+	err = leb_read_sanity_check(desc, lnum, offset, len);
+	if (err < 0)
+		return err;
+
+	if (len == 0)
+		return 0;
+
+	err = ubi_eba_read_leb_sg(ubi, vol, sgl, lnum, offset, len, check);
+	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {
+		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);
+		vol->corrupted = 1;
+	}
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(ubi_leb_read_sg);
+
 /**
  * ubi_leb_write - write data.
  * @desc: volume descriptor