mtd: Introduce mtd_block_isreserved()

In addition to mtd_block_isbad(), which checks if a block is bad or
reserved, it's needed to check if a block is reserved only (but not
bad). This commit adds an MTD interface for it, in a similar fashion to
mtd_block_isbad().

While here, fix mtd_block_isbad() so the out-of-bounds checking is done
before the callback check.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: Pekon Gupta <pekon@ti.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 11857fa..e4831b4 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -1043,12 +1043,22 @@
 }
 EXPORT_SYMBOL_GPL(mtd_is_locked);
 
-int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs)
+int mtd_block_isreserved(struct mtd_info *mtd, loff_t ofs)
 {
-	if (!mtd->_block_isbad)
-		return 0;
 	if (ofs < 0 || ofs > mtd->size)
 		return -EINVAL;
+	if (!mtd->_block_isreserved)
+		return 0;
+	return mtd->_block_isreserved(mtd, ofs);
+}
+EXPORT_SYMBOL_GPL(mtd_block_isreserved);
+
+int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs)
+{
+	if (ofs < 0 || ofs > mtd->size)
+		return -EINVAL;
+	if (!mtd->_block_isbad)
+		return 0;
 	return mtd->_block_isbad(mtd, ofs);
 }
 EXPORT_SYMBOL_GPL(mtd_block_isbad);