mtdblock: tolerate corrected bit-flips

mtd_read() may return -EUCLEAN in case of corrected bit-flips.This
particular condition should not be treated like an error.
Signed-off-by: Bang Li <libang.linuxer@gmail.com>
Fixes: e47f6858 ("mtd: check for max_bitflips in mtd_read_oob()")
Cc: <stable@vger.kernel.org> # v3.7
Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230328163012.4264-1-libang.linuxer@gmail.com

drivers/mtd/mtdblock.c

@@ -153,7 +153,7 @@ static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
 				mtdblk->cache_state = STATE_EMPTY;
 				ret = mtd_read(mtd, sect_start, sect_size,
 					       &retlen, mtdblk->cache_data);
-				if (ret)
+				if (ret && !mtd_is_bitflip(ret))
 					return ret;
 				if (retlen != sect_size)
 					return -EIO;
@@ -188,8 +188,12 @@ static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
 	pr_debug("mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
 			mtd->name, pos, len);
 
-	if (!sect_size)
-		return mtd_read(mtd, pos, len, &retlen, buf);
+	if (!sect_size) {
+		ret = mtd_read(mtd, pos, len, &retlen, buf);
+		if (ret && !mtd_is_bitflip(ret))
+			return ret;
+		return 0;
+	}
 
 	while (len > 0) {
 		unsigned long sect_start = (pos/sect_size)*sect_size;
@@ -209,7 +213,7 @@ static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
 			memcpy (buf, mtdblk->cache_data + offset, size);
 		} else {
 			ret = mtd_read(mtd, pos, size, &retlen, buf);
-			if (ret)
+			if (ret && !mtd_is_bitflip(ret))
 				return ret;
 			if (retlen != size)
 				return -EIO;