[PATCH] block: return specific error when pointer is NULL

[Qing Wang <wangqing@xxxxxxxx>]

From: Wang Qing <wangqing@xxxxxxxx>

loop_attr_backing_file_show() better return specific error than 0 
when pointer is NULL

Signed-off-by: Wang Qing <wangqing@xxxxxxxx>
---
 drivers/block/loop.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e52a8a5..860a5b6
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -667,7 +667,7 @@ static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
 	spin_unlock_irq(&lo->lo_lock);
 
 	if (IS_ERR_OR_NULL(p))
-		ret = PTR_ERR(p);
+		ret = p ? PTR_ERR(p) : -ENOENT;
 	else {
 		ret = strlen(p);
 		memmove(buf, p, ret);
-- 
2.7.4