fs/efs/super.c: fix return value

When sb_bread() fails, the return value should be -EIO, fix it.

Link: http://lkml.kernel.org/r/1463464943-4142-1-git-send-email-os@iscas.ac.cn
Signed-off-by: Heloise <os@iscas.ac.cn>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Firo Yang <firogm@gmail.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/efs/super.c

@@ -275,7 +275,7 @@ static int efs_fill_super(struct super_block *s, void *d, int silent)
 
 	if (!bh) {
 		pr_err("cannot read volume header\n");
-		return -EINVAL;
+		return -EIO;
 	}
 
 	/*
@@ -293,7 +293,7 @@ static int efs_fill_super(struct super_block *s, void *d, int silent)
 	bh = sb_bread(s, sb->fs_start + EFS_SUPER);
 	if (!bh) {
 		pr_err("cannot read superblock\n");
-		return -EINVAL;
+		return -EIO;
 	}
 		
 	if (efs_validate_super(sb, (struct efs_super *) bh->b_data)) {