Revert "ext4: consolidate checks for resize of bigalloc into ext4_resize_begin"

The function ext4_resize_begin() gets called from three different
places, and online resize for bigalloc file systems is disallowed from
the old-style online resize (EXT4_IOC_GROUP_ADD and
EXT4_IOC_GROUP_EXTEND), but it *is* supposed to be allowed via
EXT4_IOC_RESIZE_FS.

This reverts commit e9f9f61.

Author: tytso

fs/ext4/ioctl.c

@@ -692,6 +692,13 @@ static long ext4_ioctl_group_add(struct file *file,
 	if (err)
 		return err;
 
+	if (ext4_has_feature_bigalloc(sb)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online resizing not supported with bigalloc");
+		err = -EOPNOTSUPP;
+		goto group_add_out;
+	}
+
 	err = mnt_want_write_file(file);
 	if (err)
 		goto group_add_out;
@@ -914,6 +921,13 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 			goto group_extend_out;
 		}
 
+		if (ext4_has_feature_bigalloc(sb)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Online resizing not supported with bigalloc");
+			err = -EOPNOTSUPP;
+			goto group_extend_out;
+		}
+
 		err = mnt_want_write_file(filp);
 		if (err)
 			goto group_extend_out;

fs/ext4/resize.c

@@ -74,10 +74,6 @@ int ext4_resize_begin(struct super_block *sb)
 		return -EPERM;
 	}
 
-	if (ext4_has_feature_bigalloc(sb)) {
-		ext4_msg(sb, KERN_ERR, "Online resizing not supported with bigalloc");
-		return -EOPNOTSUPP;
-	}
 	if (ext4_has_feature_sparse_super2(sb)) {
 		ext4_msg(sb, KERN_ERR, "Online resizing not supported with sparse_super2");
 		return -EOPNOTSUPP;