bcachefs: fs-ioctl: Fix copy_to_user() error code

The copy_to_user() function returns the number of bytes that it wasn't
able to copy but we want to return -EFAULT to the user.

Fixes: e0750d947352 ("bcachefs: Initial commit")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/fs-ioctl.c

@@ -122,7 +122,10 @@ static int bch2_ioc_fsgetxattr(struct bch_inode_info *inode,
 
 	fa.fsx_projid = inode->ei_qid.q[QTYP_PRJ];
 
-	return copy_to_user(arg, &fa, sizeof(fa));
+	if (copy_to_user(arg, &fa, sizeof(fa)))
+		return -EFAULT;
+
+	return 0;
 }
 
 static int fssetxattr_inode_update_fn(struct btree_trans *trans,