From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 323C4128395 for ; Tue, 10 Feb 2026 02:00:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770688841; cv=none; b=XyM2K+HoyjBwiYeuIG9AYqeYHqXMOXbPRrDn/OZZ5YgWoOtC8myLO5FIyf1Yk/w5Xs0JT0KE+x9RfvTj+Cf1ghS8FRPYn8ekdiLgTRW3PAgHYmMe7qYxLaY6/fyrD/X6wBtfGnreqwcp0f2CL4vZzIRgrepZLDbIgi7k7MpAVyc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770688841; c=relaxed/simple; bh=KVPReESYyKCiXNwAWln9qboAf73skfa/b6cY3Th6vAU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=N5Ma1UUsfGJnGzJPLwDVm1MkJZyshn6KabAbDzi337Efe0gV7dKtsveDKq0uhWB3BFZsTSYLUCTUUhYGaz81NyfLTx2zDu92vxUV/aEORKA3t1QpY+w8vaITnEiCRGjxsCJSGFUpgxoOgYa4TtY94p5hc4fQT+E0558YVJQMq34= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tH2n6kkC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tH2n6kkC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B48C7C116C6; Tue, 10 Feb 2026 02:00:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770688840; bh=KVPReESYyKCiXNwAWln9qboAf73skfa/b6cY3Th6vAU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tH2n6kkCmhThvpDJyAdbdAhXLlKlIDJpIwpRR1+7+SDPEct4ZUlN60tP1Nl/ZNsPN jDrZUvVA2eWY8OJJKGav0Mo6LQcTcjXwtdjAv/ygseYblvFKlOcxdNNmi3YXtEpG1h ukN9mxVoJ3/oCHt+ROsHsxsakeAw+vcpP42FKToJmHaDMSptqesXmka3ef9DaWGr4O MXx9pMLA3MgpD6eXXQoLIGMrirEacsydXXSVJdL9lU8TGwgkB8pdLiY0NxgDp3Jm2T yiCUmDOjW90zgp6nUGPL8BSEZSbgrCNmuslUNAXo9IF9l2g05fQT3bjAZyxjo5XPP7 5yaJkwT69bWbA== Date: Mon, 9 Feb 2026 18:00:40 -0800 From: "Darrick J. Wong" To: Shinichiro Kawasaki Cc: hch , "linux-xfs@vger.kernel.org" Subject: Re: [bug report] xfs/802 failure due to mssing fstype report by lsblk Message-ID: <20260210020040.GC7712@frogsfrogsfrogs> References: <20260206173805.GY7712@frogsfrogsfrogs> <20260209060716.GL1535390@frogsfrogsfrogs> <20260209062821.GA9021@lst.de> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Feb 09, 2026 at 07:54:38AM +0000, Shinichiro Kawasaki wrote: > On Feb 09, 2026 / 07:28, hch wrote: > > On Sun, Feb 08, 2026 at 10:07:16PM -0800, Darrick J. Wong wrote: > > > Waitaminute, how can you even format xfs on nullblk to run fstests? > > > Isn't that the bdev that silently discards everything written to it, and > > > returns zero on reads?? > > > > nullblk can be used with or without a backing store. In the former > > case it will not always return zeroes on reads obviously. > > Yes, null_blk has the "memory_backed" parameter. When 1 is set to this, data > written to the null_blk device is kept and read back. I create two 8GiB null_blk > devices enabling this memory_backed option, and use them as TEST_DEV and > SCRATCH_DEV for the regular xfs test runs. Huh, ok. Just out of curiosity, does blkid (in cache mode) /ever/ see the xfs filesystem? I'm wondering if there's a race, a slow utility, or if whatever builds the blkid cache sees that it's nullblk and ignores it? --D