From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-f171.google.com ([209.85.208.171]:36277 "EHLO mail-lj1-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733019AbeHAHQh (ORCPT ); Wed, 1 Aug 2018 03:16:37 -0400 Received: by mail-lj1-f171.google.com with SMTP id u7-v6so15775955lji.3 for ; Tue, 31 Jul 2018 22:32:48 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Chris Murphy Date: Tue, 31 Jul 2018 23:32:46 -0600 Message-ID: Subject: Re: Unmountable root partition To: Cerem Cem ASLAN Cc: Btrfs BTRFS Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Jul 31, 2018 at 12:03 PM, Cerem Cem ASLAN wrote: > 3. mount -t btrfs /dev/mapper/foo--vg-root /mnt/foo > Gives the following error: > > mount: wrong fs type, bad option, bad superblock on ... > > 4. dmesg | tail > Outputs the following: > > > [17755.840916] sd 3:0:0:0: [sda] tag#0 FAILED Result: > hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK > [17755.840919] sd 3:0:0:0: [sda] tag#0 CDB: Read(10) 28 00 00 07 c0 02 00 00 > 02 00 > [17755.840921] blk_update_request: I/O error, dev sda, sector 507906 > [17755.840941] EXT4-fs (dm-4): unable to read superblock Are you sure this is the output for the command? Because you're explicitly asking for type btrfs, which fails, and then the kernel reports EXT4 superblock unreadable. What do you get if you omit -t btrfs and just let it autodetect? But yeah, this is an IO error from the device and there's nothing Btrfs can do about that unless there is DUP or raid1+ metadata available. Is it possible this LV was accidentally reformatted ext4? -- Chris Murphy