From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 16 Mar 2018 13:30:49 +0100 From: Greg Kroah-Hartman To: Christoph Biedl , linux-btrfs@vger.kernel.org Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Anand Jain , Liu Bo , David Sterba Subject: Re: [PATCH 4.14 024/110] btrfs: use proper endianness accessors for super_copy Message-ID: <20180316123049.GC25079@kroah.com> References: <20180307191039.748351103@linuxfoundation.org> <20180307191042.810088712@linuxfoundation.org> <1521139304@msgid.manchmal.in-ulm.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1521139304@msgid.manchmal.in-ulm.de> User-Agent: Mutt/1.9.4 (2018-02-28) X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, Mar 15, 2018 at 07:55:42PM +0100, Christoph Biedl wrote: > Greg Kroah-Hartman wrote... > > > 4.14-stable review patch. If anyone has any objections, please let me know. > > > commit 3c181c12c431fe33b669410d663beb9cceefcd1b upstream. > (...) > > > If the filesystem is always used on a same endian host, this will not > > be a problem. > > >From my observations I cannot quite subscribe to that. > > On big-endian systems, this change intruduces severe corruption, > resulting in complete loss of the data on the used block device. > > Steps to reproduce (tested on ppc/powerpc and parisc/hppa): > > # mkfs.btrfs $DEV > # mount $DEV /mnt/tmp/ > # umount /mnt/tmp/ > > This simple umount corrupts the file system: > > # mount $DEV /mnt/tmp/ > mount: /mnt/tmp: wrong fs type, bad option, bad superblock on $DEV, missing codepage or helper program, or other error. > > # dmesg: > BTRFS critical (device ): unable to find logical 4294967296 length 4096 > BTRFS critical (device ): unable to find logical 4294967296 length 4096 > BTRFS critical (device ): unable to find logical 18102363734671360 length 16384 > BTRFS error (device ): failed to read chunk root > BTRFS error (device ): open_ctree failed > > Also fsck is of no help: > > # btrfsck $DEV > Couldn't map the block 18102363734671360 > No mapping for 18102363734671360-18102363734687744 > Couldn't map the block 18102363734671360 > bytenr mismatch, want=18102363734671360, have=0 > ERROR: cannot read chunk root > ERROR: cannot open file system > > > Trying mount or fsck on a little-endian system does not help either. So > I consider the data on that device lost - luckily I use btrfs only for > files where a backup exists all the time. > > > Reverting that change restored the previous error-free behaviour. I > didn't check HEAD, i.e. v4.16-rc5, since the upstream commt was the last > that affected these files. Still I could give this a try if anybody > wishes so. That sucks. Can you test Linus's tree to verify the problem is there? I'll gladly revert this if Linus's tree also gets the revert, I don't want you to hit this when you upgrade to a newer kernel. thanks, greg k-h