lkml.org 
[lkml]   [2018]   [Mar]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 4.14 024/110] btrfs: use proper endianness accessors for super_copy
    From
    Date


    On 03/16/2018 10:02 PM, Greg Kroah-Hartman wrote:
    > On Fri, Mar 16, 2018 at 02:22:02PM +0100, David Sterba wrote:
    >> On Fri, Mar 16, 2018 at 01:30:49PM +0100, Greg Kroah-Hartman wrote:
    >>> 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 <dev>): unable to find logical 4294967296 length 4096
    >>>> BTRFS critical (device <dev>): unable to find logical 4294967296 length 4096
    >>>> BTRFS critical (device <dev>): unable to find logical 18102363734671360 length 16384
    >>>> BTRFS error (device <dev>): failed to read chunk root
    >>>> BTRFS error (device <dev>): 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.
    >>
    >> I'll push a fix for the upcoming rc but I think it would be better to
    >> remove the broken patch from stable kernels ASAP, so I'd recommend to
    >> revert it now.
    >
    > Now reverted, thanks.

    Thanks ! Sorry for the mess.

    -Anand

    > greg k-h
    > --
    > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at http://vger.kernel.org/majordomo-info.html
    >

    \
     
     \ /
      Last update: 2018-03-16 17:21    [W:5.289 / U:0.032 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site