Messages in this thread | | | Subject | Re: [PATCH 4.14 024/110] btrfs: use proper endianness accessors for super_copy | From | Anand Jain <> | Date | Sat, 17 Mar 2018 00:21:57 +0800 |
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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 >
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