On Wed, Sep 11 2019, Song Liu wrote: > On Wed, Sep 11, 2019 at 12:10 AM NeilBrown <[email protected]> wrote: >> >> On Tue, Sep 10 2019, Guoqing Jiang wrote: >> >> > On 9/10/19 5:45 PM, Song Liu wrote: >> >> >> >> >> >>> On Sep 10, 2019, at 12:33 AM, NeilBrown <[email protected]> wrote: >> >>> >> >>> On Mon, Sep 09 2019, Song Liu wrote: >> >>> >> >>>> Hi Neil, >> >>>> >> >>>>> On Sep 9, 2019, at 7:57 AM, NeilBrown <[email protected]> wrote: >> >>>>> >> >>>>> >> >>>>> If the drives in a RAID0 are not all the same size, the array is >> >>>>> divided into zones. >> >>>>> The first zone covers all drives, to the size of the smallest. >> >>>>> The second zone covers all drives larger than the smallest, up to >> >>>>> the size of the second smallest - etc. >> >>>>> >> >>>>> A change in Linux 3.14 unintentionally changed the layout for the >> >>>>> second and subsequent zones. All the correct data is still stored, but >> >>>>> each chunk may be assigned to a different device than in pre-3.14 >> >>>>> kernels. >> >>>>> This can lead to data corruption. >> >>>>> >> >>>>> It is not possible to determine what layout to use - it depends which >> >>>>> kernel the data was written by. >> >>>>> So we add a module parameter to allow the old (0) or new (1) layout to >> >>>>> be >> >>>>> specified, and refused to assemble an affected array if that parameter >> >>>>> is >> >>>>> not set. >> >>>>> >> >>>>> Fixes: 20d0189b1012 ("block: Introduce new bio_split()") >> >>>>> cc: [email protected] (3.14+) >> >>>>> Signed-off-by: NeilBrown <[email protected]> >> >>>> >> >>>> Thanks for the patches. They look great. However, I am having problem >> >>>> apply them (not sure whether it is a problem on my side). Could you >> >>>> please push it somewhere so I can use cherry-pick instead? >> >>> >> >>> I rebased them on block/for-next, fixed the problems that Guoqing found, >> >>> and pushed them to >> >>> https://github.com/neilbrown/linux md/raid0 >> >>> >> >>> NeilBrown >> >> >> >> Thanks Neil! >> > >> > Thanks for the explanation about set the flag. >> > >> >> >> >> Guoqing, if this looks good, please reply with your Reviewed-by >> >> or Acked-by. >> > >> > No more comments from my side, but I am not sure if it is better/possible >> > to use one >> > sysfs node to control the behavior instead of module parameter, then we >> > can support >> > different raid0 layout dynamically. >> >> A strength of module parameters is that you can set them in >> /etc/modprobe.d/00-local.conf >> and then they are automatically set on boot. >> For sysfs, you need some tool to set them. >> >> > >> > Anyway, Acked-by: Guoqing Jiang <[email protected]> >> > > > I am adding the following change to the 1/2. Please let me know if it doesn't > make sense.
I don't object, through with the current code it is impossible for that
warning to fire.
Code might change in the future though, and it's better to be safe than
sorry.
Thanks,
NeilBrown
>
> Thanks,
> Song
>
> diff --git i/drivers/md/raid0.c w/drivers/md/raid0.c
> index a9fcff50bbfc..54d0064787a8 100644
> --- i/drivers/md/raid0.c
> +++ w/drivers/md/raid0.c
> @@ -615,6 +615,10 @@ static bool raid0_make_request(struct mddev
> *mddev, struct bio *bio)
> case RAID0_ALT_MULTIZONE_LAYOUT:
> tmp_dev = map_sector(mddev, zone, sector, §or);
> break;
> + default:
> + WARN("md/raid0:%s: Invalid layout\n", mdname(mddev));
> + bio_io_error(bio);
> + return true;
> }
>
> if (unlikely(is_mddev_broken(tmp_dev, "raid0"))) {
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