On 02/22/2018 02:00 AM, bingjingc wrote:
> From: BingJing Chang <bingjingc@xxxxxxxxxxxx>
>
> With "--force", we can assemble the array even if some superblocks
> appear out-of-date. But their data layout is regarded to make sense.
> In reshape cases, if two devices claims different reshape progresses,
> we cannot forcely assemble them back to array. Kernel will treat only
> one of them as reshape progress. However, their data is still laid on
> different layouts. It may lead to disaster if reshape goes on.
>
> Reproducible Steps:
> mdadm -C /dev/md0 --assume-clean -l5 -n3 /dev/loop[012]
> mdadm -a /dev/md0 /dev/loop3
> mdadm -G /dev/md0 -n4
> mdadm -f /dev/md0 /dev/loop0 # after a period
> mdadm -S /dev/md0 # after another period
> mdadm -E /dev/loop[01] # make sure that they claims different ones
>
> mdadm -Af -R /dev/md0 /dev/loop[023] # give no enough devices for
> force_array() to pick non-fresh devices
> cat /sys/block/md0/md/reshape_position # You can see that Kernel resume
> reshape the from any progress of them.
>
> Note: The unit of mdadm -E is KB, but reshape_position's is sector.
>
> In order to prevent disaster, we add logics to prevent devices with
> different reshape progress from being added into the array.
>
> Reported-by: Allen Peng <allenpeng@xxxxxxxxxxxx>
> Reviewed-by: Alex Wu <alexwu@xxxxxxxxxxxx>
> Signed-off-by: BingJing Chang <bingjingc@xxxxxxxxxxxx>
> ---
> Assemble.c | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
Applied!
Thanks,
Jes
> diff --git a/Assemble.c b/Assemble.c
> index 9e19246..9f33c61 100644
> --- a/Assemble.c
> +++ b/Assemble.c
> @@ -846,7 +846,19 @@ static int force_array(struct mdinfo *content,
> /* OK */;
> else
> continue;
> - }
> + } else if (devices[j].i.reshape_active !=
> + content->reshape_active ||
> + (devices[j].i.reshape_active &&
> + devices[j].i.reshape_progress !=
> + content->reshape_progress))
> + /* Here, it may be a source of data. If two
> + * devices claim different progresses, it
> + * means that reshape boundaries differ for
> + * their own devices. Kernel will only treat
> + * the first one as reshape progress and
> + * go on. It may cause disaster, so avoid it.
> + */
> + continue;
> if (chosen_drive < 0 ||
> devices[j].i.events
> > devices[chosen_drive].i.events)
> @@ -908,7 +920,13 @@ static int force_array(struct mdinfo *content,
> if (j >= 0 &&
> !devices[j].uptodate &&
> devices[j].i.recovery_start == MaxSector &&
> - devices[j].i.events == current_events) {
> + devices[j].i.events == current_events &&
> + ((!devices[j].i.reshape_active &&
> + !content->reshape_active) ||
> + (devices[j].i.reshape_active ==
> + content->reshape_active &&
> + devices[j].i.reshape_progress ==
> + content->reshape_progress))) {
> chosen_drive = j;
> goto add_another;
> }
>
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