On 2/11/19 8:18 PM, bugfood-ml@xxxxxxxxxx wrote:
> From: Corey Hickey <bugfood-c@xxxxxxxxxx>
>
> ...when not changing the number of disks.
>
> This patch needs context to explain. These are the relevant parts of
> the original code (condensed and annotated):
>
> if (dir > 0) {
> /* Increase data offset (reshape backwards) */
> if (data_offset < sd->data_offset + min) {
> pr_err("--data-offset too small on %s\n",
> dn);
> goto release;
> }
> } else {
> /* Decrease data offset (reshape forwards) */
> if (data_offset < sd->data_offset - min) {
> pr_err("--data-offset too small on %s\n",
> dn);
> goto release;
> }
> }
>
> When this code is reached, mdadm has already decided on a reshape
> direction. When increasing the data offset, the reshape runs backwards
> (dir==1); when decreasing the data offset, the reshape runs forwards
> (dir==-1).
>
> The conditional within the backwards reshape is correct: the requested
> offset must be larger than the old offset plus a minimum delta; thus the
> reshape has room to work.
>
> For the forwards reshape, the requested offset needs to be smaller than
> the old offset minus a minimum delta; to do this correctly, the
> comparison must be reversed.
>
> Also update the error message.
>
> Note: I have tested this change on a RAID 5 on Linux 4.18.0 and verified
> that there were no errors from the kernel and that the device data
> remained intact. I do not know if there are considerations for different
> RAID levels.
>
> Signed-off-by: Corey Hickey <bugfood-c@xxxxxxxxxx>
> ---
> Grow.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
Applied!
Thanks,
Jes
