On 1/7/25 12:24 PM, Mike Snitzer wrote:
On Thu, Jan 02, 2025 at 07:28:41PM +0800, Yu Kuai wrote:From: Yu Kuai <yukuai3@xxxxxxxxxx> THe md-linear is removed by commit 849d18e27be9 ("md: Remove deprecated CONFIG_MD_LINEAR") because it has been marked as deprecated for a long time. However, md-linear is used widely for underlying disks with different size, sadly we didn't know this until now, and it's true useful to create partitions and assemble multiple raid and then append one to the other. People have to use dm-linear in this case now, however, they will prefer to minimize the number of involved modules. Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>I agree with reinstating md-linear. If/when we do remove md-linear (again) we first need a seamless upgrade/conversion option (e.g. mdadm updated to use dm-linear in the backend instead of md-linear).
Agree with the need for an upgrade/conversion path.
This patch's header should probably also have this Fixes tag (unclear if linux-stable would pick it up but it really is a regression given there was no upgrade path offered to md-linear users): Fixes: 849d18e27be9 md: Remove deprecated CONFIG_MD_LINEAR Acked-by: Mike Snitzer <snitzer@xxxxxxxxxx>
