On Mon, Feb 19, 2024 at 04:53:36PM +0800, Yu Kuai wrote: > Can you take a look at this patch? I think for raid(perhaps and dm and > other drivers), it's reasonable to suspend IO while hot adding new > underlying disks. And I think add new slaves to holder is not related to > open the holder disk, because caller should already open the holder disk > to hot add slaves, hence 'open_mutex' for holder is not necessary here. > > Actually bd_link_disk_holder() is protected by 'reconfig_mutex' for > raid, and 'table_devices_lock' for dm(I'm not sure yet if other drivers > have similiar lock). > > For raid, we do can fix this problem in raid by delay > bd_link_disk_holder() while the array is not suspended, however, we'll > consider this fix later if you think this patch is not acceptable. Yes, not taking open_lock here seems reasonable, open_lock or it's previous name has always been a bit of a catchall without very well defined semantics. I'd give the symbol a blk_ prefix, though.
