On Thu, Mar 31 2022 at 5:15P -0400, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > On Wed, Mar 30, 2022 at 10:52:13PM -0700, Dennis Zhou wrote: > > I took a quick look. It seems with the new interface, > > bio_clone_blkg_association() is unnecessary given the correct > > association should be derived from the bio_alloc*() calls with the > > passed in bdev. Also, blkcg_bio_issue_init() in clone seems wrong. > > Yes, I think you are right. > > > Maybe the right thing to do here for md-linear and btrfs (what I've > > looked at) is to delay cloning until the map occurs and the right device > > is already in hand? > > That would in general be the preferred option where possible. Delaying cloning until remap is a problem for DM given the target_type ->map interface for all DM targets assumes the passed bio is already a clone that needs to be remapped accordingly. I think we can achieve the goal of efficient cloning/remapping for both usecases simply by splitting out the bio_set_dev() and leaving it to the caller to pick which interface to use (e.g. clone vs clone_and_remap). Christoph is this something you're open to doing as continuation of your bio alloc/clone related audit/changes? Or would you prefer someone else deal with it? I could take a closer look next week if needed. Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
