On Tue, Apr 09, 2013 at 04:32:28PM -0400, Mikulas Patocka wrote: [..] > Generally, we shouldn't associate bios with "current" task in device > mapper targets. For example suppose that we have two stacked dm-crypt > targets: > > In the "current" process pointer in lower dm-crypt target's request > function always points to the workqueue of the upper dm-crypt target that > submits the bios. So if we associate the bio with "current" in the lower > target, we are associating it with a preallocated workqueue and we already > lost the information who submitted it. > > You should associate a bio with a task when you create the bio and "md" > and "dm" midlayers should just forward this association to lower layer > bios. bio_associate_current() return -EBUSY if bio has already been associated with an io context. So in a stack if every driver calls bio_associate_current(), upon bio submission, it will automatically amke sure bio gets associated with submitter task in top level device and calls by lower level device will be ignored. Lower level devices I think just need to make sure this context info is propogated to cloned bios. [..] > +#ifdef CONFIG_BLK_CGROUP > + tio->clone.bi_ioc = ci->bio->bi_ioc; > + tio->clone.bi_css = ci->bio->bi_css; You also need to take references to ioc and css objects. I guess a helper function will be better. May be something like. bio_associate_bio_context(bio1, bio2) And this initialize bio2's context with bio1's context. Thanks Vivek -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
