On Wed, Oct 12, 2011 at 05:22:41PM -0400, Jeff Moyer wrote: > A dm-multipath user reported[1] a problem when trying to boot > a kernel with commit 4853abaae7e4a2af938115ce9071ef8684fb7af4 > (block: fix flush machinery for stacking drivers with differring > flush flags) applied. It turns out that an empty flush request > can be sent into blk_insert_flush. When the BUG_ON was fixed > to allow for this, I/O on the underlying device would stall. The > reason is that blk_insert_cloned_request does not kick the queue. > In the aforementioned commit, I had added a special case to > kick the queue if data was sent down but the queue flags did > not require a flush. A better solution is to push the queue > kick up into blk_insert_cloned_request. > > This patch, along with a follow-on which fixes the BUG_ON, fixes > the issue reported. > > [1] http://www.redhat.com/archives/dm-devel/2011-September/msg00154.html > > Reported-by: Christophe Saout <christophe@xxxxxxxx> > Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Thank you for fixing this, but one curiosity, what happens for !flush cloned requests? Is someone else responsible for kicking the queue? -- tejun -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
