On 20/03/2019 20:02, Alberto Garcia wrote: > On Wed 20 Mar 2019 10:16:10 AM CET, Kevin Wolf wrote: >>> Oh, I see. Let's use a shorter chain for simplicity: >>> >>> A <- B <- C <- D <- E >> >> Written from right to left, i.e. E being the base and A the top layer? >> We usually write things the other write round, I hope this doesn't get >> too confusing later. > > Oh my... yes, of course you're right, I should have written it the other > way around: > > E <- D <- C <- B <- A > >>> 1) If we stream first from E to C we add a filter F: >>> >>> A <- B <- F <- C <- D <- E > > ( which should have been written E <- D <- C <- F <- B <- A ) > >>> Now we can't stream from C to A because F is on the way, and the F-C >>> link is frozen. >> >> Why is a frozen link a problem? The streaming operation isn't going to >> change this link, it just copies data from the subchain (including F >> and C) to A. This is not something that a frozen link should prevent. > > Not the operation itself, but the first thing that block-stream does is > freeze the chain from top (A) to base (C), so this would fail if there's > already a frozen link on the way (C <- F on this case?).
I manage the issue by removing the filter F after the chain A-C is unfrozen in the stream_prepare(). > >> So it seems frozen links allow the wrong case, but block the correct >> one? :-( > > Yes, we probably need to rethink this scenario a bit. > > Berto > -- With the best regards, Andrey Shinkevich
