I meant, which kernel source version did you start with and which patches did you apply?
I had no success with patching latest jessie kernel 3.16.7-ckt20 directly with Eric Wheeler summary pull (http://article.gmane.org/gmane.linux.kernel.bcache.devel/3292) - "maybe earlier" not working :), so I took all the patches (mostly from Ken Overstreet) from https://github.com/torvalds/linux/commits/v3.17/drivers/md/bcache since:
--- arch: Mass conversion of smp_mb__*() … Peter Zijlstra committed with Ingo Molnar on 17 Mar 2014 --- (this was last patch for 3.16)All the changes are made in same folder, except some minor header changes in kernel. "bcache: Make sure to pass GFP_WAIT to mempool_alloc()" patch indicates reverse patch, answered n and applied anyway. Checked btree.rej/btree.c file (line with GFP_NOIO) and checked against same code from https://github.com/torvalds/linux/tree/v3.17/drivers/md/bcache.c - it was the same.
Then I took these 8 stability patches from Eric Wheeler (https://github.com/torvalds/linux/compare/master...ewheelerinc:bcache-patches-for-3.17) and they pass through.
Martin