On Tue, May 29 2018 at 2:40pm -0400, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > On Tue, May 29, 2018 at 11:08 AM, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > > On Tue, May 29 2018 at 1:52pm -0400, > > Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> wrote: > > > >> As reported by Arnd (https://lkml.org/lkml/2018/5/28/1697), dm-writecache > >> will fail with link errors in configs where DAX isn't present: > >> > >> drivers/md/dm-writecache.o: In function `writecache_ctr': > >> dm-writecache.c:(.text+0x1fdc): undefined reference to `dax_read_lock' > >> dm-writecache.c:(.text+0x2004): undefined reference to `dax_direct_access' > >> dm-writecache.c:(.text+0x21cc): undefined reference to `dax_read_unlock' > >> > >> Fix this by following the lead of the other DM modules and wrapping calls > >> to the generic DAX code in #if IS_ENABLED(CONFIG_DAX_DRIVER) blocks. > >> > >> We also expand the failure case for the 'p' (persistent memory) flag so > >> that fails on both architectures that don't support persistent memory and > >> on kernels that don't have DAX support configured. This prevents us from > >> ever hitting the BUG() in the persistent_memory_claim() stub. > >> > >> Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > >> Reported-by: Arnd Bergmann <arnd@xxxxxxxx> > > > > Thanks, I've picked this up. > > ...I assume you're also going to let the 'pmem api' discussion resolve > before this all goes upstream? Yeah, I'm going to pivot back to that and put time to it shortly. If dm-writecache has to wait another cycle (so 4.19 inclusion), while unfortunate, it wouldn't be the end of the world. I look forward to your continued help, thanks. Mike
