On Wed, May 30 2018 at 8:22am -0400, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > > On Tue, 29 May 2018, Ross Zwisler 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> > > --- > > drivers/md/dm-writecache.c | 16 ++++++++++++---- > > 1 file changed, 12 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c > > index 92af65fdf4af..1c2b53ae1a96 100644 > > --- a/drivers/md/dm-writecache.c > > +++ b/drivers/md/dm-writecache.c > > @@ -253,6 +253,7 @@ static void wc_unlock(struct dm_writecache *wc) > > mutex_unlock(&wc->lock); > > } > > > > +#if IS_ENABLED(CONFIG_DAX_DRIVER) > > We already have #if(n)def DM_WRITECACHE_ONLY_SSD > > There is no need to use another macro for the same purpose. I removed DM_WRITECACHE_ONLY_SSD because it wasn't needed, this is the split out commit that I have since folded in: https://git.kernel.org/pub/scm/linux/kernel/git/snitzer/linux.git/commit/?h=dm-4.18-writecache-wip&id=e7fd3d1c05659f7e1295178290fbdaebf36becdc Ross's patch effectively builds ontop of that. Mike
