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. Mikulas > static int persistent_memory_claim(struct dm_writecache *wc) > { > int r; > @@ -337,6 +338,12 @@ static int persistent_memory_claim(struct dm_writecache *wc) > err1: > return r; > } > +#else > +static int persistent_memory_claim(struct dm_writecache *wc) > +{ > + BUG(); > +} > +#endif > > static void persistent_memory_release(struct dm_writecache *wc) > { > @@ -1901,16 +1908,17 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv) > if (!strcasecmp(string, "s")) { > wc->pmem_mode = false; > } else if (!strcasecmp(string, "p")) { > -#ifdef CONFIG_ARCH_HAS_PMEM_API > +#if defined(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_DAX_DRIVER) > wc->pmem_mode = true; > wc->writeback_fua = true; > #else > /* > - * If the architecture doesn't support persistent memory, this > - * driver can only be used in SSD-only mode. > + * If the architecture doesn't support persistent memory or > + * the kernel doesn't support any DAX drivers, this driver can > + * only be used in SSD-only mode. > */ > r = -EOPNOTSUPP; > - ti->error = "Persistent memory not supported on this architecture"; > + ti->error = "Persistent memory or DAX not supported on this system"; > goto bad; > #endif > } else { > -- > 2.14.3 >
