On Thu, May 31 2018 at 4:16am -0400,
Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
>
>
> On Wed, 30 May 2018, Mike Snitzer wrote:
>
> > On Wed, May 30 2018 at 10:09P -0400,
> > Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
> >
> > > And what about this?
> > > #define WC_MODE_PMEM(wc) ((wc)->pmem_mode)
> > >
> > > The code that I had just allowed the compiler to optimize out
> > > persistent-memory code if we have DM_WRITECACHE_ONLY_SSD defined - and you
> > > deleted it.
> > >
> > > Most architectures don't have persistent memory and the dm-writecache
> > > driver could work in ssd-only mode on them. On these architectures, I
> > > define
> > > #define WC_MODE_PMEM(wc) false
> > > - and the compiler will just automatically remove the tests for that
> > > condition and the unused branch. It does also eliminate unused static
> > > functions.
> >
> > Here is the patch that I just folded into the rebased version of
> > dm-writecache now in the dm-4.18 branch.
> >
> > (I rebased ontop of Jens' latest block tree for 4.18 that now includes
> > the mempool_init changes, etc.)
> >
> > ---
> > drivers/md/dm-writecache.c | 17 +++++++++++++++--
> > 1 file changed, 15 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
> > index fcbfaf7c27ec..691b5ffb799f 100644
> > --- a/drivers/md/dm-writecache.c
> > +++ b/drivers/md/dm-writecache.c
> > @@ -34,13 +34,21 @@
> > #define BITMAP_GRANULARITY PAGE_SIZE
> > #endif
> >
> > +#if defined(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_DAX_DRIVER)
> > +#define DM_WRITECACHE_HAS_PMEM
> > +#endif
> > +
> > +#ifdef DM_WRITECACHE_HAS_PMEM
> > #define pmem_assign(dest, src) \
> > do { \
> > typeof(dest) uniq = (src); \
> > memcpy_flushcache(&(dest), &uniq, sizeof(dest)); \
> > } while (0)
> > +#else
> > +#define pmem_assign(dest, src) ((dest)) = (src))
> > +#endif
> >
> > -#if defined(__HAVE_ARCH_MEMCPY_MCSAFE) && defined(CONFIG_ARCH_HAS_PMEM_API)
> > +#if defined(__HAVE_ARCH_MEMCPY_MCSAFE) && defined(DM_WRITECACHE_HAS_PMEM)
> > #define DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
> > #endif
> >
> > @@ -87,8 +95,13 @@ struct wc_entry {
> > #endif
> > };
> >
> > +#ifdef DM_WRITECACHE_HAS_PMEM
> > #define WC_MODE_PMEM(wc) ((wc)->pmem_mode)
> > #define WC_MODE_FUA(wc) ((wc)->writeback_fua)
> > +#else
> > +#define WC_MODE_PMEM(wc) false
> > +#define WC_MODE_FUA(wc) false
> > +#endif
> > #define WC_MODE_SORT_FREELIST(wc) (!WC_MODE_PMEM(wc))
> >
> > struct dm_writecache {
> > @@ -1857,7 +1870,7 @@ 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")) {
> > -#if defined(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_DAX_DRIVER)
> > +#ifdef DM_WRITECACHE_HAS_PMEM
> > wc->pmem_mode = true;
> > wc->writeback_fua = true;
> > #else
> > --
> > 2.15.0
>
> OK.
>
> I think that persistent_memory_claim should also be conditioned based on
> DM_WRITECACHE_HAS_PMEM - i.e. if we have DM_WRITECACHE_HAS_PMEM, we don't
> need to use other ifdefs.
>
> Is there some difference between "#if IS_ENABLED(CONFIG_OPTION)" and
> "#if defined(CONFIG_OPTION)"?
Not that I'm aware of:
#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
Here is the incremental patch I just folded in:
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index fd3bc232b7d6..f2ae02f22c43 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -34,7 +34,7 @@
#define BITMAP_GRANULARITY PAGE_SIZE
#endif
-#if defined(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_DAX_DRIVER)
+#if IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_DAX_DRIVER)
#define DM_WRITECACHE_HAS_PMEM
#endif
@@ -218,7 +218,7 @@ static void wc_unlock(struct dm_writecache *wc)
mutex_unlock(&wc->lock);
}
-#if IS_ENABLED(CONFIG_DAX_DRIVER)
+#ifdef DM_WRITECACHE_HAS_PMEM
static int persistent_memory_claim(struct dm_writecache *wc)
{
int r;
--
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