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
--
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