On 7/1/20 1:15 AM, Dan Williams wrote:
On Tue, Jun 30, 2020 at 2:21 AM Aneesh Kumar K.V
<aneesh.ku...@linux.ibm.com> wrote:
[..]
The bio argument isn't for range based flushing, it is for flush
operations that need to complete asynchronously.
How does the block layer determine that the pmem device needs
asynchronous fushing?
set_bit(ND_REGION_ASYNC, &ndr_desc.flags);
and dax_synchronous(dev)
Yes, but I think it is overkill to have an indirect function call just
for a single instruction.
How about something like this instead, to share a common pmem_wmb()
across x86 and powerpc.
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 20ff30c2ab93..b14009060c83 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1180,6 +1180,13 @@ int nvdimm_flush(struct nd_region *nd_region,
struct bio *bio)
{
int rc = 0;
+ /*
+ * pmem_wmb() is needed to 'sfence' all previous writes such
+ * that they are architecturally visible for the platform buffer
+ * flush.
+ */
+ pmem_wmb();
+
if (!nd_region->flush)
rc = generic_nvdimm_flush(nd_region);
else {
@@ -1206,17 +1213,14 @@ int generic_nvdimm_flush(struct nd_region *nd_region)
idx = this_cpu_add_return(flush_idx, hash_32(current->pid + idx, 8));
/*
- * The first wmb() is needed to 'sfence' all previous writes
- * such that they are architecturally visible for the platform
- * buffer flush. Note that we've already arranged for pmem
- * writes to avoid the cache via memcpy_flushcache(). The final
- * wmb() ensures ordering for the NVDIMM flush write.
+ * Note that we've already arranged for pmem writes to avoid the
+ * cache via memcpy_flushcache(). The final wmb() ensures
+ * ordering for the NVDIMM flush write.
*/
- wmb();
The series already convert this to pmem_wmb().
for (i = 0; i < nd_region->ndr_mappings; i++)
if (ndrd_get_flush_wpq(ndrd, i, 0))
writeq(1, ndrd_get_flush_wpq(ndrd, i, idx));
- wmb();
+ pmem_wmb();
Should this be pmem_wmb()? This is ordering the above writeq() right?
return 0;
}
This still results in two pmem_wmb() on platforms that doesn't have
flush_wpq. I was trying to avoid that by adding a nd_region->flush call
back.
-aneesh
