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Groups > linux.kernel > #1441813

[PATCH v3] libnvdimm, pmem: use REQ_FUA, REQ_FLUSH for nvdimm_flush()

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Given that nvdimm_flush() has higher overhead than wmb_pmem() (pointer
chasing through nd_region), and that we otherwise assume a platform has
ADR capability when flush hints are not present, move nvdimm_flush() to
REQ_FLUSH context.

Note that we still arrange for nvdimm_flush() to be called even in the
ADR case. We need at least once wmb() fence to push buffered writes in
the cpu out to the ADR protected domain.

Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---

Change since v2: arrange for wmb() to be called for flushing in the ADR case

 drivers/nvdimm/pmem.c |   16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index e303655f243e..9d9c1beef020 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -113,6 +113,11 @@ static int pmem_do_bvec(struct pmem_device *pmem, struct page *page,
 	return rc;
 }
 
+/* account for REQ_FLUSH rename, replace with REQ_PREFLUSH after v4.8-rc1 */
+#ifndef REQ_FLUSH
+#define REQ_FLUSH REQ_PREFLUSH
+#endif
+
 static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
 {
 	int rc = 0;
@@ -121,6 +126,10 @@ static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
 	struct bio_vec bvec;
 	struct bvec_iter iter;
 	struct pmem_device *pmem = q->queuedata;
+	struct nd_region *nd_region = to_region(pmem);
+
+	if (bio->bi_rw & REQ_FLUSH)
+		nvdimm_flush(nd_region);
 
 	do_acct = nd_iostat_start(bio, &start);
 	bio_for_each_segment(bvec, bio, iter) {
@@ -135,8 +144,8 @@ static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
 	if (do_acct)
 		nd_iostat_end(bio, start);
 
-	if (bio_data_dir(bio))
-		nvdimm_flush(to_region(pmem));
+	if (bio->bi_rw & REQ_FUA)
+		nvdimm_flush(nd_region);
 
 	bio_endio(bio);
 	return BLK_QC_T_NONE;
@@ -149,8 +158,6 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
 	int rc;
 
 	rc = pmem_do_bvec(pmem, page, PAGE_SIZE, 0, rw, sector);
-	if (rw & WRITE)
-		nvdimm_flush(to_region(pmem));
 
 	/*
 	 * The ->rw_page interface is subtle and tricky.  The core
@@ -279,6 +286,7 @@ static int pmem_attach_disk(struct device *dev,
 		return PTR_ERR(addr);
 	pmem->virt_addr = (void __pmem *) addr;
 
+	blk_queue_write_cache(q, true, true);
 	blk_queue_make_request(q, pmem_make_request);
 	blk_queue_physical_block_size(q, PAGE_SIZE);
 	blk_queue_max_hw_sectors(q, UINT_MAX);

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[PATCH v2 00/17] replace pcommit with ADR or directed flushing Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 17/17] pmem: kill __pmem address space Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 13/17] libnvdimm,  pmem: use nvdimm_flush() for namespace I/O writes Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 14/17] pmem: kill wmb_pmem() Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 12/17] fs/dax: remove wmb_pmem() Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 05/17] libnvdimm,  nfit: move flush hint mapping to region-device driver-data Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 11/17] libnvdimm,  pmem: flush posted-write queues on shutdown Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 15/17] Revert "KVM: x86: add pcommit support" Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 09/17] libnvdimm: cycle flush hints Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:30 +0200
  [PATCH v2 01/17] nfit: always associate flush hints Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:40 +0200
  [PATCH v2 04/17] libnvdimm,  nfit: remove nfit_spa_map() infrastructure Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:40 +0200
  [PATCH v2 06/17] tools/testing/nvdimm: simulate multiple flush  hints per-dimm Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:40 +0200
  [PATCH v2 10/17] libnvdimm, pmem: use REQ_FUA,  REQ_FLUSH for nvdimm_flush() Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:40 +0200
    [PATCH v3] libnvdimm, pmem: use REQ_FUA,  REQ_FLUSH for nvdimm_flush() Dan Williams <dan.j.williams@intel.com> - 2016-07-13 00:40 +0200
      Re: [PATCH v3] libnvdimm, pmem: use REQ_FUA, REQ_FLUSH for  nvdimm_flush() "Kani, Toshimitsu" <toshi.kani@hpe.com> - 2016-07-13 21:50 +0200
  [PATCH v2 03/17] libnvdimm: introduce devm_nvdimm_memremap(),  convert nfit_spa_map() users Dan Williams <dan.j.williams@intel.com> - 2016-07-10 05:40 +0200
    Re: [PATCH v2 03/17] libnvdimm: introduce devm_nvdimm_memremap(),  convert nfit_spa_map() users kbuild test robot <lkp@intel.com> - 2016-07-10 07:40 +0200
    [PATCH v3] libnvdimm: introduce devm_nvdimm_memremap(),  convert nfit_spa_map() users Dan Williams <dan.j.williams@intel.com> - 2016-07-13 00:30 +0200

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