[PATCH] hw/block/nvme: conditionally enable DULBE for zoned namespaces

* [PATCH] hw/block/nvme: conditionally enable DULBE for zoned namespaces
@ 2021-01-11 18:09 Klaus Jensen
  2021-01-14 23:39 ` Keith Busch
  0 siblings, 1 reply; 3+ messages in thread
From: Klaus Jensen @ 2021-01-11 18:09 UTC (permalink / raw)
  To: qemu-devel
  Cc: Kevin Wolf, qemu-block, Dmitry Fomichev, Klaus Jensen, Max Reitz,
	Keith Busch, Klaus Jensen

From: Klaus Jensen <k.jensen@samsung.com>

The device uses the BDRV_BLOCK_ZERO flag to determine the "deallocated"
status of logical blocks. Since the zoned namespaces command set
specification defines that logical blocks SHALL be marked as deallocated
when the zone is in the Empty or Offline states, DULBE can only be
supported if the zone size is a multiple of the calculated deallocation
granularity (reported in NPDG) which depends on the underlying block
device cluster size (if applicable) or the configured
discard_granularity.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
 hw/block/nvme-ns.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/hw/block/nvme-ns.c b/hw/block/nvme-ns.c
index a4972ac23d8f..274eaf61b721 100644
--- a/hw/block/nvme-ns.c
+++ b/hw/block/nvme-ns.c
@@ -16,6 +16,7 @@
 #include "qemu/units.h"
 #include "qemu/cutils.h"
 #include "qemu/log.h"
+#include "qemu/error-report.h"
 #include "hw/block/block.h"
 #include "hw/pci/pci.h"
 #include "sysemu/sysemu.h"
@@ -226,6 +227,22 @@ static void nvme_ns_init_zoned(NvmeCtrl *n, NvmeNamespace *ns, int lba_index)
     ns->id_ns.ncap = ns->id_ns.nsze;
     ns->id_ns.nuse = ns->id_ns.ncap;
 
+    /*
+     * The device uses the BDRV_BLOCK_ZERO flag to determine the "deallocated"
+     * status of logical blocks. Since the spec defines that logical blocks
+     * SHALL be deallocated when then zone is in the Empty or Offline states,
+     * we can only support DULBE if the zone size is a multiple of the
+     * calculated NPDG.
+     */
+    if (ns->zone_size % (ns->id_ns.npdg + 1)) {
+        warn_report("the zone size (%"PRIu64" blocks) is not a multiple of "
+                    "the calculated deallocation granularity "
+                    "(%"PRIu16" blocks); DULBE support disabled",
+                    ns->zone_size, ns->id_ns.npdg + 1);
+
+        ns->id_ns.nsfeat &= ~0x4;
+    }
+
     ns->id_ns_zoned = id_ns_z;
 }
 
-- 
2.30.0



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