[PATCH v3 1/2] nvme: multipath: enable BLK_FEAT_ATOMIC_WRITES for multipathing

[Alan Adamson <alan.adamson@oracle.com>]

A change to QEMU resulted in all nvme controllers (single and
multi-controller subsystems) to have its CMIC.MCTRS bit set which indicates
the subsystem supports multiple controllers and it is possible a namespace
can be shared between those multiple controllers in a multipathed
configuration.

When a namespace of a CMIC.MCTRS enabled subsystem is allocated, a
multipath node is created.  The queue limits for this node are inherited
from the namespace being allocated. When inheriting queue limits, the
features being inherited need to be specified. The atomic write feature
(BLK_FEAT_ATOMIC_WRITES) was not specified so the atomic queue limits
were not inherited by the multipath disk node which resulted in the sysfs
atomic write attributes being zeroed. The fix is to include
BLK_FEAT_ATOMIC_WRITES in the list of features to be inherited.

Signed-off-by: Alan Adamson <alan.adamson@oracle.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
---
 drivers/nvme/host/multipath.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 250f3da67cc9..cf0ef4745564 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -638,7 +638,8 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
 
 	blk_set_stacking_limits(&lim);
 	lim.dma_alignment = 3;
-	lim.features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT | BLK_FEAT_POLL;
+	lim.features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT |
+		BLK_FEAT_POLL | BLK_FEAT_ATOMIC_WRITES;
 	if (head->ids.csi == NVME_CSI_ZNS)
 		lim.features |= BLK_FEAT_ZONED;
 
-- 
2.43.5