[PATCH 2/2] nvme: add rotational support

["Matias Bjørling" <m@bjorling.me>]

From: Matias Bjørling <matias.bjorling@wdc.com>

Rotational devices, such as hard-drives, can be detected using
the rotational bit in the namespace independent identify namespace
data structure. Make the bit visible to the block layer through the
rotational queue setting.

Note that rotational devices typically can be used to generate random
entropy, the device is therefore also added as a block device that adds
entropy.

Signed-off-by: Matias Bjørling <matias.bjorling@wdc.com>
---
 drivers/nvme/host/core.c | 5 +++++
 include/linux/nvme.h     | 1 +
 2 files changed, 6 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 9cbef6342c39..a445f13f5a28 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -41,6 +41,7 @@ struct nvme_ns_info {
 	bool is_readonly;
 	bool is_ready;
 	bool is_removed;
+	bool is_rotational;
 };
 
 unsigned int admin_timeout = 60;
@@ -1623,6 +1624,7 @@ static int nvme_ns_info_from_id_cs_indep(struct nvme_ctrl *ctrl,
 		info->is_shared = id->nmic & NVME_NS_NMIC_SHARED;
 		info->is_readonly = id->nsattr & NVME_NS_ATTR_RO;
 		info->is_ready = id->nstat & NVME_NSTAT_NRDY;
+		info->is_rotational = id->nsfeat & NVME_NS_ROTATIONAL;
 	}
 	kfree(id);
 	return ret;
@@ -2170,6 +2172,9 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
 	else
 		lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA);
 
+	if (info->is_rotational)
+		lim.features |= BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM;
+
 	/*
 	 * Register a metadata profile for PI, or the plain non-integrity NVMe
 	 * metadata masquerading as Type 0 if supported, otherwise reject block
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 7b2ae2e43544..6d0eebb57544 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -560,6 +560,7 @@ enum {
 	NVME_NS_FLBAS_LBA_SHIFT	= 1,
 	NVME_NS_FLBAS_META_EXT	= 0x10,
 	NVME_NS_NMIC_SHARED	= 1 << 0,
+	NVME_NS_ROTATIONAL	= 1 << 4,
 	NVME_LBAF_RP_BEST	= 0,
 	NVME_LBAF_RP_BETTER	= 1,
 	NVME_LBAF_RP_GOOD	= 2,
-- 
2.46.0