[PATCH 1/2] virtio_blk: add fua write support

[Alberto Faria <afaria@redhat.com>]

Add the new virtio-blk request FUA flag uapi definitions and
corresponding virtio-blk support.

Signed-off-by: Alberto Faria <afaria@redhat.com>
---
 drivers/block/virtio_blk.c      | 15 +++++++++++++--
 include/uapi/linux/virtio_blk.h | 13 +++++++++++--
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index c8bfbf8435ac7..f2ef0fdba181d 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -248,7 +248,10 @@ static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
 		return BLK_STS_NOTSUPP;
 
 	/* Set fields for all request types */
-	vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
+	if (virtio_has_feature(vdev, VIRTIO_BLK_F_REQ_FLAGS))
+		vbr->out_hdr.flags = 0;
+	else
+		vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
 
 	switch (req_op(req)) {
 	case REQ_OP_READ:
@@ -258,6 +261,9 @@ static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
 	case REQ_OP_WRITE:
 		type = VIRTIO_BLK_T_OUT;
 		sector = blk_rq_pos(req);
+		if (req->cmd_flags & REQ_FUA)
+			vbr->out_hdr.flags |= cpu_to_virtio32(vdev,
+				BIT(VIRTIO_BLK_REQ_FLAG_OUT_FUA));
 		break;
 	case REQ_OP_FLUSH:
 		type = VIRTIO_BLK_T_FLUSH;
@@ -1508,6 +1514,10 @@ static int virtblk_probe(struct virtio_device *vdev)
 	if (virtblk_get_cache_mode(vdev))
 		lim.features |= BLK_FEAT_WRITE_CACHE;
 
+	if (virtio_has_feature(vdev, VIRTIO_BLK_F_REQ_FLAGS) &&
+	    virtio_has_feature(vdev, VIRTIO_BLK_F_REQ_FLAGS_OUT_FUA))
+		lim.features |= BLK_FEAT_FUA;
+
 	vblk->disk = blk_mq_alloc_disk(&vblk->tag_set, &lim, vblk);
 	if (IS_ERR(vblk->disk)) {
 		err = PTR_ERR(vblk->disk);
@@ -1672,7 +1682,8 @@ static unsigned int features[] = {
 	VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
 	VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
 	VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
-	VIRTIO_BLK_F_SECURE_ERASE, VIRTIO_BLK_F_ZONED,
+	VIRTIO_BLK_F_SECURE_ERASE, VIRTIO_BLK_F_ZONED, VIRTIO_BLK_F_REQ_FLAGS,
+	VIRTIO_BLK_F_REQ_FLAGS_OUT_FUA,
 };
 
 static struct virtio_driver virtio_blk = {
diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h
index 3744e4da1b2a7..c5047e6a9a9bc 100644
--- a/include/uapi/linux/virtio_blk.h
+++ b/include/uapi/linux/virtio_blk.h
@@ -42,6 +42,8 @@
 #define VIRTIO_BLK_F_WRITE_ZEROES	14	/* WRITE ZEROES is supported */
 #define VIRTIO_BLK_F_SECURE_ERASE	16 /* Secure Erase is supported */
 #define VIRTIO_BLK_F_ZONED		17	/* Zoned block device */
+#define VIRTIO_BLK_F_REQ_FLAGS		18	/* Request flags supported */
+#define VIRTIO_BLK_F_REQ_FLAGS_OUT_FUA	19	/* FUA flag supported */
 
 /* Legacy feature bits */
 #ifndef VIRTIO_BLK_NO_LEGACY
@@ -211,6 +213,9 @@ struct virtio_blk_config {
 #define VIRTIO_BLK_T_BARRIER	0x80000000
 #endif /* !VIRTIO_BLK_NO_LEGACY */
 
+/* Request flag bits */
+#define VIRTIO_BLK_REQ_FLAG_OUT_FUA	0
+
 /*
  * This comes first in the read scatter-gather list.
  * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated,
@@ -219,8 +224,12 @@ struct virtio_blk_config {
 struct virtio_blk_outhdr {
 	/* VIRTIO_BLK_T* */
 	__virtio32 type;
-	/* io priority. */
-	__virtio32 ioprio;
+	union {
+		/* io priority. */
+		__virtio32 ioprio;
+		/* Request flags. */
+		__virtio32 flags;
+	};
 	/* Sector (ie. 512 byte offset) */
 	__virtio64 sector;
 };
-- 
2.56.0