[Minios-devel] [UNIKRAFT PATCH v3 14/17] plat/xen/drivers/blk: Flush requests

[Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>]

This patch introduces the flush requests.
This operation garantees that all previous write requests are finished.

Signed-off-by: Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>
---
 plat/xen/drivers/blk/blkfront.c    | 25 +++++++++++++++++++++++++
 plat/xen/drivers/blk/blkfront.h    |  8 ++++++++
 plat/xen/drivers/blk/blkfront_xs.c | 15 +++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/plat/xen/drivers/blk/blkfront.c b/plat/xen/drivers/blk/blkfront.c
index 2129f191..5866c8e7 100644
--- a/plat/xen/drivers/blk/blkfront.c
+++ b/plat/xen/drivers/blk/blkfront.c
@@ -150,6 +150,29 @@ static int blkfront_request_write(struct blkfront_request 
*blkfront_req,
        return rc;
 }
 
+static int blkfront_request_flush(struct blkfront_request *blkfront_req,
+               struct blkif_request *ring_req)
+{
+       struct blkfront_dev *dev;
+       struct uk_blkdev_queue *queue;
+
+       UK_ASSERT(ring_req);
+
+       queue = blkfront_req->queue;
+       dev = queue->dev;
+       if (dev->barrier)
+               ring_req->operation = BLKIF_OP_WRITE_BARRIER;
+       else if (dev->flush)
+               ring_req->operation = BLKIF_OP_FLUSH_DISKCACHE;
+       else
+               return -ENOTSUP;
+
+       ring_req->nr_segments = 0;
+       ring_req->sector_number = 0;
+
+       return 0;
+}
+
 static int blkfront_queue_enqueue(struct uk_blkdev_queue *queue,
                struct uk_blkreq *req)
 {
@@ -179,6 +202,8 @@ static int blkfront_queue_enqueue(struct uk_blkdev_queue 
*queue,
        if (req->operation == UK_BLKDEV_READ ||
                        req->operation == UK_BLKDEV_WRITE)
                rc = blkfront_request_write(blkfront_req, ring_req);
+       else if (req->operation == UK_BLKDEV_FFLUSH)
+               rc =  blkfront_request_flush(blkfront_req, ring_req);
        else
                rc = -EINVAL;
 
diff --git a/plat/xen/drivers/blk/blkfront.h b/plat/xen/drivers/blk/blkfront.h
index ec727fc8..93d2905d 100644
--- a/plat/xen/drivers/blk/blkfront.h
+++ b/plat/xen/drivers/blk/blkfront.h
@@ -89,6 +89,14 @@ struct blkfront_dev {
        struct uk_blkdev blkdev;
        /* Blkfront device number from Xenstore path. */
        blkif_vdev_t    handle;
+       /* Value which indicates that the backend can process requests with the
+        * BLKIF_OP_WRITE_BARRIER request opcode.
+        */
+       int barrier;
+       /* Value which indicates that the backend can process requests with the
+        * BLKIF_OP_WRITE_FLUSH_DISKCACHE request opcode.
+        */
+       int flush;
        /* Number of configured queues used for requests */
        uint16_t nb_queues;
        /* Vector of queues used for communication with backend */
diff --git a/plat/xen/drivers/blk/blkfront_xs.c 
b/plat/xen/drivers/blk/blkfront_xs.c
index 69a2df9d..e93665c8 100644
--- a/plat/xen/drivers/blk/blkfront_xs.c
+++ b/plat/xen/drivers/blk/blkfront_xs.c
@@ -191,6 +191,21 @@ static int blkfront_xb_get_capabilities(struct 
blkfront_dev *blkdev)
                return err;
        }
 
+       err = xs_scanf(XBT_NIL, xendev->otherend, "feature-flush-cache",
+                                       "%d", &blkdev->flush);
+       if (err < 0) {
+               uk_pr_err("Failed to read feature-flush-cache from xs: %d\n",
+                               err);
+               return err;
+       }
+
+       err = xs_scanf(XBT_NIL, xendev->otherend, "feature-barrier",
+                                       "%d", &blkdev->barrier);
+       if (err < 0) {
+               uk_pr_err("Failed to read feature-barrier from xs: %d\n", err);
+               return err;
+       }
+
        mode = xs_read(XBT_NIL, xendev->otherend, "mode");
        if (PTRISERR(mode)) {
                uk_pr_err("Failed to read mode from xs: %d.\n", err);
-- 
2.17.1


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