From 0da112402efe63e09fdd6ed43aa026d5b625988f Mon Sep 17 00:00:00 2001
From: yexiao <yexiao7@huawei.com>
Date: Thu, 21 Jan 2021 15:46:53 +0800
Subject: [PATCH] virtio_blk: Add support for retry on errors

Insert failed requests into device's list for later retry and handle
queued requests to implement retry_request_cb.

Signed-off-by: Jiahui Cen <cenjiahui(a)huawei.com>
Signed-off-by: Ying Fang <fangying1(a)huawei.com>
Signed-off-by: Alex Chen <alex.chen@huawei.com>
---
 hw/block/virtio-blk.c | 47 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 44 insertions(+), 3 deletions(-)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index a1f8e15522..1ebc9188c0 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -90,6 +90,10 @@ static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
             block_acct_failed(blk_get_stats(s->blk), &req->acct);
         }
         virtio_blk_free_request(req);
+    } else if (action == BLOCK_ERROR_ACTION_RETRY) {
+        req->mr_next = NULL;
+        req->next = s->rq;
+        s->rq = req;
     }
 
     blk_error_action(s->blk, action, is_read, error);
@@ -131,6 +135,7 @@ static void virtio_blk_rw_complete(void *opaque, int ret)
             }
         }
 
+        blk_error_retry_reset_timeout(s->blk);
         virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
         block_acct_done(blk_get_stats(s->blk), &req->acct);
         virtio_blk_free_request(req);
@@ -150,6 +155,7 @@ static void virtio_blk_flush_complete(void *opaque, int ret)
         }
     }
 
+    blk_error_retry_reset_timeout(s->blk);
     virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
     block_acct_done(blk_get_stats(s->blk), &req->acct);
     virtio_blk_free_request(req);
@@ -172,6 +178,7 @@ static void virtio_blk_discard_write_zeroes_complete(void *opaque, int ret)
         }
     }
 
+    blk_error_retry_reset_timeout(s->blk);
     virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
     if (is_write_zeroes) {
         block_acct_done(blk_get_stats(s->blk), &req->acct);
@@ -1183,12 +1190,12 @@ static void virtio_blk_dma_restart_bh(void *opaque)
 {
     VirtIOBlock *s = opaque;
 
-    VirtIOBlockReq *req = s->rq;
+    VirtIOBlockReq *req;
     MultiReqBuffer mrb = {};
 
-    s->rq = NULL;
-
     aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
+    req = s->rq;
+    s->rq = NULL;
     while (req) {
         VirtIOBlockReq *next = req->next;
         if (virtio_blk_handle_request(req, &mrb)) {
@@ -1541,10 +1548,44 @@ static void virtio_blk_drained_end(void *opaque)
     }
 }
 
+static void virtio_blk_retry_request(void *opaque)
+{
+    VirtIOBlock *s = VIRTIO_BLK(opaque);
+
+    VirtIOBlockReq *req;
+    MultiReqBuffer mrb = {};
+
+    aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
+    req = s->rq;
+    s->rq = NULL;
+    while (req) {
+        VirtIOBlockReq *next = req->next;
+        if (virtio_blk_handle_request(req, &mrb)) {
+            /* Device is now broken and won't do any processing until it gets
+             * reset. Already queued requests will be lost: let's purge them.
+             */
+            while (req) {
+                next = req->next;
+                virtqueue_detach_element(req->vq, &req->elem, 0);
+                virtio_blk_free_request(req);
+                req = next;
+            }
+            break;
+        }
+        req = next;
+    }
+
+    if (mrb.num_reqs) {
+        virtio_blk_submit_multireq(s, &mrb);
+    }
+    aio_context_release(blk_get_aio_context(s->conf.conf.blk));
+}
+
 static const BlockDevOps virtio_block_ops = {
     .resize_cb     = virtio_blk_resize,
     .drained_begin = virtio_blk_drained_begin,
     .drained_end   = virtio_blk_drained_end,
+    .retry_request_cb = virtio_blk_retry_request,
 };
 
 static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
-- 
2.27.0