diff mbox

[v6,07/13] nbd-server: Clear "can_read" when "device io" blocker is set

Message ID 1432190583-10518-8-git-send-email-famz@redhat.com
State New
Headers show

Commit Message

Fam Zheng May 21, 2015, 6:42 a.m. UTC 
So that NBD export cannot submit IO during bdrv_drain_all().

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 nbd.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

Comments

Max Reitz May 23, 2015, 4:54 p.m. UTC | #1 
On 21.05.2015 08:42, Fam Zheng wrote:
> So that NBD export cannot submit IO during bdrv_drain_all().
>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>   nbd.c | 24 ++++++++++++++++++++++++
>   1 file changed, 24 insertions(+)

Reviewed-by: Max Reitz <mreitz@redhat.com>
diff mbox

Patch

diff --git a/nbd.c b/nbd.c
index 06b501b..b5026af 100644
--- a/nbd.c
+++ b/nbd.c
@@ -160,6 +160,8 @@  struct NBDExport {
     uint32_t nbdflags;
     QTAILQ_HEAD(, NBDClient) clients;
     QTAILQ_ENTRY(NBDExport) next;
+    Notifier blocker_notifier;
+    bool io_blocked;
 
     AioContext *ctx;
 };
@@ -1053,6 +1055,22 @@  static void blk_aio_detach(void *opaque)
     exp->ctx = NULL;
 }
 
+static void nbd_op_blocker_changed(Notifier *notifier, void *data)
+{
+    BlockOpEvent *event = data;
+    NBDClient *client;
+    NBDExport *exp = container_of(notifier, NBDExport, blocker_notifier);
+
+    if (event->type != BLOCK_OP_TYPE_DEVICE_IO) {
+        return;
+    }
+    exp->io_blocked = event->blocking;
+
+    QTAILQ_FOREACH(client, &exp->clients, next) {
+        nbd_update_can_read(client);
+    }
+}
+
 NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size,
                           uint32_t nbdflags, void (*close)(NBDExport *),
                           Error **errp)
@@ -1081,6 +1099,8 @@  NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size,
      * access since the export could be available before migration handover.
      */
     blk_invalidate_cache(blk, NULL);
+    exp->blocker_notifier.notify = nbd_op_blocker_changed;
+    blk_op_blocker_add_notifier(blk, &exp->blocker_notifier);
     return exp;
 
 fail:
@@ -1132,6 +1152,7 @@  void nbd_export_close(NBDExport *exp)
     nbd_export_set_name(exp, NULL);
     nbd_export_put(exp);
     if (exp->blk) {
+        notifier_remove(&exp->blocker_notifier);
         blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
                                         blk_aio_detach, exp);
         blk_unref(exp->blk);
@@ -1455,6 +1476,9 @@  static void nbd_update_can_read(NBDClient *client)
     bool can_read = client->recv_coroutine ||
                     client->nb_requests < MAX_NBD_REQUESTS;
 
+    if (client->exp && client->exp->io_blocked) {
+        can_read = false;
+    }
     if (can_read != client->can_read) {
         client->can_read = can_read;
         nbd_set_handlers(client);