block: move blk_exp_close_all() to qemu_cleanup()

Move blk_exp_close_all() from bdrv_close() to qemu_cleanup(), before
bdrv_drain_all_begin().

Export drivers may have coroutines yielding at some point in the block
layer, so we need to shut them down before draining the block layer,
as otherwise they may get stuck blk_wait_while_drained().

RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1900505
Signed-off-by: Sergio Lopez <slp@redhat.com>
Message-Id: <20210201125032.44713-3-slp@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

4 files changed, 11 insertions, 1 deletions

diff --git a/block.c b/block.c
index 5c428e1595..4e52b1c588 100644
--- a/block.c
+++ b/block.c
@@ -4435,7 +4435,6 @@ static void bdrv_close(BlockDriverState *bs)
 void bdrv_close_all(void)
 {
     assert(job_next(NULL) == NULL);
-    blk_exp_close_all();
 
     /* Drop references from requests still in flight, such as canceled block
      * jobs whose AIO context has not been polled yet */
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 0d513cb38c..608c63e82a 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -503,6 +503,7 @@ static const char *socket_activation_validate_opts(const char *device,
 static void qemu_nbd_shutdown(void)
 {
     job_cancel_sync_all();
+    blk_exp_close_all();
     bdrv_close_all();
 }
 
diff --git a/softmmu/runstate.c b/softmmu/runstate.c
index beee050815..a7fcb603f7 100644
--- a/softmmu/runstate.c
+++ b/softmmu/runstate.c
@@ -25,6 +25,7 @@
 #include "qemu/osdep.h"
 #include "audio/audio.h"
 #include "block/block.h"
+#include "block/export.h"
 #include "chardev/char.h"
 #include "crypto/cipher.h"
 #include "crypto/init.h"
@@ -785,6 +786,14 @@ void qemu_cleanup(void)
     migration_shutdown();
 
     /*
+     * Close the exports before draining the block layer. The export
+     * drivers may have coroutines yielding on it, so we need to clean
+     * them up before the drain, as otherwise they may be get stuck in
+     * blk_wait_while_drained().
+     */
+    blk_exp_close_all();
+
+    /*
      * We must cancel all block jobs while the block layer is drained,
      * or cancelling will be affected by throttling and thus may block
      * for an extended period of time.
diff --git a/storage-daemon/qemu-storage-daemon.c b/storage-daemon/qemu-storage-daemon.c
index e0c87edbdd..d8d172cc60 100644
--- a/storage-daemon/qemu-storage-daemon.c
+++ b/storage-daemon/qemu-storage-daemon.c
@@ -314,6 +314,7 @@ int main(int argc, char *argv[])
         main_loop_wait(false);
     }
 
+    blk_exp_close_all();
     bdrv_drain_all_begin();
     bdrv_close_all();