block/export: Add blk_exp_close_all(_type)

This adds a function to shut down all block exports, and another one to
shut down the block exports of a single type. The latter is used for now
when stopping the NBD server. As soon as we implement support for
multiple NBD servers, we'll need a per-server list of exports and it
will be replaced by a function using that.

As a side effect, the BlockExport layer has a list tracking all existing
exports now. closed_exports loses its only user and can go away.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-18-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 15 insertions, 2 deletions

diff --git a/include/block/export.h b/include/block/export.h
index cf9b1c9dad..6fffcb5651 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -15,6 +15,7 @@
 #define BLOCK_EXPORT_H
 
 #include "qapi/qapi-types-block-export.h"
+#include "qemu/queue.h"
 
 typedef struct BlockExport BlockExport;
 
@@ -36,6 +37,14 @@ typedef struct BlockExportDriver {
      * references have been dropped.
      */
     void (*delete)(BlockExport *);
+
+    /*
+     * Start to disconnect all clients and drop other references held
+     * internally by the export driver. When the function returns, there may
+     * still be active references while the export is in the process of
+     * shutting down.
+     */
+    void (*request_shutdown)(BlockExport *);
 } BlockExportDriver;
 
 struct BlockExport {
@@ -50,10 +59,16 @@ struct BlockExport {
 
     /* The AioContext whose lock protects this BlockExport object. */
     AioContext *ctx;
+
+    /* List entry for block_exports */
+    QLIST_ENTRY(BlockExport) next;
 };
 
 BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
 void blk_exp_ref(BlockExport *exp);
 void blk_exp_unref(BlockExport *exp);
+void blk_exp_request_shutdown(BlockExport *exp);
+void blk_exp_close_all(void);
+void blk_exp_close_all_type(BlockExportType type);
 
 #endif
diff --git a/include/block/nbd.h b/include/block/nbd.h
index fc2c153d5b..0b9f3e5d4e 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -337,12 +337,10 @@ int nbd_export_new(BlockExport *blk_exp, BlockDriverState *bs,
                    const char *bitmap, bool readonly, bool shared,
                    bool writethrough, Error **errp);
 void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
-void nbd_export_close(NBDExport *exp);
 void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
 
 AioContext *nbd_export_aio_context(NBDExport *exp);
 NBDExport *nbd_export_find(const char *name);
-void nbd_export_close_all(void);
 
 void nbd_client_new(QIOChannelSocket *sioc,
                     QCryptoTLSCreds *tlscreds,