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authorKevin Wolf <kwolf@redhat.com>2020-09-24 17:27:03 +0200
committerKevin Wolf <kwolf@redhat.com>2020-10-02 15:46:40 +0200
commitbc4ee65b8c309ed6a726e3ea1b73f7fa31b4bb95 (patch)
tree7c938b2e893712c8740f0a7b9ac624bc4a92b65f /block/export
parenta6ff7989662d659aed0888670e77e68cb8c9bd81 (diff)
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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>
Diffstat (limited to 'block/export')
-rw-r--r--block/export/export.c86
1 files changed, 84 insertions, 2 deletions
diff --git a/block/export/export.c b/block/export/export.c
index 6b2b290..e94a68c 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -24,6 +24,10 @@ static const BlockExportDriver *blk_exp_drivers[] = {
&blk_exp_nbd,
};
+/* Only accessed from the main thread */
+static QLIST_HEAD(, BlockExport) block_exports =
+ QLIST_HEAD_INITIALIZER(block_exports);
+
static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
{
int i;
@@ -61,6 +65,7 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
return NULL;
}
+ QLIST_INSERT_HEAD(&block_exports, exp, next);
return exp;
}
@@ -71,14 +76,91 @@ void blk_exp_ref(BlockExport *exp)
exp->refcount++;
}
+/* Runs in the main thread */
+static void blk_exp_delete_bh(void *opaque)
+{
+ BlockExport *exp = opaque;
+ AioContext *aio_context = exp->ctx;
+
+ aio_context_acquire(aio_context);
+
+ assert(exp->refcount == 0);
+ QLIST_REMOVE(exp, next);
+ exp->drv->delete(exp);
+ g_free(exp);
+
+ aio_context_release(aio_context);
+}
+
/* Callers must hold exp->ctx lock */
void blk_exp_unref(BlockExport *exp)
{
assert(exp->refcount > 0);
if (--exp->refcount == 0) {
- exp->drv->delete(exp);
- g_free(exp);
+ /* Touch the block_exports list only in the main thread */
+ aio_bh_schedule_oneshot(qemu_get_aio_context(), blk_exp_delete_bh,
+ exp);
+ }
+}
+
+/*
+ * Drops the user reference to the export and requests that all client
+ * connections and other internally held references start to shut down. When
+ * the function returns, there may still be active references while the export
+ * is in the process of shutting down.
+ *
+ * Acquires exp->ctx internally. Callers must *not* hold the lock.
+ */
+void blk_exp_request_shutdown(BlockExport *exp)
+{
+ AioContext *aio_context = exp->ctx;
+
+ aio_context_acquire(aio_context);
+ exp->drv->request_shutdown(exp);
+ aio_context_release(aio_context);
+}
+
+/*
+ * Returns whether a block export of the given type exists.
+ * type == BLOCK_EXPORT_TYPE__MAX checks for an export of any type.
+ */
+static bool blk_exp_has_type(BlockExportType type)
+{
+ BlockExport *exp;
+
+ if (type == BLOCK_EXPORT_TYPE__MAX) {
+ return !QLIST_EMPTY(&block_exports);
+ }
+
+ QLIST_FOREACH(exp, &block_exports, next) {
+ if (exp->drv->type == type) {
+ return true;
+ }
}
+
+ return false;
+}
+
+/* type == BLOCK_EXPORT_TYPE__MAX for all types */
+void blk_exp_close_all_type(BlockExportType type)
+{
+ BlockExport *exp, *next;
+
+ assert(in_aio_context_home_thread(qemu_get_aio_context()));
+
+ QLIST_FOREACH_SAFE(exp, &block_exports, next, next) {
+ if (type != BLOCK_EXPORT_TYPE__MAX && exp->drv->type != type) {
+ continue;
+ }
+ blk_exp_request_shutdown(exp);
+ }
+
+ AIO_WAIT_WHILE(NULL, blk_exp_has_type(type));
+}
+
+void blk_exp_close_all(void)
+{
+ blk_exp_close_all_type(BLOCK_EXPORT_TYPE__MAX);
}
void qmp_block_export_add(BlockExportOptions *export, Error **errp)