[Qemu-devel] [PATCH 2/2] block: remove legacy_dinfo at blk_detach_dev time

[Paolo Bonzini <pbonzini@redhat.com>]

Currently, blockdev_del_drive does a blk_unref (and before it
blockdev_auto_del did the same) that will cause blk_delete to be called
and the DriveInfo to be freed.  But really, we want to free the drive info
as soon as the device is detached, even if there are other references
for whatever reason, so that the QemuOpts are freed as well and the id
can be reused.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/block-backend.c     | 14 ++++++++++----
 blockdev.c                |  7 ++++---
 include/sysemu/blockdev.h |  1 +
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 9889e81..a1db52b 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -62,8 +62,6 @@ static const AIOCBInfo block_backend_aiocb_info = {
     .aiocb_size = sizeof(BlockBackendAIOCB),
 };
 
-static void drive_info_del(DriveInfo *dinfo);
-
 /* All the BlockBackends (except for hidden ones) */
 static QTAILQ_HEAD(, BlockBackend) blk_backends =
     QTAILQ_HEAD_INITIALIZER(blk_backends);
@@ -160,6 +158,7 @@ static void blk_delete(BlockBackend *blk)
 {
     assert(!blk->refcnt);
     assert(!blk->dev);
+    assert(!blk->legacy_dinfo);
     if (blk->bs) {
         assert(blk->bs->blk == blk);
         blk->bs->blk = NULL;
@@ -175,19 +174,26 @@ static void blk_delete(BlockBackend *blk)
         QTAILQ_REMOVE(&blk_backends, blk, link);
     }
     g_free(blk->name);
-    drive_info_del(blk->legacy_dinfo);
     block_acct_cleanup(&blk->stats);
     g_free(blk);
 }
 
-static void drive_info_del(DriveInfo *dinfo)
+void blk_release_legacy_dinfo(BlockBackend *blk)
 {
+    DriveInfo *dinfo = blk->legacy_dinfo;
+
     if (!dinfo) {
         return;
     }
     qemu_opts_del(dinfo->opts);
     g_free(dinfo->serial);
     g_free(dinfo);
+    blk->legacy_dinfo = NULL;
+
+    /* We are not interested anymore in retrieving the BlockBackend
+     * via blk_by_legacy_dinfo, so let it die.
+     */
+    blk_unref(blk);
 }
 
 int blk_get_refcnt(BlockBackend *blk)
diff --git a/blockdev.c b/blockdev.c
index a8309fb..d75be63 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -116,10 +116,10 @@ void override_max_devs(BlockInterfaceType type, int max_devs)
  */
 void blockdev_del_drive(BlockBackend *blk)
 {
-    DriveInfo *dinfo = blk_legacy_dinfo(blk);
     BlockDriverState *bs = blk_bs(blk);
     AioContext *aio_context;
 
+    blk_ref(blk);
     if (bs) {
         aio_context = bdrv_get_aio_context(bs);
         aio_context_acquire(aio_context);
@@ -131,9 +131,10 @@ void blockdev_del_drive(BlockBackend *blk)
         aio_context_release(aio_context);
     }
 
-    if (dinfo) {
-        blk_unref(blk);
+    if (blk_legacy_dinfo(blk)) {
+        blk_release_legacy_dinfo(blk);
     }
+    blk_unref(blk);
 }
 
 /**
diff --git a/include/sysemu/blockdev.h b/include/sysemu/blockdev.h
index ae7ad67..5722b9f 100644
--- a/include/sysemu/blockdev.h
+++ b/include/sysemu/blockdev.h
@@ -44,6 +44,7 @@ struct DriveInfo {
 DriveInfo *blk_legacy_dinfo(BlockBackend *blk);
 DriveInfo *blk_set_legacy_dinfo(BlockBackend *blk, DriveInfo *dinfo);
 BlockBackend *blk_by_legacy_dinfo(DriveInfo *dinfo);
+void blk_release_legacy_dinfo(BlockBackend *blk);
 
 void override_max_devs(BlockInterfaceType type, int max_devs);
 
-- 
2.5.0