[Qemu-devel] [patch 2/5] blockdev: add refcount to DriveInfo

[Marcelo Tosatti <mtosatti@redhat.com>]

[-- Attachment #1: 01-driveinfo-ref --]
[-- Type: text/plain, Size: 2628 bytes --]

The host part of a block device can be deleted with in progress
block migration.

To fix this, add a reference count to DriveInfo, freeing resources
on last reference.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>

Index: qemu/blockdev.c
===================================================================
--- qemu.orig/blockdev.c
+++ qemu/blockdev.c
@@ -40,7 +40,7 @@ void blockdev_auto_del(BlockDriverState 
     DriveInfo *dinfo = drive_get_by_blockdev(bs);
 
     if (dinfo && dinfo->auto_del) {
-        drive_uninit(dinfo);
+        drive_put_ref(dinfo);
     }
 }
 
@@ -110,7 +110,7 @@ static void bdrv_format_print(void *opaq
     fprintf(stderr, " %s", name);
 }
 
-void drive_uninit(DriveInfo *dinfo)
+static void drive_uninit(DriveInfo *dinfo)
 {
     qemu_opts_del(dinfo->opts);
     bdrv_delete(dinfo->bdrv);
@@ -118,6 +118,19 @@ void drive_uninit(DriveInfo *dinfo)
     qemu_free(dinfo);
 }
 
+void drive_put_ref(DriveInfo *dinfo)
+{
+    assert(dinfo->refcount);
+    if (--dinfo->refcount == 0) {
+        drive_uninit(dinfo);
+    }
+}
+
+void drive_get_ref(DriveInfo *dinfo)
+{
+    dinfo->refcount++;
+}
+
 static int parse_block_error_action(const char *buf, int is_read)
 {
     if (!strcmp(buf, "ignore")) {
@@ -421,6 +434,7 @@ DriveInfo *drive_init(QemuOpts *opts, in
     dinfo->bus = bus_id;
     dinfo->unit = unit_id;
     dinfo->opts = opts;
+    dinfo->refcount = 1;
     if (serial)
         strncpy(dinfo->serial, serial, sizeof(dinfo->serial) - 1);
     QTAILQ_INSERT_TAIL(&drives, dinfo, next);
Index: qemu/blockdev.h
===================================================================
--- qemu.orig/blockdev.h
+++ qemu/blockdev.h
@@ -29,6 +29,7 @@ struct DriveInfo {
     QemuOpts *opts;
     char serial[BLOCK_SERIAL_STRLEN + 1];
     QTAILQ_ENTRY(DriveInfo) next;
+    int refcount;
 };
 
 #define MAX_IDE_DEVS	2
@@ -36,7 +37,8 @@ struct DriveInfo {
 
 DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit);
 int drive_get_max_bus(BlockInterfaceType type);
-void drive_uninit(DriveInfo *dinfo);
+void drive_get_ref(DriveInfo *dinfo);
+void drive_put_ref(DriveInfo *dinfo);
 DriveInfo *drive_get_by_blockdev(BlockDriverState *bs);
 
 QemuOpts *drive_add(const char *file, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
Index: qemu/hw/pci-hotplug.c
===================================================================
--- qemu.orig/hw/pci-hotplug.c
+++ qemu/hw/pci-hotplug.c
@@ -146,7 +146,7 @@ void drive_hot_add(Monitor *mon, const Q
 
 err:
     if (dinfo)
-        drive_uninit(dinfo);
+        drive_put_ref(dinfo);
     return;
 }