[PATCH] block: Don't inactivate bs if it is aleady inactive

[Tuguoyi <tu.guoyi@h3c.com>]

The following steps will cause qemu assertion failure:
- pause vm
- save memory snapshot into local file through fd migration
- do the above operation again will cause qemu assertion failure

The backtrace looks like:
#0  0x00007fbf958c5c37 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007fbf958c9028 in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007fbf958bebf6 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3  0x00007fbf958beca2 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
#4  0x000055ca8decd39d in bdrv_inactivate_recurse (bs=0x55ca90c80400) at /build/qemu-5.0/block.c:5724
#5  0x000055ca8dece967 in bdrv_inactivate_all () at /build//qemu-5.0/block.c:5792
#6  0x000055ca8de5539d in qemu_savevm_state_complete_precopy_non_iterable (inactivate_disks=true, in_postcopy=false, f=0x55ca907044b0)
    at /build/qemu-5.0/migration/savevm.c:1401
#7  qemu_savevm_state_complete_precopy (f=0x55ca907044b0, iterable_only=iterable_only@entry=false, inactivate_disks=inactivate_disks@entry=true)
    at /build/qemu-5.0/migration/savevm.c:1453
#8  0x000055ca8de4f581 in migration_completion (s=0x55ca8f64d9f0) at /build/qemu-5.0/migration/migration.c:2941
#9  migration_iteration_run (s=0x55ca8f64d9f0) at /build/qemu-5.0/migration/migration.c:3295
#10 migration_thread (opaque=opaque@entry=0x55ca8f64d9f0) at /build/qemu-5.0/migration/migration.c:3459
#11 0x000055ca8dfc6716 in qemu_thread_start (args=<optimized out>) at /build/qemu-5.0/util/qemu-thread-posix.c:519
#12 0x00007fbf95c5f184 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#13 0x00007fbf9598cbed in clone () from /lib/x86_64-linux-gnu/libc.so.6

When the first migration completes, bs->open_flags will set BDRV_O_INACTIVE flag
by bdrv_inactivate_recurse(), and during the second migration the
bdrv_inactivate_recurse assert that the bs->open_flags is already BDRV_O_INACTIVE
enabled which cause crash.

This patch just make the bdrv_inactivate_all() to don't inactivate the bs if it is
already inactive

Signed-off-by: Tuguoyi <tu.guoyi@h3c.com>
---
 block.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/block.c b/block.c
index f1cedac..02361e1 100644
--- a/block.c
+++ b/block.c
@@ -5938,6 +5938,11 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs)
     return 0;
 }
 
+static bool bdrv_is_inactive(BlockDriverState *bs)
+{
+    return bs->open_flags & BDRV_O_INACTIVE;
+}
+
 int bdrv_inactivate_all(void)
 {
     BlockDriverState *bs = NULL;
@@ -5958,7 +5963,7 @@ int bdrv_inactivate_all(void)
         /* Nodes with BDS parents are covered by recursion from the last
          * parent that gets inactivated. Don't inactivate them a second
          * time if that has already happened. */
-        if (bdrv_has_bds_parent(bs, false)) {
+        if (bdrv_has_bds_parent(bs, false) || bdrv_is_inactive(bs)) {
             continue;
         }
         ret = bdrv_inactivate_recurse(bs);
-- 
2.7.4


--
Best regards,
Guoyi