RE: [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

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