add patch fixing resume for snapshot and hibernate with drive with iothread and a dirty bitmap

Not difficult to run into, just have a drive with iothread, take a PBS
backup and then take a snapshot or hibernate. Resuming will fail with
> qemu: qemu_mutex_unlock_impl: Operation not permitted
because of not acquiring the correct AioContext first.

Migration is not affected, because it runs in coroutine context.

Reported in the community forum:
https://forum.proxmox.com/threads/129899/

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>

debian/patches/extra/0010-migration-block-dirty-bitmap-fix-loading-bitmap-when.patch

@@ -0,0 +1,48 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Fiona Ebner <f.ebner@proxmox.com>
+Date: Fri, 28 Jul 2023 10:47:48 +0200
+Subject: [PATCH] migration/block-dirty-bitmap: fix loading bitmap when there
+ is an iothread
+
+The bdrv_create_dirty_bitmap() function (which is also called by
+bdrv_dirty_bitmap_create_successor()) uses bdrv_getlength(bs). This is
+a wrapper around a coroutine, and thus uses bdrv_poll_co(). Polling
+tries to release the AioContext which will trigger an assert() if it
+hasn't been acquired before.
+
+The issue does not happen for migration, because there we are in a
+coroutine already, so the wrapper will just call bdrv_co_getlength()
+directly without polling.
+
+Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
+---
+ migration/block-dirty-bitmap.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
+index fe73aa94b1..7eaf498439 100644
+--- a/migration/block-dirty-bitmap.c
++++ b/migration/block-dirty-bitmap.c
+@@ -805,8 +805,11 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
+                      "destination", bdrv_dirty_bitmap_name(s->bitmap));
+         return -EINVAL;
+     } else {
++        AioContext *ctx = bdrv_get_aio_context(s->bs);
++        aio_context_acquire(ctx);
+         s->bitmap = bdrv_create_dirty_bitmap(s->bs, granularity,
+                                              s->bitmap_name, &local_err);
++        aio_context_release(ctx);
+         if (!s->bitmap) {
+             error_report_err(local_err);
+             return -EINVAL;
+@@ -833,7 +836,10 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
+ 
+     bdrv_disable_dirty_bitmap(s->bitmap);
+     if (flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED) {
++        AioContext *ctx = bdrv_get_aio_context(s->bs);
++        aio_context_acquire(ctx);
+         bdrv_dirty_bitmap_create_successor(s->bitmap, &local_err);
++        aio_context_release(ctx);
+         if (local_err) {
+             error_report_err(local_err);
+             return -EINVAL;

debian/patches/pve/0035-migration-block-dirty-bitmap-migrate-other-bitmaps-e.patch

@@ -19,7 +19,7 @@ Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
  1 file changed, 1 insertion(+), 1 deletion(-)
 
 diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
-index fe73aa94b1..a6440929fa 100644
+index 7eaf498439..509f3df0a6 100644
 --- a/migration/block-dirty-bitmap.c
 +++ b/migration/block-dirty-bitmap.c
 @@ -539,7 +539,7 @@ static int add_bitmaps_to_list(DBMSaveState *s, BlockDriverState *bs,

debian/patches/pve/0044-migration-for-snapshots-hold-the-BQL-during-setup-ca.patch

@@ -67,10 +67,10 @@ index a8dfd8fefd..fa9b0b0f10 100644
       * must_precopy:
       * - must be migrated in precopy or in stopped state
 diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
-index a6440929fa..69fab3275c 100644
+index 509f3df0a6..42dc4a8d61 100644
 --- a/migration/block-dirty-bitmap.c
 +++ b/migration/block-dirty-bitmap.c
-@@ -1214,10 +1214,17 @@ static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
+@@ -1220,10 +1220,17 @@ static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
  {
      DBMSaveState *s = &((DBMState *)opaque)->save;
      SaveBitmapState *dbms = NULL;
@@ -90,7 +90,7 @@ index a6440929fa..69fab3275c 100644
          return -1;
      }
  
-@@ -1225,7 +1232,9 @@ static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
+@@ -1231,7 +1238,9 @@ static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
          send_bitmap_start(f, s, dbms);
      }
      qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);

debian/patches/series

@@ -7,6 +7,7 @@ extra/0006-lsi53c895a-disable-reentrancy-detection-for-script-R.patch
 extra/0007-bcm2835_property-disable-reentrancy-detection-for-io.patch
 extra/0008-raven-disable-reentrancy-detection-for-iomem.patch
 extra/0009-apic-disable-reentrancy-detection-for-apic-msi.patch
+extra/0010-migration-block-dirty-bitmap-fix-loading-bitmap-when.patch
 bitmap-mirror/0001-drive-mirror-add-support-for-sync-bitmap-mode-never.patch
 bitmap-mirror/0002-drive-mirror-add-support-for-conditional-and-always-.patch
 bitmap-mirror/0003-mirror-add-check-for-bitmap-mode-without-bitmap.patch