From b36e8acc3120c641ba5f12682441964bc33b03eb Mon Sep 17 00:00:00 2001 From: Thomas Lamprecht Date: Tue, 6 Apr 2021 16:02:56 +0200 Subject: [PATCH] alloc track: acquire BS AIO context during dropping ran into this when live-restoring a backup configured for IO-threads, got the good ol': > qemu: qemu_mutex_unlock_impl: Operation not permitted error. Checking out the history of the related bdrv_backup_top_drop(*bs) method, we can see that it used to do the AIO context acquiring too, but in the backup path this was problematic and was changed to be higher up in the call path in a upstream series from Stefan[0]. That said, this is a completely different code path and it is safe to do so here. We always run from the main threads's AIO context here and we call it only indirectly once, guarded by checking for `s->drop_state == DropNone` and set `s->drop_state = DropRequested` shortly before we schedule the track_drop() in a bh. [0]: https://lists.gnu.org/archive/html/qemu-devel/2020-03/msg09139.html Signed-off-by: Thomas Lamprecht --- debian/patches/pve/0047-block-add-alloc-track-driver.patch | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/debian/patches/pve/0047-block-add-alloc-track-driver.patch b/debian/patches/pve/0047-block-add-alloc-track-driver.patch index 232ad7e..8eed42f 100644 --- a/debian/patches/pve/0047-block-add-alloc-track-driver.patch +++ b/debian/patches/pve/0047-block-add-alloc-track-driver.patch @@ -34,7 +34,7 @@ new file mode 100644 index 0000000000..b579380279 --- /dev/null +++ b/block/alloc-track.c -@@ -0,0 +1,342 @@ +@@ -0,0 +1,345 @@ +/* + * Node to allow backing images to be applied to any node. Assumes a blank + * image to begin with, only new writes are tracked as allocated, thus this @@ -313,6 +313,8 @@ index 0000000000..b579380279 + aio_bh_schedule_oneshot(qemu_get_aio_context(), track_drop, opaque); + return; + } ++ AioContext *aio_context = bdrv_get_aio_context(bs); ++ aio_context_acquire(aio_context); + + bdrv_drained_begin(bs); + @@ -324,6 +326,7 @@ index 0000000000..b579380279 + bdrv_set_backing_hd(bs, NULL, &error_abort); + bdrv_drained_end(bs); + bdrv_unref(bs); ++ aio_context_release(aio_context); +} + +static int track_change_backing_file(BlockDriverState *bs,