pve-qemu-qoup/debian/patches/pve/0061-block-alloc-track-avoid-premature-break.patch
Fiona Ebner bf251437e9 update submodule and patches to QEMU 8.0.0
Many changes were necessary this time around:

* QAPI was changed to avoid redundant has_* variables, see commit
44ea9d9be3 ("qapi: Start to elide redundant has_FOO in generated C")
for details. This affected many QMP commands added by Proxmox too.

* Pending querying for migration got split into two functions, one to
estimate, one for exact value, see commit c8df4a7aef ("migration:
Split save_live_pending() into state_pending_*") for details. Relevant
for savevm-async and PBS dirty bitmap.

* Some block (driver) functions got converted to coroutines, so the
Proxmox block drivers needed to be adapted.

* Alloc track auto-detaching during PBS live restore got broken by
AioContext-related changes resulting in a deadlock. The current, hacky
method was replaced by a simpler one. Stefan apparently ran into a
problem with that when he wrote the driver, but there were
improvements in the stream job code since then and I didn't manage to
reproduce the issue. It's a separate patch "alloc-track: fix deadlock
during drop" for now, you can find the details there.

* Async snapshot-related changes:
  - The pending querying got adapted to the above-mentioned split and
  a patch is added to optimize it/make it more similar to what
  upstream code does.
  - Added initialization of the compression counters (for
    future-proofing).
  - It's necessary the hold the BQL (big QEMU lock = iothread mutex)
  during the setup phase, because block layer functions are used there
  and not doing so leads to racy, hard-to-debug crashes or hangs. It's
  necessary to change some upstream code too for this, a version of
  the patch "migration: for snapshots, hold the BQL during setup
  callbacks" is intended to be upstreamed.
  - Need to take the bdrv graph read lock before flushing.

* hmp_info_balloon was moved to a different file.

* Needed to include a new headers from time to time to still get the
correct functions.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
2023-05-22 15:09:14 +02:00

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1.5 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Fabian Ebner <f.ebner@proxmox.com>
Date: Wed, 22 Jun 2022 10:45:13 +0200
Subject: [PATCH] block: alloc-track: avoid premature break
While the bdrv_co_preadv() calls are expected to return 0 on success,
qemu_iovec_memset() will return the number of bytes set (will be
local_bytes, because the slice with that size was just initialized).
Don't break out of the loop after the branch with qemu_iovec_memset(),
because there might still be work to do. Additionally, ret is an int,
which on 64-bit platforms is too small to hold the size_t returned by
qemu_iovec_memset().
The branch seems to be difficult to reach in practice, because the
whole point of alloc-track is to be used with a backing device.
Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
---
block/alloc-track.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/alloc-track.c b/block/alloc-track.c
index 113bbd7058..b75d7c6460 100644
--- a/block/alloc-track.c
+++ b/block/alloc-track.c
@@ -175,7 +175,8 @@ static int coroutine_fn track_co_preadv(BlockDriverState *bs,
ret = bdrv_co_preadv(bs->backing, local_offset, local_bytes,
&local_qiov, flags);
} else {
- ret = qemu_iovec_memset(&local_qiov, cur_offset, 0, local_bytes);
+ qemu_iovec_memset(&local_qiov, cur_offset, 0, local_bytes);
+ ret = 0;
}
if (ret != 0) {