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pve-qemu-qoup/debian/patches/pve/0047-block-copy-before-write-create-block_copy-bitmap-in-.patch
Fiona Ebner f1eed34ac7 update submodule and patches to QEMU 8.2.2 
This version includes both the AioContext lock and the block graph
lock, so there might be some deadlocks lurking. It's not possible to
disable the block graph lock like was done in QEMU 8.1, because there
are no changes like the function bdrv_schedule_unref() that require
it. QEMU 9.0 will finally get rid of the AioContext locking.

During live-restore with a VirtIO SCSI drive with iothread there is a
known racy deadlock related to the AioContext lock. Not new [1], but
not sure if more likely now. Should be fixed in QEMU 9.0.

The block graph lock comes with annotations that can be checked by
clang's TSA. This required changes to the block drivers, i.e.
alloc-track, pbs, zeroinit as well as taking the appropriate locks
in pve-backup, savevm-async, vma-reader.

Local variable shadowing is prohibited via a compiler flag now,
required slight adaptation in vma.c.

Major changes only affect alloc-track:

* It is not possible to call a generated co-wrapper like
  bdrv_get_info() while holding the block graph lock exclusively [0],
  which does happen during initialization of alloc-track when the
  backing hd is set and the refresh_limits driver callback is invoked.

  The bdrv_get_info() call to get the cluster size is moved to
  directly after opening the file child in track_open().

  The important thing is that at least the request alignment for the
  write target is used, because then the RMW cycle in bdrv_pwritev
  will gather enough data from the backing file. Partial cluster
  allocations in the target are not a fundamental issue, because the
  driver returns its allocation status based on the bitmap, so any
  other data that maps to the same cluster will still be copied later
  by a stream job (or during writes to that cluster).

* Replacing the node cannot be done in the
  track_co_change_backing_file() callback, because it is a coroutine
  and cannot hold the block graph lock exclusively. So it is moved to
  the stream job itself with the auto-remove option not having an
  effect anymore (qemu-server would always set it anyways).

  In the future, there could either be a special option for the stream
  job, or maybe the upcoming blockdev-replace QMP command can be used.

  Replacing the backing child is actually already done in the stream
  job, so no need to do it in the track_co_change_backing_file()
  callback. It also cannot be called from a coroutine. Looking at the
  implementation in the qcow2 driver, it doesn't seem to be intended
  to change the backing child itself, just update driver-internal
  state.

Other changes:

* alloc-track: Error out early when used without auto-remove. Since
  replacing the node now happens in the stream job, where the option
  cannot be read from (it's internal to the driver), it will always be
  treated as 'on'. Makes sure to have users beside qemu-server notice
  the change (should they even exist). The option can be fully dropped
  in the future while adding a version guard in qemu-server.

* alloc-track: Avoid seemingly superfluous child permission update.
  Doesn't seem necessary nowadays (maybe after commit "alloc-track:
  fix deadlock during drop" where the dropping is not rescheduled and
  delayed anymore or some upstream change). Replacing the block node
  will already update the permissions of the new node (which was the
  file child before). Should there really be some issue, instead of
  having a drop state, this could also be just based off the fact
  whether there is still a backing child.

  Dumping the cumulative (shared) permissions for the BDS with a debug
  print yields the same values after this patch and with QEMU 8.1,
  namely 3 and 5.

* PBS block driver: compile unconditionally. Proxmox VE always needs
  it and something in the build process changed to make it not enabled
  by default. Probably would need to move the build option to meson
  otherwise.

* backup: job unreferencing during cleanup needs to happen outside of
  coroutine, so it was moved to before invoking the clean

* mirror: Cherry-pick stable fix to avoid potential deadlock.

* savevm-async: migrate_init now can fail, so propagate potential
  error.

* savevm-async: compression counters are not accessible outside
  migration/ram-compress now, so drop code that prophylactically set
  it to zero.

[0]: https://lore.kernel.org/qemu-devel/220be383-3b0d-4938-b584-69ad214e5d5d@proxmox.com/
[1]: https://lore.kernel.org/qemu-devel/e13b488e-bf13-44f2-acca-e724d14f43fd@proxmox.com/

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
2024-04-26 14:14:06 +02:00

374 lines
9.3 KiB
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Raw Blame History

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Date: Thu, 11 Apr 2024 11:29:24 +0200
Subject: [PATCH] block/copy-before-write: create block_copy bitmap in filter
node
Currently block_copy creates copy_bitmap in source node. But that is in
bad relation with .independent_close=true of copy-before-write filter:
source node may be detached and removed before .bdrv_close() handler
called, which should call block_copy_state_free(), which in turn should
remove copy_bitmap.
That's all not ideal: it would be better if internal bitmap of
block-copy object is not attached to any node. But that is not possible
now.
The simplest solution is just create copy_bitmap in filter node, where
anyway two other bitmaps are created.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
block/block-copy.c | 3 +-
block/copy-before-write.c | 2 +-
include/block/block-copy.h | 1 +
tests/qemu-iotests/257.out | 112 ++++++++++++++++++-------------------
4 files changed, 60 insertions(+), 58 deletions(-)
diff --git a/block/block-copy.c b/block/block-copy.c
index 9ee3dd7ef5..8fca2c3698 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -351,6 +351,7 @@ static int64_t block_copy_calculate_cluster_size(BlockDriverState *target,
}
BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
+ BlockDriverState *copy_bitmap_bs,
const BdrvDirtyBitmap *bitmap,
Error **errp)
{
@@ -367,7 +368,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
return NULL;
}
- copy_bitmap = bdrv_create_dirty_bitmap(source->bs, cluster_size, NULL,
+ copy_bitmap = bdrv_create_dirty_bitmap(copy_bitmap_bs, cluster_size, NULL,
errp);
if (!copy_bitmap) {
return NULL;
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 2cbf6f9346..afa5f473d2 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -472,7 +472,7 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
bs->file->bs->supported_zero_flags);
- s->bcs = block_copy_state_new(bs->file, s->target, bitmap, errp);
+ s->bcs = block_copy_state_new(bs->file, s->target, bs, bitmap, errp);
if (!s->bcs) {
error_prepend(errp, "Cannot create block-copy-state: ");
ret = -EINVAL;
diff --git a/include/block/block-copy.h b/include/block/block-copy.h
index 0700953ab8..8b41643bfa 100644
--- a/include/block/block-copy.h
+++ b/include/block/block-copy.h
@@ -25,6 +25,7 @@ typedef struct BlockCopyState BlockCopyState;
typedef struct BlockCopyCallState BlockCopyCallState;
BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
+ BlockDriverState *copy_bitmap_bs,
const BdrvDirtyBitmap *bitmap,
Error **errp);
diff --git a/tests/qemu-iotests/257.out b/tests/qemu-iotests/257.out
index aa76131ca9..c33dd7f3a9 100644
--- a/tests/qemu-iotests/257.out
+++ b/tests/qemu-iotests/257.out
@@ -120,16 +120,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -596,16 +596,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -865,16 +865,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -1341,16 +1341,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -1610,16 +1610,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -2086,16 +2086,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -2355,16 +2355,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -2831,16 +2831,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -3100,16 +3100,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -3576,16 +3576,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -3845,16 +3845,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -4321,16 +4321,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -4590,16 +4590,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
@@ -5066,16 +5066,16 @@ write -P0x67 0x3fe0000 0x20000
"granularity": 65536,
"persistent": false,
"recording": false
- }
- ],
- "drive0": [
+ },
{
"busy": false,
"count": 0,
"granularity": 65536,
"persistent": false,
"recording": false
- },
+ }
+ ],
+ "drive0": [
{
"busy": false,
"count": 458752,
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