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[PATCH 2/8] block-backend: enable_write_cache should be atomic
From: |
Stefan Hajnoczi |
Subject: |
[PATCH 2/8] block-backend: enable_write_cache should be atomic |
Date: |
Tue, 8 Nov 2022 16:19:24 -0500 |
From: Emanuele Giuseppe Esposito <eesposit@redhat.com>
It is read from IO_CODE and written with BQL held,
so setting it as atomic should be enough.
Also remove the aiocontext lock that was sporadically
taken around the set.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220609143727.1151816-3-eesposit@redhat.com>
---
block/block-backend.c | 6 +++---
hw/block/virtio-blk.c | 4 ----
2 files changed, 3 insertions(+), 7 deletions(-)
diff --git a/block/block-backend.c b/block/block-backend.c
index c0c7d56c8d..949418cad4 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -60,7 +60,7 @@ struct BlockBackend {
* can be used to restore those options in the new BDS on insert) */
BlockBackendRootState root_state;
- bool enable_write_cache;
+ bool enable_write_cache; /* Atomic */
/* I/O stats (display with "info blockstats"). */
BlockAcctStats stats;
@@ -1939,13 +1939,13 @@ bool blk_is_sg(BlockBackend *blk)
bool blk_enable_write_cache(BlockBackend *blk)
{
IO_CODE();
- return blk->enable_write_cache;
+ return qatomic_read(&blk->enable_write_cache);
}
void blk_set_enable_write_cache(BlockBackend *blk, bool wce)
{
IO_CODE();
- blk->enable_write_cache = wce;
+ qatomic_set(&blk->enable_write_cache, wce);
}
void blk_activate(BlockBackend *blk, Error **errp)
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index cdc6fd5979..96d00103a4 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -961,9 +961,7 @@ static void virtio_blk_set_config(VirtIODevice *vdev, const
uint8_t *config)
memcpy(&blkcfg, config, s->config_size);
- aio_context_acquire(blk_get_aio_context(s->blk));
blk_set_enable_write_cache(s->blk, blkcfg.wce != 0);
- aio_context_release(blk_get_aio_context(s->blk));
}
static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features,
@@ -1031,11 +1029,9 @@ static void virtio_blk_set_status(VirtIODevice *vdev,
uint8_t status)
* s->blk would erroneously be placed in writethrough mode.
*/
if (!virtio_vdev_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE)) {
- aio_context_acquire(blk_get_aio_context(s->blk));
blk_set_enable_write_cache(s->blk,
virtio_vdev_has_feature(vdev,
VIRTIO_BLK_F_WCE));
- aio_context_release(blk_get_aio_context(s->blk));
}
}
--
2.38.1
- [PATCH 0/8] virtio-blk: remove AioContext lock, Stefan Hajnoczi, 2022/11/08
- [PATCH 2/8] block-backend: enable_write_cache should be atomic,
Stefan Hajnoczi <=
- [PATCH 1/8] virtio_queue_aio_attach_host_notifier: remove AioContext lock, Stefan Hajnoczi, 2022/11/08
- [PATCH 3/8] virtio: categorize callbacks in GS, Stefan Hajnoczi, 2022/11/08
- [PATCH 4/8] virtio-blk: mark GLOBAL_STATE_CODE functions, Stefan Hajnoczi, 2022/11/08
- [PATCH 5/8] virtio-blk: mark IO_CODE functions, Stefan Hajnoczi, 2022/11/08
- [PATCH 7/8] virtio-blk: don't acquire AioContext in virtio_blk_handle_vq(), Stefan Hajnoczi, 2022/11/08