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qcow2: Mark qcow2_inactivate() and callers GRAPH_RDLOCK

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This adds GRAPH_RDLOCK annotations to declare that callers of
qcow2_inactivate() need to hold a reader lock for the graph because it
calls bdrv_get_device_or_node_name(), which accesses the parents list of
a node.

qcow2_do_close() is a bit strange because it is called from different
contexts. If close_data_file = true, we know that we were called from
non-coroutine main loop context (more specifically, we're coming from
qcow2_close()) and can safely drop the reader lock temporarily with
bdrv_graph_rdunlock_main_loop() and acquire the writer lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-16-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2023-09-29 16:51:50 +02:00
parent 0bb79c97fd
commit de4fed6f4e
1 changed files with 10 additions and 5 deletions
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15
block/qcow2.c
View file

@ -2737,14 +2737,12 @@ fail_nometa:
return ret;
}
static int qcow2_inactivate(BlockDriverState *bs)
static int GRAPH_RDLOCK qcow2_inactivate(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
int ret, result = 0;
Error *local_err = NULL;
assume_graph_lock(); /* FIXME */
qcow2_store_persistent_dirty_bitmaps(bs, true, &local_err);
if (local_err != NULL) {
result = -EINVAL;
@ -2774,7 +2772,8 @@ static int qcow2_inactivate(BlockDriverState *bs)
return result;
}
static void qcow2_do_close(BlockDriverState *bs, bool close_data_file)
static void coroutine_mixed_fn GRAPH_RDLOCK
qcow2_do_close(BlockDriverState *bs, bool close_data_file)
{
BDRVQcow2State *s = bs->opaque;
qemu_vfree(s->l1_table);
@ -2801,18 +2800,24 @@ static void qcow2_do_close(BlockDriverState *bs, bool close_data_file)
g_free(s->image_backing_format);
if (close_data_file && has_data_file(bs)) {
GLOBAL_STATE_CODE();
bdrv_graph_rdunlock_main_loop();
bdrv_graph_wrlock(NULL);
bdrv_unref_child(bs, s->data_file);
bdrv_graph_wrunlock();
s->data_file = NULL;
bdrv_graph_rdlock_main_loop();
}
qcow2_refcount_close(bs);
qcow2_free_snapshots(bs);
}
static void qcow2_close(BlockDriverState *bs)
static void GRAPH_UNLOCKED qcow2_close(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
qcow2_do_close(bs, true);
}