block: Mark read/write in block/io.c GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_driver_*() need to hold a reader lock for the graph. It doesn't add
the annotation to public functions yet.

For some places, we know that they will hold the lock, but we don't have
the GRAPH_RDLOCK annotations yet. In this case, add assume_graph_lock()
with a FIXME comment. These places will be removed once everything is
properly annotated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230203152202.49054-11-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 20 insertions, 17 deletions

diff --git a/block/qcow2.c b/block/qcow2.c
index 89c3edbd61..8f5ad75984 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2137,9 +2137,8 @@ static int coroutine_fn qcow2_co_block_status(BlockDriverState *bs,
     return status;
 }
 
-static coroutine_fn int qcow2_handle_l2meta(BlockDriverState *bs,
-                                            QCowL2Meta **pl2meta,
-                                            bool link_l2)
+static int coroutine_fn GRAPH_RDLOCK
+qcow2_handle_l2meta(BlockDriverState *bs, QCowL2Meta **pl2meta, bool link_l2)
 {
     int ret = 0;
     QCowL2Meta *l2meta = *pl2meta;
@@ -2617,9 +2616,10 @@ static coroutine_fn GRAPH_RDLOCK int qcow2_co_pwritev_task_entry(AioTask *task)
                                  t->l2meta);
 }
 
-static coroutine_fn int qcow2_co_pwritev_part(
-        BlockDriverState *bs, int64_t offset, int64_t bytes,
-        QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags)
+static int coroutine_fn GRAPH_RDLOCK
+qcow2_co_pwritev_part(BlockDriverState *bs, int64_t offset, int64_t bytes,
+                      QEMUIOVector *qiov, size_t qiov_offset,
+                      BdrvRequestFlags flags)
 {
     BDRVQcow2State *s = bs->opaque;
     int offset_in_cluster;
@@ -2629,8 +2629,6 @@ static coroutine_fn int qcow2_co_pwritev_part(
     QCowL2Meta *l2meta = NULL;
     AioTaskPool *aio = NULL;
 
-    assume_graph_lock(); /* FIXME */
-
     trace_qcow2_writev_start_req(qemu_coroutine_self(), offset, bytes);
 
     while (bytes != 0 && aio_task_pool_status(aio) == 0) {
@@ -4160,6 +4158,7 @@ qcow2_co_copy_range_to(BlockDriverState *bs,
     uint64_t host_offset;
     QCowL2Meta *l2meta = NULL;
 
+    assume_graph_lock(); /* FIXME */
     assert(!bs->encrypted);
 
     qemu_co_mutex_lock(&s->lock);
@@ -4591,7 +4590,7 @@ fail:
     return ret;
 }
 
-static coroutine_fn int
+static int coroutine_fn GRAPH_RDLOCK
 qcow2_co_pwritev_compressed_task(BlockDriverState *bs,
                                  uint64_t offset, uint64_t bytes,
                                  QEMUIOVector *qiov, size_t qiov_offset)
@@ -4655,7 +4654,13 @@ fail:
     return ret;
 }
 
-static coroutine_fn int qcow2_co_pwritev_compressed_task_entry(AioTask *task)
+/*
+ * This function can count as GRAPH_RDLOCK because
+ * qcow2_co_pwritev_compressed_part() holds the graph lock and keeps it until
+ * this coroutine has terminated.
+ */
+static int coroutine_fn GRAPH_RDLOCK
+qcow2_co_pwritev_compressed_task_entry(AioTask *task)
 {
     Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
 
@@ -4669,7 +4674,7 @@ static coroutine_fn int qcow2_co_pwritev_compressed_task_entry(AioTask *task)
  * XXX: put compressed sectors first, then all the cluster aligned
  * tables to avoid losing bytes in alignment
  */
-static coroutine_fn int
+static int coroutine_fn GRAPH_RDLOCK
 qcow2_co_pwritev_compressed_part(BlockDriverState *bs,
                                  int64_t offset, int64_t bytes,
                                  QEMUIOVector *qiov, size_t qiov_offset)
@@ -4678,8 +4683,6 @@ qcow2_co_pwritev_compressed_part(BlockDriverState *bs,
     AioTaskPool *aio = NULL;
     int ret = 0;
 
-    assume_graph_lock(); /* FIXME */
-
     if (has_data_file(bs)) {
         return -ENOTSUP;
     }
@@ -5296,8 +5299,8 @@ static int64_t qcow2_check_vmstate_request(BlockDriverState *bs,
     return pos;
 }
 
-static coroutine_fn int qcow2_co_save_vmstate(BlockDriverState *bs,
-                                              QEMUIOVector *qiov, int64_t pos)
+static int coroutine_fn GRAPH_RDLOCK
+qcow2_co_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
 {
     int64_t offset = qcow2_check_vmstate_request(bs, qiov, pos);
     if (offset < 0) {
@@ -5308,8 +5311,8 @@ static coroutine_fn int qcow2_co_save_vmstate(BlockDriverState *bs,
     return bs->drv->bdrv_co_pwritev_part(bs, offset, qiov->size, qiov, 0, 0);
 }
 
-static coroutine_fn int qcow2_co_load_vmstate(BlockDriverState *bs,
-                                              QEMUIOVector *qiov, int64_t pos)
+static int coroutine_fn GRAPH_RDLOCK
+qcow2_co_load_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
 {
     int64_t offset = qcow2_check_vmstate_request(bs, qiov, pos);
     if (offset < 0) {