block: Mark bdrv_co_pdiscard() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_co_pdiscard() need to hold a reader lock for the graph.

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: <20230203152202.49054-9-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

3 files changed, 13 insertions, 9 deletions

diff --git a/include/block/block-io.h b/include/block/block-io.h
index 7e96506138..627061fd5f 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -103,8 +103,9 @@ bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf);
 /* Ensure contents are flushed to disk.  */
 int coroutine_fn GRAPH_RDLOCK bdrv_co_flush(BlockDriverState *bs);
 
-int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset,
-                                  int64_t bytes);
+int coroutine_fn GRAPH_RDLOCK bdrv_co_pdiscard(BdrvChild *child, int64_t offset,
+                                               int64_t bytes);
+
 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
 int bdrv_block_status(BlockDriverState *bs, int64_t offset,
                       int64_t bytes, int64_t *pnum, int64_t *map,
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 51eaabd9d1..c52190abdb 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -479,8 +479,9 @@ struct BlockDriver {
         BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque);
     BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_flush)(
         BlockDriverState *bs, BlockCompletionFunc *cb, void *opaque);
-    BlockAIOCB *(*bdrv_aio_pdiscard)(BlockDriverState *bs,
-        int64_t offset, int bytes,
+
+    BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_pdiscard)(
+        BlockDriverState *bs, int64_t offset, int bytes,
         BlockCompletionFunc *cb, void *opaque);
 
     int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
@@ -543,8 +544,9 @@ struct BlockDriver {
      */
     int coroutine_fn (*bdrv_co_pwrite_zeroes)(BlockDriverState *bs,
         int64_t offset, int64_t bytes, BdrvRequestFlags flags);
-    int coroutine_fn (*bdrv_co_pdiscard)(BlockDriverState *bs,
-        int64_t offset, int64_t bytes);
+
+    int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard)(
+        BlockDriverState *bs, int64_t offset, int64_t bytes);
 
     /*
      * Map [offset, offset + nbytes) range onto a child of @bs to copy from,
@@ -632,8 +634,9 @@ struct BlockDriver {
     int coroutine_fn (*bdrv_co_snapshot_block_status)(BlockDriverState *bs,
         bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum,
         int64_t *map, BlockDriverState **file);
-    int coroutine_fn (*bdrv_co_pdiscard_snapshot)(BlockDriverState *bs,
-        int64_t offset, int64_t bytes);
+
+    int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard_snapshot)(
+        BlockDriverState *bs, int64_t offset, int64_t bytes);
 
     /*
      * Invalidate any cached meta-data.
diff --git a/include/block/block_int-io.h b/include/block/block_int-io.h
index 4430bf4c4a..4bb6ccaa34 100644
--- a/include/block/block_int-io.h
+++ b/include/block/block_int-io.h
@@ -40,7 +40,7 @@ int coroutine_fn bdrv_co_preadv_snapshot(BdrvChild *child,
 int coroutine_fn bdrv_co_snapshot_block_status(BlockDriverState *bs,
     bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum,
     int64_t *map, BlockDriverState **file);
-int coroutine_fn bdrv_co_pdiscard_snapshot(BlockDriverState *bs,
+int coroutine_fn GRAPH_RDLOCK bdrv_co_pdiscard_snapshot(BlockDriverState *bs,
     int64_t offset, int64_t bytes);