block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK

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

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: <20230929145157.45443-13-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -279,8 +279,9 @@ bool bdrv_is_read_only(BlockDriverState *bs)
     return !(bs->open_flags & BDRV_O_RDWR);
 }
 
-static int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
+static int GRAPH_RDLOCK
-                                  bool ignore_allow_rdw, Error **errp)
+bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
+                       bool ignore_allow_rdw, Error **errp)
 {
     IO_CODE();
 
@@ -319,6 +320,8 @@ int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
     int ret = 0;
     IO_CODE();
 
+    assume_graph_lock(); /* FIXME */
+
     if (!(bs->open_flags & BDRV_O_RDWR)) {
         return 0;
     }
@@ -4950,7 +4953,10 @@ bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
      * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
      * not set, or if the BDS still has copy_on_read enabled */
     read_only = !(reopen_state->flags & BDRV_O_RDWR);
+
+    bdrv_graph_rdlock_main_loop();
     ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
+    bdrv_graph_rdunlock_main_loop();
     if (local_err) {
         error_propagate(errp, local_err);
         goto error;
@@ -4984,9 +4990,11 @@ bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
     } else {
         /* It is currently mandatory to have a bdrv_reopen_prepare()
          * handler for each supported drv. */
+        bdrv_graph_rdlock_main_loop();
         error_setg(errp, "Block format '%s' used by node '%s' "
                    "does not support reopening files", drv->format_name,
                    bdrv_get_device_or_node_name(reopen_state->bs));
+        bdrv_graph_rdunlock_main_loop();
         ret = -1;
         goto error;
     }
@@ -7242,6 +7250,8 @@ bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
 {
     BdrvOpBlocker *blocker;
     GLOBAL_STATE_CODE();
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
     assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
     if (!QLIST_EMPTY(&bs->op_blockers[op])) {
         blocker = QLIST_FIRST(&bs->op_blockers[op]);

block/backup.c

@@ -374,6 +374,7 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
     assert(bs);
     assert(target);
     GLOBAL_STATE_CODE();
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
 
     /* QMP interface protects us from these cases */
     assert(sync_mode != MIRROR_SYNC_MODE_INCREMENTAL);

block/parallels.c

@@ -1363,9 +1363,12 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
         bitmap_new(DIV_ROUND_UP(s->header_size, s->bat_dirty_block));
 
     /* Disable migration until bdrv_activate method is added */
+    bdrv_graph_rdlock_main_loop();
     error_setg(&s->migration_blocker, "The Parallels format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
+    bdrv_graph_rdunlock_main_loop();
+
     ret = migrate_add_blocker(s->migration_blocker, errp);
     if (ret < 0) {
         error_setg(errp, "Migration blocker error");

block/qcow.c

@@ -301,9 +301,12 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Disable migration when qcow images are used */
+    bdrv_graph_rdlock_main_loop();
     error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
+    bdrv_graph_rdunlock_main_loop();
+
     ret = migrate_add_blocker(s->migration_blocker, errp);
     if (ret < 0) {
         error_free(s->migration_blocker);

block/qcow2-bitmap.c

@@ -166,6 +166,8 @@ static int check_constraints_on_bitmap(BlockDriverState *bs,
     int64_t len = bdrv_getlength(bs);
     int64_t bitmap_bytes;
 
+    assume_graph_lock(); /* FIXME */
+
     assert(granularity > 0);
     assert((granularity & (granularity - 1)) == 0);
 

block/qcow2.c

@@ -2737,6 +2737,8 @@ static int qcow2_inactivate(BlockDriverState *bs)
     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;
@@ -5945,6 +5947,8 @@ void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
     char *message;
     va_list ap;
 
+    assume_graph_lock(); /* FIXME */
+
     fatal = fatal && bdrv_is_writable(bs);
 
     if (s->signaled_corruption &&

block/qcow2.h

@@ -1003,10 +1003,9 @@ int coroutine_fn qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp
 bool qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,
                                           bool release_stored, Error **errp);
 int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp);
-bool coroutine_fn qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
+bool coroutine_fn GRAPH_RDLOCK
-                                                      const char *name,
+qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
-                                                      uint32_t granularity,
+                                    uint32_t granularity, Error **errp);
-                                                      Error **errp);
 int coroutine_fn qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs,
                                                          const char *name,
                                                          Error **errp);

block/quorum.c

@@ -206,7 +206,7 @@ static void quorum_report_bad(QuorumOpType type, uint64_t offset,
                                       end_sector - start_sector);
 }
 
-static void quorum_report_failure(QuorumAIOCB *acb)
+static void GRAPH_RDLOCK quorum_report_failure(QuorumAIOCB *acb)
 {
     const char *reference = bdrv_get_device_or_node_name(acb->bs);
     int64_t start_sector = acb->offset / BDRV_SECTOR_SIZE;
@@ -219,7 +219,7 @@ static void quorum_report_failure(QuorumAIOCB *acb)
 
 static int quorum_vote_error(QuorumAIOCB *acb);
 
-static bool quorum_has_too_much_io_failed(QuorumAIOCB *acb)
+static bool GRAPH_RDLOCK quorum_has_too_much_io_failed(QuorumAIOCB *acb)
 {
     BDRVQuorumState *s = acb->bs->opaque;
 

block/rbd.c

@@ -1208,6 +1208,8 @@ static int qemu_rbd_reopen_prepare(BDRVReopenState *state,
     BDRVRBDState *s = state->bs->opaque;
     int ret = 0;
 
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
     if (s->snap && state->flags & BDRV_O_RDWR) {
         error_setg(errp,
                    "Cannot change node '%s' to r/w when using RBD snapshot",

block/snapshot.c

@@ -432,6 +432,7 @@ int bdrv_snapshot_load_tmp(BlockDriverState *bs,
     BlockDriver *drv = bs->drv;
 
     GLOBAL_STATE_CODE();
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
 
     if (!drv) {
         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
@@ -641,8 +642,10 @@ int bdrv_all_goto_snapshot(const char *name,
         }
         aio_context_release(ctx);
         if (ret < 0) {
+            bdrv_graph_rdlock_main_loop();
             error_prepend(errp, "Could not load snapshot '%s' on '%s': ",
                           name, bdrv_get_device_or_node_name(bs));
+            bdrv_graph_rdunlock_main_loop();
             return -1;
         }
 

block/vdi.c

@@ -492,9 +492,12 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Disable migration when vdi images are used */
+    bdrv_graph_rdlock_main_loop();
     error_setg(&s->migration_blocker, "The vdi format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
+    bdrv_graph_rdunlock_main_loop();
+
     ret = migrate_add_blocker(s->migration_blocker, errp);
     if (ret < 0) {
         error_free(s->migration_blocker);

block/vpc.c

@@ -446,9 +446,12 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Disable migration when VHD images are used */
+    bdrv_graph_rdlock_main_loop();
     error_setg(&s->migration_blocker, "The vpc format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
+    bdrv_graph_rdunlock_main_loop();
+
     ret = migrate_add_blocker(s->migration_blocker, errp);
     if (ret < 0) {
         error_free(s->migration_blocker);

block/vvfat.c

@@ -1144,6 +1144,8 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
     QemuOpts *opts;
     int ret;
 
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
 #ifdef DEBUG
     vvv = s;
 #endif

blockjob.c

@@ -485,6 +485,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
     BlockJob *job;
     int ret;
     GLOBAL_STATE_CODE();
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
 
     if (job_id == NULL && !(flags & JOB_INTERNAL)) {
         job_id = bdrv_get_device_name(bs);

include/block/block-io.h

@@ -183,8 +183,12 @@ const char *bdrv_get_format_name(BlockDriverState *bs);
 
 bool bdrv_supports_compressed_writes(BlockDriverState *bs);
 const char *bdrv_get_node_name(const BlockDriverState *bs);
-const char *bdrv_get_device_name(const BlockDriverState *bs);
+
-const char *bdrv_get_device_or_node_name(const BlockDriverState *bs);
+const char * GRAPH_RDLOCK
+bdrv_get_device_name(const BlockDriverState *bs);
+
+const char * GRAPH_RDLOCK
+bdrv_get_device_or_node_name(const BlockDriverState *bs);
 
 int coroutine_fn GRAPH_RDLOCK
 bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);

include/block/block_int-io.h

@@ -99,7 +99,7 @@ BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
  */
 void bdrv_wakeup(BlockDriverState *bs);
 
-const char *bdrv_get_parent_name(const BlockDriverState *bs);
+const char * GRAPH_RDLOCK bdrv_get_parent_name(const BlockDriverState *bs);
 bool blk_dev_has_tray(BlockBackend *blk);
 bool blk_dev_is_tray_open(BlockBackend *blk);
 

include/block/qapi.h

@@ -33,9 +33,10 @@ BlockDeviceInfo * GRAPH_RDLOCK
 bdrv_block_device_info(BlockBackend *blk, BlockDriverState *bs,
                        bool flat, Error **errp);
 
-int bdrv_query_snapshot_info_list(BlockDriverState *bs,
+int GRAPH_RDLOCK
-                                  SnapshotInfoList **p_list,
+bdrv_query_snapshot_info_list(BlockDriverState *bs,
-                                  Error **errp);
+                              SnapshotInfoList **p_list,
+                              Error **errp);
 void GRAPH_RDLOCK
 bdrv_query_image_info(BlockDriverState *bs, ImageInfo **p_info, bool flat,
                       bool skip_implicit_filters, Error **errp);