Signed-off-by: Emanuele Giuseppe Esposito <eespo...@redhat.com> --- include/block/block_int-common.h | 65 ++++++++++++++++++++++---------- 1 file changed, 46 insertions(+), 19 deletions(-)
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 184cfab2d6..a6ea824b64 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -798,12 +798,31 @@ struct BdrvChildClass { */ bool parent_is_bds; + /* + * Global state (GS) API. These functions run under the BQL lock. + * + * If a function modifies the graph, it also uses drain and/or + * aio_context_acquire/release to be sure it has unique access. + * aio_context locking is needed together with BQL because of + * the thread-safe I/O API that concurrently runs and accesses + * the graph without the BQL. + * + * It is important to note that not all of these functions are + * necessarily limited to running under the BQL, but they would + * require additional auditing and may small thread-safety changes + * to move them into the I/O API. Often it's not worth doing that + * work since the APIs are only used with the BQL held at the + * moment, so they have been placed in the GS API (for now). + * + * All callers that use these function pointers must + * use this assertion: + * g_assert(qemu_in_main_thread()); + * to catch when they are accidentally called without the BQL. + */ void (*inherit_options)(BdrvChildRole role, bool parent_is_format, int *child_flags, QDict *child_options, int parent_flags, QDict *parent_options); - void (*change_media)(BdrvChild *child, bool load); - void (*resize)(BdrvChild *child); /* * Returns a name that is supposedly more useful for human users than the @@ -820,6 +839,31 @@ struct BdrvChildClass { */ char *(*get_parent_desc)(BdrvChild *child); + void (*attach)(BdrvChild *child); + void (*detach)(BdrvChild *child); + + /* + * Notifies the parent that the filename of its child has changed (e.g. + * because the direct child was removed from the backing chain), so that it + * can update its reference. + */ + int (*update_filename)(BdrvChild *child, BlockDriverState *new_base, + const char *filename, Error **errp); + + bool (*can_set_aio_ctx)(BdrvChild *child, AioContext *ctx, + GSList **ignore, Error **errp); + void (*set_aio_ctx)(BdrvChild *child, AioContext *ctx, GSList **ignore); + + AioContext *(*get_parent_aio_context)(BdrvChild *child); + + /* + * I/O API functions. These functions are thread-safe, and therefore + * can run in any thread as long as they have called + * aio_context_acquire/release(). + */ + + void (*resize)(BdrvChild *child); + /* * If this pair of functions is implemented, the parent doesn't issue new * requests after returning from .drained_begin() until .drained_end() is @@ -852,23 +896,6 @@ struct BdrvChildClass { */ void (*activate)(BdrvChild *child, Error **errp); int (*inactivate)(BdrvChild *child); - - void (*attach)(BdrvChild *child); - void (*detach)(BdrvChild *child); - - /* - * Notifies the parent that the filename of its child has changed (e.g. - * because the direct child was removed from the backing chain), so that it - * can update its reference. - */ - int (*update_filename)(BdrvChild *child, BlockDriverState *new_base, - const char *filename, Error **errp); - - bool (*can_set_aio_ctx)(BdrvChild *child, AioContext *ctx, - GSList **ignore, Error **errp); - void (*set_aio_ctx)(BdrvChild *child, AioContext *ctx, GSList **ignore); - - AioContext *(*get_parent_aio_context)(BdrvChild *child); }; extern const BdrvChildClass child_of_bds; -- 2.27.0