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block: Introduce bdrv_co_change_backing_file()

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bdrv_change_backing_file() is called both inside and outside coroutine
context. This makes it difficult for it to take the graph lock
internally. It also means that driver implementations need to be able to
run outside of coroutines, too. Switch it to the usual model with a
coroutine based implementation and a co_wrapper instead. The new
function is marked GRAPH_RDLOCK.

As the co_wrapper now runs the function in the AioContext of the node
(as it should always have done), this is not GLOBAL_STATE_CODE() any
more.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-20-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2023-10-27 17:53:28 +02:00
parent 244b26d259
commit e2dd273754
7 changed files with 111 additions and 98 deletions
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3
include/block/block-global-state.h
View file

@ -142,8 +142,7 @@ bdrv_refresh_limits(BlockDriverState *bs, Transaction *tran, Error **errp);
int bdrv_commit(BlockDriverState *bs);
int GRAPH_RDLOCK bdrv_make_empty(BdrvChild *c, Error **errp);
int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
const char *backing_fmt, bool warn);
void bdrv_register(BlockDriver *bdrv);
int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
const char *backing_file_str);

8
include/block/block-io.h
View file

@ -210,6 +210,14 @@ void bdrv_round_to_subclusters(BlockDriverState *bs,
void bdrv_get_backing_filename(BlockDriverState *bs,
char *filename, int filename_size);
int coroutine_fn GRAPH_RDLOCK
bdrv_co_change_backing_file(BlockDriverState *bs, const char *backing_file,
const char *backing_fmt, bool warn);
int co_wrapper_bdrv_rdlock
bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
const char *backing_fmt, bool warn);
int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
int64_t pos, int size);

5
include/block/block_int-common.h
View file

@ -331,8 +331,9 @@ struct BlockDriver {
const char *name,
Error **errp);
int (*bdrv_change_backing_file)(BlockDriverState *bs,
const char *backing_file, const char *backing_fmt);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_change_backing_file)(
BlockDriverState *bs, const char *backing_file,
const char *backing_fmt);
/* TODO Better pass a option string/QDict/QemuOpts to add any rule? */
int (*bdrv_debug_breakpoint)(BlockDriverState *bs, const char *event,