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block: Mark bdrv_cow_child() and callers GRAPH_RDLOCK 

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_cow_child() need to hold a reader lock for the graph because it
accesses bs->backing.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-13-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
master
Kevin Wolf 2023-10-27 17:53:21 +02:00
parent ec82cc41a7
commit 78a9c76eef
3 changed files with 12 additions and 6 deletions
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2
block/stream.c
View File

@ -90,7 +90,7 @@ static int stream_prepare(Job *job)
unfiltered_base = bdrv_skip_filters(base);
bdrv_graph_rdunlock_main_loop();
if (bdrv_cow_child(unfiltered_bs)) {
if (unfiltered_bs_cow) {
const char *base_id = NULL, *base_fmt = NULL;
if (unfiltered_base) {
base_id = s->backing_file_str ?: unfiltered_base->filename;

5
include/block/block_int-io.h
View File

@ -130,14 +130,15 @@ bdrv_co_refresh_total_sectors(BlockDriverState *bs, int64_t hint);
int co_wrapper_mixed_bdrv_rdlock
bdrv_refresh_total_sectors(BlockDriverState *bs, int64_t hint);
BdrvChild *bdrv_cow_child(BlockDriverState *bs);
BdrvChild * GRAPH_RDLOCK bdrv_cow_child(BlockDriverState *bs);
BdrvChild * GRAPH_RDLOCK bdrv_filter_child(BlockDriverState *bs);
BdrvChild * GRAPH_RDLOCK bdrv_filter_or_cow_child(BlockDriverState *bs);
BdrvChild * GRAPH_RDLOCK bdrv_primary_child(BlockDriverState *bs);
BlockDriverState * GRAPH_RDLOCK bdrv_skip_filters(BlockDriverState *bs);
BlockDriverState * GRAPH_RDLOCK bdrv_backing_chain_next(BlockDriverState *bs);
static inline BlockDriverState *bdrv_cow_bs(BlockDriverState *bs)
static inline BlockDriverState * GRAPH_RDLOCK
bdrv_cow_bs(BlockDriverState *bs)
{
IO_CODE();
return child_bs(bdrv_cow_child(bs));

11
qemu-img.c
View File

@ -3541,7 +3541,7 @@ static int img_rebase(int argc, char **argv)
uint8_t *buf_old = NULL;
uint8_t *buf_new = NULL;
BlockDriverState *bs = NULL, *prefix_chain_bs = NULL;
BlockDriverState *unfiltered_bs;
BlockDriverState *unfiltered_bs, *unfiltered_bs_cow;
BlockDriverInfo bdi = {0};
char *filename;
const char *fmt, *cache, *src_cache, *out_basefmt, *out_baseimg;
@ -3675,6 +3675,7 @@ static int img_rebase(int argc, char **argv)
bdrv_graph_rdlock_main_loop();
unfiltered_bs = bdrv_skip_filters(bs);
unfiltered_bs_cow = bdrv_cow_bs(unfiltered_bs);
bdrv_graph_rdunlock_main_loop();
if (compress && !block_driver_can_compress(unfiltered_bs->drv)) {
@ -3710,7 +3711,11 @@ static int img_rebase(int argc, char **argv)
/* For safe rebasing we need to compare old and new backing file */
if (!unsafe) {
QDict *options = NULL;
BlockDriverState *base_bs = bdrv_cow_bs(unfiltered_bs);
BlockDriverState *base_bs;
bdrv_graph_rdlock_main_loop();
base_bs = bdrv_cow_bs(unfiltered_bs);
bdrv_graph_rdunlock_main_loop();
if (base_bs) {
blk_old_backing = blk_new(qemu_get_aio_context(),
@ -3876,7 +3881,7 @@ static int img_rebase(int argc, char **argv)
* If cluster wasn't changed since prefix_chain, we don't need
* to take action
*/
ret = bdrv_is_allocated_above(bdrv_cow_bs(unfiltered_bs),
ret = bdrv_is_allocated_above(unfiltered_bs_cow,
prefix_chain_bs, false,
offset, n, &n);
if (ret < 0) {