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block: Mark bdrv_filter_or_cow_bs() and callers GRAPH_RDLOCK

Browse source 
This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_filter_or_cow_bs() need to hold a reader lock for the graph because
it calls bdrv_filter_or_cow_child(), which accesses bs->file/backing.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-7-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 17:53:15 +02:00
parent f3bbc53dc5
commit 372b69f503
5 changed files with 32 additions and 16 deletions
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33
block.c
View file

@ -5435,17 +5435,6 @@ static int bdrv_replace_node_common(BlockDriverState *from,
GLOBAL_STATE_CODE();
if (detach_subchain) {
assert(bdrv_chain_contains(from, to));
assert(from != to);
for (to_cow_parent = from;
bdrv_filter_or_cow_bs(to_cow_parent) != to;
to_cow_parent = bdrv_filter_or_cow_bs(to_cow_parent))
{
;
}
}
/* Make sure that @from doesn't go away until we have successfully attached
* all of its parents to @to. */
bdrv_ref(from);
@ -5457,6 +5446,17 @@ static int bdrv_replace_node_common(BlockDriverState *from,
bdrv_graph_wrlock(to);
if (detach_subchain) {
assert(bdrv_chain_contains(from, to));
assert(from != to);
for (to_cow_parent = from;
bdrv_filter_or_cow_bs(to_cow_parent) != to;
to_cow_parent = bdrv_filter_or_cow_bs(to_cow_parent))
{
;
}
}
/*
* Do the replacement without permission update.
* Replacement may influence the permissions, we should calculate new
@ -5504,10 +5504,14 @@ int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
int bdrv_drop_filter(BlockDriverState *bs, Error **errp)
{
GLOBAL_STATE_CODE();
BlockDriverState *child_bs;
return bdrv_replace_node_common(bs, bdrv_filter_or_cow_bs(bs), true, true,
errp);
GLOBAL_STATE_CODE();
bdrv_graph_rdlock_main_loop();
child_bs = bdrv_filter_or_cow_bs(bs);
bdrv_graph_rdunlock_main_loop();
return bdrv_replace_node_common(bs, child_bs, true, true, errp);
}
/*
@ -6509,6 +6513,7 @@ bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
{
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
while (top && top != base) {
top = bdrv_filter_or_cow_bs(top);

4
block/stream.c
View file

@ -60,6 +60,8 @@ static int stream_prepare(Job *job)
Error *local_err = NULL;
int ret = 0;
GLOBAL_STATE_CODE();
/* We should drop filter at this point, as filter hold the backing chain */
bdrv_cor_filter_drop(s->cor_filter_bs);
s->cor_filter_bs = NULL;
@ -78,8 +80,10 @@ static int stream_prepare(Job *job)
bdrv_drained_begin(unfiltered_bs_cow);
}
bdrv_graph_rdlock_main_loop();
base = bdrv_filter_or_cow_bs(s->above_base);
unfiltered_base = bdrv_skip_filters(base);
bdrv_graph_rdunlock_main_loop();
if (bdrv_cow_child(unfiltered_bs)) {
const char *base_id = NULL, *base_fmt = NULL;

2
blockdev.c
View file

@ -2501,8 +2501,8 @@ void qmp_block_stream(const char *job_id, const char *device,
/*
* Check for op blockers in the whole chain between bs and base (or bottom)
*/
iter_end = bottom ? bdrv_filter_or_cow_bs(bottom_bs) : base_bs;
bdrv_graph_rdlock_main_loop();
iter_end = bottom ? bdrv_filter_or_cow_bs(bottom_bs) : base_bs;
for (iter = bs; iter && iter != iter_end;
iter = bdrv_filter_or_cow_bs(iter))
{

3
include/block/block_int-io.h
View file

@ -150,7 +150,8 @@ bdrv_filter_bs(BlockDriverState *bs)
return child_bs(bdrv_filter_child(bs));
}
static inline BlockDriverState *bdrv_filter_or_cow_bs(BlockDriverState *bs)
static inline BlockDriverState * GRAPH_RDLOCK
bdrv_filter_or_cow_bs(BlockDriverState *bs)
{
IO_CODE();
return child_bs(bdrv_filter_or_cow_child(bs));

6
nbd/server.c
View file

@ -1689,6 +1689,7 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
size_t i;
int ret;
GLOBAL_STATE_CODE();
assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
if (!nbd_server_is_running()) {
@ -1743,6 +1744,8 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
}
exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
bdrv_graph_rdlock_main_loop();
for (bitmaps = arg->bitmaps; bitmaps; bitmaps = bitmaps->next) {
exp->nr_export_bitmaps++;
}
@ -1825,9 +1828,12 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
QTAILQ_INSERT_TAIL(&exports, exp, next);
bdrv_graph_rdunlock_main_loop();
return 0;
fail:
bdrv_graph_rdunlock_main_loop();
g_free(exp->export_bitmaps);
g_free(exp->name);
g_free(exp->description);