block: Mark bdrv_(un)freeze_backing_chain() and callers GRAPH_RDLOCK

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

Use the opportunity to make bdrv_is_backing_chain_frozen() static, it
has no external callers.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-10-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 17:53:18 +02:00
parent ad74751fc0
commit 9275fc72bd
7 changed files with 46 additions and 17 deletions

View File

@ -5843,8 +5843,9 @@ BlockDriverState *bdrv_find_base(BlockDriverState *bs)
* between @bs and @base is frozen. @errp is set if that's the case.
* @base must be reachable from @bs, or NULL.
*/
bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
Error **errp)
static bool GRAPH_RDLOCK
bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
Error **errp)
{
BlockDriverState *i;
BdrvChild *child;

View File

@ -48,8 +48,10 @@ static int commit_prepare(Job *job)
{
CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
bdrv_graph_rdlock_main_loop();
bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs);
s->chain_frozen = false;
bdrv_graph_rdunlock_main_loop();
/* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before
* the normal backing chain can be restored. */
@ -68,7 +70,9 @@ static void commit_abort(Job *job)
BlockDriverState *top_bs = blk_bs(s->top);
if (s->chain_frozen) {
bdrv_graph_rdlock_main_loop();
bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs);
bdrv_graph_rdunlock_main_loop();
}
/* Make sure commit_top_bs and top stay around until bdrv_replace_node() */
@ -404,7 +408,9 @@ void commit_start(const char *job_id, BlockDriverState *bs,
fail:
if (s->chain_frozen) {
bdrv_graph_rdlock_main_loop();
bdrv_unfreeze_backing_chain(commit_top_bs, base);
bdrv_graph_rdunlock_main_loop();
}
if (s->base) {
blk_unref(s->base);

View File

@ -35,8 +35,8 @@ typedef struct BDRVStateCOR {
} BDRVStateCOR;
static int cor_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
static int GRAPH_UNLOCKED
cor_open(BlockDriverState *bs, QDict *options, int flags, Error **errp)
{
BlockDriverState *bottom_bs = NULL;
BDRVStateCOR *state = bs->opaque;
@ -44,6 +44,8 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags,
const char *bottom_node = qdict_get_try_str(options, "bottom");
int ret;
GLOBAL_STATE_CODE();
ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
if (ret < 0) {
return ret;
@ -59,6 +61,8 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags,
bs->file->bs->supported_zero_flags);
if (bottom_node) {
GRAPH_RDLOCK_GUARD_MAINLOOP();
bottom_bs = bdrv_find_node(bottom_node);
if (!bottom_bs) {
error_setg(errp, "Bottom node '%s' not found", bottom_node);
@ -227,13 +231,17 @@ cor_co_lock_medium(BlockDriverState *bs, bool locked)
}
static void cor_close(BlockDriverState *bs)
static void GRAPH_UNLOCKED cor_close(BlockDriverState *bs)
{
BDRVStateCOR *s = bs->opaque;
GLOBAL_STATE_CODE();
if (s->chain_frozen) {
bdrv_graph_rdlock_main_loop();
s->chain_frozen = false;
bdrv_unfreeze_backing_chain(bs, s->bottom_bs);
bdrv_graph_rdunlock_main_loop();
}
bdrv_unref(s->bottom_bs);
@ -263,12 +271,15 @@ static BlockDriver bdrv_copy_on_read = {
};
void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs)
void no_coroutine_fn bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs)
{
BDRVStateCOR *s = cor_filter_bs->opaque;
GLOBAL_STATE_CODE();
/* unfreeze, as otherwise bdrv_replace_node() will fail */
if (s->chain_frozen) {
GRAPH_RDLOCK_GUARD_MAINLOOP();
s->chain_frozen = false;
bdrv_unfreeze_backing_chain(cor_filter_bs, s->bottom_bs);
}

View File

@ -27,6 +27,7 @@
#include "block/block_int.h"
void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs);
void no_coroutine_fn GRAPH_UNLOCKED
bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs);
#endif /* BLOCK_COPY_ON_READ_H */

View File

@ -678,6 +678,7 @@ static int mirror_exit_common(Job *job)
s->prepared = true;
aio_context_acquire(qemu_get_aio_context());
bdrv_graph_rdlock_main_loop();
mirror_top_bs = s->mirror_top_bs;
bs_opaque = mirror_top_bs->opaque;
@ -696,6 +697,8 @@ static int mirror_exit_common(Job *job)
bdrv_ref(mirror_top_bs);
bdrv_ref(target_bs);
bdrv_graph_rdunlock_main_loop();
/*
* Remove target parent that still uses BLK_PERM_WRITE/RESIZE before
* inserting target_bs at s->to_replace, where we might not be able to get

View File

@ -266,6 +266,8 @@ void stream_start(const char *job_id, BlockDriverState *bs,
assert(!(base && bottom));
assert(!(backing_file_str && bottom));
bdrv_graph_rdlock_main_loop();
if (bottom) {
/*
* New simple interface. The code is written in terms of old interface
@ -278,13 +280,11 @@ void stream_start(const char *job_id, BlockDriverState *bs,
assert(!bottom->drv->is_filter);
base_overlay = above_base = bottom;
} else {
GRAPH_RDLOCK_GUARD_MAINLOOP();
base_overlay = bdrv_find_overlay(bs, base);
if (!base_overlay) {
error_setg(errp, "'%s' is not in the backing chain of '%s'",
base->node_name, bs->node_name);
return;
goto out_rdlock;
}
/*
@ -306,7 +306,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
if (bs_read_only) {
/* Hold the chain during reopen */
if (bdrv_freeze_backing_chain(bs, above_base, errp) < 0) {
return;
goto out_rdlock;
}
ret = bdrv_reopen_set_read_only(bs, false, errp);
@ -315,10 +315,12 @@ void stream_start(const char *job_id, BlockDriverState *bs,
bdrv_unfreeze_backing_chain(bs, above_base);
if (ret < 0) {
return;
goto out_rdlock;
}
}
bdrv_graph_rdunlock_main_loop();
opts = qdict_new();
qdict_put_str(opts, "driver", "copy-on-read");
@ -413,4 +415,8 @@ fail:
if (bs_read_only) {
bdrv_reopen_set_read_only(bs, true, NULL);
}
return;
out_rdlock:
bdrv_graph_rdunlock_main_loop();
}

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@ -149,11 +149,12 @@ BlockDriverState * GRAPH_RDLOCK
bdrv_find_overlay(BlockDriverState *active, BlockDriverState *bs);
BlockDriverState * GRAPH_RDLOCK bdrv_find_base(BlockDriverState *bs);
bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
Error **errp);
int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
Error **errp);
void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base);
int GRAPH_RDLOCK
bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
Error **errp);
void GRAPH_RDLOCK
bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base);
/*
* The units of offset and total_work_size may be chosen arbitrarily by the