This simplifies the code somewhat, especially when dropping whole
backing file subchains.
The exception is the mirroring code that does adventurous things with
bdrv_swap() and in order to keep it working, I had to duplicate most of
bdrv_set_backing_hd() locally. We'll get rid again of this ugliness
shortly.
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
block.c | 35 ++++++++++++++---------------------
block/mirror.c | 17 ++++++++++++-----
block/stream.c | 21 ---------------------
block/vvfat.c | 6 +++++-
include/block/block.h | 1 +
5 files changed, 32 insertions(+), 48 deletions(-)
diff --git a/block.c b/block.c
index fb94567..743f82e 100644
--- a/block.c
+++ b/block.c
@@ -1094,7 +1094,7 @@ static BdrvChild *bdrv_attach_child(BlockDriverState
*parent_bs,
return child;
}
-static void bdrv_detach_child(BdrvChild *child)
+void bdrv_detach_child(BdrvChild *child)
{
QLIST_REMOVE(child, next);
g_free(child);
@@ -1112,13 +1112,20 @@ void bdrv_unref_child(BlockDriverState *parent,
BdrvChild *child)
bdrv_unref(child_bs);
}
+/*
+ * Sets the backing file link of a BDS. A new reference is created; callers
+ * which don't need their own reference any more must call bdrv_unref().
+ */
void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
{
+ if (backing_hd) {
+ bdrv_ref(backing_hd);
+ }
if (bs->backing) {
assert(bs->backing_blocker);
bdrv_op_unblock_all(bs->backing->bs, bs->backing_blocker);
- bdrv_detach_child(bs->backing);
+ bdrv_unref_child(bs, bs->backing);
} else if (backing_hd) {
error_setg(&bs->backing_blocker,
"node is used as backing hd of '%s'",
@@ -1214,7 +1221,10 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict
*options, Error **errp)
goto free_exit;
}
+ /* Hook up the backing file link; drop our reference, bs owns the
+ * backing_hd reference now */
bdrv_set_backing_hd(bs, backing_hd);
+ bdrv_unref(backing_hd);
free_exit:
g_free(backing_filename);
@@ -1884,11 +1894,7 @@ void bdrv_close(BlockDriverState *bs)
bs->drv->bdrv_close(bs);
- if (bs->backing) {
- BlockDriverState *backing_hd = bs->backing->bs;
- bdrv_set_backing_hd(bs, NULL);
- bdrv_unref(backing_hd);
- }
+ bdrv_set_backing_hd(bs, NULL);
if (bs->file != NULL) {
bdrv_unref(bs->file->bs);
@@ -2427,12 +2433,9 @@ int bdrv_drop_intermediate(BlockDriverState *active,
BlockDriverState *top,
BlockDriverState *intermediate;
BlockDriverState *base_bs = NULL;
BlockDriverState *new_top_bs = NULL;
- BlkIntermediateStates *intermediate_state, *next;
+ BlkIntermediateStates *intermediate_state;
int ret = -EIO;
- QSIMPLEQ_HEAD(states_to_delete, BlkIntermediateStates) states_to_delete;
- QSIMPLEQ_INIT(&states_to_delete);
-
if (!top->drv || !base->drv) {
goto exit;
}
@@ -2459,7 +2462,6 @@ int bdrv_drop_intermediate(BlockDriverState *active,
BlockDriverState *top,
while (intermediate) {
intermediate_state = g_new0(BlkIntermediateStates, 1);
intermediate_state->bs = intermediate;
- QSIMPLEQ_INSERT_TAIL(&states_to_delete, intermediate_state, entry);
if (backing_bs(intermediate) == base) {
base_bs = backing_bs(intermediate);
@@ -2482,17 +2484,8 @@ int bdrv_drop_intermediate(BlockDriverState *active,
BlockDriverState *top,
}
bdrv_set_backing_hd(new_top_bs, base_bs);
- QSIMPLEQ_FOREACH_SAFE(intermediate_state, &states_to_delete, entry, next) {
- /* so that bdrv_close() does not recursively close the chain */
- bdrv_set_backing_hd(intermediate_state->bs, NULL);
- bdrv_unref(intermediate_state->bs);
- }
ret = 0;
-
exit:
- QSIMPLEQ_FOREACH_SAFE(intermediate_state, &states_to_delete, entry, next) {
- g_free(intermediate_state);
- }
return ret;
}
diff --git a/block/mirror.c b/block/mirror.c
index 259e11a..571da27 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -370,11 +370,18 @@ static void mirror_exit(BlockJob *job, void *opaque)
bdrv_swap(s->target, to_replace);
if (s->common.driver->job_type == BLOCK_JOB_TYPE_COMMIT) {
/* drop the bs loop chain formed by the swap: break the loop then
- * trigger the unref from the top one */
- BlockDriverState *p = s->base->backing
- ? s->base->backing->bs : NULL;
- bdrv_set_backing_hd(s->base, NULL);
- bdrv_unref(p);
+ * trigger the unref */
+ /* FIXME This duplicates bdrv_set_backing_hd(), except for the
+ * actual detach/unref so that the loop can be broken. When
+ * bdrv_swap() gets replaced, this will become sane again. */
+ BlockDriverState *backing = s->base->backing->bs;
+ assert(s->base->backing_blocker);
+ bdrv_op_unblock_all(s->base->backing->bs,
s->base->backing_blocker);
+ error_free(s->base->backing_blocker);
+ s->base->backing_blocker = NULL;
+ bdrv_detach_child(s->base->backing);
+ s->base->backing = NULL;
+ bdrv_unref(backing);
}
}
if (s->to_replace) {
diff --git a/block/stream.c b/block/stream.c
index ece7b58..c20aedb 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -55,28 +55,7 @@ static int coroutine_fn stream_populate(BlockDriverState *bs,
static void close_unused_images(BlockDriverState *top, BlockDriverState *base,
const char *base_id)
{
- BlockDriverState *intermediate;
- intermediate = top->backing ? top->backing->bs : NULL;
-
- /* Must assign before bdrv_delete() to prevent traversing dangling pointer
- * while we delete backing image instances.
- */
bdrv_set_backing_hd(top, base);
-
- while (intermediate) {
- BlockDriverState *unused;
-
- /* reached base */
- if (intermediate == base) {
- break;
- }
-
- unused = intermediate;
- intermediate = intermediate->backing ? intermediate->backing->bs :
NULL;
- bdrv_set_backing_hd(unused, NULL);
- bdrv_unref(unused);
- }
-
bdrv_refresh_limits(top, NULL);
}
diff --git a/block/vvfat.c b/block/vvfat.c
index 7c4b0f5..b41055a 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -2923,6 +2923,7 @@ static BlockDriver vvfat_write_target = {
static int enable_write_target(BDRVVVFATState *s, Error **errp)
{
BlockDriver *bdrv_qcow = NULL;
+ BlockDriverState *backing;
QemuOpts *opts = NULL;
int ret;
int size = sector2cluster(s, s->sector_count);
@@ -2971,7 +2972,10 @@ static int enable_write_target(BDRVVVFATState *s, Error
**errp)
unlink(s->qcow_filename);
#endif
- bdrv_set_backing_hd(s->bs, bdrv_new());
+ backing = bdrv_new();
+ bdrv_set_backing_hd(s->bs, backing);
+ bdrv_unref(backing);
+
s->bs->backing->bs->drv = &vvfat_write_target;
s->bs->backing->bs->opaque = g_new(void *, 1);
*(void**)s->bs->backing->bs->opaque = s;
diff --git a/include/block/block.h b/include/block/block.h
index 130477c..6dc6766 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -510,6 +510,7 @@ void bdrv_disable_copy_on_read(BlockDriverState *bs);
void bdrv_ref(BlockDriverState *bs);
void bdrv_unref(BlockDriverState *bs);
void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child);
+void bdrv_detach_child(BdrvChild *child);
bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp);
void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason);
--
1.8.3.1
