bdrv_drop_intermediate used a local list to iterate through backing
chain and delete each BDS. It is simplified while adopting to refcount
mechanism.
Signed-off-by: Fam Zheng <f...@redhat.com>
---
block.c | 71 ++++++++++-------------------------------------------------------
1 file changed, 11 insertions(+), 60 deletions(-)
diff --git a/block.c b/block.c
index 57a3876..499de22 100644
--- a/block.c
+++ b/block.c
@@ -2027,12 +2027,6 @@ BlockDriverState *bdrv_find_overlay(BlockDriverState
*active,
return overlay;
}
-typedef struct BlkIntermediateStates {
- BlockDriverState *bs;
- QSIMPLEQ_ENTRY(BlkIntermediateStates) entry;
-} BlkIntermediateStates;
-
-
/*
* Drops images above 'base' up to and including 'top', and sets the image
* above 'top' to have base as its backing file.
@@ -2062,15 +2056,9 @@ typedef struct BlkIntermediateStates {
int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
BlockDriverState *base)
{
- BlockDriverState *intermediate;
- BlockDriverState *base_bs = NULL;
BlockDriverState *new_top_bs = NULL;
- BlkIntermediateStates *intermediate_state, *next;
int ret = -EIO;
- QSIMPLEQ_HEAD(states_to_delete, BlkIntermediateStates) states_to_delete;
- QSIMPLEQ_INIT(&states_to_delete);
-
if (!top->drv || !base->drv) {
goto exit;
}
@@ -2082,58 +2070,21 @@ int bdrv_drop_intermediate(BlockDriverState *active,
BlockDriverState *top,
goto exit;
}
- /* special case of new_top_bs->backing_hd already pointing to base -
nothing
- * to do, no intermediate images */
- if (new_top_bs->backing_hd == base) {
- ret = 0;
- goto exit;
- }
-
- intermediate = top;
-
- /* now we will go down through the list, and add each BDS we find
- * into our deletion queue, until we hit the 'base'
- */
- while (intermediate) {
- intermediate_state = g_malloc0(sizeof(BlkIntermediateStates));
- intermediate_state->bs = intermediate;
- QSIMPLEQ_INSERT_TAIL(&states_to_delete, intermediate_state, entry);
-
- if (intermediate->backing_hd == base) {
- base_bs = intermediate->backing_hd;
- break;
+ while (new_top_bs->backing_hd && new_top_bs->backing_hd != base) {
+ BlockDriverState *backing = new_top_bs->backing_hd;
+ if (backing == NULL) {
+ goto exit;
}
- intermediate = intermediate->backing_hd;
- }
- if (base_bs == NULL) {
- /* something went wrong, we did not end at the base. safely
- * unravel everything, and exit with error */
- goto exit;
+ new_top_bs->backing_hd = backing->backing_hd;
+ /* break backing_hd chain before releasing bs, so we don't free all the
+ * way up the backing chain */
+ backing->backing_hd = NULL;
+ bdrv_unref(backing, false);
}
- /* success - we can delete the intermediate states, and link top->base */
- ret = bdrv_change_backing_file(new_top_bs, base_bs->filename,
- base_bs->drv ? base_bs->drv->format_name :
"");
- if (ret) {
- goto exit;
- }
- if (new_top_bs->backing_hd) {
- bdrv_unref(new_top_bs->backing_hd, false);
- }
- new_top_bs->backing_hd = base_bs;
- bdrv_ref(base_bs, false);
-
- QSIMPLEQ_FOREACH_SAFE(intermediate_state, &states_to_delete, entry, next) {
- /* so that bdrv_close() does not recursively close the chain */
- intermediate_state->bs->backing_hd = NULL;
- bdrv_delete(intermediate_state->bs);
- }
- ret = 0;
-
+ ret = bdrv_change_backing_file(new_top_bs, base->filename,
+ base->drv ? base->drv->format_name : "");
exit:
- QSIMPLEQ_FOREACH_SAFE(intermediate_state, &states_to_delete, entry, next) {
- g_free(intermediate_state);
- }
return ret;
}
--
1.8.3.2
