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[Qemu-devel] [PATCH 4/7] block: simplify bdrv_drop_intermediate
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PATCH 4/7] block: simplify bdrv_drop_intermediate |
Date: |
Tue, 2 Jul 2013 13:59:46 +0800 |
Signed-off-by: Fam Zheng <address@hidden>
---
block.c | 71 ++++++++++-------------------------------------------------------
1 file changed, 11 insertions(+), 60 deletions(-)
diff --git a/block.c b/block.c
index d1ce570..ae5de17 100644
--- a/block.c
+++ b/block.c
@@ -2015,12 +2015,6 @@ 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.
@@ -2050,15 +2044,9 @@ 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;
}
@@ -2070,58 +2058,21 @@ 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_put_ref(backing);
}
- /* 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_put_ref(new_top_bs->backing_hd);
- }
- new_top_bs->backing_hd = base_bs;
- bdrv_get_ref(base_bs);
-
- 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_put_ref(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;
}
--
1.8.3.1
- Re: [Qemu-devel] [PATCH 1/7] block: Convert BlockDriverState.in_use to refcount, (continued)
[Qemu-devel] [PATCH 4/7] block: simplify bdrv_drop_intermediate,
Fam Zheng <=
[Qemu-devel] [PATCH 5/7] block: rename bdrv_in_use to bdrv_is_shared, Fam Zheng, 2013/07/02
[Qemu-devel] [PATCH 6/7] block: add target-id option to drive-backup QMP command, Fam Zheng, 2013/07/02
[Qemu-devel] [PATCH 7/7] block: assign backing relationship in drive-backup, Fam Zheng, 2013/07/02