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block/copy-before-write: bdrv_cbw_append(): replace child at last

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Refactor the function to replace child at last. Thus we don't need to
revert it and code is simplified.

block-copy state initialization being done before replacing the child
doesn't need any drained section.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-14-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2021-08-24 11:38:35 +03:00 committed by Hanna Reitz
parent 3c1e63277e
commit 7ddbce2dec
1 changed files with 11 additions and 22 deletions
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31
block/copy-before-write.c
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@ -172,7 +172,6 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
int ret;
BDRVCopyBeforeWriteState *state;
BlockDriverState *top;
bool appended = false;
assert(source->total_sectors == target->total_sectors);
@ -196,8 +195,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
BDRV_CHILD_DATA, errp);
if (!state->target) {
error_prepend(errp, "Cannot attach target child: ");
bdrv_unref(top);
return NULL;
goto fail;
}
bdrv_ref(source);
@ -206,18 +204,8 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
errp);
if (!top->file) {
error_prepend(errp, "Cannot attach file child: ");
bdrv_unref(top);
return NULL;
}
bdrv_drained_begin(source);
ret = bdrv_replace_node(source, top, errp);
if (ret < 0) {
error_prepend(errp, "Cannot append copy-before-write filter: ");
goto fail;
}
appended = true;
state->bcs = block_copy_state_new(top->file, state->target, false, compress,
errp);
@ -225,21 +213,22 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
error_prepend(errp, "Cannot create block-copy-state: ");
goto fail;
}
*bcs = state->bcs;
bdrv_drained_begin(source);
ret = bdrv_replace_node(source, top, errp);
bdrv_drained_end(source);
if (ret < 0) {
error_prepend(errp, "Cannot append copy-before-write filter: ");
goto fail;
}
*bcs = state->bcs;
return top;
fail:
if (appended) {
bdrv_cbw_drop(top);
} else {
block_copy_state_free(state->bcs);
bdrv_unref(top);
}
bdrv_drained_end(source);
return NULL;
}