block: Use CAFs when working with backing chains
Use child access functions when iterating through backing chains so
filters do not break the chain.
In addition, bdrv_find_overlay() will now always return the actual
overlay; that is, it will never return a filter node but only one with a
COW backing file (there may be filter nodes between that node and @bs).
Signed-off-by: Max Reitz <mreitz@redhat.com>
diff --git a/block.c b/block.c
index 887c125..96bf867 100644
--- a/block.c
+++ b/block.c
@@ -4745,9 +4745,9 @@
}
/*
- * Finds the image layer in the chain that has 'bs' as its backing file.
- *
- * active is the current topmost image.
+ * Finds the first non-filter node above bs in the chain between
+ * active and bs. The returned node is either an immediate parent of
+ * bs, or there are only filter nodes between the two.
*
* Returns NULL if bs is not found in active's image chain,
* or if active == bs.
@@ -4757,11 +4757,18 @@
BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
BlockDriverState *bs)
{
- while (active && bs != backing_bs(active)) {
- active = backing_bs(active);
+ bs = bdrv_skip_filters(bs);
+ active = bdrv_skip_filters(active);
+
+ while (active) {
+ BlockDriverState *next = bdrv_backing_chain_next(active);
+ if (bs == next) {
+ return active;
+ }
+ active = next;
}
- return active;
+ return NULL;
}
/* Given a BDS, searches for the base layer. */
@@ -4913,9 +4920,7 @@
* other intermediate nodes have been dropped.
* If 'top' is an implicit node (e.g. "commit_top") we should skip
* it because no one inherits from it. We use explicit_top for that. */
- while (explicit_top && explicit_top->implicit) {
- explicit_top = backing_bs(explicit_top);
- }
+ explicit_top = bdrv_skip_implicit_filters(explicit_top);
update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
/* success - we can delete the intermediate states, and link top->base */
@@ -5372,7 +5377,7 @@
bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
{
while (top && top != base) {
- top = backing_bs(top);
+ top = bdrv_filter_or_cow_bs(top);
}
return top != NULL;
@@ -5613,6 +5618,7 @@
int is_protocol = 0;
BlockDriverState *curr_bs = NULL;
BlockDriverState *retval = NULL;
+ BlockDriverState *bs_below;
if (!bs || !bs->drv || !backing_file) {
return NULL;
@@ -5623,7 +5629,17 @@
is_protocol = path_has_protocol(backing_file);
- for (curr_bs = bs; curr_bs->backing; curr_bs = curr_bs->backing->bs) {
+ /*
+ * Being largely a legacy function, skip any filters here
+ * (because filters do not have normal filenames, so they cannot
+ * match anyway; and allowing json:{} filenames is a bit out of
+ * scope).
+ */
+ for (curr_bs = bdrv_skip_filters(bs);
+ bdrv_cow_child(curr_bs) != NULL;
+ curr_bs = bs_below)
+ {
+ bs_below = bdrv_backing_chain_next(curr_bs);
/* If either of the filename paths is actually a protocol, then
* compare unmodified paths; otherwise make paths relative */
@@ -5631,7 +5647,7 @@
char *backing_file_full_ret;
if (strcmp(backing_file, curr_bs->backing_file) == 0) {
- retval = curr_bs->backing->bs;
+ retval = bs_below;
break;
}
/* Also check against the full backing filename for the image */
@@ -5641,7 +5657,7 @@
bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
g_free(backing_file_full_ret);
if (equal) {
- retval = curr_bs->backing->bs;
+ retval = bs_below;
break;
}
}
@@ -5667,7 +5683,7 @@
g_free(filename_tmp);
if (strcmp(backing_file_full, filename_full) == 0) {
- retval = curr_bs->backing->bs;
+ retval = bs_below;
break;
}
}
