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[PATCH v8 13/43] block: Use CAFs when working with backing chains
From: |
Max Reitz |
Subject: |
[PATCH v8 13/43] block: Use CAFs when working with backing chains |
Date: |
Tue, 1 Sep 2020 16:33:54 +0200 |
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>
---
block.c | 44 ++++++++++++++++++++++++++++++--------------
1 file changed, 30 insertions(+), 14 deletions(-)
diff --git a/block.c b/block.c
index 887c125400..96bf8672f1 100644
--- a/block.c
+++ b/block.c
@@ -4745,9 +4745,9 @@ int bdrv_change_backing_file(BlockDriverState *bs, const
char *backing_file,
}
/*
- * 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 @@ int bdrv_change_backing_file(BlockDriverState *bs,
const char *backing_file,
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 @@ int bdrv_drop_intermediate(BlockDriverState *top,
BlockDriverState *base,
* 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 @@ BlockDriverState *bdrv_lookup_bs(const char *device,
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 @@ BlockDriverState
*bdrv_find_backing_image(BlockDriverState *bs,
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 @@ BlockDriverState
*bdrv_find_backing_image(BlockDriverState *bs,
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 @@ BlockDriverState
*bdrv_find_backing_image(BlockDriverState *bs,
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 @@ BlockDriverState
*bdrv_find_backing_image(BlockDriverState *bs,
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 @@ BlockDriverState
*bdrv_find_backing_image(BlockDriverState *bs,
g_free(filename_tmp);
if (strcmp(backing_file_full, filename_full) == 0) {
- retval = curr_bs->backing->bs;
+ retval = bs_below;
break;
}
}
--
2.26.2
- [PATCH v8 02/43] block: Add chain helper functions, (continued)
- [PATCH v8 02/43] block: Add chain helper functions, Max Reitz, 2020/09/01
- [PATCH v8 04/43] block: bdrv_set_backing_hd() is about bs->backing, Max Reitz, 2020/09/01
- [PATCH v8 06/43] block: Drop bdrv_is_encrypted(), Max Reitz, 2020/09/01
- [PATCH v8 05/43] block: Include filters when freezing backing chain, Max Reitz, 2020/09/01
- [PATCH v8 07/43] block: Add bdrv_supports_compressed_writes(), Max Reitz, 2020/09/01
- [PATCH v8 08/43] throttle: Support compressed writes, Max Reitz, 2020/09/01
- [PATCH v8 09/43] copy-on-read: Support compressed writes, Max Reitz, 2020/09/01
- [PATCH v8 10/43] block: Use bdrv_filter_(bs|child) where obvious, Max Reitz, 2020/09/01
- [PATCH v8 11/43] block: Use CAFs in block status functions, Max Reitz, 2020/09/01
- [PATCH v8 12/43] stream: Deal with filters, Max Reitz, 2020/09/01
- [PATCH v8 13/43] block: Use CAFs when working with backing chains,
Max Reitz <=
- [PATCH v8 14/43] block: Use bdrv_cow_child() in bdrv_co_truncate(), Max Reitz, 2020/09/01
- [PATCH v8 15/43] block: Re-evaluate backing file handling in reopen, Max Reitz, 2020/09/01
- [PATCH v8 17/43] vmdk: Drop vmdk_co_flush(), Max Reitz, 2020/09/01
- [PATCH v8 16/43] block: Flush all children in generic code, Max Reitz, 2020/09/01
- [PATCH v8 18/43] block: Iterate over children in refresh_limits, Max Reitz, 2020/09/01
- [PATCH v8 19/43] block: Use CAFs in bdrv_refresh_filename(), Max Reitz, 2020/09/01
- [PATCH v8 20/43] block: Use CAF in bdrv_co_rw_vmstate(), Max Reitz, 2020/09/01
- [PATCH v8 21/43] block/snapshot: Fix fallback, Max Reitz, 2020/09/01
- [PATCH v8 24/43] block/null: Implement bdrv_get_allocated_file_size, Max Reitz, 2020/09/01
- [PATCH v8 22/43] block: Use CAFs for debug breakpoints, Max Reitz, 2020/09/01