13.06.2019 1:09, Max Reitz wrote: > Use child access functions when iterating through backing chains so > filters do not break the chain. > > Signed-off-by: Max Reitz <mre...@redhat.com> > --- > block.c | 40 ++++++++++++++++++++++++++++------------ > 1 file changed, 28 insertions(+), 12 deletions(-) > > diff --git a/block.c b/block.c > index 11f37983d9..505b3e9a01 100644 > --- a/block.c > +++ b/block.c > @@ -4261,7 +4261,8 @@ int bdrv_change_backing_file(BlockDriverState *bs, > } > > /* > - * Finds the image layer in the chain that has 'bs' as its backing file. > + * Finds the image layer in the chain that has 'bs' (or a filter on > + * top of it) as its backing file. > * > * active is the current topmost image. > * > @@ -4273,11 +4274,18 @@ int bdrv_change_backing_file(BlockDriverState *bs, > BlockDriverState *bdrv_find_overlay(BlockDriverState *active, > BlockDriverState *bs) > { > - while (active && bs != backing_bs(active)) { > - active = backing_bs(active); > + bs = bdrv_skip_rw_filters(bs); > + active = bdrv_skip_rw_filters(active); > + > + while (active) { > + BlockDriverState *next = bdrv_backing_chain_next(active); > + if (bs == next) { > + return active; > + } > + active = next; > } > > - return active; > + return NULL; > }
Semantics changed for this function. It is used in two places 1. from bdrv_find_base wtih @bs=NULL, it should be unchanged, as I hope we will never have filter node as a bottom of some valid chain 2. from qmp_block_commit, only to check op-blocker... hmmm. I really don't understand, why do we check BLOCK_OP_TYPE_COMMIT_TARGET on top_bs overlay.. top_bs overlay is out of the job, what is this check for? > > /* Given a BDS, searches for the base layer. */ > @@ -4421,9 +4429,7 @@ 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 > */ > @@ -4902,7 +4908,7 @@ 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_filtered_bs(top); > } > > return top != NULL; > @@ -5141,7 +5147,17 @@ 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_rw_filters(bs); > + bdrv_filtered_cow_child(curr_bs) != NULL; > + curr_bs = bdrv_backing_chain_next(curr_bs)) > + { > + BlockDriverState *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 */ > @@ -5149,7 +5165,7 @@ BlockDriverState > *bdrv_find_backing_image(BlockDriverState *bs, > char *backing_file_full_ret; > > if (strcmp(backing_file, curr_bs->backing_file) == 0) { hmm, interesting, what bs->backing_file now means? It's strange enough to store such field on bds, when we have backing link anyway.. > - retval = curr_bs->backing->bs; > + retval = bs_below; > break; > } > /* Also check against the full backing filename for the image */ > @@ -5159,7 +5175,7 @@ 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; > } > } > @@ -5185,7 +5201,7 @@ 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; > } > } > -- Best regards, Vladimir