We are going to use the COR-filter for a block-stream job. To limit COR operations by the base node in the backing chain during stream job, pass the bottom node name, that is the first non-filter overlay of the base, to the copy-on-read driver as the base node itself may change due to possible concurrent jobs. The rest of the functionality will be implemented in the patch that follows.
Signed-off-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com> --- block/copy-on-read.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/block/copy-on-read.c b/block/copy-on-read.c index 618c4c4..3d8e4db 100644 --- a/block/copy-on-read.c +++ b/block/copy-on-read.c @@ -24,18 +24,24 @@ #include "block/block_int.h" #include "qemu/module.h" #include "qapi/error.h" +#include "qapi/qmp/qerror.h" +#include "qapi/qmp/qdict.h" #include "block/copy-on-read.h" typedef struct BDRVStateCOR { bool active; + BlockDriverState *bottom_bs; } BDRVStateCOR; static int cor_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { + BlockDriverState *bottom_bs = NULL; BDRVStateCOR *state = bs->opaque; + /* Find a bottom node name, if any */ + const char *bottom_node = qdict_get_try_str(options, "bottom"); bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds, BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, @@ -51,7 +57,17 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags, ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) & bs->file->bs->supported_zero_flags); + if (bottom_node) { + bottom_bs = bdrv_lookup_bs(NULL, bottom_node, errp); + if (!bottom_bs) { + error_setg(errp, QERR_BASE_NOT_FOUND, bottom_node); + qdict_del(options, "bottom"); + return -EINVAL; + } + qdict_del(options, "bottom"); + } state->active = true; + state->bottom_bs = bottom_bs; /* * We don't need to call bdrv_child_refresh_perms() now as the permissions -- 1.8.3.1