On 23.10.2020 17:45, Vladimir Sementsov-Ogievskiy wrote:
22.10.2020 21:13, Andrey Shinkevich wrote:
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);
QERR_BASE_NOT_FOUND is unrelated here. Also, I see a comment in qerror.h
that such macros should not be used in new code. And don't forget to
drop qerror.h include line.
I have been surprized because I don't have it in my branch and instead I do:
error_setg(errp, "Bottom node '%s' not found", bottom_node);
+ qdict_del(options, "bottom");
this may be moved above "bottom_bs = ..", to not call it after "if" in
separate.
Please, see the "Re: [PATCH v11 04/13] copy-on-read: pass overlay base
node name to COR driver".
+ 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
