Hi Kevin,
> A correct reopen implementation must consider all options and flags that
> .bdrv_open() looked at.
>
> The options are okay, as both "filename" and "password-secret" aren't
> things that we want to allow a reopen to change. However, in the flags
> BDRV_O_NOCACHE makes a difference:
>
> if (flags & BDRV_O_NOCACHE) {
> rados_conf_set(s->cluster, "rbd_cache", "false");
> } else {
> rados_conf_set(s->cluster, "rbd_cache", "true");
> }
>
> A reopen must either update the setting, or if it can't (e.g. because
> librbd doesn't support it) any attempt to change the flag must fail.
Thanks for the feedback.
As far as i can tell it's not possible to update the cache settings
without reconnecting. I've added a check in the following patch.
Would be great if someone who knows the internals of ceph/rbd could
have a look as well.
Sebastian
-- >8 --
Subject: [PATCH] block/rbd: add .bdrv_reopen_prepare() stub
Add support for reopen() by adding the .bdrv_reopen_prepare() stub
Signed-off-by: Sebastian Färber <sfaerbe...@gmail.com>
---
block/rbd.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/block/rbd.c b/block/rbd.c
index 5bc5b32..8ecf096 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -577,6 +577,19 @@ failed_opts:
return r;
}
+/* Note that this will not re-establish a connection with the Ceph cluster
+ - it is effectively a NOP. */
+static int qemu_rbd_reopen_prepare(BDRVReopenState *state,
+ BlockReopenQueue *queue, Error **errp)
+{
+ if (state->flags & BDRV_O_NOCACHE &&
+ ((state->bs->open_flags & BDRV_O_NOCACHE) == 0)) {
+ error_setg(errp, "Cannot turn off rbd_cache during reopen");
+ return -EINVAL;
+ }
+ return 0;
+}
+
static void qemu_rbd_close(BlockDriverState *bs)
{
BDRVRBDState *s = bs->opaque;
@@ -976,6 +989,7 @@ static BlockDriver bdrv_rbd = {
.instance_size = sizeof(BDRVRBDState),
.bdrv_needs_filename = true,
.bdrv_file_open = qemu_rbd_open,
+ .bdrv_reopen_prepare = qemu_rbd_reopen_prepare,
.bdrv_close = qemu_rbd_close,
.bdrv_create = qemu_rbd_create,
.bdrv_has_zero_init = bdrv_has_zero_init_1,
--
1.8.3.1
