It looks like this has hit a 30 day expiration without any reviews or
being merged; do we still want this? If so, can you please resend?
On 5/10/19 11:33 AM, Stefano Garzarella wrote:
> This patch allows 'qemu-img info' to show the 'disk size' for
> the RBD images that have the fast-diff feature enabled.
>
> If this feature is enabled, we use the rbd_diff_iterate2() API
> to calculate the allocated size for the image.
>
> Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
> ---
> v2:
> - calculate the actual usage only if the fast-diff feature is
> enabled [Jason]
> ---
> block/rbd.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 54 insertions(+)
>
> diff --git a/block/rbd.c b/block/rbd.c
> index 0c549c9935..f1bc76ab80 100644
> --- a/block/rbd.c
> +++ b/block/rbd.c
> @@ -1046,6 +1046,59 @@ static int64_t qemu_rbd_getlength(BlockDriverState *bs)
> return info.size;
> }
>
> +static int rbd_allocated_size_cb(uint64_t offset, size_t len, int exists,
> + void *arg)
> +{
> + int64_t *alloc_size = (int64_t *) arg;
> +
> + if (exists) {
> + (*alloc_size) += len;
> + }
> +
> + return 0;
> +}
> +
> +static int64_t qemu_rbd_get_allocated_file_size(BlockDriverState *bs)
> +{
> + BDRVRBDState *s = bs->opaque;
> + uint64_t flags, features;
> + int64_t alloc_size = 0;
> + int r;
> +
> + r = rbd_get_flags(s->image, &flags);
> + if (r < 0) {
> + return r;
> + }
> +
Do you know where rbd_get_flags is documented? I can't seem to quickly
find a reference that tells me what to expect from calling it. It
returns an int, I guess an error code, but how can I confirm this?
*clones the ceph repository*
src/librbd/internal.cc get_flags convinces me it probably works like I
think, but is there not a reference here?
> + r = rbd_get_features(s->image, &features);
> + if (r < 0) {
> + return r;
> + }
> +
> + /*
> + * We use rbd_diff_iterate2() only if the RBD image have fast-diff
> + * feature enabled. If it is disabled, rbd_diff_iterate2() could be
> + * very slow on a big image.
> + */
> + if (!(features & RBD_FEATURE_FAST_DIFF) ||
> + (flags & RBD_FLAG_FAST_DIFF_INVALID)) {
> + return -1;
> + }
> +
(Is there a reference for the list of flags to make sure there aren't
other cases we might want to skip this?)
It looks reasonable at a glance, but maybe let's return -ENOTSUP instead
of -1, based on the idea that bdrv_get_allocated_file_size returns
-ENOMEDIUM in a prominent error case -- let's match that error convention.
(Well, I wonder what the librbd calls are returning and if THOSE mean
anything.)
> + /*
> + * rbd_diff_iterate2(), if the source snapshot name is NULL, invokes
> + * the callback on all allocated regions of the image.
> + */
> + r = rbd_diff_iterate2(s->image, NULL, 0,
> + bs->total_sectors * BDRV_SECTOR_SIZE, 0, 1,
> + &rbd_allocated_size_cb, &alloc_size);
> + if (r < 0) {
> + return r;
> + }
> +
I guess I'll take your word for it. ¯\_(ツ)_/¯
> + return alloc_size;
> +}
> +
> static int coroutine_fn qemu_rbd_co_truncate(BlockDriverState *bs,
> int64_t offset,
> PreallocMode prealloc,
> @@ -1254,6 +1307,7 @@ static BlockDriver bdrv_rbd = {
> .bdrv_get_info = qemu_rbd_getinfo,
> .create_opts = &qemu_rbd_create_opts,
> .bdrv_getlength = qemu_rbd_getlength,
> + .bdrv_get_allocated_file_size = qemu_rbd_get_allocated_file_size,
> .bdrv_co_truncate = qemu_rbd_co_truncate,
> .protocol_name = "rbd",
>
>
