aboutsummaryrefslogtreecommitdiff
path: root/block.c
diff options
context:
space:
mode:
authorStefan Hajnoczi <stefanha@redhat.com>2017-07-05 13:57:30 +0100
committerMax Reitz <mreitz@redhat.com>2017-07-11 17:45:00 +0200
commit90880ff107ecaada2a06a823dc5fa652f6e37a62 (patch)
treef63e4447193bad024626ead37492cddbd246e2e5 /block.c
parentb43671f80cda8d0f11dcb929ed76fbd680c29cec (diff)
downloadqemu-90880ff107ecaada2a06a823dc5fa652f6e37a62.zip
qemu-90880ff107ecaada2a06a823dc5fa652f6e37a62.tar.gz
qemu-90880ff107ecaada2a06a823dc5fa652f6e37a62.tar.bz2
block: add bdrv_measure() API
bdrv_measure() provides a conservative maximum for the size of a new image. This information is handy if storage needs to be allocated (e.g. a SAN or an LVM volume) ahead of time. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Message-id: 20170705125738.8777-2-stefanha@redhat.com Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r--block.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/block.c b/block.c
index 913bb43..162e9d9 100644
--- a/block.c
+++ b/block.c
@@ -3463,6 +3463,41 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState *bs)
return -ENOTSUP;
}
+/*
+ * bdrv_measure:
+ * @drv: Format driver
+ * @opts: Creation options for new image
+ * @in_bs: Existing image containing data for new image (may be NULL)
+ * @errp: Error object
+ * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo())
+ * or NULL on error
+ *
+ * Calculate file size required to create a new image.
+ *
+ * If @in_bs is given then space for allocated clusters and zero clusters
+ * from that image are included in the calculation. If @opts contains a
+ * backing file that is shared by @in_bs then backing clusters may be omitted
+ * from the calculation.
+ *
+ * If @in_bs is NULL then the calculation includes no allocated clusters
+ * unless a preallocation option is given in @opts.
+ *
+ * Note that @in_bs may use a different BlockDriver from @drv.
+ *
+ * If an error occurs the @errp pointer is set.
+ */
+BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
+ BlockDriverState *in_bs, Error **errp)
+{
+ if (!drv->bdrv_measure) {
+ error_setg(errp, "Block driver '%s' does not support size measurement",
+ drv->format_name);
+ return NULL;
+ }
+
+ return drv->bdrv_measure(opts, in_bs, errp);
+}
+
/**
* Return number of sectors on success, -errno on error.
*/