aboutsummaryrefslogtreecommitdiff
path: root/block/qcow2-refcount.c
diff options
context:
space:
mode:
authorPavel Butsykin <pbutsykin@virtuozzo.com>2017-09-29 15:16:13 +0300
committerMax Reitz <mreitz@redhat.com>2017-10-06 16:30:48 +0200
commit163bc39d2c2921430e5c23f4d0a0966d62f67a02 (patch)
treed0303bc2a7e3d2d346d8c1d7d361f5a453c8aed4 /block/qcow2-refcount.c
parent76a2a30a99c670e9ec1b4a5d976868059c6bc258 (diff)
downloadqemu-163bc39d2c2921430e5c23f4d0a0966d62f67a02.zip
qemu-163bc39d2c2921430e5c23f4d0a0966d62f67a02.tar.gz
qemu-163bc39d2c2921430e5c23f4d0a0966d62f67a02.tar.bz2
qcow2: truncate the tail of the image file after shrinking the image
Now after shrinking the image, at the end of the image file, there might be a tail that probably will never be used. So we can find the last used cluster and cut the tail. Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 20170929121613.25997-3-pbutsykin@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block/qcow2-refcount.c')
-rw-r--r--block/qcow2-refcount.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 88d5a3f..aa3fd6c 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -3181,3 +3181,25 @@ out:
g_free(reftable_tmp);
return ret;
}
+
+int64_t qcow2_get_last_cluster(BlockDriverState *bs, int64_t size)
+{
+ BDRVQcow2State *s = bs->opaque;
+ int64_t i;
+
+ for (i = size_to_clusters(s, size) - 1; i >= 0; i--) {
+ uint64_t refcount;
+ int ret = qcow2_get_refcount(bs, i, &refcount);
+ if (ret < 0) {
+ fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n",
+ i, strerror(-ret));
+ return ret;
+ }
+ if (refcount > 0) {
+ return i;
+ }
+ }
+ qcow2_signal_corruption(bs, true, -1, -1,
+ "There are no references in the refcount table.");
+ return -EIO;
+}