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Tue, 25 Aug 2020 08:33:48 +0000 (UTC) Received: from localhost (ovpn-113-72.ams2.redhat.com [10.36.113.72]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 08D9B5D9CA; Tue, 25 Aug 2020 08:33:47 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PULL 15/34] qcow2: Add qcow2_get_subcluster_range_type() Date: Tue, 25 Aug 2020 10:32:52 +0200 Message-Id: <20200825083311.1098442-16-mreitz@redhat.com> In-Reply-To: <20200825083311.1098442-1-mreitz@redhat.com> References: <20200825083311.1098442-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/25 02:03:58 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.956, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Peter Maydell , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Alberto Garcia There are situations in which we want to know how many contiguous subclusters of the same type there are in a given cluster. This can be done by simply iterating over the subclusters and repeatedly calling qcow2_get_subcluster_type() for each one of them. However once we determined the type of a subcluster we can check the rest efficiently by counting the number of adjacent ones (or zeroes) in the bitmap. This is what this function does. Signed-off-by: Alberto Garcia Reviewed-by: Eric Blake Reviewed-by: Max Reitz Message-Id: Signed-off-by: Max Reitz --- block/qcow2-cluster.c | 51 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 0b762502f6..2fe7a0f79c 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -375,6 +375,57 @@ fail: return ret; } +/* + * For a given L2 entry, count the number of contiguous subclusters of + * the same type starting from @sc_from. Compressed clusters are + * treated as if they were divided into subclusters of size + * s->subcluster_size. + * + * Return the number of contiguous subclusters and set @type to the + * subcluster type. + * + * If the L2 entry is invalid return -errno and set @type to + * QCOW2_SUBCLUSTER_INVALID. + */ +G_GNUC_UNUSED +static int qcow2_get_subcluster_range_type(BlockDriverState *bs, + uint64_t l2_entry, + uint64_t l2_bitmap, + unsigned sc_from, + QCow2SubclusterType *type) +{ + BDRVQcow2State *s = bs->opaque; + uint32_t val; + + *type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_from); + + if (*type == QCOW2_SUBCLUSTER_INVALID) { + return -EINVAL; + } else if (!has_subclusters(s) || *type == QCOW2_SUBCLUSTER_COMPRESSED) { + return s->subclusters_per_cluster - sc_from; + } + + switch (*type) { + case QCOW2_SUBCLUSTER_NORMAL: + val = l2_bitmap | QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from); + return cto32(val) - sc_from; + + case QCOW2_SUBCLUSTER_ZERO_PLAIN: + case QCOW2_SUBCLUSTER_ZERO_ALLOC: + val = (l2_bitmap | QCOW_OFLAG_SUB_ZERO_RANGE(0, sc_from)) >> 32; + return cto32(val) - sc_from; + + case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: + case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: + val = ((l2_bitmap >> 32) | l2_bitmap) + & ~QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from); + return ctz32(val) - sc_from; + + default: + g_assert_not_reached(); + } +} + /* * Checks how many clusters in a given L2 slice are contiguous in the image * file. As soon as one of the flags in the bitmask stop_flags changes compared