From: Max Reitz <mreitz@redhat.com>
To: qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
Peter Maydell <peter.maydell@linaro.org>,
qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>
Subject: [PULL 15/34] qcow2: Add qcow2_get_subcluster_range_type()
Date: Tue, 25 Aug 2020 10:32:52 +0200 [thread overview]
Message-ID: <20200825083311.1098442-16-mreitz@redhat.com> (raw)
In-Reply-To: <20200825083311.1098442-1-mreitz@redhat.com>
From: Alberto Garcia <berto@igalia.com>
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 <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <db917263d568ec6ffb4a41cac3c9100f96bf6c18.1594396418.git.berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
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
--
2.26.2
next prev parent reply other threads:[~2020-08-25 8:38 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 8:32 [PULL 00/34] Block patches Max Reitz
2020-08-25 8:32 ` [PULL 01/34] qcow2: Make Qcow2AioTask store the full host offset Max Reitz
2020-08-25 8:32 ` [PULL 02/34] qcow2: Convert qcow2_get_cluster_offset() into qcow2_get_host_offset() Max Reitz
2020-08-25 8:32 ` [PULL 03/34] qcow2: Add calculate_l2_meta() Max Reitz
2020-08-25 8:32 ` [PULL 04/34] qcow2: Split cluster_needs_cow() out of count_cow_clusters() Max Reitz
2020-08-25 8:32 ` [PULL 05/34] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied() Max Reitz
2020-08-25 8:32 ` [PULL 06/34] qcow2: Add get_l2_entry() and set_l2_entry() Max Reitz
2020-08-25 8:32 ` [PULL 07/34] qcow2: Document the Extended L2 Entries feature Max Reitz
2020-08-25 8:32 ` [PULL 08/34] qcow2: Add dummy has_subclusters() function Max Reitz
2020-08-25 8:32 ` [PULL 09/34] qcow2: Add subcluster-related fields to BDRVQcow2State Max Reitz
2020-08-25 8:32 ` [PULL 10/34] qcow2: Add offset_to_sc_index() Max Reitz
2020-08-25 8:32 ` [PULL 11/34] qcow2: Add offset_into_subcluster() and size_to_subclusters() Max Reitz
2020-08-25 8:32 ` [PULL 12/34] qcow2: Add l2_entry_size() Max Reitz
2020-08-25 8:32 ` [PULL 13/34] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap() Max Reitz
2020-08-25 8:32 ` [PULL 14/34] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type() Max Reitz
2020-08-25 8:32 ` Max Reitz [this message]
2020-08-25 8:32 ` [PULL 16/34] qcow2: Add qcow2_cluster_is_allocated() Max Reitz
2020-08-25 8:32 ` [PULL 17/34] qcow2: Add cluster type parameter to qcow2_get_host_offset() Max Reitz
2020-08-25 8:32 ` [PULL 18/34] qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_* Max Reitz
2020-08-25 8:32 ` [PULL 19/34] qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC Max Reitz
2020-08-25 8:32 ` [PULL 20/34] qcow2: Add subcluster support to calculate_l2_meta() Max Reitz
2020-08-25 8:32 ` [PULL 21/34] qcow2: Add subcluster support to qcow2_get_host_offset() Max Reitz
2020-08-25 8:32 ` [PULL 22/34] qcow2: Add subcluster support to zero_in_l2_slice() Max Reitz
2020-08-25 8:33 ` [PULL 23/34] qcow2: Add subcluster support to discard_in_l2_slice() Max Reitz
2020-08-25 8:33 ` [PULL 24/34] qcow2: Add subcluster support to check_refcounts_l2() Max Reitz
2020-08-25 8:33 ` [PULL 25/34] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2() Max Reitz
2020-08-25 8:33 ` [PULL 26/34] qcow2: Clear the L2 bitmap when allocating a compressed cluster Max Reitz
2020-08-25 8:33 ` [PULL 27/34] qcow2: Add subcluster support to handle_alloc_space() Max Reitz
2020-08-25 8:33 ` [PULL 28/34] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes() Max Reitz
2020-08-25 8:33 ` [PULL 29/34] qcow2: Add subcluster support to qcow2_measure() Max Reitz
2020-08-25 8:33 ` [PULL 30/34] qcow2: Add prealloc field to QCowL2Meta Max Reitz
2020-08-25 8:33 ` [PULL 31/34] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit Max Reitz
2020-08-25 8:33 ` [PULL 32/34] qcow2: Allow preallocation and backing files if extended_l2 is set Max Reitz
2020-08-25 8:33 ` [PULL 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters Max Reitz
2020-08-25 8:33 ` [PULL 34/34] iotests: Add tests for qcow2 images with extended L2 entries Max Reitz
2020-08-25 14:01 ` [PULL 00/34] Block patches Peter Maydell
2020-08-25 14:22 ` Alberto Garcia
2020-08-25 15:13 ` Max Reitz
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