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[Qemu-devel] [PATCH 04/19] qcow2: Ignore reserved bits in count_contiguo
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 04/19] qcow2: Ignore reserved bits in count_contiguous_clusters() |
Date: |
Thu, 12 Apr 2012 17:01:05 +0200 |
Until now, count_contiguous_clusters() has an argument that allowed to
specify flags that should be ignored in the comparison, i.e. that are
allowed to change between contiguous clusters.
This patch changes the function so that it ignores all flags by default
now and you need to pass the flags on which it should stop.
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow2-cluster.c | 38 ++++++++++++++++++++++++++++----------
1 files changed, 28 insertions(+), 10 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 44d13de..9547fa9 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -246,28 +246,44 @@ fail:
return ret;
}
+/*
+ * Checks how many clusters in a given L2 table are contiguous in the image
+ * file. As soon as one of the flags in the bitmask stop_flags changes compared
+ * to the first cluster, the search is stopped and the cluster is not counted
+ * as contiguous. (This allows it, for example, to stop at the first compressed
+ * cluster which may require a different handling)
+ */
static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size,
- uint64_t *l2_table, uint64_t start, uint64_t mask)
+ uint64_t *l2_table, uint64_t start, uint64_t stop_flags)
{
int i;
- uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask;
+ uint64_t mask = stop_flags | L2E_OFFSET_MASK;
+ uint64_t offset = be64_to_cpu(l2_table[0]) & mask;
if (!offset)
return 0;
- for (i = start; i < start + nb_clusters; i++)
- if (offset + (uint64_t) i * cluster_size != (be64_to_cpu(l2_table[i])
& ~mask))
+ for (i = start; i < start + nb_clusters; i++) {
+ uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask;
+ if (offset + (uint64_t) i * cluster_size != l2_entry) {
break;
+ }
+ }
return (i - start);
}
static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t
*l2_table)
{
- int i = 0;
+ int i;
- while(nb_clusters-- && l2_table[i] == 0)
- i++;
+ for (i = 0; i < nb_clusters; i++) {
+ int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i]));
+
+ if (type != QCOW2_CLUSTER_UNALLOCATED) {
+ break;
+ }
+ }
return i;
}
@@ -444,7 +460,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t
offset,
case QCOW2_CLUSTER_NORMAL:
/* how many allocated clusters ? */
c = count_contiguous_clusters(nb_clusters, s->cluster_size,
- &l2_table[l2_index], 0, QCOW_OFLAG_COPIED);
+ &l2_table[l2_index], 0, QCOW_OFLAG_COMPRESSED);
*cluster_offset &= L2E_OFFSET_MASK;
break;
}
@@ -696,7 +712,8 @@ static int count_cow_clusters(BDRVQcowState *s, int
nb_clusters,
while (i < nb_clusters) {
i += count_contiguous_clusters(nb_clusters - i, s->cluster_size,
- &l2_table[l2_index], i, 0);
+ &l2_table[l2_index], i,
+ QCOW_OFLAG_COPIED | QCOW_OFLAG_COMPRESSED);
if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) {
break;
}
@@ -854,7 +871,8 @@ again:
if (cluster_offset & QCOW_OFLAG_COPIED) {
/* We keep all QCOW_OFLAG_COPIED clusters */
keep_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size,
- &l2_table[l2_index], 0, 0);
+ &l2_table[l2_index], 0,
+ QCOW_OFLAG_COPIED);
assert(keep_clusters <= nb_clusters);
nb_clusters -= keep_clusters;
} else {
--
1.7.6.5
- [Qemu-devel] [PATCH 00/19] qcow2: Add basic version 3 support, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 01/19] Specification for qcow2 version 3, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 05/19] qcow2: Fail write_compressed when overwriting data, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 04/19] qcow2: Ignore reserved bits in count_contiguous_clusters(),
Kevin Wolf <=
- [Qemu-devel] [PATCH 03/19] qcow2: Ignore reserved bits in get_cluster_offset, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 02/19] qcow2: Save disk size in snapshot header, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 09/19] qcow2: Ignore reserved bits in refcount table entries, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 07/19] qcow2: Refactor qcow2_free_any_clusters, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 10/19] qcow2: Ignore reserved bits in check_refcounts, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 18/19] [RFC] Possible qcow2 specification extensions, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 06/19] qcow2: Ignore reserved bits in L1/L2 entries, Kevin Wolf, 2012/04/12
- [Qemu-devel] [PATCH 11/19] qcow2: Version 3 images, Kevin Wolf, 2012/04/12