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qcow2: handle_copied(): Implement non-zero host_offset 

Look only for clusters that start at a given physical offset.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2013-03-26 17:50:08 +01:00 committed by Stefan Hajnoczi
parent c53ede9f6d
commit e62daaf679
1 changed files with 20 additions and 8 deletions
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28
block/qcow2-cluster.c
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@ -830,8 +830,6 @@ static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset,
* the length of the area that can be written to.
*
* -errno: in error cases
*
* TODO Make non-zero host_offset behave like describe above
*/
static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
@ -846,7 +844,6 @@ static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset,
*bytes);
assert(*host_offset == 0);
/*
* Calculate the number of clusters to look for. We stop at L2 table
@ -870,6 +867,16 @@ static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
if (qcow2_get_cluster_type(cluster_offset) == QCOW2_CLUSTER_NORMAL
&& (cluster_offset & QCOW_OFLAG_COPIED))
{
/* If a specific host_offset is required, check it */
bool offset_matches =
(cluster_offset & L2E_OFFSET_MASK) == *host_offset;
if (*host_offset != 0 && !offset_matches) {
*bytes = 0;
ret = 0;
goto out;
}
/* We keep all QCOW_OFLAG_COPIED clusters */
keep_clusters =
count_contiguous_clusters(nb_clusters, s->cluster_size,
@ -883,19 +890,22 @@ static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
ret = 1;
} else {
cluster_offset = 0;
ret = 0;
}
cluster_offset &= L2E_OFFSET_MASK;
*host_offset = cluster_offset;
/* Cleanup */
out:
pret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
if (pret < 0) {
return pret;
}
/* Only return a host offset if we actually made progress. Otherwise we
* would make requirements for handle_alloc() that it can't fulfill */
if (ret) {
*host_offset = cluster_offset & L2E_OFFSET_MASK;
}
return ret;
}
@ -1165,7 +1175,6 @@ again:
/*
* 2. Count contiguous COPIED clusters.
* TODO: Consider cluster_offset if set in step 1c.
*/
uint64_t tmp_bytes = cur_bytes;
ret = handle_copied(bs, offset, &cluster_offset, &tmp_bytes, m);
@ -1179,6 +1188,9 @@ again:
if (!*host_offset) {
*host_offset = cluster_offset;
}
} else if (cur_bytes == 0) {
keep_clusters = 0;
goto done;
} else {
keep_clusters = 0;
}