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qcow2: Prepare handle_alloc/copied() for byte granularity

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This makes handle_alloc() and handle_copied() return byte-granularity
host offsets instead of returning always the cluster start. This is
required so that qcow2_alloc_cluster_offset() can stop aligning
everything to cluster boundaries.

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 17:50:09 +01:00 committed by Stefan Hajnoczi
parent e62daaf679
commit 411d62b04b
1 changed files with 16 additions and 9 deletions
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25
block/qcow2-cluster.c
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@ -817,7 +817,9 @@ static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset,
* *host_offset is not zero, only physically contiguous clusters beginning at
* this host offset are counted.
*
* Note that guest_offset may not be cluster aligned.
* Note that guest_offset may not be cluster aligned. In this case, the
* returned *host_offset points to exact byte referenced by guest_offset and
* therefore isn't cluster aligned as well.
*
* Returns:
* 0: if no allocated clusters are available at the given offset.
@ -845,6 +847,9 @@ 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 || offset_into_cluster(s, guest_offset)
== offset_into_cluster(s, *host_offset));
/*
* Calculate the number of clusters to look for. We stop at L2 table
* boundaries to keep things simple.
@ -903,7 +908,8 @@ out:
/* 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;
*host_offset = (cluster_offset & L2E_OFFSET_MASK)
+ offset_into_cluster(s, guest_offset);
}
return ret;
@ -961,7 +967,9 @@ static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
* copy on write. If *host_offset is non-zero, clusters are only allocated if
* the new allocation can match the specified host offset.
*
* Note that guest_offset may not be cluster aligned.
* Note that guest_offset may not be cluster aligned. In this case, the
* returned *host_offset points to exact byte referenced by guest_offset and
* therefore isn't cluster aligned as well.
*
* Returns:
* 0: if no clusters could be allocated. *bytes is set to 0,
@ -1026,7 +1034,7 @@ static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
}
/* Allocate, if necessary at a given offset in the image file */
alloc_cluster_offset = *host_offset;
alloc_cluster_offset = start_of_cluster(s, *host_offset);
ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset,
&nb_clusters);
if (ret < 0) {
@ -1062,12 +1070,10 @@ static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
>> BDRV_SECTOR_BITS;
int nb_sectors = MIN(requested_sectors, avail_sectors);
*host_offset = alloc_cluster_offset;
*m = g_malloc0(sizeof(**m));
**m = (QCowL2Meta) {
.alloc_offset = *host_offset,
.alloc_offset = alloc_cluster_offset,
.offset = start_of_cluster(s, guest_offset),
.nb_clusters = nb_clusters,
.nb_available = nb_sectors,
@ -1084,6 +1090,7 @@ static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
qemu_co_queue_init(&(*m)->dependent_requests);
QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
*host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
*bytes = MIN(*bytes, (nb_sectors * BDRV_SECTOR_SIZE)
- offset_into_cluster(s, guest_offset));
assert(*bytes != 0);
@ -1186,7 +1193,7 @@ again:
nb_clusters -= keep_clusters;
if (!*host_offset) {
*host_offset = cluster_offset;
*host_offset = start_of_cluster(s, cluster_offset);
}
} else if (cur_bytes == 0) {
keep_clusters = 0;
@ -1228,7 +1235,7 @@ again:
}
if (!*host_offset) {
*host_offset = cluster_offset;
*host_offset = start_of_cluster(s, cluster_offset);
}
nb_clusters = size_to_clusters(s, cur_bytes + offset_into_cluster(s, offset));