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qcow2: Convert qcow2_alloc_cluster_offset() into qcow2_alloc_host_offset()

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qcow2_alloc_cluster_offset() takes an (unaligned) guest offset and
returns the (aligned) offset of the corresponding cluster in the qcow2
image.

In practice none of the callers need to know where the cluster starts
so this patch makes the function calculate and return the final host
offset directly. The function is also renamed accordingly.

See 388e581615 for a similar change to qcow2_get_cluster_offset().

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-Id: <9bfef50ec9200d752413be4fc2aeb22a28378817.1599833007.git.berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Alberto Garcia 2020-09-11 16:09:42 +02:00 • committed by Max Reitz
parent 8e958260c5
commit bfd0989acf
3 changed files with 26 additions and 30 deletions
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14
block/qcow2-cluster.c
View file

@ -1719,6 +1719,10 @@ out:
* clusters (or subclusters) if necessary. The result can span a
* combination of allocated and previously unallocated clusters.
*
* Note that offset may not be cluster aligned. In this case, the returned
* *host_offset points to exact byte referenced by offset and therefore
* isn't cluster aligned as well.
*
* On return, @host_offset is set to the beginning of the requested
* area. This area is guaranteed to be contiguous on the qcow2 file
* but it can be smaller than initially requested. In this case @bytes
@ -1736,9 +1740,9 @@ out:
*
* Return 0 on success and -errno in error cases
*/
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
unsigned int *bytes, uint64_t *host_offset,
QCowL2Meta **m)
int qcow2_alloc_host_offset(BlockDriverState *bs, uint64_t offset,
unsigned int *bytes, uint64_t *host_offset,
QCowL2Meta **m)
{
BDRVQcow2State *s = bs->opaque;
uint64_t start, remaining;
@ -1759,7 +1763,7 @@ again:
while (true) {
if (*host_offset == INV_OFFSET && cluster_offset != INV_OFFSET) {
*host_offset = start_of_cluster(s, cluster_offset);
*host_offset = cluster_offset;
}
assert(remaining >= cur_bytes);
@ -1842,6 +1846,8 @@ again:
*bytes -= remaining;
assert(*bytes > 0);
assert(*host_offset != INV_OFFSET);
assert(offset_into_cluster(s, *host_offset) ==
offset_into_cluster(s, offset));
return 0;
}