From bfd0989acffe0b348a4be5155a4688d92c34b1ef Mon Sep 17 00:00:00 2001 From: Alberto Garcia Date: Fri, 11 Sep 2020 16:09:42 +0200 Subject: qcow2: Convert qcow2_alloc_cluster_offset() into qcow2_alloc_host_offset() 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 Message-Id: <9bfef50ec9200d752413be4fc2aeb22a28378817.1599833007.git.berto@igalia.com> Reviewed-by: Max Reitz Signed-off-by: Max Reitz --- block/qcow2-cluster.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'block/qcow2-cluster.c') diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 1a67b2d928..9acc6ce4ae 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -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; } -- cgit v1.2.3