qcow2: Update qcow2_get_cluster_offset() to support L2 slices
qcow2_get_cluster_offset() checks how many contiguous bytes are available at a given offset. The returned number of bytes is limited by the amount that can be addressed without having to load more than one L2 table. Since we'll be loading L2 slices instead of full tables this patch changes the limit accordingly using the size of the L2 slice for the calculations instead of the full table size. One consequence of this is that with small L2 slices operations such as 'qemu-img map' will need to iterate in more steps because each qcow2_get_cluster_offset() call will potentially return a smaller number. However the code is already prepared for that so this doesn't break semantics. The l2_table variable is also renamed to l2_slice to reflect this, and offset_to_l2_index() is replaced with offset_to_l2_slice_index(). Signed-off-by: NAlberto Garcia <berto@igalia.com> Reviewed-by: NEric Blake <eblake@redhat.com> Reviewed-by: NMax Reitz <mreitz@redhat.com> Message-id: 6b602260acb33da56ed6af9611731cb7acd110eb.1517840877.git.berto@igalia.com Signed-off-by: NMax Reitz <mreitz@redhat.com>
Showing
想要评论请 注册 或 登录