"-S 0" for "qemu-img convert" now works correctly
Previously, specifying the "-S 0" option with "qemu-img convert" did not always explicitly write zeroes to all sparse areas in the output file. As a result, running "qemu-img convert -S 0" did not always result in a fully allocated output file. With this update, the command has been fixed, and running "qemu-img convert -S 0" always results in a fully allocated output file.
Note that the qcow2 format offers a different preallocation option which can convert images to fully allocated output files faster than using the "-S 0" option. However, with other formats, this can only be achieved with the "-S 0" option.