block: Improve errors about block sizes

block: Improve errors about block sizes

Block sizes need to be a power of two between 512 and an arbitrary
limit, currently 2MiB.

Commit 5937835ac4c factored block size checking out of set_blocksize()
into new check_block_size(), for reuse in block/export/.

Its two error messages are okay for the original purpose:

    $ qemu-system-x86_64 -device ide-hd,physical_block_size=1
    qemu-system-x86_64: -device ide-hd,physical_block_size=1: Property .physical_block_size doesn't take value 1 (minimum: 512, maximum: 2097152)
    $ qemu-system-x86_64 -device ide-hd,physical_block_size=513
    qemu-system-x86_64: -device ide-hd,physical_block_size=513: Property .physical_block_size doesn't take value '513', it's not a power of 2

They're mildly off for block exports:

    $ qemu-storage-daemon --blockdev node-name=nod0,driver=file,filename=foo.img --export type=vduse-blk,id=exp0,node-name=nod0,name=foo,logical-block-size=1
    qemu-storage-daemon: --export type=vduse-blk,id=exp0,node-name=nod0,name=foo,logical-block-size=1: Property exp0.logical-block-size doesn't take value 1 (minimum: 512, maximum: 2097152)

The error message talks about a property.  CLI options like --export
don't have properties, they have parameters.

Replace the two error messages by a single one that's okay for both
purposes.  Looks like this:

    qemu-storage-daemon: --export type=vduse-blk,id=exp0,node-name=nod0,name=foo,logical-block-size=1: parameter logical-block-size must be a power of 2 between 512 and 2097152

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20241010150144.986655-3-armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>