2024-06-01 14:24:45

by Keith Busch

Subject: Re: [PATCH v4 2/3] rust: block: add rnull, Rust null_blk implementation

On Sat, Jun 01, 2024 at 03:40:04PM +0200, Andreas Hindborg wrote:
> +impl kernel::Module for NullBlkModule {
> + fn init(_module: &'static ThisModule) -> Result<Self> {
> + pr_info!("Rust null_blk loaded\n");
> + let tagset = Arc::pin_init(TagSet::try_new(1, 256, 1), flags::GFP_KERNEL)?;
> +
> + let disk = {
> + let block_size: u16 = 4096;
> + if block_size % 512 != 0 || !(512..=4096).contains(&block_size) {
> + return Err(kernel::error::code::EINVAL);
> + }

You've set block_size to the literal 4096, then validate its value
immediately after? Am I missing some way this could ever be invalid?

2024-06-01 18:42:02

by Andreas Hindborg

Subject: Re: [PATCH v4 2/3] rust: block: add rnull, Rust null_blk implementation

Keith Busch <[email protected]> writes:

> On Sat, Jun 01, 2024 at 03:40:04PM +0200, Andreas Hindborg wrote:
>> +impl kernel::Module for NullBlkModule {
>> + fn init(_module: &'static ThisModule) -> Result<Self> {
>> + pr_info!("Rust null_blk loaded\n");
>> + let tagset = Arc::pin_init(TagSet::try_new(1, 256, 1), flags::GFP_KERNEL)?;
>> +
>> + let disk = {
>> + let block_size: u16 = 4096;
>> + if block_size % 512 != 0 || !(512..=4096).contains(&block_size) {
>> + return Err(kernel::error::code::EINVAL);
>> + }
>
> You've set block_size to the literal 4096, then validate its value
> immediately after? Am I missing some way this could ever be invalid?

Good catch. It is because I have a patch in the outbound queue that allows setting
the block size via a module parameter. The module parameter patch is not
upstream yet. Once I have that up, I will send the patch with the block
size config.

Do you think it is OK to have this redundancy? It would only be for a
few cycles.

Best regards,
Andreas