Re: [PATCH v9 7/9] rust: id_pool: add contiguous ID reservation

[Yury Norov <ynorov@nvidia.com>]

On Wed, Sep 30, 2026 at 11:42:56AM +0900, Eliot Courtney wrote:
> Add `IdPool::reserve_ids` which allocates a contiguous range with the
> given offset, count, and alignment.
> 
> Reviewed-by: Burak Emir <burak.emir@gmail.com>
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>

Reviewed-by: Yury Norov <ynorov@nvidia.com>

> ---
>  rust/kernel/id_pool.rs | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/rust/kernel/id_pool.rs b/rust/kernel/id_pool.rs
> index 384753fe0e44..06a4c71c4c6c 100644
> --- a/rust/kernel/id_pool.rs
> +++ b/rust/kernel/id_pool.rs
> @@ -4,8 +4,14 @@
>  
>  //! Rust API for an ID pool backed by a [`BitmapVec`].
>  
> +use core::{
> +    num::NonZero,
> +    ops::Range, //
> +};
> +
>  use crate::alloc::{AllocError, Flags};
>  use crate::bitmap::BitmapVec;
> +use crate::ptr::Alignment;
>  
>  /// Represents a dynamic ID pool backed by a [`BitmapVec`].
>  ///
> @@ -240,6 +246,32 @@ pub fn find_unused_id(&mut self, offset: usize) -> Option<UnusedId<'_>> {
>      pub fn release_id(&mut self, id: usize) {
>          self.map.clear_bit(id);
>      }
> +
> +    /// Reserves a contiguous area of `count` IDs at or after `offset`.
> +    ///
> +    /// The start of the returned area is a multiple of `align`.
> +    ///
> +    /// Returns the reserved range upon success, or [`None`] if no such area could be found.
> +    #[inline]
> +    #[must_use]
> +    pub fn reserve_ids(
> +        &mut self,
> +        offset: usize,
> +        count: NonZero<usize>,
> +        align: Alignment,
> +    ) -> Option<Range<usize>> {
> +        let start = self.map.next_zero_area(offset, count, align)?;
> +        self.map.set(start, count);
> +        Some(start..start + count.get())
> +    }
> +
> +    /// Releases a contiguous area of IDs.
> +    #[inline]
> +    pub fn release_ids(&mut self, range: &Range<usize>) {
> +        if let Some(nbits) = NonZero::new(range.len()) {
> +            self.map.clear(range.start, nbits);
> +        }
> +    }
>  }
>  
>  /// Represents an unused id in an [`IdPool`].
> 
> -- 
> 2.55.0