Derives Pod for tiered storage types (#34414)

accounts-db/src/tiered_storage/footer.rs

@@ -29,6 +29,9 @@ pub const FOOTER_MAGIC_NUMBER: u64 = 0x502A2AB5; // SOLALABS -> SOLANA LABS
 #[repr(C)]
 pub struct TieredStorageMagicNumber(pub u64);
 
+// Ensure there are no implicit padding bytes
+const _: () = assert!(std::mem::size_of::<TieredStorageMagicNumber>() == 8);
+
 impl Default for TieredStorageMagicNumber {
     fn default() -> Self {
         Self(FOOTER_MAGIC_NUMBER)

accounts-db/src/tiered_storage/hot.rs

@@ -15,6 +15,7 @@ use {
             TieredStorageError, TieredStorageFormat, TieredStorageResult,
         },
     },
+    bytemuck::{Pod, Zeroable},
     memmap2::{Mmap, MmapOptions},
     modular_bitfield::prelude::*,
     solana_sdk::{pubkey::Pubkey, stake_history::Epoch},
@@ -47,7 +48,7 @@ const MAX_HOT_ACCOUNT_OFFSET: usize = u32::MAX as usize * HOT_ACCOUNT_ALIGNMENT;
 
 #[bitfield(bits = 32)]
 #[repr(C)]
-#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
+#[derive(Debug, Default, Copy, Clone, Eq, PartialEq, Pod, Zeroable)]
 struct HotMetaPackedFields {
     /// A hot account entry consists of the following elements:
     ///
@@ -63,11 +64,17 @@ struct HotMetaPackedFields {
     owner_offset: B29,
 }
 
+// Ensure there are no implicit padding bytes
+const _: () = assert!(std::mem::size_of::<HotMetaPackedFields>() == 4);
+
 /// The offset to access a hot account.
 #[repr(C)]
-#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
+#[derive(Debug, Default, Copy, Clone, Eq, PartialEq, Pod, Zeroable)]
 pub struct HotAccountOffset(u32);
 
+// Ensure there are no implicit padding bytes
+const _: () = assert!(std::mem::size_of::<HotAccountOffset>() == 4);
+
 impl AccountOffset for HotAccountOffset {}
 
 impl HotAccountOffset {
@@ -99,7 +106,7 @@ impl HotAccountOffset {
 
 /// The storage and in-memory representation of the metadata entry for a
 /// hot account.
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Pod, Zeroable)]
 #[repr(C)]
 pub struct HotAccountMeta {
     /// The balance of this account.
@@ -110,6 +117,9 @@ pub struct HotAccountMeta {
     flags: AccountMetaFlags,
 }
 
+// Ensure there are no implicit padding bytes
+const _: () = assert!(std::mem::size_of::<HotAccountMeta>() == 8 + 4 + 4);
+
 impl TieredAccountMeta for HotAccountMeta {
     /// Construct a HotAccountMeta instance.
     fn new() -> Self {

accounts-db/src/tiered_storage/index.rs

@@ -3,6 +3,7 @@ use {
         file::TieredStorageFile, footer::TieredStorageFooter, mmap_utils::get_type,
         TieredStorageResult,
     },
+    bytemuck::{Pod, Zeroable},
     memmap2::Mmap,
     solana_sdk::pubkey::Pubkey,
 };
@@ -17,14 +18,18 @@ pub struct AccountIndexWriterEntry<'a, Offset: AccountOffset> {
 }
 
 /// The offset to an account.
-pub trait AccountOffset {}
+pub trait AccountOffset: Clone + Copy + Pod + Zeroable {}
 
 /// The offset to an account/address entry in the accounts index block.
 /// This can be used to obtain the AccountOffset and address by looking through
 /// the accounts index block.
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[repr(C)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Pod, Zeroable)]
 pub struct IndexOffset(pub u32);
 
+// Ensure there are no implicit padding bytes
+const _: () = assert!(std::mem::size_of::<IndexOffset>() == 4);
+
 /// The index format of a tiered accounts file.
 #[repr(u16)]
 #[derive(
@@ -46,6 +51,9 @@ pub enum IndexBlockFormat {
     AddressAndBlockOffsetOnly = 0,
 }
 
+// Ensure there are no implicit padding bytes
+const _: () = assert!(std::mem::size_of::<IndexBlockFormat>() == 2);
+
 impl IndexBlockFormat {
     /// Persists the specified index_entries to the specified file and returns
     /// the total number of bytes written.
@@ -86,7 +94,7 @@ impl IndexBlockFormat {
     }
 
     /// Returns the offset to the account given the specified index.
-    pub fn get_account_offset<Offset: AccountOffset + Copy>(
+    pub fn get_account_offset<Offset: AccountOffset>(
         &self,
         mmap: &Mmap,
         footer: &TieredStorageFooter,

accounts-db/src/tiered_storage/meta.rs

@@ -2,6 +2,7 @@
 
 use {
     crate::{accounts_hash::AccountHash, tiered_storage::owners::OwnerOffset},
+    bytemuck::{Pod, Zeroable},
     modular_bitfield::prelude::*,
     solana_sdk::stake_history::Epoch,
 };
@@ -9,7 +10,7 @@ use {
 /// The struct that handles the account meta flags.
 #[bitfield(bits = 32)]
 #[repr(C)]
-#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
+#[derive(Debug, Default, Copy, Clone, Eq, PartialEq, Pod, Zeroable)]
 pub struct AccountMetaFlags {
     /// whether the account meta has rent epoch
     pub has_rent_epoch: bool,
@@ -19,6 +20,9 @@ pub struct AccountMetaFlags {
     reserved: B30,
 }
 
+// Ensure there are no implicit padding bytes
+const _: () = assert!(std::mem::size_of::<AccountMetaFlags>() == 4);
+
 /// A trait that allows different implementations of the account meta that
 /// support different tiers of the accounts storage.
 pub trait TieredAccountMeta: Sized {