perf: add block cache

Cargo.lock

@@ -2,22 +2,601 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "aarch64-cpu"
+version = "9.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac42a04a61c19fc8196dd728022a784baecc5d63d7e256c01ad1b3fbfab26287"
+dependencies = [
+ "tock-registers",
+]
+
 [[package]]
 name = "another_ext4"
 version = "0.1.0"
 dependencies = [
- "bitflags",
+ "axsync",
+ "bitflags 2.5.0",
+ "log",
+]
+
+[[package]]
+name = "arm_gic"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/arm_gic.git#9aedb126ed0b059ee4e69e032c5e41b593ed10f0"
+dependencies = [
+ "aarch64-cpu",
+ "bitflags 2.5.0",
+ "cfg-if",
+ "tock-registers",
+]
+
+[[package]]
+name = "arm_pl011"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/arm_pl011.git#cba8ce63e6e2248829ae340219e90e6df43cda48"
+dependencies = [
+ "tock-registers",
+]
+
+[[package]]
+name = "autocfg"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c4b4d0bd25bd0b74681c0ad21497610ce1b7c91b1022cd21c80c6fbdd9476b0"
+
+[[package]]
+name = "axconfig"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/axconfig.git#80213038e457bb03e4ac250351d38f58c30debc8"
+dependencies = [
+ "serde",
+ "toml_edit",
+]
+
+[[package]]
+name = "axhal"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/axhal.git#5ac7c72e7a1d2de9219c1fda5a929c90cda59460"
+dependencies = [
+ "aarch64-cpu",
+ "arm_gic",
+ "arm_pl011",
+ "axconfig",
+ "axlog",
+ "bitflags 2.5.0",
+ "cfg-if",
+ "crate_interface",
+ "dw_apb_uart",
+ "either",
+ "handler_table",
+ "kernel_guard",
+ "lazy_init",
+ "log",
+ "memory_addr",
+ "of",
+ "page_table_entry",
+ "percpu",
+ "ratio",
+ "raw-cpuid 11.0.2",
+ "riscv",
+ "sbi-rt",
+ "spinlock",
+ "static_assertions",
+ "taskctx",
+ "tock-registers",
+ "x2apic",
+ "x86",
+ "x86_64",
+]
+
+[[package]]
+name = "axlog"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/axlog.git#5b28a4c6ae14342c725722ef62311ecc0480699c"
+dependencies = [
+ "cfg-if",
+ "crate_interface",
  "log",
+ "spinlock",
 ]
 
+[[package]]
+name = "axsignal"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/axsignal.git#f2e2c4bdea9d903229bbbe7bc93c34cf9a376249"
+dependencies = [
+ "axhal",
+ "bitflags 2.5.0",
+ "cfg-if",
+ "numeric-enum-macro",
+]
+
+[[package]]
+name = "axsync"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/axsync.git#70651a7c8e918e6f6aced3014acfd16f209aa4c0"
+dependencies = [
+ "axhal",
+ "axtask",
+ "cfg-if",
+ "spinlock",
+]
+
+[[package]]
+name = "axtask"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/axtask.git#f8d203f3b99699b64562870cf087a142c3aaec8b"
+dependencies = [
+ "axhal",
+ "axlog",
+ "axsignal",
+ "cfg-if",
+ "linked_list",
+ "log",
+ "numeric-enum-macro",
+ "taskctx",
+]
+
+[[package]]
+name = "bit"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b645c5c09a7d4035949cfce1a915785aaad6f17800c35fda8a8c311c491f284"
+
+[[package]]
+name = "bit_field"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc827186963e592360843fb5ba4b973e145841266c1357f7180c43526f2e5b61"
+
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
 [[package]]
 name = "bitflags"
 version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf4b9d6a944f767f8e5e0db018570623c85f3d925ac718db4e06d0187adb21c1"
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "crate_interface"
+version = "0.1.1"
+source = "git+https://github.com/Starry-OS/crate_interface.git#d27dd9608dbf04b3138cf4386c19f939352b50b0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "critical-section"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7059fff8937831a9ae6f0fe4d658ffabf58f2ca96aa9dec1c889f936f705f216"
+
+[[package]]
+name = "dw_apb_uart"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/dw_apb_uart.git#15d6fb0fe127794598565f2a1188c9dc864ec110"
+dependencies = [
+ "tock-registers",
+]
+
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
+[[package]]
+name = "embedded-hal"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "35949884794ad573cf46071e41c9b60efb0cb311e3ca01f7af807af1debc66ff"
+dependencies = [
+ "nb 0.1.3",
+ "void",
+]
+
+[[package]]
+name = "equivalent"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+
+[[package]]
+name = "fdt"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "784a4df722dc6267a04af36895398f59d21d07dce47232adf31ec0ff2fa45e67"
+
+[[package]]
+name = "handler_table"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/handler_table.git#d6495e7d835cbc999874f0ecf466ee1211447a79"
+
+[[package]]
+name = "hashbrown"
+version = "0.14.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
+
+[[package]]
+name = "indexmap"
+version = "2.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "168fb715dda47215e360912c096649d23d58bf392ac62f73919e831745e40f26"
+dependencies = [
+ "equivalent",
+ "hashbrown",
+]
+
+[[package]]
+name = "kernel_guard"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/kernel_guard.git#72e006721a017db12ce7731fe30f56a83f330216"
+dependencies = [
+ "cfg-if",
+ "taskctx",
+]
+
+[[package]]
+name = "lazy_init"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/lazy_init.git#d0e87c05b715063cc517de50ad5da15b13281def"
+
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+dependencies = [
+ "spin",
+]
+
+[[package]]
+name = "linked_list"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/linked_list.git#01ec54f275fda4ece9741f10d281550c077c0312"
+
+[[package]]
+name = "lock_api"
+version = "0.4.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "07af8b9cdd281b7915f413fa73f29ebd5d55d0d3f0155584dade1ff18cea1b17"
+dependencies = [
+ "autocfg",
+ "scopeguard",
+]
+
 [[package]]
 name = "log"
 version = "0.4.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
+
+[[package]]
+name = "memchr"
+version = "2.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+
+[[package]]
+name = "memory_addr"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/memory_addr.git#a5be547a3109f114994d005b893f9b19c2616709"
+
+[[package]]
+name = "nb"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "801d31da0513b6ec5214e9bf433a77966320625a37860f910be265be6e18d06f"
+dependencies = [
+ "nb 1.1.0",
+]
+
+[[package]]
+name = "nb"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d5439c4ad607c3c23abf66de8c8bf57ba8adcd1f129e699851a6e43935d339d"
+
+[[package]]
+name = "numeric-enum-macro"
+version = "0.2.0"
+source = "git+https://github.com/mexus/numeric-enum-macro#20aef288b2ecd2381ab6627c2a6c9e0436d8c8ff"
+
+[[package]]
+name = "of"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/of.git#a929cf979d9f3dce1547c7ea534bd626fd2f2eda"
+dependencies = [
+ "fdt",
+ "lazy_static",
+]
+
+[[package]]
+name = "page_table_entry"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/page_table_entry.git#b3d8a577c29d19813fbc8c587d86557495099ae3"
+dependencies = [
+ "aarch64-cpu",
+ "bitflags 2.5.0",
+ "memory_addr",
+ "x86_64",
+]
+
+[[package]]
+name = "paste"
+version = "1.0.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57c0d7b74b563b49d38dae00a0c37d4d6de9b432382b2892f0574ddcae73fd0a"
+
+[[package]]
+name = "percpu"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/percpu.git#85e6d8a74f19ac54004e64d42cda07d14042e3ee"
+dependencies = [
+ "cfg-if",
+ "percpu_macros",
+ "spin",
+ "x86",
+]
+
+[[package]]
+name = "percpu_macros"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/percpu_macros.git#b785b814c5489ac7043d80ea4b5a735b23ec2321"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.86"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e719e8df665df0d1c8fbfd238015744736151d4445ec0836b8e628aae103b77"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.36"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "ratio"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/ratio.git#0c8da4c37e695a0052563f0d30909c9f29b5b572"
+
+[[package]]
+name = "raw-cpuid"
+version = "10.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c297679cb867470fa8c9f67dbba74a78d78e3e98d7cf2b08d6d71540f797332"
+dependencies = [
+ "bitflags 1.3.2",
+]
+
+[[package]]
+name = "raw-cpuid"
+version = "11.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e29830cbb1290e404f24c73af91c5d8d631ce7e128691e9477556b540cd01ecd"
+dependencies = [
+ "bitflags 2.5.0",
+]
+
+[[package]]
+name = "riscv"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa3145d2fae3778b1e31ec2e827b228bdc6abd9b74bb5705ba46dcb82069bc4f"
+dependencies = [
+ "bit_field",
+ "critical-section",
+ "embedded-hal",
+]
+
+[[package]]
+name = "rustversion"
+version = "1.0.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "955d28af4278de8121b7ebeb796b6a45735dc01436d898801014aced2773a3d6"
+
+[[package]]
+name = "sbi-rt"
+version = "0.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8c113c53291db8ac141e01f43224ed488b8d6001ab66737b82e04695a43a42b7"
+dependencies = [
+ "sbi-spec",
+]
+
+[[package]]
+name = "sbi-spec"
+version = "0.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6d4027cf9bb591a9fd0fc0e283be6165c5abe96cb73e9f0e24738c227f425377"
+dependencies = [
+ "static_assertions",
+]
+
+[[package]]
+name = "scopeguard"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
+
+[[package]]
+name = "serde"
+version = "1.0.203"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7253ab4de971e72fb7be983802300c30b5a7f0c2e56fab8abfc6a214307c0094"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.203"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "500cbc0ebeb6f46627f50f3f5811ccf6bf00643be300b4c3eabc0ef55dc5b5ba"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "spin"
+version = "0.9.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
+dependencies = [
+ "lock_api",
+]
+
+[[package]]
+name = "spinlock"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/spinlock.git#0149e52d3e4f21ea7bf9bb85f6fe7fc3702d4f1f"
+dependencies = [
+ "cfg-if",
+ "kernel_guard",
+]
+
+[[package]]
+name = "static_assertions"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
+
+[[package]]
+name = "syn"
+version = "2.0.68"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "901fa70d88b9d6c98022e23b4136f9f3e54e4662c3bc1bd1d84a42a9a0f0c1e9"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "taskctx"
+version = "0.1.0"
+source = "git+https://github.com/Starry-OS/taskctx.git#86561d9659f294328350d0235e8f5d285fd6e766"
+dependencies = [
+ "aarch64-cpu",
+ "cfg-if",
+ "log",
+ "memory_addr",
+ "numeric-enum-macro",
+ "static_assertions",
+ "tock-registers",
+ "x86",
+]
+
+[[package]]
+name = "tock-registers"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "696941a0aee7e276a165a978b37918fd5d22c55c3d6bda197813070ca9c0f21c"
+
+[[package]]
+name = "toml_datetime"
+version = "0.6.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4badfd56924ae69bcc9039335b2e017639ce3f9b001c393c1b2d1ef846ce2cbf"
+
+[[package]]
+name = "toml_edit"
+version = "0.19.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b5bb770da30e5cbfde35a2d7b9b8a2c4b8ef89548a7a6aeab5c9a576e3e7421"
+dependencies = [
+ "indexmap",
+ "toml_datetime",
+ "winnow",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
+
+[[package]]
+name = "void"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a02e4885ed3bc0f2de90ea6dd45ebcbb66dacffe03547fadbb0eeae2770887d"
+
+[[package]]
+name = "volatile"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "442887c63f2c839b346c192d047a7c87e73d0689c9157b00b53dcc27dd5ea793"
+
+[[package]]
+name = "winnow"
+version = "0.5.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f593a95398737aeed53e489c785df13f3618e41dbcd6718c6addbf1395aa6876"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "x2apic"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cbcd582541cbb8ef1dfc24a3c849a64ff074b1b512af723ad90056558d424602"
+dependencies = [
+ "bit",
+ "bitflags 1.3.2",
+ "paste",
+ "raw-cpuid 10.7.0",
+ "x86_64",
+]
+
+[[package]]
+name = "x86"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2781db97787217ad2a2845c396a5efe286f87467a5810836db6d74926e94a385"
+dependencies = [
+ "bit_field",
+ "bitflags 1.3.2",
+ "raw-cpuid 10.7.0",
+]
+
+[[package]]
+name = "x86_64"
+version = "0.14.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96cb6fd45bfeab6a5055c5bffdb08768bd0c069f1d946debe585bbb380a7c062"
+dependencies = [
+ "bit_field",
+ "bitflags 2.5.0",
+ "rustversion",
+ "volatile",
+]

Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 [dependencies]
 bitflags = "2.2.1"
 log = "0.4"
+axsync = { git = "https://github.com/Starry-OS/axsync.git" }

src/constants.rs

@@ -36,3 +36,9 @@ pub const SB_GOOD_INODE_SIZE: usize = 256;
 /// The value of super block `desc_size` field.
 /// We implement the 64-bit block group descriptor for simplicity.
 pub const SB_GOOD_DESC_SIZE: usize = 64;
+
+/// The size of the block cache (cache set number).
+pub const CACHE_SIZE: usize = 4;
+
+/// Cache associativity.
+pub const CACHE_ASSOC: usize = 4;

src/ext4/mod.rs

@@ -13,7 +13,7 @@ mod low_level;
 mod rw;
 
 pub struct Ext4 {
-    block_device: Arc<dyn BlockDevice>,
+    block_cache: BlockCache,
 }
 
 impl Ext4 {
@@ -41,7 +41,9 @@ impl Ext4 {
             );
         }
         // Create Ext4 instance
-        Ok(Self { block_device })
+        Ok(Self {
+            block_cache: BlockCache::new(block_device),
+        })
     }
     /// Initializes the root directory.
     pub fn init(&mut self) -> Result<()> {

src/ext4/rw.rs

@@ -1,18 +1,17 @@
 use crate::constants::*;
 use crate::ext4_defs::*;
 use crate::prelude::*;
-
 use super::Ext4;
 
 impl Ext4 {
     /// Read a block from block device
     pub(super) fn read_block(&self, block_id: PBlockId) -> Block {
-        self.block_device.read_block(block_id)
+        self.block_cache.read_block(block_id)
     }
 
     /// Write a block to block device
     pub(super) fn write_block(&self, block: &Block) {
-        self.block_device.write_block(block)
+        self.block_cache.write_block(block)
     }
 
     /// Read super block from block device
@@ -26,7 +25,7 @@ impl Ext4 {
     pub(super) fn write_super_block(&self, sb: &SuperBlock) {
         let mut block = Block::new(0, [0; BLOCK_SIZE]);
         block.write_offset_as(BASE_OFFSET, sb);
-        self.block_device.write_block(&block)
+        self.write_block(&block)
     }
 
     /// Read an inode from block device, return an `InodeRef` that

src/ext4_defs/block_device.rs → src/ext4_defs/block.rs

@@ -24,6 +24,7 @@ where
 }
 
 /// Common data block descriptor.
+#[derive(Debug, Clone, Copy)]
 pub struct Block {
     /// Physical block id
     pub id: PBlockId,

src/ext4_defs/cache.rs

@@ -0,0 +1,146 @@
+use crate::constants::*;
+use crate::prelude::*;
+use crate::Block;
+use crate::BlockDevice;
+
+/// Write-back cache slot.
+#[derive(Debug, Clone, Copy, Default)]
+struct CacheSlot {
+    /// Valid flag.
+    valid: bool,
+    /// Dirty flag.
+    dirty: bool,
+    /// Previous slot in the LRU list.
+    prev: u8,
+    /// Next slot in the LRU list.
+    next: u8,
+    /// Block data.
+    block: Block,
+}
+
+/// Associative cache set.
+#[derive(Debug, Clone, Copy)]
+struct CacheSet {
+    /// `CACHE_ASSOC`-way-associative slots.
+    slots: [CacheSlot; CACHE_ASSOC],
+    /// Head of the LRU list.
+    head: u8,
+}
+
+impl CacheSet {
+    /// Initialize the cache set. Initialize in heap to avoid stack overflow.
+    fn new() -> Box<Self> {
+        let mut set = Box::new(CacheSet {
+            slots: [CacheSlot::default(); CACHE_ASSOC],
+            head: CACHE_ASSOC as u8 - 1,
+        });
+        for i in 1..CACHE_ASSOC as u8 {
+            set.link(i - 1, i);
+        }
+        set.link(CACHE_ASSOC as u8 - 1, 0);
+        set
+    }
+
+    /// Link LRU list.
+    fn link(&mut self, prev: u8, cur: u8) {
+        self.slots[prev as usize].next = cur;
+        self.slots[cur as usize].prev = prev;
+    }
+
+    /// Access a block in the cache set
+    fn access(&mut self, block_id: PBlockId) -> usize {
+        // Check if there is a slot allocated for the block
+        let slot = self
+            .slots
+            .iter()
+            .position(|b| b.valid && b.block.id == block_id);
+        if let Some(slot) = slot {
+            // If yes, set head as slot_id
+            if self.head != slot as u8 {
+                self.link(self.slots[slot].prev, self.slots[slot].next);
+                self.link(self.slots[self.head as usize].prev, slot as u8);
+                self.link(slot as u8, self.head);
+                self.head = slot as u8;
+            }
+            slot
+        } else {
+            // If not, head goes 1 step forward to reach the last slot
+            self.head = self.slots[self.head as usize].prev;
+            self.head as usize
+        }
+    }
+}
+
+/// LRU Write-back Block Cache.
+pub struct BlockCache {
+    /// Block cache allocated on the heap.
+    cache: Arc<Mutex<[CacheSet; CACHE_SIZE]>>,
+    /// The underlying block device.
+    block_dev: Arc<dyn BlockDevice>,
+}
+
+impl BlockCache {
+    /// Create a new block cache on a block device.
+    pub fn new(block_dev: Arc<dyn BlockDevice>) -> Self {
+        // Initialize in heap to avoid stack overflow
+        let cache = vec![*CacheSet::new(); CACHE_SIZE];
+        Self {
+            cache: Arc::new(Mutex::new(cache.try_into().unwrap())),
+            block_dev,
+        }
+    }
+
+    /// Read a block.
+    pub fn read_block(&self, block_id: PBlockId) -> Block {
+        debug!("Reading block {}", block_id);
+        let set_id = block_id as usize % CACHE_SIZE;
+        let mut cache = self.cache.lock();
+        let slot_id = cache[set_id].access(block_id) as usize;
+        let slot = &mut cache[set_id].slots[slot_id];
+        // Check block id
+        if slot.valid && slot.block.id == block_id {
+            // Cache hit
+            return slot.block.clone();
+        } else {
+            // Cache miss
+            if slot.valid && slot.dirty {
+                // Write back Dirty block
+                self.block_dev.write_block(&slot.block);
+                slot.dirty = false;
+            }
+            // Read block from disk
+            debug!("Loading block {} from disk", block_id);
+            let block = self.block_dev.read_block(block_id);
+            slot.block = block.clone();
+            slot.valid = true;
+            return block;
+        }
+    }
+
+    /// Write a block. (Write-Allocate)
+    pub fn write_block(&self, block: &Block) {
+        debug!("Writing block {}", block.id);
+        let set_id = block.id as usize % CACHE_SIZE;
+        let mut cache = self.cache.lock();
+        let slot_id = cache[set_id].access(block.id) as usize;
+        let slot = &mut cache[set_id].slots[slot_id];
+        // Check block id
+        if slot.valid && slot.block.id == block.id {
+            // Cache hit
+            slot.block = block.clone();
+            slot.dirty = true;
+        } else {
+            // Cache miss
+            if slot.valid && slot.dirty {
+                // Write back Dirty block
+                self.block_dev.write_block(&slot.block);
+                slot.dirty = false;
+            }
+            // Write allocate
+            let block = self.block_dev.read_block(block.id);
+            slot.block = block.clone();
+            slot.valid = true;
+            slot.dirty = true;
+        }
+    }
+}

src/ext4_defs/mod.rs

@@ -15,8 +15,9 @@
 //! For all other block groups, there is no padding.
 
 mod bitmap;
-mod block_device;
+mod block;
 mod block_group;
+mod cache;
 mod crc;
 mod dir;
 mod extent;
@@ -27,8 +28,9 @@ mod super_block;
 mod xattr;
 
 pub use bitmap::*;
-pub use block_device::*;
+pub use block::*;
 pub use block_group::*;
+pub use cache::*;
 pub use dir::*;
 pub use extent::*;
 pub use file::*;

src/prelude.rs

@@ -23,6 +23,7 @@ pub(crate) use core::ffi::CStr;
 pub(crate) use core::fmt::Debug;
 pub(crate) use core::mem::{self, size_of};
 pub(crate) use core::ptr;
+pub(crate) use axsync::Mutex;
 
 pub(crate) use log::{debug, info, trace, warn};