P10 write fs

Makefile

@@ -69,16 +69,22 @@ xv6.img: bootblock kernel
 	dd if=bootblock of=xv6.img conv=notrunc
 	dd if=kernel of=xv6.img seek=1 conv=notrunc
 
+mkfs: ../col331/mkfs.c ../col331/fs.h ../col331/types.h ../col331/stat.h ../col331/param.h
+	gcc -Werror -Wall -o mkfs ../col331/mkfs.c
+
+fs.img: mkfs welcome.txt
+	./mkfs fs.img welcome.txt
+
 bootblock: bootasm.S bootmain.c
 	$(CC) $(CFLAGS) -fno-pic -O -nostdinc -I. -c bootmain.c
 	$(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c bootasm.S
 	$(LD) $(LDFLAGS) -N -e start -Ttext 0x7C00 -o bootblock.o bootasm.o bootmain.o
 	$(OBJDUMP) -S -D bootblock.o > bootblock.asm
 	$(OBJCOPY) -S -O binary -j .text bootblock.o bootblock
-	./sign.pl bootblock
+	perl sign.pl bootblock
 
 kernel.a: $(RS)
-	cargo rustc -Z build-std=core -Z build-std-features=compiler-builtins-mem --target ./targets/i686.json --lib --release -- -A warnings --emit link=kernel.a
+	cargo rustc -Z build-std=core -Z build-std-features=compiler-builtins-mem -Z json-target-spec --target ./targets/i686.json --lib --release -- -A warnings --emit link=kernel.a
 
 kernel: kernel.a $(OBJS) ./linkers/kernel.ld
 	ld -m elf_i386 -T ./linkers/kernel.ld -o kernel $(OBJS) kernel.a
@@ -100,12 +106,12 @@ vectors.S: vectors.pl
 
 clean: 
 	rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \
-	*.a *.o *.d *.asm *.sym bootblock kernel xv6.img .gdbinit vectors.S
-	rm -r target
+	*.a *.o *.d *.asm *.sym bootblock kernel xv6.img fs.img .gdbinit vectors.S mkfs
+	rm -rf target
 
 # run in emulators
 # try to generate a unique GDB port
-GDBPORT = $(shell expr `id -u` % 5000 + 25000)
+GDBPORT = $(shell expr `id -u` % 5000 + 25001)
 # QEMU's gdb stub command line changed in 0.11
 QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
 	then echo "-gdb tcp::$(GDBPORT)"; \
@@ -116,14 +122,14 @@ endif
 
 # For debugging
 # QEMUEXTRA = -no-reboot -d int,cpu_reset
-QEMUOPTS = -drive file=xv6.img,index=0,media=disk,format=raw -smp $(CPUS) -m 512 $(QEMUEXTRA)
+QEMUOPTS = -drive file=xv6.img,index=0,media=disk,format=raw -drive file=fs.img,index=1,media=disk,format=raw -smp $(CPUS) -m 512 $(QEMUEXTRA)
 
-qemu: xv6.img
+qemu: xv6.img fs.img
 	$(QEMU) -nographic $(QEMUOPTS)
 
 .gdbinit: .gdbinit.tmpl
 	sed "s/localhost:1234/localhost:$(GDBPORT)/" < $^ > $@
 
-qemu-gdb: xv6.img .gdbinit
+qemu-gdb: xv6.img .gdbinit fs.img
 	@echo "*** Now run 'gdb'." 1>&2
-	$(QEMU) -nographic $(QEMUOPTS) -S $(QEMUGDB)
+	$(QEMU) -nographic $(QEMUOPTS) -S $(QEMUGDB)

src/Makefile

@@ -0,0 +1,130 @@
+OBJS = entry.o vectors.o trapasm.o
+RS = src/*.rs
+
+# Cross-compiling (e.g., on Mac OS X)
+#TOOLPREFIX = i386-jos-elf
+#TOOLPREFIX = i386-elf-
+
+# Using native tools (e.g., on X86 Linux)
+#TOOLPREFIX =
+
+# Try to infer the correct TOOLPREFIX if not set
+ifndef TOOLPREFIX
+TOOLPREFIX := $(shell if i386-jos-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
+	then echo 'i386-jos-elf-'; \
+	elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
+	then echo ''; \
+	else echo "***" 1>&2; \
+	echo "*** Error: Couldn't find an i386-*-elf version of GCC/binutils." 1>&2; \
+	echo "*** Is the directory with i386-jos-elf-gcc in your PATH?" 1>&2; \
+	echo "*** If your i386-*-elf toolchain is installed with a command" 1>&2; \
+	echo "*** prefix other than 'i386-jos-elf-', set your TOOLPREFIX" 1>&2; \
+	echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
+	echo "*** To turn off this error, run 'gmake TOOLPREFIX= ...'." 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# If the makefile can't find QEMU, specify its path here
+# QEMU = qemu-system-i386
+
+# Try to infer the correct QEMU
+ifndef QEMU
+QEMU = $(shell if which qemu > /dev/null; \
+	then echo qemu; exit; \
+	elif which qemu-system-i386 > /dev/null; \
+	then echo qemu-system-i386; exit; \
+	elif which qemu-system-x86_64 > /dev/null; \
+	then echo qemu-system-x86_64; exit; \
+	else \
+	qemu=/Applications/Q.app/Contents/MacOS/i386-softmmu.app/Contents/MacOS/i386-softmmu; \
+	if test -x $$qemu; then echo $$qemu; exit; fi; fi; \
+	echo "***" 1>&2; \
+	echo "*** Error: Couldn't find a working QEMU executable." 1>&2; \
+	echo "*** Is the directory containing the qemu binary in your PATH" 1>&2; \
+	echo "*** or have you tried setting the QEMU variable in Makefile?" 1>&2; \
+	echo "***" 1>&2; exit 1)
+endif
+
+CC = $(TOOLPREFIX)gcc
+AS = $(TOOLPREFIX)gas
+LD = $(TOOLPREFIX)ld
+OBJCOPY = $(TOOLPREFIX)objcopy
+OBJDUMP = $(TOOLPREFIX)objdump
+CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -O2 -Wall -MD -ggdb -m32 -Werror -fno-omit-frame-pointer
+CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
+ASFLAGS = -m32 -gdwarf-2 -Wa,-divide
+LDFLAGS += -m $(shell $(LD) -V | grep elf_i386 2>/dev/null | head -n 1)
+
+# Disable PIE when possible (for Ubuntu 16.10 toolchain)
+ifneq ($(shell $(CC) -dumpspecs 2>/dev/null | grep -e '[^f]no-pie'),)
+CFLAGS += -fno-pie -no-pie
+endif
+ifneq ($(shell $(CC) -dumpspecs 2>/dev/null | grep -e '[^f]nopie'),)
+CFLAGS += -fno-pie -nopie
+endif
+
+# Disk image with bootblock + kernel
+xv6.img: bootblock kernel
+	dd if=/dev/zero of=xv6.img count=10000
+	dd if=bootblock of=xv6.img conv=notrunc
+	dd if=kernel of=xv6.img seek=1 conv=notrunc
+
+mkfs: ../../col331/mkfs.c ../../col331/fs.h ../../col331/types.h ../../col331/stat.h ../../col331/param.h
+	gcc -Werror -Wall -o mkfs ../../col331/mkfs.c
+
+fs: fs.img
+
+fs.img: mkfs ../welcome.txt
+	./mkfs fs.img ../welcome.txt
+
+bootblock: bootasm.S bootmain.c
+	$(CC) $(CFLAGS) -fno-pic -O -nostdinc -I. -c bootmain.c
+	$(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c bootasm.S
+	$(LD) $(LDFLAGS) -N -e start -Ttext 0x7C00 -o bootblock.o bootasm.o bootmain.o
+	$(OBJDUMP) -S -D bootblock.o > bootblock.asm
+	$(OBJCOPY) -S -O binary -j .text bootblock.o bootblock
+	perl sign.pl bootblock
+
+kernel.a: $(RS)
+	cargo rustc -Z build-std=core -Z build-std-features=compiler-builtins-mem -Z json-target-spec --target ./targets/i686.json --lib --release -- -A warnings --emit link=kernel.a
+
+
+kernel: kernel.a $(OBJS) ./linkers/kernel.ld
+	ld -m elf_i386 -T ./linkers/kernel.ld -o kernel $(OBJS) kernel.a
+	$(OBJDUMP) -S -D kernel > kernel.asm
+	$(OBJDUMP) -t kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernel.sym
+
+vectors.S: vectors.pl
+	./vectors.pl > vectors.S
+
+.PRECIOUS: %.o
+-include *.d
+
+clean:
+	rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \
+	*.a *.o *.d *.asm *.sym bootblock kernel xv6.img fs.img .gdbinit vectors.S mkfs
+	rm -rf target
+
+# run in emulators
+GDBPORT = $(shell expr `id -u` % 5000 + 25000)
+QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
+	then echo "-gdb tcp::$(GDBPORT)"; \
+	else echo "-s -p $(GDBPORT)"; fi)
+ifndef CPUS
+	CPUS := 1
+endif
+
+# Attach fs.img as disk1 (index=1), like the C version
+QEMUOPTS = -drive file=xv6.img,index=0,media=disk,format=raw \
+           -drive file=fs.img,index=1,media=disk,format=raw \
+           -smp $(CPUS) -m 512 $(QEMUEXTRA)
+
+qemu: xv6.img fs.img
+	$(QEMU) -nographic $(QEMUOPTS)
+
+.gdbinit: .gdbinit.tmpl
+	sed "s/localhost:1234/localhost:$(GDBPORT)/" < $^ > $@
+
+qemu-gdb: xv6.img fs .gdbinit
+	@echo "*** Now run 'gdb'." 1>&2
+	$(QEMU) -nographic $(QEMUOPTS) -S $(QEMUGDB)

src/bio.rs

@@ -0,0 +1,148 @@
+use core::sync::atomic::Ordering;
+
+use crate::buf::{Buf, B_DIRTY, B_VALID, NBUF};
+
+const HEAD: usize = NBUF; // sentinel index
+
+struct BCache {
+    buf: [Buf; NBUF],
+    head_prev: usize,
+    head_next: usize,
+}
+
+impl BCache {
+    pub const fn new() -> Self {
+        Self {
+            buf: [const { Buf::new() }; NBUF],
+            head_prev: HEAD,
+            head_next: HEAD,
+        }
+    }
+}
+
+static mut BCACHE: BCache = BCache::new();
+
+pub fn binit() {
+    unsafe {
+        // empty list
+        BCACHE.head_prev = HEAD;
+        BCACHE.head_next = HEAD;
+
+        // insert all buffers at head (MRU side)
+        for i in 0..NBUF {
+            insert_at_head(i);
+        }
+    }
+}
+
+#[inline]
+fn insert_at_head(i: usize) {
+    unsafe {
+        let first = BCACHE.head_next;
+
+        BCACHE.buf[i].prev = HEAD;
+        BCACHE.buf[i].next = first;
+
+        if first == HEAD {
+            // list was empty
+            BCACHE.head_prev = i;
+        } else {
+            BCACHE.buf[first].prev = i;
+        }
+
+        BCACHE.head_next = i;
+    }
+}
+
+#[inline]
+fn remove_from_list(i: usize) {
+    unsafe {
+        let prev = BCACHE.buf[i].prev;
+        let next = BCACHE.buf[i].next;
+
+        if prev == HEAD {
+            BCACHE.head_next = next;
+        } else {
+            BCACHE.buf[prev].next = next;
+        }
+
+        if next == HEAD {
+            BCACHE.head_prev = prev;
+        } else {
+            BCACHE.buf[next].prev = prev;
+        }
+    }
+}
+
+// Return mutable buf by index.
+// Safe to call only when you “own” the buffer logically (like xv6 “locked buf”).
+pub fn buf_mut(idx: usize) -> &'static mut Buf {
+    unsafe { &mut BCACHE.buf[idx] }
+}
+
+// Look for cached block; else recycle an unused non-dirty buffer.
+fn bget(dev: u32, blockno: u32) -> usize {
+    unsafe {
+        // Is the block already cached?
+        let mut b = BCACHE.head_next;
+        while b != HEAD {
+            if BCACHE.buf[b].dev == dev && BCACHE.buf[b].blockno == blockno {
+                BCACHE.buf[b].refcnt += 1;
+                return b;
+            }
+            b = BCACHE.buf[b].next;
+        }
+
+        // Not cached; recycle from LRU end.
+        let mut b = BCACHE.head_prev;
+        while b != HEAD {
+            let flags = BCACHE.buf[b].flags.load(Ordering::Acquire);
+            if BCACHE.buf[b].refcnt == 0 && (flags & B_DIRTY) == 0 {
+                BCACHE.buf[b].dev = dev;
+                BCACHE.buf[b].blockno = blockno;
+                BCACHE.buf[b].flags.store(0, Ordering::Release);
+                BCACHE.buf[b].refcnt = 1;
+                BCACHE.buf[b].qnext = None;
+                return b;
+            }
+            b = BCACHE.buf[b].prev;
+        }
+
+        panic!("bget: no buffers");
+    }
+}
+
+// Return buffer index with contents of block.
+pub fn bread(dev: u32, blockno: u32) -> usize {
+    let idx = bget(dev, blockno);
+
+    let flags = buf_mut(idx).flags.load(Ordering::Acquire);
+    if (flags & B_VALID) == 0 {
+        crate::ide::iderw(idx);
+    }
+
+    idx
+}
+
+// Mark dirty + write to disk.
+pub fn bwrite(idx: usize) {
+    let b = buf_mut(idx);
+    b.flags.fetch_or(B_DIRTY, Ordering::AcqRel);
+    crate::ide::iderw(idx);
+}
+
+// Release buffer. If refcnt hits 0, move to MRU head.
+pub fn brelse(idx: usize) {
+    unsafe {
+        let b = &mut BCACHE.buf[idx];
+        if b.refcnt == 0 {
+            panic!("brelse: refcnt underflow");
+        }
+
+        b.refcnt -= 1;
+        if b.refcnt == 0 {
+            remove_from_list(idx);
+            insert_at_head(idx);
+        }
+    }
+}

src/buf.rs

@@ -0,0 +1,39 @@
+use core::sync::atomic::AtomicU32;
+
+pub const BSIZE: usize = 512; // block size
+pub const NBUF: usize = 30;   // same as xv6 default; can tune later
+
+pub const B_VALID: u32 = 0x2; // buffer has been read from disk
+pub const B_DIRTY: u32 = 0x4; // buffer needs to be written to disk
+
+#[repr(C)]
+pub struct Buf {
+    pub flags: AtomicU32,
+    pub dev: u32,
+    pub blockno: u32,
+    pub refcnt: u32,
+
+    // LRU list (intrusive, by index)
+    pub prev: usize,
+    pub next: usize,
+
+    // disk queue (by index)
+    pub qnext: Option<usize>,
+
+    pub data: [u8; BSIZE],
+}
+
+impl Buf {
+    pub const fn new() -> Self {
+        Self {
+            flags: AtomicU32::new(0),
+            dev: 0,
+            blockno: 0,
+            refcnt: 0,
+            prev: 0,
+            next: 0,
+            qnext: None,
+            data: [0; BSIZE],
+        }
+    }
+}