From 5db227b05ba316713d6793e728b21366e8337721 Mon Sep 17 00:00:00 2001
From: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Date: Sat, 4 Apr 2020 20:23:21 -0400
Subject: Initial commit

---
 .gitignore            |  1 +
 Makefile              | 22 ++++++++++++++++++++++
 nureadahead-collect   | 36 ++++++++++++++++++++++++++++++++++++
 nureadahead-init      | 30 ++++++++++++++++++++++++++++++
 nureadahead-preload.c | 38 ++++++++++++++++++++++++++++++++++++++
 5 files changed, 127 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100755 nureadahead-collect
 create mode 100755 nureadahead-init
 create mode 100644 nureadahead-preload.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..718456e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/nureadahead-preload
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..121272a
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,22 @@
+CFLAGS ?= -O2 -s
+CFLAGS += -Wall -Wextra
+
+prefix = /usr/local
+sbindir = $(prefix)/sbin
+
+all: nureadahead-preload
+
+nureadahead-preload: nureadahead-preload.c
+	$(CC) $(CFLAGS) $(LDFLAGS) $^ -o $@
+
+clean:
+	rm -f nureadahead-preload
+
+install: all
+	install -Dm755 nureadahead-collect $(DESTDIR)$(sbindir)
+	install -Dm755 nureadahead-collect-auto $(DESTDIR)$(sbindir)
+	install -Dm755 nureadahead-init $(DESTDIR)$(sbindir)
+	install -Dm755 nureadahead-merge $(DESTDIR)$(sbindir)
+	install -Dm755 nureadahead-preload $(DESTDIR)$(sbindir)
+
+.PHONY: all clean install
diff --git a/nureadahead-collect b/nureadahead-collect
new file mode 100755
index 0000000..9cf17fe
--- /dev/null
+++ b/nureadahead-collect
@@ -0,0 +1,36 @@
+#!/bin/sh
+
+usage() {
+    echo "usage: nureadahead-collect DEVICE TIMEOUT > file" >&2
+}
+
+case "$1" in
+    -*) usage; exit 1
+esac
+
+case "$#" in
+    2) device=$1 timeout=$2;;
+    *) usage; exit 1
+esac
+
+awk_prog2='
+$1 <= end && $2 > end {
+    end = $2
+}
+$1 > end && NR != 1 {
+    print start " " end
+}
+$1 > end {
+    start = $1
+    end = $2
+}
+END {
+    print start " " end
+}
+'
+
+blktrace -a read -d "$1" -w "$timeout" -o - \
+    | blkparse -f "%a %d %e %n %S\n" -i - \
+    | awk '$1 == "C" && $2 ~ /R/ && $2 !~ /A/ && $3 == 0 { print $5 " " $5 + $4 - 1 }' \
+    | sort -n -k1,1 -k2,2 \
+    | awk "$awk_prog2"
diff --git a/nureadahead-init b/nureadahead-init
new file mode 100755
index 0000000..f8b315b
--- /dev/null
+++ b/nureadahead-init
@@ -0,0 +1,30 @@
+#!/bin/sh
+
+usage() {
+    echo "usage: nureadahead-init [FILE [TIMEOUT [INIT [ARGS...]]]]" >&2
+}
+
+case "$1" in
+    -*) usage; exit 1
+esac
+
+case "$#" in
+    0) file=/.nureadahead            timeout=120 init=init;;
+    1) file=$1                       timeout=120 init=init; shift 1;;
+    2) file=$1                       timeout=$2  init=init; shift 2;;
+    *) file=$1                       timeout=$2  init=$3;   shift 3;;
+esac
+
+export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+device=$(awk '$2 == "/" { d=$1 } END { print d }' < /proc/self/mounts)
+if [ -n "$device" ]; then
+    if [ -e "$file" ]; then
+        nureadahead-preload "$device" < "$file" &
+    else
+        echo "nureadahead-init: no file, skipping preload" >&2
+    fi
+    nureadahead-collect "$device" "$timeout" > "$file" &
+else
+    echo "nureadahead-init: cannot find root device, skipping preload + collect" >&2
+fi
+exec "$init" "$@"
diff --git a/nureadahead-preload.c b/nureadahead-preload.c
new file mode 100644
index 0000000..7d10df8
--- /dev/null
+++ b/nureadahead-preload.c
@@ -0,0 +1,38 @@
+#define _POSIX_C_SOURCE 200112L
+#include <assert.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void usage() {
+    fputs("usage: nureadahead-preload DEVICE < file\n", stderr);
+}
+
+int main(int argc, char *argv[]) {
+    if (argc != 2 || argv[1][0] == '-' || argv[1][0] == '\0') {
+        usage();
+        exit(1);
+    }
+
+    int fd = open(argv[1], O_RDONLY);
+    if (fd == -1) {
+        perror("nureadahead-preload");
+        exit(1);
+    }
+
+    while (1) {
+        unsigned long long start, end;
+        switch (scanf("%llu %llu\n", &start, &end)) {
+            case 2:
+                if (posix_fadvise(fd, start * 512, (end - start + 1) * 512, POSIX_FADV_WILLNEED) == -1) {
+                    perror("nureadahead-preload: readahead");
+                    exit(1);
+                }
+                break;
+            case EOF:
+                exit(0);
+            default:
+                fputs("nureadahead-preload: invalid input\n", stderr);
+        }
+    }
+}
-- 
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