--- /dev/null
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/mman.h>
+
+// not correctly in the headers yet!!
+//#define O_DIRECT 0
+#ifndef O_DIRECT
+#define O_DIRECT 040000 /* direct disk access hint */
+#endif
+
+#define BLOCKSIZE 4096
+#define CERROR(fmt, arg...) fprintf(stderr, fmt, ## arg)
+#define __u64 long long
+#define LASSERT(v) do {} while(0)
+#define HTON__u64(v) (v)
+#define LPU64 "%Ld"
+#define LPX64 "%Lx"
+
+#define LPDS sizeof(__u64)
+int page_debug_setup(void *addr, int len, __u64 off, __u64 id)
+{
+ LASSERT(addr);
+
+ off = HTON__u64(off);
+ id = HTON__u64(id);
+ memcpy(addr, (char *)&off, LPDS);
+ memcpy(addr + LPDS, (char *)&id, LPDS);
+
+ addr += len - LPDS - LPDS;
+ memcpy(addr, (char *)&off, LPDS);
+ memcpy(addr + LPDS, (char *)&id, LPDS);
+
+ return 0;
+}
+
+int page_debug_check(char *who, void *addr, int end, __u64 off, __u64 id)
+{
+ __u64 ne_off;
+ int err = 0;
+
+ LASSERT(addr);
+
+ ne_off = HTON__u64(off);
+ id = HTON__u64(id);
+ if (memcmp(addr, (char *)&ne_off, LPDS)) {
+ CERROR("%s: for offset "LPU64" off: "LPX64" != "LPX64"\n",
+ who, off, *(__u64 *)addr, ne_off);
+ err = -EINVAL;
+ }
+ if (memcmp(addr + LPDS, (char *)&id, LPDS)) {
+ CERROR("%s: for offset "LPU64" id: "LPX64" != "LPX64"\n",
+ who, off, *(__u64 *)(addr + LPDS), id);
+ err = -EINVAL;
+ }
+
+ addr += end - LPDS - LPDS;
+ if (memcmp(addr, (char *)&ne_off, LPDS)) {
+ CERROR("%s: for offset "LPU64" end off: "LPX64" != "LPX64"\n",
+ who, off, *(__u64 *)addr, ne_off);
+ err = -EINVAL;
+ }
+ if (memcmp(addr + LPDS, (char *)&id, LPDS)) {
+ CERROR("%s: for offset "LPU64" end id: "LPX64" != "LPX64"\n",
+ who, off, *(__u64 *)(addr + LPDS), id);
+ err = -EINVAL;
+ }
+
+ return err;
+}
+#undef LPDS
+
+int main(int argc, char **argv)
+{
+ int fd;
+ char *buf;
+ long pg_vec, count;
+ long len;
+ long long end, offset;
+ long objid = 3;
+ int rc;
+
+ if (argc < 4 || argc > 5) {
+ fprintf(stderr,
+ "usage: %s file pages_per_vec count [objid]\n",
+ argv[0]);
+ return 1;
+ }
+
+ pg_vec = strtoul(argv[2], 0, 0);
+ count = strtoul(argv[3], 0, 0);
+ len = pg_vec * BLOCKSIZE;
+ end = (long long)count * len;
+ printf("directio on %s for %ldx%ld pages \n", argv[1], count, pg_vec);
+
+ buf = mmap(0, len, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, 0, 0);
+ if (!buf) {
+ fprintf(stderr, "No memory %s\n", strerror(errno));
+ return 2;
+ }
+
+ fd = open(argv[1], O_DIRECT | O_RDWR | O_CREAT);
+ if (fd == -1) {
+ fprintf(stderr, "Cannot open %s: %s\n", argv[1],
+ strerror(errno));
+ return 3;
+ }
+
+ for (offset = 0; offset < end; offset += len) {
+ int i;
+
+ for (i = 0; i < len; i += BLOCKSIZE)
+ page_debug_setup(buf + i, BLOCKSIZE, offset + i, objid);
+
+ rc = write(fd, buf, len);
+
+ for (i = 0; i < len; i += BLOCKSIZE) {
+ if (page_debug_check("write", buf + i, BLOCKSIZE,
+ offset + i, objid))
+ return 10;
+ }
+
+ if (rc != len) {
+ fprintf(stderr, "Write error: %s, rc %d\n",
+ strerror(errno), rc);
+ return 4;
+ }
+ }
+
+ if ( lseek(fd, 0, SEEK_SET) != 0 ) {
+ fprintf(stderr, "Cannot seek %s\n", strerror(errno));
+ return 5;
+ }
+
+ for (offset = 0; offset < end; offset += len) {
+ int i;
+
+ rc = read(fd, buf, len);
+ if (rc != len) {
+ fprintf(stderr, "Read error: %s, rc %d\n",
+ strerror(errno), rc);
+ return 6;
+ }
+
+ for (i = 0; i < len; i += BLOCKSIZE) {
+ if (page_debug_check("read", buf + i, BLOCKSIZE,
+ offset + i, objid))
+ return 11;
+ }
+ }
+
+ return 0;
+}