--- /dev/null
+/*
+ * device DAX engine
+ *
+ * IO engine that reads/writes from files by doing memcpy to/from
+ * a memory mapped region of DAX enabled device.
+ *
+ * Copyright (C) 2016 Intel Corp
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License,
+ * version 2 as published by the Free Software Foundation..
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+/*
+ * device dax engine
+ * IO engine that access a DAX device directly for read and write data
+ *
+ * To use:
+ * ioengine=dev-dax
+ *
+ * Other relevant settings:
+ * iodepth=1
+ * direct=0 REQUIRED
+ * filename=/dev/daxN.N
+ * bs=2m
+ *
+ * direct should be left to 0. Using dev-dax implies that memory access
+ * is direct. However, dev-dax does not support O_DIRECT flag by design
+ * since it is not necessary.
+ *
+ * bs should adhere to the device dax alignment at minimally.
+ *
+ * libpmem.so
+ * By default, the dev-dax engine will let the system find the libpmem.so
+ * that it uses. You can use an alternative libpmem by setting the
+ * FIO_PMEM_LIB environment variable to the full path to the desired
+ * libpmem.so.
+ */
+
+#include <stdio.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <dlfcn.h>
+#include <libgen.h>
+
+#include "../fio.h"
+#include "../verify.h"
+
+/*
+ * Limits us to 1GB of mapped files in total to model after
+ * mmap engine behavior
+ */
+#define MMAP_TOTAL_SZ (1 * 1024 * 1024 * 1024UL)
+
+struct fio_devdax_data {
+ void *devdax_ptr;
+ size_t devdax_sz;
+ off_t devdax_off;
+};
+
+static void * (*pmem_memcpy_persist)(void *dest, const void *src, size_t len);
+
+static int fio_devdax_file(struct thread_data *td, struct fio_file *f,
+ size_t length, off_t off)
+{
+ struct fio_devdax_data *fdd = FILE_ENG_DATA(f);
+ int flags = 0;
+
+ if (td_rw(td))
+ flags = PROT_READ | PROT_WRITE;
+ else if (td_write(td)) {
+ flags = PROT_WRITE;
+
+ if (td->o.verify != VERIFY_NONE)
+ flags |= PROT_READ;
+ } else
+ flags = PROT_READ;
+
+ fdd->devdax_ptr = mmap(NULL, length, flags, MAP_SHARED, f->fd, off);
+ if (fdd->devdax_ptr == MAP_FAILED) {
+ fdd->devdax_ptr = NULL;
+ td_verror(td, errno, "mmap");
+ }
+
+ if (td->error && fdd->devdax_ptr)
+ munmap(fdd->devdax_ptr, length);
+
+ return td->error;
+}
+
+/*
+ * Just mmap an appropriate portion, we cannot mmap the full extent
+ */
+static int fio_devdax_prep_limited(struct thread_data *td, struct io_u *io_u)
+{
+ struct fio_file *f = io_u->file;
+ struct fio_devdax_data *fdd = FILE_ENG_DATA(f);
+
+ if (io_u->buflen > f->real_file_size) {
+ log_err("fio: bs too big for dev-dax engine\n");
+ return EIO;
+ }
+
+ fdd->devdax_sz = min(MMAP_TOTAL_SZ, f->real_file_size);
+ if (fdd->devdax_sz > f->io_size)
+ fdd->devdax_sz = f->io_size;
+
+ fdd->devdax_off = io_u->offset;
+
+ return fio_devdax_file(td, f, fdd->devdax_sz, fdd->devdax_off);
+}
+
+/*
+ * Attempt to mmap the entire file
+ */
+static int fio_devdax_prep_full(struct thread_data *td, struct io_u *io_u)
+{
+ struct fio_file *f = io_u->file;
+ struct fio_devdax_data *fdd = FILE_ENG_DATA(f);
+ int ret;
+
+ if (fio_file_partial_mmap(f))
+ return EINVAL;
+
+ if (io_u->offset != (size_t) io_u->offset ||
+ f->io_size != (size_t) f->io_size) {
+ fio_file_set_partial_mmap(f);
+ return EINVAL;
+ }
+
+ fdd->devdax_sz = f->io_size;
+ fdd->devdax_off = 0;
+
+ ret = fio_devdax_file(td, f, fdd->devdax_sz, fdd->devdax_off);
+ if (ret)
+ fio_file_set_partial_mmap(f);
+
+ return ret;
+}
+
+static int fio_devdax_prep(struct thread_data *td, struct io_u *io_u)
+{
+ struct fio_file *f = io_u->file;
+ struct fio_devdax_data *fdd = FILE_ENG_DATA(f);
+ int ret;
+
+ /*
+ * It fits within existing mapping, use it
+ */
+ if (io_u->offset >= fdd->devdax_off &&
+ io_u->offset + io_u->buflen < fdd->devdax_off + fdd->devdax_sz)
+ goto done;
+
+ /*
+ * unmap any existing mapping
+ */
+ if (fdd->devdax_ptr) {
+ if (munmap(fdd->devdax_ptr, fdd->devdax_sz) < 0)
+ return errno;
+ fdd->devdax_ptr = NULL;
+ }
+
+ if (fio_devdax_prep_full(td, io_u)) {
+ td_clear_error(td);
+ ret = fio_devdax_prep_limited(td, io_u);
+ if (ret)
+ return ret;
+ }
+
+done:
+ io_u->mmap_data = fdd->devdax_ptr + io_u->offset - fdd->devdax_off -
+ f->file_offset;
+ return 0;
+}
+
+static int fio_devdax_queue(struct thread_data *td, struct io_u *io_u)
+{
+ fio_ro_check(td, io_u);
+ io_u->error = 0;
+
+ switch (io_u->ddir) {
+ case DDIR_READ:
+ memcpy(io_u->xfer_buf, io_u->mmap_data, io_u->xfer_buflen);
+ break;
+ case DDIR_WRITE:
+ pmem_memcpy_persist(io_u->mmap_data, io_u->xfer_buf,
+ io_u->xfer_buflen);
+ break;
+ case DDIR_SYNC:
+ case DDIR_DATASYNC:
+ case DDIR_SYNC_FILE_RANGE:
+ break;
+ default:
+ io_u->error = EINVAL;
+ break;
+ }
+
+ return FIO_Q_COMPLETED;
+}
+
+static int fio_devdax_init(struct thread_data *td)
+{
+ struct thread_options *o = &td->o;
+ const char *path;
+ void *dl;
+
+ if ((o->rw_min_bs & page_mask) &&
+ (o->fsync_blocks || o->fdatasync_blocks)) {
+ log_err("fio: mmap options dictate a minimum block size of "
+ "%llu bytes\n", (unsigned long long) page_size);
+ return 1;
+ }
+
+ path = getenv("FIO_PMEM_LIB");
+ if (!path)
+ path = "libpmem.so";
+
+ dl = dlopen(path, RTLD_NOW | RTLD_NODELETE);
+ if (!dl) {
+ log_err("fio: unable to open libpmem: %s\n", dlerror());
+ return 1;
+ }
+
+ pmem_memcpy_persist = dlsym(dl, "pmem_memcpy_persist");
+ if (!pmem_memcpy_persist) {
+ log_err("fio: unable to load libpmem: %s\n", dlerror());
+ return 1;
+ }
+
+ return 0;
+}
+
+static int fio_devdax_open_file(struct thread_data *td, struct fio_file *f)
+{
+ struct fio_devdax_data *fdd;
+ int ret;
+
+ ret = generic_open_file(td, f);
+ if (ret)
+ return ret;
+
+ fdd = calloc(1, sizeof(*fdd));
+ if (!fdd) {
+ int fio_unused __ret;
+ __ret = generic_close_file(td, f);
+ return 1;
+ }
+
+ FILE_SET_ENG_DATA(f, fdd);
+
+ return 0;
+}
+
+static int fio_devdax_close_file(struct thread_data *td, struct fio_file *f)
+{
+ struct fio_devdax_data *fdd = FILE_ENG_DATA(f);
+
+ FILE_SET_ENG_DATA(f, NULL);
+ free(fdd);
+ fio_file_clear_partial_mmap(f);
+
+ return generic_close_file(td, f);
+}
+
+static int
+fio_devdax_get_file_size(struct thread_data *td, struct fio_file *f)
+{
+ char spath[PATH_MAX];
+ char npath[PATH_MAX];
+ char *rpath;
+ FILE *sfile;
+ uint64_t size;
+ struct stat st;
+ int rc;
+
+ if (fio_file_size_known(f))
+ return 0;
+
+ if (f->filetype != FIO_TYPE_CHAR)
+ return -EINVAL;
+
+ rc = stat(f->file_name, &st);
+ if (rc < 0) {
+ log_err("%s: failed to stat file %s: %d\n",
+ td->o.name, f->file_name, errno);
+ return -errno;
+ }
+
+ snprintf(spath, PATH_MAX, "/sys/dev/char/%d:%d/subsystem",
+ major(st.st_rdev), minor(st.st_rdev));
+
+ rpath = realpath(spath, npath);
+ if (!rpath) {
+ log_err("%s: realpath on %s failed: %d\n",
+ td->o.name, spath, errno);
+ return -errno;
+ }
+
+ /* check if DAX device */
+ if (strcmp("/sys/class/dax", rpath)) {
+ log_err("%s: %s not a DAX device!\n",
+ td->o.name, f->file_name);
+ }
+
+ snprintf(spath, PATH_MAX, "/sys/dev/char/%d:%d/size",
+ major(st.st_rdev), minor(st.st_rdev));
+
+ sfile = fopen(spath, "r");
+ if (!sfile) {
+ log_err("%s: fopen on %s failed: %d\n",
+ td->o.name, spath, errno);
+ return 1;
+ }
+
+ rc = fscanf(sfile, "%lu", &size);
+ if (rc < 0) {
+ log_err("%s: fscanf on %s failed: %d\n",
+ td->o.name, spath, errno);
+ return 1;
+ }
+
+ f->real_file_size = size;
+
+ fclose(sfile);
+
+ if (f->file_offset > f->real_file_size) {
+ log_err("%s: offset extends end (%llu > %llu)\n", td->o.name,
+ (unsigned long long) f->file_offset,
+ (unsigned long long) f->real_file_size);
+ return 1;
+ }
+
+ fio_file_set_size_known(f);
+ return 0;
+}
+
+static struct ioengine_ops ioengine = {
+ .name = "dev-dax",
+ .version = FIO_IOOPS_VERSION,
+ .init = fio_devdax_init,
+ .prep = fio_devdax_prep,
+ .queue = fio_devdax_queue,
+ .open_file = fio_devdax_open_file,
+ .close_file = fio_devdax_close_file,
+ .get_file_size = fio_devdax_get_file_size,
+ .flags = FIO_SYNCIO | FIO_DISKLESSIO | FIO_NOEXTEND | FIO_NODISKUTIL,
+};
+
+static void fio_init fio_devdax_register(void)
+{
+ register_ioengine(&ioengine);
+}
+
+static void fio_exit fio_devdax_unregister(void)
+{
+ unregister_ioengine(&ioengine);
+}
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