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实验三·bdev原理和源码分析

时间：2022-11-26 19:04:02浏览次数：123  
标签：io SPDK lab3 spdk 源码 context 原理 bdev

任务

  • 配置bdev运行环境

  • 运行hello_bdev程序并分析源码

  • 通过bdev接口写入数据并读取

Bdev是在物理设备上的进一步抽象，物理层有NVM、 NVMeOF、CEPH RBD等，通过bdev向上提供统一接口，应用层可屏蔽底层细节，直接面向bdev读写数据。 SPDK bdev对ZNS SSD支持不完善，bug较多，调试需要花费大量时间，后续实验采用普通NVMe进行。

实验过程

运行并分析hello_bdev.c源码

新建虚拟盘并启动

新建虚拟盘

qemu-img create -f qcow2 nvme.qcow2 10G

启动虚拟机

sudo qemu-system-x86_64 -name qemucsd -m 2G --enable-kvm -cpu host -smp 4 -hda ./ubuntu.qcow2 -net user,hostfwd=tcp:127.0.0.1:7777-:22,hostfwd=tcp:127.0.0.1:2222-:2000 -net nic -drive file=nvme.qcow2,if=none,id=nvm -device nvme,serial=deadbeef,drive=nvm -nographic -fsdev local,id=fsdev0,path=./work/,security_model=none  -device virtio-9p-pci,id=fs0,fsdev=fsdev0,mount_tag=hostshare

挂载共享目录

sudo mount hostshare -t 9p ./work

报错bad option; for several filesystems (e.g. nfs***, cifs) you might need a /sbin/mount. helper program.***

可能是因为启动时没有加参数-fsdev local,id=fsdev0,path=./work/,security_model=none -device virtio-9p-pci,id=fs0,fsdev=fsdev0,mount_tag=hostshare

初始化环境

sudo HUGEMEM=1024 scripts/setup.sh

生成配置文件

./scripts/gen_nvme.sh --json-with-subsystems > ./build/examples/nvme.json

运行hello_bdev程序

cd build/examples/
sudo ./hello_bdev -c nvme.json -b Nvme0n1

img

分析hello_bdev.c源码

文件目录：spdk/examples/bdev/hello_world/hello_bdev.c

主函数 main

暂时无法在飞书文档外展示此内容

函数hello_start

暂时无法在飞书文档外展示此内容

函数hello_write

暂时无法在飞书文档外展示此内容

函数write_complete

本函数中首先释放io，然后清空缓冲区，再调用hello_read函数。

函数hello_read

和hello_write类似，只是调用了读取相关的函数，读取成功后调用read_complete

函数read_complete

打印出读出的内容并且释放io和缓冲区、关闭服务等。

修改hello_bdev.c源码

要求：生成256KB字符串数据，修改hello_bdev.c源码将字符串数据通过bdev写入，之后再读取，验证结果是否正确

这部分参考了https://miracle24.site/other/cs-exp-zns-3/

/*   SPDX-License-Identifier: BSD-3-Clause
 *   Copyright (C) 2018 Intel Corporation.
 *   All rights reserved.
 */

#include "spdk/stdinc.h"
#include "spdk/thread.h"
#include "spdk/bdev.h"
#include "spdk/env.h"
#include "spdk/event.h"
#include "spdk/log.h"
#include "spdk/string.h"
#include "spdk/bdev_zone.h"

//生成随机数
#include "time.h"
#include "stdlib.h"

static char *g_bdev_name = "Nvme0n1";
const int STRING_LEN = 256*1024*8 // 随机生成字符串的长度为256KB

struct lab3_context_t {
    struct spdk_bdev *bdev;
    struct spdk_bdev_desc *bdev_desc;
    struct spdk_io_channel *bdev_io_channel;
    char *buff;
    uint32_t buff_size;
    char *bdev_name;
    struct spdk_bdev_io_wait_entry bdev_io_wait;
};

/*
 * 生成随机256KB数据
 */

static char* random_str(void)
{
    //开辟字符串空间并清零
    char *str = (char*)malloc(STRING_LEN);
    memset(str, 0 , STRING_LEN);
    if(str)
    {
        //生成随机种子
        srand((unsigned int)time(0));
        //在字符串每一位填入随机可显示的ASCII码
        int i = 0;
        for(i=0;i<STRING_LEN;i++)
        {
            str[i] = (char) (32 + rand() % 93);
        }
        return str;
    }
    else
    {
        printf("字符串开辟失败\n");
            SPDK_ERRLOG("Failed to allocate buffer\n");
            spdk_put_io_channel(lab3_context->bdev_io_channel);
            spdk_bdev_close(lab3_context->bdev_desc);
            spdk_app_stop(-1);
            return NULL;
    }
}

/*
 * Usage function for printing parameters that are specific to this application
 */
static void
lab3_bdev_usage(void)
{
    printf(" -b <bdev>                 name of the bdev to use\n");
}

/*
 * This function is called to parse the parameters that are specific to this application
 */
static int
lab3_bdev_parse_arg(int ch, char *arg)
{
    switch (ch) {
    case 'b':
        g_bdev_name = arg;
        break;
    default:
        return -EINVAL;
    }
    return 0;
}

/*
 * Callback function for read io completion.
 */
static void
read_complete(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
{
    struct lab3_context_t *lab3_context = cb_arg;

    if (success) {
        SPDK_NOTICELOG("Read string from bdev : %s\n", lab3_context->buff);
    } else {
        SPDK_ERRLOG("bdev io read error\n");
    }

    /* Complete the bdev io and close the channel */
    spdk_bdev_free_io(bdev_io);
    spdk_put_io_channel(lab3_context->bdev_io_channel);
    spdk_bdev_close(lab3_context->bdev_desc);
    SPDK_NOTICELOG("Stopping app\n");
    spdk_app_stop(success ? 0 : -1);
}

static void
lab3_read(void *arg)
{
    struct lab3_context_t *lab3_context = arg;
    int rc = 0;

    SPDK_NOTICELOG("Reading io\n");
    rc = spdk_bdev_read(lab3_context->bdev_desc, lab3_context->bdev_io_channel,
                lab3_context->buff, 0, lab3_context->buff_size, read_complete,
                lab3_context);

    if (rc == -ENOMEM) {
        SPDK_NOTICELOG("Queueing io\n");
        /* In case we cannot perform I/O now, queue I/O */
        lab3_context->bdev_io_wait.bdev = lab3_context->bdev;
        lab3_context->bdev_io_wait.cb_fn = lab3_read;
        lab3_context->bdev_io_wait.cb_arg = lab3_context;
        spdk_bdev_queue_io_wait(lab3_context->bdev, lab3_context->bdev_io_channel,
                    &lab3_context->bdev_io_wait);
    } else if (rc) {
        SPDK_ERRLOG("%s error while reading from bdev: %d\n", spdk_strerror(-rc), rc);
        spdk_put_io_channel(lab3_context->bdev_io_channel);
        spdk_bdev_close(lab3_context->bdev_desc);
        spdk_app_stop(-1);
    }
}

/*
 * Callback function for write io completion.
 */
static void
write_complete(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
{
    struct lab3_context_t *lab3_context = cb_arg;

    /* Complete the I/O */
    spdk_bdev_free_io(bdev_io);

    if (success) {
        SPDK_NOTICELOG("bdev io write completed successfully\n");
    } else {
        SPDK_ERRLOG("bdev io write error: %d\n", EIO);
        spdk_put_io_channel(lab3_context->bdev_io_channel);
        spdk_bdev_close(lab3_context->bdev_desc);
        spdk_app_stop(-1);
        return;
    }

    /* Zero the buffer so that we can use it for reading */
    memset(lab3_context->buff, 0, lab3_context->buff_size);

    lab3_read(lab3_context);
}

static void
lab3_write(void *arg)
{
    struct lab3_context_t *lab3_context = arg;
    int rc = 0;

    SPDK_NOTICELOG("Writing to the bdev\n");
    rc = spdk_bdev_write(lab3_context->bdev_desc, lab3_context->bdev_io_channel,
                 lab3_context->buff, 0, lab3_context->buff_size, write_complete,
                 lab3_context);

    if (rc == -ENOMEM) {
        SPDK_NOTICELOG("Queueing io\n");
        lab3_context->bdev_io_wait.bdev = lab3_context->bdev;
        lab3_context->bdev_io_wait.cb_fn = lab3_write;
        lab3_context->bdev_io_wait.cb_arg = lab3_context;
        spdk_bdev_queue_io_wait(lab3_context->bdev, lab3_context->bdev_io_channel,
                    &lab3_context->bdev_io_wait);
    } else if (rc) {
        SPDK_ERRLOG("%s error while writing to bdev: %d\n", spdk_strerror(-rc), rc);
        spdk_put_io_channel(lab3_context->bdev_io_channel);
        spdk_bdev_close(lab3_context->bdev_desc);
        spdk_app_stop(-1);
    }
}

static void
lab3_bdev_event_cb(enum spdk_bdev_event_type type, struct spdk_bdev *bdev,
            void *event_ctx)
{
    SPDK_NOTICELOG("Unsupported bdev event: type %d\n", type);
}

static void
reset_zone_complete(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
{
    struct lab3_context_t *lab3_context = cb_arg;

    /* Complete the I/O */
    spdk_bdev_free_io(bdev_io);

    if (!success) {
        SPDK_ERRLOG("bdev io reset zone error: %d\n", EIO);
        spdk_put_io_channel(lab3_context->bdev_io_channel);
        spdk_bdev_close(lab3_context->bdev_desc);
        spdk_app_stop(-1);
        return;
    }

    lab3_write(lab3_context);
}

static void
lab3_reset_zone(void *arg)
{
    struct lab3_context_t *lab3_context = arg;
    int rc = 0;

    rc = spdk_bdev_zone_management(lab3_context->bdev_desc, lab3_context->bdev_io_channel,
                       0, SPDK_BDEV_ZONE_RESET, reset_zone_complete, lab3_context);

    if (rc == -ENOMEM) {
        SPDK_NOTICELOG("Queueing io\n");
        /* In case we cannot perform I/O now, queue I/O */
        lab3_context->bdev_io_wait.bdev = lab3_context->bdev;
        lab3_context->bdev_io_wait.cb_fn = lab3_reset_zone;
        lab3_context->bdev_io_wait.cb_arg = lab3_context;
        spdk_bdev_queue_io_wait(lab3_context->bdev, lab3_context->bdev_io_channel,
                    &lab3_context->bdev_io_wait);
    } else if (rc) {
        SPDK_ERRLOG("%s error while resetting zone: %d\n", spdk_strerror(-rc), rc);
        spdk_put_io_channel(lab3_context->bdev_io_channel);
        spdk_bdev_close(lab3_context->bdev_desc);
        spdk_app_stop(-1);
    }
}

static void
lab3_start(void *arg1)
{
    struct lab3_context_t *lab3_context = arg1;
    uint32_t buf_align;
    int rc = 0;
    lab3_context->bdev = NULL;
    lab3_context->bdev_desc = NULL;

    SPDK_NOTICELOG("Successfully started the application\n");

    SPDK_NOTICELOG("Opening the bdev %s\n", lab3_context->bdev_name);
    rc = spdk_bdev_open_ext(lab3_context->bdev_name, true, lab3_bdev_event_cb, NULL,
                &lab3_context->bdev_desc);
    if (rc) {
        SPDK_ERRLOG("Could not open bdev: %s\n", lab3_context->bdev_name);
        spdk_app_stop(-1);
        return;
    }

    lab3_context->bdev = spdk_bdev_desc_get_bdev(lab3_context->bdev_desc);

    SPDK_NOTICELOG("Opening io channel\n");

    lab3_context->bdev_io_channel = spdk_bdev_get_io_channel(lab3_context->bdev_desc);
    if (lab3_context->bdev_io_channel == NULL) {
        SPDK_ERRLOG("Could not create bdev I/O channel!!\n");
        spdk_bdev_close(lab3_context->bdev_desc);
        spdk_app_stop(-1);
        return;
    }

    lab3_context->buff_size = spdk_bdev_get_block_size(lab3_context->bdev) *
                //    spdk_bdev_get_write_unit_size(lab3_context->bdev);
                ceil((STRING_LEN/8.0)/spdk_bdev_get_block_size(lab3_context->bdev));
    buf_align = spdk_bdev_get_buf_align(lab3_context->bdev);
    lab3_context->buff = spdk_dma_zmalloc(lab3_context->buff_size, buf_align, NULL);
    if (!lab3_context->buff) {
        SPDK_ERRLOG("Failed to allocate buffer\n");
        spdk_put_io_channel(lab3_context->bdev_io_channel);
        spdk_bdev_close(lab3_context->bdev_desc);
        spdk_app_stop(-1);
        return;
    }
    sprintf(lab3_context->buff,, "%s", random_str());

    if (spdk_bdev_is_zoned(lab3_context->bdev)) {
        lab3_reset_zone(lab3_context);
        /* If bdev is zoned, the callback, reset_zone_complete, will call lab3_write() */
        return;
    }

    lab3_write(lab3_context);
}

int
main(int argc, char **argv)
{
    struct spdk_app_opts opts = {};
    int rc = 0;
    struct lab3_context_t lab3_context = {};

    
    spdk_app_opts_init(&opts, sizeof(opts));
    opts.name = "lab3_bdev";

    /*
     * Parse built-in SPDK command line parameters as well
     * as our custom one(s).
     */
    if ((rc = spdk_app_parse_args(argc, argv, &opts, "b:", NULL, lab3_bdev_parse_arg,
                      lab3_bdev_usage)) != SPDK_APP_PARSE_ARGS_SUCCESS) {
        exit(rc);
    }
    lab3_context.bdev_name = g_bdev_name;

    /*
     * spdk_app_start() will initialize the SPDK framework, call lab3_start(),
     * and then block until spdk_app_stop() is called (or if an initialization
     * error occurs, spdk_app_start() will return with rc even without calling
     * lab3_start().
     */
    rc = spdk_app_start(&opts, lab3_start, &lab3_context);
    if (rc) {
        SPDK_ERRLOG("ERROR starting application\n");
    }

    /* At this point either spdk_app_stop() was called, or spdk_app_start()
     * failed because of internal error.
     */

    /* When the app stops, free up memory that we allocated. */
    spdk_dma_free(lab3_context.buff);

    /* Gracefully close out all of the SPDK subsystems. */
    spdk_app_fini();
    return rc;
}
SPDK_ROOT_DIR := /home/cwj/work/spdk

include $(SPDK_ROOT_DIR)/mk/spdk.common.mk
include $(SPDK_ROOT_DIR)/mk/spdk.modules.mk

APP = lab3_code

C_SRCS := lab3_code.c

SPDK_LIB_LIST = $(ALL_MODULES_LIST) event event_bdev

include $(SPDK_ROOT_DIR)/mk/spdk.app.mk

run: all
    @ echo "编译结束，清除中间文件"
    @ rm -f lab3_code.d lab3_code.o
    @ echo "生成配置文件"
    @ $(SPDK_ROOT_DIR)/scripts/gen_nvme.sh --json-with-subsystems > ./lab3_code.json
    @ echo "运行程序"
    @ sudo ./lab3_code -c ./lab3_code.json
    @ echo "数据大小：按照要求是256KB"
    @ echo " "
    @ du -h data.*
    @ echo " "
    @ echo "比较数据内容，没有输出则是相同"
    @ diff data.in data.out

运行修改后的程序

sudo HUGEMEM=1024 scripts/setup.sh
cd ..
cd lab3
make run

img

可见完成了实验要求。

标签：io,SPDK,lab3,spdk,源码,context,原理,bdev
From： https://www.cnblogs.com/hushrush/p/16928031.html

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