网站建设的基本过程,主机托管网站,企业微信公众号开发,静态网站后台内核版本#xff1a;4.14.0 基于设备树 使用请求队列#xff0c;请求队列会用到I/O调度器#xff0c;适合机械硬盘这种存储设备。
#include linux/module.h
#include linux/blkdev.h
#include linux/hdreg.h #define RAMDISK_SIZE (2*1024*1024… 内核版本4.14.0 基于设备树 使用请求队列请求队列会用到I/O调度器适合机械硬盘这种存储设备。
#include linux/module.h
#include linux/blkdev.h
#include linux/hdreg.h #define RAMDISK_SIZE (2*1024*1024) /* capacity size is 2MB */
#define RAMDISK_NAME ramdisk
#define RAMDISK_MINORS 3 /* The number of disk partitions *//* ramdisk device struct */
struct ramdisk_info{int major; /* major device id */unsigned char *ramdisk_buf; /* ramdisk memory space */spinlock_t spinlock;struct gendisk *gendisk;struct request_queue *queue;
};static struct ramdisk_info ramdisk;/* * description : handling the transfer * param-req : request * return : none */
static void ramdisk_transfer(struct request *req)
{void *buffer;/* * Gets the byte address and size of the write or read disk.* blk_rq_pos gets the sector address, which is converted to a byte address by a left shift of 9 bits.* blk_rq_cur_bytes gets the size. */ unsigned long start blk_rq_pos(req)9;unsigned long len blk_rq_cur_bytes(req);/* the data buffer in the bio */buffer bio_data(req-bio);if (READ rq_data_dir(req))memcpy(buffer, ramdisk.ramdisk_bufstart, len);elsememcpy(ramdisk.ramdisk_bufstart, buffer, len);
}/* * description : request handler function * param-q : request queue * return : none*/
static void ramdisk_request_fn(struct request_queue *queue)
{struct request *req;blk_status_t err BLK_STS_OK;/* loop processes each request in the request queue */req blk_fetch_request(queue);while (req ! NULL){/* specific transfer processing for the request */ramdisk_transfer(req);if (!__blk_end_request_cur(req, err))req blk_fetch_request(queue);}
}/* * description : open the block device * param - dev : block device * param - mode : the open mode * return : 0 means success, others means failure */
static int ramdisk_open(struct block_device *dev, fmode_t mode)
{ printk(KERN_INFO ramdisk opened\n); return 0;
}/** description : release the block device * param - disk : gendisk * param - mode : mode * return : 0 means success, others means failure*/
static void ramdisk_release(struct gendisk *disk, fmode_t mode)
{ printk(ramdisk released\n);
} /* * description : get information of gendisk * param - dev : block device * param - geo : mode * return : 0 means success, others means failure*/
static int ramdisk_getgeo(struct block_device *dev, struct hd_geometry *geo)
{ /* 这是相对于机械硬盘的概念 */ geo-heads 2; //磁头geo-cylinders 32; //柱面 geo-sectors RAMDISK_SIZE / (2 * 32 *512); // 磁道上的扇区数量 return 0;
} static struct block_device_operations ramdisk_fops { .owner THIS_MODULE, .open ramdisk_open, .release ramdisk_release, .getgeo ramdisk_getgeo,
}; static int __init ramdisk_init(void)
{int ret;/* Allocate memory for the ramdisk */ramdisk.ramdisk_buf kzalloc(RAMDISK_SIZE, GFP_KERNEL);if (NULL ramdisk.ramdisk_buf)return -ENOMEM;/* Initialize the spinlock */spin_lock_init(ramdisk.spinlock);/* register block device */ramdisk.major register_blkdev(0, RAMDISK_NAME);if (ramdisk.major 0){ret ramdisk.major;goto out1;}printk(KERN_INFO ramdisk major %d\n, ramdisk.major);/* Allocate and initialize the gendisk */ramdisk.gendisk alloc_disk(RAMDISK_MINORS);if (!ramdisk.gendisk){ret -ENOMEM;goto out2;}/* Allocate and initialize the request queue */ramdisk.queue blk_init_queue(ramdisk_request_fn, ramdisk.spinlock);if (!ramdisk.queue){ret -ENOMEM;goto out3;}/* Adding (registering) the disk */ramdisk.gendisk-major ramdisk.major; /* major device id */ramdisk.gendisk-first_minor 0; /* first minor device id */ramdisk.gendisk-fops ramdisk_fops; /* operation function */ramdisk.gendisk-private_data ramdisk; ramdisk.gendisk-queue ramdisk.queue;strcpy(ramdisk.gendisk-disk_name, RAMDISK_NAME);set_capacity(ramdisk.gendisk, RAMDISK_SIZE / 512); /* device capacity (in sectors(512M)) */add_disk(ramdisk.gendisk);return 0; out3:put_disk(ramdisk.gendisk);out2:unregister_blkdev(ramdisk.major, RAMDISK_NAME);out1:kfree(ramdisk.ramdisk_buf);return ret;
}static void __exit ramdisk_exit(void)
{/* uninstall gendisk */del_gendisk(ramdisk.gendisk);/* clean up request queue */blk_cleanup_queue(ramdisk.queue);/* release gendisk */put_disk(ramdisk.gendisk);/* unregister block device */unregister_blkdev(ramdisk.major, RAMDISK_NAME);/* release memory */kfree(ramdisk.ramdisk_buf);
}module_init(ramdisk_init);
module_exit(ramdisk_exit); /* * Author, driver information and LICENSE.*/
MODULE_AUTHOR(蒋楼丶);
MODULE_DESCRIPTION(RAMDISK_NAME Driver);
MODULE_LICENSE(GPL);对于EMMC、SD、ramdisk这样没有机械结构的存储设备我们可以直接访问任意一个扇区因此可以不需要I/O调度器也就不需要请求队列了。
#include linux/module.h
#include linux/blkdev.h
#include linux/hdreg.h #define RAMDISK_SIZE (2*1024*1024) /* capacity size is 2MB */
#define RAMDISK_NAME ramdisk
#define RAMDISK_MINORS 3 /* The number of disk partitions *//* ramdisk device struct */
struct ramdisk_info{int major; /* major device id */unsigned char *ramdisk_buf; /* ramdisk memory space */struct gendisk *gendisk;struct request_queue *queue;
};static struct ramdisk_info ramdisk;/* * description : make request function* param-queue : request queue* return : none */
static blk_qc_t ramdisk_make_request_fn(struct request_queue *queue, struct bio *bio)
{int offset;struct bio_vec bvec;struct bvec_iter iter;char *ptr;unsigned long len;/* get offset address of device */offset bio-bi_iter.bi_sector9;/* loop process each segment in the bio */bio_for_each_segment(bvec, bio, iter){ptr page_address(bvec.bv_page)bvec.bv_offset;len bvec.bv_len;if (bio_data_dir(bio) READ)memcpy(ptr, ramdisk.ramdisk_bufoffset, len);elsememcpy(ramdisk.ramdisk_bufoffset, ptr, len);offset len;}bio_endio(bio);return BLK_QC_T_NONE;
}/* * description : open the block device * param - dev : block device * param - mode : the open mode * return : 0 means success, others means failure */
static int ramdisk_open(struct block_device *dev, fmode_t mode)
{ printk(KERN_INFO ramdisk opened\n); return 0;
}/** description : release the block device * param - disk : gendisk * param - mode : mode * return : 0 means success, others means failure*/
static void ramdisk_release(struct gendisk *disk, fmode_t mode)
{ printk(ramdisk released\n);
} /* * description : get information of gendisk * param - dev : block device * param - geo : mode * return : 0 means success, others means failure*/
static int ramdisk_getgeo(struct block_device *dev, struct hd_geometry *geo)
{ /* 这是相对于机械硬盘的概念 */ geo-heads 2; //磁头geo-cylinders 32; //柱面 geo-sectors RAMDISK_SIZE / (2 * 32 *512); // 磁道上的扇区数量 return 0;
} static struct block_device_operations ramdisk_fops { .owner THIS_MODULE, .open ramdisk_open, .release ramdisk_release, .getgeo ramdisk_getgeo,
}; static int __init ramdisk_init(void)
{int ret;/* Allocate memory for the ramdisk */ramdisk.ramdisk_buf kzalloc(RAMDISK_SIZE, GFP_KERNEL);if (NULL ramdisk.ramdisk_buf)return -ENOMEM;/* register block device */ramdisk.major register_blkdev(0, RAMDISK_NAME);if (ramdisk.major 0){ret ramdisk.major;goto out1;}printk(KERN_INFO ramdisk major %d\n, ramdisk.major);/* Allocate and initialize the gendisk */ramdisk.gendisk alloc_disk(RAMDISK_MINORS);if (!ramdisk.gendisk){ret -ENOMEM;goto out2;}/* Allocate the request queue */ramdisk.queue blk_alloc_queue(GFP_KERNEL);if (!ramdisk.queue){ret -ENOMEM;goto out3;}/* set make request function */blk_queue_make_request(ramdisk.queue, ramdisk_make_request_fn);/* Adding (registering) the disk */ramdisk.gendisk-major ramdisk.major; /* major device id */ramdisk.gendisk-first_minor 0; /* first minor device id */ramdisk.gendisk-fops ramdisk_fops; /* operation function */ramdisk.gendisk-private_data ramdisk; ramdisk.gendisk-queue ramdisk.queue;strcpy(ramdisk.gendisk-disk_name, RAMDISK_NAME);set_capacity(ramdisk.gendisk, RAMDISK_SIZE / 512); /* device capacity (in sectors(512M)) */add_disk(ramdisk.gendisk);return 0; out3:put_disk(ramdisk.gendisk);out2:unregister_blkdev(ramdisk.major, RAMDISK_NAME);out1:kfree(ramdisk.ramdisk_buf);return ret;
}static void __exit ramdisk_exit(void)
{/* uninstall gendisk */del_gendisk(ramdisk.gendisk);/* clean up request queue */blk_cleanup_queue(ramdisk.queue);/* release gendisk */put_disk(ramdisk.gendisk);/* unregister block device */unregister_blkdev(ramdisk.major, RAMDISK_NAME);/* release memory */kfree(ramdisk.ramdisk_buf);
}module_init(ramdisk_init);
module_exit(ramdisk_exit); /* * Author, driver information and LICENSE.*/
MODULE_AUTHOR(蒋楼丶);
MODULE_DESCRIPTION(RAMDISK_NAME Driver);
MODULE_LICENSE(GPL);
