blkmtd.c

老版本的mtd-snap

		}
		numregions--;
		einfo++;
	}

	if(!numregions) {
		/* Not a valid erase block */
		err("erase: invalid erase request 0x%lX @ 0x%08zX", len, from);
		instr->state = MTD_ERASE_FAILED;
		err = -EIO;
	}

	if(instr->state != MTD_ERASE_FAILED) {
		/* do the erase */
		DEBUG(3, "Doing erase from = %zd len = %ld\n", from, len);
		err = write_pages(dev, NULL, from, len, &retlen);
		if(err || retlen != len) {
			err("erase failed err = %d", err);
			instr->state = MTD_ERASE_FAILED;
		} else {
			instr->state = MTD_ERASE_DONE;
		}
	}

	DEBUG(3, "blkmtd: erase: checking callback\n");
	mtd_erase_callback(instr);
	DEBUG(2, "blkmtd: erase: finished (err = %d)\n", err);
	return err;
}


/* read a range of the data via the page cache */
static int blkmtd_read(struct mtd_info *mtd, loff_t from, size_t len,
		       size_t *retlen, u_char *buf)
{
	struct blkmtd_dev *dev = mtd->priv;
	int err = 0;
	int offset;
	int pagenr, pages;
	size_t thislen = 0;

	DEBUG(2, "blkmtd: read: dev = `%s' from = %lld len = %zd buf = %p\n",
	      mtd->name+9, from, len, buf);

	if(from > mtd->size)
		return -EINVAL;
	if(from + len > mtd->size)
		len = mtd->size - from;

	pagenr = from >> PAGE_SHIFT;
	offset = from - (pagenr << PAGE_SHIFT);

	pages = (offset+len+PAGE_SIZE-1) >> PAGE_SHIFT;
	DEBUG(3, "blkmtd: read: pagenr = %d offset = %d, pages = %d\n",
	      pagenr, offset, pages);

	while(pages) {
		struct page *page;
		int cpylen;

		DEBUG(3, "blkmtd: read: looking for page: %d\n", pagenr);
		page = read_cache_page(dev->blkdev->bd_inode->i_mapping, pagenr, (filler_t *)blkmtd_readpage, dev);
		if(IS_ERR(page)) {
			err = -EIO;
			goto readerr;
		}

		cpylen = (PAGE_SIZE > len) ? len : PAGE_SIZE;
		if(offset+cpylen > PAGE_SIZE)
			cpylen = PAGE_SIZE-offset;

		memcpy(buf + thislen, page_address(page) + offset, cpylen);
		offset = 0;
		len -= cpylen;
		thislen += cpylen;
		pagenr++;
		pages--;
		if(!PageDirty(page))
			page_cache_release(page);
	}

 readerr:
	if(retlen)
		*retlen = thislen;
	DEBUG(2, "blkmtd: end read: retlen = %zd, err = %d\n", thislen, err);
	return err;
}


/* write data to the underlying device */
static int blkmtd_write(struct mtd_info *mtd, loff_t to, size_t len,
			size_t *retlen, const u_char *buf)
{
	struct blkmtd_dev *dev = mtd->priv;
	int err;

	if(!len)
		return 0;

	DEBUG(2, "blkmtd: write: dev = `%s' to = %lld len = %zd buf = %p\n",
	      mtd->name+9, to, len, buf);

	if(to >= mtd->size) {
		return -ENOSPC;
	}

	if(to + len > mtd->size) {
		len = mtd->size - to;
	}

	err = write_pages(dev, buf, to, len, retlen);
	if(err > 0)
		err = 0;
	DEBUG(2, "blkmtd: write: end, err = %d\n", err);
	return err;
}


/* sync the device - wait until the write queue is empty */
static void blkmtd_sync(struct mtd_info *mtd)
{
	/* Currently all writes are synchronous */
}


static void free_device(struct blkmtd_dev *dev)
{
	DEBUG(2, "blkmtd: free_device() dev = %p\n", dev);
	if(dev) {
		if(dev->mtd_info.eraseregions)
			kfree(dev->mtd_info.eraseregions);
		if(dev->mtd_info.name)
			kfree(dev->mtd_info.name);

		if(dev->blkdev) {
			invalidate_inode_pages(dev->blkdev->bd_inode->i_mapping);
			close_bdev_excl(dev->blkdev);
		}
		kfree(dev);
	}
}


/* For a given size and initial erase size, calculate the number
 * and size of each erase region. Goes round the loop twice,
 * once to find out how many regions, then allocates space,
 * then round the loop again to fill it in.
 */
static struct mtd_erase_region_info *calc_erase_regions(
	size_t erase_size, size_t total_size, int *regions)
{
	struct mtd_erase_region_info *info = NULL;

	DEBUG(2, "calc_erase_regions, es = %zd size = %zd regions = %d\n",
	      erase_size, total_size, *regions);
	/* Make any user specified erasesize be a power of 2
	   and at least PAGE_SIZE */
	if(erase_size) {
		int es = erase_size;
		erase_size = 1;
		while(es != 1) {
			es >>= 1;
			erase_size <<= 1;
		}
		if(erase_size < PAGE_SIZE)
			erase_size = PAGE_SIZE;
	} else {
		erase_size = CONFIG_MTD_BLKDEV_ERASESIZE;
	}

	*regions = 0;

	do {
		int tot_size = total_size;
		int er_size = erase_size;
		int count = 0, offset = 0, regcnt = 0;

		while(tot_size) {
			count = tot_size / er_size;
			if(count) {
				tot_size = tot_size % er_size;
				if(info) {
					DEBUG(2, "adding to erase info off=%d er=%d cnt=%d\n",
					      offset, er_size, count);
					(info+regcnt)->offset = offset;
					(info+regcnt)->erasesize = er_size;
					(info+regcnt)->numblocks = count;
					(*regions)++;
				}
				regcnt++;
				offset += (count * er_size);
			}
			while(er_size > tot_size)
				er_size >>= 1;
		}
		if(info == NULL) {
			info = kmalloc(regcnt * sizeof(struct mtd_erase_region_info), GFP_KERNEL);
			if(!info)
				break;
		}
	} while(!(*regions));
	DEBUG(2, "calc_erase_regions done, es = %zd size = %zd regions = %d\n",
	      erase_size, total_size, *regions);
	return info;
}


extern dev_t __init name_to_dev_t(const char *line);

static struct blkmtd_dev *add_device(char *devname, int readonly, int erase_size)
{
	struct block_device *bdev;
	int mode;
	struct blkmtd_dev *dev;

	if(!devname)
		return NULL;

	/* Get a handle on the device */


#ifdef MODULE
	mode = (readonly) ? O_RDONLY : O_RDWR;
	bdev = open_bdev_excl(devname, mode, NULL);
#else
	mode = (readonly) ? FMODE_READ : FMODE_WRITE;
	bdev = open_by_devnum(name_to_dev_t(devname), mode);
#endif
	if(IS_ERR(bdev)) {
		err("error: cannot open device %s", devname);
		DEBUG(2, "blkmtd: opening bdev returned %ld\n", PTR_ERR(bdev));
		return NULL;
	}

	DEBUG(1, "blkmtd: found a block device major = %d, minor = %d\n",
	      MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev));

	if(MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
		err("attempting to use an MTD device as a block device");
		blkdev_put(bdev);
		return NULL;
	}

	dev = kmalloc(sizeof(struct blkmtd_dev), GFP_KERNEL);
	if(dev == NULL) {
		blkdev_put(bdev);
		return NULL;
	}

	memset(dev, 0, sizeof(struct blkmtd_dev));
	dev->blkdev = bdev;
	if(!readonly) {
		init_MUTEX(&dev->wrbuf_mutex);
	}

	dev->mtd_info.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;

	/* Setup the MTD structure */
	/* make the name contain the block device in */
	dev->mtd_info.name = kmalloc(sizeof("blkmtd: ") + strlen(devname), GFP_KERNEL);
	if(dev->mtd_info.name == NULL)
		goto devinit_err;

	sprintf(dev->mtd_info.name, "blkmtd: %s", devname);
	dev->mtd_info.eraseregions = calc_erase_regions(erase_size, dev->mtd_info.size,
							&dev->mtd_info.numeraseregions);
	if(dev->mtd_info.eraseregions == NULL)
		goto devinit_err;

	dev->mtd_info.erasesize = dev->mtd_info.eraseregions->erasesize;
	DEBUG(1, "blkmtd: init: found %d erase regions\n",
	      dev->mtd_info.numeraseregions);

	if(readonly) {
		dev->mtd_info.type = MTD_ROM;
		dev->mtd_info.flags = MTD_CAP_ROM;
	} else {
		dev->mtd_info.type = MTD_RAM;
		dev->mtd_info.flags = MTD_CAP_RAM;
		dev->mtd_info.erase = blkmtd_erase;
		dev->mtd_info.write = blkmtd_write;
		dev->mtd_info.writev = default_mtd_writev;
		dev->mtd_info.sync = blkmtd_sync;
	}
	dev->mtd_info.read = blkmtd_read;
	dev->mtd_info.readv = default_mtd_readv;
	dev->mtd_info.priv = dev;
	dev->mtd_info.owner = THIS_MODULE;

	list_add(&dev->list, &blkmtd_device_list);
	if (add_mtd_device(&dev->mtd_info)) {
		/* Device didnt get added, so free the entry */
		list_del(&dev->list);
		goto devinit_err;
	} else {
		info("mtd%d: [%s] erase_size = %dKiB %s",
		     dev->mtd_info.index, dev->mtd_info.name + strlen("blkmtd: "),
		     dev->mtd_info.erasesize >> 10,
		     readonly ? "(read-only)" : "");
	}
	
	return dev;

 devinit_err:
	free_device(dev);
	return NULL;
}


/* Cleanup and exit - sync the device and kill of the kernel thread */
static void __devexit cleanup_blkmtd(void)
{
	struct list_head *temp1, *temp2;

	/* Remove the MTD devices */
	list_for_each_safe(temp1, temp2, &blkmtd_device_list) {
		struct blkmtd_dev *dev = list_entry(temp1, struct blkmtd_dev,
						    list);
		blkmtd_sync(&dev->mtd_info);
		del_mtd_device(&dev->mtd_info);
		info("mtd%d: [%s] removed", dev->mtd_info.index,
		     dev->mtd_info.name + strlen("blkmtd: "));
		list_del(&dev->list);
		free_device(dev);
	}
}

#ifndef MODULE

/* Handle kernel boot params */


static int __init param_blkmtd_device(char *str)
{
	int i;

	for(i = 0; i < MAX_DEVICES; i++) {
		device[i] = str;
		DEBUG(2, "blkmtd: device setup: %d = %s\n", i, device[i]);
		strsep(&str, ",");
	}
	return 1;
}


static int __init param_blkmtd_erasesz(char *str)
{
	int i;
	for(i = 0; i < MAX_DEVICES; i++) {
		char *val = strsep(&str, ",");
		if(val)
			erasesz[i] = simple_strtoul(val, NULL, 0);
		DEBUG(2, "blkmtd: erasesz setup: %d = %d\n", i, erasesz[i]);
	}

	return 1;
}


static int __init param_blkmtd_ro(char *str)
{
	int i;
	for(i = 0; i < MAX_DEVICES; i++) {
		char *val = strsep(&str, ",");
		if(val)
			ro[i] = simple_strtoul(val, NULL, 0);
		DEBUG(2, "blkmtd: ro setup: %d = %d\n", i, ro[i]);
	}

	return 1;
}


static int __init param_blkmtd_sync(char *str)
{
	if(str[0] == '1')
		sync = 1;
	return 1;
}

__setup("blkmtd_device=", param_blkmtd_device);
__setup("blkmtd_erasesz=", param_blkmtd_erasesz);
__setup("blkmtd_ro=", param_blkmtd_ro);
__setup("blkmtd_sync=", param_blkmtd_sync);

#endif


/* Startup */
static int __init init_blkmtd(void)
{
	int i;

	info("version " VERSION);
	/* Check args - device[0] is the bare minimum*/
	if(!device[0]) {
		err("error: missing `device' name\n");
		return -EINVAL;
	}

	for(i = 0; i < MAX_DEVICES; i++)
		add_device(device[i], ro[i], erasesz[i] << 10);

	if(list_empty(&blkmtd_device_list))
		return -EINVAL;

	return 0;
}

module_init(init_blkmtd);
module_exit(cleanup_blkmtd);