496 строки
11 KiB
C
496 строки
11 KiB
C
/*
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* $Id: block2mtd.c,v 1.23 2005/01/05 17:05:46 dwmw2 Exp $
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*
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* block2mtd.c - create an mtd from a block device
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*
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* Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk>
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* Copyright (C) 2004 Gareth Bult <Gareth@Encryptec.net>
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* Copyright (C) 2004,2005 Jörn Engel <joern@wh.fh-wedel.de>
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*
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* Licence: GPL
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/bio.h>
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#include <linux/pagemap.h>
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#include <linux/list.h>
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#include <linux/init.h>
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#include <linux/mtd/mtd.h>
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#include <linux/buffer_head.h>
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#define VERSION "$Revision: 1.23 $"
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#define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
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#define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
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/* Info for the block device */
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struct block2mtd_dev {
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struct list_head list;
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struct block_device *blkdev;
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struct mtd_info mtd;
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struct semaphore write_mutex;
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};
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/* Static info about the MTD, used in cleanup_module */
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static LIST_HEAD(blkmtd_device_list);
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#define PAGE_READAHEAD 64
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void cache_readahead(struct address_space *mapping, int index)
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{
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filler_t *filler = (filler_t*)mapping->a_ops->readpage;
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int i, pagei;
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unsigned ret = 0;
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unsigned long end_index;
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struct page *page;
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LIST_HEAD(page_pool);
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struct inode *inode = mapping->host;
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loff_t isize = i_size_read(inode);
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if (!isize) {
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INFO("iSize=0 in cache_readahead\n");
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return;
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}
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end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);
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read_lock_irq(&mapping->tree_lock);
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for (i = 0; i < PAGE_READAHEAD; i++) {
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pagei = index + i;
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if (pagei > end_index) {
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INFO("Overrun end of disk in cache readahead\n");
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break;
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}
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page = radix_tree_lookup(&mapping->page_tree, pagei);
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if (page && (!i))
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break;
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if (page)
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continue;
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read_unlock_irq(&mapping->tree_lock);
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page = page_cache_alloc_cold(mapping);
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read_lock_irq(&mapping->tree_lock);
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if (!page)
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break;
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page->index = pagei;
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list_add(&page->lru, &page_pool);
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ret++;
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}
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read_unlock_irq(&mapping->tree_lock);
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if (ret)
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read_cache_pages(mapping, &page_pool, filler, NULL);
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}
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static struct page* page_readahead(struct address_space *mapping, int index)
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{
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filler_t *filler = (filler_t*)mapping->a_ops->readpage;
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//do_page_cache_readahead(mapping, index, XXX, 64);
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cache_readahead(mapping, index);
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return read_cache_page(mapping, index, filler, NULL);
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}
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/* erase a specified part of the device */
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static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
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{
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struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
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struct page *page;
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int index = to >> PAGE_SHIFT; // page index
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int pages = len >> PAGE_SHIFT;
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u_long *p;
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u_long *max;
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while (pages) {
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page = page_readahead(mapping, index);
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if (!page)
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return -ENOMEM;
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if (IS_ERR(page))
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return PTR_ERR(page);
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max = (u_long*)page_address(page) + PAGE_SIZE;
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for (p=(u_long*)page_address(page); p<max; p++)
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if (*p != -1UL) {
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lock_page(page);
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memset(page_address(page), 0xff, PAGE_SIZE);
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set_page_dirty(page);
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unlock_page(page);
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break;
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}
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page_cache_release(page);
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pages--;
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index++;
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}
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return 0;
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}
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static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
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{
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struct block2mtd_dev *dev = mtd->priv;
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size_t from = instr->addr;
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size_t len = instr->len;
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int err;
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instr->state = MTD_ERASING;
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down(&dev->write_mutex);
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err = _block2mtd_erase(dev, from, len);
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up(&dev->write_mutex);
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if (err) {
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ERROR("erase failed err = %d", err);
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instr->state = MTD_ERASE_FAILED;
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} else
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instr->state = MTD_ERASE_DONE;
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instr->state = MTD_ERASE_DONE;
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mtd_erase_callback(instr);
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return err;
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}
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static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
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size_t *retlen, u_char *buf)
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{
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struct block2mtd_dev *dev = mtd->priv;
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struct page *page;
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int index = from >> PAGE_SHIFT;
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int offset = from & (PAGE_SHIFT-1);
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int cpylen;
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if (from > mtd->size)
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return -EINVAL;
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if (from + len > mtd->size)
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len = mtd->size - from;
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if (retlen)
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*retlen = 0;
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while (len) {
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if ((offset + len) > PAGE_SIZE)
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cpylen = PAGE_SIZE - offset; // multiple pages
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else
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cpylen = len; // this page
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len = len - cpylen;
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// Get page
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page = page_readahead(dev->blkdev->bd_inode->i_mapping, index);
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if (!page)
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return -ENOMEM;
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if (IS_ERR(page))
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return PTR_ERR(page);
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memcpy(buf, page_address(page) + offset, cpylen);
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page_cache_release(page);
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if (retlen)
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*retlen += cpylen;
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buf += cpylen;
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offset = 0;
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index++;
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}
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return 0;
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}
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/* write data to the underlying device */
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static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
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loff_t to, size_t len, size_t *retlen)
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{
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struct page *page;
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struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
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int index = to >> PAGE_SHIFT; // page index
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int offset = to & ~PAGE_MASK; // page offset
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int cpylen;
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if (retlen)
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*retlen = 0;
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while (len) {
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if ((offset+len) > PAGE_SIZE)
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cpylen = PAGE_SIZE - offset; // multiple pages
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else
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cpylen = len; // this page
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len = len - cpylen;
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// Get page
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page = page_readahead(mapping, index);
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if (!page)
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return -ENOMEM;
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if (IS_ERR(page))
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return PTR_ERR(page);
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if (memcmp(page_address(page)+offset, buf, cpylen)) {
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lock_page(page);
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memcpy(page_address(page) + offset, buf, cpylen);
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set_page_dirty(page);
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unlock_page(page);
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}
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page_cache_release(page);
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if (retlen)
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*retlen += cpylen;
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buf += cpylen;
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offset = 0;
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index++;
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}
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return 0;
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}
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static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
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size_t *retlen, const u_char *buf)
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{
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struct block2mtd_dev *dev = mtd->priv;
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int err;
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if (!len)
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return 0;
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if (to >= mtd->size)
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return -ENOSPC;
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if (to + len > mtd->size)
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len = mtd->size - to;
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down(&dev->write_mutex);
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err = _block2mtd_write(dev, buf, to, len, retlen);
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up(&dev->write_mutex);
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if (err > 0)
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err = 0;
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return err;
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}
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/* sync the device - wait until the write queue is empty */
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static void block2mtd_sync(struct mtd_info *mtd)
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{
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struct block2mtd_dev *dev = mtd->priv;
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sync_blockdev(dev->blkdev);
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return;
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}
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static void block2mtd_free_device(struct block2mtd_dev *dev)
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{
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if (!dev)
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return;
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kfree(dev->mtd.name);
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if (dev->blkdev) {
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invalidate_inode_pages(dev->blkdev->bd_inode->i_mapping);
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close_bdev_excl(dev->blkdev);
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}
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kfree(dev);
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}
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/* FIXME: ensure that mtd->size % erase_size == 0 */
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static struct block2mtd_dev *add_device(char *devname, int erase_size)
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{
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struct block_device *bdev;
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struct block2mtd_dev *dev;
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if (!devname)
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return NULL;
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dev = kmalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
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if (!dev)
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return NULL;
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memset(dev, 0, sizeof(*dev));
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/* Get a handle on the device */
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bdev = open_bdev_excl(devname, O_RDWR, NULL);
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if (IS_ERR(bdev)) {
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ERROR("error: cannot open device %s", devname);
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goto devinit_err;
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}
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dev->blkdev = bdev;
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if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
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ERROR("attempting to use an MTD device as a block device");
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goto devinit_err;
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}
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init_MUTEX(&dev->write_mutex);
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/* Setup the MTD structure */
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/* make the name contain the block device in */
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dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
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GFP_KERNEL);
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if (!dev->mtd.name)
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goto devinit_err;
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sprintf(dev->mtd.name, "block2mtd: %s", devname);
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dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
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dev->mtd.erasesize = erase_size;
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dev->mtd.type = MTD_RAM;
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dev->mtd.flags = MTD_CAP_RAM;
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dev->mtd.erase = block2mtd_erase;
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dev->mtd.write = block2mtd_write;
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dev->mtd.writev = default_mtd_writev;
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dev->mtd.sync = block2mtd_sync;
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dev->mtd.read = block2mtd_read;
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dev->mtd.readv = default_mtd_readv;
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dev->mtd.priv = dev;
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dev->mtd.owner = THIS_MODULE;
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if (add_mtd_device(&dev->mtd)) {
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/* Device didnt get added, so free the entry */
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goto devinit_err;
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}
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list_add(&dev->list, &blkmtd_device_list);
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INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
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dev->mtd.name + strlen("blkmtd: "),
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dev->mtd.erasesize >> 10, dev->mtd.erasesize);
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return dev;
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devinit_err:
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block2mtd_free_device(dev);
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return NULL;
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}
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static int ustrtoul(const char *cp, char **endp, unsigned int base)
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{
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unsigned long result = simple_strtoul(cp, endp, base);
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switch (**endp) {
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case 'G' :
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result *= 1024;
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case 'M':
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result *= 1024;
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case 'k':
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result *= 1024;
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/* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
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if ((*endp)[1] == 'i')
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(*endp) += 2;
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}
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return result;
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}
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static int parse_num32(u32 *num32, const char *token)
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{
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char *endp;
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unsigned long n;
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n = ustrtoul(token, &endp, 0);
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if (*endp)
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return -EINVAL;
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*num32 = n;
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return 0;
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}
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static int parse_name(char **pname, const char *token, size_t limit)
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{
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size_t len;
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char *name;
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len = strlen(token) + 1;
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if (len > limit)
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return -ENOSPC;
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name = kmalloc(len, GFP_KERNEL);
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if (!name)
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return -ENOMEM;
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strcpy(name, token);
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*pname = name;
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return 0;
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}
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static inline void kill_final_newline(char *str)
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{
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char *newline = strrchr(str, '\n');
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if (newline && !newline[1])
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*newline = 0;
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}
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#define parse_err(fmt, args...) do { \
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ERROR("block2mtd: " fmt "\n", ## args); \
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return 0; \
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} while (0)
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static int block2mtd_setup(const char *val, struct kernel_param *kp)
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{
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char buf[80+12], *str=buf; /* 80 for device, 12 for erase size */
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char *token[2];
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char *name;
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u32 erase_size = PAGE_SIZE;
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int i, ret;
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if (strnlen(val, sizeof(buf)) >= sizeof(buf))
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parse_err("parameter too long");
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strcpy(str, val);
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kill_final_newline(str);
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for (i=0; i<2; i++)
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token[i] = strsep(&str, ",");
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if (str)
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parse_err("too many arguments");
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if (!token[0])
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parse_err("no argument");
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ret = parse_name(&name, token[0], 80);
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if (ret == -ENOMEM)
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parse_err("out of memory");
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if (ret == -ENOSPC)
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parse_err("name too long");
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if (ret)
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return 0;
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if (token[1]) {
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ret = parse_num32(&erase_size, token[1]);
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if (ret)
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parse_err("illegal erase size");
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}
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add_device(name, erase_size);
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return 0;
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}
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module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
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MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
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static int __init block2mtd_init(void)
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{
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INFO("version " VERSION);
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return 0;
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}
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static void __devexit block2mtd_exit(void)
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{
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struct list_head *pos, *next;
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/* Remove the MTD devices */
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list_for_each_safe(pos, next, &blkmtd_device_list) {
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struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
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block2mtd_sync(&dev->mtd);
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del_mtd_device(&dev->mtd);
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INFO("mtd%d: [%s] removed", dev->mtd.index,
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dev->mtd.name + strlen("blkmtd: "));
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list_del(&dev->list);
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block2mtd_free_device(dev);
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}
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}
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module_init(block2mtd_init);
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module_exit(block2mtd_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
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MODULE_DESCRIPTION("Emulate an MTD using a block device");
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