![Felix Fietkau](/assets/img/avatar_default.png)
Ensures that block2mtd is triggered after the block devices are enumerated at boot time. This issue is seen on BCM2835 (Raspberry Pi) systems when mounting JFFS2 block2mtd filesystems, probably because of the delay on enumerating a USB MMC card reader. Signed-off-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: Rodrigo Freire <rfreire@redhat.com> Signed-off-by: Herton Krzesinski <herton@redhat.com> Signed-off-by: Brian Norris <computersforpeace@gmail.com>
501 lines
11 KiB
C
501 lines
11 KiB
C
/*
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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) 2004-2006 Joern Engel <joern@wh.fh-wedel.de>
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*
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* Licence: GPL
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/*
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* When the first attempt at device initialization fails, we may need to
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* wait a little bit and retry. This timeout, by default 3 seconds, gives
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* device time to start up. Required on BCM2708 and a few other chipsets.
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*/
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#define MTD_DEFAULT_TIMEOUT 3
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#include <linux/module.h>
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#include <linux/delay.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/mutex.h>
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#include <linux/mount.h>
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#include <linux/slab.h>
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#include <linux/major.h>
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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 mutex 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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static struct page *page_read(struct address_space *mapping, int index)
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{
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return read_mapping_page(mapping, index, 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_read(mapping, index);
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if (IS_ERR(page))
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return PTR_ERR(page);
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max = page_address(page) + PAGE_SIZE;
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for (p=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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balance_dirty_pages_ratelimited(mapping);
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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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mutex_lock(&dev->write_mutex);
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err = _block2mtd_erase(dev, from, len);
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mutex_unlock(&dev->write_mutex);
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if (err) {
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pr_err("erase failed err = %d\n", 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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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_SIZE-1);
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int cpylen;
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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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page = page_read(dev->blkdev->bd_inode->i_mapping, index);
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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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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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page = page_read(mapping, index);
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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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balance_dirty_pages_ratelimited(mapping);
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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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mutex_lock(&dev->write_mutex);
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err = _block2mtd_write(dev, buf, to, len, retlen);
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mutex_unlock(&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_mapping_pages(dev->blkdev->bd_inode->i_mapping,
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0, -1);
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blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
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}
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kfree(dev);
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}
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static struct block2mtd_dev *add_device(char *devname, int erase_size,
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int timeout)
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{
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#ifndef MODULE
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int i;
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#endif
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const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
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struct block_device *bdev = ERR_PTR(-ENODEV);
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struct block2mtd_dev *dev;
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char *name;
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if (!devname)
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return NULL;
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dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
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if (!dev)
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return NULL;
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/* Get a handle on the device */
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bdev = blkdev_get_by_path(devname, mode, dev);
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#ifndef MODULE
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/*
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* We might not have the root device mounted at this point.
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* Try to resolve the device name by other means.
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*/
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for (i = 0; IS_ERR(bdev) && i <= timeout; i++) {
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dev_t devt;
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if (i)
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/*
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* Calling wait_for_device_probe in the first loop
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* was not enough, sleep for a bit in subsequent
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* go-arounds.
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*/
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msleep(1000);
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wait_for_device_probe();
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devt = name_to_dev_t(devname);
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if (!devt)
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continue;
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bdev = blkdev_get_by_dev(devt, mode, dev);
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}
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#endif
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if (IS_ERR(bdev)) {
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pr_err("error: cannot open device %s\n", devname);
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goto err_free_block2mtd;
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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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pr_err("attempting to use an MTD device as a block device\n");
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goto err_free_block2mtd;
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}
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if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
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pr_err("erasesize must be a divisor of device size\n");
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goto err_free_block2mtd;
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}
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mutex_init(&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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name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
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if (!name)
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goto err_destroy_mutex;
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dev->mtd.name = name;
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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.writesize = 1;
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dev->mtd.writebufsize = PAGE_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._sync = block2mtd_sync;
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dev->mtd._read = block2mtd_read;
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dev->mtd.priv = dev;
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dev->mtd.owner = THIS_MODULE;
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if (mtd_device_register(&dev->mtd, NULL, 0)) {
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/* Device didn't get added, so free the entry */
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goto err_destroy_mutex;
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}
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list_add(&dev->list, &blkmtd_device_list);
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pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",
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dev->mtd.index,
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dev->mtd.name + strlen("block2mtd: "),
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dev->mtd.erasesize >> 10, dev->mtd.erasesize);
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return dev;
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err_destroy_mutex:
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mutex_destroy(&dev->write_mutex);
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err_free_block2mtd:
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block2mtd_free_device(dev);
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return NULL;
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}
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/* This function works similar to reguler strtoul. In addition, it
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* allows some suffixes for a more human-readable number format:
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* ki, Ki, kiB, KiB - multiply result with 1024
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* Mi, MiB - multiply result with 1024^2
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* Gi, GiB - multiply result with 1024^3
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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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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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if ((*endp)[2] == 'B')
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(*endp) += 3;
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else
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(*endp) += 2;
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}
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}
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return result;
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}
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static int parse_num(size_t *num, const char *token)
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{
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char *endp;
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size_t n;
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n = (size_t) ustrtoul(token, &endp, 0);
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if (*endp)
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return -EINVAL;
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*num = n;
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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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#ifndef MODULE
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static int block2mtd_init_called = 0;
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/* 80 for device, 12 for erase size */
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static char block2mtd_paramline[80 + 12];
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#endif
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static int block2mtd_setup2(const char *val)
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{
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/* 80 for device, 12 for erase size, 80 for name, 8 for timeout */
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char buf[80 + 12 + 80 + 8];
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char *str = buf;
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char *token[2];
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char *name;
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size_t erase_size = PAGE_SIZE;
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unsigned long timeout = MTD_DEFAULT_TIMEOUT;
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int i, ret;
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if (strnlen(val, sizeof(buf)) >= sizeof(buf)) {
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pr_err("parameter too long\n");
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return 0;
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}
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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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pr_err("too many arguments\n");
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return 0;
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}
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if (!token[0]) {
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pr_err("no argument\n");
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return 0;
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}
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name = token[0];
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if (strlen(name) + 1 > 80) {
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pr_err("device name too long\n");
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return 0;
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}
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if (token[1]) {
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ret = parse_num(&erase_size, token[1]);
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if (ret) {
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pr_err("illegal erase size\n");
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return 0;
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}
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}
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add_device(name, erase_size, timeout);
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return 0;
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}
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static int block2mtd_setup(const char *val, struct kernel_param *kp)
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{
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#ifdef MODULE
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return block2mtd_setup2(val);
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#else
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/* If more parameters are later passed in via
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/sys/module/block2mtd/parameters/block2mtd
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and block2mtd_init() has already been called,
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we can parse the argument now. */
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if (block2mtd_init_called)
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return block2mtd_setup2(val);
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/* During early boot stage, we only save the parameters
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here. We must parse them later: if the param passed
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from kernel boot command line, block2mtd_setup() is
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called so early that it is not possible to resolve
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the device (even kmalloc() fails). Deter that work to
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block2mtd_setup2(). */
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strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
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return 0;
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#endif
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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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int ret = 0;
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#ifndef MODULE
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if (strlen(block2mtd_paramline))
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ret = block2mtd_setup2(block2mtd_paramline);
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block2mtd_init_called = 1;
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#endif
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return ret;
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}
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static void 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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mtd_device_unregister(&dev->mtd);
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mutex_destroy(&dev->write_mutex);
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pr_info("mtd%d: [%s] removed\n",
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dev->mtd.index,
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dev->mtd.name + strlen("block2mtd: "));
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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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late_initcall(block2mtd_init);
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module_exit(block2mtd_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
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MODULE_DESCRIPTION("Emulate an MTD using a block device");
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