--- /dev/null
+/*
+ * block2mtd.c - create an mtd from a block device
+ *
+ * Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk>
+ * Copyright (C) 2004-2006 Joern Engel <joern@wh.fh-wedel.de>
+ *
+ * Licence: GPL
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+/*
+ * When the first attempt at device initialization fails, we may need to
+ * wait a little bit and retry. This timeout, by default 3 seconds, gives
+ * device time to start up. Required on BCM2708 and a few other chipsets.
+ */
+#define MTD_DEFAULT_TIMEOUT 3
+
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/pagemap.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mutex.h>
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/major.h>
+
+/* Info for the block device */
+struct block2mtd_dev {
+ struct list_head list;
+ struct block_device *blkdev;
+ struct mtd_info mtd;
+ struct mutex write_mutex;
+};
+
+
+/* Static info about the MTD, used in cleanup_module */
+static LIST_HEAD(blkmtd_device_list);
+
+
+static struct page *page_read(struct address_space *mapping, int index)
+{
+ return read_mapping_page(mapping, index, NULL);
+}
+
+/* erase a specified part of the device */
+static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
+{
+ struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
+ struct page *page;
+ int index = to >> PAGE_SHIFT; // page index
+ int pages = len >> PAGE_SHIFT;
+ u_long *p;
+ u_long *max;
+
+ while (pages) {
+ page = page_read(mapping, index);
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+
+ max = page_address(page) + PAGE_SIZE;
+ for (p=page_address(page); p<max; p++)
+ if (*p != -1UL) {
+ lock_page(page);
+ memset(page_address(page), 0xff, PAGE_SIZE);
+ set_page_dirty(page);
+ unlock_page(page);
+ balance_dirty_pages_ratelimited(mapping);
+ break;
+ }
+
+ page_cache_release(page);
+ pages--;
+ index++;
+ }
+ return 0;
+}
+static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
+{
+ struct block2mtd_dev *dev = mtd->priv;
+ size_t from = instr->addr;
+ size_t len = instr->len;
+ int err;
+
+ instr->state = MTD_ERASING;
+ mutex_lock(&dev->write_mutex);
+ err = _block2mtd_erase(dev, from, len);
+ mutex_unlock(&dev->write_mutex);
+ if (err) {
+ pr_err("erase failed err = %d\n", err);
+ instr->state = MTD_ERASE_FAILED;
+ } else
+ instr->state = MTD_ERASE_DONE;
+
+ mtd_erase_callback(instr);
+ return err;
+}
+
+
+static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
+ size_t *retlen, u_char *buf)
+{
+ struct block2mtd_dev *dev = mtd->priv;
+ struct page *page;
+ int index = from >> PAGE_SHIFT;
+ int offset = from & (PAGE_SIZE-1);
+ int cpylen;
+
+ while (len) {
+ if ((offset + len) > PAGE_SIZE)
+ cpylen = PAGE_SIZE - offset; // multiple pages
+ else
+ cpylen = len; // this page
+ len = len - cpylen;
+
+ page = page_read(dev->blkdev->bd_inode->i_mapping, index);
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+
+ memcpy(buf, page_address(page) + offset, cpylen);
+ page_cache_release(page);
+
+ if (retlen)
+ *retlen += cpylen;
+ buf += cpylen;
+ offset = 0;
+ index++;
+ }
+ return 0;
+}
+
+
+/* write data to the underlying device */
+static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
+ loff_t to, size_t len, size_t *retlen)
+{
+ struct page *page;
+ struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
+ int index = to >> PAGE_SHIFT; // page index
+ int offset = to & ~PAGE_MASK; // page offset
+ int cpylen;
+
+ while (len) {
+ if ((offset+len) > PAGE_SIZE)
+ cpylen = PAGE_SIZE - offset; // multiple pages
+ else
+ cpylen = len; // this page
+ len = len - cpylen;
+
+ page = page_read(mapping, index);
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+
+ if (memcmp(page_address(page)+offset, buf, cpylen)) {
+ lock_page(page);
+ memcpy(page_address(page) + offset, buf, cpylen);
+ set_page_dirty(page);
+ unlock_page(page);
+ balance_dirty_pages_ratelimited(mapping);
+ }
+ page_cache_release(page);
+
+ if (retlen)
+ *retlen += cpylen;
+
+ buf += cpylen;
+ offset = 0;
+ index++;
+ }
+ return 0;
+}
+
+
+static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
+ size_t *retlen, const u_char *buf)
+{
+ struct block2mtd_dev *dev = mtd->priv;
+ int err;
+
+ mutex_lock(&dev->write_mutex);
+ err = _block2mtd_write(dev, buf, to, len, retlen);
+ mutex_unlock(&dev->write_mutex);
+ if (err > 0)
+ err = 0;
+ return err;
+}
+
+
+/* sync the device - wait until the write queue is empty */
+static void block2mtd_sync(struct mtd_info *mtd)
+{
+ struct block2mtd_dev *dev = mtd->priv;
+ sync_blockdev(dev->blkdev);
+ return;
+}
+
+
+static void block2mtd_free_device(struct block2mtd_dev *dev)
+{
+ if (!dev)
+ return;
+
+ kfree(dev->mtd.name);
+
+ if (dev->blkdev) {
+ invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
+ 0, -1);
+ blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
+ }
+
+ kfree(dev);
+}
+
+
+static struct block2mtd_dev *add_device(char *devname, int erase_size,
+ int timeout)
+{
+#ifndef MODULE
+ int i;
+#endif
+ const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
+ struct block_device *bdev = ERR_PTR(-ENODEV);
+ struct block2mtd_dev *dev;
+ char *name;
+
+ if (!devname)
+ return NULL;
+
+ dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
+ if (!dev)
+ return NULL;
+
+ /* Get a handle on the device */
+ bdev = blkdev_get_by_path(devname, mode, dev);
+
+#ifndef MODULE
+ /*
+ * We might not have the root device mounted at this point.
+ * Try to resolve the device name by other means.
+ */
+ for (i = 0; IS_ERR(bdev) && i <= timeout; i++) {
+ dev_t devt;
+
+ if (i)
+ /*
+ * Calling wait_for_device_probe in the first loop
+ * was not enough, sleep for a bit in subsequent
+ * go-arounds.
+ */
+ msleep(1000);
+ wait_for_device_probe();
+
+ devt = name_to_dev_t(devname);
+ if (!devt)
+ continue;
+ bdev = blkdev_get_by_dev(devt, mode, dev);
+ }
+#endif
+
+ if (IS_ERR(bdev)) {
+ pr_err("error: cannot open device %s\n", devname);
+ goto err_free_block2mtd;
+ }
+ dev->blkdev = bdev;
+
+ if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
+ pr_err("attempting to use an MTD device as a block device\n");
+ goto err_free_block2mtd;
+ }
+
+ if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
+ pr_err("erasesize must be a divisor of device size\n");
+ goto err_free_block2mtd;
+ }
+
+ mutex_init(&dev->write_mutex);
+
+ /* Setup the MTD structure */
+ /* make the name contain the block device in */
+ name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
+ if (!name)
+ goto err_destroy_mutex;
+
+ dev->mtd.name = name;
+
+ dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
+ dev->mtd.erasesize = erase_size;
+ dev->mtd.writesize = 1;
+ dev->mtd.writebufsize = PAGE_SIZE;
+ dev->mtd.type = MTD_RAM;
+ dev->mtd.flags = MTD_CAP_RAM;
+ dev->mtd._erase = block2mtd_erase;
+ dev->mtd._write = block2mtd_write;
+ dev->mtd._sync = block2mtd_sync;
+ dev->mtd._read = block2mtd_read;
+ dev->mtd.priv = dev;
+ dev->mtd.owner = THIS_MODULE;
+
+ if (mtd_device_register(&dev->mtd, NULL, 0)) {
+ /* Device didn't get added, so free the entry */
+ goto err_destroy_mutex;
+ }
+
+ list_add(&dev->list, &blkmtd_device_list);
+ pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",
+ dev->mtd.index,
+ dev->mtd.name + strlen("block2mtd: "),
+ dev->mtd.erasesize >> 10, dev->mtd.erasesize);
+ return dev;
+
+err_destroy_mutex:
+ mutex_destroy(&dev->write_mutex);
+err_free_block2mtd:
+ block2mtd_free_device(dev);
+ return NULL;
+}
+
+
+/* This function works similar to reguler strtoul. In addition, it
+ * allows some suffixes for a more human-readable number format:
+ * ki, Ki, kiB, KiB - multiply result with 1024
+ * Mi, MiB - multiply result with 1024^2
+ * Gi, GiB - multiply result with 1024^3
+ */
+static int ustrtoul(const char *cp, char **endp, unsigned int base)
+{
+ unsigned long result = simple_strtoul(cp, endp, base);
+ switch (**endp) {
+ case 'G' :
+ result *= 1024;
+ case 'M':
+ result *= 1024;
+ case 'K':
+ case 'k':
+ result *= 1024;
+ /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
+ if ((*endp)[1] == 'i') {
+ if ((*endp)[2] == 'B')
+ (*endp) += 3;
+ else
+ (*endp) += 2;
+ }
+ }
+ return result;
+}
+
+
+static int parse_num(size_t *num, const char *token)
+{
+ char *endp;
+ size_t n;
+
+ n = (size_t) ustrtoul(token, &endp, 0);
+ if (*endp)
+ return -EINVAL;
+
+ *num = n;
+ return 0;
+}
+
+
+static inline void kill_final_newline(char *str)
+{
+ char *newline = strrchr(str, '\n');
+ if (newline && !newline[1])
+ *newline = 0;
+}
+
+
+#ifndef MODULE
+static int block2mtd_init_called = 0;
+/* 80 for device, 12 for erase size */
+static char block2mtd_paramline[80 + 12];
+#endif
+
+static int block2mtd_setup2(const char *val)
+{
+ /* 80 for device, 12 for erase size, 80 for name, 8 for timeout */
+ char buf[80 + 12 + 80 + 8];
+ char *str = buf;
+ char *token[2];
+ char *name;
+ size_t erase_size = PAGE_SIZE;
+ unsigned long timeout = MTD_DEFAULT_TIMEOUT;
+ int i, ret;
+
+ if (strnlen(val, sizeof(buf)) >= sizeof(buf)) {
+ pr_err("parameter too long\n");
+ return 0;
+ }
+
+ strcpy(str, val);
+ kill_final_newline(str);
+
+ for (i = 0; i < 2; i++)
+ token[i] = strsep(&str, ",");
+
+ if (str) {
+ pr_err("too many arguments\n");
+ return 0;
+ }
+
+ if (!token[0]) {
+ pr_err("no argument\n");
+ return 0;
+ }
+
+ name = token[0];
+ if (strlen(name) + 1 > 80) {
+ pr_err("device name too long\n");
+ return 0;
+ }
+
+ if (token[1]) {
+ ret = parse_num(&erase_size, token[1]);
+ if (ret) {
+ pr_err("illegal erase size\n");
+ return 0;
+ }
+ }
+
+ add_device(name, erase_size, timeout);
+
+ return 0;
+}
+
+
+static int block2mtd_setup(const char *val, struct kernel_param *kp)
+{
+#ifdef MODULE
+ return block2mtd_setup2(val);
+#else
+ /* If more parameters are later passed in via
+ /sys/module/block2mtd/parameters/block2mtd
+ and block2mtd_init() has already been called,
+ we can parse the argument now. */
+
+ if (block2mtd_init_called)
+ return block2mtd_setup2(val);
+
+ /* During early boot stage, we only save the parameters
+ here. We must parse them later: if the param passed
+ from kernel boot command line, block2mtd_setup() is
+ called so early that it is not possible to resolve
+ the device (even kmalloc() fails). Deter that work to
+ block2mtd_setup2(). */
+
+ strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
+
+ return 0;
+#endif
+}
+
+
+module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
+MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
+
+static int __init block2mtd_init(void)
+{
+ int ret = 0;
+
+#ifndef MODULE
+ if (strlen(block2mtd_paramline))
+ ret = block2mtd_setup2(block2mtd_paramline);
+ block2mtd_init_called = 1;
+#endif
+
+ return ret;
+}
+
+
+static void block2mtd_exit(void)
+{
+ struct list_head *pos, *next;
+
+ /* Remove the MTD devices */
+ list_for_each_safe(pos, next, &blkmtd_device_list) {
+ struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
+ block2mtd_sync(&dev->mtd);
+ mtd_device_unregister(&dev->mtd);
+ mutex_destroy(&dev->write_mutex);
+ pr_info("mtd%d: [%s] removed\n",
+ dev->mtd.index,
+ dev->mtd.name + strlen("block2mtd: "));
+ list_del(&dev->list);
+ block2mtd_free_device(dev);
+ }
+}
+
+late_initcall(block2mtd_init);
+module_exit(block2mtd_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
+MODULE_DESCRIPTION("Emulate an MTD using a block device");
Code Review / kvmfornfv.git / blobdiff