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mirror of git://projects.qi-hardware.com/openwrt-xburst.git synced 2024-12-25 03:13:20 +02:00

add refresh ioctl to mtd (for rescanning partitions after reflash)

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@8438 3c298f89-4303-0410-b956-a3cf2f4a3e73
This commit is contained in:
nbd 2007-08-19 21:53:17 +00:00
parent e76b8552e2
commit 7b7737acaf
2 changed files with 537 additions and 68 deletions

View File

@ -1,8 +1,8 @@
Index: linux/drivers/mtd/Kconfig
Index: linux-2.6.22.1/drivers/mtd/Kconfig
===================================================================
--- linux.orig/drivers/mtd/Kconfig
+++ linux/drivers/mtd/Kconfig
@@ -47,6 +47,16 @@ config MTD_PARTITIONS
--- linux-2.6.22.1.orig/drivers/mtd/Kconfig 2007-08-19 23:30:07.068115074 +0200
+++ linux-2.6.22.1/drivers/mtd/Kconfig 2007-08-19 23:31:43.961636725 +0200
@@ -47,6 +47,16 @@
devices. Partitioning on NFTL 'devices' is a different - that's the
'normal' form of partitioning used on a block device.
@ -19,10 +19,10 @@ Index: linux/drivers/mtd/Kconfig
config MTD_REDBOOT_PARTS
tristate "RedBoot partition table parsing"
depends on MTD_PARTITIONS
Index: linux/drivers/mtd/mtdpart.c
Index: linux-2.6.22.1/drivers/mtd/mtdpart.c
===================================================================
--- linux.orig/drivers/mtd/mtdpart.c
+++ linux/drivers/mtd/mtdpart.c
--- linux-2.6.22.1.orig/drivers/mtd/mtdpart.c 2007-08-19 23:30:07.076115531 +0200
+++ linux-2.6.22.1/drivers/mtd/mtdpart.c 2007-08-19 23:31:44.065642653 +0200
@@ -20,6 +20,8 @@
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
@ -32,7 +32,16 @@ Index: linux/drivers/mtd/mtdpart.c
/* Our partition linked list */
static LIST_HEAD(mtd_partitions);
@@ -308,6 +310,265 @@ int del_mtd_partitions(struct mtd_info *
@@ -39,7 +41,7 @@
* the pointer to that structure with this macro.
*/
#define PART(x) ((struct mtd_part *)(x))
-
+#define IS_PART(mtd) (mtd->read == part_read)
/*
* MTD methods which simply translate the effective address and pass through
@@ -308,6 +310,312 @@
return 0;
}
@ -66,6 +75,7 @@ Index: linux/drivers/mtd/mtdpart.c
+
+ slave->mtd.read = part_read;
+ slave->mtd.write = part_write;
+ slave->mtd.refresh_device = part->refresh_partition;
+
+ if(master->point && master->unpoint){
+ slave->mtd.point = part_point;
@ -207,98 +217,144 @@ Index: linux/drivers/mtd/mtdpart.c
+
+#ifdef CONFIG_MTD_ROOTFS_SPLIT
+#define ROOTFS_SPLIT_NAME "rootfs_data"
+static int split_squashfs(struct mtd_info *master, struct mtd_partition *old,
+ struct mtd_partition **new)
+#define ROOTFS_REMOVED_NAME "<removed>"
+static int split_squashfs(struct mtd_info *master, int offset, int *split_offset)
+{
+ struct mtd_partition *part = NULL;
+ int len;
+ char buf[512];
+ struct squashfs_super_block *sb = (struct squashfs_super_block *) buf;
+ int ret;
+ int len, ret;
+
+ ret = master->read(master, old->offset, sizeof(*sb), &len, buf);
+ if (ret) {
+ ret = master->read(master, offset, sizeof(*sb), &len, buf);
+ if (ret || (len != sizeof(*sb))) {
+ printk(KERN_ALERT "split_squashfs: error occured while reading "
+ "from \"%s\"\n", master->name);
+ goto out;
+ }
+
+ if (len != sizeof(*sb)) {
+ printk(KERN_ALERT "split_squashfs: unable to read superblock "
+ "from \"%s\"\n", master->name);
+ ret=-1;
+ goto out;
+ return -EINVAL;
+ }
+
+ if (*((u32 *) buf) != SQUASHFS_MAGIC) {
+ printk(KERN_ALERT "split_squasfs: no squashfs found in \"%s\"\n",
+ master->name);
+ ret=0;
+ goto out;
+ *split_offset = 0;
+ return 0;
+ }
+
+ if (sb->bytes_used <= 0) {
+ printk(KERN_ALERT "split_squashfs: squashfs is empty in \"%s\"\n",
+ master->name);
+ ret=0;
+ goto out;
+ *split_offset = 0;
+ return 0;
+ }
+
+ part = kmalloc(sizeof(*part)+sizeof(ROOTFS_SPLIT_NAME)+1, GFP_KERNEL);
+ if (part == NULL) {
+ printk(KERN_INFO "split_squashfs: no memory for partition \"%s\"\n",
+ ROOTFS_SPLIT_NAME);
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ memcpy(part, old, sizeof(*part));
+ part->name = (unsigned char *)&part[1];
+ strcpy(part->name, ROOTFS_SPLIT_NAME);
+
+ len = (u32) sb->bytes_used;
+ len += (part->offset & 0x000fffff);
+ len += (offset & 0x000fffff);
+ len += (master->erasesize - 1);
+ len &= ~(master->erasesize - 1);
+ len -= (part->offset & 0x000fffff);
+ part->offset += len;
+ part->size -= len;
+ len -= (offset & 0x000fffff);
+ *split_offset = offset + len;
+
+ ret = 0;
+
+out:
+ *new = part;
+ return ret;
+ return 0;
+}
+
+static int split_rootfs_data(struct mtd_info *master, struct mtd_partition *part,
+static int split_rootfs_data(struct mtd_info *master, struct mtd_info *rpart, struct mtd_partition *part,
+ int index)
+{
+ struct mtd_partition *dpart;
+ struct mtd_part *slave = NULL;
+ int split_offset = 0;
+ int ret;
+
+ ret = split_squashfs(master, part, &dpart);
+ ret = split_squashfs(master, part->offset, &split_offset);
+ if (ret)
+ return ret;
+
+ if (split_offset <= 0)
+ return 0;
+
+ dpart = kmalloc(sizeof(*part)+sizeof(ROOTFS_SPLIT_NAME)+1, GFP_KERNEL);
+ if (dpart == NULL) {
+ printk(KERN_INFO "split_squashfs: no memory for partition \"%s\"\n",
+ ROOTFS_SPLIT_NAME);
+ return -ENOMEM;
+ }
+
+ memcpy(dpart, part, sizeof(*part));
+ dpart->name = (unsigned char *)&dpart[1];
+ strcpy(dpart->name, ROOTFS_SPLIT_NAME);
+
+ dpart->size -= split_offset - dpart->offset;
+ dpart->offset = split_offset;
+
+ if (dpart == NULL)
+ return 1;
+
+ printk(KERN_INFO "mtd: partition \"%s\" created automatically, ofs=%X, len=%X \n",
+ ROOTFS_SPLIT_NAME, dpart->offset, dpart->size);
+
+ ret = add_one_partition(master, dpart, index, NULL);
+ ret = add_one_partition(master, dpart, index, &slave);
+ if (ret)
+ kfree(dpart);
+ else if (slave)
+ rpart->split = &slave->mtd;
+
+ return ret;
+}
+
+static int refresh_rootfs_split(struct mtd_info *mtd)
+{
+ struct mtd_partition tpart;
+ struct mtd_part *part;
+ int index = 0;
+ int offset, size;
+ int ret;
+
+ part = PART(mtd);
+
+ /* check for the new squashfs offset first */
+ ret = split_squashfs(part->master, part->offset, &offset);
+ if (ret)
+ return ret;
+
+ if ((offset > 0) && !mtd->split) {
+ printk(KERN_INFO "%s: creating new split partition for \"%s\"\n", __func__, mtd->name);
+ /* if we don't have a rootfs split partition, create a new one */
+ tpart.name = mtd->name;
+ tpart.size = mtd->size;
+ tpart.offset = part->offset;
+
+ /* find the index of the last partition */
+ if (!list_empty(&mtd_partitions))
+ index = list_first_entry(&mtd_partitions, struct mtd_part, list)->index + 1;
+
+ return split_rootfs_data(part->master, &part->mtd, &tpart, index);
+ } else if ((offset > 0) && mtd->split) {
+ /* update the offsets of the existing partition */
+ size = mtd->size + part->offset - offset;
+
+ part = PART(mtd->split);
+ part->offset = offset;
+ part->mtd.size = size;
+ printk(KERN_INFO "%s: %s partition \"" ROOTFS_SPLIT_NAME "\", offset: 0x%06x (0x%06x)\n",
+ __func__, (!strcmp(part->mtd.name, ROOTFS_SPLIT_NAME) ? "updating" : "creating"),
+ part->offset, part->mtd.size);
+ strcpy(part->mtd.name, ROOTFS_SPLIT_NAME);
+ } else if ((offset <= 0) && mtd->split) {
+ printk(KERN_INFO "%s: removing partition \"%s\"\n", __func__, mtd->split->name);
+
+ /* mark existing partition as removed */
+ part = PART(mtd->split);
+ strcpy(part->mtd.name, ROOTFS_REMOVED_NAME);
+ part->offset = 0;
+ part->mtd.size = 0;
+ }
+
+ return 0;
+}
+#endif /* CONFIG_MTD_ROOTFS_SPLIT */
+
/*
* This function, given a master MTD object and a partition table, creates
* and registers slave MTD objects which are bound to the master according to
@@ -320,168 +581,31 @@ int add_mtd_partitions(struct mtd_info *
@@ -320,168 +628,31 @@
int nbparts)
{
struct mtd_part *slave;
@ -423,7 +479,20 @@ Index: linux/drivers/mtd/mtdpart.c
- if (slave->mtd.erasesize < regions[i].erasesize) {
- slave->mtd.erasesize = regions[i].erasesize;
- }
- }
+ for (i = 0, j = 0; i < nbparts; i++) {
+ part = (struct mtd_partition *) &parts[i];
+ ret = add_one_partition(master, part, j, &slave);
+ if (ret)
+ return ret;
+ j++;
+
+ if (strcmp(part->name, "rootfs") == 0 && slave->registered) {
+#ifdef CONFIG_MTD_ROOTFS_ROOT_DEV
+ if (ROOT_DEV == 0) {
+ printk(KERN_NOTICE "mtd: partition \"rootfs\" "
+ "set to be root filesystem\n");
+ ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, slave->mtd.index);
}
- } else {
- /* Single erase size */
- slave->mtd.erasesize = master->erasesize;
@ -453,20 +522,7 @@ Index: linux/drivers/mtd/mtdpart.c
- offs + slave->offset))
- slave->mtd.ecc_stats.badblocks++;
- offs += slave->mtd.erasesize;
+ for (i = 0, j = 0; i < nbparts; i++) {
+ part = (struct mtd_partition *) &parts[i];
+ ret = add_one_partition(master, part, j, &slave);
+ if (ret)
+ return ret;
+ j++;
+
+ if (strcmp(part->name, "rootfs") == 0 && slave->registered) {
+#ifdef CONFIG_MTD_ROOTFS_ROOT_DEV
+ if (ROOT_DEV == 0) {
+ printk(KERN_NOTICE "mtd: partition \"rootfs\" "
+ "set to be root filesystem\n");
+ ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, slave->mtd.index);
}
- }
- }
-
- if(parts[i].mtdp)
@ -481,10 +537,423 @@ Index: linux/drivers/mtd/mtdpart.c
- slave->registered = 1;
+#endif
+#ifdef CONFIG_MTD_ROOTFS_SPLIT
+ ret = split_rootfs_data(master, part, j);
+ ret = split_rootfs_data(master, &slave->mtd, part, j);
+ if (ret == 0)
+ j++;
+#endif
}
}
@@ -557,7 +728,33 @@
return ret;
}
+int refresh_mtd_partitions(struct mtd_info *mtd)
+{
+ int ret = 0;
+
+ if (IS_PART(mtd)) {
+ struct mtd_part *part;
+ struct mtd_info *master;
+
+ part = PART(mtd);
+ master = part->master;
+ if (master->refresh_device)
+ ret = master->refresh_device(master);
+ }
+
+ if (!ret && mtd->refresh_device)
+ ret = mtd->refresh_device(mtd);
+
+#ifdef CONFIG_MTD_ROOTFS_SPLIT
+ if (!ret && IS_PART(mtd) && !strcmp(mtd->name, "rootfs"))
+ refresh_rootfs_split(mtd);
+#endif
+
+ return 0;
+}
+
EXPORT_SYMBOL_GPL(parse_mtd_partitions);
+EXPORT_SYMBOL_GPL(refresh_mtd_partitions);
EXPORT_SYMBOL_GPL(register_mtd_parser);
EXPORT_SYMBOL_GPL(deregister_mtd_parser);
Index: linux-2.6.22.1/drivers/mtd/devices/block2mtd.c
===================================================================
--- linux-2.6.22.1.orig/drivers/mtd/devices/block2mtd.c 2007-08-19 23:30:49.794549917 +0200
+++ linux-2.6.22.1/drivers/mtd/devices/block2mtd.c 2007-08-19 23:31:44.025640373 +0200
@@ -34,6 +34,8 @@
struct block_device *blkdev;
struct mtd_info mtd;
struct mutex write_mutex;
+ rwlock_t bdev_mutex;
+ char devname[0];
};
@@ -86,6 +88,12 @@
size_t len = instr->len;
int err;
+ read_lock(&dev->bdev_mutex);
+ if (!dev->blkdev) {
+ err = -EINVAL;
+ goto done;
+ }
+
instr->state = MTD_ERASING;
mutex_lock(&dev->write_mutex);
err = _block2mtd_erase(dev, from, len);
@@ -98,6 +106,10 @@
instr->state = MTD_ERASE_DONE;
mtd_erase_callback(instr);
+
+done:
+ read_unlock(&dev->bdev_mutex);
+
return err;
}
@@ -109,10 +121,14 @@
struct page *page;
int index = from >> PAGE_SHIFT;
int offset = from & (PAGE_SIZE-1);
- int cpylen;
+ int cpylen, err = 0;
+
+ read_lock(&dev->bdev_mutex);
+ if (!dev->blkdev || (from > mtd->size)) {
+ err = -EINVAL;
+ goto done;
+ }
- if (from > mtd->size)
- return -EINVAL;
if (from + len > mtd->size)
len = mtd->size - from;
@@ -127,10 +143,14 @@
len = len - cpylen;
page = page_read(dev->blkdev->bd_inode->i_mapping, index);
- if (!page)
- return -ENOMEM;
- if (IS_ERR(page))
- return PTR_ERR(page);
+ if (!page) {
+ err = -ENOMEM;
+ goto done;
+ }
+ if (IS_ERR(page)) {
+ err = PTR_ERR(page);
+ goto done;
+ }
memcpy(buf, page_address(page) + offset, cpylen);
page_cache_release(page);
@@ -141,7 +161,10 @@
offset = 0;
index++;
}
- return 0;
+
+done:
+ read_unlock(&dev->bdev_mutex);
+ return err;
}
@@ -193,12 +216,22 @@
size_t *retlen, const u_char *buf)
{
struct block2mtd_dev *dev = mtd->priv;
- int err;
+ int err = 0;
+
+ read_lock(&dev->bdev_mutex);
+ if (!dev->blkdev) {
+ err = -EINVAL;
+ goto done;
+ }
if (!len)
- return 0;
- if (to >= mtd->size)
- return -ENOSPC;
+ goto done;
+
+ if (to >= mtd->size) {
+ err = -ENOSPC;
+ goto done;
+ }
+
if (to + len > mtd->size)
len = mtd->size - to;
@@ -207,6 +240,9 @@
mutex_unlock(&dev->write_mutex);
if (err > 0)
err = 0;
+
+done:
+ read_unlock(&dev->bdev_mutex);
return err;
}
@@ -215,51 +251,29 @@
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);
- close_bdev_excl(dev->blkdev);
- }
+ read_lock(&dev->bdev_mutex);
+ if (dev->blkdev)
+ sync_blockdev(dev->blkdev);
+ read_unlock(&dev->bdev_mutex);
- kfree(dev);
+ return;
}
-/* FIXME: ensure that mtd->size % erase_size == 0 */
-static struct block2mtd_dev *add_device(char *devname, int erase_size, char *mtdname)
+static int _open_bdev(struct block2mtd_dev *dev)
{
struct block_device *bdev;
- struct block2mtd_dev *dev;
- struct mtd_partition *part;
-
- if (!devname)
- return NULL;
-
- dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
- if (!dev)
- return NULL;
/* Get a handle on the device */
- bdev = open_bdev_excl(devname, O_RDWR, NULL);
+ bdev = open_bdev_excl(dev->devname, O_RDWR, NULL);
#ifndef MODULE
if (IS_ERR(bdev)) {
/* We might not have rootfs mounted at this point. Try
to resolve the device name by other means. */
- dev_t devt = name_to_dev_t(devname);
+ dev_t devt = name_to_dev_t(dev->devname);
if (devt) {
bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);
}
@@ -267,17 +281,96 @@
#endif
if (IS_ERR(bdev)) {
- ERROR("error: cannot open device %s", devname);
- goto devinit_err;
+ ERROR("error: cannot open device %s", dev->devname);
+ return 1;
}
dev->blkdev = bdev;
if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
ERROR("attempting to use an MTD device as a block device");
- goto devinit_err;
+ return 1;
}
+ return 0;
+}
+
+static void _close_bdev(struct block2mtd_dev *dev)
+{
+ struct block_device *bdev;
+
+ if (!dev->blkdev)
+ return;
+
+ bdev = dev->blkdev;
+ invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping, 0, -1);
+ close_bdev_excl(dev->blkdev);
+ dev->blkdev = NULL;
+}
+
+static void block2mtd_free_device(struct block2mtd_dev *dev)
+{
+ if (!dev)
+ return;
+
+ kfree(dev->mtd.name);
+ _close_bdev(dev);
+ kfree(dev);
+}
+
+
+static int block2mtd_refresh(struct mtd_info *mtd)
+{
+ struct block2mtd_dev *dev = mtd->priv;
+ struct block_device *bdev;
+ dev_t devt;
+ int err = 0;
+
+ /* no other mtd function can run at this point */
+ write_lock(&dev->bdev_mutex);
+
+ /* get the device number for the whole disk */
+ devt = MKDEV(MAJOR(dev->blkdev->bd_dev), 0);
+
+ /* close the old block device */
+ _close_bdev(dev);
+
+ /* open the whole disk, issue a partition rescan, then */
+ bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);
+ if (!bdev || !bdev->bd_disk)
+ err = -EINVAL;
+ else {
+ err = rescan_partitions(bdev->bd_disk, bdev);
+ }
+ if (bdev)
+ close_bdev_excl(bdev);
+
+ /* try to open the partition block device again */
+ _open_bdev(dev);
+ write_unlock(&dev->bdev_mutex);
+
+ return err;
+}
+
+/* FIXME: ensure that mtd->size % erase_size == 0 */
+static struct block2mtd_dev *add_device(char *devname, int erase_size, char *mtdname)
+{
+ struct block2mtd_dev *dev;
+ struct mtd_partition *part;
+
+ if (!devname)
+ return NULL;
+
+ dev = kzalloc(sizeof(struct block2mtd_dev) + strlen(devname) + 1, GFP_KERNEL);
+ if (!dev)
+ return NULL;
+
+ strcpy(dev->devname, devname);
+
+ if (_open_bdev(dev))
+ goto devinit_err;
+
mutex_init(&dev->write_mutex);
+ rwlock_init(&dev->bdev_mutex);
/* Setup the MTD structure */
/* make the name contain the block device in */
@@ -304,6 +397,7 @@
dev->mtd.read = block2mtd_read;
dev->mtd.priv = dev;
dev->mtd.owner = THIS_MODULE;
+ dev->mtd.refresh_device = block2mtd_refresh;
part = kzalloc(sizeof(struct mtd_partition), GFP_KERNEL);
part->name = dev->mtd.name;
Index: linux-2.6.22.1/drivers/mtd/mtdchar.c
===================================================================
--- linux-2.6.22.1.orig/drivers/mtd/mtdchar.c 2007-08-19 23:30:07.096116671 +0200
+++ linux-2.6.22.1/drivers/mtd/mtdchar.c 2007-08-19 23:31:44.041641284 +0200
@@ -16,6 +16,7 @@
#include <linux/mtd/mtd.h>
#include <linux/mtd/compatmac.h>
+#include <linux/mtd/partitions.h>
#include <asm/uaccess.h>
@@ -752,6 +753,13 @@
file->f_pos = 0;
break;
}
+#ifdef CONFIG_MTD_PARTITIONS
+ case MTDREFRESH:
+ {
+ ret = refresh_mtd_partitions(mtd);
+ break;
+ }
+#endif
default:
ret = -ENOTTY;
Index: linux-2.6.22.1/include/linux/mtd/mtd.h
===================================================================
--- linux-2.6.22.1.orig/include/linux/mtd/mtd.h 2007-08-19 23:30:07.100116893 +0200
+++ linux-2.6.22.1/include/linux/mtd/mtd.h 2007-08-19 23:31:44.105644933 +0200
@@ -98,6 +98,7 @@
uint8_t *oobbuf;
};
+struct mtd_info;
struct mtd_info {
u_char type;
u_int32_t flags;
@@ -195,6 +196,9 @@
struct module *owner;
int usecount;
+ int (*refresh_device)(struct mtd_info *mtd);
+ struct mtd_info *split;
+
/* If the driver is something smart, like UBI, it may need to maintain
* its own reference counting. The below functions are only for driver.
* The driver may register its callbacks. These callbacks are not
Index: linux-2.6.22.1/include/linux/mtd/partitions.h
===================================================================
--- linux-2.6.22.1.orig/include/linux/mtd/partitions.h 2007-08-19 23:30:07.112117591 +0200
+++ linux-2.6.22.1/include/linux/mtd/partitions.h 2007-08-19 23:31:44.133646528 +0200
@@ -36,6 +36,7 @@
* erasesize aligned (e.g. use MTDPART_OFS_NEXTBLK).
*/
+struct mtd_partition;
struct mtd_partition {
char *name; /* identifier string */
u_int32_t size; /* partition size */
@@ -43,6 +44,7 @@
u_int32_t mask_flags; /* master MTD flags to mask out for this partition */
struct nand_ecclayout *ecclayout; /* out of band layout for this partition (NAND only)*/
struct mtd_info **mtdp; /* pointer to store the MTD object */
+ int (*refresh_partition)(struct mtd_info *);
};
#define MTDPART_OFS_NXTBLK (-2)
@@ -52,6 +54,7 @@
int add_mtd_partitions(struct mtd_info *, const struct mtd_partition *, int);
int del_mtd_partitions(struct mtd_info *);
+int refresh_mtd_partitions(struct mtd_info *);
/*
* Functions dealing with the various ways of partitioning the space
Index: linux-2.6.22.1/include/mtd/mtd-abi.h
===================================================================
--- linux-2.6.22.1.orig/include/mtd/mtd-abi.h 2007-08-19 23:30:07.124118264 +0200
+++ linux-2.6.22.1/include/mtd/mtd-abi.h 2007-08-19 23:31:44.157647897 +0200
@@ -95,6 +95,7 @@
#define ECCGETLAYOUT _IOR('M', 17, struct nand_ecclayout)
#define ECCGETSTATS _IOR('M', 18, struct mtd_ecc_stats)
#define MTDFILEMODE _IO('M', 19)
+#define MTDREFRESH _IO('M', 23)
/*
* Obsolete legacy interface. Keep it in order not to break userspace