path: root/target/linux/generic-2.6/patches-2.6.23/065-rootfs_split.patch

Index: linux-2.6.23-rc6/drivers/mtd/Kconfig
===================================================================
--- linux-2.6.23-rc6.orig/drivers/mtd/Kconfig	2007-09-21 16:23:54.000000000 +0800
+++ linux-2.6.23-rc6/drivers/mtd/Kconfig	2007-09-21 16:23:59.000000000 +0800
@@ -47,6 +47,16 @@
 	  devices. Partitioning on NFTL 'devices' is a different - that's the
 	  'normal' form of partitioning used on a block device.
 
+config MTD_ROOTFS_ROOT_DEV
+	bool "Automatically set 'rootfs' partition to be root filesystem"
+	depends on MTD_PARTITIONS
+	default y
+
+config MTD_ROOTFS_SPLIT
+	bool "Automatically split 'rootfs' partition for squashfs"
+	depends on MTD_PARTITIONS
+	default y
+
 config MTD_REDBOOT_PARTS
 	tristate "RedBoot partition table parsing"
 	depends on MTD_PARTITIONS
Index: linux-2.6.23-rc6/drivers/mtd/mtdpart.c
===================================================================
--- linux-2.6.23-rc6.orig/drivers/mtd/mtdpart.c	2007-09-21 16:23:54.000000000 +0800
+++ linux-2.6.23-rc6/drivers/mtd/mtdpart.c	2007-09-21 16:23:59.000000000 +0800
@@ -20,6 +20,8 @@
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/partitions.h>
 #include <linux/mtd/compatmac.h>
+#include <linux/squashfs_fs.h>
+#include <linux/root_dev.h>
 
 /* Our partition linked list */
 static LIST_HEAD(mtd_partitions);
@@ -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;
 }
 
+static u_int32_t cur_offset = 0;
+static int add_one_partition(struct mtd_info *master, const struct mtd_partition *part,
+		int i, struct mtd_part **slp)
+{
+	struct mtd_part *slave;
+
+	/* allocate the partition structure */
+	slave = kzalloc (sizeof(*slave), GFP_KERNEL);
+	if (!slave) {
+		printk ("memory allocation error while creating partitions for \"%s\"\n",
+			master->name);
+		del_mtd_partitions(master);
+		return -ENOMEM;
+	}
+	list_add(&slave->list, &mtd_partitions);
+
+	/* set up the MTD object for this partition */
+	slave->mtd.type = master->type;
+	slave->mtd.flags = master->flags & ~part->mask_flags;
+	slave->mtd.size = part->size;
+	slave->mtd.writesize = master->writesize;
+	slave->mtd.oobsize = master->oobsize;
+	slave->mtd.oobavail = master->oobavail;
+	slave->mtd.subpage_sft = master->subpage_sft;
+
+	slave->mtd.name = part->name;
+	slave->mtd.owner = master->owner;
+
+	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;
+		slave->mtd.unpoint = part_unpoint;
+	}
+
+	if (master->read_oob)
+		slave->mtd.read_oob = part_read_oob;
+	if (master->write_oob)
+		slave->mtd.write_oob = part_write_oob;
+	if(master->read_user_prot_reg)
+		slave->mtd.read_user_prot_reg = part_read_user_prot_reg;
+	if(master->read_fact_prot_reg)
+		slave->mtd.read_fact_prot_reg = part_read_fact_prot_reg;
+	if(master->write_user_prot_reg)
+		slave->mtd.write_user_prot_reg = part_write_user_prot_reg;
+	if(master->lock_user_prot_reg)
+		slave->mtd.lock_user_prot_reg = part_lock_user_prot_reg;
+	if(master->get_user_prot_info)
+		slave->mtd.get_user_prot_info = part_get_user_prot_info;
+	if(master->get_fact_prot_info)
+		slave->mtd.get_fact_prot_info = part_get_fact_prot_info;
+	if (master->sync)
+		slave->mtd.sync = part_sync;
+	if (!i && master->suspend && master->resume) {
+			slave->mtd.suspend = part_suspend;
+			slave->mtd.resume = part_resume;
+	}
+	if (master->writev)
+		slave->mtd.writev = part_writev;
+	if (master->lock)
+		slave->mtd.lock = part_lock;
+	if (master->unlock)
+		slave->mtd.unlock = part_unlock;
+	if (master->block_isbad)
+		slave->mtd.block_isbad = part_block_isbad;
+	if (master->block_markbad)
+		slave->mtd.block_markbad = part_block_markbad;
+	slave->mtd.erase = part_erase;
+	slave->master = master;
+	slave->offset = part->offset;
+	slave->index = i;
+
+	if (slave->offset == MTDPART_OFS_APPEND)
+		slave->offset = cur_offset;
+	if (slave->offset == MTDPART_OFS_NXTBLK) {
+		slave->offset = cur_offset;
+		if ((cur_offset % master->erasesize) != 0) {
+			/* Round up to next erasesize */
+			slave->offset = ((cur_offset / master->erasesize) + 1) * master->erasesize;
+			printk(KERN_NOTICE "Moving partition %d: "
+			       "0x%08x -> 0x%08x\n", i,
+			       cur_offset, slave->offset);
+		}
+	}
+	if (slave->mtd.size == MTDPART_SIZ_FULL)
+		slave->mtd.size = master->size - slave->offset;
+	cur_offset = slave->offset + slave->mtd.size;
+
+	printk (KERN_NOTICE "0x%08x-0x%08x : \"%s\"\n", slave->offset,
+		slave->offset + slave->mtd.size, slave->mtd.name);
+
+	/* let's do some sanity checks */
+	if (slave->offset >= master->size) {
+			/* let's register it anyway to preserve ordering */
+		slave->offset = 0;
+		slave->mtd.size = 0;
+		printk ("mtd: partition \"%s\" is out of reach -- disabled\n",
+			part->name);
+	}
+	if (slave->offset + slave->mtd.size > master->size) {
+		slave->mtd.size = master->size - slave->offset;
+		printk ("mtd: partition \"%s\" extends beyond the end of device \"%s\" -- size truncated to %#x\n",
+			part->name, master->name, slave->mtd.size);
+	}
+	if (master->numeraseregions>1) {
+		/* Deal with variable erase size stuff */
+		int i;
+		struct mtd_erase_region_info *regions = master->eraseregions;
+
+		/* Find the first erase regions which is part of this partition. */
+		for (i=0; i < master->numeraseregions && slave->offset >= regions[i].offset; i++)
+			;
+
+		for (i--; i < master->numeraseregions && slave->offset + slave->mtd.size > regions[i].offset; i++) {
+			if (slave->mtd.erasesize < regions[i].erasesize) {
+				slave->mtd.erasesize = regions[i].erasesize;
+			}
+		}
+	} else {
+		/* Single erase size */
+		slave->mtd.erasesize = master->erasesize;
+	}
+
+	if ((slave->mtd.flags & MTD_WRITEABLE) &&
+	    (slave->offset % slave->mtd.erasesize)) {
+		/* Doesn't start on a boundary of major erase size */
+		/* FIXME: Let it be writable if it is on a boundary of _minor_ erase size though */
+		slave->mtd.flags &= ~MTD_WRITEABLE;
+		printk ("mtd: partition \"%s\" doesn't start on an erase block boundary -- force read-only\n",
+			part->name);
+	}
+	if ((slave->mtd.flags & MTD_WRITEABLE) &&
+	    (slave->mtd.size % slave->mtd.erasesize)) {
+		slave->mtd.flags &= ~MTD_WRITEABLE;
+		printk ("mtd: partition \"%s\" doesn't end on an erase block -- force read-only\n",
+			part->name);
+	}
+
+	slave->mtd.ecclayout = master->ecclayout;
+	if (master->block_isbad) {
+		uint32_t offs = 0;
+
+		while(offs < slave->mtd.size) {
+			if (master->block_isbad(master,
+						offs + slave->offset))
+				slave->mtd.ecc_stats.badblocks++;
+			offs += slave->mtd.erasesize;
+		}
+	}
+
+	if(part->mtdp)
+	{	/* store the object pointer (caller may or may not register it */
+		*part->mtdp = &slave->mtd;
+		slave->registered = 0;
+	}
+	else
+	{
+		/* register our partition */
+		add_mtd_device(&slave->mtd);
+		slave->registered = 1;
+	}
+
+	if (slp)
+		*slp = slave;
+
+	return 0;
+}
+
+#ifdef CONFIG_MTD_ROOTFS_SPLIT
+#define ROOTFS_SPLIT_NAME "rootfs_data"
+#define ROOTFS_REMOVED_NAME "<removed>"
+static int split_squashfs(struct mtd_info *master, int offset, int *split_offset)
+{
+	char buf[512];
+	struct squashfs_super_block *sb = (struct squashfs_super_block *) buf;
+	int len, 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);
+		return -EINVAL;
+	}
+
+	if (*((u32 *) buf) != SQUASHFS_MAGIC) {
+		printk(KERN_ALERT "split_squashfs: no squashfs found in \"%s\"\n",
+			master->name);
+		*split_offset = 0;
+		return 0;
+	}
+
+	if (sb->bytes_used <= 0) {
+		printk(KERN_ALERT "split_squashfs: squashfs is empty in \"%s\"\n",
+			master->name);
+		*split_offset = 0;
+		return 0;
+	}
+
+	len = (u32) sb->bytes_used;
+	len += (offset & 0x000fffff);
+	len +=  (master->erasesize - 1);
+	len &= ~(master->erasesize - 1);
+	len -= (offset & 0x000fffff);
+	*split_offset = offset + len;
+
+	return 0;
+}
+
+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->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, &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 +628,31 @@
 		       int nbparts)
 {
 	struct mtd_part *slave;
-	u_int32_t cur_offset = 0;
-	int i;
+	struct mtd_partition *part;
+	int i, j, ret = 0;
 
 	printk (KERN_NOTICE "Creating %d MTD partitions on \"%s\":\n", nbparts, master->name);
 
-	for (i = 0; i < nbparts; i++) {
-
-		/* allocate the partition structure */
-		slave = kzalloc (sizeof(*slave), GFP_KERNEL);
-		if (!slave) {
-			printk ("memory allocation error while creating partitions for \"%s\"\n",
-				master->name);
-			del_mtd_partitions(master);
-			return -ENOMEM;
-		}
-		list_add(&slave->list, &mtd_partitions);
-
-		/* set up the MTD object for this partition */
-		slave->mtd.type = master->type;
-		slave->mtd.flags = master->flags & ~parts[i].mask_flags;
-		slave->mtd.size = parts[i].size;
-		slave->mtd.writesize = master->writesize;
-		slave->mtd.oobsize = master->oobsize;
-		slave->mtd.oobavail = master->oobavail;
-		slave->mtd.subpage_sft = master->subpage_sft;
-
-		slave->mtd.name = parts[i].name;
-		slave->mtd.owner = master->owner;
-
-		slave->mtd.read = part_read;
-		slave->mtd.write = part_write;
-
-		if(master->point && master->unpoint){
-			slave->mtd.point = part_point;
-			slave->mtd.unpoint = part_unpoint;
-		}
-
-		if (master->read_oob)
-			slave->mtd.read_oob = part_read_oob;
-		if (master->write_oob)
-			slave->mtd.write_oob = part_write_oob;
-		if(master->read_user_prot_reg)
-			slave->mtd.read_user_prot_reg = part_read_user_prot_reg;
-		if(master->read_fact_prot_reg)
-			slave->mtd.read_fact_prot_reg = part_read_fact_prot_reg;
-		if(master->write_user_prot_reg)
-			slave->mtd.write_user_prot_reg = part_write_user_prot_reg;
-		if(master->lock_user_prot_reg)
-			slave->mtd.lock_user_prot_reg = part_lock_user_prot_reg;
-		if(master->get_user_prot_info)
-			slave->mtd.get_user_prot_info = part_get_user_prot_info;
-		if(master->get_fact_prot_info)
-			slave->mtd.get_fact_prot_info = part_get_fact_prot_info;
-		if (master->sync)
-			slave->mtd.sync = part_sync;
-		if (!i && master->suspend && master->resume) {
-				slave->mtd.suspend = part_suspend;
-				slave->mtd.resume = part_resume;
-		}
-		if (master->writev)
-			slave->mtd.writev = part_writev;
-		if (master->lock)
-			slave->mtd.lock = part_lock;
-		if (master->unlock)
-			slave->mtd.unlock = part_unlock;
-		if (master->block_isbad)
-			slave->mtd.block_isbad = part_block_isbad;
-		if (master->block_markbad)
-			slave->mtd.block_markbad = part_block_markbad;
-		slave->mtd.erase = part_erase;
-		slave->master = master;
-		slave->offset = parts[i].offset;
-		slave->index = i;
-
-		if (slave->offset == MTDPART_OFS_APPEND)
-			slave->offset = cur_offset;
-		if (slave->offset == MTDPART_OFS_NXTBLK) {
-			slave->offset = cur_offset;
-			if ((cur_offset % master->erasesize) != 0) {
-				/* Round up to next erasesize */
-				slave->offset = ((cur_offset / master->erasesize) + 1) * master->erasesize;
-				printk(KERN_NOTICE "Moving partition %d: "
-				       "0x%08x -> 0x%08x\n", i,
-				       cur_offset, slave->offset);
-			}
-		}
-		if (slave->mtd.size == MTDPART_SIZ_FULL)
-			slave->mtd.size = master->size - slave->offset;
-		cur_offset = slave->offset + slave->mtd.size;
-
-		printk (KERN_NOTICE "0x%08x-0x%08x : \"%s\"\n", slave->offset,
-			slave->offset + slave->mtd.size, slave->mtd.name);
-
-		/* let's do some sanity checks */
-		if (slave->offset >= master->size) {
-				/* let's register it anyway to preserve ordering */
-			slave->offset = 0;
-			slave->mtd.size = 0;
-			printk ("mtd: partition \"%s\" is out of reach -- disabled\n",
-				parts[i].name);
-		}
-		if (slave->offset + slave->mtd.size > master->size) {
-			slave->mtd.size = master->size - slave->offset;
-			printk ("mtd: partition \"%s\" extends beyond the end of device \"%s\" -- size truncated to %#x\n",
-				parts[i].name, master->name, slave->mtd.size);
-		}
-		if (master->numeraseregions>1) {
-			/* Deal with variable erase size stuff */
-			int i;
-			struct mtd_erase_region_info *regions = master->eraseregions;
-
-			/* Find the first erase regions which is part of this partition. */
-			for (i=0; i < master->numeraseregions && slave->offset >= regions[i].offset; i++)
-				;
-
-			for (i--; i < master->numeraseregions && slave->offset + slave->mtd.size > regions[i].offset; i++) {
-				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;
-		}
-
-		if ((slave->mtd.flags & MTD_WRITEABLE) &&
-		    (slave->offset % slave->mtd.erasesize)) {
-			/* Doesn't start on a boundary of major erase size */
-			/* FIXME: Let it be writable if it is on a boundary of _minor_ erase size though */
-			slave->mtd.flags &= ~MTD_WRITEABLE;
-			printk ("mtd: partition \"%s\" doesn't start on an erase block boundary -- force read-only\n",
-				parts[i].name);
-		}
-		if ((slave->mtd.flags & MTD_WRITEABLE) &&
-		    (slave->mtd.size % slave->mtd.erasesize)) {
-			slave->mtd.flags &= ~MTD_WRITEABLE;
-			printk ("mtd: partition \"%s\" doesn't end on an erase block -- force read-only\n",
-				parts[i].name);
-		}
-
-		slave->mtd.ecclayout = master->ecclayout;
-		if (master->block_isbad) {
-			uint32_t offs = 0;
-
-			while(offs < slave->mtd.size) {
-				if (master->block_isbad(master,
-							offs + slave->offset))
-					slave->mtd.ecc_stats.badblocks++;
-				offs += slave->mtd.erasesize;
-			}
-		}
-
-		if(parts[i].mtdp)
-		{	/* store the object pointer (caller may or may not register it */
-			*parts[i].mtdp = &slave->mtd;
-			slave->registered = 0;
-		}
-		else
-		{
-			/* register our partition */
-			add_mtd_device(&slave->mtd);
-			slave->registered = 1;
+#endif
+#ifdef CONFIG_MTD_ROOTFS_SPLIT
+			ret = split_rootfs_data(master, &slave->mtd, part, j);
+			if (ret == 0)
+				j++;
+#endif
 		}
 	}
 
@@ -557,6 +728,32 @@
 	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-2.6.23-rc6/drivers/mtd/devices/block2mtd.c
===================================================================
--- linux-2.6.23-rc6.orig/drivers/mtd/devices/block2mtd.c	2007-09-21 16:23:59.000000000 +0800
+++ linux-2.6.23-rc6/drivers/mtd/devices/block2mtd.c	2007-09-21 16:23:59.000000000 +0800
@@ -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-2.6.23-rc6/drivers/mtd/mtdchar.c
===================================================================
--- linux-2.6.23-rc6.orig/drivers/mtd/mtdchar.c	2007-09-21 16:23:54.000000000 +0800
+++ linux-2.6.23-rc6/drivers/mtd/mtdchar.c	2007-09-21 16:23:59.000000000 +0800
@@ -17,6 +17,7 @@
 
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/compatmac.h>
+#include <linux/mtd/partitions.h>
 
 #include <asm/uaccess.h>
 
@@ -753,6 +754,13 @@
 		file->f_pos = 0;
 		break;
 	}
+#ifdef CONFIG_MTD_PARTITIONS
+	case MTDREFRESH:
+	{
+		ret = refresh_mtd_partitions(mtd);
+		break;
+	}
+#endif
 
 	default:
 		ret = -ENOTTY;
Index: linux-2.6.23-rc6/include/linux/mtd/mtd.h
===================================================================
--- linux-2.6.23-rc6.orig/include/linux/mtd/mtd.h	2007-09-21 16:23:54.000000000 +0800
+++ linux-2.6.23-rc6/include/linux/mtd/mtd.h	2007-09-21 16:23:59.000000000 +0800
@@ -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-2.6.23-rc6/include/linux/mtd/partitions.h
===================================================================
--- linux-2.6.23-rc6.orig/include/linux/mtd/partitions.h	2007-09-21 16:23:54.000000000 +0800
+++ linux-2.6.23-rc6/include/linux/mtd/partitions.h	2007-09-21 16:23:59.000000000 +0800
@@ -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-2.6.23-rc6/include/mtd/mtd-abi.h
===================================================================
--- linux-2.6.23-rc6.orig/include/mtd/mtd-abi.h	2007-09-21 16:23:54.000000000 +0800
+++ linux-2.6.23-rc6/include/mtd/mtd-abi.h	2007-09-21 16:23:59.000000000 +0800
@@ -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