1 files changed, 490 insertions, 184 deletions

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 0236539..6ac81e3 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -21,11 +21,16 @@
  */
 
 /*
- * This file includes UBI initialization and building of UBI devices. At the
- * moment UBI devices may only be added while UBI is initialized, but dynamic
- * device add/remove functionality is planned. Also, at the moment we only
- * attach UBI devices by scanning, which will become a bottleneck when flashes
- * reach certain large size. Then one may improve UBI and add other methods.
+ * This file includes UBI initialization and building of UBI devices.
+ *
+ * When UBI is initialized, it attaches all the MTD devices specified as the
+ * module load parameters or the kernel boot parameters. If MTD devices were
+ * specified, UBI does not attach any MTD device, but it is possible to do
+ * later using the "UBI control device".
+ *
+ * At the moment we only attach UBI devices by scanning, which will become a
+ * bottleneck when flashes reach certain large size. Then one may improve UBI
+ * and add other methods, although it does not seem to be easy to do.
  */
 
 #include <linux/err.h>
@@ -33,7 +38,9 @@
 #include <linux/moduleparam.h>
 #include <linux/stringify.h>
 #include <linux/stat.h>
+#include <linux/miscdevice.h>
 #include <linux/log2.h>
+#include <linux/kthread.h>
 #include "ubi.h"
 
 /* Maximum length of the 'mtd=' parameter */
@@ -43,13 +50,11 @@
  * struct mtd_dev_param - MTD device parameter description data structure.
  * @name: MTD device name or number string
  * @vid_hdr_offs: VID header offset
- * @data_offs: data offset
  */
 struct mtd_dev_param
 {
 	char name[MTD_PARAM_LEN_MAX];
 	int vid_hdr_offs;
-	int data_offs;
 };
 
 /* Numbers of elements set in the @mtd_dev_param array */
@@ -58,14 +63,27 @@ static int mtd_devs = 0;
 /* MTD devices specification parameters */
 static struct mtd_dev_param mtd_dev_param[UBI_MAX_DEVICES];
 
-/* Number of UBI devices in system */
-int ubi_devices_cnt;
+/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
+struct class *ubi_class;
+
+/* Slab cache for wear-leveling entries */
+struct kmem_cache *ubi_wl_entry_slab;
+
+/* UBI control character device */
+static struct miscdevice ubi_ctrl_cdev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "ubi_ctrl",
+	.fops = &ubi_ctrl_cdev_operations,
+};
 
 /* All UBI devices in system */
-struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
+static struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
 
-/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
-struct class *ubi_class;
+/* Serializes UBI devices creations and removals */
+DEFINE_MUTEX(ubi_devices_mutex);
+
+/* Protects @ubi_devices and @ubi->ref_count */
+static DEFINE_SPINLOCK(ubi_devices_lock);
 
 /* "Show" method for files in '/<sysfs>/class/ubi/' */
 static ssize_t ubi_version_show(struct class *class, char *buf)
@@ -101,38 +119,150 @@ static struct device_attribute dev_min_io_size =
 	__ATTR(min_io_size, S_IRUGO, dev_attribute_show, NULL);
 static struct device_attribute dev_bgt_enabled =
 	__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_mtd_num =
+	__ATTR(mtd_num, S_IRUGO, dev_attribute_show, NULL);
+
+/**
+ * ubi_get_device - get UBI device.
+ * @ubi_num: UBI device number
+ *
+ * This function returns UBI device description object for UBI device number
+ * @ubi_num, or %NULL if the device does not exist. This function increases the
+ * device reference count to prevent removal of the device. In other words, the
+ * device cannot be removed if its reference count is not zero.
+ */
+struct ubi_device *ubi_get_device(int ubi_num)
+{
+	struct ubi_device *ubi;
+
+	spin_lock(&ubi_devices_lock);
+	ubi = ubi_devices[ubi_num];
+	if (ubi) {
+		ubi_assert(ubi->ref_count >= 0);
+		ubi->ref_count += 1;
+		get_device(&ubi->dev);
+	}
+	spin_unlock(&ubi_devices_lock);
+
+	return ubi;
+}
+
+/**
+ * ubi_put_device - drop an UBI device reference.
+ * @ubi: UBI device description object
+ */
+void ubi_put_device(struct ubi_device *ubi)
+{
+	spin_lock(&ubi_devices_lock);
+	ubi->ref_count -= 1;
+	put_device(&ubi->dev);
+	spin_unlock(&ubi_devices_lock);
+}
+
+/**
+ * ubi_get_by_major - get UBI device description object by character device
+ *                    major number.
+ * @major: major number
+ *
+ * This function is similar to 'ubi_get_device()', but it searches the device
+ * by its major number.
+ */
+struct ubi_device *ubi_get_by_major(int major)
+{
+	int i;
+	struct ubi_device *ubi;
+
+	spin_lock(&ubi_devices_lock);
+	for (i = 0; i < UBI_MAX_DEVICES; i++) {
+		ubi = ubi_devices[i];
+		if (ubi && MAJOR(ubi->cdev.dev) == major) {
+			ubi_assert(ubi->ref_count >= 0);
+			ubi->ref_count += 1;
+			get_device(&ubi->dev);
+			spin_unlock(&ubi_devices_lock);
+			return ubi;
+		}
+	}
+	spin_unlock(&ubi_devices_lock);
+
+	return NULL;
+}
+
+/**
+ * ubi_major2num - get UBI device number by character device major number.
+ * @major: major number
+ *
+ * This function searches UBI device number object by its major number. If UBI
+ * device was not found, this function returns -ENODEV, otherwise the UBI device
+ * number is returned.
+ */
+int ubi_major2num(int major)
+{
+	int i, ubi_num = -ENODEV;
+
+	spin_lock(&ubi_devices_lock);
+	for (i = 0; i < UBI_MAX_DEVICES; i++) {
+		struct ubi_device *ubi = ubi_devices[i];
+
+		if (ubi && MAJOR(ubi->cdev.dev) == major) {
+			ubi_num = ubi->ubi_num;
+			break;
+		}
+	}
+	spin_unlock(&ubi_devices_lock);
+
+	return ubi_num;
+}
 
 /* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
 static ssize_t dev_attribute_show(struct device *dev,
 				  struct device_attribute *attr, char *buf)
 {
-	const struct ubi_device *ubi;
+	ssize_t ret;
+	struct ubi_device *ubi;
 
+	/*
+	 * The below code looks weird, but it actually makes sense. We get the
+	 * UBI device reference from the contained 'struct ubi_device'. But it
+	 * is unclear if the device was removed or not yet. Indeed, if the
+	 * device was removed before we increased its reference count,
+	 * 'ubi_get_device()' will return -ENODEV and we fail.
+	 *
+	 * Remember, 'struct ubi_device' is freed in the release function, so
+	 * we still can use 'ubi->ubi_num'.
+	 */
 	ubi = container_of(dev, struct ubi_device, dev);
+	ubi = ubi_get_device(ubi->ubi_num);
+	if (!ubi)
+		return -ENODEV;
+
 	if (attr == &dev_eraseblock_size)
-		return sprintf(buf, "%d\n", ubi->leb_size);
+		ret = sprintf(buf, "%d\n", ubi->leb_size);
 	else if (attr == &dev_avail_eraseblocks)
-		return sprintf(buf, "%d\n", ubi->avail_pebs);
+		ret = sprintf(buf, "%d\n", ubi->avail_pebs);
 	else if (attr == &dev_total_eraseblocks)
-		return sprintf(buf, "%d\n", ubi->good_peb_count);
+		ret = sprintf(buf, "%d\n", ubi->good_peb_count);
 	else if (attr == &dev_volumes_count)
-		return sprintf(buf, "%d\n", ubi->vol_count);
+		ret = sprintf(buf, "%d\n", ubi->vol_count - UBI_INT_VOL_COUNT);
 	else if (attr == &dev_max_ec)
-		return sprintf(buf, "%d\n", ubi->max_ec);
+		ret = sprintf(buf, "%d\n", ubi->max_ec);
 	else if (attr == &dev_reserved_for_bad)
-		return sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
+		ret = sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
 	else if (attr == &dev_bad_peb_count)
-		return sprintf(buf, "%d\n", ubi->bad_peb_count);
+		ret = sprintf(buf, "%d\n", ubi->bad_peb_count);
 	else if (attr == &dev_max_vol_count)
-		return sprintf(buf, "%d\n", ubi->vtbl_slots);
+		ret = sprintf(buf, "%d\n", ubi->vtbl_slots);
 	else if (attr == &dev_min_io_size)
-		return sprintf(buf, "%d\n", ubi->min_io_size);
+		ret = sprintf(buf, "%d\n", ubi->min_io_size);
 	else if (attr == &dev_bgt_enabled)
-		return sprintf(buf, "%d\n", ubi->thread_enabled);
+		ret = sprintf(buf, "%d\n", ubi->thread_enabled);
+	else if (attr == &dev_mtd_num)
+		ret = sprintf(buf, "%d\n", ubi->mtd->index);
 	else
-		BUG();
+		ret = -EINVAL;
 
-	return 0;
+	ubi_put_device(ubi);
+	return ret;
 }
 
 /* Fake "release" method for UBI devices */
@@ -150,68 +280,44 @@ static int ubi_sysfs_init(struct ubi_device *ubi)
 	int err;
 
 	ubi->dev.release = dev_release;
-	ubi->dev.devt = MKDEV(ubi->major, 0);
+	ubi->dev.devt = ubi->cdev.dev;
 	ubi->dev.class = ubi_class;
 	sprintf(&ubi->dev.bus_id[0], UBI_NAME_STR"%d", ubi->ubi_num);
 	err = device_register(&ubi->dev);
 	if (err)
-		goto out;
+		return err;
 
 	err = device_create_file(&ubi->dev, &dev_eraseblock_size);
 	if (err)
-		goto out_unregister;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_avail_eraseblocks);
 	if (err)
-		goto out_eraseblock_size;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_total_eraseblocks);
 	if (err)
-		goto out_avail_eraseblocks;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_volumes_count);
 	if (err)
-		goto out_total_eraseblocks;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_max_ec);
 	if (err)
-		goto out_volumes_count;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_reserved_for_bad);
 	if (err)
-		goto out_volumes_max_ec;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_bad_peb_count);
 	if (err)
-		goto out_reserved_for_bad;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_max_vol_count);
 	if (err)
-		goto out_bad_peb_count;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_min_io_size);
 	if (err)
-		goto out_max_vol_count;
+		return err;
 	err = device_create_file(&ubi->dev, &dev_bgt_enabled);
 	if (err)
-		goto out_min_io_size;
-
-	return 0;
-
-out_min_io_size:
-	device_remove_file(&ubi->dev, &dev_min_io_size);
-out_max_vol_count:
-	device_remove_file(&ubi->dev, &dev_max_vol_count);
-out_bad_peb_count:
-	device_remove_file(&ubi->dev, &dev_bad_peb_count);
-out_reserved_for_bad:
-	device_remove_file(&ubi->dev, &dev_reserved_for_bad);
-out_volumes_max_ec:
-	device_remove_file(&ubi->dev, &dev_max_ec);
-out_volumes_count:
-	device_remove_file(&ubi->dev, &dev_volumes_count);
-out_total_eraseblocks:
-	device_remove_file(&ubi->dev, &dev_total_eraseblocks);
-out_avail_eraseblocks:
-	device_remove_file(&ubi->dev, &dev_avail_eraseblocks);
-out_eraseblock_size:
-	device_remove_file(&ubi->dev, &dev_eraseblock_size);
-out_unregister:
-	device_unregister(&ubi->dev);
-out:
-	ubi_err("failed to initialize sysfs for %s", ubi->ubi_name);
+		return err;
+	err = device_create_file(&ubi->dev, &dev_mtd_num);
 	return err;
 }
 
@@ -221,6 +327,7 @@ out:
  */
 static void ubi_sysfs_close(struct ubi_device *ubi)
 {
+	device_remove_file(&ubi->dev, &dev_mtd_num);
 	device_remove_file(&ubi->dev, &dev_bgt_enabled);
 	device_remove_file(&ubi->dev, &dev_min_io_size);
 	device_remove_file(&ubi->dev, &dev_max_vol_count);
@@ -244,7 +351,7 @@ static void kill_volumes(struct ubi_device *ubi)
 
 	for (i = 0; i < ubi->vtbl_slots; i++)
 		if (ubi->volumes[i])
-			ubi_free_volume(ubi, i);
+			ubi_free_volume(ubi, ubi->volumes[i]);
 }
 
 /**
@@ -259,9 +366,6 @@ static int uif_init(struct ubi_device *ubi)
 	int i, err;
 	dev_t dev;
 
-	mutex_init(&ubi->vtbl_mutex);
-	spin_lock_init(&ubi->volumes_lock);
-
 	sprintf(ubi->ubi_name, UBI_NAME_STR "%d", ubi->ubi_num);
 
 	/*
@@ -278,39 +382,40 @@ static int uif_init(struct ubi_device *ubi)
 		return err;
 	}
 
+	ubi_assert(MINOR(dev) == 0);
 	cdev_init(&ubi->cdev, &ubi_cdev_operations);
-	ubi->major = MAJOR(dev);
-	dbg_msg("%s major is %u", ubi->ubi_name, ubi->major);
+	dbg_msg("%s major is %u", ubi->ubi_name, MAJOR(dev));
 	ubi->cdev.owner = THIS_MODULE;
 
-	dev = MKDEV(ubi->major, 0);
 	err = cdev_add(&ubi->cdev, dev, 1);
 	if (err) {
-		ubi_err("cannot add character device %s", ubi->ubi_name);
+		ubi_err("cannot add character device");
 		goto out_unreg;
 	}
 
 	err = ubi_sysfs_init(ubi);
 	if (err)
-		goto out_cdev;
+		goto out_sysfs;
 
 	for (i = 0; i < ubi->vtbl_slots; i++)
 		if (ubi->volumes[i]) {
-			err = ubi_add_volume(ubi, i);
-			if (err)
+			err = ubi_add_volume(ubi, ubi->volumes[i]);
+			if (err) {
+				ubi_err("cannot add volume %d", i);
 				goto out_volumes;
+			}
 		}
 
 	return 0;
 
 out_volumes:
 	kill_volumes(ubi);
+out_sysfs:
 	ubi_sysfs_close(ubi);
-out_cdev:
 	cdev_del(&ubi->cdev);
 out_unreg:
-	unregister_chrdev_region(MKDEV(ubi->major, 0),
-				 ubi->vtbl_slots + 1);
+	unregister_chrdev_region(ubi->cdev.dev, ubi->vtbl_slots + 1);
+	ubi_err("cannot initialize UBI %s, error %d", ubi->ubi_name, err);
 	return err;
 }
 
@@ -323,7 +428,7 @@ static void uif_close(struct ubi_device *ubi)
 	kill_volumes(ubi);
 	ubi_sysfs_close(ubi);
 	cdev_del(&ubi->cdev);
-	unregister_chrdev_region(MKDEV(ubi->major, 0), ubi->vtbl_slots + 1);
+	unregister_chrdev_region(ubi->cdev.dev, ubi->vtbl_slots + 1);
 }
 
 /**
@@ -384,9 +489,9 @@ out_si:
  * assumed:
  *   o EC header is always at offset zero - this cannot be changed;
  *   o VID header starts just after the EC header at the closest address
- *   aligned to @io->@hdrs_min_io_size;
+ *     aligned to @io->hdrs_min_io_size;
  *   o data starts just after the VID header at the closest address aligned to
- *     @io->@min_io_size
+ *     @io->min_io_size
  *
  * This function returns zero in case of success and a negative error code in
  * case of failure.
@@ -407,6 +512,9 @@ static int io_init(struct ubi_device *ubi)
 		return -EINVAL;
 	}
 
+	if (ubi->vid_hdr_offset < 0)
+		return -EINVAL;
+
 	/*
 	 * Note, in this implementation we support MTD devices with 0x7FFFFFFF
 	 * physical eraseblocks maximum.
@@ -424,7 +532,8 @@ static int io_init(struct ubi_device *ubi)
 
 	/* Make sure minimal I/O unit is power of 2 */
 	if (!is_power_of_2(ubi->min_io_size)) {
-		ubi_err("bad min. I/O unit");
+		ubi_err("min. I/O unit (%d) is not power of 2",
+			ubi->min_io_size);
 		return -EINVAL;
 	}
 
@@ -453,10 +562,8 @@ static int io_init(struct ubi_device *ubi)
 	}
 
 	/* Similar for the data offset */
-	if (ubi->leb_start == 0) {
-		ubi->leb_start = ubi->vid_hdr_offset + ubi->vid_hdr_alsize;
-		ubi->leb_start = ALIGN(ubi->leb_start, ubi->min_io_size);
-	}
+	ubi->leb_start = ubi->vid_hdr_offset + UBI_EC_HDR_SIZE;
+	ubi->leb_start = ALIGN(ubi->leb_start, ubi->min_io_size);
 
 	dbg_msg("vid_hdr_offset   %d", ubi->vid_hdr_offset);
 	dbg_msg("vid_hdr_aloffset %d", ubi->vid_hdr_aloffset);
@@ -514,76 +621,147 @@ static int io_init(struct ubi_device *ubi)
 }
 
 /**
- * attach_mtd_dev - attach an MTD device.
- * @mtd_dev: MTD device name or number string
- * @vid_hdr_offset: VID header offset
- * @data_offset: data offset
+ * autoresize - re-size the volume which has the "auto-resize" flag set.
+ * @ubi: UBI device description object
+ * @vol_id: ID of the volume to re-size
  *
- * This function attaches an MTD device to UBI. It first treats @mtd_dev as the
- * MTD device name, and tries to open it by this name. If it is unable to open,
- * it tries to convert @mtd_dev to an integer and open the MTD device by its
- * number. Returns zero in case of success and a negative error code in case of
- * failure.
+ * This function re-sizes the volume marked by the @UBI_VTBL_AUTORESIZE_FLG in
+ * the volume table to the largest possible size. See comments in ubi-header.h
+ * for more description of the flag. Returns zero in case of success and a
+ * negative error code in case of failure.
  */
-static int attach_mtd_dev(const char *mtd_dev, int vid_hdr_offset,
-			  int data_offset)
+static int autoresize(struct ubi_device *ubi, int vol_id)
 {
-	struct ubi_device *ubi;
-	struct mtd_info *mtd;
-	int i, err;
+	struct ubi_volume_desc desc;
+	struct ubi_volume *vol = ubi->volumes[vol_id];
+	int err, old_reserved_pebs = vol->reserved_pebs;
 
-	mtd = get_mtd_device_nm(mtd_dev);
-	if (IS_ERR(mtd)) {
-		int mtd_num;
-		char *endp;
+	/*
+	 * Clear the auto-resize flag in the volume in-memory copy of the
+	 * volume table, and 'ubi_resize_volume()' will propogate this change
+	 * to the flash.
+	 */
+	ubi->vtbl[vol_id].flags &= ~UBI_VTBL_AUTORESIZE_FLG;
 
-		if (PTR_ERR(mtd) != -ENODEV)
-			return PTR_ERR(mtd);
+	if (ubi->avail_pebs == 0) {
+		struct ubi_vtbl_record vtbl_rec;
 
 		/*
-		 * Probably this is not MTD device name but MTD device number -
-		 * check this out.
+		 * No avalilable PEBs to re-size the volume, clear the flag on
+		 * flash and exit.
 		 */
-		mtd_num = simple_strtoul(mtd_dev, &endp, 0);
-		if (*endp != '\0' || mtd_dev == endp) {
-			ubi_err("incorrect MTD device: \"%s\"", mtd_dev);
-			return -ENODEV;
-		}
-
-		mtd = get_mtd_device(NULL, mtd_num);
-		if (IS_ERR(mtd))
-			return PTR_ERR(mtd);
+		memcpy(&vtbl_rec, &ubi->vtbl[vol_id],
+		       sizeof(struct ubi_vtbl_record));
+		err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
+		if (err)
+			ubi_err("cannot clean auto-resize flag for volume %d",
+				vol_id);
+	} else {
+		desc.vol = vol;
+		err = ubi_resize_volume(&desc,
+					old_reserved_pebs + ubi->avail_pebs);
+		if (err)
+			ubi_err("cannot auto-resize volume %d", vol_id);
 	}
 
-	/* Check if we already have the same MTD device attached */
-	for (i = 0; i < ubi_devices_cnt; i++)
-		if (ubi_devices[i]->mtd->index == mtd->index) {
-			ubi_err("mtd%d is already attached to ubi%d",
+	if (err)
+		return err;
+
+	ubi_msg("volume %d (\"%s\") re-sized from %d to %d LEBs", vol_id,
+		vol->name, old_reserved_pebs, vol->reserved_pebs);
+	return 0;
+}
+
+/**
+ * ubi_attach_mtd_dev - attach an MTD device.
+ * @mtd_dev: MTD device description object
+ * @ubi_num: number to assign to the new UBI device
+ * @vid_hdr_offset: VID header offset
+ *
+ * This function attaches MTD device @mtd_dev to UBI and assign @ubi_num number
+ * to the newly created UBI device, unless @ubi_num is %UBI_DEV_NUM_AUTO, in
+ * which case this function finds a vacant device nubert and assings it
+ * automatically. Returns the new UBI device number in case of success and a
+ * negative error code in case of failure.
+ *
+ * Note, the invocations of this function has to be serialized by the
+ * @ubi_devices_mutex.
+ */
+int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
+{
+	struct ubi_device *ubi;
+	int i, err;
+
+	/*
+	 * Check if we already have the same MTD device attached.
+	 *
+	 * Note, this function assumes that UBI devices creations and deletions
+	 * are serialized, so it does not take the &ubi_devices_lock.
+	 */
+	for (i = 0; i < UBI_MAX_DEVICES; i++) {
+		ubi = ubi_devices[i];
+		if (ubi && mtd->index == ubi->mtd->index) {
+			dbg_err("mtd%d is already attached to ubi%d",
 				mtd->index, i);
-			err = -EINVAL;
-			goto out_mtd;
+			return -EEXIST;
 		}
+	}
 
-	ubi = ubi_devices[ubi_devices_cnt] = kzalloc(sizeof(struct ubi_device),
-						     GFP_KERNEL);
-	if (!ubi) {
-		err = -ENOMEM;
-		goto out_mtd;
+	/*
+	 * Make sure this MTD device is not emulated on top of an UBI volume
+	 * already. Well, generally this recursion works fine, but there are
+	 * different problems like the UBI module takes a reference to itself
+	 * by attaching (and thus, opening) the emulated MTD device. This
+	 * results in inability to unload the module. And in general it makes
+	 * no sense to attach emulated MTD devices, so we prohibit this.
+	 */
+	if (mtd->type == MTD_UBIVOLUME) {
+		ubi_err("refuse attaching mtd%d - it is already emulated on "
+			"top of UBI", mtd->index);
+		return -EINVAL;
 	}
 
-	ubi->ubi_num = ubi_devices_cnt;
-	ubi->mtd = mtd;
+	if (ubi_num == UBI_DEV_NUM_AUTO) {
+		/* Search for an empty slot in the @ubi_devices array */
+		for (ubi_num = 0; ubi_num < UBI_MAX_DEVICES; ubi_num++)
+			if (!ubi_devices[ubi_num])
+				break;
+		if (ubi_num == UBI_MAX_DEVICES) {
+			dbg_err("only %d UBI devices may be created", UBI_MAX_DEVICES);
+			return -ENFILE;
+		}
+	} else {
+		if (ubi_num >= UBI_MAX_DEVICES)
+			return -EINVAL;
+
+		/* Make sure ubi_num is not busy */
+		if (ubi_devices[ubi_num]) {
+			dbg_err("ubi%d already exists", ubi_num);
+			return -EEXIST;
+		}
+	}
 
-	dbg_msg("attaching mtd%d to ubi%d: VID header offset %d data offset %d",
-		ubi->mtd->index, ubi_devices_cnt, vid_hdr_offset, data_offset);
+	ubi = kzalloc(sizeof(struct ubi_device), GFP_KERNEL);
+	if (!ubi)
+		return -ENOMEM;
 
+	ubi->mtd = mtd;
+	ubi->ubi_num = ubi_num;
 	ubi->vid_hdr_offset = vid_hdr_offset;
-	ubi->leb_start = data_offset;
+	ubi->autoresize_vol_id = -1;
+
+	mutex_init(&ubi->buf_mutex);
+	mutex_init(&ubi->ckvol_mutex);
+	mutex_init(&ubi->volumes_mutex);
+	spin_lock_init(&ubi->volumes_lock);
+
+	dbg_msg("attaching mtd%d to ubi%d: VID header offset %d",
+		mtd->index, ubi_num, vid_hdr_offset);
+
 	err = io_init(ubi);
 	if (err)
 		goto out_free;
 
-	mutex_init(&ubi->buf_mutex);
 	ubi->peb_buf1 = vmalloc(ubi->peb_size);
 	if (!ubi->peb_buf1)
 		goto out_free;
@@ -605,12 +783,26 @@ static int attach_mtd_dev(const char *mtd_dev, int vid_hdr_offset,
 		goto out_free;
 	}
 
+	if (ubi->autoresize_vol_id != -1) {
+		err = autoresize(ubi, ubi->autoresize_vol_id);
+		if (err)
+			goto out_detach;
+	}
+
 	err = uif_init(ubi);
 	if (err)
 		goto out_detach;
 
-	ubi_msg("attached mtd%d to ubi%d", ubi->mtd->index, ubi_devices_cnt);
-	ubi_msg("MTD device name:            \"%s\"", ubi->mtd->name);
+	ubi->bgt_thread = kthread_create(ubi_thread, ubi, ubi->bgt_name);
+	if (IS_ERR(ubi->bgt_thread)) {
+		err = PTR_ERR(ubi->bgt_thread);
+		ubi_err("cannot spawn \"%s\", error %d", ubi->bgt_name,
+			err);
+		goto out_uif;
+	}
+
+	ubi_msg("attached mtd%d to ubi%d", mtd->index, ubi_num);
+	ubi_msg("MTD device name:            \"%s\"", mtd->name);
 	ubi_msg("MTD device size:            %llu MiB", ubi->flash_size >> 20);
 	ubi_msg("physical eraseblock size:   %d bytes (%d KiB)",
 		ubi->peb_size, ubi->peb_size >> 10);
@@ -638,9 +830,11 @@ static int attach_mtd_dev(const char *mtd_dev, int vid_hdr_offset,
 		wake_up_process(ubi->bgt_thread);
 	}
 
-	ubi_devices_cnt += 1;
-	return 0;
+	ubi_devices[ubi_num] = ubi;
+	return ubi_num;
 
+out_uif:
+	uif_close(ubi);
 out_detach:
 	ubi_eba_close(ubi);
 	ubi_wl_close(ubi);
@@ -652,21 +846,58 @@ out_free:
 	vfree(ubi->dbg_peb_buf);
 #endif
 	kfree(ubi);
-out_mtd:
-	put_mtd_device(mtd);
-	ubi_devices[ubi_devices_cnt] = NULL;
 	return err;
 }
 
 /**
- * detach_mtd_dev - detach an MTD device.
- * @ubi: UBI device description object
+ * ubi_detach_mtd_dev - detach an MTD device.
+ * @ubi_num: UBI device number to detach from
+ * @anyway: detach MTD even if device reference count is not zero
+ *
+ * This function destroys an UBI device number @ubi_num and detaches the
+ * underlying MTD device. Returns zero in case of success and %-EBUSY if the
+ * UBI device is busy and cannot be destroyed, and %-EINVAL if it does not
+ * exist.
+ *
+ * Note, the invocations of this function has to be serialized by the
+ * @ubi_devices_mutex.
  */
-static void detach_mtd_dev(struct ubi_device *ubi)
+int ubi_detach_mtd_dev(int ubi_num, int anyway)
 {
-	int ubi_num = ubi->ubi_num, mtd_num = ubi->mtd->index;
+	struct ubi_device *ubi;
+
+	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
+		return -EINVAL;
+
+	spin_lock(&ubi_devices_lock);
+	ubi = ubi_devices[ubi_num];
+	if (!ubi) {
+		spin_unlock(&ubi_devices_lock);
+		return -EINVAL;
+	}
+
+	if (ubi->ref_count) {
+		if (!anyway) {
+			spin_unlock(&ubi_devices_lock);
+			return -EBUSY;
+		}
+		/* This may only happen if there is a bug */
+		ubi_err("%s reference count %d, destroy anyway",
+			ubi->ubi_name, ubi->ref_count);
+	}
+	ubi_devices[ubi_num] = NULL;
+	spin_unlock(&ubi_devices_lock);
 
+	ubi_assert(ubi_num == ubi->ubi_num);
 	dbg_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi_num);
+
+	/*
+	 * Before freeing anything, we have to stop the background thread to
+	 * prevent it from doing anything on this device while we are freeing.
+	 */
+	if (ubi->bgt_thread)
+		kthread_stop(ubi->bgt_thread);
+
 	uif_close(ubi);
 	ubi_eba_close(ubi);
 	ubi_wl_close(ubi);
@@ -677,11 +908,37 @@ static void detach_mtd_dev(struct ubi_device *ubi)
 #ifdef CONFIG_MTD_UBI_DEBUG
 	vfree(ubi->dbg_peb_buf);
 #endif
-	kfree(ubi_devices[ubi_num]);
-	ubi_devices[ubi_num] = NULL;
-	ubi_devices_cnt -= 1;
-	ubi_assert(ubi_devices_cnt >= 0);
-	ubi_msg("mtd%d is detached from ubi%d", mtd_num, ubi_num);
+	ubi_msg("mtd%d is detached from ubi%d", ubi->mtd->index, ubi->ubi_num);
+	kfree(ubi);
+	return 0;
+}
+
+/**
+ * find_mtd_device - open an MTD device by its name or number.
+ * @mtd_dev: name or number of the device
+ *
+ * This function tries to open and MTD device described by @mtd_dev string,
+ * which is first treated as an ASCII number, and if it is not true, it is
+ * treated as MTD device name. Returns MTD device description object in case of
+ * success and a negative error code in case of failure.
+ */
+static struct mtd_info * __init open_mtd_device(const char *mtd_dev)
+{
+	struct mtd_info *mtd;
+	int mtd_num;
+	char *endp;
+
+	mtd_num = simple_strtoul(mtd_dev, &endp, 0);
+	if (*endp != '\0' || mtd_dev == endp) {
+		/*
+		 * This does not look like an ASCII integer, probably this is
+		 * MTD device name.
+		 */
+		mtd = get_mtd_device_nm(mtd_dev);
+	} else
+		mtd = get_mtd_device(NULL, mtd_num);
+
+	return mtd;
 }
 
 static int __init ubi_init(void)
@@ -693,47 +950,96 @@ static int __init ubi_init(void)
 	BUILD_BUG_ON(sizeof(struct ubi_vid_hdr) != 64);
 
 	if (mtd_devs > UBI_MAX_DEVICES) {
-		printk("UBI error: too many MTD devices, maximum is %d\n",
-		       UBI_MAX_DEVICES);
+		printk(KERN_ERR "UBI error: too many MTD devices, "
+		       "maximum is %d\n", UBI_MAX_DEVICES);
 		return -EINVAL;
 	}
 
+	/* Create base sysfs directory and sysfs files */
 	ubi_class = class_create(THIS_MODULE, UBI_NAME_STR);
-	if (IS_ERR(ubi_class))
-		return PTR_ERR(ubi_class);
+	if (IS_ERR(ubi_class)) {
+		err = PTR_ERR(ubi_class);
+		printk(KERN_ERR "UBI error: cannot create UBI class\n");
+		goto out;
+	}
 
 	err = class_create_file(ubi_class, &ubi_version);
-	if (err)
+	if (err) {
+		printk(KERN_ERR "UBI error: cannot create sysfs file\n");
 		goto out_class;
+	}
+
+	err = misc_register(&ubi_ctrl_cdev);
+	if (err) {
+		printk(KERN_ERR "UBI error: cannot register device\n");
+		goto out_version;
+	}
+
+	ubi_wl_entry_slab = kmem_cache_create("ubi_wl_entry_slab",
+						sizeof(struct ubi_wl_entry),
+						0, 0, NULL);
+	if (!ubi_wl_entry_slab)
+		goto out_dev_unreg;
 
 	/* Attach MTD devices */
 	for (i = 0; i < mtd_devs; i++) {
 		struct mtd_dev_param *p = &mtd_dev_param[i];
+		struct mtd_info *mtd;
 
 		cond_resched();
-		err = attach_mtd_dev(p->name, p->vid_hdr_offs, p->data_offs);
-		if (err)
+
+		mtd = open_mtd_device(p->name);
+		if (IS_ERR(mtd)) {
+			err = PTR_ERR(mtd);
+			goto out_detach;
+		}
+
+		mutex_lock(&ubi_devices_mutex);
+		err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO,
+					 p->vid_hdr_offs);
+		mutex_unlock(&ubi_devices_mutex);
+		if (err < 0) {
+			put_mtd_device(mtd);
+			printk(KERN_ERR "UBI error: cannot attach %s\n",
+			       p->name);
 			goto out_detach;
+		}
 	}
 
 	return 0;
 
 out_detach:
 	for (k = 0; k < i; k++)
-		detach_mtd_dev(ubi_devices[k]);
+		if (ubi_devices[k]) {
+			mutex_lock(&ubi_devices_mutex);
+			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
+			mutex_unlock(&ubi_devices_mutex);
+		}
+	kmem_cache_destroy(ubi_wl_entry_slab);
+out_dev_unreg:
+	misc_deregister(&ubi_ctrl_cdev);
+out_version:
 	class_remove_file(ubi_class, &ubi_version);
 out_class:
 	class_destroy(ubi_class);
+out:
+	printk(KERN_ERR "UBI error: cannot initialize UBI, error %d\n", err);
 	return err;
 }
 module_init(ubi_init);
 
 static void __exit ubi_exit(void)
 {
-	int i, n = ubi_devices_cnt;
+	int i;
 
-	for (i = 0; i < n; i++)
-		detach_mtd_dev(ubi_devices[i]);
+	for (i = 0; i < UBI_MAX_DEVICES; i++)
+		if (ubi_devices[i]) {
+			mutex_lock(&ubi_devices_mutex);
+			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
+			mutex_unlock(&ubi_devices_mutex);
+		}
+	kmem_cache_destroy(ubi_wl_entry_slab);
+	misc_deregister(&ubi_ctrl_cdev);
 	class_remove_file(ubi_class, &ubi_version);
 	class_destroy(ubi_class);
 }
@@ -754,7 +1060,8 @@ static int __init bytes_str_to_int(const char *str)
 
 	result = simple_strtoul(str, &endp, 0);
 	if (str == endp || result < 0) {
-		printk("UBI error: incorrect bytes count: \"%s\"\n", str);
+		printk(KERN_ERR "UBI error: incorrect bytes count: \"%s\"\n",
+		       str);
 		return -EINVAL;
 	}
 
@@ -764,15 +1071,14 @@ static int __init bytes_str_to_int(const char *str)
 	case 'M':
 		result *= 1024;
 	case 'K':
-	case 'k':
 		result *= 1024;
-		if (endp[1] == 'i' && (endp[2] == '\0' ||
-			  endp[2] == 'B'  || endp[2] == 'b'))
+		if (endp[1] == 'i' && endp[2] == 'B')
 			endp += 2;
 	case '\0':
 		break;
 	default:
-		printk("UBI error: incorrect bytes count: \"%s\"\n", str);
+		printk(KERN_ERR "UBI error: incorrect bytes count: \"%s\"\n",
+		       str);
 		return -EINVAL;
 	}
 
@@ -793,23 +1099,27 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
 	struct mtd_dev_param *p;
 	char buf[MTD_PARAM_LEN_MAX];
 	char *pbuf = &buf[0];
-	char *tokens[3] = {NULL, NULL, NULL};
+	char *tokens[2] = {NULL, NULL};
+
+	if (!val)
+		return -EINVAL;
 
 	if (mtd_devs == UBI_MAX_DEVICES) {
-		printk("UBI error: too many parameters, max. is %d\n",
+		printk(KERN_ERR "UBI error: too many parameters, max. is %d\n",
 		       UBI_MAX_DEVICES);
 		return -EINVAL;
 	}
 
 	len = strnlen(val, MTD_PARAM_LEN_MAX);
 	if (len == MTD_PARAM_LEN_MAX) {
-		printk("UBI error: parameter \"%s\" is too long, max. is %d\n",
-		       val, MTD_PARAM_LEN_MAX);
+		printk(KERN_ERR "UBI error: parameter \"%s\" is too long, "
+		       "max. is %d\n", val, MTD_PARAM_LEN_MAX);
 		return -EINVAL;
 	}
 
 	if (len == 0) {
-		printk("UBI warning: empty 'mtd=' parameter - ignored\n");
+		printk(KERN_WARNING "UBI warning: empty 'mtd=' parameter - "
+		       "ignored\n");
 		return 0;
 	}
 
@@ -819,11 +1129,12 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
 	if (buf[len - 1] == '\n')
 		buf[len - 1] = '\0';
 
-	for (i = 0; i < 3; i++)
+	for (i = 0; i < 2; i++)
 		tokens[i] = strsep(&pbuf, ",");
 
 	if (pbuf) {
-		printk("UBI error: too many arguments at \"%s\"\n", val);
+		printk(KERN_ERR "UBI error: too many arguments at \"%s\"\n",
+		       val);
 		return -EINVAL;
 	}
 
@@ -832,13 +1143,9 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
 
 	if (tokens[1])
 		p->vid_hdr_offs = bytes_str_to_int(tokens[1]);
-	if (tokens[2])
-		p->data_offs = bytes_str_to_int(tokens[2]);
 
 	if (p->vid_hdr_offs < 0)
 		return p->vid_hdr_offs;
-	if (p->data_offs < 0)
-		return p->data_offs;
 
 	mtd_devs += 1;
 	return 0;
@@ -846,16 +1153,15 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
 
 module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
 MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: "
-		      "mtd=<name|num>[,<vid_hdr_offs>,<data_offs>]. "
+		      "mtd=<name|num>[,<vid_hdr_offs>].\n"
 		      "Multiple \"mtd\" parameters may be specified.\n"
-		      "MTD devices may be specified by their number or name. "
-		      "Optional \"vid_hdr_offs\" and \"data_offs\" parameters "
-		      "specify UBI VID header position and data starting "
-		      "position to be used by UBI.\n"
-		      "Example: mtd=content,1984,2048 mtd=4 - attach MTD device"
-		      "with name content using VID header offset 1984 and data "
-		      "start 2048, and MTD device number 4 using default "
-		      "offsets");
+		      "MTD devices may be specified by their number or name.\n"
+		      "Optional \"vid_hdr_offs\" parameter specifies UBI VID "
+		      "header position and data starting position to be used "
+		      "by UBI.\n"
+		      "Example: mtd=content,1984 mtd=4 - attach MTD device"
+		      "with name \"content\" using VID header offset 1984, and "
+		      "MTD device number 4 with default VID header offset.");
 
 MODULE_VERSION(__stringify(UBI_VERSION));
 MODULE_DESCRIPTION("UBI - Unsorted Block Images");