Patchwork [UBI] 5/5 Simple FTL, take two

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Submitter dmitry pervushin
Date Dec. 15, 2008, 11:14 a.m.
Message ID <1229339665.7900.26.camel@hp.diimka.lan>
Download mbox | patch
Permalink /patch/14009/
State New, archived
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dmitry pervushin - Dec. 15, 2008, 11:14 a.m.
Simple mtdblock-like FTL over UBI volumes

Signed-off-by: dmitry pervushin <dimka@embeddedalley.com>

---
 drivers/mtd/Kconfig    |    8 
 drivers/mtd/Makefile   |    1 
 drivers/mtd/ubiblock.c |  592 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 601 insertions(+)

Patch

Index: ubifs-2.6/drivers/mtd/Kconfig
===================================================================
--- ubifs-2.6.orig/drivers/mtd/Kconfig
+++ ubifs-2.6/drivers/mtd/Kconfig
@@ -318,4 +318,12 @@  source "drivers/mtd/onenand/Kconfig"
 
 source "drivers/mtd/ubi/Kconfig"
 
+config MTD_UBI_BLOCK
+	tristate "Simple mtdblock-like FTL over UBI volumes"
+	depends on MTD_UBI
+	select MTD_BLKDEVS
+	default n
+	help
+	  This enables cached block access to UBI volumes
+
 endif # MTD
Index: ubifs-2.6/drivers/mtd/Makefile
===================================================================
--- ubifs-2.6.orig/drivers/mtd/Makefile
+++ ubifs-2.6/drivers/mtd/Makefile
@@ -32,3 +32,4 @@  inftl-objs		:= inftlcore.o inftlmount.o
 obj-y		+= chips/ maps/ devices/ nand/ onenand/
 
 obj-$(CONFIG_MTD_UBI)		+= ubi/
+obj-$(CONFIG_MTD_UBI_BLOCK)	+= ubiblock.o
Index: ubifs-2.6/drivers/mtd/ubiblock.c
===================================================================
--- /dev/null
+++ ubifs-2.6/drivers/mtd/ubiblock.c
@@ -0,0 +1,589 @@ 
+/*
+ * Direct UBI block device access
+ *
+ * Author: dmitry pervushin <dimka@embeddedalley.com>
+ *
+ * Copyright 2008 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2008 Embedded Alley Solutions, Inc. All Rights Reserved.
+ *
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * Based on mtdblock by:
+ * (C) 2000-2003 Nicolas Pitre <nico@cam.org>
+ * (C) 1999-2003 David Woodhouse <dwmw2@infradead.org>
+ */
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <linux/genhd.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/blktrans.h>
+#include <linux/mtd/ubi.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+
+#include "mtdcore.h"
+
+static LIST_HEAD(ubiblk_devices);
+
+/**
+ * ubiblk_dev - the structure representing translation layer
+ *
+ * @m: interface to mtd_blktrans
+ * @ubi_num: UBI device number
+ * @ubi_vol: UBI volume ID
+ * @usecount: reference count
+ *
+ * @cache_mutex: protects access to cache_data
+ * @cache_data: content of the cached LEB
+ * @cache_offset: offset of cached data on UBI volume, in bytes
+ * @cache_size: cache size in bytes, usually equal to LEB size
+ */
+struct ubiblk_dev {
+	struct mtd_blktrans_dev m;
+
+	int 			ubi_num;
+	int			ubi_vol;
+	int			usecount;
+	struct ubi_volume_desc *ubi;
+
+	struct mutex 		cache_mutex;
+	unsigned char 	       *cache_data;
+	unsigned long 		cache_offset;
+	unsigned int 		cache_size;
+
+	enum {
+		STATE_EMPTY,
+		STATE_CLEAN,
+		STATE_DIRTY
+	} cache_state;
+
+	struct list_head 	list;
+
+	struct work_struct	unbind;
+};
+
+static int ubiblock_open(struct mtd_blktrans_dev *mbd);
+static int ubiblock_release(struct mtd_blktrans_dev *mbd);
+static int ubiblock_flush(struct mtd_blktrans_dev *mbd);
+static int ubiblock_readsect(struct mtd_blktrans_dev *mbd,
+			      unsigned long block, char *buf);
+static int ubiblock_writesect(struct mtd_blktrans_dev *mbd,
+			      unsigned long block, char *buf);
+static int ubiblock_getgeo(struct mtd_blktrans_dev *mbd,
+		struct hd_geometry *geo);
+static void *ubiblk_add(int ubi_num, int ubi_vol_id);
+static void *ubiblk_add_locked(int ubi_num, int ubi_vol_id);
+static int ubiblk_del(struct ubiblk_dev *u);
+static int ubiblk_del_locked(struct ubiblk_dev *u);
+
+/*
+ * These two routines are just to satify mtd_blkdev's requirements
+ */
+static void ubiblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
+{
+	return;
+}
+
+static void ubiblock_remove_dev(struct mtd_blktrans_dev *mbd)
+{
+	return;
+}
+
+static struct mtd_blktrans_ops ubiblock_tr = {
+
+	.name		= "ubiblk",
+	.major		= 0,			/* assign dynamically  */
+	.part_bits	= 3,			/* allow up to 8 parts */
+	.blksize 	= 512,
+
+	.open		= ubiblock_open,
+	.release	= ubiblock_release,
+	.flush		= ubiblock_flush,
+	.readsect	= ubiblock_readsect,
+	.writesect	= ubiblock_writesect,
+	.getgeo		= ubiblock_getgeo,
+
+	.add_mtd	= ubiblock_add_mtd,
+	.remove_dev	= ubiblock_remove_dev,
+	.owner		= THIS_MODULE,
+};
+
+static int ubiblock_getgeo(struct mtd_blktrans_dev *bdev,
+		struct hd_geometry *geo)
+{
+	return -ENOTTY;
+}
+
+/**
+ * ubiblk_write_cached_data - flush the cache to the UBI volume
+ */
+static int ubiblk_write_cached_data(struct ubiblk_dev *u)
+{
+	int ret;
+
+	if (u->cache_state != STATE_DIRTY)
+		return 0;
+
+	pr_debug("%s: volume %d:%d, writing at %lx of size %x\n",
+		__func__, u->ubi_num, u->ubi_vol,
+		u->cache_offset, u->cache_size);
+
+	ret = ubi_write(u->ubi, u->cache_offset / u->cache_size,
+			u->cache_data, 0, u->cache_size);
+	pr_debug("leb_write status %d\n", ret);
+
+	u->cache_state = STATE_EMPTY;
+	return ret;
+}
+
+/**
+ * ubiblk_do_cached_write - cached write the data to the UBI volume
+ *
+ * @u: ubiblk_dev
+ * @pos: offset on the block device
+ * @len: buffer length
+ * @buf: buffer itself
+ *
+ * if buffer contains one or more whole sectors (=LEBs), write them to the
+ * volume. Otherwise, fill the cache that will be flushed later
+ */
+static int ubiblk_do_cached_write(struct ubiblk_dev *u, unsigned long pos,
+			    int len, const char *buf)
+{
+	unsigned int sect_size = u->cache_size,
+		size, offset;
+	unsigned long sect_start;
+	int ret = 0;
+	int leb;
+
+	pr_debug("%s: volume %d:%d, writing at pos %lx of size %x\n",
+		__func__, u->ubi_num, u->ubi_vol, pos, len);
+
+	while (len > 0) {
+		leb = pos / sect_size;
+		sect_start = leb * sect_size;
+		offset = pos - sect_start;
+		size = sect_size - offset;
+
+		if (size > len)
+			size = len;
+
+		if (size == sect_size) {
+			/*
+			 * We are covering a whole sector.  Thus there is no
+			 * need to bother with the cache while it may still be
+			 * useful for other partial writes.
+			 */
+			ret = ubi_leb_change(u->ubi, leb,
+					buf, size, UBI_UNKNOWN);
+			if (ret)
+				goto out;
+		} else {
+			/* Partial sector: need to use the cache */
+
+			if (u->cache_state == STATE_DIRTY &&
+			    u->cache_offset != sect_start) {
+				ret = ubiblk_write_cached_data(u);
+				if (ret)
+					goto out;
+			}
+
+			if (u->cache_state == STATE_EMPTY ||
+			    u->cache_offset != sect_start) {
+				/* fill the cache with the current sector */
+				u->cache_state = STATE_EMPTY;
+				ret = ubi_leb_read(u->ubi, leb,
+					u->cache_data, 0, u->cache_size, 0);
+				if (ret)
+					return ret;
+				ret = ubi_leb_unmap(u->ubi, leb);
+				if (ret)
+					return ret;
+				ret = ubi_leb_unmap(u->ubi, leb);
+				if (ret)
+					return ret;
+				u->cache_offset = sect_start;
+				u->cache_state = STATE_CLEAN;
+			}
+
+			/* write data to our local cache */
+			memcpy(u->cache_data + offset, buf, size);
+			u->cache_state = STATE_DIRTY;
+		}
+
+		buf += size;
+		pos += size;
+		len -= size;
+	}
+
+out:
+	return ret;
+}
+
+/**
+ * ubiblk_do_cached_read - cached read the data from ubi volume
+ *
+ * @u: ubiblk_dev
+ * @pos: offset on the block device
+ * @len: buffer length
+ * @buf: preallocated buffer
+ *
+ * Cached LEB will be used if possible; otherwise data will be using
+ * ubi_leb_read
+ */
+static int ubiblk_do_cached_read(struct ubiblk_dev *u, unsigned long pos,
+			   int len, char *buf)
+{
+	unsigned int sect_size = u->cache_size;
+	int err = 0;
+	unsigned long sect_start;
+	unsigned offset, size;
+	int leb;
+
+	pr_debug("%s: read at 0x%lx, size 0x%x\n",
+			__func__, pos, len);
+
+	while (len > 0) {
+
+		leb = pos/sect_size;
+		sect_start = leb*sect_size;
+		offset = pos - sect_start;
+		size = sect_size - offset;
+
+		if (size > len)
+			size = len;
+
+		/*
+		 * Check if the requested data is already cached
+		 * Read the requested amount of data from our internal
+		 * cache if it contains what we want, otherwise we read
+		 * the data directly from flash.
+		 */
+		if (u->cache_state != STATE_EMPTY &&
+		    u->cache_offset == sect_start) {
+			pr_debug("%s: cached, returning back from cache\n",
+					__func__);
+			memcpy(buf, u->cache_data + offset, size);
+			err = 0;
+		} else {
+			pr_debug("%s: pos = %ld, reading leb = %d\n",
+					__func__, pos, leb);
+			err = ubi_leb_read(u->ubi, leb, buf, offset, size, 0);
+			if (err)
+				goto out;
+		}
+
+		buf += size;
+		pos += size;
+		len -= size;
+	}
+
+out:
+	return err;
+}
+
+/**
+ * ubiblock_writesect - write the sector
+ *
+ * Allocate the cache, if necessary and perform actual write using
+ * ubiblk_do_cached_write
+ */
+static int ubiblock_writesect(struct mtd_blktrans_dev *mbd,
+			      unsigned long block, char *buf)
+{
+	struct ubiblk_dev *u = container_of(mbd, struct ubiblk_dev, m);
+
+	if (unlikely(!u->cache_data)) {
+		u->cache_data = vmalloc(u->cache_size);
+		if (!u->cache_data)
+			return -EAGAIN;
+	}
+	return ubiblk_do_cached_write(u, block<<9, 512, buf);
+}
+
+/**
+ * ubiblk_readsect - read the sector
+ *
+ * Allocate the cache, if necessary, and perform actual read using
+ * ubiblk_do_cached_read
+ */
+static int ubiblock_readsect(struct mtd_blktrans_dev *mbd,
+			      unsigned long block, char *buf)
+{
+	struct ubiblk_dev *u = container_of(mbd, struct ubiblk_dev, m);
+
+	if (unlikely(!u->cache_data)) {
+		u->cache_data = vmalloc(u->cache_size);
+		if (!u->cache_data)
+			return -EAGAIN;
+	}
+	return ubiblk_do_cached_read(u, block<<9, 512, buf);
+}
+
+static int ubiblk_flush_locked(struct ubiblk_dev *u)
+{
+	ubiblk_write_cached_data(u);
+	ubi_sync(u->ubi_num);
+	return 0;
+}
+
+static int ubiblock_flush(struct mtd_blktrans_dev *mbd)
+{
+	struct ubiblk_dev *u = container_of(mbd, struct ubiblk_dev, m);
+
+	mutex_lock(&u->cache_mutex);
+	ubiblk_flush_locked(u);
+	mutex_unlock(&u->cache_mutex);
+	return 0;
+}
+
+
+static int ubiblock_open(struct mtd_blktrans_dev *mbd)
+{
+	struct ubiblk_dev *u = container_of(mbd, struct ubiblk_dev, m);
+
+	if (u->usecount == 0) {
+		u->ubi = ubi_open_volume(u->ubi_num, u->ubi_vol,
+				UBI_READWRITE);
+		if (IS_ERR(u->ubi))
+			return PTR_ERR(u->ubi);
+	}
+	u->usecount++;
+	return 0;
+}
+
+static int ubiblock_release(struct mtd_blktrans_dev *mbd)
+{
+	struct ubiblk_dev *u = container_of(mbd, struct ubiblk_dev, m);
+
+	if (--u->usecount == 0) {
+		mutex_lock(&u->cache_mutex);
+		ubiblk_flush_locked(u);
+		vfree(u->cache_data);
+		u->cache_data = NULL;
+		mutex_unlock(&u->cache_mutex);
+		ubi_close_volume(u->ubi);
+		u->ubi = NULL;
+	}
+	return 0;
+}
+
+/*
+ * sysfs routines. The ubiblk creates two entries under /sys/block/ubiblkX:
+ *  - volume, R/O, which is read like "ubi0:volume_name"
+ *  - unbind, W/O; when user writes something here, the block device is
+ *  removed
+ *
+ *  unbind schedules a work item to perform real unbind, because sysfs entry
+ *  handler cannot delete itself :)
+ */
+ssize_t volume_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct gendisk *gd = dev_to_disk(dev);
+	struct mtd_blktrans_dev *m = gd->private_data;
+	struct ubiblk_dev *u = container_of(m, struct ubiblk_dev, m);
+
+	return sprintf(buf, "%d:%d\n", u->ubi_num, u->ubi_vol);
+}
+
+static void ubiblk_unbind(struct work_struct *ws)
+{
+	struct ubiblk_dev *u = container_of(ws, struct ubiblk_dev, unbind);
+
+	ubiblk_del(u);
+}
+
+ssize_t unbind_store(struct device *dev, struct device_attribute *attr,
+			 const char *buf, size_t count)
+{
+	struct gendisk *gd = dev_to_disk(dev);
+	struct mtd_blktrans_dev *m = gd->private_data;
+	struct ubiblk_dev *u = container_of(m, struct ubiblk_dev, m);
+
+	INIT_WORK(&u->unbind, ubiblk_unbind);
+	schedule_work(&u->unbind);
+	return count;
+}
+
+DEVICE_ATTR(unbind, 0644, NULL, unbind_store);
+DEVICE_ATTR(volume, 0644, volume_show, NULL);
+
+static int ubiblk_sysfs(struct gendisk *hd, int add)
+{
+	int r = 0;
+
+	if (add) {
+		r = device_create_file(disk_to_dev(hd), &dev_attr_unbind);
+		if (r < 0)
+			goto out;
+		r = device_create_file(disk_to_dev(hd), &dev_attr_volume);
+		if (r < 0)
+			goto out1;
+		return 0;
+	}
+
+	device_remove_file(disk_to_dev(hd), &dev_attr_unbind);
+out1:
+	device_remove_file(disk_to_dev(hd), &dev_attr_volume);
+out:
+	return r;
+}
+
+
+/**
+ * add the FTL by registering it with mtd_blkdevs
+ */
+static void *ubiblk_add(int ubi_num, int ubi_vol_id)
+{
+	void *p;
+
+	mutex_lock(&mtd_table_mutex);
+	p = ubiblk_add_locked(ubi_num, ubi_vol_id);
+	mutex_unlock(&mtd_table_mutex);
+	return p;
+}
+
+static void *ubiblk_add_locked(int ubi_num, int ubi_vol_id)
+{
+	struct ubiblk_dev *u = kzalloc(sizeof(*u), GFP_KERNEL);
+	struct ubi_volume_info uvi;
+	struct ubi_volume_desc *ubi;
+
+	if (!u) {
+		u = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	ubi = ubi_open_volume(ubi_num, ubi_vol_id, UBI_READONLY);
+	if (IS_ERR(u->ubi)) {
+		pr_err("cannot open the volume\n");
+		u = (void *)u->ubi;
+		goto out;
+	}
+
+	ubi_get_volume_info(ubi, &uvi);
+	ubi_close_volume(ubi);
+
+	pr_debug("adding volume of size %d (used_size %lld), LEB size %d\n",
+		uvi.size, uvi.used_bytes, uvi.usable_leb_size);
+
+	u->m.mtd = NULL;
+	u->m.devnum = -1;
+	u->m.size = uvi.used_bytes >> 9;
+	u->m.tr = &ubiblock_tr;
+
+	u->ubi_num = ubi_num;
+	u->ubi_vol = ubi_vol_id;
+
+	mutex_init(&u->cache_mutex);
+	u->cache_state = STATE_EMPTY;
+	u->cache_size = uvi.usable_leb_size;
+	u->cache_data = NULL;
+	u->usecount = 0;
+	INIT_LIST_HEAD(&u->list);
+
+	list_add_tail(&u->list, &ubiblk_devices);
+	add_mtd_blktrans_dev(&u->m);
+	ubiblk_sysfs(u->m.blkcore_priv, true);
+out:
+	return u;
+}
+
+static int ubiblk_del(struct ubiblk_dev *u)
+{
+	int r;
+	mutex_lock(&mtd_table_mutex);
+	r = ubiblk_del_locked(u);
+	mutex_unlock(&mtd_table_mutex);
+	return r;
+}
+
+static int ubiblk_del_locked(struct ubiblk_dev *u)
+{
+	if (u->usecount != 0)
+		return -EBUSY;
+	ubiblk_sysfs(u->m.blkcore_priv, false);
+	del_mtd_blktrans_dev(&u->m);
+	list_del(&u->list);
+	BUG_ON(u->cache_data != NULL); /* who did not free the cache ?! */
+	kfree(u);
+	return 0;
+}
+
+static struct ubiblk_dev *ubiblk_find(int num, int vol)
+{
+	struct ubiblk_dev *pos;
+
+	list_for_each_entry(pos, &ubiblk_devices, list)
+		if (pos->ubi_num == num && pos->ubi_vol == vol)
+			return pos;
+	return NULL;
+}
+
+static int ubiblock_notification(struct notifier_block *blk,
+		unsigned long type, void *v)
+{
+	struct ubi_volume_notification *nt = v;
+	struct ubiblk_dev *u;
+
+	switch ((enum ubi_volume_notification_type)type) {
+	case UBI_VOLUME_ADDED:
+		ubiblk_add(nt->ubi_num, nt->vol_id);
+		break;
+	case UBI_VOLUME_DELETED:
+		u = ubiblk_find(nt->ubi_num, nt->vol_id);
+		if (u)
+			ubiblk_del(u);
+		break;
+	case UBI_VOLUME_RENAMED:
+	case UBI_VOLUME_CHANGED:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block ubiblock_nb = {
+	.notifier_call = ubiblock_notification,
+};
+
+static int __init ubiblock_init(void)
+{
+	int r;
+
+	r = register_mtd_blktrans(&ubiblock_tr);
+	if (r)
+		goto out;
+	r = ubi_register_volume_notifier(&ubiblock_nb, 0);
+	if (r)
+		goto out_unreg;
+	return 0;
+
+out_unreg:
+	deregister_mtd_blktrans(&ubiblock_tr);
+out:
+	return 0;
+}
+
+static void __exit ubiblock_exit(void)
+{
+	ubi_unregister_volume_notifier(&ubiblock_nb);
+	deregister_mtd_blktrans(&ubiblock_tr);
+}
+
+module_init(ubiblock_init);
+module_exit(ubiblock_exit);
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Caching block device emulation access to UBI devices");
+MODULE_AUTHOR("dmitry pervushin <dimka@embeddedalley.com>");