[PATCH] [UBI] 5/5 Simple FTL, take two
dmitry pervushin
dpervushin at gmail.com
Mon Dec 15 06:14:25 EST 2008
Simple mtdblock-like FTL over UBI volumes
Signed-off-by: dmitry pervushin <dimka at embeddedalley.com>
---
drivers/mtd/Kconfig | 8
drivers/mtd/Makefile | 1
drivers/mtd/ubiblock.c | 592 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 601 insertions(+)
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 at 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 at cam.org>
+ * (C) 1999-2003 David Woodhouse <dwmw2 at 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 at embeddedalley.com>");
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