--- /dev/null
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
+ */
+
+/*
+ * This is a small driver which implements fake MTD devices on top of UBI
+ * volumes. This sounds strange, but it is in fact quite useful to make
+ * MTD-oriented software (including all the legacy software) work on top of
+ * UBI.
+ *
+ * Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
+ * size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The
+ * eraseblock size is equivalent to the logical eraseblock size of the volume.
+ */
+
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/mtd/ubi.h>
+#include <linux/mtd/mtd.h>
+#include "ubi-media.h"
+
+#define err_msg(fmt, ...) \
+ pr_err("gluebi (pid %d): %s: " fmt "\n", \
+ current->pid, __func__, ##__VA_ARGS__)
+
+/**
+ * struct gluebi_device - a gluebi device description data structure.
+ * @mtd: emulated MTD device description object
+ * @refcnt: gluebi device reference count
+ * @desc: UBI volume descriptor
+ * @ubi_num: UBI device number this gluebi device works on
+ * @vol_id: ID of UBI volume this gluebi device works on
+ * @list: link in a list of gluebi devices
+ */
+struct gluebi_device {
+ struct mtd_info mtd;
+ int refcnt;
+ struct ubi_volume_desc *desc;
+ int ubi_num;
+ int vol_id;
+ struct list_head list;
+};
+
+/* List of all gluebi devices */
+static LIST_HEAD(gluebi_devices);
+static DEFINE_MUTEX(devices_mutex);
+
+/**
+ * find_gluebi_nolock - find a gluebi device.
+ * @ubi_num: UBI device number
+ * @vol_id: volume ID
+ *
+ * This function seraches for gluebi device corresponding to UBI device
+ * @ubi_num and UBI volume @vol_id. Returns the gluebi device description
+ * object in case of success and %NULL in case of failure. The caller has to
+ * have the &devices_mutex locked.
+ */
+static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id)
+{
+ struct gluebi_device *gluebi;
+
+ list_for_each_entry(gluebi, &gluebi_devices, list)
+ if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id)
+ return gluebi;
+ return NULL;
+}
+
+/**
+ * gluebi_get_device - get MTD device reference.
+ * @mtd: the MTD device description object
+ *
+ * This function is called every time the MTD device is being opened and
+ * implements the MTD get_device() operation. Returns zero in case of success
+ * and a negative error code in case of failure.
+ */
+static int gluebi_get_device(struct mtd_info *mtd)
+{
+ struct gluebi_device *gluebi;
+ int ubi_mode = UBI_READONLY;
+
+ if (!try_module_get(THIS_MODULE))
+ return -ENODEV;
+
+ if (mtd->flags & MTD_WRITEABLE)
+ ubi_mode = UBI_READWRITE;
+
+ gluebi = container_of(mtd, struct gluebi_device, mtd);
+ mutex_lock(&devices_mutex);
+ if (gluebi->refcnt > 0) {
+ /*
+ * The MTD device is already referenced and this is just one
+ * more reference. MTD allows many users to open the same
+ * volume simultaneously and do not distinguish between
+ * readers/writers/exclusive openers as UBI does. So we do not
+ * open the UBI volume again - just increase the reference
+ * counter and return.
+ */
+ gluebi->refcnt += 1;
+ mutex_unlock(&devices_mutex);
+ return 0;
+ }
+
+ /*
+ * This is the first reference to this UBI volume via the MTD device
+ * interface. Open the corresponding volume in read-write mode.
+ */
+ gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id,
+ ubi_mode);
+ if (IS_ERR(gluebi->desc)) {
+ mutex_unlock(&devices_mutex);
+ module_put(THIS_MODULE);
+ return PTR_ERR(gluebi->desc);
+ }
+ gluebi->refcnt += 1;
+ mutex_unlock(&devices_mutex);
+ return 0;
+}
+
+/**
+ * gluebi_put_device - put MTD device reference.
+ * @mtd: the MTD device description object
+ *
+ * This function is called every time the MTD device is being put. Returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+static void gluebi_put_device(struct mtd_info *mtd)
+{
+ struct gluebi_device *gluebi;
+
+ gluebi = container_of(mtd, struct gluebi_device, mtd);
+ mutex_lock(&devices_mutex);
+ gluebi->refcnt -= 1;
+ if (gluebi->refcnt == 0)
+ ubi_close_volume(gluebi->desc);
+ module_put(THIS_MODULE);
+ mutex_unlock(&devices_mutex);
+}
+
+/**
+ * gluebi_read - read operation of emulated MTD devices.
+ * @mtd: MTD device description object
+ * @from: absolute offset from where to read
+ * @len: how many bytes to read
+ * @retlen: count of read bytes is returned here
+ * @buf: buffer to store the read data
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
+ size_t *retlen, unsigned char *buf)
+{
+ int err = 0, lnum, offs, bytes_left;
+ struct gluebi_device *gluebi;
+
+ gluebi = container_of(mtd, struct gluebi_device, mtd);
+ lnum = div_u64_rem(from, mtd->erasesize, &offs);
+ bytes_left = len;
+ while (bytes_left) {
+ size_t to_read = mtd->erasesize - offs;
+
+ if (to_read > bytes_left)
+ to_read = bytes_left;
+
+ err = ubi_read(gluebi->desc, lnum, buf, offs, to_read);
+ if (err)
+ break;
+
+ lnum += 1;
+ offs = 0;
+ bytes_left -= to_read;
+ buf += to_read;
+ }
+
+ *retlen = len - bytes_left;
+ return err;
+}
+
+/**
+ * gluebi_write - write operation of emulated MTD devices.
+ * @mtd: MTD device description object
+ * @to: absolute offset where to write
+ * @len: how many bytes to write
+ * @retlen: count of written bytes is returned here
+ * @buf: buffer with data to write
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
+ size_t *retlen, const u_char *buf)
+{
+ int err = 0, lnum, offs, bytes_left;
+ struct gluebi_device *gluebi;
+
+ gluebi = container_of(mtd, struct gluebi_device, mtd);
+ lnum = div_u64_rem(to, mtd->erasesize, &offs);
+
+ if (len % mtd->writesize || offs % mtd->writesize)
+ return -EINVAL;
+
+ bytes_left = len;
+ while (bytes_left) {
+ size_t to_write = mtd->erasesize - offs;
+
+ if (to_write > bytes_left)
+ to_write = bytes_left;
+
+ err = ubi_leb_write(gluebi->desc, lnum, buf, offs, to_write);
+ if (err)
+ break;
+
+ lnum += 1;
+ offs = 0;
+ bytes_left -= to_write;
+ buf += to_write;
+ }
+
+ *retlen = len - bytes_left;
+ return err;
+}
+
+/**
+ * gluebi_erase - erase operation of emulated MTD devices.
+ * @mtd: the MTD device description object
+ * @instr: the erase operation description
+ *
+ * This function calls the erase callback when finishes. Returns zero in case
+ * of success and a negative error code in case of failure.
+ */
+static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
+{
+ int err, i, lnum, count;
+ struct gluebi_device *gluebi;
+
+ if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd))
+ return -EINVAL;
+
+ lnum = mtd_div_by_eb(instr->addr, mtd);
+ count = mtd_div_by_eb(instr->len, mtd);
+ gluebi = container_of(mtd, struct gluebi_device, mtd);
+
+ for (i = 0; i < count - 1; i++) {
+ err = ubi_leb_unmap(gluebi->desc, lnum + i);
+ if (err)
+ goto out_err;
+ }
+ /*
+ * MTD erase operations are synchronous, so we have to make sure the
+ * physical eraseblock is wiped out.
+ *
+ * Thus, perform leb_erase instead of leb_unmap operation - leb_erase
+ * will wait for the end of operations
+ */
+ err = ubi_leb_erase(gluebi->desc, lnum + i);
+ if (err)
+ goto out_err;
+
+ instr->state = MTD_ERASE_DONE;
+ mtd_erase_callback(instr);
+ return 0;
+
+out_err:
+ instr->state = MTD_ERASE_FAILED;
+ instr->fail_addr = (long long)lnum * mtd->erasesize;
+ return err;
+}
+
+/**
+ * gluebi_create - create a gluebi device for an UBI volume.
+ * @di: UBI device description object
+ * @vi: UBI volume description object
+ *
+ * This function is called when a new UBI volume is created in order to create
+ * corresponding fake MTD device. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int gluebi_create(struct ubi_device_info *di,
+ struct ubi_volume_info *vi)
+{
+ struct gluebi_device *gluebi, *g;
+ struct mtd_info *mtd;
+
+ gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL);
+ if (!gluebi)
+ return -ENOMEM;
+
+ mtd = &gluebi->mtd;
+ mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL);
+ if (!mtd->name) {
+ kfree(gluebi);
+ return -ENOMEM;
+ }
+
+ gluebi->vol_id = vi->vol_id;
+ gluebi->ubi_num = vi->ubi_num;
+ mtd->type = MTD_UBIVOLUME;
+ if (!di->ro_mode)
+ mtd->flags = MTD_WRITEABLE;
+ mtd->owner = THIS_MODULE;
+ mtd->writesize = di->min_io_size;
+ mtd->erasesize = vi->usable_leb_size;
+ mtd->_read = gluebi_read;
+ mtd->_write = gluebi_write;
+ mtd->_erase = gluebi_erase;
+ mtd->_get_device = gluebi_get_device;
+ mtd->_put_device = gluebi_put_device;
+
+ /*
+ * In case of dynamic a volume, MTD device size is just volume size. In
+ * case of a static volume the size is equivalent to the amount of data
+ * bytes.
+ */
+ if (vi->vol_type == UBI_DYNAMIC_VOLUME)
+ mtd->size = (unsigned long long)vi->usable_leb_size * vi->size;
+ else
+ mtd->size = vi->used_bytes;
+
+ /* Just a sanity check - make sure this gluebi device does not exist */
+ mutex_lock(&devices_mutex);
+ g = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+ if (g)
+ err_msg("gluebi MTD device %d form UBI device %d volume %d already exists",
+ g->mtd.index, vi->ubi_num, vi->vol_id);
+ mutex_unlock(&devices_mutex);
+
+ if (mtd_device_register(mtd, NULL, 0)) {
+ err_msg("cannot add MTD device");
+ kfree(mtd->name);
+ kfree(gluebi);
+ return -ENFILE;
+ }
+
+ mutex_lock(&devices_mutex);
+ list_add_tail(&gluebi->list, &gluebi_devices);
+ mutex_unlock(&devices_mutex);
+ return 0;
+}
+
+/**
+ * gluebi_remove - remove a gluebi device.
+ * @vi: UBI volume description object
+ *
+ * This function is called when an UBI volume is removed and it removes
+ * corresponding fake MTD device. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int gluebi_remove(struct ubi_volume_info *vi)
+{
+ int err = 0;
+ struct mtd_info *mtd;
+ struct gluebi_device *gluebi;
+
+ mutex_lock(&devices_mutex);
+ gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+ if (!gluebi) {
+ err_msg("got remove notification for unknown UBI device %d volume %d",
+ vi->ubi_num, vi->vol_id);
+ err = -ENOENT;
+ } else if (gluebi->refcnt)
+ err = -EBUSY;
+ else
+ list_del(&gluebi->list);
+ mutex_unlock(&devices_mutex);
+ if (err)
+ return err;
+
+ mtd = &gluebi->mtd;
+ err = mtd_device_unregister(mtd);
+ if (err) {
+ err_msg("cannot remove fake MTD device %d, UBI device %d, volume %d, error %d",
+ mtd->index, gluebi->ubi_num, gluebi->vol_id, err);
+ mutex_lock(&devices_mutex);
+ list_add_tail(&gluebi->list, &gluebi_devices);
+ mutex_unlock(&devices_mutex);
+ return err;
+ }
+
+ kfree(mtd->name);
+ kfree(gluebi);
+ return 0;
+}
+
+/**
+ * gluebi_updated - UBI volume was updated notifier.
+ * @vi: volume info structure
+ *
+ * This function is called every time an UBI volume is updated. It does nothing
+ * if te volume @vol is dynamic, and changes MTD device size if the
+ * volume is static. This is needed because static volumes cannot be read past
+ * data they contain. This function returns zero in case of success and a
+ * negative error code in case of error.
+ */
+static int gluebi_updated(struct ubi_volume_info *vi)
+{
+ struct gluebi_device *gluebi;
+
+ mutex_lock(&devices_mutex);
+ gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+ if (!gluebi) {
+ mutex_unlock(&devices_mutex);
+ err_msg("got update notification for unknown UBI device %d volume %d",
+ vi->ubi_num, vi->vol_id);
+ return -ENOENT;
+ }
+
+ if (vi->vol_type == UBI_STATIC_VOLUME)
+ gluebi->mtd.size = vi->used_bytes;
+ mutex_unlock(&devices_mutex);
+ return 0;
+}
+
+/**
+ * gluebi_resized - UBI volume was re-sized notifier.
+ * @vi: volume info structure
+ *
+ * This function is called every time an UBI volume is re-size. It changes the
+ * corresponding fake MTD device size. This function returns zero in case of
+ * success and a negative error code in case of error.
+ */
+static int gluebi_resized(struct ubi_volume_info *vi)
+{
+ struct gluebi_device *gluebi;
+
+ mutex_lock(&devices_mutex);
+ gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+ if (!gluebi) {
+ mutex_unlock(&devices_mutex);
+ err_msg("got update notification for unknown UBI device %d volume %d",
+ vi->ubi_num, vi->vol_id);
+ return -ENOENT;
+ }
+ gluebi->mtd.size = vi->used_bytes;
+ mutex_unlock(&devices_mutex);
+ return 0;
+}
+
+/**
+ * gluebi_notify - UBI notification handler.
+ * @nb: registered notifier block
+ * @l: notification type
+ * @ptr: pointer to the &struct ubi_notification object
+ */
+static int gluebi_notify(struct notifier_block *nb, unsigned long l,
+ void *ns_ptr)
+{
+ struct ubi_notification *nt = ns_ptr;
+
+ switch (l) {
+ case UBI_VOLUME_ADDED:
+ gluebi_create(&nt->di, &nt->vi);
+ break;
+ case UBI_VOLUME_REMOVED:
+ gluebi_remove(&nt->vi);
+ break;
+ case UBI_VOLUME_RESIZED:
+ gluebi_resized(&nt->vi);
+ break;
+ case UBI_VOLUME_UPDATED:
+ gluebi_updated(&nt->vi);
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block gluebi_notifier = {
+ .notifier_call = gluebi_notify,
+};
+
+static int __init ubi_gluebi_init(void)
+{
+ return ubi_register_volume_notifier(&gluebi_notifier, 0);
+}
+
+static void __exit ubi_gluebi_exit(void)
+{
+ struct gluebi_device *gluebi, *g;
+
+ list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) {
+ int err;
+ struct mtd_info *mtd = &gluebi->mtd;
+
+ err = mtd_device_unregister(mtd);
+ if (err)
+ err_msg("error %d while removing gluebi MTD device %d, UBI device %d, volume %d - ignoring",
+ err, mtd->index, gluebi->ubi_num,
+ gluebi->vol_id);
+ kfree(mtd->name);
+ kfree(gluebi);
+ }
+ ubi_unregister_volume_notifier(&gluebi_notifier);
+}
+
+module_init(ubi_gluebi_init);
+module_exit(ubi_gluebi_exit);
+MODULE_DESCRIPTION("MTD emulation layer over UBI volumes");
+MODULE_AUTHOR("Artem Bityutskiy, Joern Engel");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff