vmt.c

基于linux-2.6.28的mtd驱动

/*
 * 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)
 */

/*
 * This file contains implementation of volume creation, deletion, updating and
 * resizing.
 */

#include <linux/err.h>
#include <asm/div64.h>
#include "ubi.h"

#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
static int paranoid_check_volumes(struct ubi_device *ubi);
#else
#define paranoid_check_volumes(ubi) 0
#endif

static ssize_t vol_attribute_show(struct device *dev,
				  struct device_attribute *attr, char *buf);

/* Device attributes corresponding to files in '/<sysfs>/class/ubi/ubiX_Y' */
static struct device_attribute attr_vol_reserved_ebs =
	__ATTR(reserved_ebs, S_IRUGO, vol_attribute_show, NULL);
static struct device_attribute attr_vol_type =
	__ATTR(type, S_IRUGO, vol_attribute_show, NULL);
static struct device_attribute attr_vol_name =
	__ATTR(name, S_IRUGO, vol_attribute_show, NULL);
static struct device_attribute attr_vol_corrupted =
	__ATTR(corrupted, S_IRUGO, vol_attribute_show, NULL);
static struct device_attribute attr_vol_alignment =
	__ATTR(alignment, S_IRUGO, vol_attribute_show, NULL);
static struct device_attribute attr_vol_usable_eb_size =
	__ATTR(usable_eb_size, S_IRUGO, vol_attribute_show, NULL);
static struct device_attribute attr_vol_data_bytes =
	__ATTR(data_bytes, S_IRUGO, vol_attribute_show, NULL);
static struct device_attribute attr_vol_upd_marker =
	__ATTR(upd_marker, S_IRUGO, vol_attribute_show, NULL);

/*
 * "Show" method for files in '/<sysfs>/class/ubi/ubiX_Y/'.
 *
 * Consider a situation:
 * A. process 1 opens a sysfs file related to volume Y, say
 *    /<sysfs>/class/ubi/ubiX_Y/reserved_ebs;
 * B. process 2 removes volume Y;
 * C. process 1 starts reading the /<sysfs>/class/ubi/ubiX_Y/reserved_ebs file;
 *
 * In this situation, this function will return %-ENODEV because it will find
 * out that the volume was removed from the @ubi->volumes array.
 */
static ssize_t vol_attribute_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	int ret;
	struct ubi_volume *vol = container_of(dev, struct ubi_volume, dev);
	struct ubi_device *ubi;

	ubi = ubi_get_device(vol->ubi->ubi_num);
	if (!ubi)
		return -ENODEV;

	spin_lock(&ubi->volumes_lock);
	if (!ubi->volumes[vol->vol_id]) {
		spin_unlock(&ubi->volumes_lock);
		ubi_put_device(ubi);
		return -ENODEV;
	}
	/* Take a reference to prevent volume removal */
	vol->ref_count += 1;
	spin_unlock(&ubi->volumes_lock);

	if (attr == &attr_vol_reserved_ebs)
		ret = sprintf(buf, "%d\n", vol->reserved_pebs);
	else if (attr == &attr_vol_type) {
		const char *tp;

		if (vol->vol_type == UBI_DYNAMIC_VOLUME)
			tp = "dynamic";
		else
			tp = "static";
		ret = sprintf(buf, "%s\n", tp);
	} else if (attr == &attr_vol_name)
		ret = sprintf(buf, "%s\n", vol->name);
	else if (attr == &attr_vol_corrupted)
		ret = sprintf(buf, "%d\n", vol->corrupted);
	else if (attr == &attr_vol_alignment)
		ret = sprintf(buf, "%d\n", vol->alignment);
	else if (attr == &attr_vol_usable_eb_size)
		ret = sprintf(buf, "%d\n", vol->usable_leb_size);
	else if (attr == &attr_vol_data_bytes)
		ret = sprintf(buf, "%lld\n", vol->used_bytes);
	else if (attr == &attr_vol_upd_marker)
		ret = sprintf(buf, "%d\n", vol->upd_marker);
	else
		/* This must be a bug */
		ret = -EINVAL;

	/* We've done the operation, drop volume and UBI device references */
	spin_lock(&ubi->volumes_lock);
	vol->ref_count -= 1;
	ubi_assert(vol->ref_count >= 0);
	spin_unlock(&ubi->volumes_lock);
	ubi_put_device(ubi);
	return ret;
}

/* Release method for volume devices */
static void vol_release(struct device *dev)
{
	struct ubi_volume *vol = container_of(dev, struct ubi_volume, dev);

	kfree(vol->eba_tbl);
	kfree(vol);
}

/**
 * volume_sysfs_init - initialize sysfs for new volume.
 * @ubi: UBI device description object
 * @vol: volume description object
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 *
 * Note, this function does not free allocated resources in case of failure -
 * the caller does it. This is because this would cause release() here and the
 * caller would oops.
 */
static int volume_sysfs_init(struct ubi_device *ubi, struct ubi_volume *vol)
{
	int err;

	err = device_create_file(&vol->dev, &attr_vol_reserved_ebs);
	if (err)
		return err;
	err = device_create_file(&vol->dev, &attr_vol_type);
	if (err)
		return err;
	err = device_create_file(&vol->dev, &attr_vol_name);
	if (err)
		return err;
	err = device_create_file(&vol->dev, &attr_vol_corrupted);
	if (err)
		return err;
	err = device_create_file(&vol->dev, &attr_vol_alignment);
	if (err)
		return err;
	err = device_create_file(&vol->dev, &attr_vol_usable_eb_size);
	if (err)
		return err;
	err = device_create_file(&vol->dev, &attr_vol_data_bytes);
	if (err)
		return err;
	err = device_create_file(&vol->dev, &attr_vol_upd_marker);
	return err;
}

/**
 * volume_sysfs_close - close sysfs for a volume.
 * @vol: volume description object
 */
static void volume_sysfs_close(struct ubi_volume *vol)
{
	device_remove_file(&vol->dev, &attr_vol_upd_marker);
	device_remove_file(&vol->dev, &attr_vol_data_bytes);
	device_remove_file(&vol->dev, &attr_vol_usable_eb_size);
	device_remove_file(&vol->dev, &attr_vol_alignment);
	device_remove_file(&vol->dev, &attr_vol_corrupted);
	device_remove_file(&vol->dev, &attr_vol_name);
	device_remove_file(&vol->dev, &attr_vol_type);
	device_remove_file(&vol->dev, &attr_vol_reserved_ebs);
	device_unregister(&vol->dev);
}

/**
 * ubi_create_volume - create volume.
 * @ubi: UBI device description object
 * @req: volume creation request
 *
 * This function creates volume described by @req. If @req->vol_id id
 * %UBI_VOL_NUM_AUTO, this function automatically assign ID to the new volume
 * and saves it in @req->vol_id. Returns zero in case of success and a negative
 * error code in case of failure. Note, the caller has to have the
 * @ubi->volumes_mutex locked.
 */
int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
{
	int i, err, vol_id = req->vol_id, do_free = 1;
	struct ubi_volume *vol;
	struct ubi_vtbl_record vtbl_rec;
	uint64_t bytes;
	dev_t dev;

	if (ubi->ro_mode)
		return -EROFS;

	vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
	if (!vol)
		return -ENOMEM;

	spin_lock(&ubi->volumes_lock);
	if (vol_id == UBI_VOL_NUM_AUTO) {
		/* Find unused volume ID */
		dbg_gen("search for vacant volume ID");
		for (i = 0; i < ubi->vtbl_slots; i++)
			if (!ubi->volumes[i]) {
				vol_id = i;
				break;
			}

		if (vol_id == UBI_VOL_NUM_AUTO) {
			dbg_err("out of volume IDs");
			err = -ENFILE;
			goto out_unlock;
		}
		req->vol_id = vol_id;
	}

	dbg_gen("volume ID %d, %llu bytes, type %d, name %s",
		vol_id, (unsigned long long)req->bytes,
		(int)req->vol_type, req->name);

	/* Ensure that this volume does not exist */
	err = -EEXIST;
	if (ubi->volumes[vol_id]) {
		dbg_err("volume %d already exists", vol_id);
		goto out_unlock;
	}

	/* Ensure that the name is unique */
	for (i = 0; i < ubi->vtbl_slots; i++)
		if (ubi->volumes[i] &&
		    ubi->volumes[i]->name_len == req->name_len &&
		    !strcmp(ubi->volumes[i]->name, req->name)) {
			dbg_err("volume \"%s\" exists (ID %d)", req->name, i);
			goto out_unlock;
		}

	/* Calculate how many eraseblocks are requested */
	vol->usable_leb_size = ubi->leb_size - ubi->leb_size % req->alignment;
	bytes = req->bytes;
	if (do_div(bytes, vol->usable_leb_size))
		vol->reserved_pebs = 1;
	vol->reserved_pebs += bytes;

	/* Reserve physical eraseblocks */
	if (vol->reserved_pebs > ubi->avail_pebs) {
		dbg_err("not enough PEBs, only %d available", ubi->avail_pebs);
		err = -ENOSPC;
		goto out_unlock;
	}
	ubi->avail_pebs -= vol->reserved_pebs;
	ubi->rsvd_pebs += vol->reserved_pebs;
	spin_unlock(&ubi->volumes_lock);

	vol->vol_id    = vol_id;
	vol->alignment = req->alignment;
	vol->data_pad  = ubi->leb_size % vol->alignment;
	vol->vol_type  = req->vol_type;
	vol->name_len  = req->name_len;
	memcpy(vol->name, req->name, vol->name_len);
	vol->ubi = ubi;

	/*
	 * Finish all pending erases because there may be some LEBs belonging
	 * to the same volume ID.
	 */
	err = ubi_wl_flush(ubi);
	if (err)
		goto out_acc;

	vol->eba_tbl = kmalloc(vol->reserved_pebs * sizeof(int), GFP_KERNEL);
	if (!vol->eba_tbl) {
		err = -ENOMEM;
		goto out_acc;
	}

	for (i = 0; i < vol->reserved_pebs; i++)
		vol->eba_tbl[i] = UBI_LEB_UNMAPPED;

	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
		vol->used_ebs = vol->reserved_pebs;
		vol->last_eb_bytes = vol->usable_leb_size;
		vol->used_bytes =
			(long long)vol->used_ebs * vol->usable_leb_size;
	} else {
		bytes = vol->used_bytes;
		vol->last_eb_bytes = do_div(bytes, vol->usable_leb_size);
		vol->used_ebs = bytes;
		if (vol->last_eb_bytes)
			vol->used_ebs += 1;
		else
			vol->last_eb_bytes = vol->usable_leb_size;
	}

	/* Register character device for the volume */
	cdev_init(&vol->cdev, &ubi_vol_cdev_operations);
	vol->cdev.owner = THIS_MODULE;
	dev = MKDEV(MAJOR(ubi->cdev.dev), vol_id + 1);
	err = cdev_add(&vol->cdev, dev, 1);
	if (err) {
		ubi_err("cannot add character device");
		goto out_mapping;
	}

	err = ubi_create_gluebi(ubi, vol);
	if (err)
		goto out_cdev;

	vol->dev.release = vol_release;
	vol->dev.parent = &ubi->dev;
	vol->dev.devt = dev;
	vol->dev.class = ubi_class;

	sprintf(&vol->dev.bus_id[0], "%s_%d", ubi->ubi_name, vol->vol_id);
	err = device_register(&vol->dev);
	if (err) {
		ubi_err("cannot register device");
		goto out_gluebi;
	}

	err = volume_sysfs_init(ubi, vol);
	if (err)
		goto out_sysfs;

	/* Fill volume table record */
	memset(&vtbl_rec, 0, sizeof(struct ubi_vtbl_record));
	vtbl_rec.reserved_pebs = cpu_to_be32(vol->reserved_pebs);
	vtbl_rec.alignment     = cpu_to_be32(vol->alignment);
	vtbl_rec.data_pad      = cpu_to_be32(vol->data_pad);
	vtbl_rec.name_len      = cpu_to_be16(vol->name_len);
	if (vol->vol_type == UBI_DYNAMIC_VOLUME)
		vtbl_rec.vol_type = UBI_VID_DYNAMIC;
	else
		vtbl_rec.vol_type = UBI_VID_STATIC;
	memcpy(vtbl_rec.name, vol->name, vol->name_len);

	err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
	if (err)
		goto out_sysfs;

	spin_lock(&ubi->volumes_lock);
	ubi->volumes[vol_id] = vol;
	ubi->vol_count += 1;
	spin_unlock(&ubi->volumes_lock);

	err = paranoid_check_volumes(ubi);
	return err;

out_sysfs:
	/*
	 * We have registered our device, we should not free the volume
	 * description object in this function in case of an error - it is
	 * freed by the release function.
	 *
	 * Get device reference to prevent the release function from being
	 * called just after sysfs has been closed.
	 */
	do_free = 0;
	get_device(&vol->dev);
	volume_sysfs_close(vol);
out_gluebi:
	if (ubi_destroy_gluebi(vol))
		dbg_err("cannot destroy gluebi for volume %d:%d",
			ubi->ubi_num, vol_id);
out_cdev:
	cdev_del(&vol->cdev);
out_mapping:
	if (do_free)
		kfree(vol->eba_tbl);
out_acc:
	spin_lock(&ubi->volumes_lock);
	ubi->rsvd_pebs -= vol->reserved_pebs;
	ubi->avail_pebs += vol->reserved_pebs;
out_unlock:
	spin_unlock(&ubi->volumes_lock);
	if (do_free)
		kfree(vol);
	else
		put_device(&vol->dev);
	ubi_err("cannot create volume %d, error %d", vol_id, err);
	return err;
}

/**
 * ubi_remove_volume - remove volume.
 * @desc: volume descriptor
 * @no_vtbl: do not change volume table if not zero
 *
 * This function removes volume described by @desc. The volume has to be opened
 * in "exclusive" mode. Returns zero in case of success and a negative error
 * code in case of failure. The caller has to have the @ubi->volumes_mutex
 * locked.
 */
int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl)
{
	struct ubi_volume *vol = desc->vol;
	struct ubi_device *ubi = vol->ubi;
	int i, err, vol_id = vol->vol_id, reserved_pebs = vol->reserved_pebs;

	dbg_gen("remove UBI volume %d", vol_id);
	ubi_assert(desc->mode == UBI_EXCLUSIVE);
	ubi_assert(vol == ubi->volumes[vol_id]);

	if (ubi->ro_mode)
		return -EROFS;

	spin_lock(&ubi->volumes_lock);
	if (vol->ref_count > 1) {
		/*
		 * The volume is busy, probably someone is reading one of its
		 * sysfs files.
		 */
		err = -EBUSY;
		goto out_unlock;
	}
	ubi->volumes[vol_id] = NULL;
	spin_unlock(&ubi->volumes_lock);

	err = ubi_destroy_gluebi(vol);
	if (err)
		goto out_err;

	if (!no_vtbl) {
		err = ubi_change_vtbl_record(ubi, vol_id, NULL);
		if (err)
			goto out_err;
	}

	for (i = 0; i < vol->reserved_pebs; i++) {
		err = ubi_eba_unmap_leb(ubi, vol, i);
		if (err)