/*
   * Copyright (c) International Business Machines Corp., 2006
   * Copyright (c) Nokia Corporation, 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)
   *
   * Jan 2007: Alexander Schmidt, hacked per-volume update.
   */
  
  /*
   * This file contains implementation of the volume update and atomic LEB change
   * functionality.
   *
   * The update operation is based on the per-volume update marker which is
   * stored in the volume table. The update marker is set before the update
   * starts, and removed after the update has been finished. So if the update was
   * interrupted by an unclean re-boot or due to some other reasons, the update
   * marker stays on the flash media and UBI finds it when it attaches the MTD
   * device next time. If the update marker is set for a volume, the volume is
   * treated as damaged and most I/O operations are prohibited. Only a new update
   * operation is allowed.
   *
   * Note, in general it is possible to implement the update operation as a
   * transaction with a roll-back capability.
   */
  
  #include <linux/err.h>
  #include <linux/uaccess.h>
  #include <linux/math64.h>
  #include "ubi.h"
  
  /**
   * set_update_marker - set update marker.
   * @ubi: UBI device description object
   * @vol: volume description object
   *
   * This function sets the update marker flag for volume @vol. Returns zero
   * in case of success and a negative error code in case of failure.
   */
  static int set_update_marker(struct ubi_device *ubi, struct ubi_volume *vol)
  {
  	int err;
  	struct ubi_vtbl_record vtbl_rec;
  
  	dbg_gen("set update marker for volume %d", vol->vol_id);
  
  	if (vol->upd_marker) {
  		ubi_assert(ubi->vtbl[vol->vol_id].upd_marker);
  		dbg_gen("already set");
  		return 0;
  	}
  
  	vtbl_rec = ubi->vtbl[vol->vol_id];
  	vtbl_rec.upd_marker = 1;
  
  	mutex_lock(&ubi->device_mutex);
  	err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
  	vol->upd_marker = 1;
  	mutex_unlock(&ubi->device_mutex);
  	return err;
  }
  
  /**
   * clear_update_marker - clear update marker.
   * @ubi: UBI device description object
   * @vol: volume description object
   * @bytes: new data size in bytes
   *
   * This function clears the update marker for volume @vol, sets new volume
   * data size and clears the "corrupted" flag (static volumes only). Returns
   * zero in case of success and a negative error code in case of failure.
   */
  static int clear_update_marker(struct ubi_device *ubi, struct ubi_volume *vol,
  			       long long bytes)
  {
  	int err;
  	struct ubi_vtbl_record vtbl_rec;
  
  	dbg_gen("clear update marker for volume %d", vol->vol_id);
  
  	vtbl_rec = ubi->vtbl[vol->vol_id];
  	ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
  	vtbl_rec.upd_marker = 0;
  
  	if (vol->vol_type == UBI_STATIC_VOLUME) {
  		vol->corrupted = 0;
  		vol->used_bytes = bytes;
  		vol->used_ebs = div_u64_rem(bytes, vol->usable_leb_size,
  					    &vol->last_eb_bytes);
  		if (vol->last_eb_bytes)
  			vol->used_ebs += 1;
  		else
  			vol->last_eb_bytes = vol->usable_leb_size;
  	}
  
  	mutex_lock(&ubi->device_mutex);
  	err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
  	vol->upd_marker = 0;
  	mutex_unlock(&ubi->device_mutex);
  	return err;
  }
  
  /**
   * ubi_start_update - start volume update.
   * @ubi: UBI device description object
   * @vol: volume description object
   * @bytes: update bytes
   *
   * This function starts volume update operation. If @bytes is zero, the volume
   * is just wiped out. Returns zero in case of success and a negative error code
   * in case of failure.
   */
  int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
  		     long long bytes)
  {
  	int i, err;
  
  	dbg_gen("start update of volume %d, %llu bytes", vol->vol_id, bytes);
  	ubi_assert(!vol->updating && !vol->changing_leb);
  	vol->updating = 1;
  
  	err = set_update_marker(ubi, vol);
  	if (err)
  		return err;
  
  	/* Before updating - wipe out the volume */
  	for (i = 0; i < vol->reserved_pebs; i++) {
  		err = ubi_eba_unmap_leb(ubi, vol, i);
  		if (err)
  			return err;
  	}
  
  	if (bytes == 0) {
  		err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
  		if (err)
  			return err;
  
  		err = clear_update_marker(ubi, vol, 0);
  		if (err)
  			return err;
  		vol->updating = 0;
  		return 0;
  	}
  
  	vol->upd_buf = vmalloc(ubi->leb_size);
  	if (!vol->upd_buf)
  		return -ENOMEM;
  
  	vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
  			       vol->usable_leb_size);
  	vol->upd_bytes = bytes;
  	vol->upd_received = 0;
  	return 0;
  }
  
  /**
   * ubi_start_leb_change - start atomic LEB change.
   * @ubi: UBI device description object
   * @vol: volume description object
   * @req: operation request
   *
   * This function starts atomic LEB change operation. Returns zero in case of
   * success and a negative error code in case of failure.
   */
  int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
  			 const struct ubi_leb_change_req *req)
  {
  	ubi_assert(!vol->updating && !vol->changing_leb);
  
  	dbg_gen("start changing LEB %d:%d, %u bytes",
  		vol->vol_id, req->lnum, req->bytes);
  	if (req->bytes == 0)
  		return ubi_eba_atomic_leb_change(ubi, vol, req->lnum, NULL, 0);
  
  	vol->upd_bytes = req->bytes;
  	vol->upd_received = 0;
  	vol->changing_leb = 1;
  	vol->ch_lnum = req->lnum;
  
  	vol->upd_buf = vmalloc(req->bytes);
  	if (!vol->upd_buf)
  		return -ENOMEM;
  
  	return 0;
  }
  
  /**
   * write_leb - write update data.
   * @ubi: UBI device description object
   * @vol: volume description object
   * @lnum: logical eraseblock number
   * @buf: data to write
   * @len: data size
   * @used_ebs: how many logical eraseblocks will this volume contain (static
   * volumes only)
   *
   * This function writes update data to corresponding logical eraseblock. In
   * case of dynamic volume, this function checks if the data contains 0xFF bytes
   * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
   * buffer contains only 0xFF bytes, the LEB is left unmapped.
   *
   * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
   * that we want to make sure that more data may be appended to the logical
   * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
   * this PEB won't be writable anymore. So if one writes the file-system image
   * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
   * space is writable after the update.
   *
   * We do not do this for static volumes because they are read-only. But this
   * also cannot be done because we have to store per-LEB CRC and the correct
   * data length.
   *
   * This function returns zero in case of success and a negative error code in
   * case of failure.
   */
  static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
  		     void *buf, int len, int used_ebs)
  {
  	int err;
  
  	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
  		int l = ALIGN(len, ubi->min_io_size);
  
  		memset(buf + len, 0xFF, l - len);
  		len = ubi_calc_data_len(ubi, buf, l);
  		if (len == 0) {
  			dbg_gen("all %d bytes contain 0xFF - skip", len);
  			return 0;
  		}
  
  		err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len);
  	} else {
  		/*
  		 * When writing static volume, and this is the last logical
  		 * eraseblock, the length (@len) does not have to be aligned to
  		 * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
  		 * function accepts exact (unaligned) length and stores it in
  		 * the VID header. And it takes care of proper alignment by
  		 * padding the buffer. Here we just make sure the padding will
  		 * contain zeros, not random trash.
  		 */
  		memset(buf + len, 0, vol->usable_leb_size - len);
  		err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len, used_ebs);
  	}
  
  	return err;
  }
  
  /**
   * ubi_more_update_data - write more update data.
   * @ubi: UBI device description object
   * @vol: volume description object
   * @buf: write data (user-space memory buffer)
   * @count: how much bytes to write
   *
   * This function writes more data to the volume which is being updated. It may
   * be called arbitrary number of times until all the update data arriveis. This
   * function returns %0 in case of success, number of bytes written during the
   * last call if the whole volume update has been successfully finished, and a
   * negative error code in case of failure.
   */
  int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
  			 const void __user *buf, int count)
  {
  	int lnum, offs, err = 0, len, to_write = count;
  
  	dbg_gen("write %d of %lld bytes, %lld already passed",
  		count, vol->upd_bytes, vol->upd_received);
  
  	if (ubi->ro_mode)
  		return -EROFS;
  
  	lnum = div_u64_rem(vol->upd_received,  vol->usable_leb_size, &offs);
  	if (vol->upd_received + count > vol->upd_bytes)
  		to_write = count = vol->upd_bytes - vol->upd_received;
  
  	/*
  	 * When updating volumes, we accumulate whole logical eraseblock of
  	 * data and write it at once.
  	 */
  	if (offs != 0) {
  		/*
  		 * This is a write to the middle of the logical eraseblock. We
  		 * copy the data to our update buffer and wait for more data or
  		 * flush it if the whole eraseblock is written or the update
  		 * is finished.
  		 */
  
  		len = vol->usable_leb_size - offs;
  		if (len > count)
  			len = count;
  
  		err = copy_from_user(vol->upd_buf + offs, buf, len);
  		if (err)
  			return -EFAULT;
  
  		if (offs + len == vol->usable_leb_size ||
  		    vol->upd_received + len == vol->upd_bytes) {
  			int flush_len = offs + len;
  
  			/*
  			 * OK, we gathered either the whole eraseblock or this
  			 * is the last chunk, it's time to flush the buffer.
  			 */
  			ubi_assert(flush_len <= vol->usable_leb_size);
  			err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
  					vol->upd_ebs);
  			if (err)
  				return err;
  		}
  
  		vol->upd_received += len;
  		count -= len;
  		buf += len;
  		lnum += 1;
  	}
  
  	/*
  	 * If we've got more to write, let's continue. At this point we know we
  	 * are starting from the beginning of an eraseblock.
  	 */
  	while (count) {
  		if (count > vol->usable_leb_size)
  			len = vol->usable_leb_size;
  		else
  			len = count;
  
  		err = copy_from_user(vol->upd_buf, buf, len);
  		if (err)
  			return -EFAULT;
  
  		if (len == vol->usable_leb_size ||
  		    vol->upd_received + len == vol->upd_bytes) {
  			err = write_leb(ubi, vol, lnum, vol->upd_buf,
  					len, vol->upd_ebs);
  			if (err)
  				break;
  		}
  
  		vol->upd_received += len;
  		count -= len;
  		lnum += 1;
  		buf += len;
  	}
  
  	ubi_assert(vol->upd_received <= vol->upd_bytes);
  	if (vol->upd_received == vol->upd_bytes) {
  		err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
  		if (err)
  			return err;
  		/* The update is finished, clear the update marker */
  		err = clear_update_marker(ubi, vol, vol->upd_bytes);
  		if (err)
  			return err;
  		vol->updating = 0;
  		err = to_write;
  		vfree(vol->upd_buf);
  	}
  
  	return err;
  }
  
  /**
   * ubi_more_leb_change_data - accept more data for atomic LEB change.
   * @ubi: UBI device description object
   * @vol: volume description object
   * @buf: write data (user-space memory buffer)
   * @count: how much bytes to write
   *
   * This function accepts more data to the volume which is being under the
   * "atomic LEB change" operation. It may be called arbitrary number of times
   * until all data arrives. This function returns %0 in case of success, number
   * of bytes written during the last call if the whole "atomic LEB change"
   * operation has been successfully finished, and a negative error code in case
   * of failure.
   */
  int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
  			     const void __user *buf, int count)
  {
  	int err;
  
  	dbg_gen("write %d of %lld bytes, %lld already passed",
  		count, vol->upd_bytes, vol->upd_received);
  
  	if (ubi->ro_mode)
  		return -EROFS;
  
  	if (vol->upd_received + count > vol->upd_bytes)
  		count = vol->upd_bytes - vol->upd_received;
  
  	err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
  	if (err)
  		return -EFAULT;
  
  	vol->upd_received += count;
  
  	if (vol->upd_received == vol->upd_bytes) {
  		int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);
  
  		memset(vol->upd_buf + vol->upd_bytes, 0xFF,
  		       len - vol->upd_bytes);
  		len = ubi_calc_data_len(ubi, vol->upd_buf, len);
  		err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
  						vol->upd_buf, len);
  		if (err)
  			return err;
  	}
  
  	ubi_assert(vol->upd_received <= vol->upd_bytes);
  	if (vol->upd_received == vol->upd_bytes) {
  		vol->changing_leb = 0;
  		err = count;
  		vfree(vol->upd_buf);
  	}
  
  	return err;
  }