/*
   * This file is part of UBIFS.
   *
   * Copyright (C) 2006-2008 Nokia Corporation.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   *
   * 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., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
   *
   * Authors: Artem Bityutskiy (Битюцкий Артём)
   *          Adrian Hunter
   */
  
  /*
   * This file implements UBIFS initialization and VFS superblock operations. Some
   * initialization stuff which is rather large and complex is placed at
   * corresponding subsystems, but most of it is here.
   */
  
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/ctype.h>

  #include <linux/kthread.h>
  #include <linux/parser.h>
  #include <linux/seq_file.h>
  #include <linux/mount.h>

  #include <linux/math64.h>

  #include <linux/writeback.h>

  #include "ubifs.h"

  /*
   * Maximum amount of memory we may 'kmalloc()' without worrying that we are
   * allocating too much.
   */
  #define UBIFS_KMALLOC_OK (128*1024)

  /* Slab cache for UBIFS inodes */
  struct kmem_cache *ubifs_inode_slab;
  
  /* UBIFS TNC shrinker description */
  static struct shrinker ubifs_shrinker_info = {
  	.shrink = ubifs_shrinker,
  	.seeks = DEFAULT_SEEKS,
  };
  
  /**
   * validate_inode - validate inode.
   * @c: UBIFS file-system description object
   * @inode: the inode to validate
   *
   * This is a helper function for 'ubifs_iget()' which validates various fields
   * of a newly built inode to make sure they contain sane values and prevent
   * possible vulnerabilities. Returns zero if the inode is all right and
   * a non-zero error code if not.
   */
  static int validate_inode(struct ubifs_info *c, const struct inode *inode)
  {
  	int err;
  	const struct ubifs_inode *ui = ubifs_inode(inode);
  
  	if (inode->i_size > c->max_inode_sz) {
  		ubifs_err("inode is too large (%lld)",
  			  (long long)inode->i_size);
  		return 1;
  	}
  
  	if (ui->compr_type < 0 || ui->compr_type >= UBIFS_COMPR_TYPES_CNT) {
  		ubifs_err("unknown compression type %d", ui->compr_type);
  		return 2;
  	}
  
  	if (ui->xattr_names + ui->xattr_cnt > XATTR_LIST_MAX)
  		return 3;
  
  	if (ui->data_len < 0 || ui->data_len > UBIFS_MAX_INO_DATA)
  		return 4;

  	if (ui->xattr && !S_ISREG(inode->i_mode))

  		return 5;
  
  	if (!ubifs_compr_present(ui->compr_type)) {
  		ubifs_warn("inode %lu uses '%s' compression, but it was not "
  			   "compiled in", inode->i_ino,
  			   ubifs_compr_name(ui->compr_type));
  	}

  	err = dbg_check_dir(c, inode);

  	return err;
  }
  
  struct inode *ubifs_iget(struct super_block *sb, unsigned long inum)
  {
  	int err;
  	union ubifs_key key;
  	struct ubifs_ino_node *ino;
  	struct ubifs_info *c = sb->s_fs_info;
  	struct inode *inode;
  	struct ubifs_inode *ui;
  
  	dbg_gen("inode %lu", inum);
  
  	inode = iget_locked(sb, inum);
  	if (!inode)
  		return ERR_PTR(-ENOMEM);
  	if (!(inode->i_state & I_NEW))
  		return inode;
  	ui = ubifs_inode(inode);
  
  	ino = kmalloc(UBIFS_MAX_INO_NODE_SZ, GFP_NOFS);
  	if (!ino) {
  		err = -ENOMEM;
  		goto out;
  	}
  
  	ino_key_init(c, &key, inode->i_ino);
  
  	err = ubifs_tnc_lookup(c, &key, ino);
  	if (err)
  		goto out_ino;
  
  	inode->i_flags |= (S_NOCMTIME | S_NOATIME);

  	set_nlink(inode, le32_to_cpu(ino->nlink));

  	inode->i_uid   = le32_to_cpu(ino->uid);
  	inode->i_gid   = le32_to_cpu(ino->gid);
  	inode->i_atime.tv_sec  = (int64_t)le64_to_cpu(ino->atime_sec);
  	inode->i_atime.tv_nsec = le32_to_cpu(ino->atime_nsec);
  	inode->i_mtime.tv_sec  = (int64_t)le64_to_cpu(ino->mtime_sec);
  	inode->i_mtime.tv_nsec = le32_to_cpu(ino->mtime_nsec);
  	inode->i_ctime.tv_sec  = (int64_t)le64_to_cpu(ino->ctime_sec);
  	inode->i_ctime.tv_nsec = le32_to_cpu(ino->ctime_nsec);
  	inode->i_mode = le32_to_cpu(ino->mode);
  	inode->i_size = le64_to_cpu(ino->size);
  
  	ui->data_len    = le32_to_cpu(ino->data_len);
  	ui->flags       = le32_to_cpu(ino->flags);
  	ui->compr_type  = le16_to_cpu(ino->compr_type);
  	ui->creat_sqnum = le64_to_cpu(ino->creat_sqnum);
  	ui->xattr_cnt   = le32_to_cpu(ino->xattr_cnt);
  	ui->xattr_size  = le32_to_cpu(ino->xattr_size);
  	ui->xattr_names = le32_to_cpu(ino->xattr_names);
  	ui->synced_i_size = ui->ui_size = inode->i_size;
  
  	ui->xattr = (ui->flags & UBIFS_XATTR_FL) ? 1 : 0;
  
  	err = validate_inode(c, inode);
  	if (err)
  		goto out_invalid;

  	/* Disable read-ahead */

  	inode->i_mapping->backing_dev_info = &c->bdi;
  
  	switch (inode->i_mode & S_IFMT) {
  	case S_IFREG:
  		inode->i_mapping->a_ops = &ubifs_file_address_operations;
  		inode->i_op = &ubifs_file_inode_operations;
  		inode->i_fop = &ubifs_file_operations;
  		if (ui->xattr) {
  			ui->data = kmalloc(ui->data_len + 1, GFP_NOFS);
  			if (!ui->data) {
  				err = -ENOMEM;
  				goto out_ino;
  			}
  			memcpy(ui->data, ino->data, ui->data_len);
  			((char *)ui->data)[ui->data_len] = '\0';
  		} else if (ui->data_len != 0) {
  			err = 10;
  			goto out_invalid;
  		}
  		break;
  	case S_IFDIR:
  		inode->i_op  = &ubifs_dir_inode_operations;
  		inode->i_fop = &ubifs_dir_operations;
  		if (ui->data_len != 0) {
  			err = 11;
  			goto out_invalid;
  		}
  		break;
  	case S_IFLNK:
  		inode->i_op = &ubifs_symlink_inode_operations;
  		if (ui->data_len <= 0 || ui->data_len > UBIFS_MAX_INO_DATA) {
  			err = 12;
  			goto out_invalid;
  		}
  		ui->data = kmalloc(ui->data_len + 1, GFP_NOFS);
  		if (!ui->data) {
  			err = -ENOMEM;
  			goto out_ino;
  		}
  		memcpy(ui->data, ino->data, ui->data_len);
  		((char *)ui->data)[ui->data_len] = '\0';
  		break;
  	case S_IFBLK:
  	case S_IFCHR:
  	{
  		dev_t rdev;
  		union ubifs_dev_desc *dev;
  
  		ui->data = kmalloc(sizeof(union ubifs_dev_desc), GFP_NOFS);
  		if (!ui->data) {
  			err = -ENOMEM;
  			goto out_ino;
  		}
  
  		dev = (union ubifs_dev_desc *)ino->data;
  		if (ui->data_len == sizeof(dev->new))
  			rdev = new_decode_dev(le32_to_cpu(dev->new));
  		else if (ui->data_len == sizeof(dev->huge))
  			rdev = huge_decode_dev(le64_to_cpu(dev->huge));
  		else {
  			err = 13;
  			goto out_invalid;
  		}
  		memcpy(ui->data, ino->data, ui->data_len);
  		inode->i_op = &ubifs_file_inode_operations;
  		init_special_inode(inode, inode->i_mode, rdev);
  		break;
  	}
  	case S_IFSOCK:
  	case S_IFIFO:
  		inode->i_op = &ubifs_file_inode_operations;
  		init_special_inode(inode, inode->i_mode, 0);
  		if (ui->data_len != 0) {
  			err = 14;
  			goto out_invalid;
  		}
  		break;
  	default:
  		err = 15;
  		goto out_invalid;
  	}
  
  	kfree(ino);
  	ubifs_set_inode_flags(inode);
  	unlock_new_inode(inode);
  	return inode;
  
  out_invalid:
  	ubifs_err("inode %lu validation failed, error %d", inode->i_ino, err);
  	dbg_dump_node(c, ino);
  	dbg_dump_inode(c, inode);
  	err = -EINVAL;
  out_ino:
  	kfree(ino);
  out:
  	ubifs_err("failed to read inode %lu, error %d", inode->i_ino, err);
  	iget_failed(inode);
  	return ERR_PTR(err);
  }
  
  static struct inode *ubifs_alloc_inode(struct super_block *sb)
  {
  	struct ubifs_inode *ui;
  
  	ui = kmem_cache_alloc(ubifs_inode_slab, GFP_NOFS);
  	if (!ui)
  		return NULL;
  
  	memset((void *)ui + sizeof(struct inode), 0,
  	       sizeof(struct ubifs_inode) - sizeof(struct inode));
  	mutex_init(&ui->ui_mutex);
  	spin_lock_init(&ui->ui_lock);
  	return &ui->vfs_inode;
  };

  static void ubifs_i_callback(struct rcu_head *head)
  {
  	struct inode *inode = container_of(head, struct inode, i_rcu);
  	struct ubifs_inode *ui = ubifs_inode(inode);

  	kmem_cache_free(ubifs_inode_slab, ui);
  }

  static void ubifs_destroy_inode(struct inode *inode)
  {
  	struct ubifs_inode *ui = ubifs_inode(inode);
  
  	kfree(ui->data);

  	call_rcu(&inode->i_rcu, ubifs_i_callback);

  }
  
  /*
   * Note, Linux write-back code calls this without 'i_mutex'.
   */

  static int ubifs_write_inode(struct inode *inode, struct writeback_control *wbc)

  {

  	int err = 0;

  	struct ubifs_info *c = inode->i_sb->s_fs_info;
  	struct ubifs_inode *ui = ubifs_inode(inode);
  
  	ubifs_assert(!ui->xattr);
  	if (is_bad_inode(inode))
  		return 0;
  
  	mutex_lock(&ui->ui_mutex);
  	/*
  	 * Due to races between write-back forced by budgeting
  	 * (see 'sync_some_inodes()') and pdflush write-back, the inode may
  	 * have already been synchronized, do not do this again. This might
  	 * also happen if it was synchronized in an VFS operation, e.g.
  	 * 'ubifs_link()'.
  	 */
  	if (!ui->dirty) {
  		mutex_unlock(&ui->ui_mutex);
  		return 0;
  	}

  	/*
  	 * As an optimization, do not write orphan inodes to the media just
  	 * because this is not needed.
  	 */
  	dbg_gen("inode %lu, mode %#x, nlink %u",
  		inode->i_ino, (int)inode->i_mode, inode->i_nlink);
  	if (inode->i_nlink) {

  		err = ubifs_jnl_write_inode(c, inode);

  		if (err)
  			ubifs_err("can't write inode %lu, error %d",
  				  inode->i_ino, err);

  		else
  			err = dbg_check_inode_size(c, inode, ui->ui_size);

  	}

  
  	ui->dirty = 0;
  	mutex_unlock(&ui->ui_mutex);
  	ubifs_release_dirty_inode_budget(c, ui);
  	return err;
  }

  static void ubifs_evict_inode(struct inode *inode)

  {
  	int err;
  	struct ubifs_info *c = inode->i_sb->s_fs_info;

  	struct ubifs_inode *ui = ubifs_inode(inode);

  	if (ui->xattr)

  		/*
  		 * Extended attribute inode deletions are fully handled in
  		 * 'ubifs_removexattr()'. These inodes are special and have
  		 * limited usage, so there is nothing to do here.
  		 */
  		goto out;

  	dbg_gen("inode %lu, mode %#x", inode->i_ino, (int)inode->i_mode);

  	ubifs_assert(!atomic_read(&inode->i_count));

  
  	truncate_inode_pages(&inode->i_data, 0);

  
  	if (inode->i_nlink)
  		goto done;

  	if (is_bad_inode(inode))
  		goto out;

  	ui->ui_size = inode->i_size = 0;

  	err = ubifs_jnl_delete_inode(c, inode);

  	if (err)
  		/*
  		 * Worst case we have a lost orphan inode wasting space, so a

  		 * simple error message is OK here.

  		 */

  		ubifs_err("can't delete inode %lu, error %d",
  			  inode->i_ino, err);

  out:

  	if (ui->dirty)
  		ubifs_release_dirty_inode_budget(c, ui);

  	else {
  		/* We've deleted something - clean the "no space" flags */

  		c->bi.nospace = c->bi.nospace_rp = 0;

  		smp_wmb();
  	}

  done:
  	end_writeback(inode);

  }

  static void ubifs_dirty_inode(struct inode *inode, int flags)

  {
  	struct ubifs_inode *ui = ubifs_inode(inode);
  
  	ubifs_assert(mutex_is_locked(&ui->ui_mutex));
  	if (!ui->dirty) {
  		ui->dirty = 1;
  		dbg_gen("inode %lu",  inode->i_ino);
  	}
  }
  
  static int ubifs_statfs(struct dentry *dentry, struct kstatfs *buf)
  {
  	struct ubifs_info *c = dentry->d_sb->s_fs_info;
  	unsigned long long free;

  	__le32 *uuid = (__le32 *)c->uuid;

  	free = ubifs_get_free_space(c);

  	dbg_gen("free space %lld bytes (%lld blocks)",
  		free, free >> UBIFS_BLOCK_SHIFT);
  
  	buf->f_type = UBIFS_SUPER_MAGIC;
  	buf->f_bsize = UBIFS_BLOCK_SIZE;
  	buf->f_blocks = c->block_cnt;
  	buf->f_bfree = free >> UBIFS_BLOCK_SHIFT;
  	if (free > c->report_rp_size)
  		buf->f_bavail = (free - c->report_rp_size) >> UBIFS_BLOCK_SHIFT;
  	else
  		buf->f_bavail = 0;
  	buf->f_files = 0;
  	buf->f_ffree = 0;
  	buf->f_namelen = UBIFS_MAX_NLEN;

  	buf->f_fsid.val[0] = le32_to_cpu(uuid[0]) ^ le32_to_cpu(uuid[2]);
  	buf->f_fsid.val[1] = le32_to_cpu(uuid[1]) ^ le32_to_cpu(uuid[3]);

  	ubifs_assert(buf->f_bfree <= c->block_cnt);

  	return 0;
  }

  static int ubifs_show_options(struct seq_file *s, struct dentry *root)

  {

  	struct ubifs_info *c = root->d_sb->s_fs_info;

  
  	if (c->mount_opts.unmount_mode == 2)
  		seq_printf(s, ",fast_unmount");
  	else if (c->mount_opts.unmount_mode == 1)
  		seq_printf(s, ",norm_unmount");

  	if (c->mount_opts.bulk_read == 2)
  		seq_printf(s, ",bulk_read");
  	else if (c->mount_opts.bulk_read == 1)
  		seq_printf(s, ",no_bulk_read");

  	if (c->mount_opts.chk_data_crc == 2)
  		seq_printf(s, ",chk_data_crc");
  	else if (c->mount_opts.chk_data_crc == 1)
  		seq_printf(s, ",no_chk_data_crc");

  	if (c->mount_opts.override_compr) {

  		seq_printf(s, ",compr=%s",
  			   ubifs_compr_name(c->mount_opts.compr_type));

  	}

  	return 0;
  }
  
  static int ubifs_sync_fs(struct super_block *sb, int wait)
  {

  	int i, err;

  	struct ubifs_info *c = sb->s_fs_info;

  	/*

  	 * Zero @wait is just an advisory thing to help the file system shove
  	 * lots of data into the queues, and there will be the second

  	 * '->sync_fs()' call, with non-zero @wait.
  	 */

  	if (!wait)
  		return 0;

  	/*

  	 * Synchronize write buffers, because 'ubifs_run_commit()' does not
  	 * do this if it waits for an already running commit.
  	 */
  	for (i = 0; i < c->jhead_cnt; i++) {
  		err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
  		if (err)
  			return err;
  	}

  	/*
  	 * Strictly speaking, it is not necessary to commit the journal here,
  	 * synchronizing write-buffers would be enough. But committing makes
  	 * UBIFS free space predictions much more accurate, so we want to let
  	 * the user be able to get more accurate results of 'statfs()' after
  	 * they synchronize the file system.
  	 */

  	err = ubifs_run_commit(c);
  	if (err)
  		return err;

  	return ubi_sync(c->vi.ubi_num);

  }
  
  /**
   * init_constants_early - initialize UBIFS constants.
   * @c: UBIFS file-system description object
   *
   * This function initialize UBIFS constants which do not need the superblock to
   * be read. It also checks that the UBI volume satisfies basic UBIFS
   * requirements. Returns zero in case of success and a negative error code in
   * case of failure.
   */
  static int init_constants_early(struct ubifs_info *c)
  {
  	if (c->vi.corrupted) {
  		ubifs_warn("UBI volume is corrupted - read-only mode");
  		c->ro_media = 1;
  	}
  
  	if (c->di.ro_mode) {
  		ubifs_msg("read-only UBI device");
  		c->ro_media = 1;
  	}
  
  	if (c->vi.vol_type == UBI_STATIC_VOLUME) {
  		ubifs_msg("static UBI volume - read-only mode");
  		c->ro_media = 1;
  	}
  
  	c->leb_cnt = c->vi.size;
  	c->leb_size = c->vi.usable_leb_size;

  	c->leb_start = c->di.leb_start;

  	c->half_leb_size = c->leb_size / 2;
  	c->min_io_size = c->di.min_io_size;
  	c->min_io_shift = fls(c->min_io_size) - 1;

  	c->max_write_size = c->di.max_write_size;
  	c->max_write_shift = fls(c->max_write_size) - 1;

  
  	if (c->leb_size < UBIFS_MIN_LEB_SZ) {
  		ubifs_err("too small LEBs (%d bytes), min. is %d bytes",
  			  c->leb_size, UBIFS_MIN_LEB_SZ);
  		return -EINVAL;
  	}
  
  	if (c->leb_cnt < UBIFS_MIN_LEB_CNT) {
  		ubifs_err("too few LEBs (%d), min. is %d",
  			  c->leb_cnt, UBIFS_MIN_LEB_CNT);
  		return -EINVAL;
  	}
  
  	if (!is_power_of_2(c->min_io_size)) {
  		ubifs_err("bad min. I/O size %d", c->min_io_size);
  		return -EINVAL;
  	}
  
  	/*

  	 * Maximum write size has to be greater or equivalent to min. I/O
  	 * size, and be multiple of min. I/O size.
  	 */
  	if (c->max_write_size < c->min_io_size ||
  	    c->max_write_size % c->min_io_size ||
  	    !is_power_of_2(c->max_write_size)) {
  		ubifs_err("bad write buffer size %d for %d min. I/O unit",
  			  c->max_write_size, c->min_io_size);
  		return -EINVAL;
  	}
  
  	/*

  	 * UBIFS aligns all node to 8-byte boundary, so to make function in
  	 * io.c simpler, assume minimum I/O unit size to be 8 bytes if it is
  	 * less than 8.
  	 */
  	if (c->min_io_size < 8) {
  		c->min_io_size = 8;
  		c->min_io_shift = 3;

  		if (c->max_write_size < c->min_io_size) {
  			c->max_write_size = c->min_io_size;
  			c->max_write_shift = c->min_io_shift;
  		}

  	}
  
  	c->ref_node_alsz = ALIGN(UBIFS_REF_NODE_SZ, c->min_io_size);
  	c->mst_node_alsz = ALIGN(UBIFS_MST_NODE_SZ, c->min_io_size);
  
  	/*
  	 * Initialize node length ranges which are mostly needed for node
  	 * length validation.
  	 */
  	c->ranges[UBIFS_PAD_NODE].len  = UBIFS_PAD_NODE_SZ;
  	c->ranges[UBIFS_SB_NODE].len   = UBIFS_SB_NODE_SZ;
  	c->ranges[UBIFS_MST_NODE].len  = UBIFS_MST_NODE_SZ;
  	c->ranges[UBIFS_REF_NODE].len  = UBIFS_REF_NODE_SZ;
  	c->ranges[UBIFS_TRUN_NODE].len = UBIFS_TRUN_NODE_SZ;
  	c->ranges[UBIFS_CS_NODE].len   = UBIFS_CS_NODE_SZ;
  
  	c->ranges[UBIFS_INO_NODE].min_len  = UBIFS_INO_NODE_SZ;
  	c->ranges[UBIFS_INO_NODE].max_len  = UBIFS_MAX_INO_NODE_SZ;
  	c->ranges[UBIFS_ORPH_NODE].min_len =
  				UBIFS_ORPH_NODE_SZ + sizeof(__le64);
  	c->ranges[UBIFS_ORPH_NODE].max_len = c->leb_size;
  	c->ranges[UBIFS_DENT_NODE].min_len = UBIFS_DENT_NODE_SZ;
  	c->ranges[UBIFS_DENT_NODE].max_len = UBIFS_MAX_DENT_NODE_SZ;
  	c->ranges[UBIFS_XENT_NODE].min_len = UBIFS_XENT_NODE_SZ;
  	c->ranges[UBIFS_XENT_NODE].max_len = UBIFS_MAX_XENT_NODE_SZ;
  	c->ranges[UBIFS_DATA_NODE].min_len = UBIFS_DATA_NODE_SZ;
  	c->ranges[UBIFS_DATA_NODE].max_len = UBIFS_MAX_DATA_NODE_SZ;
  	/*
  	 * Minimum indexing node size is amended later when superblock is
  	 * read and the key length is known.
  	 */
  	c->ranges[UBIFS_IDX_NODE].min_len = UBIFS_IDX_NODE_SZ + UBIFS_BRANCH_SZ;
  	/*
  	 * Maximum indexing node size is amended later when superblock is
  	 * read and the fanout is known.
  	 */
  	c->ranges[UBIFS_IDX_NODE].max_len = INT_MAX;
  
  	/*

  	 * Initialize dead and dark LEB space watermarks. See gc.c for comments
  	 * about these values.

  	 */
  	c->dead_wm = ALIGN(MIN_WRITE_SZ, c->min_io_size);
  	c->dark_wm = ALIGN(UBIFS_MAX_NODE_SZ, c->min_io_size);

  	/*
  	 * Calculate how many bytes would be wasted at the end of LEB if it was
  	 * fully filled with data nodes of maximum size. This is used in
  	 * calculations when reporting free space.
  	 */
  	c->leb_overhead = c->leb_size % UBIFS_MAX_DATA_NODE_SZ;

  	/* Buffer size for bulk-reads */

  	c->max_bu_buf_len = UBIFS_MAX_BULK_READ * UBIFS_MAX_DATA_NODE_SZ;
  	if (c->max_bu_buf_len > c->leb_size)
  		c->max_bu_buf_len = c->leb_size;

  	return 0;
  }
  
  /**
   * bud_wbuf_callback - bud LEB write-buffer synchronization call-back.
   * @c: UBIFS file-system description object
   * @lnum: LEB the write-buffer was synchronized to
   * @free: how many free bytes left in this LEB
   * @pad: how many bytes were padded
   *
   * This is a callback function which is called by the I/O unit when the
   * write-buffer is synchronized. We need this to correctly maintain space
   * accounting in bud logical eraseblocks. This function returns zero in case of
   * success and a negative error code in case of failure.
   *
   * This function actually belongs to the journal, but we keep it here because
   * we want to keep it static.
   */
  static int bud_wbuf_callback(struct ubifs_info *c, int lnum, int free, int pad)
  {
  	return ubifs_update_one_lp(c, lnum, free, pad, 0, 0);
  }
  
  /*

   * init_constants_sb - initialize UBIFS constants.

   * @c: UBIFS file-system description object
   *
   * This is a helper function which initializes various UBIFS constants after
   * the superblock has been read. It also checks various UBIFS parameters and
   * makes sure they are all right. Returns zero in case of success and a
   * negative error code in case of failure.
   */

  static int init_constants_sb(struct ubifs_info *c)

  {
  	int tmp, err;

  	long long tmp64;

  
  	c->main_bytes = (long long)c->main_lebs * c->leb_size;
  	c->max_znode_sz = sizeof(struct ubifs_znode) +
  				c->fanout * sizeof(struct ubifs_zbranch);
  
  	tmp = ubifs_idx_node_sz(c, 1);
  	c->ranges[UBIFS_IDX_NODE].min_len = tmp;
  	c->min_idx_node_sz = ALIGN(tmp, 8);
  
  	tmp = ubifs_idx_node_sz(c, c->fanout);
  	c->ranges[UBIFS_IDX_NODE].max_len = tmp;
  	c->max_idx_node_sz = ALIGN(tmp, 8);
  
  	/* Make sure LEB size is large enough to fit full commit */
  	tmp = UBIFS_CS_NODE_SZ + UBIFS_REF_NODE_SZ * c->jhead_cnt;
  	tmp = ALIGN(tmp, c->min_io_size);
  	if (tmp > c->leb_size) {
  		dbg_err("too small LEB size %d, at least %d needed",
  			c->leb_size, tmp);
  		return -EINVAL;
  	}
  
  	/*
  	 * Make sure that the log is large enough to fit reference nodes for
  	 * all buds plus one reserved LEB.
  	 */

  	tmp64 = c->max_bud_bytes + c->leb_size - 1;
  	c->max_bud_cnt = div_u64(tmp64, c->leb_size);

  	tmp = (c->ref_node_alsz * c->max_bud_cnt + c->leb_size - 1);
  	tmp /= c->leb_size;
  	tmp += 1;
  	if (c->log_lebs < tmp) {
  		dbg_err("too small log %d LEBs, required min. %d LEBs",
  			c->log_lebs, tmp);
  		return -EINVAL;
  	}
  
  	/*
  	 * When budgeting we assume worst-case scenarios when the pages are not
  	 * be compressed and direntries are of the maximum size.
  	 *
  	 * Note, data, which may be stored in inodes is budgeted separately, so

  	 * it is not included into 'c->bi.inode_budget'.

  	 */

  	c->bi.page_budget = UBIFS_MAX_DATA_NODE_SZ * UBIFS_BLOCKS_PER_PAGE;
  	c->bi.inode_budget = UBIFS_INO_NODE_SZ;
  	c->bi.dent_budget = UBIFS_MAX_DENT_NODE_SZ;

  
  	/*
  	 * When the amount of flash space used by buds becomes
  	 * 'c->max_bud_bytes', UBIFS just blocks all writers and starts commit.
  	 * The writers are unblocked when the commit is finished. To avoid
  	 * writers to be blocked UBIFS initiates background commit in advance,
  	 * when number of bud bytes becomes above the limit defined below.
  	 */
  	c->bg_bud_bytes = (c->max_bud_bytes * 13) >> 4;
  
  	/*
  	 * Ensure minimum journal size. All the bytes in the journal heads are
  	 * considered to be used, when calculating the current journal usage.
  	 * Consequently, if the journal is too small, UBIFS will treat it as
  	 * always full.
  	 */

  	tmp64 = (long long)(c->jhead_cnt + 1) * c->leb_size + 1;

  	if (c->bg_bud_bytes < tmp64)
  		c->bg_bud_bytes = tmp64;
  	if (c->max_bud_bytes < tmp64 + c->leb_size)
  		c->max_bud_bytes = tmp64 + c->leb_size;
  
  	err = ubifs_calc_lpt_geom(c);
  	if (err)
  		return err;

  	/* Initialize effective LEB size used in budgeting calculations */
  	c->idx_leb_size = c->leb_size - c->max_idx_node_sz;

  	return 0;
  }
  
  /*
   * init_constants_master - initialize UBIFS constants.
   * @c: UBIFS file-system description object
   *
   * This is a helper function which initializes various UBIFS constants after
   * the master node has been read. It also checks various UBIFS parameters and
   * makes sure they are all right.
   */
  static void init_constants_master(struct ubifs_info *c)
  {
  	long long tmp64;

  	c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c);

  	c->report_rp_size = ubifs_reported_space(c, c->rp_size);

  
  	/*
  	 * Calculate total amount of FS blocks. This number is not used
  	 * internally because it does not make much sense for UBIFS, but it is
  	 * necessary to report something for the 'statfs()' call.
  	 *

  	 * Subtract the LEB reserved for GC, the LEB which is reserved for

  	 * deletions, minimum LEBs for the index, and assume only one journal
  	 * head is available.

  	 */

  	tmp64 = c->main_lebs - 1 - 1 - MIN_INDEX_LEBS - c->jhead_cnt + 1;

  	tmp64 *= (long long)c->leb_size - c->leb_overhead;

  	tmp64 = ubifs_reported_space(c, tmp64);
  	c->block_cnt = tmp64 >> UBIFS_BLOCK_SHIFT;

  }
  
  /**
   * take_gc_lnum - reserve GC LEB.
   * @c: UBIFS file-system description object
   *

   * This function ensures that the LEB reserved for garbage collection is marked
   * as "taken" in lprops. We also have to set free space to LEB size and dirty
   * space to zero, because lprops may contain out-of-date information if the
   * file-system was un-mounted before it has been committed. This function
   * returns zero in case of success and a negative error code in case of
   * failure.

   */
  static int take_gc_lnum(struct ubifs_info *c)
  {
  	int err;
  
  	if (c->gc_lnum == -1) {
  		ubifs_err("no LEB for GC");
  		return -EINVAL;
  	}

  	/* And we have to tell lprops that this LEB is taken */
  	err = ubifs_change_one_lp(c, c->gc_lnum, c->leb_size, 0,
  				  LPROPS_TAKEN, 0, 0);
  	return err;
  }
  
  /**
   * alloc_wbufs - allocate write-buffers.
   * @c: UBIFS file-system description object
   *
   * This helper function allocates and initializes UBIFS write-buffers. Returns
   * zero in case of success and %-ENOMEM in case of failure.
   */
  static int alloc_wbufs(struct ubifs_info *c)
  {
  	int i, err;
  
  	c->jheads = kzalloc(c->jhead_cnt * sizeof(struct ubifs_jhead),
  			   GFP_KERNEL);
  	if (!c->jheads)
  		return -ENOMEM;
  
  	/* Initialize journal heads */
  	for (i = 0; i < c->jhead_cnt; i++) {
  		INIT_LIST_HEAD(&c->jheads[i].buds_list);
  		err = ubifs_wbuf_init(c, &c->jheads[i].wbuf);
  		if (err)
  			return err;
  
  		c->jheads[i].wbuf.sync_callback = &bud_wbuf_callback;
  		c->jheads[i].wbuf.jhead = i;

  		c->jheads[i].grouped = 1;

  	}
  
  	c->jheads[BASEHD].wbuf.dtype = UBI_SHORTTERM;
  	/*
  	 * Garbage Collector head likely contains long-term data and

  	 * does not need to be synchronized by timer. Also GC head nodes are
  	 * not grouped.

  	 */
  	c->jheads[GCHD].wbuf.dtype = UBI_LONGTERM;

  	c->jheads[GCHD].wbuf.no_timer = 1;

  	c->jheads[GCHD].grouped = 0;

  
  	return 0;
  }
  
  /**
   * free_wbufs - free write-buffers.
   * @c: UBIFS file-system description object
   */
  static void free_wbufs(struct ubifs_info *c)
  {
  	int i;
  
  	if (c->jheads) {
  		for (i = 0; i < c->jhead_cnt; i++) {
  			kfree(c->jheads[i].wbuf.buf);
  			kfree(c->jheads[i].wbuf.inodes);
  		}
  		kfree(c->jheads);
  		c->jheads = NULL;
  	}
  }
  
  /**
   * free_orphans - free orphans.
   * @c: UBIFS file-system description object
   */
  static void free_orphans(struct ubifs_info *c)
  {
  	struct ubifs_orphan *orph;
  
  	while (c->orph_dnext) {
  		orph = c->orph_dnext;
  		c->orph_dnext = orph->dnext;
  		list_del(&orph->list);
  		kfree(orph);
  	}
  
  	while (!list_empty(&c->orph_list)) {
  		orph = list_entry(c->orph_list.next, struct ubifs_orphan, list);
  		list_del(&orph->list);
  		kfree(orph);
  		dbg_err("orphan list not empty at unmount");
  	}
  
  	vfree(c->orph_buf);
  	c->orph_buf = NULL;
  }
  
  /**
   * free_buds - free per-bud objects.
   * @c: UBIFS file-system description object
   */
  static void free_buds(struct ubifs_info *c)
  {
  	struct rb_node *this = c->buds.rb_node;
  	struct ubifs_bud *bud;
  
  	while (this) {
  		if (this->rb_left)
  			this = this->rb_left;
  		else if (this->rb_right)
  			this = this->rb_right;
  		else {
  			bud = rb_entry(this, struct ubifs_bud, rb);
  			this = rb_parent(this);
  			if (this) {
  				if (this->rb_left == &bud->rb)
  					this->rb_left = NULL;
  				else
  					this->rb_right = NULL;
  			}
  			kfree(bud);
  		}
  	}
  }
  
  /**
   * check_volume_empty - check if the UBI volume is empty.
   * @c: UBIFS file-system description object
   *
   * This function checks if the UBIFS volume is empty by looking if its LEBs are
   * mapped or not. The result of checking is stored in the @c->empty variable.
   * Returns zero in case of success and a negative error code in case of
   * failure.
   */
  static int check_volume_empty(struct ubifs_info *c)
  {
  	int lnum, err;
  
  	c->empty = 1;
  	for (lnum = 0; lnum < c->leb_cnt; lnum++) {

  		err = ubifs_is_mapped(c, lnum);

  		if (unlikely(err < 0))
  			return err;
  		if (err == 1) {
  			c->empty = 0;
  			break;
  		}
  
  		cond_resched();
  	}
  
  	return 0;
  }
  
  /*
   * UBIFS mount options.
   *
   * Opt_fast_unmount: do not run a journal commit before un-mounting
   * Opt_norm_unmount: run a journal commit before un-mounting

   * Opt_bulk_read: enable bulk-reads
   * Opt_no_bulk_read: disable bulk-reads

   * Opt_chk_data_crc: check CRCs when reading data nodes
   * Opt_no_chk_data_crc: do not check CRCs when reading data nodes

   * Opt_override_compr: override default compressor

   * Opt_err: just end of array marker
   */
  enum {
  	Opt_fast_unmount,
  	Opt_norm_unmount,

  	Opt_bulk_read,
  	Opt_no_bulk_read,

  	Opt_chk_data_crc,
  	Opt_no_chk_data_crc,

  	Opt_override_compr,

  	Opt_err,
  };

  static const match_table_t tokens = {

  	{Opt_fast_unmount, "fast_unmount"},
  	{Opt_norm_unmount, "norm_unmount"},

  	{Opt_bulk_read, "bulk_read"},
  	{Opt_no_bulk_read, "no_bulk_read"},

  	{Opt_chk_data_crc, "chk_data_crc"},
  	{Opt_no_chk_data_crc, "no_chk_data_crc"},

  	{Opt_override_compr, "compr=%s"},

  	{Opt_err, NULL},
  };
  
  /**

   * parse_standard_option - parse a standard mount option.
   * @option: the option to parse
   *
   * Normally, standard mount options like "sync" are passed to file-systems as
   * flags. However, when a "rootflags=" kernel boot parameter is used, they may
   * be present in the options string. This function tries to deal with this
   * situation and parse standard options. Returns 0 if the option was not
   * recognized, and the corresponding integer flag if it was.
   *
   * UBIFS is only interested in the "sync" option, so do not check for anything
   * else.
   */
  static int parse_standard_option(const char *option)
  {
  	ubifs_msg("parse %s", option);
  	if (!strcmp(option, "sync"))
  		return MS_SYNCHRONOUS;
  	return 0;
  }
  
  /**

   * ubifs_parse_options - parse mount parameters.
   * @c: UBIFS file-system description object
   * @options: parameters to parse
   * @is_remount: non-zero if this is FS re-mount
   *
   * This function parses UBIFS mount options and returns zero in case success
   * and a negative error code in case of failure.
   */
  static int ubifs_parse_options(struct ubifs_info *c, char *options,
  			       int is_remount)
  {
  	char *p;
  	substring_t args[MAX_OPT_ARGS];
  
  	if (!options)
  		return 0;
  
  	while ((p = strsep(&options, ","))) {
  		int token;
  
  		if (!*p)
  			continue;
  
  		token = match_token(p, tokens, args);
  		switch (token) {

  		/*
  		 * %Opt_fast_unmount and %Opt_norm_unmount options are ignored.

  		 * We accept them in order to be backward-compatible. But this

  		 * should be removed at some point.
  		 */

  		case Opt_fast_unmount:
  			c->mount_opts.unmount_mode = 2;

  			break;
  		case Opt_norm_unmount:
  			c->mount_opts.unmount_mode = 1;

  			break;

  		case Opt_bulk_read:
  			c->mount_opts.bulk_read = 2;
  			c->bulk_read = 1;
  			break;
  		case Opt_no_bulk_read:
  			c->mount_opts.bulk_read = 1;
  			c->bulk_read = 0;
  			break;

  		case Opt_chk_data_crc:
  			c->mount_opts.chk_data_crc = 2;
  			c->no_chk_data_crc = 0;
  			break;
  		case Opt_no_chk_data_crc:
  			c->mount_opts.chk_data_crc = 1;
  			c->no_chk_data_crc = 1;
  			break;

  		case Opt_override_compr:
  		{
  			char *name = match_strdup(&args[0]);
  
  			if (!name)
  				return -ENOMEM;
  			if (!strcmp(name, "none"))
  				c->mount_opts.compr_type = UBIFS_COMPR_NONE;
  			else if (!strcmp(name, "lzo"))
  				c->mount_opts.compr_type = UBIFS_COMPR_LZO;
  			else if (!strcmp(name, "zlib"))
  				c->mount_opts.compr_type = UBIFS_COMPR_ZLIB;
  			else {
  				ubifs_err("unknown compressor \"%s\"", name);
  				kfree(name);
  				return -EINVAL;
  			}
  			kfree(name);
  			c->mount_opts.override_compr = 1;
  			c->default_compr = c->mount_opts.compr_type;
  			break;
  		}

  		default:

  		{
  			unsigned long flag;
  			struct super_block *sb = c->vfs_sb;
  
  			flag = parse_standard_option(p);
  			if (!flag) {
  				ubifs_err("unrecognized mount option \"%s\" "
  					  "or missing value", p);
  				return -EINVAL;
  			}
  			sb->s_flags |= flag;
  			break;
  		}

  		}
  	}
  
  	return 0;
  }
  
  /**
   * destroy_journal - destroy journal data structures.
   * @c: UBIFS file-system description object
   *
   * This function destroys journal data structures including those that may have
   * been created by recovery functions.
   */
  static void destroy_journal(struct ubifs_info *c)
  {
  	while (!list_empty(&c->unclean_leb_list)) {
  		struct ubifs_unclean_leb *ucleb;
  
  		ucleb = list_entry(c->unclean_leb_list.next,
  				   struct ubifs_unclean_leb, list);
  		list_del(&ucleb->list);
  		kfree(ucleb);
  	}
  	while (!list_empty(&c->old_buds)) {
  		struct ubifs_bud *bud;
  
  		bud = list_entry(c->old_buds.next, struct ubifs_bud, list);
  		list_del(&bud->list);
  		kfree(bud);
  	}
  	ubifs_destroy_idx_gc(c);
  	ubifs_destroy_size_tree(c);
  	ubifs_tnc_close(c);
  	free_buds(c);
  }
  
  /**

   * bu_init - initialize bulk-read information.
   * @c: UBIFS file-system description object
   */
  static void bu_init(struct ubifs_info *c)
  {
  	ubifs_assert(c->bulk_read == 1);
  
  	if (c->bu.buf)
  		return; /* Already initialized */
  
  again:
  	c->bu.buf = kmalloc(c->max_bu_buf_len, GFP_KERNEL | __GFP_NOWARN);
  	if (!c->bu.buf) {
  		if (c->max_bu_buf_len > UBIFS_KMALLOC_OK) {
  			c->max_bu_buf_len = UBIFS_KMALLOC_OK;
  			goto again;
  		}
  
  		/* Just disable bulk-read */
  		ubifs_warn("Cannot allocate %d bytes of memory for bulk-read, "
  			   "disabling it", c->max_bu_buf_len);
  		c->mount_opts.bulk_read = 1;
  		c->bulk_read = 0;
  		return;
  	}
  }
  
  /**

   * check_free_space - check if there is enough free space to mount.
   * @c: UBIFS file-system description object
   *
   * This function makes sure UBIFS has enough free space to be mounted in
   * read/write mode. UBIFS must always have some free space to allow deletions.
   */
  static int check_free_space(struct ubifs_info *c)
  {
  	ubifs_assert(c->dark_wm > 0);
  	if (c->lst.total_free + c->lst.total_dirty < c->dark_wm) {

  		ubifs_err("insufficient free space to mount in R/W mode");

  		dbg_dump_budg(c, &c->bi);

  		dbg_dump_lprops(c);

  		return -ENOSPC;

  	}
  	return 0;
  }
  
  /**

   * mount_ubifs - mount UBIFS file-system.
   * @c: UBIFS file-system description object
   *
   * This function mounts UBIFS file system. Returns zero in case of success and
   * a negative error code in case of failure.
   *
   * Note, the function does not de-allocate resources it it fails half way
   * through, and the caller has to do this instead.
   */
  static int mount_ubifs(struct ubifs_info *c)
  {

  	int err;

  	long long x;
  	size_t sz;

  	c->ro_mount = !!(c->vfs_sb->s_flags & MS_RDONLY);

  	err = init_constants_early(c);
  	if (err)
  		return err;

  	err = ubifs_debugging_init(c);
  	if (err)
  		return err;

  
  	err = check_volume_empty(c);
  	if (err)
  		goto out_free;

  	if (c->empty && (c->ro_mount || c->ro_media)) {

  		/*
  		 * This UBI volume is empty, and read-only, or the file system
  		 * is mounted read-only - we cannot format it.
  		 */
  		ubifs_err("can't format empty UBI volume: read-only %s",
  			  c->ro_media ? "UBI volume" : "mount");
  		err = -EROFS;
  		goto out_free;
  	}

  	if (c->ro_media && !c->ro_mount) {

  		ubifs_err("cannot mount read-write - read-only media");
  		err = -EROFS;
  		goto out_free;
  	}
  
  	/*
  	 * The requirement for the buffer is that it should fit indexing B-tree
  	 * height amount of integers. We assume the height if the TNC tree will
  	 * never exceed 64.
  	 */
  	err = -ENOMEM;
  	c->bottom_up_buf = kmalloc(BOTTOM_UP_HEIGHT * sizeof(int), GFP_KERNEL);
  	if (!c->bottom_up_buf)
  		goto out_free;
  
  	c->sbuf = vmalloc(c->leb_size);
  	if (!c->sbuf)
  		goto out_free;

  	if (!c->ro_mount) {

  		c->ileb_buf = vmalloc(c->leb_size);
  		if (!c->ileb_buf)
  			goto out_free;
  	}

  	if (c->bulk_read == 1)
  		bu_init(c);

  	if (!c->ro_mount) {
  		c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ,
  					       GFP_KERNEL);
  		if (!c->write_reserve_buf)
  			goto out_free;
  	}

  	c->mounting = 1;

  	err = ubifs_read_superblock(c);
  	if (err)
  		goto out_free;
  
  	/*

  	 * Make sure the compressor which is set as default in the superblock

  	 * or overridden by mount options is actually compiled in.

  	 */
  	if (!ubifs_compr_present(c->default_compr)) {

  		ubifs_err("'compressor \"%s\" is not compiled in",
  			  ubifs_compr_name(c->default_compr));

  		err = -ENOTSUPP;

  		goto out_free;

  	}

  	err = init_constants_sb(c);

  	if (err)

  		goto out_free;

  
  	sz = ALIGN(c->max_idx_node_sz, c->min_io_size);
  	sz = ALIGN(sz + c->max_idx_node_sz, c->min_io_size);
  	c->cbuf = kmalloc(sz, GFP_NOFS);
  	if (!c->cbuf) {
  		err = -ENOMEM;

  		goto out_free;

  	}

  	err = alloc_wbufs(c);
  	if (err)
  		goto out_cbuf;

  	sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num, c->vi.vol_id);

  	if (!c->ro_mount) {

  		/* Create background thread */

  		c->bgt = kthread_create(ubifs_bg_thread, c, "%s", c->bgt_name);

  		if (IS_ERR(c->bgt)) {
  			err = PTR_ERR(c->bgt);
  			c->bgt = NULL;
  			ubifs_err("cannot spawn \"%s\", error %d",
  				  c->bgt_name, err);
  			goto out_wbufs;
  		}
  		wake_up_process(c->bgt);
  	}
  
  	err = ubifs_read_master(c);
  	if (err)
  		goto out_master;

  	init_constants_master(c);

  	if ((c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY)) != 0) {
  		ubifs_msg("recovery needed");
  		c->need_recovery = 1;

  	}

  	if (c->need_recovery && !c->ro_mount) {
  		err = ubifs_recover_inl_heads(c, c->sbuf);
  		if (err)
  			goto out_master;
  	}
  
  	err = ubifs_lpt_init(c, 1, !c->ro_mount);
  	if (err)
  		goto out_master;

  	if (!c->ro_mount && c->space_fixup) {
  		err = ubifs_fixup_free_space(c);
  		if (err)
  			goto out_master;
  	}

  	if (!c->ro_mount) {

  		/*
  		 * Set the "dirty" flag so that if we reboot uncleanly we
  		 * will notice this immediately on the next mount.
  		 */
  		c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
  		err = ubifs_write_master(c);
  		if (err)

  			goto out_lpt;

  	}

  	err = dbg_check_idx_size(c, c->bi.old_idx_sz);

  	if (err)
  		goto out_lpt;
  
  	err = ubifs_replay_journal(c);
  	if (err)
  		goto out_journal;

  	/* Calculate 'min_idx_lebs' after journal replay */

  	c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c);

  	err = ubifs_mount_orphans(c, c->need_recovery, c->ro_mount);

  	if (err)
  		goto out_orphans;

  	if (!c->ro_mount) {

  		int lnum;

  		err = check_free_space(c);
  		if (err)

  			goto out_orphans;

  
  		/* Check for enough log space */
  		lnum = c->lhead_lnum + 1;
  		if (lnum >= UBIFS_LOG_LNUM + c->log_lebs)
  			lnum = UBIFS_LOG_LNUM;
  		if (lnum == c->ltail_lnum) {
  			err = ubifs_consolidate_log(c);
  			if (err)
  				goto out_orphans;
  		}
  
  		if (c->need_recovery) {
  			err = ubifs_recover_size(c);
  			if (err)
  				goto out_orphans;
  			err = ubifs_rcvry_gc_commit(c);

  			if (err)
  				goto out_orphans;

  		} else {

  			err = take_gc_lnum(c);

  			if (err)
  				goto out_orphans;
  
  			/*
  			 * GC LEB may contain garbage if there was an unclean
  			 * reboot, and it should be un-mapped.
  			 */
  			err = ubifs_leb_unmap(c, c->gc_lnum);
  			if (err)

  				goto out_orphans;

  		}

  
  		err = dbg_check_lprops(c);
  		if (err)
  			goto out_orphans;
  	} else if (c->need_recovery) {
  		err = ubifs_recover_size(c);
  		if (err)
  			goto out_orphans;

  	} else {
  		/*
  		 * Even if we mount read-only, we have to set space in GC LEB
  		 * to proper value because this affects UBIFS free space
  		 * reporting. We do not want to have a situation when
  		 * re-mounting from R/O to R/W changes amount of free space.
  		 */
  		err = take_gc_lnum(c);
  		if (err)
  			goto out_orphans;

  	}
  
  	spin_lock(&ubifs_infos_lock);
  	list_add_tail(&c->infos_list, &ubifs_infos);
  	spin_unlock(&ubifs_infos_lock);
  
  	if (c->need_recovery) {

  		if (c->ro_mount)

  			ubifs_msg("recovery deferred");
  		else {
  			c->need_recovery = 0;
  			ubifs_msg("recovery completed");

  			/*
  			 * GC LEB has to be empty and taken at this point. But
  			 * the journal head LEBs may also be accounted as
  			 * "empty taken" if they are empty.
  			 */
  			ubifs_assert(c->lst.taken_empty_lebs > 0);

  		}

  	} else

  		ubifs_assert(c->lst.taken_empty_lebs > 0);

  	err = dbg_check_filesystem(c);

  	if (err)
  		goto out_infos;

  	err = dbg_debugfs_init_fs(c);

  	if (err)
  		goto out_infos;

  	c->mounting = 0;

  	ubifs_msg("mounted UBI device %d, volume %d, name \"%s\"",
  		  c->vi.ubi_num, c->vi.vol_id, c->vi.name);

  	if (c->ro_mount)

  		ubifs_msg("mounted read-only");
  	x = (long long)c->main_lebs * c->leb_size;

  	ubifs_msg("file system size:   %lld bytes (%lld KiB, %lld MiB, %d "
  		  "LEBs)", x, x >> 10, x >> 20, c->main_lebs);

  	x = (long long)c->log_lebs * c->leb_size + c->max_bud_bytes;

  	ubifs_msg("journal size:       %lld bytes (%lld KiB, %lld MiB, %d "
  		  "LEBs)", x, x >> 10, x >> 20, c->log_lebs + c->max_bud_cnt);

  	ubifs_msg("media format:       w%d/r%d (latest is w%d/r%d)",
  		  c->fmt_version, c->ro_compat_version,
  		  UBIFS_FORMAT_VERSION, UBIFS_RO_COMPAT_VERSION);

  	ubifs_msg("default compressor: %s", ubifs_compr_name(c->default_compr));

  	ubifs_msg("reserved for root:  %llu bytes (%llu KiB)",

  		c->report_rp_size, c->report_rp_size >> 10);

  
  	dbg_msg("compiled on:         " __DATE__ " at " __TIME__);
  	dbg_msg("min. I/O unit size:  %d bytes", c->min_io_size);

  	dbg_msg("max. write size:     %d bytes", c->max_write_size);

  	dbg_msg("LEB size:            %d bytes (%d KiB)",

  		c->leb_size, c->leb_size >> 10);

  	dbg_msg("data journal heads:  %d",
  		c->jhead_cnt - NONDATA_JHEADS_CNT);

  	dbg_msg("UUID:                %pUB", c->uuid);

  	dbg_msg("big_lpt              %d", c->big_lpt);
  	dbg_msg("log LEBs:            %d (%d - %d)",
  		c->log_lebs, UBIFS_LOG_LNUM, c->log_last);
  	dbg_msg("LPT area LEBs:       %d (%d - %d)",
  		c->lpt_lebs, c->lpt_first, c->lpt_last);
  	dbg_msg("orphan area LEBs:    %d (%d - %d)",
  		c->orph_lebs, c->orph_first, c->orph_last);
  	dbg_msg("main area LEBs:      %d (%d - %d)",
  		c->main_lebs, c->main_first, c->leb_cnt - 1);
  	dbg_msg("index LEBs:          %d", c->lst.idx_lebs);
  	dbg_msg("total index bytes:   %lld (%lld KiB, %lld MiB)",

  		c->bi.old_idx_sz, c->bi.old_idx_sz >> 10,
  		c->bi.old_idx_sz >> 20);

  	dbg_msg("key hash type:       %d", c->key_hash_type);
  	dbg_msg("tree fanout:         %d", c->fanout);
  	dbg_msg("reserved GC LEB:     %d", c->gc_lnum);
  	dbg_msg("first main LEB:      %d", c->main_first);

  	dbg_msg("max. znode size      %d", c->max_znode_sz);
  	dbg_msg("max. index node size %d", c->max_idx_node_sz);
  	dbg_msg("node sizes:          data %zu, inode %zu, dentry %zu",
  		UBIFS_DATA_NODE_SZ, UBIFS_INO_NODE_SZ, UBIFS_DENT_NODE_SZ);
  	dbg_msg("node sizes:          trun %zu, sb %zu, master %zu",
  		UBIFS_TRUN_NODE_SZ, UBIFS_SB_NODE_SZ, UBIFS_MST_NODE_SZ);
  	dbg_msg("node sizes:          ref %zu, cmt. start %zu, orph %zu",
  		UBIFS_REF_NODE_SZ, UBIFS_CS_NODE_SZ, UBIFS_ORPH_NODE_SZ);

  	dbg_msg("max. node sizes:     data %zu, inode %zu dentry %zu, idx %d",

  		UBIFS_MAX_DATA_NODE_SZ, UBIFS_MAX_INO_NODE_SZ,

  		UBIFS_MAX_DENT_NODE_SZ, ubifs_idx_node_sz(c, c->fanout));

  	dbg_msg("dead watermark:      %d", c->dead_wm);
  	dbg_msg("dark watermark:      %d", c->dark_wm);

  	dbg_msg("LEB overhead:        %d", c->leb_overhead);

  	x = (long long)c->main_lebs * c->dark_wm;
  	dbg_msg("max. dark space:     %lld (%lld KiB, %lld MiB)",
  		x, x >> 10, x >> 20);
  	dbg_msg("maximum bud bytes:   %lld (%lld KiB, %lld MiB)",
  		c->max_bud_bytes, c->max_bud_bytes >> 10,
  		c->max_bud_bytes >> 20);
  	dbg_msg("BG commit bud bytes: %lld (%lld KiB, %lld MiB)",
  		c->bg_bud_bytes, c->bg_bud_bytes >> 10,
  		c->bg_bud_bytes >> 20);
  	dbg_msg("current bud bytes    %lld (%lld KiB, %lld MiB)",
  		c->bud_bytes, c->bud_bytes >> 10, c->bud_bytes >> 20);
  	dbg_msg("max. seq. number:    %llu", c->max_sqnum);
  	dbg_msg("commit number:       %llu", c->cmt_no);
  
  	return 0;
  
  out_infos:
  	spin_lock(&ubifs_infos_lock);
  	list_del(&c->infos_list);
  	spin_unlock(&ubifs_infos_lock);
  out_orphans:
  	free_orphans(c);
  out_journal:
  	destroy_journal(c);
  out_lpt:
  	ubifs_lpt_free(c, 0);
  out_master:
  	kfree(c->mst_node);
  	kfree(c->rcvrd_mst_node);
  	if (c->bgt)
  		kthread_stop(c->bgt);
  out_wbufs:
  	free_wbufs(c);
  out_cbuf:
  	kfree(c->cbuf);

  out_free:

  	kfree(c->write_reserve_buf);

  	kfree(c->bu.buf);

  	vfree(c->ileb_buf);
  	vfree(c->sbuf);
  	kfree(c->bottom_up_buf);

  	ubifs_debugging_exit(c);

  	return err;
  }
  
  /**
   * ubifs_umount - un-mount UBIFS file-system.
   * @c: UBIFS file-system description object
   *
   * Note, this function is called to free allocated resourced when un-mounting,
   * as well as free resources when an error occurred while we were half way
   * through mounting (error path cleanup function). So it has to make sure the
   * resource was actually allocated before freeing it.
   */
  static void ubifs_umount(struct ubifs_info *c)
  {
  	dbg_gen("un-mounting UBI device %d, volume %d", c->vi.ubi_num,
  		c->vi.vol_id);

  	dbg_debugfs_exit_fs(c);

  	spin_lock(&ubifs_infos_lock);
  	list_del(&c->infos_list);
  	spin_unlock(&ubifs_infos_lock);
  
  	if (c->bgt)
  		kthread_stop(c->bgt);
  
  	destroy_journal(c);
  	free_wbufs(c);
  	free_orphans(c);
  	ubifs_lpt_free(c, 0);
  
  	kfree(c->cbuf);
  	kfree(c->rcvrd_mst_node);
  	kfree(c->mst_node);

  	kfree(c->write_reserve_buf);

  	kfree(c->bu.buf);
  	vfree(c->ileb_buf);

  	vfree(c->sbuf);
  	kfree(c->bottom_up_buf);

  	ubifs_debugging_exit(c);

  }
  
  /**
   * ubifs_remount_rw - re-mount in read-write mode.
   * @c: UBIFS file-system description object
   *
   * UBIFS avoids allocating many unnecessary resources when mounted in read-only
   * mode. This function allocates the needed resources and re-mounts UBIFS in
   * read-write mode.
   */
  static int ubifs_remount_rw(struct ubifs_info *c)
  {
  	int err, lnum;

  	if (c->rw_incompat) {
  		ubifs_err("the file-system is not R/W-compatible");
  		ubifs_msg("on-flash format version is w%d/r%d, but software "
  			  "only supports up to version w%d/r%d", c->fmt_version,
  			  c->ro_compat_version, UBIFS_FORMAT_VERSION,
  			  UBIFS_RO_COMPAT_VERSION);
  		return -EROFS;
  	}

  	mutex_lock(&c->umount_mutex);

  	dbg_save_space_info(c);

  	c->remounting_rw = 1;

  	c->ro_mount = 0;

  	err = check_free_space(c);
  	if (err)

  		goto out;

  
  	if (c->old_leb_cnt != c->leb_cnt) {
  		struct ubifs_sb_node *sup;
  
  		sup = ubifs_read_sb_node(c);
  		if (IS_ERR(sup)) {
  			err = PTR_ERR(sup);
  			goto out;
  		}
  		sup->leb_cnt = cpu_to_le32(c->leb_cnt);
  		err = ubifs_write_sb_node(c, sup);

  		kfree(sup);

  		if (err)
  			goto out;
  	}
  
  	if (c->need_recovery) {
  		ubifs_msg("completing deferred recovery");
  		err = ubifs_write_rcvrd_mst_node(c);
  		if (err)
  			goto out;
  		err = ubifs_recover_size(c);
  		if (err)
  			goto out;
  		err = ubifs_clean_lebs(c, c->sbuf);
  		if (err)
  			goto out;
  		err = ubifs_recover_inl_heads(c, c->sbuf);
  		if (err)
  			goto out;

  	} else {
  		/* A readonly mount is not allowed to have orphans */
  		ubifs_assert(c->tot_orphans == 0);
  		err = ubifs_clear_orphans(c);
  		if (err)
  			goto out;

  	}
  
  	if (!(c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY))) {
  		c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
  		err = ubifs_write_master(c);
  		if (err)
  			goto out;
  	}
  
  	c->ileb_buf = vmalloc(c->leb_size);
  	if (!c->ileb_buf) {
  		err = -ENOMEM;
  		goto out;
  	}

  	c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ, GFP_KERNEL);
  	if (!c->write_reserve_buf)
  		goto out;

  	err = ubifs_lpt_init(c, 0, 1);
  	if (err)
  		goto out;

  	/* Create background thread */

  	c->bgt = kthread_create(ubifs_bg_thread, c, "%s", c->bgt_name);

  	if (IS_ERR(c->bgt)) {
  		err = PTR_ERR(c->bgt);
  		c->bgt = NULL;
  		ubifs_err("cannot spawn \"%s\", error %d",
  			  c->bgt_name, err);

  		goto out;

  	}
  	wake_up_process(c->bgt);
  
  	c->orph_buf = vmalloc(c->leb_size);

  	if (!c->orph_buf) {
  		err = -ENOMEM;
  		goto out;
  	}

  
  	/* Check for enough log space */
  	lnum = c->lhead_lnum + 1;
  	if (lnum >= UBIFS_LOG_LNUM + c->log_lebs)
  		lnum = UBIFS_LOG_LNUM;
  	if (lnum == c->ltail_lnum) {
  		err = ubifs_consolidate_log(c);
  		if (err)
  			goto out;
  	}
  
  	if (c->need_recovery)
  		err = ubifs_rcvry_gc_commit(c);
  	else

  		err = ubifs_leb_unmap(c, c->gc_lnum);

  	if (err)
  		goto out;

  	dbg_gen("re-mounted read-write");
  	c->remounting_rw = 0;

  	if (c->need_recovery) {
  		c->need_recovery = 0;
  		ubifs_msg("deferred recovery completed");

  	} else {
  		/*
  		 * Do not run the debugging space check if the were doing
  		 * recovery, because when we saved the information we had the
  		 * file-system in a state where the TNC and lprops has been
  		 * modified in memory, but all the I/O operations (including a
  		 * commit) were deferred. So the file-system was in
  		 * "non-committed" state. Now the file-system is in committed
  		 * state, and of course the amount of free space will change
  		 * because, for example, the old index size was imprecise.
  		 */
  		err = dbg_check_space_info(c);

  	}

  
  	if (c->space_fixup) {
  		err = ubifs_fixup_free_space(c);
  		if (err)
  			goto out;
  	}

  	mutex_unlock(&c->umount_mutex);

  	return err;

  
  out:

  	c->ro_mount = 1;

  	vfree(c->orph_buf);
  	c->orph_buf = NULL;
  	if (c->bgt) {
  		kthread_stop(c->bgt);
  		c->bgt = NULL;
  	}
  	free_wbufs(c);

  	kfree(c->write_reserve_buf);
  	c->write_reserve_buf = NULL;

  	vfree(c->ileb_buf);
  	c->ileb_buf = NULL;
  	ubifs_lpt_free(c, 1);
  	c->remounting_rw = 0;
  	mutex_unlock(&c->umount_mutex);
  	return err;
  }
  
  /**

   * ubifs_remount_ro - re-mount in read-only mode.
   * @c: UBIFS file-system description object
   *

   * We assume VFS has stopped writing. Possibly the background thread could be
   * running a commit, however kthread_stop will wait in that case.

   */
  static void ubifs_remount_ro(struct ubifs_info *c)
  {
  	int i, err;
  
  	ubifs_assert(!c->need_recovery);

  	ubifs_assert(!c->ro_mount);

  	mutex_lock(&c->umount_mutex);
  	if (c->bgt) {
  		kthread_stop(c->bgt);
  		c->bgt = NULL;
  	}

  	dbg_save_space_info(c);

  	for (i = 0; i < c->jhead_cnt; i++)

  		ubifs_wbuf_sync(&c->jheads[i].wbuf);

  	c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
  	c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
  	c->mst_node->gc_lnum = cpu_to_le32(c->gc_lnum);
  	err = ubifs_write_master(c);
  	if (err)
  		ubifs_ro_mode(c, err);

  	vfree(c->orph_buf);
  	c->orph_buf = NULL;

  	kfree(c->write_reserve_buf);
  	c->write_reserve_buf = NULL;

  	vfree(c->ileb_buf);
  	c->ileb_buf = NULL;
  	ubifs_lpt_free(c, 1);

  	c->ro_mount = 1;

  	err = dbg_check_space_info(c);
  	if (err)
  		ubifs_ro_mode(c, err);

  	mutex_unlock(&c->umount_mutex);
  }
  
  static void ubifs_put_super(struct super_block *sb)
  {
  	int i;
  	struct ubifs_info *c = sb->s_fs_info;
  
  	ubifs_msg("un-mount UBI device %d, volume %d", c->vi.ubi_num,
  		  c->vi.vol_id);

  	/*
  	 * The following asserts are only valid if there has not been a failure
  	 * of the media. For example, there will be dirty inodes if we failed
  	 * to write them back because of I/O errors.
  	 */

  	if (!c->ro_error) {

  		ubifs_assert(c->bi.idx_growth == 0);
  		ubifs_assert(c->bi.dd_growth == 0);
  		ubifs_assert(c->bi.data_growth == 0);

  	}

  
  	/*
  	 * The 'c->umount_lock' prevents races between UBIFS memory shrinker
  	 * and file system un-mount. Namely, it prevents the shrinker from
  	 * picking this superblock for shrinking - it will be just skipped if
  	 * the mutex is locked.
  	 */
  	mutex_lock(&c->umount_mutex);

  	if (!c->ro_mount) {

  		/*
  		 * First of all kill the background thread to make sure it does
  		 * not interfere with un-mounting and freeing resources.
  		 */
  		if (c->bgt) {
  			kthread_stop(c->bgt);
  			c->bgt = NULL;
  		}

  		/*

  		 * On fatal errors c->ro_error is set to 1, in which case we do

  		 * not write the master node.
  		 */

  		if (!c->ro_error) {

  			int err;
  
  			/* Synchronize write-buffers */

  			for (i = 0; i < c->jhead_cnt; i++)
  				ubifs_wbuf_sync(&c->jheads[i].wbuf);

  			/*
  			 * We are being cleanly unmounted which means the
  			 * orphans were killed - indicate this in the master
  			 * node. Also save the reserved GC LEB number.
  			 */

  			c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
  			c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
  			c->mst_node->gc_lnum = cpu_to_le32(c->gc_lnum);
  			err = ubifs_write_master(c);
  			if (err)
  				/*
  				 * Recovery will attempt to fix the master area
  				 * next mount, so we just print a message and
  				 * continue to unmount normally.
  				 */
  				ubifs_err("failed to write master node, "
  					  "error %d", err);

  		} else {
  			for (i = 0; i < c->jhead_cnt; i++)
  				/* Make sure write-buffer timers are canceled */
  				hrtimer_cancel(&c->jheads[i].wbuf.timer);

  		}
  	}
  
  	ubifs_umount(c);
  	bdi_destroy(&c->bdi);
  	ubi_close_volume(c->ubi);
  	mutex_unlock(&c->umount_mutex);

  }
  
  static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
  {
  	int err;
  	struct ubifs_info *c = sb->s_fs_info;
  
  	dbg_gen("old flags %#lx, new flags %#x", sb->s_flags, *flags);
  
  	err = ubifs_parse_options(c, data, 1);
  	if (err) {
  		ubifs_err("invalid or unknown remount parameter");
  		return err;
  	}

  	if (c->ro_mount && !(*flags & MS_RDONLY)) {

  		if (c->ro_error) {
  			ubifs_msg("cannot re-mount R/W due to prior errors");
  			return -EROFS;
  		}

  		if (c->ro_media) {

  			ubifs_msg("cannot re-mount R/W - UBI volume is R/O");

  			return -EROFS;

  		}

  		err = ubifs_remount_rw(c);

  		if (err)

  			return err;

  	} else if (!c->ro_mount && (*flags & MS_RDONLY)) {

  		if (c->ro_error) {
  			ubifs_msg("cannot re-mount R/O due to prior errors");

  			return -EROFS;

  		}

  		ubifs_remount_ro(c);

  	}

  	if (c->bulk_read == 1)
  		bu_init(c);
  	else {
  		dbg_gen("disable bulk-read");
  		kfree(c->bu.buf);
  		c->bu.buf = NULL;
  	}

  	ubifs_assert(c->lst.taken_empty_lebs > 0);

  	return 0;
  }

  const struct super_operations ubifs_super_operations = {

  	.alloc_inode   = ubifs_alloc_inode,
  	.destroy_inode = ubifs_destroy_inode,
  	.put_super     = ubifs_put_super,
  	.write_inode   = ubifs_write_inode,

  	.evict_inode   = ubifs_evict_inode,

  	.statfs        = ubifs_statfs,
  	.dirty_inode   = ubifs_dirty_inode,
  	.remount_fs    = ubifs_remount_fs,
  	.show_options  = ubifs_show_options,
  	.sync_fs       = ubifs_sync_fs,
  };
  
  /**
   * open_ubi - parse UBI device name string and open the UBI device.
   * @name: UBI volume name
   * @mode: UBI volume open mode
   *

   * The primary method of mounting UBIFS is by specifying the UBI volume
   * character device node path. However, UBIFS may also be mounted withoug any
   * character device node using one of the following methods:
   *
   * o ubiX_Y    - mount UBI device number X, volume Y;
   * o ubiY      - mount UBI device number 0, volume Y;

   * o ubiX:NAME - mount UBI device X, volume with name NAME;
   * o ubi:NAME  - mount UBI device 0, volume with name NAME.
   *
   * Alternative '!' separator may be used instead of ':' (because some shells
   * like busybox may interpret ':' as an NFS host name separator). This function

   * returns UBI volume description object in case of success and a negative
   * error code in case of failure.

   */
  static struct ubi_volume_desc *open_ubi(const char *name, int mode)
  {

  	struct ubi_volume_desc *ubi;

  	int dev, vol;
  	char *endptr;

  	/* First, try to open using the device node path method */
  	ubi = ubi_open_volume_path(name, mode);
  	if (!IS_ERR(ubi))
  		return ubi;
  
  	/* Try the "nodev" method */

  	if (name[0] != 'u' || name[1] != 'b' || name[2] != 'i')
  		return ERR_PTR(-EINVAL);
  
  	/* ubi:NAME method */
  	if ((name[3] == ':' || name[3] == '!') && name[4] != '\0')
  		return ubi_open_volume_nm(0, name + 4, mode);
  
  	if (!isdigit(name[3]))
  		return ERR_PTR(-EINVAL);
  
  	dev = simple_strtoul(name + 3, &endptr, 0);
  
  	/* ubiY method */
  	if (*endptr == '\0')
  		return ubi_open_volume(0, dev, mode);
  
  	/* ubiX_Y method */
  	if (*endptr == '_' && isdigit(endptr[1])) {
  		vol = simple_strtoul(endptr + 1, &endptr, 0);
  		if (*endptr != '\0')
  			return ERR_PTR(-EINVAL);
  		return ubi_open_volume(dev, vol, mode);
  	}
  
  	/* ubiX:NAME method */
  	if ((*endptr == ':' || *endptr == '!') && endptr[1] != '\0')
  		return ubi_open_volume_nm(dev, ++endptr, mode);
  
  	return ERR_PTR(-EINVAL);
  }

  static struct ubifs_info *alloc_ubifs_info(struct ubi_volume_desc *ubi)
  {
  	struct ubifs_info *c;
  
  	c = kzalloc(sizeof(struct ubifs_info), GFP_KERNEL);
  	if (c) {
  		spin_lock_init(&c->cnt_lock);
  		spin_lock_init(&c->cs_lock);
  		spin_lock_init(&c->buds_lock);
  		spin_lock_init(&c->space_lock);
  		spin_lock_init(&c->orphan_lock);
  		init_rwsem(&c->commit_sem);
  		mutex_init(&c->lp_mutex);
  		mutex_init(&c->tnc_mutex);
  		mutex_init(&c->log_mutex);
  		mutex_init(&c->mst_mutex);
  		mutex_init(&c->umount_mutex);
  		mutex_init(&c->bu_mutex);
  		mutex_init(&c->write_reserve_mutex);
  		init_waitqueue_head(&c->cmt_wq);
  		c->buds = RB_ROOT;
  		c->old_idx = RB_ROOT;
  		c->size_tree = RB_ROOT;
  		c->orph_tree = RB_ROOT;
  		INIT_LIST_HEAD(&c->infos_list);
  		INIT_LIST_HEAD(&c->idx_gc);
  		INIT_LIST_HEAD(&c->replay_list);
  		INIT_LIST_HEAD(&c->replay_buds);
  		INIT_LIST_HEAD(&c->uncat_list);
  		INIT_LIST_HEAD(&c->empty_list);
  		INIT_LIST_HEAD(&c->freeable_list);
  		INIT_LIST_HEAD(&c->frdi_idx_list);
  		INIT_LIST_HEAD(&c->unclean_leb_list);
  		INIT_LIST_HEAD(&c->old_buds);
  		INIT_LIST_HEAD(&c->orph_list);
  		INIT_LIST_HEAD(&c->orph_new);
  		c->no_chk_data_crc = 1;
  
  		c->highest_inum = UBIFS_FIRST_INO;
  		c->lhead_lnum = c->ltail_lnum = UBIFS_LOG_LNUM;
  
  		ubi_get_volume_info(ubi, &c->vi);
  		ubi_get_device_info(c->vi.ubi_num, &c->di);
  	}
  	return c;
  }

  static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
  {

  	struct ubifs_info *c = sb->s_fs_info;

  	struct inode *root;
  	int err;

  	c->vfs_sb = sb;

  	/* Re-open the UBI device in read-write mode */
  	c->ubi = ubi_open_volume(c->vi.ubi_num, c->vi.vol_id, UBI_READWRITE);
  	if (IS_ERR(c->ubi)) {
  		err = PTR_ERR(c->ubi);

  		goto out;

  	}
  
  	/*

  	 * UBIFS provides 'backing_dev_info' in order to disable read-ahead. For

  	 * UBIFS, I/O is not deferred, it is done immediately in readpage,
  	 * which means the user would have to wait not just for their own I/O

  	 * but the read-ahead I/O as well i.e. completely pointless.

  	 *
  	 * Read-ahead will be disabled because @c->bdi.ra_pages is 0.
  	 */

  	c->bdi.name = "ubifs",

  	c->bdi.capabilities = BDI_CAP_MAP_COPY;

  	err  = bdi_init(&c->bdi);
  	if (err)
  		goto out_close;

  	err = bdi_register(&c->bdi, NULL, "ubifs_%d_%d",
  			   c->vi.ubi_num, c->vi.vol_id);

  	if (err)
  		goto out_bdi;

  
  	err = ubifs_parse_options(c, data, 0);
  	if (err)
  		goto out_bdi;

  	sb->s_bdi = &c->bdi;

  	sb->s_fs_info = c;
  	sb->s_magic = UBIFS_SUPER_MAGIC;
  	sb->s_blocksize = UBIFS_BLOCK_SIZE;
  	sb->s_blocksize_bits = UBIFS_BLOCK_SHIFT;

  	sb->s_maxbytes = c->max_inode_sz = key_max_inode_size(c);
  	if (c->max_inode_sz > MAX_LFS_FILESIZE)
  		sb->s_maxbytes = c->max_inode_sz = MAX_LFS_FILESIZE;
  	sb->s_op = &ubifs_super_operations;
  
  	mutex_lock(&c->umount_mutex);
  	err = mount_ubifs(c);
  	if (err) {
  		ubifs_assert(err < 0);
  		goto out_unlock;
  	}
  
  	/* Read the root inode */
  	root = ubifs_iget(sb, UBIFS_ROOT_INO);
  	if (IS_ERR(root)) {
  		err = PTR_ERR(root);
  		goto out_umount;
  	}
  
  	sb->s_root = d_alloc_root(root);
  	if (!sb->s_root)
  		goto out_iput;
  
  	mutex_unlock(&c->umount_mutex);

  	return 0;
  
  out_iput:
  	iput(root);
  out_umount:
  	ubifs_umount(c);
  out_unlock:
  	mutex_unlock(&c->umount_mutex);
  out_bdi:
  	bdi_destroy(&c->bdi);
  out_close:
  	ubi_close_volume(c->ubi);

  out:

  	return err;
  }
  
  static int sb_test(struct super_block *sb, void *data)
  {

  	struct ubifs_info *c1 = data;

  	struct ubifs_info *c = sb->s_fs_info;

  	return c->vi.cdev == c1->vi.cdev;
  }
  
  static int sb_set(struct super_block *sb, void *data)
  {
  	sb->s_fs_info = data;
  	return set_anon_super(sb, NULL);

  }

  static struct dentry *ubifs_mount(struct file_system_type *fs_type, int flags,
  			const char *name, void *data)

  {
  	struct ubi_volume_desc *ubi;

  	struct ubifs_info *c;

  	struct super_block *sb;
  	int err;
  
  	dbg_gen("name %s, flags %#x", name, flags);
  
  	/*
  	 * Get UBI device number and volume ID. Mount it read-only so far
  	 * because this might be a new mount point, and UBI allows only one
  	 * read-write user at a time.
  	 */
  	ubi = open_ubi(name, UBI_READONLY);
  	if (IS_ERR(ubi)) {

  		dbg_err("cannot open \"%s\", error %d",
  			name, (int)PTR_ERR(ubi));

  		return ERR_CAST(ubi);

  	}

  	c = alloc_ubifs_info(ubi);
  	if (!c) {
  		err = -ENOMEM;
  		goto out_close;
  	}
  
  	dbg_gen("opened ubi%d_%d", c->vi.ubi_num, c->vi.vol_id);

  	sb = sget(fs_type, sb_test, sb_set, c);

  	if (IS_ERR(sb)) {
  		err = PTR_ERR(sb);

  		kfree(c);

  		goto out_close;

  	}
  
  	if (sb->s_root) {

  		struct ubifs_info *c1 = sb->s_fs_info;

  		kfree(c);

  		/* A new mount point for already mounted UBIFS */
  		dbg_gen("this ubi volume is already mounted");

  		if (!!(flags & MS_RDONLY) != c1->ro_mount) {

  			err = -EBUSY;
  			goto out_deact;
  		}
  	} else {
  		sb->s_flags = flags;

  		err = ubifs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
  		if (err)
  			goto out_deact;
  		/* We do not support atime */
  		sb->s_flags |= MS_ACTIVE | MS_NOATIME;
  	}
  
  	/* 'fill_super()' opens ubi again so we must close it here */
  	ubi_close_volume(ubi);

  	return dget(sb->s_root);

  
  out_deact:

  	deactivate_locked_super(sb);

  out_close:
  	ubi_close_volume(ubi);

  	return ERR_PTR(err);

  }

  static void kill_ubifs_super(struct super_block *s)
  {
  	struct ubifs_info *c = s->s_fs_info;
  	kill_anon_super(s);
  	kfree(c);
  }

  static struct file_system_type ubifs_fs_type = {
  	.name    = "ubifs",
  	.owner   = THIS_MODULE,

  	.mount   = ubifs_mount,

  	.kill_sb = kill_ubifs_super,

  };
  
  /*
   * Inode slab cache constructor.
   */

  static void inode_slab_ctor(void *obj)

  {
  	struct ubifs_inode *ui = obj;
  	inode_init_once(&ui->vfs_inode);
  }
  
  static int __init ubifs_init(void)
  {
  	int err;
  
  	BUILD_BUG_ON(sizeof(struct ubifs_ch) != 24);
  
  	/* Make sure node sizes are 8-byte aligned */
  	BUILD_BUG_ON(UBIFS_CH_SZ        & 7);
  	BUILD_BUG_ON(UBIFS_INO_NODE_SZ  & 7);
  	BUILD_BUG_ON(UBIFS_DENT_NODE_SZ & 7);
  	BUILD_BUG_ON(UBIFS_XENT_NODE_SZ & 7);
  	BUILD_BUG_ON(UBIFS_DATA_NODE_SZ & 7);
  	BUILD_BUG_ON(UBIFS_TRUN_NODE_SZ & 7);
  	BUILD_BUG_ON(UBIFS_SB_NODE_SZ   & 7);
  	BUILD_BUG_ON(UBIFS_MST_NODE_SZ  & 7);
  	BUILD_BUG_ON(UBIFS_REF_NODE_SZ  & 7);
  	BUILD_BUG_ON(UBIFS_CS_NODE_SZ   & 7);
  	BUILD_BUG_ON(UBIFS_ORPH_NODE_SZ & 7);
  
  	BUILD_BUG_ON(UBIFS_MAX_DENT_NODE_SZ & 7);
  	BUILD_BUG_ON(UBIFS_MAX_XENT_NODE_SZ & 7);
  	BUILD_BUG_ON(UBIFS_MAX_DATA_NODE_SZ & 7);
  	BUILD_BUG_ON(UBIFS_MAX_INO_NODE_SZ  & 7);
  	BUILD_BUG_ON(UBIFS_MAX_NODE_SZ      & 7);
  	BUILD_BUG_ON(MIN_WRITE_SZ           & 7);
  
  	/* Check min. node size */
  	BUILD_BUG_ON(UBIFS_INO_NODE_SZ  < MIN_WRITE_SZ);
  	BUILD_BUG_ON(UBIFS_DENT_NODE_SZ < MIN_WRITE_SZ);
  	BUILD_BUG_ON(UBIFS_XENT_NODE_SZ < MIN_WRITE_SZ);
  	BUILD_BUG_ON(UBIFS_TRUN_NODE_SZ < MIN_WRITE_SZ);
  
  	BUILD_BUG_ON(UBIFS_MAX_DENT_NODE_SZ > UBIFS_MAX_NODE_SZ);
  	BUILD_BUG_ON(UBIFS_MAX_XENT_NODE_SZ > UBIFS_MAX_NODE_SZ);
  	BUILD_BUG_ON(UBIFS_MAX_DATA_NODE_SZ > UBIFS_MAX_NODE_SZ);
  	BUILD_BUG_ON(UBIFS_MAX_INO_NODE_SZ  > UBIFS_MAX_NODE_SZ);
  
  	/* Defined node sizes */
  	BUILD_BUG_ON(UBIFS_SB_NODE_SZ  != 4096);
  	BUILD_BUG_ON(UBIFS_MST_NODE_SZ != 512);
  	BUILD_BUG_ON(UBIFS_INO_NODE_SZ != 160);
  	BUILD_BUG_ON(UBIFS_REF_NODE_SZ != 64);
  
  	/*

  	 * We use 2 bit wide bit-fields to store compression type, which should
  	 * be amended if more compressors are added. The bit-fields are:

  	 * @compr_type in 'struct ubifs_inode', @default_compr in
  	 * 'struct ubifs_info' and @compr_type in 'struct ubifs_mount_opts'.

  	 */
  	BUILD_BUG_ON(UBIFS_COMPR_TYPES_CNT > 4);
  
  	/*

  	 * We require that PAGE_CACHE_SIZE is greater-than-or-equal-to
  	 * UBIFS_BLOCK_SIZE. It is assumed that both are powers of 2.
  	 */
  	if (PAGE_CACHE_SIZE < UBIFS_BLOCK_SIZE) {
  		ubifs_err("VFS page cache size is %u bytes, but UBIFS requires"
  			  " at least 4096 bytes",
  			  (unsigned int)PAGE_CACHE_SIZE);
  		return -EINVAL;
  	}

  	ubifs_inode_slab = kmem_cache_create("ubifs_inode_slab",
  				sizeof(struct ubifs_inode), 0,
  				SLAB_MEM_SPREAD | SLAB_RECLAIM_ACCOUNT,
  				&inode_slab_ctor);
  	if (!ubifs_inode_slab)

  		return -ENOMEM;

  
  	register_shrinker(&ubifs_shrinker_info);
  
  	err = ubifs_compressors_init();
  	if (err)

  		goto out_shrinker;
  
  	err = dbg_debugfs_init();
  	if (err)

  		goto out_compr;

  	err = register_filesystem(&ubifs_fs_type);
  	if (err) {
  		ubifs_err("cannot register file system, error %d", err);
  		goto out_dbg;
  	}

  	return 0;

  out_dbg:
  	dbg_debugfs_exit();

  out_compr:

  	ubifs_compressors_exit();
  out_shrinker:

  	unregister_shrinker(&ubifs_shrinker_info);
  	kmem_cache_destroy(ubifs_inode_slab);

  	return err;
  }
  /* late_initcall to let compressors initialize first */
  late_initcall(ubifs_init);
  
  static void __exit ubifs_exit(void)
  {
  	ubifs_assert(list_empty(&ubifs_infos));
  	ubifs_assert(atomic_long_read(&ubifs_clean_zn_cnt) == 0);

  	dbg_debugfs_exit();

  	ubifs_compressors_exit();
  	unregister_shrinker(&ubifs_shrinker_info);
  	kmem_cache_destroy(ubifs_inode_slab);
  	unregister_filesystem(&ubifs_fs_type);
  }
  module_exit(ubifs_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_VERSION(__stringify(UBIFS_VERSION));
  MODULE_AUTHOR("Artem Bityutskiy, Adrian Hunter");
  MODULE_DESCRIPTION("UBIFS - UBI File System");