UBIFS: add new flash file system

This is a new flash file system. See
http://www.linux-mtd.infradead.org/doc/ubifs.html

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>

1 files changed, 1951 insertions, 0 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
new file mode 100644
index 00000000000..00eb9c68ad0
--- /dev/null
+++ b/fs/ubifs/super.c
@@ -0,0 +1,1951 @@
+/*
+ * 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/random.h>
+#include <linux/kthread.h>
+#include <linux/parser.h>
+#include <linux/seq_file.h>
+#include <linux/mount.h>
+#include "ubifs.h"
+
+/* 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 && (inode->i_mode & S_IFMT) != S_IFREG)
+		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_size(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);
+	inode->i_nlink = 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 readahead */
+	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_destroy_inode(struct inode *inode)
+{
+	struct ubifs_inode *ui = ubifs_inode(inode);
+
+	kfree(ui->data);
+	kmem_cache_free(ubifs_inode_slab, inode);
+}
+
+/*
+ * Note, Linux write-back code calls this without 'i_mutex'.
+ */
+static int ubifs_write_inode(struct inode *inode, int wait)
+{
+	int err;
+	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;
+	}
+
+	dbg_gen("inode %lu", inode->i_ino);
+	err = ubifs_jnl_write_inode(c, inode, 0);
+	if (err)
+		ubifs_err("can't write inode %lu, error %d", inode->i_ino, err);
+
+	ui->dirty = 0;
+	mutex_unlock(&ui->ui_mutex);
+	ubifs_release_dirty_inode_budget(c, ui);
+	return err;
+}
+
+static void ubifs_delete_inode(struct inode *inode)
+{
+	int err;
+	struct ubifs_info *c = inode->i_sb->s_fs_info;
+
+	if (ubifs_inode(inode)->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", inode->i_ino);
+	ubifs_assert(!atomic_read(&inode->i_count));
+	ubifs_assert(inode->i_nlink == 0);
+
+	truncate_inode_pages(&inode->i_data, 0);
+	if (is_bad_inode(inode))
+		goto out;
+
+	ubifs_inode(inode)->ui_size = inode->i_size = 0;
+	err = ubifs_jnl_write_inode(c, inode, 1);
+	if (err)
+		/*
+		 * Worst case we have a lost orphan inode wasting space, so a
+		 * simple error message is ok here.
+		 */
+		ubifs_err("can't write inode %lu, error %d", inode->i_ino, err);
+out:
+	clear_inode(inode);
+}
+
+static void ubifs_dirty_inode(struct inode *inode)
+{
+	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;
+
+	free = ubifs_budg_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;
+
+	return 0;
+}
+
+static int ubifs_show_options(struct seq_file *s, struct vfsmount *mnt)
+{
+	struct ubifs_info *c = mnt->mnt_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");
+
+	return 0;
+}
+
+static int ubifs_sync_fs(struct super_block *sb, int wait)
+{
+	struct ubifs_info *c = sb->s_fs_info;
+	int i, ret = 0, err;
+
+	if (c->jheads)
+		for (i = 0; i < c->jhead_cnt; i++) {
+			err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
+			if (err && !ret)
+				ret = err;
+		}
+	/*
+	 * We ought to call sync for c->ubi but it does not have one. If it had
+	 * it would in turn call mtd->sync, however mtd operations are
+	 * synchronous anyway, so we don't lose any sleep here.
+	 */
+	return ret;
+}
+
+/**
+ * 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->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;
+
+	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;
+	}
+
+	/*
+	 * 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;
+	}
+
+	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.
+	 *
+	 * Dead space is the space which cannot be used. Its watermark is
+	 * equivalent to min. I/O unit or minimum node size if it is greater
+	 * then min. I/O unit.
+	 *
+	 * Dark space is the space which might be used, or might not, depending
+	 * on which node should be written to the LEB. Its watermark is
+	 * equivalent to maximum UBIFS node size.
+	 */
+	c->dead_wm = ALIGN(MIN_WRITE_SZ, c->min_io_size);
+	c->dark_wm = ALIGN(UBIFS_MAX_NODE_SZ, c->min_io_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_late - 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_late(struct ubifs_info *c)
+{
+	int tmp, err;
+	uint64_t 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;
+	tmp = do_div(tmp64, c->leb_size);
+	c->max_bud_cnt = tmp64 + !!tmp;
+	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->inode_budget'.
+	 */
+	c->page_budget = UBIFS_MAX_DATA_NODE_SZ * UBIFS_BLOCKS_PER_PAGE;
+	c->inode_budget = UBIFS_INO_NODE_SZ;
+	c->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 = (uint64_t)(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;
+
+	c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);
+
+	/*
+	 * 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 and the LEB which is reserved for
+	 * deletions.
+	 *
+	 * Review 'ubifs_calc_available()' if changing this calculation.
+	 */
+	tmp64 = c->main_lebs - 2;
+	tmp64 *= (uint64_t)c->leb_size - c->dark_wm;
+	tmp64 = ubifs_reported_space(c, tmp64);
+	c->block_cnt = tmp64 >> UBIFS_BLOCK_SHIFT;
+
+	return 0;
+}
+
+/**
+ * take_gc_lnum - reserve GC LEB.
+ * @c: UBIFS file-system description object
+ *
+ * This function ensures that the LEB reserved for garbage collection is
+ * unmapped and 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;
+	}
+
+	err = ubifs_leb_unmap(c, c->gc_lnum);
+	if (err)
+		return err;
+
+	/* 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[BASEHD].wbuf.dtype = UBI_SHORTTERM;
+	/*
+	 * Garbage Collector head likely contains long-term data and
+	 * does not need to be synchronized by timer.
+	 */
+	c->jheads[GCHD].wbuf.dtype = UBI_LONGTERM;
+	c->jheads[GCHD].wbuf.timeout = 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 = ubi_is_mapped(c->ubi, 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_err: just end of array marker
+ */
+enum {
+	Opt_fast_unmount,
+	Opt_norm_unmount,
+	Opt_err,
+};
+
+static match_table_t tokens = {
+	{Opt_fast_unmount, "fast_unmount"},
+	{Opt_norm_unmount, "norm_unmount"},
+	{Opt_err, NULL},
+};
+
+/**
+ * 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) {
+		case Opt_fast_unmount:
+			c->mount_opts.unmount_mode = 2;
+			c->fast_unmount = 1;
+			break;
+		case Opt_norm_unmount:
+			c->mount_opts.unmount_mode = 1;
+			c->fast_unmount = 0;
+			break;
+		default:
+			ubifs_err("unrecognized mount option \"%s\" "
+				  "or missing value", p);
+			return -EINVAL;
+		}
+	}
+
+	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);
+}
+
+/**
+ * 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)
+{
+	struct super_block *sb = c->vfs_sb;
+	int err, mounted_read_only = (sb->s_flags & MS_RDONLY);
+	long long x;
+	size_t sz;
+
+	err = init_constants_early(c);
+	if (err)
+		return err;
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+	c->dbg_buf = vmalloc(c->leb_size);
+	if (!c->dbg_buf)
+		return -ENOMEM;
+#endif
+
+	err = check_volume_empty(c);
+	if (err)
+		goto out_free;
+
+	if (c->empty && (mounted_read_only || 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 && !mounted_read_only) {
+		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 (!mounted_read_only) {
+		c->ileb_buf = vmalloc(c->leb_size);
+		if (!c->ileb_buf)
+			goto out_free;
+	}
+
+	err = ubifs_read_superblock(c);
+	if (err)
+		goto out_free;
+
+	/*
+	 * Make sure the compressor which is set as the default on in the
+	 * superblock was actually compiled in.
+	 */
+	if (!ubifs_compr_present(c->default_compr)) {
+		ubifs_warn("'%s' compressor is set by superblock, but not "
+			   "compiled in", ubifs_compr_name(c->default_compr));
+		c->default_compr = UBIFS_COMPR_NONE;
+	}
+
+	dbg_failure_mode_registration(c);
+
+	err = init_constants_late(c);
+	if (err)
+		goto out_dereg;
+
+	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_dereg;
+	}
+
+	if (!mounted_read_only) {
+		err = alloc_wbufs(c);
+		if (err)
+			goto out_cbuf;
+
+		/* Create background thread */
+		sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num,
+			c->vi.vol_id);
+		c->bgt = kthread_create(ubifs_bg_thread, c, c->bgt_name);
+		if (!c->bgt)
+			c->bgt = ERR_PTR(-EINVAL);
+		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;
+
+	if ((c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY)) != 0) {
+		ubifs_msg("recovery needed");
+		c->need_recovery = 1;
+		if (!mounted_read_only) {
+			err = ubifs_recover_inl_heads(c, c->sbuf);
+			if (err)
+				goto out_master;
+		}
+	} else if (!mounted_read_only) {
+		/*
+		 * 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_master;
+	}
+
+	err = ubifs_lpt_init(c, 1, !mounted_read_only);
+	if (err)
+		goto out_lpt;
+
+	err = dbg_check_idx_size(c, c->old_idx_sz);
+	if (err)
+		goto out_lpt;
+
+	err = ubifs_replay_journal(c);
+	if (err)
+		goto out_journal;
+
+	err = ubifs_mount_orphans(c, c->need_recovery, mounted_read_only);
+	if (err)
+		goto out_orphans;
+
+	if (!mounted_read_only) {
+		int lnum;
+
+		/* Check for enough free space */
+		if (ubifs_calc_available(c, c->min_idx_lebs) <= 0) {
+			ubifs_err("insufficient available space");
+			err = -EINVAL;
+			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);
+		} else
+			err = take_gc_lnum(c);
+		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;
+	}
+
+	spin_lock(&ubifs_infos_lock);
+	list_add_tail(&c->infos_list, &ubifs_infos);
+	spin_unlock(&ubifs_infos_lock);
+
+	if (c->need_recovery) {
+		if (mounted_read_only)
+			ubifs_msg("recovery deferred");
+		else {
+			c->need_recovery = 0;
+			ubifs_msg("recovery completed");
+		}
+	}
+
+	err = dbg_check_filesystem(c);
+	if (err)
+		goto out_infos;
+
+	ubifs_msg("mounted UBI device %d, volume %d", c->vi.ubi_num,
+		  c->vi.vol_id);
+	if (mounted_read_only)
+		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("default compressor: %s", ubifs_compr_name(c->default_compr));
+	ubifs_msg("media format %d, latest format %d",
+		  c->fmt_version, UBIFS_FORMAT_VERSION);
+
+	dbg_msg("compiled on:         " __DATE__ " at " __TIME__);
+	dbg_msg("min. I/O unit size:  %d bytes", c->min_io_size);
+	dbg_msg("LEB size:            %d bytes (%d KiB)",
+		c->leb_size, c->leb_size / 1024);
+	dbg_msg("data journal heads:  %d",
+		c->jhead_cnt - NONDATA_JHEADS_CNT);
+	dbg_msg("UUID:                %02X%02X%02X%02X-%02X%02X"
+	       "-%02X%02X-%02X%02X-%02X%02X%02X%02X%02X%02X",
+	       c->uuid[0], c->uuid[1], c->uuid[2], c->uuid[3],
+	       c->uuid[4], c->uuid[5], c->uuid[6], c->uuid[7],
+	       c->uuid[8], c->uuid[9], c->uuid[10], c->uuid[11],
+	       c->uuid[12], c->uuid[13], c->uuid[14], c->uuid[15]);
+	dbg_msg("fast unmount:        %d", c->fast_unmount);
+	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->old_idx_sz, c->old_idx_sz >> 10, c->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("dead watermark:      %d", c->dead_wm);
+	dbg_msg("dark watermark:      %d", c->dark_wm);
+	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_dereg:
+	dbg_failure_mode_deregistration(c);
+out_free:
+	vfree(c->ileb_buf);
+	vfree(c->sbuf);
+	kfree(c->bottom_up_buf);
+	UBIFS_DBG(vfree(c->dbg_buf));
+	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);
+
+	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);
+	vfree(c->sbuf);
+	kfree(c->bottom_up_buf);
+	UBIFS_DBG(vfree(c->dbg_buf));
+	vfree(c->ileb_buf);
+	dbg_failure_mode_deregistration(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->ro_media)
+		return -EINVAL;
+
+	mutex_lock(&c->umount_mutex);
+	c->remounting_rw = 1;
+
+	/* Check for enough free space */
+	if (ubifs_calc_available(c, c->min_idx_lebs) <= 0) {
+		ubifs_err("insufficient available space");
+		err = -EINVAL;
+		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);
+		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;
+	}
+
+	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;
+	}
+
+	err = ubifs_lpt_init(c, 0, 1);
+	if (err)
+		goto out;
+
+	err = alloc_wbufs(c);
+	if (err)
+		goto out;
+
+	ubifs_create_buds_lists(c);
+
+	/* Create background thread */
+	c->bgt = kthread_create(ubifs_bg_thread, c, c->bgt_name);
+	if (!c->bgt)
+		c->bgt = ERR_PTR(-EINVAL);
+	if (IS_ERR(c->bgt)) {
+		err = PTR_ERR(c->bgt);
+		c->bgt = NULL;
+		ubifs_err("cannot spawn \"%s\", error %d",
+			  c->bgt_name, err);
+		return err;
+	}
+	wake_up_process(c->bgt);
+
+	c->orph_buf = vmalloc(c->leb_size);
+	if (!c->orph_buf)
+		return -ENOMEM;
+
+	/* 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 = take_gc_lnum(c);
+	if (err)
+		goto out;
+
+	if (c->need_recovery) {
+		c->need_recovery = 0;
+		ubifs_msg("deferred recovery completed");
+	}
+
+	dbg_gen("re-mounted read-write");
+	c->vfs_sb->s_flags &= ~MS_RDONLY;
+	c->remounting_rw = 0;
+	mutex_unlock(&c->umount_mutex);
+	return 0;
+
+out:
+	vfree(c->orph_buf);
+	c->orph_buf = NULL;
+	if (c->bgt) {
+		kthread_stop(c->bgt);
+		c->bgt = NULL;
+	}
+	free_wbufs(c);
+	vfree(c->ileb_buf);
+	c->ileb_buf = NULL;
+	ubifs_lpt_free(c, 1);
+	c->remounting_rw = 0;
+	mutex_unlock(&c->umount_mutex);
+	return err;
+}
+
+/**
+ * commit_on_unmount - commit the journal when un-mounting.
+ * @c: UBIFS file-system description object
+ *
+ * This function is called during un-mounting and it commits the journal unless
+ * the "fast unmount" mode is enabled. It also avoids committing the journal if
+ * it contains too few data.
+ *
+ * Sometimes recovery requires the journal to be committed at least once, and
+ * this function takes care about this.
+ */
+static void commit_on_unmount(struct ubifs_info *c)
+{
+	if (!c->fast_unmount) {
+		long long bud_bytes;
+
+		spin_lock(&c->buds_lock);
+		bud_bytes = c->bud_bytes;
+		spin_unlock(&c->buds_lock);
+		if (bud_bytes > c->leb_size)
+			ubifs_run_commit(c);
+	}
+}
+
+/**
+ * ubifs_remount_ro - re-mount in read-only mode.
+ * @c: UBIFS file-system description object
+ *
+ * We rely on VFS to have 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);
+	commit_on_unmount(c);
+
+	mutex_lock(&c->umount_mutex);
+	if (c->bgt) {
+		kthread_stop(c->bgt);
+		c->bgt = NULL;
+	}
+
+	for (i = 0; i < c->jhead_cnt; i++) {
+		ubifs_wbuf_sync(&c->jheads[i].wbuf);
+		del_timer_sync(&c->jheads[i].wbuf.timer);
+	}
+
+	if (!c->ro_media) {
+		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);
+	}
+
+	ubifs_destroy_idx_gc(c);
+	free_wbufs(c);
+	vfree(c->orph_buf);
+	c->orph_buf = NULL;
+	vfree(c->ileb_buf);
+	c->ileb_buf = NULL;
+	ubifs_lpt_free(c, 1);
+	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.
+	 */
+	ubifs_assert(atomic_long_read(&c->dirty_pg_cnt) == 0);
+	ubifs_assert(c->budg_idx_growth == 0);
+	ubifs_assert(c->budg_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->vfs_sb->s_flags & MS_RDONLY)) {
+		/*
+		 * 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;
+		}
+
+		/* Synchronize write-buffers */
+		if (c->jheads)
+			for (i = 0; i < c->jhead_cnt; i++) {
+				ubifs_wbuf_sync(&c->jheads[i].wbuf);
+				del_timer_sync(&c->jheads[i].wbuf.timer);
+			}
+
+		/*
+		 * On fatal errors c->ro_media is set to 1, in which case we do
+		 * not write the master node.
+		 */
+		if (!c->ro_media) {
+			/*
+			 * We are being cleanly unmounted which means the
+			 * orphans were killed - indicate this in the master
+			 * node. Also save the reserved GC LEB number.
+			 */
+			int err;
+
+			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);
+		}
+	}
+
+	ubifs_umount(c);
+	bdi_destroy(&c->bdi);
+	ubi_close_volume(c->ubi);
+	mutex_unlock(&c->umount_mutex);
+	kfree(c);
+}
+
+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 ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
+		err = ubifs_remount_rw(c);
+		if (err)
+			return err;
+	} else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY))
+		ubifs_remount_ro(c);
+
+	return 0;
+}
+
+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,
+	.delete_inode  = ubifs_delete_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
+ *
+ * There are several ways to specify UBI volumes when mounting UBIFS:
+ * o ubiX_Y    - UBI device number X, volume Y;
+ * o ubiY      - 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 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)
+{
+	int dev, vol;
+	char *endptr;
+
+	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 int ubifs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct ubi_volume_desc *ubi = sb->s_fs_info;
+	struct ubifs_info *c;
+	struct inode *root;
+	int err;
+
+	c = kzalloc(sizeof(struct ubifs_info), GFP_KERNEL);
+	if (!c)
+		return -ENOMEM;
+
+	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);
+	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->highest_inum = UBIFS_FIRST_INO;
+	get_random_bytes(&c->vfs_gen, sizeof(int));
+	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);
+
+	/* 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_free;
+	}
+
+	/*
+	 * UBIFS provids 'backing_dev_info' in order to disable readahead. 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 readahead I/O as well i.e. completely pointless.
+	 *
+	 * Read-ahead will be disabled because @c->bdi.ra_pages is 0.
+	 */
+	c->bdi.capabilities = BDI_CAP_MAP_COPY;
+	c->bdi.unplug_io_fn = default_unplug_io_fn;
+	err  = bdi_init(&c->bdi);
+	if (err)
+		goto out_close;
+
+	err = ubifs_parse_options(c, data, 0);
+	if (err)
+		goto out_bdi;
+
+	c->vfs_sb = sb;
+
+	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_dev = c->vi.cdev;
+	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_free:
+	kfree(c);
+	return err;
+}
+
+static int sb_test(struct super_block *sb, void *data)
+{
+	dev_t *dev = data;
+
+	return sb->s_dev == *dev;
+}
+
+static int sb_set(struct super_block *sb, void *data)
+{
+	dev_t *dev = data;
+
+	sb->s_dev = *dev;
+	return 0;
+}
+
+static int ubifs_get_sb(struct file_system_type *fs_type, int flags,
+			const char *name, void *data, struct vfsmount *mnt)
+{
+	struct ubi_volume_desc *ubi;
+	struct ubi_volume_info vi;
+	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)) {
+		ubifs_err("cannot open \"%s\", error %d",
+			  name, (int)PTR_ERR(ubi));
+		return PTR_ERR(ubi);
+	}
+	ubi_get_volume_info(ubi, &vi);
+
+	dbg_gen("opened ubi%d_%d", vi.ubi_num, vi.vol_id);
+
+	sb = sget(fs_type, &sb_test, &sb_set, &vi.cdev);
+	if (IS_ERR(sb)) {
+		err = PTR_ERR(sb);
+		goto out_close;
+	}
+
+	if (sb->s_root) {
+		/* A new mount point for already mounted UBIFS */
+		dbg_gen("this ubi volume is already mounted");
+		if ((flags ^ sb->s_flags) & MS_RDONLY) {
+			err = -EBUSY;
+			goto out_deact;
+		}
+	} else {
+		sb->s_flags = flags;
+		/*
+		 * Pass 'ubi' to 'fill_super()' in sb->s_fs_info where it is
+		 * replaced by 'c'.
+		 */
+		sb->s_fs_info = ubi;
+		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 simple_set_mnt(mnt, sb);
+
+out_deact:
+	up_write(&sb->s_umount);
+	deactivate_super(sb);
+out_close:
+	ubi_close_volume(ubi);
+	return err;
+}
+
+static void ubifs_kill_sb(struct super_block *sb)
+{
+	struct ubifs_info *c = sb->s_fs_info;
+
+	/*
+	 * We do 'commit_on_unmount()' here instead of 'ubifs_put_super()'
+	 * in order to be outside BKL.
+	 */
+	if (sb->s_root && !(sb->s_flags & MS_RDONLY))
+		commit_on_unmount(c);
+	/* The un-mount routine is actually done in put_super() */
+	generic_shutdown_super(sb);
+}
+
+static struct file_system_type ubifs_fs_type = {
+	.name    = "ubifs",
+	.owner   = THIS_MODULE,
+	.get_sb  = ubifs_get_sb,
+	.kill_sb = ubifs_kill_sb
+};
+
+/*
+ * Inode slab cache constructor.
+ */
+static void inode_slab_ctor(struct kmem_cache *cachep, 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 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;
+	}
+
+	err = register_filesystem(&ubifs_fs_type);
+	if (err) {
+		ubifs_err("cannot register file system, error %d", err);
+		return err;
+	}
+
+	err = -ENOMEM;
+	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)
+		goto out_reg;
+
+	register_shrinker(&ubifs_shrinker_info);
+
+	err = ubifs_compressors_init();
+	if (err)
+		goto out_compr;
+
+	return 0;
+
+out_compr:
+	unregister_shrinker(&ubifs_shrinker_info);
+	kmem_cache_destroy(ubifs_inode_slab);
+out_reg:
+	unregister_filesystem(&ubifs_fs_type);
+	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);
+
+	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");