UBIFS: Implement read-only UBIFS support in U-Boot

The U-Boot UBIFS implementation is largely a direct copy from the current
Linux version (2.6.29-rc6). As already done in the UBI version we have an
"abstraction layer" to redefine or remove some OS calls (e.g. mutex_lock()
...). This makes it possible to use the original Linux code with very
little changes. And by this we can better update to later Linux versions.

I removed some of the Linux features that are not used in the U-Boot
version (e.g. garbage-collection, write support).

Signed-off-by: Stefan Roese <sr@denx.de>
CC: Artem Bityutskiy <dedekind@infradead.org>
CC: Adrian Hunter <ext-Adrian.Hunter@nokia.com>

1 files changed, 1189 insertions, 0 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
new file mode 100644
index 0000000..95f2a41
--- /dev/null
+++ b/fs/ubifs/super.c
@@ -0,0 +1,1189 @@
+/*
+ * 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 "ubifs.h"
+#include <linux/math64.h>
+
+#define INODE_LOCKED_MAX	64
+
+struct super_block *ubifs_sb;
+static struct inode *inodes_locked_down[INODE_LOCKED_MAX];
+
+/* shrinker.c */
+
+/* List of all UBIFS file-system instances */
+struct list_head ubifs_infos;
+
+/* linux/fs/super.c */
+
+static int sb_set(struct super_block *sb, void *data)
+{
+	dev_t *dev = data;
+
+	sb->s_dev = *dev;
+	return 0;
+}
+
+/**
+ *	sget	-	find or create a superblock
+ *	@type:	filesystem type superblock should belong to
+ *	@test:	comparison callback
+ *	@set:	setup callback
+ *	@data:	argument to each of them
+ */
+struct super_block *sget(struct file_system_type *type,
+			int (*test)(struct super_block *,void *),
+			int (*set)(struct super_block *,void *),
+			void *data)
+{
+	struct super_block *s = NULL;
+	int err;
+
+	s = kzalloc(sizeof(struct super_block),  GFP_USER);
+	if (!s) {
+		err = -ENOMEM;
+		return ERR_PTR(err);
+	}
+
+	INIT_LIST_HEAD(&s->s_instances);
+	INIT_LIST_HEAD(&s->s_inodes);
+	s->s_time_gran = 1000000000;
+
+	err = set(s, data);
+	if (err) {
+		return ERR_PTR(err);
+	}
+	s->s_type = type;
+	strncpy(s->s_id, type->name, sizeof(s->s_id));
+	list_add(&s->s_instances, &type->fs_supers);
+	return s;
+}
+
+/**
+ * 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->data_len < 0 || ui->data_len > UBIFS_MAX_INO_DATA)
+		return 4;
+
+	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 *iget_locked(struct super_block *sb, unsigned long ino)
+{
+	struct inode *inode;
+
+	inode = (struct inode *)malloc(sizeof(struct ubifs_inode));
+	if (inode) {
+		inode->i_ino = ino;
+		inode->i_sb = sb;
+		list_add(&inode->i_sb_list, &sb->s_inodes);
+		inode->i_state = I_LOCK | I_NEW;
+	}
+
+	return inode;
+}
+
+int ubifs_iput(struct inode *inode)
+{
+	list_del_init(&inode->i_sb_list);
+
+	free(inode);
+	return 0;
+}
+
+/*
+ * Lock (save) inode in inode array for readback after recovery
+ */
+void iput(struct inode *inode)
+{
+	int i;
+	struct inode *ino;
+
+	/*
+	 * Search end of list
+	 */
+	for (i = 0; i < INODE_LOCKED_MAX; i++) {
+		if (inodes_locked_down[i] == NULL)
+			break;
+	}
+
+	if (i >= INODE_LOCKED_MAX) {
+		ubifs_err("Error, can't lock (save) more inodes while recovery!!!");
+		return;
+	}
+
+	/*
+	 * Allocate and use new inode
+	 */
+	ino = (struct inode *)malloc(sizeof(struct ubifs_inode));
+	memcpy(ino, inode, sizeof(struct ubifs_inode));
+
+	/*
+	 * Finally save inode in array
+	 */
+	inodes_locked_down[i] = ino;
+}
+
+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;
+	int i;
+
+	dbg_gen("inode %lu", inum);
+
+	/*
+	 * U-Boot special handling of locked down inodes via recovery
+	 * e.g. ubifs_recover_size()
+	 */
+	for (i = 0; i < INODE_LOCKED_MAX; i++) {
+		/*
+		 * Exit on last entry (NULL), inode not found in list
+		 */
+		if (inodes_locked_down[i] == NULL)
+			break;
+
+		if (inodes_locked_down[i]->i_ino == inum) {
+			/*
+			 * We found the locked down inode in our array,
+			 * so just return this pointer instead of creating
+			 * a new one.
+			 */
+			return inodes_locked_down[i];
+		}
+	}
+
+	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->synced_i_size = ui->ui_size = inode->i_size;
+
+	err = validate_inode(c, inode);
+	if (err)
+		goto out_invalid;
+
+	if ((inode->i_mode & S_IFMT) == S_IFLNK) {
+		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';
+	}
+
+	kfree(ino);
+	inode->i_state &= ~(I_LOCK | I_NEW);
+	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);
+	return ERR_PTR(err);
+}
+
+/**
+ * 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. 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;
+
+	return 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->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 = (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;
+
+	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->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, 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;
+}
+
+/**
+ * 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;
+}
+
+/**
+ * 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;
+}
+
+/**
+ * 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;
+
+	err = ubifs_debugging_init(c);
+	if (err)
+		return err;
+
+	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;
+
+	/*
+	 * We have to check all CRCs, even for data nodes, when we mount the FS
+	 * (specifically, when we are replaying).
+	 */
+	c->always_chk_crc = 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));
+		goto out_free;
+	}
+
+	dbg_failure_mode_registration(c);
+
+	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;
+	}
+
+	sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num, c->vi.vol_id);
+
+	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;
+	}
+
+	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 (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;
+
+	c->always_chk_crc = 0;
+
+	ubifs_msg("mounted UBI device %d, volume %d, name \"%s\"",
+		  c->vi.ubi_num, c->vi.vol_id, c->vi.name);
+	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("media format:       %d (latest is %d)",
+		  c->fmt_version, UBIFS_FORMAT_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("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:                %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("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("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",
+	        UBIFS_MAX_DATA_NODE_SZ, UBIFS_MAX_INO_NODE_SZ,
+		UBIFS_MAX_DENT_NODE_SZ);
+	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:
+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);
+	kfree(c->cbuf);
+out_free:
+	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);
+
+	spin_lock(&ubifs_infos_lock);
+	list_del(&c->infos_list);
+	spin_unlock(&ubifs_infos_lock);
+
+	if (c->bgt)
+		kthread_stop(c->bgt);
+
+	free_orphans(c);
+	ubifs_lpt_free(c, 0);
+
+	kfree(c->cbuf);
+	kfree(c->rcvrd_mst_node);
+	kfree(c->mst_node);
+	vfree(c->ileb_buf);
+	vfree(c->sbuf);
+	kfree(c->bottom_up_buf);
+	ubifs_debugging_exit(c);
+
+	/* Finally free U-Boot's global copy of superblock */
+	free(ubifs_sb->s_fs_info);
+	free(ubifs_sb);
+}
+
+/**
+ * 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;
+	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_READONLY);
+	if (IS_ERR(c->ubi)) {
+		err = PTR_ERR(c->ubi);
+		goto out_free;
+	}
+
+	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;
+
+	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 = NULL;
+
+	mutex_unlock(&c->umount_mutex);
+	return 0;
+
+out_umount:
+	ubifs_umount(c);
+out_unlock:
+	mutex_unlock(&c->umount_mutex);
+	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 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);
+
+	ubifs_sb = sb;
+	return 0;
+
+out_deact:
+	up_write(&sb->s_umount);
+out_close:
+	ubi_close_volume(ubi);
+	return err;
+}
+
+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;
+	}
+
+	err = -ENOMEM;
+
+	err = ubifs_compressors_init();
+	if (err)
+		goto out_shrinker;
+
+	return 0;
+
+out_shrinker:
+	return err;
+}
+
+/*
+ * ubifsmount...
+ */
+
+static struct file_system_type ubifs_fs_type = {
+	.name    = "ubifs",
+	.owner   = THIS_MODULE,
+	.get_sb  = ubifs_get_sb,
+};
+
+int ubifs_mount(char *vol_name)
+{
+	int flags;
+	char name[80] = "ubi:";
+	void *data;
+	struct vfsmount *mnt;
+	int ret;
+	struct ubifs_info *c;
+
+	/*
+	 * First unmount if allready mounted
+	 */
+	if (ubifs_sb)
+		ubifs_umount(ubifs_sb->s_fs_info);
+
+	INIT_LIST_HEAD(&ubifs_infos);
+
+	/*
+	 * Mount in read-only mode
+	 */
+	flags = MS_RDONLY;
+	strcat(name, vol_name);
+	data = NULL;
+	mnt = NULL;
+	ret = ubifs_get_sb(&ubifs_fs_type, flags, name, data, mnt);
+	if (ret) {
+		printf("Error reading superblock on volume '%s'!\n", name);
+		return -1;
+	}
+
+	c = ubifs_sb->s_fs_info;
+	ubi_close_volume(c->ubi);
+
+	return 0;
+}