Merge branch 'for_linus' of git://git.infradead.org/~dedekind/ubifs-2.6

* 'for_linus' of git://git.infradead.org/~dedekind/ubifs-2.6:
  UBIFS: include to compilation
  UBIFS: add new flash file system
  UBIFS: add brief documentation
  MAINTAINERS: add UBIFS section
  do_mounts: allow UBI root device name
  VFS: export sync_sb_inodes
  VFS: move inode_lock into sync_sb_inodes

Documentation/filesystems/ubifs.txt

+Introduction
+=============
+
+UBIFS file-system stands for UBI File System. UBI stands for "Unsorted
+Block Images". UBIFS is a flash file system, which means it is designed
+to work with flash devices. It is important to understand, that UBIFS
+is completely different to any traditional file-system in Linux, like
+Ext2, XFS, JFS, etc. UBIFS represents a separate class of file-systems
+which work with MTD devices, not block devices. The other Linux
+file-system of this class is JFFS2.
+
+To make it more clear, here is a small comparison of MTD devices and
+block devices.
+
+1 MTD devices represent flash devices and they consist of eraseblocks of
+  rather large size, typically about 128KiB. Block devices consist of
+  small blocks, typically 512 bytes.
+2 MTD devices support 3 main operations - read from some offset within an
+  eraseblock, write to some offset within an eraseblock, and erase a whole
+  eraseblock. Block  devices support 2 main operations - read a whole
+  block and write a whole block.
+3 The whole eraseblock has to be erased before it becomes possible to
+  re-write its contents. Blocks may be just re-written.
+4 Eraseblocks become worn out after some number of erase cycles -
+  typically 100K-1G for SLC NAND and NOR flashes, and 1K-10K for MLC
+  NAND flashes. Blocks do not have the wear-out property.
+5 Eraseblocks may become bad (only on NAND flashes) and software should
+  deal with this. Blocks on hard drives typically do not become bad,
+  because hardware has mechanisms to substitute bad blocks, at least in
+  modern LBA disks.
+
+It should be quite obvious why UBIFS is very different to traditional
+file-systems.
+
+UBIFS works on top of UBI. UBI is a separate software layer which may be
+found in drivers/mtd/ubi. UBI is basically a volume management and
+wear-leveling layer. It provides so called UBI volumes which is a higher
+level abstraction than a MTD device. The programming model of UBI devices
+is very similar to MTD devices - they still consist of large eraseblocks,
+they have read/write/erase operations, but UBI devices are devoid of
+limitations like wear and bad blocks (items 4 and 5 in the above list).
+
+In a sense, UBIFS is a next generation of JFFS2 file-system, but it is
+very different and incompatible to JFFS2. The following are the main
+differences.
+
+* JFFS2 works on top of MTD devices, UBIFS depends on UBI and works on
+  top of UBI volumes.
+* JFFS2 does not have on-media index and has to build it while mounting,
+  which requires full media scan. UBIFS maintains the FS indexing
+  information on the flash media and does not require full media scan,
+  so it mounts many times faster than JFFS2.
+* JFFS2 is a write-through file-system, while UBIFS supports write-back,
+  which makes UBIFS much faster on writes.
+
+Similarly to JFFS2, UBIFS supports on-the-flight compression which makes
+it possible to fit quite a lot of data to the flash.
+
+Similarly to JFFS2, UBIFS is tolerant of unclean reboots and power-cuts.
+It does not need stuff like ckfs.ext2. UBIFS automatically replays its
+journal and recovers from crashes, ensuring that the on-flash data
+structures are consistent.
+
+UBIFS scales logarithmically (most of the data structures it uses are
+trees), so the mount time and memory consumption do not linearly depend
+on the flash size, like in case of JFFS2. This is because UBIFS
+maintains the FS index on the flash media. However, UBIFS depends on
+UBI, which scales linearly. So overall UBI/UBIFS stack scales linearly.
+Nevertheless, UBI/UBIFS scales considerably better than JFFS2.
+
+The authors of UBIFS believe, that it is possible to develop UBI2 which
+would scale logarithmically as well. UBI2 would support the same API as UBI,
+but it would be binary incompatible to UBI. So UBIFS would not need to be
+changed to use UBI2
+
+
+Mount options
+=============
+
+(*) == default.
+
+norm_unmount (*)	commit on unmount; the journal is committed
+			when the file-system is unmounted so that the
+			next mount does not have to replay the journal
+			and it becomes very fast;
+fast_unmount		do not commit on unmount; this option makes
+			unmount faster, but the next mount slower
+			because of the need to replay the journal.
+
+
+Quick usage instructions
+========================
+
+The UBI volume to mount is specified using "ubiX_Y" or "ubiX:NAME" syntax,
+where "X" is UBI device number, "Y" is UBI volume number, and "NAME" is
+UBI volume name.
+
+Mount volume 0 on UBI device 0 to /mnt/ubifs:
+$ mount -t ubifs ubi0_0 /mnt/ubifs
+
+Mount "rootfs" volume of UBI device 0 to /mnt/ubifs ("rootfs" is volume
+name):
+$ mount -t ubifs ubi0:rootfs /mnt/ubifs
+
+The following is an example of the kernel boot arguments to attach mtd0
+to UBI and mount volume "rootfs":
+ubi.mtd=0 root=ubi0:rootfs rootfstype=ubifs
+
+
+Module Parameters for Debugging
+===============================
+
+When UBIFS has been compiled with debugging enabled, there are 3 module
+parameters that are available to control aspects of testing and debugging.
+The parameters are unsigned integers where each bit controls an option.
+The parameters are:
+
+debug_msgs	Selects which debug messages to display, as follows:
+
+		Message Type				Flag value
+
+		General messages			1
+		Journal messages			2
+		Mount messages				4
+		Commit messages				8
+		LEB search messages			16
+		Budgeting messages			32
+		Garbage collection messages		64
+		Tree Node Cache (TNC) messages		128
+		LEB properties (lprops) messages	256
+		Input/output messages			512
+		Log messages				1024
+		Scan messages				2048
+		Recovery messages			4096
+
+debug_chks	Selects extra checks that UBIFS can do while running:
+
+		Check					Flag value
+
+		General checks				1
+		Check Tree Node Cache (TNC)		2
+		Check indexing tree size		4
+		Check orphan area			8
+		Check old indexing tree			16
+		Check LEB properties (lprops)		32
+		Check leaf nodes and inodes		64
+
+debug_tsts	Selects a mode of testing, as follows:
+
+		Test mode				Flag value
+
+		Force in-the-gaps method		2
+		Failure mode for recovery testing	4
+
+For example, set debug_msgs to 5 to display General messages and Mount
+messages.
+
+
+References
+==========
+
+UBIFS documentation and FAQ/HOWTO at the MTD web site:
+http://www.linux-mtd.infradead.org/doc/ubifs.html
+http://www.linux-mtd.infradead.org/faq/ubifs.html

MAINTAINERS

@@ -2336,6 +2336,16 @@ L:	linux-mtd@lists.infradead.org
 W:	http://www.linux-mtd.infradead.org/doc/jffs2.html
 S:	Maintained
 
+UBI FILE SYSTEM (UBIFS)
+P:	Artem Bityutskiy
+M:	dedekind@infradead.org
+P:	Adrian Hunter
+M:	ext-adrian.hunter@nokia.com
+L:	linux-mtd@lists.infradead.org
+T:	git git://git.infradead.org/~dedekind/ubifs-2.6.git
+W:	http://www.linux-mtd.infradead.org/doc/ubifs.html
+S:	Maintained
+
 JFS FILESYSTEM
 P:	Dave Kleikamp
 M:	shaggy@austin.ibm.com

fs/Kconfig

@@ -1375,6 +1375,9 @@ config JFFS2_CMODE_FAVOURLZO
 
 endchoice
 
+# UBIFS File system configuration
+source "fs/ubifs/Kconfig"
+
 config CRAMFS
 	tristate "Compressed ROM file system support (cramfs)"
 	depends on BLOCK

fs/Makefile

@@ -101,6 +101,7 @@ obj-$(CONFIG_NTFS_FS)		+= ntfs/
 obj-$(CONFIG_UFS_FS)		+= ufs/
 obj-$(CONFIG_EFS_FS)		+= efs/
 obj-$(CONFIG_JFFS2_FS)		+= jffs2/
+obj-$(CONFIG_UBIFS_FS)		+= ubifs/
 obj-$(CONFIG_AFFS_FS)		+= affs/
 obj-$(CONFIG_ROMFS_FS)		+= romfs/
 obj-$(CONFIG_QNX4FS_FS)		+= qnx4/

fs/fs-writeback.c

@@ -424,8 +424,6 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
  * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so
  * that it can be located for waiting on in __writeback_single_inode().
  *
- * Called under inode_lock.
- *
  * If `bdi' is non-zero then we're being asked to writeback a specific queue.
  * This function assumes that the blockdev superblock's inodes are backed by
  * a variety of queues, so all inodes are searched.  For other superblocks,
@@ -441,11 +439,12 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
  * on the writer throttling path, and we get decent balancing between many
  * throttled threads: we don't want them all piling up on inode_sync_wait.
  */
-static void
-sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
+void generic_sync_sb_inodes(struct super_block *sb,
+				struct writeback_control *wbc)
 {
 	const unsigned long start = jiffies;	/* livelock avoidance */
 
+	spin_lock(&inode_lock);
 	if (!wbc->for_kupdate || list_empty(&sb->s_io))
 		queue_io(sb, wbc->older_than_this);
 
@@ -524,8 +523,16 @@ sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
 		if (!list_empty(&sb->s_more_io))
 			wbc->more_io = 1;
 	}
+	spin_unlock(&inode_lock);
 	return;		/* Leave any unwritten inodes on s_io */
 }
+EXPORT_SYMBOL_GPL(generic_sync_sb_inodes);
+
+static void sync_sb_inodes(struct super_block *sb,
+				struct writeback_control *wbc)
+{
+	generic_sync_sb_inodes(sb, wbc);
+}
 
 /*
  * Start writeback of dirty pagecache data against all unlocked inodes.
@@ -565,11 +572,8 @@ writeback_inodes(struct writeback_control *wbc)
 			 * be unmounted by the time it is released.
 			 */
 			if (down_read_trylock(&sb->s_umount)) {
-				if (sb->s_root) {
-					spin_lock(&inode_lock);
+				if (sb->s_root)
 					sync_sb_inodes(sb, wbc);
-					spin_unlock(&inode_lock);
-				}
 				up_read(&sb->s_umount);
 			}
 			spin_lock(&sb_lock);
@@ -607,9 +611,7 @@ void sync_inodes_sb(struct super_block *sb, int wait)
 			(inodes_stat.nr_inodes - inodes_stat.nr_unused) +
 			nr_dirty + nr_unstable;
 	wbc.nr_to_write += wbc.nr_to_write / 2;		/* Bit more for luck */
-	spin_lock(&inode_lock);
 	sync_sb_inodes(sb, &wbc);
-	spin_unlock(&inode_lock);
 }
 
 /*

fs/ubifs/Kconfig

+config UBIFS_FS
+	tristate "UBIFS file system support"
+	select CRC16
+	select CRC32
+	select CRYPTO if UBIFS_FS_ADVANCED_COMPR
+	select CRYPTO if UBIFS_FS_LZO
+	select CRYPTO if UBIFS_FS_ZLIB
+	select CRYPTO_LZO if UBIFS_FS_LZO
+	select CRYPTO_DEFLATE if UBIFS_FS_ZLIB
+	depends on MTD_UBI
+	help
+	  UBIFS is a file system for flash devices which works on top of UBI.
+
+config UBIFS_FS_XATTR
+	bool "Extended attributes support"
+	depends on UBIFS_FS
+	help
+	  This option enables support of extended attributes.
+
+config UBIFS_FS_ADVANCED_COMPR
+	bool "Advanced compression options"
+	depends on UBIFS_FS
+	help
+	  This option allows to explicitly choose which compressions, if any,
+	  are enabled in UBIFS. Removing compressors means inbility to read
+	  existing file systems.
+
+	  If unsure, say 'N'.
+
+config UBIFS_FS_LZO
+	bool "LZO compression support" if UBIFS_FS_ADVANCED_COMPR
+	depends on UBIFS_FS
+	default y
+	help
+	   LZO compressor is generally faster then zlib but compresses worse.
+	   Say 'Y' if unsure.
+
+config UBIFS_FS_ZLIB
+	bool "ZLIB compression support" if UBIFS_FS_ADVANCED_COMPR
+	depends on UBIFS_FS
+	default y
+	help
+	  Zlib copresses better then LZO but it is slower. Say 'Y' if unsure.
+
+# Debugging-related stuff
+config UBIFS_FS_DEBUG
+	bool "Enable debugging"
+	depends on UBIFS_FS
+	select DEBUG_FS
+	select KALLSYMS_ALL
+	help
+	  This option enables UBIFS debugging.
+
+config UBIFS_FS_DEBUG_MSG_LVL
+	int "Default message level (0 = no extra messages, 3 = lots)"
+	depends on UBIFS_FS_DEBUG
+	default "0"
+	help
+	  This controls the amount of debugging messages produced by UBIFS.
+	  If reporting bugs, please try to have available a full dump of the
+	  messages at level 1 while the misbehaviour was occurring. Level 2
+	  may become necessary if level 1 messages were not enough to find the
+	  bug. Generally Level 3 should be avoided.
+
+config UBIFS_FS_DEBUG_CHKS
+	bool "Enable extra checks"
+	depends on UBIFS_FS_DEBUG
+	help
+	  If extra checks are enabled UBIFS will check the consistency of its
+	  internal data structures during operation. However, UBIFS performance
+	  is dramatically slower when this option is selected especially if the
+	  file system is large.

fs/ubifs/Makefile

+obj-$(CONFIG_UBIFS_FS) += ubifs.o
+
+ubifs-y += shrinker.o journal.o file.o dir.o super.o sb.o io.o
+ubifs-y += tnc.o master.o scan.o replay.o log.o commit.o gc.o orphan.o
+ubifs-y += budget.o find.o tnc_commit.o compress.o lpt.o lprops.o
+ubifs-y += recovery.o ioctl.o lpt_commit.o tnc_misc.o
+
+ubifs-$(CONFIG_UBIFS_FS_DEBUG) += debug.o
+ubifs-$(CONFIG_UBIFS_FS_XATTR) += xattr.o

fs/ubifs/compress.c

+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation.
+ * Copyright (C) 2006, 2007 University of Szeged, Hungary
+ *
+ * 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: Adrian Hunter
+ *          Artem Bityutskiy (Битюцкий Артём)
+ *          Zoltan Sogor
+ */
+
+/*
+ * This file provides a single place to access to compression and
+ * decompression.
+ */
+
+#include <linux/crypto.h>
+#include "ubifs.h"
+
+/* Fake description object for the "none" compressor */
+static struct ubifs_compressor none_compr = {
+	.compr_type = UBIFS_COMPR_NONE,
+	.name = "no compression",
+	.capi_name = "",
+};
+
+#ifdef CONFIG_UBIFS_FS_LZO
+static DEFINE_MUTEX(lzo_mutex);
+
+static struct ubifs_compressor lzo_compr = {
+	.compr_type = UBIFS_COMPR_LZO,
+	.comp_mutex = &lzo_mutex,
+	.name = "LZO",
+	.capi_name = "lzo",
+};
+#else
+static struct ubifs_compressor lzo_compr = {
+	.compr_type = UBIFS_COMPR_LZO,
+	.name = "LZO",
+};
+#endif
+
+#ifdef CONFIG_UBIFS_FS_ZLIB
+static DEFINE_MUTEX(deflate_mutex);
+static DEFINE_MUTEX(inflate_mutex);
+
+static struct ubifs_compressor zlib_compr = {
+	.compr_type = UBIFS_COMPR_ZLIB,
+	.comp_mutex = &deflate_mutex,
+	.decomp_mutex = &inflate_mutex,
+	.name = "zlib",
+	.capi_name = "deflate",
+};
+#else
+static struct ubifs_compressor zlib_compr = {
+	.compr_type = UBIFS_COMPR_ZLIB,
+	.name = "zlib",
+};
+#endif
+
+/* All UBIFS compressors */
+struct ubifs_compressor *ubifs_compressors[UBIFS_COMPR_TYPES_CNT];
+
+/**
+ * ubifs_compress - compress data.
+ * @in_buf: data to compress
+ * @in_len: length of the data to compress
+ * @out_buf: output buffer where compressed data should be stored
+ * @out_len: output buffer length is returned here
+ * @compr_type: type of compression to use on enter, actually used compression
+ *              type on exit
+ *
+ * This function compresses input buffer @in_buf of length @in_len and stores
+ * the result in the output buffer @out_buf and the resulting length in
+ * @out_len. If the input buffer does not compress, it is just copied to the
+ * @out_buf. The same happens if @compr_type is %UBIFS_COMPR_NONE or if
+ * compression error occurred.
+ *
+ * Note, if the input buffer was not compressed, it is copied to the output
+ * buffer and %UBIFS_COMPR_NONE is returned in @compr_type.
+ *
+ * This functions returns %0 on success or a negative error code on failure.
+ */
+void ubifs_compress(const void *in_buf, int in_len, void *out_buf, int *out_len,
+		    int *compr_type)
+{
+	int err;
+	struct ubifs_compressor *compr = ubifs_compressors[*compr_type];
+
+	if (*compr_type == UBIFS_COMPR_NONE)
+		goto no_compr;
+
+	/* If the input data is small, do not even try to compress it */
+	if (in_len < UBIFS_MIN_COMPR_LEN)
+		goto no_compr;
+
+	if (compr->comp_mutex)
+		mutex_lock(compr->comp_mutex);
+	err = crypto_comp_compress(compr->cc, in_buf, in_len, out_buf,
+				   out_len);
+	if (compr->comp_mutex)
+		mutex_unlock(compr->comp_mutex);
+	if (unlikely(err)) {
+		ubifs_warn("cannot compress %d bytes, compressor %s, "
+			   "error %d, leave data uncompressed",
+			   in_len, compr->name, err);
+		 goto no_compr;
+	}
+
+	/*
+	 * Presently, we just require that compression results in less data,
+	 * rather than any defined minimum compression ratio or amount.
+	 */
+	if (ALIGN(*out_len, 8) >= ALIGN(in_len, 8))
+		goto no_compr;
+
+	return;
+
+no_compr:
+	memcpy(out_buf, in_buf, in_len);
+	*out_len = in_len;
+	*compr_type = UBIFS_COMPR_NONE;
+}
+
+/**
+ * ubifs_decompress - decompress data.
+ * @in_buf: data to decompress
+ * @in_len: length of the data to decompress
+ * @out_buf: output buffer where decompressed data should
+ * @out_len: output length is returned here
+ * @compr_type: type of compression
+ *
+ * This function decompresses data from buffer @in_buf into buffer @out_buf.
+ * The length of the uncompressed data is returned in @out_len. This functions
+ * returns %0 on success or a negative error code on failure.
+ */
+int ubifs_decompress(const void *in_buf, int in_len, void *out_buf,
+		     int *out_len, int compr_type)
+{
+	int err;
+	struct ubifs_compressor *compr;
+
+	if (unlikely(compr_type < 0 || compr_type >= UBIFS_COMPR_TYPES_CNT)) {
+		ubifs_err("invalid compression type %d", compr_type);
+		return -EINVAL;
+	}
+
+	compr = ubifs_compressors[compr_type];
+
+	if (unlikely(!compr->capi_name)) {
+		ubifs_err("%s compression is not compiled in", compr->name);
+		return -EINVAL;
+	}
+
+	if (compr_type == UBIFS_COMPR_NONE) {
+		memcpy(out_buf, in_buf, in_len);
+		*out_len = in_len;
+		return 0;
+	}
+
+	if (compr->decomp_mutex)
+		mutex_lock(compr->decomp_mutex);
+	err = crypto_comp_decompress(compr->cc, in_buf, in_len, out_buf,
+				     out_len);
+	if (compr->decomp_mutex)
+		mutex_unlock(compr->decomp_mutex);
+	if (err)
+		ubifs_err("cannot decompress %d bytes, compressor %s, "
+			  "error %d", in_len, compr->name, err);
+
+	return err;
+}
+
+/**
+ * compr_init - initialize a compressor.
+ * @compr: compressor description object
+ *
+ * This function initializes the requested compressor and returns zero in case
+ * of success or a negative error code in case of failure.
+ */
+static int __init compr_init(struct ubifs_compressor *compr)
+{
+	if (compr->capi_name) {
+		compr->cc = crypto_alloc_comp(compr->capi_name, 0, 0);
+		if (IS_ERR(compr->cc)) {
+			ubifs_err("cannot initialize compressor %s, error %ld",
+				  compr->name, PTR_ERR(compr->cc));
+			return PTR_ERR(compr->cc);
+		}
+	}
+
+	ubifs_compressors[compr->compr_type] = compr;
+	return 0;
+}
+
+/**
+ * compr_exit - de-initialize a compressor.
+ * @compr: compressor description object
+ */
+static void compr_exit(struct ubifs_compressor *compr)
+{
+	if (compr->capi_name)
+		crypto_free_comp(compr->cc);
+	return;
+}
+
+/**
+ * ubifs_compressors_init - initialize UBIFS compressors.
+ *
+ * This function initializes the compressor which were compiled in. Returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+int __init ubifs_compressors_init(void)
+{
+	int err;
+
+	err = compr_init(&lzo_compr);
+	if (err)
+		return err;
+
+	err = compr_init(&zlib_compr);
+	if (err)
+		goto out_lzo;
+
+	ubifs_compressors[UBIFS_COMPR_NONE] = &none_compr;
+	return 0;
+
+out_lzo:
+	compr_exit(&lzo_compr);
+	return err;
+}
+
+/**
+ * ubifs_compressors_exit - de-initialize UBIFS compressors.
+ */
+void __exit ubifs_compressors_exit(void)
+{
+	compr_exit(&lzo_compr);
+	compr_exit(&zlib_compr);
+}

fs/ubifs/ioctl.c

+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation.
+ * Copyright (C) 2006, 2007 University of Szeged, Hungary
+ *
+ * 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: Zoltan Sogor
+ *          Artem Bityutskiy (Битюцкий Артём)
+ *          Adrian Hunter
+ */
+
+/* This file implements EXT2-compatible extended attribute ioctl() calls */
+
+#include <linux/compat.h>
+#include <linux/smp_lock.h>
+#include <linux/mount.h>
+#include "ubifs.h"
+
+/**
+ * ubifs_set_inode_flags - set VFS inode flags.
+ * @inode: VFS inode to set flags for
+ *
+ * This function propagates flags from UBIFS inode object to VFS inode object.
+ */
+void ubifs_set_inode_flags(struct inode *inode)
+{
+	unsigned int flags = ubifs_inode(inode)->flags;
+
+	inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_DIRSYNC);
+	if (flags & UBIFS_SYNC_FL)
+		inode->i_flags |= S_SYNC;
+	if (flags & UBIFS_APPEND_FL)
+		inode->i_flags |= S_APPEND;
+	if (flags & UBIFS_IMMUTABLE_FL)
+		inode->i_flags |= S_IMMUTABLE;
+	if (flags & UBIFS_DIRSYNC_FL)
+		inode->i_flags |= S_DIRSYNC;
+}
+
+/*
+ * ioctl2ubifs - convert ioctl inode flags to UBIFS inode flags.
+ * @ioctl_flags: flags to convert
+ *
+ * This function convert ioctl flags (@FS_COMPR_FL, etc) to UBIFS inode flags
+ * (@UBIFS_COMPR_FL, etc).
+ */
+static int ioctl2ubifs(int ioctl_flags)
+{
+	int ubifs_flags = 0;
+
+	if (ioctl_flags & FS_COMPR_FL)
+		ubifs_flags |= UBIFS_COMPR_FL;
+	if (ioctl_flags & FS_SYNC_FL)
+		ubifs_flags |= UBIFS_SYNC_FL;
+	if (ioctl_flags & FS_APPEND_FL)
+		ubifs_flags |= UBIFS_APPEND_FL;
+	if (ioctl_flags & FS_IMMUTABLE_FL)
+		ubifs_flags |= UBIFS_IMMUTABLE_FL;
+	if (ioctl_flags & FS_DIRSYNC_FL)
+		ubifs_flags |= UBIFS_DIRSYNC_FL;
+
+	return ubifs_flags;
+}
+
+/*
+ * ubifs2ioctl - convert UBIFS inode flags to ioctl inode flags.
+ * @ubifs_flags: flags to convert
+ *
+ * This function convert UBIFS (@UBIFS_COMPR_FL, etc) to ioctl flags
+ * (@FS_COMPR_FL, etc).
+ */
+static int ubifs2ioctl(int ubifs_flags)
+{
+	int ioctl_flags = 0;
+
+	if (ubifs_flags & UBIFS_COMPR_FL)
+		ioctl_flags |= FS_COMPR_FL;
+	if (ubifs_flags & UBIFS_SYNC_FL)
+		ioctl_flags |= FS_SYNC_FL;
+	if (ubifs_flags & UBIFS_APPEND_FL)
+		ioctl_flags |= FS_APPEND_FL;
+	if (ubifs_flags & UBIFS_IMMUTABLE_FL)
+		ioctl_flags |= FS_IMMUTABLE_FL;
+	if (ubifs_flags & UBIFS_DIRSYNC_FL)
+		ioctl_flags |= FS_DIRSYNC_FL;
+
+	return ioctl_flags;
+}
+
+static int setflags(struct inode *inode, int flags)
+{
+	int oldflags, err, release;
+	struct ubifs_inode *ui = ubifs_inode(inode);
+	struct ubifs_info *c = inode->i_sb->s_fs_info;
+	struct ubifs_budget_req req = { .dirtied_ino = 1,
+					.dirtied_ino_d = ui->data_len };
+
+	err = ubifs_budget_space(c, &req);
+	if (err)
+		return err;
+
+	/*
+	 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
+	 * the relevant capability.
+	 */
+	mutex_lock(&ui->ui_mutex);
+	oldflags = ubifs2ioctl(ui->flags);
+	if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) {
+		if (!capable(CAP_LINUX_IMMUTABLE)) {
+			err = -EPERM;
+			goto out_unlock;
+		}
+	}
+
+	ui->flags = ioctl2ubifs(flags);
+	ubifs_set_inode_flags(inode);
+	inode->i_ctime = ubifs_current_time(inode);
+	release = ui->dirty;
+	mark_inode_dirty_sync(inode);
+	mutex_unlock(&ui->ui_mutex);
+
+	if (release)
+		ubifs_release_budget(c, &req);
+	if (IS_SYNC(inode))
+		err = write_inode_now(inode, 1);
+	return err;
+
+out_unlock:
+	ubifs_err("can't modify inode %lu attributes", inode->i_ino);
+	mutex_unlock(&ui->ui_mutex);
+	ubifs_release_budget(c, &req);
+	return err;
+}
+
+long ubifs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	int flags, err;
+	struct inode *inode = file->f_path.dentry->d_inode;
+
+	switch (cmd) {
+	case FS_IOC_GETFLAGS:
+		flags = ubifs2ioctl(ubifs_inode(inode)->flags);
+
+		return put_user(flags, (int __user *) arg);
+
+	case FS_IOC_SETFLAGS: {
+		if (IS_RDONLY(inode))
+			return -EROFS;
+
+		if (!is_owner_or_cap(inode))
+			return -EACCES;
+
+		if (get_user(flags, (int __user *) arg))
+			return -EFAULT;
+
+		if (!S_ISDIR(inode->i_mode))
+			flags &= ~FS_DIRSYNC_FL;
+
+		/*
+		 * Make sure the file-system is read-write and make sure it
+		 * will not become read-only while we are changing the flags.
+		 */
+		err = mnt_want_write(file->f_path.mnt);
+		if (err)
+			return err;
+		err = setflags(inode, flags);
+		mnt_drop_write(file->f_path.mnt);
+		return err;
+	}
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+#ifdef CONFIG_COMPAT
+long ubifs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case FS_IOC32_GETFLAGS:
+		cmd = FS_IOC_GETFLAGS;
+		break;
+	case FS_IOC32_SETFLAGS:
+		cmd = FS_IOC_SETFLAGS;
+		break;
+	default:
+		return -ENOIOCTLCMD;
+	}
+	return ubifs_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif

include/linux/fs.h

@@ -1729,6 +1729,8 @@ static inline void invalidate_remote_inode(struct inode *inode)
 extern int invalidate_inode_pages2(struct address_space *mapping);
 extern int invalidate_inode_pages2_range(struct address_space *mapping,
 					 pgoff_t start, pgoff_t end);
+extern void generic_sync_sb_inodes(struct super_block *sb,
+				struct writeback_control *wbc);
 extern int write_inode_now(struct inode *, int);
 extern int filemap_fdatawrite(struct address_space *);
 extern int filemap_flush(struct address_space *);

init/do_mounts.c

@@ -372,7 +372,8 @@ void __init prepare_namespace(void)
 
 	if (saved_root_name[0]) {
 		root_device_name = saved_root_name;
-		if (!strncmp(root_device_name, "mtd", 3)) {
+		if (!strncmp(root_device_name, "mtd", 3) ||
+		    !strncmp(root_device_name, "ubi", 3)) {
 			mount_block_root(root_device_name, root_mountflags);
 			goto out;
 		}