mtd, ubi, ubifs: resync with Linux-3.14

resync ubi subsystem with linux:

commit 455c6fdbd219161bd09b1165f11699d6d73de11c
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Mar 30 20:40:15 2014 -0700

    Linux 3.14

A nice side effect of this, is we introduce UBI Fastmap support
to U-Boot.

Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Tom Rini <trini@ti.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Sergey Lapin <slapin@ossfans.org>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Joerg Krause <jkrause@posteo.de>

1 files changed, 866 insertions, 31 deletions

diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index aae5c65eaee..f87341e1087 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -4,18 +4,7 @@
  * 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
+ * SPDX-License-Identifier:	GPL-2.0+
  *
  * Authors: Artem Bityutskiy (Битюцкий Артём)
  *          Adrian Hunter
@@ -31,6 +20,26 @@
  * buffer is full or when it is not used for some time (by timer). This is
  * similar to the mechanism is used by JFFS2.
  *
+ * UBIFS distinguishes between minimum write size (@c->min_io_size) and maximum
+ * write size (@c->max_write_size). The latter is the maximum amount of bytes
+ * the underlying flash is able to program at a time, and writing in
+ * @c->max_write_size units should presumably be faster. Obviously,
+ * @c->min_io_size <= @c->max_write_size. Write-buffers are of
+ * @c->max_write_size bytes in size for maximum performance. However, when a
+ * write-buffer is flushed, only the portion of it (aligned to @c->min_io_size
+ * boundary) which contains data is written, not the whole write-buffer,
+ * because this is more space-efficient.
+ *
+ * This optimization adds few complications to the code. Indeed, on the one
+ * hand, we want to write in optimal @c->max_write_size bytes chunks, which
+ * also means aligning writes at the @c->max_write_size bytes offsets. On the
+ * other hand, we do not want to waste space when synchronizing the write
+ * buffer, so during synchronization we writes in smaller chunks. And this makes
+ * the next write offset to be not aligned to @c->max_write_size bytes. So the
+ * have to make sure that the write-buffer offset (@wbuf->offs) becomes aligned
+ * to @c->max_write_size bytes again. We do this by temporarily shrinking
+ * write-buffer size (@wbuf->size).
+ *
  * Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by
  * mutexes defined inside these objects. Since sometimes upper-level code
  * has to lock the write-buffer (e.g. journal space reservation code), many
@@ -46,10 +55,18 @@
  * UBIFS uses padding when it pads to the next min. I/O unit. In this case it
  * uses padding nodes or padding bytes, if the padding node does not fit.
  *
- * All UBIFS nodes are protected by CRC checksums and UBIFS checks all nodes
- * every time they are read from the flash media.
+ * All UBIFS nodes are protected by CRC checksums and UBIFS checks CRC when
+ * they are read from the flash media.
  */
 
+#define __UBOOT__
+#ifndef __UBOOT__
+#include <linux/crc32.h>
+#include <linux/slab.h>
+#else
+#include <linux/compat.h>
+#include <linux/err.h>
+#endif
 #include "ubifs.h"
 
 /**
@@ -59,12 +76,129 @@
  */
 void ubifs_ro_mode(struct ubifs_info *c, int err)
 {
-	if (!c->ro_media) {
-		c->ro_media = 1;
+	if (!c->ro_error) {
+		c->ro_error = 1;
 		c->no_chk_data_crc = 0;
+		c->vfs_sb->s_flags |= MS_RDONLY;
 		ubifs_warn("switched to read-only mode, error %d", err);
-		dbg_dump_stack();
+		dump_stack();
+	}
+}
+
+/*
+ * Below are simple wrappers over UBI I/O functions which include some
+ * additional checks and UBIFS debugging stuff. See corresponding UBI function
+ * for more information.
+ */
+
+int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
+		   int len, int even_ebadmsg)
+{
+	int err;
+
+	err = ubi_read(c->ubi, lnum, buf, offs, len);
+	/*
+	 * In case of %-EBADMSG print the error message only if the
+	 * @even_ebadmsg is true.
+	 */
+	if (err && (err != -EBADMSG || even_ebadmsg)) {
+		ubifs_err("reading %d bytes from LEB %d:%d failed, error %d",
+			  len, lnum, offs, err);
+		dump_stack();
+	}
+	return err;
+}
+
+int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
+		    int len)
+{
+	int err;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->ro_error)
+		return -EROFS;
+	if (!dbg_is_tst_rcvry(c))
+		err = ubi_leb_write(c->ubi, lnum, buf, offs, len);
+	else
+		err = dbg_leb_write(c, lnum, buf, offs, len);
+	if (err) {
+		ubifs_err("writing %d bytes to LEB %d:%d failed, error %d",
+			  len, lnum, offs, err);
+		ubifs_ro_mode(c, err);
+		dump_stack();
+	}
+	return err;
+}
+
+int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len)
+{
+	int err;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->ro_error)
+		return -EROFS;
+	if (!dbg_is_tst_rcvry(c))
+		err = ubi_leb_change(c->ubi, lnum, buf, len);
+	else
+		err = dbg_leb_change(c, lnum, buf, len);
+	if (err) {
+		ubifs_err("changing %d bytes in LEB %d failed, error %d",
+			  len, lnum, err);
+		ubifs_ro_mode(c, err);
+		dump_stack();
 	}
+	return err;
+}
+
+int ubifs_leb_unmap(struct ubifs_info *c, int lnum)
+{
+	int err;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->ro_error)
+		return -EROFS;
+	if (!dbg_is_tst_rcvry(c))
+		err = ubi_leb_unmap(c->ubi, lnum);
+	else
+		err = dbg_leb_unmap(c, lnum);
+	if (err) {
+		ubifs_err("unmap LEB %d failed, error %d", lnum, err);
+		ubifs_ro_mode(c, err);
+		dump_stack();
+	}
+	return err;
+}
+
+int ubifs_leb_map(struct ubifs_info *c, int lnum)
+{
+	int err;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->ro_error)
+		return -EROFS;
+	if (!dbg_is_tst_rcvry(c))
+		err = ubi_leb_map(c->ubi, lnum);
+	else
+		err = dbg_leb_map(c, lnum);
+	if (err) {
+		ubifs_err("mapping LEB %d failed, error %d", lnum, err);
+		ubifs_ro_mode(c, err);
+		dump_stack();
+	}
+	return err;
+}
+
+int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
+{
+	int err;
+
+	err = ubi_is_mapped(c->ubi, lnum);
+	if (err < 0) {
+		ubifs_err("ubi_is_mapped failed for LEB %d, error %d",
+			  lnum, err);
+		dump_stack();
+	}
+	return err;
 }
 
 /**
@@ -85,8 +219,12 @@ void ubifs_ro_mode(struct ubifs_info *c, int err)
  * This function may skip data nodes CRC checking if @c->no_chk_data_crc is
  * true, which is controlled by corresponding UBIFS mount option. However, if
  * @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is
- * checked. Similarly, if @c->always_chk_crc is true, @c->no_chk_data_crc is
- * ignored and CRC is checked.
+ * checked. Similarly, if @c->mounting or @c->remounting_rw is true (we are
+ * mounting or re-mounting to R/W mode), @c->no_chk_data_crc is ignored and CRC
+ * is checked. This is because during mounting or re-mounting from R/O mode to
+ * R/W mode we may read journal nodes (when replying the journal or doing the
+ * recovery) and the journal nodes may potentially be corrupted, so checking is
+ * required.
  *
  * This function returns zero in case of success and %-EUCLEAN in case of bad
  * CRC or magic.
@@ -128,8 +266,8 @@ int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
 		   node_len > c->ranges[type].max_len)
 		goto out_len;
 
-	if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->always_chk_crc &&
-	     c->no_chk_data_crc)
+	if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->mounting &&
+	    !c->remounting_rw && c->no_chk_data_crc)
 		return 0;
 
 	crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
@@ -150,8 +288,8 @@ out_len:
 out:
 	if (!quiet) {
 		ubifs_err("bad node at LEB %d:%d", lnum, offs);
-		dbg_dump_node(c, buf);
-		dbg_dump_stack();
+		ubifs_dump_node(c, buf);
+		dump_stack();
 	}
 	return err;
 }
@@ -257,6 +395,571 @@ void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
 }
 
 /**
+ * ubifs_prep_grp_node - prepare node of a group to be written to flash.
+ * @c: UBIFS file-system description object
+ * @node: the node to pad
+ * @len: node length
+ * @last: indicates the last node of the group
+ *
+ * This function prepares node at @node to be written to the media - it
+ * calculates node CRC and fills the common header.
+ */
+void ubifs_prep_grp_node(struct ubifs_info *c, void *node, int len, int last)
+{
+	uint32_t crc;
+	struct ubifs_ch *ch = node;
+	unsigned long long sqnum = next_sqnum(c);
+
+	ubifs_assert(len >= UBIFS_CH_SZ);
+
+	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
+	ch->len = cpu_to_le32(len);
+	if (last)
+		ch->group_type = UBIFS_LAST_OF_NODE_GROUP;
+	else
+		ch->group_type = UBIFS_IN_NODE_GROUP;
+	ch->sqnum = cpu_to_le64(sqnum);
+	ch->padding[0] = ch->padding[1] = 0;
+	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
+	ch->crc = cpu_to_le32(crc);
+}
+
+#ifndef __UBOOT__
+/**
+ * wbuf_timer_callback - write-buffer timer callback function.
+ * @data: timer data (write-buffer descriptor)
+ *
+ * This function is called when the write-buffer timer expires.
+ */
+static enum hrtimer_restart wbuf_timer_callback_nolock(struct hrtimer *timer)
+{
+	struct ubifs_wbuf *wbuf = container_of(timer, struct ubifs_wbuf, timer);
+
+	dbg_io("jhead %s", dbg_jhead(wbuf->jhead));
+	wbuf->need_sync = 1;
+	wbuf->c->need_wbuf_sync = 1;
+	ubifs_wake_up_bgt(wbuf->c);
+	return HRTIMER_NORESTART;
+}
+
+/**
+ * new_wbuf_timer - start new write-buffer timer.
+ * @wbuf: write-buffer descriptor
+ */
+static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
+{
+	ubifs_assert(!hrtimer_active(&wbuf->timer));
+
+	if (wbuf->no_timer)
+		return;
+	dbg_io("set timer for jhead %s, %llu-%llu millisecs",
+	       dbg_jhead(wbuf->jhead),
+	       div_u64(ktime_to_ns(wbuf->softlimit), USEC_PER_SEC),
+	       div_u64(ktime_to_ns(wbuf->softlimit) + wbuf->delta,
+		       USEC_PER_SEC));
+	hrtimer_start_range_ns(&wbuf->timer, wbuf->softlimit, wbuf->delta,
+			       HRTIMER_MODE_REL);
+}
+#endif
+
+/**
+ * cancel_wbuf_timer - cancel write-buffer timer.
+ * @wbuf: write-buffer descriptor
+ */
+static void cancel_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
+{
+	if (wbuf->no_timer)
+		return;
+	wbuf->need_sync = 0;
+#ifndef __UBOOT__
+	hrtimer_cancel(&wbuf->timer);
+#endif
+}
+
+/**
+ * ubifs_wbuf_sync_nolock - synchronize write-buffer.
+ * @wbuf: write-buffer to synchronize
+ *
+ * This function synchronizes write-buffer @buf and returns zero in case of
+ * success or a negative error code in case of failure.
+ *
+ * Note, although write-buffers are of @c->max_write_size, this function does
+ * not necessarily writes all @c->max_write_size bytes to the flash. Instead,
+ * if the write-buffer is only partially filled with data, only the used part
+ * of the write-buffer (aligned on @c->min_io_size boundary) is synchronized.
+ * This way we waste less space.
+ */
+int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
+{
+	struct ubifs_info *c = wbuf->c;
+	int err, dirt, sync_len;
+
+	cancel_wbuf_timer_nolock(wbuf);
+	if (!wbuf->used || wbuf->lnum == -1)
+		/* Write-buffer is empty or not seeked */
+		return 0;
+
+	dbg_io("LEB %d:%d, %d bytes, jhead %s",
+	       wbuf->lnum, wbuf->offs, wbuf->used, dbg_jhead(wbuf->jhead));
+	ubifs_assert(!(wbuf->avail & 7));
+	ubifs_assert(wbuf->offs + wbuf->size <= c->leb_size);
+	ubifs_assert(wbuf->size >= c->min_io_size);
+	ubifs_assert(wbuf->size <= c->max_write_size);
+	ubifs_assert(wbuf->size % c->min_io_size == 0);
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->leb_size - wbuf->offs >= c->max_write_size)
+		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
+
+	if (c->ro_error)
+		return -EROFS;
+
+	/*
+	 * Do not write whole write buffer but write only the minimum necessary
+	 * amount of min. I/O units.
+	 */
+	sync_len = ALIGN(wbuf->used, c->min_io_size);
+	dirt = sync_len - wbuf->used;
+	if (dirt)
+		ubifs_pad(c, wbuf->buf + wbuf->used, dirt);
+	err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, sync_len);
+	if (err)
+		return err;
+
+	spin_lock(&wbuf->lock);
+	wbuf->offs += sync_len;
+	/*
+	 * Now @wbuf->offs is not necessarily aligned to @c->max_write_size.
+	 * But our goal is to optimize writes and make sure we write in
+	 * @c->max_write_size chunks and to @c->max_write_size-aligned offset.
+	 * Thus, if @wbuf->offs is not aligned to @c->max_write_size now, make
+	 * sure that @wbuf->offs + @wbuf->size is aligned to
+	 * @c->max_write_size. This way we make sure that after next
+	 * write-buffer flush we are again at the optimal offset (aligned to
+	 * @c->max_write_size).
+	 */
+	if (c->leb_size - wbuf->offs < c->max_write_size)
+		wbuf->size = c->leb_size - wbuf->offs;
+	else if (wbuf->offs & (c->max_write_size - 1))
+		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
+	else
+		wbuf->size = c->max_write_size;
+	wbuf->avail = wbuf->size;
+	wbuf->used = 0;
+	wbuf->next_ino = 0;
+	spin_unlock(&wbuf->lock);
+
+	if (wbuf->sync_callback)
+		err = wbuf->sync_callback(c, wbuf->lnum,
+					  c->leb_size - wbuf->offs, dirt);
+	return err;
+}
+
+/**
+ * ubifs_wbuf_seek_nolock - seek write-buffer.
+ * @wbuf: write-buffer
+ * @lnum: logical eraseblock number to seek to
+ * @offs: logical eraseblock offset to seek to
+ *
+ * This function targets the write-buffer to logical eraseblock @lnum:@offs.
+ * The write-buffer has to be empty. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs)
+{
+	const struct ubifs_info *c = wbuf->c;
+
+	dbg_io("LEB %d:%d, jhead %s", lnum, offs, dbg_jhead(wbuf->jhead));
+	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt);
+	ubifs_assert(offs >= 0 && offs <= c->leb_size);
+	ubifs_assert(offs % c->min_io_size == 0 && !(offs & 7));
+	ubifs_assert(lnum != wbuf->lnum);
+	ubifs_assert(wbuf->used == 0);
+
+	spin_lock(&wbuf->lock);
+	wbuf->lnum = lnum;
+	wbuf->offs = offs;
+	if (c->leb_size - wbuf->offs < c->max_write_size)
+		wbuf->size = c->leb_size - wbuf->offs;
+	else if (wbuf->offs & (c->max_write_size - 1))
+		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
+	else
+		wbuf->size = c->max_write_size;
+	wbuf->avail = wbuf->size;
+	wbuf->used = 0;
+	spin_unlock(&wbuf->lock);
+
+	return 0;
+}
+
+#ifndef __UBOOT__
+/**
+ * ubifs_bg_wbufs_sync - synchronize write-buffers.
+ * @c: UBIFS file-system description object
+ *
+ * This function is called by background thread to synchronize write-buffers.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+int ubifs_bg_wbufs_sync(struct ubifs_info *c)
+{
+	int err, i;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (!c->need_wbuf_sync)
+		return 0;
+	c->need_wbuf_sync = 0;
+
+	if (c->ro_error) {
+		err = -EROFS;
+		goto out_timers;
+	}
+
+	dbg_io("synchronize");
+	for (i = 0; i < c->jhead_cnt; i++) {
+		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
+
+		cond_resched();
+
+		/*
+		 * If the mutex is locked then wbuf is being changed, so
+		 * synchronization is not necessary.
+		 */
+		if (mutex_is_locked(&wbuf->io_mutex))
+			continue;
+
+		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
+		if (!wbuf->need_sync) {
+			mutex_unlock(&wbuf->io_mutex);
+			continue;
+		}
+
+		err = ubifs_wbuf_sync_nolock(wbuf);
+		mutex_unlock(&wbuf->io_mutex);
+		if (err) {
+			ubifs_err("cannot sync write-buffer, error %d", err);
+			ubifs_ro_mode(c, err);
+			goto out_timers;
+		}
+	}
+
+	return 0;
+
+out_timers:
+	/* Cancel all timers to prevent repeated errors */
+	for (i = 0; i < c->jhead_cnt; i++) {
+		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
+
+		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
+		cancel_wbuf_timer_nolock(wbuf);
+		mutex_unlock(&wbuf->io_mutex);
+	}
+	return err;
+}
+
+/**
+ * ubifs_wbuf_write_nolock - write data to flash via write-buffer.
+ * @wbuf: write-buffer
+ * @buf: node to write
+ * @len: node length
+ *
+ * This function writes data to flash via write-buffer @wbuf. This means that
+ * the last piece of the node won't reach the flash media immediately if it
+ * does not take whole max. write unit (@c->max_write_size). Instead, the node
+ * will sit in RAM until the write-buffer is synchronized (e.g., by timer, or
+ * because more data are appended to the write-buffer).
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure. If the node cannot be written because there is no more
+ * space in this logical eraseblock, %-ENOSPC is returned.
+ */
+int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
+{
+	struct ubifs_info *c = wbuf->c;
+	int err, written, n, aligned_len = ALIGN(len, 8);
+
+	dbg_io("%d bytes (%s) to jhead %s wbuf at LEB %d:%d", len,
+	       dbg_ntype(((struct ubifs_ch *)buf)->node_type),
+	       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs + wbuf->used);
+	ubifs_assert(len > 0 && wbuf->lnum >= 0 && wbuf->lnum < c->leb_cnt);
+	ubifs_assert(wbuf->offs >= 0 && wbuf->offs % c->min_io_size == 0);
+	ubifs_assert(!(wbuf->offs & 7) && wbuf->offs <= c->leb_size);
+	ubifs_assert(wbuf->avail > 0 && wbuf->avail <= wbuf->size);
+	ubifs_assert(wbuf->size >= c->min_io_size);
+	ubifs_assert(wbuf->size <= c->max_write_size);
+	ubifs_assert(wbuf->size % c->min_io_size == 0);
+	ubifs_assert(mutex_is_locked(&wbuf->io_mutex));
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	ubifs_assert(!c->space_fixup);
+	if (c->leb_size - wbuf->offs >= c->max_write_size)
+		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
+
+	if (c->leb_size - wbuf->offs - wbuf->used < aligned_len) {
+		err = -ENOSPC;
+		goto out;
+	}
+
+	cancel_wbuf_timer_nolock(wbuf);
+
+	if (c->ro_error)
+		return -EROFS;
+
+	if (aligned_len <= wbuf->avail) {
+		/*
+		 * The node is not very large and fits entirely within
+		 * write-buffer.
+		 */
+		memcpy(wbuf->buf + wbuf->used, buf, len);
+
+		if (aligned_len == wbuf->avail) {
+			dbg_io("flush jhead %s wbuf to LEB %d:%d",
+			       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
+			err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf,
+					      wbuf->offs, wbuf->size);
+			if (err)
+				goto out;
+
+			spin_lock(&wbuf->lock);
+			wbuf->offs += wbuf->size;
+			if (c->leb_size - wbuf->offs >= c->max_write_size)
+				wbuf->size = c->max_write_size;
+			else
+				wbuf->size = c->leb_size - wbuf->offs;
+			wbuf->avail = wbuf->size;
+			wbuf->used = 0;
+			wbuf->next_ino = 0;
+			spin_unlock(&wbuf->lock);
+		} else {
+			spin_lock(&wbuf->lock);
+			wbuf->avail -= aligned_len;
+			wbuf->used += aligned_len;
+			spin_unlock(&wbuf->lock);
+		}
+
+		goto exit;
+	}
+
+	written = 0;
+
+	if (wbuf->used) {
+		/*
+		 * The node is large enough and does not fit entirely within
+		 * current available space. We have to fill and flush
+		 * write-buffer and switch to the next max. write unit.
+		 */
+		dbg_io("flush jhead %s wbuf to LEB %d:%d",
+		       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
+		memcpy(wbuf->buf + wbuf->used, buf, wbuf->avail);
+		err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs,
+				      wbuf->size);
+		if (err)
+			goto out;
+
+		wbuf->offs += wbuf->size;
+		len -= wbuf->avail;
+		aligned_len -= wbuf->avail;
+		written += wbuf->avail;
+	} else if (wbuf->offs & (c->max_write_size - 1)) {
+		/*
+		 * The write-buffer offset is not aligned to
+		 * @c->max_write_size and @wbuf->size is less than
+		 * @c->max_write_size. Write @wbuf->size bytes to make sure the
+		 * following writes are done in optimal @c->max_write_size
+		 * chunks.
+		 */
+		dbg_io("write %d bytes to LEB %d:%d",
+		       wbuf->size, wbuf->lnum, wbuf->offs);
+		err = ubifs_leb_write(c, wbuf->lnum, buf, wbuf->offs,
+				      wbuf->size);
+		if (err)
+			goto out;
+
+		wbuf->offs += wbuf->size;
+		len -= wbuf->size;
+		aligned_len -= wbuf->size;
+		written += wbuf->size;
+	}
+
+	/*
+	 * The remaining data may take more whole max. write units, so write the
+	 * remains multiple to max. write unit size directly to the flash media.
+	 * We align node length to 8-byte boundary because we anyway flash wbuf
+	 * if the remaining space is less than 8 bytes.
+	 */
+	n = aligned_len >> c->max_write_shift;
+	if (n) {
+		n <<= c->max_write_shift;
+		dbg_io("write %d bytes to LEB %d:%d", n, wbuf->lnum,
+		       wbuf->offs);
+		err = ubifs_leb_write(c, wbuf->lnum, buf + written,
+				      wbuf->offs, n);
+		if (err)
+			goto out;
+		wbuf->offs += n;
+		aligned_len -= n;
+		len -= n;
+		written += n;
+	}
+
+	spin_lock(&wbuf->lock);
+	if (aligned_len)
+		/*
+		 * And now we have what's left and what does not take whole
+		 * max. write unit, so write it to the write-buffer and we are
+		 * done.
+		 */
+		memcpy(wbuf->buf, buf + written, len);
+
+	if (c->leb_size - wbuf->offs >= c->max_write_size)
+		wbuf->size = c->max_write_size;
+	else
+		wbuf->size = c->leb_size - wbuf->offs;
+	wbuf->avail = wbuf->size - aligned_len;
+	wbuf->used = aligned_len;
+	wbuf->next_ino = 0;
+	spin_unlock(&wbuf->lock);
+
+exit:
+	if (wbuf->sync_callback) {
+		int free = c->leb_size - wbuf->offs - wbuf->used;
+
+		err = wbuf->sync_callback(c, wbuf->lnum, free, 0);
+		if (err)
+			goto out;
+	}
+
+	if (wbuf->used)
+		new_wbuf_timer_nolock(wbuf);
+
+	return 0;
+
+out:
+	ubifs_err("cannot write %d bytes to LEB %d:%d, error %d",
+		  len, wbuf->lnum, wbuf->offs, err);
+	ubifs_dump_node(c, buf);
+	dump_stack();
+	ubifs_dump_leb(c, wbuf->lnum);
+	return err;
+}
+
+/**
+ * ubifs_write_node - write node to the media.
+ * @c: UBIFS file-system description object
+ * @buf: the node to write
+ * @len: node length
+ * @lnum: logical eraseblock number
+ * @offs: offset within the logical eraseblock
+ *
+ * This function automatically fills node magic number, assigns sequence
+ * number, and calculates node CRC checksum. The length of the @buf buffer has
+ * to be aligned to the minimal I/O unit size. This function automatically
+ * appends padding node and padding bytes if needed. Returns zero in case of
+ * success and a negative error code in case of failure.
+ */
+int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
+		     int offs)
+{
+	int err, buf_len = ALIGN(len, c->min_io_size);
+
+	dbg_io("LEB %d:%d, %s, length %d (aligned %d)",
+	       lnum, offs, dbg_ntype(((struct ubifs_ch *)buf)->node_type), len,
+	       buf_len);
+	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
+	ubifs_assert(offs % c->min_io_size == 0 && offs < c->leb_size);
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	ubifs_assert(!c->space_fixup);
+
+	if (c->ro_error)
+		return -EROFS;
+
+	ubifs_prepare_node(c, buf, len, 1);
+	err = ubifs_leb_write(c, lnum, buf, offs, buf_len);
+	if (err)
+		ubifs_dump_node(c, buf);
+
+	return err;
+}
+#endif
+
+/**
+ * ubifs_read_node_wbuf - read node from the media or write-buffer.
+ * @wbuf: wbuf to check for un-written data
+ * @buf: buffer to read to
+ * @type: node type
+ * @len: node length
+ * @lnum: logical eraseblock number
+ * @offs: offset within the logical eraseblock
+ *
+ * This function reads a node of known type and length, checks it and stores
+ * in @buf. If the node partially or fully sits in the write-buffer, this
+ * function takes data from the buffer, otherwise it reads the flash media.
+ * Returns zero in case of success, %-EUCLEAN if CRC mismatched and a negative
+ * error code in case of failure.
+ */
+int ubifs_read_node_wbuf(struct ubifs_wbuf *wbuf, void *buf, int type, int len,
+			 int lnum, int offs)
+{
+	const struct ubifs_info *c = wbuf->c;
+	int err, rlen, overlap;
+	struct ubifs_ch *ch = buf;
+
+	dbg_io("LEB %d:%d, %s, length %d, jhead %s", lnum, offs,
+	       dbg_ntype(type), len, dbg_jhead(wbuf->jhead));
+	ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
+	ubifs_assert(!(offs & 7) && offs < c->leb_size);
+	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
+
+	spin_lock(&wbuf->lock);
+	overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
+	if (!overlap) {
+		/* We may safely unlock the write-buffer and read the data */
+		spin_unlock(&wbuf->lock);
+		return ubifs_read_node(c, buf, type, len, lnum, offs);
+	}
+
+	/* Don't read under wbuf */
+	rlen = wbuf->offs - offs;
+	if (rlen < 0)
+		rlen = 0;
+
+	/* Copy the rest from the write-buffer */
+	memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
+	spin_unlock(&wbuf->lock);
+
+	if (rlen > 0) {
+		/* Read everything that goes before write-buffer */
+		err = ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
+		if (err && err != -EBADMSG)
+			return err;
+	}
+
+	if (type != ch->node_type) {
+		ubifs_err("bad node type (%d but expected %d)",
+			  ch->node_type, type);
+		goto out;
+	}
+
+	err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
+	if (err) {
+		ubifs_err("expected node type %d", type);
+		return err;
+	}
+
+	rlen = le32_to_cpu(ch->len);
+	if (rlen != len) {
+		ubifs_err("bad node length %d, expected %d", rlen, len);
+		goto out;
+	}
+
+	return 0;
+
+out:
+	ubifs_err("bad node at LEB %d:%d", lnum, offs);
+	ubifs_dump_node(c, buf);
+	dump_stack();
+	return -EINVAL;
+}
+
+/**
  * ubifs_read_node - read node.
  * @c: UBIFS file-system description object
  * @buf: buffer to read to
@@ -281,12 +984,9 @@ int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
 	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
 
-	err = ubi_read(c->ubi, lnum, buf, offs, len);
-	if (err && err != -EBADMSG) {
-		ubifs_err("cannot read node %d from LEB %d:%d, error %d",
-			  type, lnum, offs, err);
+	err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
+	if (err && err != -EBADMSG)
 		return err;
-	}
 
 	if (type != ch->node_type) {
 		ubifs_err("bad node type (%d but expected %d)",
@@ -309,8 +1009,143 @@ int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
 	return 0;
 
 out:
-	ubifs_err("bad node at LEB %d:%d", lnum, offs);
-	dbg_dump_node(c, buf);
-	dbg_dump_stack();
+	ubifs_err("bad node at LEB %d:%d, LEB mapping status %d", lnum, offs,
+		  ubi_is_mapped(c->ubi, lnum));
+	ubifs_dump_node(c, buf);
+	dump_stack();
 	return -EINVAL;
 }
+
+/**
+ * ubifs_wbuf_init - initialize write-buffer.
+ * @c: UBIFS file-system description object
+ * @wbuf: write-buffer to initialize
+ *
+ * This function initializes write-buffer. Returns zero in case of success
+ * %-ENOMEM in case of failure.
+ */
+int ubifs_wbuf_init(struct ubifs_info *c, struct ubifs_wbuf *wbuf)
+{
+	size_t size;
+
+	wbuf->buf = kmalloc(c->max_write_size, GFP_KERNEL);
+	if (!wbuf->buf)
+		return -ENOMEM;
+
+	size = (c->max_write_size / UBIFS_CH_SZ + 1) * sizeof(ino_t);
+	wbuf->inodes = kmalloc(size, GFP_KERNEL);
+	if (!wbuf->inodes) {
+		kfree(wbuf->buf);
+		wbuf->buf = NULL;
+		return -ENOMEM;
+	}
+
+	wbuf->used = 0;
+	wbuf->lnum = wbuf->offs = -1;
+	/*
+	 * If the LEB starts at the max. write size aligned address, then
+	 * write-buffer size has to be set to @c->max_write_size. Otherwise,
+	 * set it to something smaller so that it ends at the closest max.
+	 * write size boundary.
+	 */
+	size = c->max_write_size - (c->leb_start % c->max_write_size);
+	wbuf->avail = wbuf->size = size;
+	wbuf->sync_callback = NULL;
+	mutex_init(&wbuf->io_mutex);
+	spin_lock_init(&wbuf->lock);
+	wbuf->c = c;
+	wbuf->next_ino = 0;
+
+#ifndef __UBOOT__
+	hrtimer_init(&wbuf->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	wbuf->timer.function = wbuf_timer_callback_nolock;
+	wbuf->softlimit = ktime_set(WBUF_TIMEOUT_SOFTLIMIT, 0);
+	wbuf->delta = WBUF_TIMEOUT_HARDLIMIT - WBUF_TIMEOUT_SOFTLIMIT;
+	wbuf->delta *= 1000000000ULL;
+	ubifs_assert(wbuf->delta <= ULONG_MAX);
+#endif
+	return 0;
+}
+
+/**
+ * ubifs_wbuf_add_ino_nolock - add an inode number into the wbuf inode array.
+ * @wbuf: the write-buffer where to add
+ * @inum: the inode number
+ *
+ * This function adds an inode number to the inode array of the write-buffer.
+ */
+void ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf *wbuf, ino_t inum)
+{
+	if (!wbuf->buf)
+		/* NOR flash or something similar */
+		return;
+
+	spin_lock(&wbuf->lock);
+	if (wbuf->used)
+		wbuf->inodes[wbuf->next_ino++] = inum;
+	spin_unlock(&wbuf->lock);
+}
+
+/**
+ * wbuf_has_ino - returns if the wbuf contains data from the inode.
+ * @wbuf: the write-buffer
+ * @inum: the inode number
+ *
+ * This function returns with %1 if the write-buffer contains some data from the
+ * given inode otherwise it returns with %0.
+ */
+static int wbuf_has_ino(struct ubifs_wbuf *wbuf, ino_t inum)
+{
+	int i, ret = 0;
+
+	spin_lock(&wbuf->lock);
+	for (i = 0; i < wbuf->next_ino; i++)
+		if (inum == wbuf->inodes[i]) {
+			ret = 1;
+			break;
+		}
+	spin_unlock(&wbuf->lock);
+
+	return ret;
+}
+
+/**
+ * ubifs_sync_wbufs_by_inode - synchronize write-buffers for an inode.
+ * @c: UBIFS file-system description object
+ * @inode: inode to synchronize
+ *
+ * This function synchronizes write-buffers which contain nodes belonging to
+ * @inode. Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+int ubifs_sync_wbufs_by_inode(struct ubifs_info *c, struct inode *inode)
+{
+	int i, err = 0;
+
+	for (i = 0; i < c->jhead_cnt; i++) {
+		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
+
+		if (i == GCHD)
+			/*
+			 * GC head is special, do not look at it. Even if the
+			 * head contains something related to this inode, it is
+			 * a _copy_ of corresponding on-flash node which sits
+			 * somewhere else.
+			 */
+			continue;
+
+		if (!wbuf_has_ino(wbuf, inode->i_ino))
+			continue;
+
+		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
+		if (wbuf_has_ino(wbuf, inode->i_ino))
+			err = ubifs_wbuf_sync_nolock(wbuf);
+		mutex_unlock(&wbuf->io_mutex);
+
+		if (err) {
+			ubifs_ro_mode(c, err);
+			return err;
+		}
+	}
+	return 0;
+}