diff --git a/drivers/staging/pohmelfs/trans.c b/drivers/staging/pohmelfs/trans.c
new file mode 100644
index 0000000..3f9225e
--- /dev/null
+++ b/drivers/staging/pohmelfs/trans.c
@@ -0,0 +1,715 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/crypto.h>
+#include <linux/fs.h>
+#include <linux/jhash.h>
+#include <linux/hash.h>
+#include <linux/ktime.h>
+#include <linux/mempool.h>
+#include <linux/mm.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/parser.h>
+#include <linux/poll.h>
+#include <linux/swap.h>
+#include <linux/slab.h>
+#include <linux/statfs.h>
+#include <linux/writeback.h>
+
+#include "netfs.h"
+
+static struct kmem_cache *netfs_trans_dst;
+static mempool_t *netfs_trans_dst_pool;
+
+static void netfs_trans_init_static(struct netfs_trans *t, int num, int size)
+{
+	t->page_num = num;
+	t->total_size = size;
+	atomic_set(&t->refcnt, 1);
+
+	spin_lock_init(&t->dst_lock);
+	INIT_LIST_HEAD(&t->dst_list);
+}
+
+static int netfs_trans_send_pages(struct netfs_trans *t, struct netfs_state *st)
+{
+	int err = 0;
+	unsigned int i, attached_pages = t->attached_pages, ci;
+	struct msghdr msg;
+	struct page **pages = (t->eng)?t->eng->pages:t->pages;
+	struct page *p;
+	unsigned int size;
+
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags = MSG_WAITALL | MSG_MORE;
+
+	ci = 0;
+	for (i=0; i<t->page_num; ++i) {
+		struct page *page = pages[ci];
+		struct netfs_cmd cmd;
+		struct iovec io;
+
+		p = t->pages[i];
+
+		if (!p)
+			continue;
+
+		size = page_private(p);
+
+		io.iov_base = &cmd;
+		io.iov_len = sizeof(struct netfs_cmd);
+
+		cmd.cmd = NETFS_WRITE_PAGE;
+		cmd.ext = 0;
+		cmd.id = 0;
+		cmd.size = size;
+		cmd.start = p->index;
+		cmd.start <<= PAGE_CACHE_SHIFT;
+		cmd.csize = 0;
+		cmd.cpad = 0;
+		cmd.iv = pohmelfs_gen_iv(t);
+
+		netfs_convert_cmd(&cmd);
+
+		msg.msg_iov = &io;
+		msg.msg_iovlen = 1;
+		msg.msg_flags = MSG_WAITALL | MSG_MORE;
+
+		err = kernel_sendmsg(st->socket, &msg, (struct kvec *)msg.msg_iov, 1, sizeof(struct netfs_cmd));
+		if (err <= 0) {
+			printk("%s: %d/%d failed to send transaction header: t: %p, gen: %u, err: %d.\n",
+					__func__, i, t->page_num, t, t->gen, err);
+			if (err == 0)
+				err = -ECONNRESET;
+			goto err_out;
+		}
+
+		msg.msg_flags = MSG_WAITALL|(attached_pages == 1)?0:MSG_MORE;
+
+		err = kernel_sendpage(st->socket, page, 0, size, msg.msg_flags);
+		if (err <= 0) {
+			printk("%s: %d/%d failed to send transaction page: t: %p, gen: %u, size: %u, err: %d.\n",
+					__func__, i, t->page_num, t, t->gen, size, err);
+			if (err == 0)
+				err = -ECONNRESET;
+			goto err_out;
+		}
+
+		dprintk("%s: %d/%d sent t: %p, gen: %u, page: %p/%p, size: %u.\n",
+			__func__, i, t->page_num, t, t->gen, page, p, size);
+
+		err = 0;
+		attached_pages--;
+		if (!attached_pages)
+			break;
+		ci++;
+
+		continue;
+
+err_out:
+		printk("%s: t: %p, gen: %u, err: %d.\n", __func__, t, t->gen, err);
+		netfs_state_exit(st);
+		break;
+	}
+
+	return err;
+}
+
+int netfs_trans_send(struct netfs_trans *t, struct netfs_state *st)
+{
+	int err;
+	struct msghdr msg;
+
+	BUG_ON(!t->iovec.iov_len);
+	BUG_ON(t->iovec.iov_len > 1024*1024*1024);
+
+	netfs_state_lock_send(st);
+	if (!st->socket) {
+		err = netfs_state_init(st);
+		if (err)
+			goto err_out_unlock_return;
+	}
+
+	msg.msg_iov = &t->iovec;
+	msg.msg_iovlen = 1;
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags = MSG_WAITALL;
+
+	if (t->attached_pages)
+		msg.msg_flags |= MSG_MORE;
+
+	err = kernel_sendmsg(st->socket, &msg, (struct kvec *)msg.msg_iov, 1, t->iovec.iov_len);
+	if (err <= 0) {
+		printk("%s: failed to send contig transaction: t: %p, gen: %u, size: %u, err: %d.\n",
+				__func__, t, t->gen, t->iovec.iov_len, err);
+		if (err == 0)
+			err = -ECONNRESET;
+		goto err_out_unlock_return;
+	}
+
+	dprintk("%s: sent %s transaction: t: %p, gen: %u, size: %u, page_num: %u.\n",
+			__func__, (t->page_num)?"partial":"full",
+			t, t->gen, t->iovec.iov_len, t->page_num);
+
+	err = 0;
+	if (t->attached_pages)
+		err = netfs_trans_send_pages(t, st);
+
+err_out_unlock_return:
+
+	if (st->need_reset) {
+		netfs_state_exit(st);
+	}
+	netfs_state_unlock_send(st);
+
+	dprintk("%s: t: %p, gen: %u, err: %d.\n",
+		__func__, t, t->gen, err);
+
+	t->result = err;
+	return err;
+}
+
+static inline int netfs_trans_cmp(unsigned int gen, unsigned int new)
+{
+	if (gen < new)
+		return 1;
+	if (gen > new)
+		return -1;
+	return 0;
+}
+
+struct netfs_trans_dst *netfs_trans_search(struct netfs_state *st, unsigned int gen)
+{
+	struct rb_root *root = &st->trans_root;
+	struct rb_node *n = root->rb_node;
+	struct netfs_trans_dst *tmp, *ret = NULL;
+	struct netfs_trans *t;
+	int cmp;
+
+	while (n) {
+		tmp = rb_entry(n, struct netfs_trans_dst, state_entry);
+		t = tmp->trans;
+
+		cmp = netfs_trans_cmp(t->gen, gen);
+		if (cmp < 0)
+			n = n->rb_left;
+		else if (cmp > 0)
+			n = n->rb_right;
+		else {
+			ret = tmp;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static int netfs_trans_insert(struct netfs_trans_dst *ndst, struct netfs_state *st)
+{
+	struct rb_root *root = &st->trans_root;
+	struct rb_node **n = &root->rb_node, *parent = NULL;
+	struct netfs_trans_dst *ret = NULL, *tmp;
+	struct netfs_trans *t = NULL, *new = ndst->trans;
+	int cmp;
+
+	while (*n) {
+		parent = *n;
+
+		tmp = rb_entry(parent, struct netfs_trans_dst, state_entry);
+		t = tmp->trans;
+
+		cmp = netfs_trans_cmp(t->gen, new->gen);
+		if (cmp < 0)
+			n = &parent->rb_left;
+		else if (cmp > 0)
+			n = &parent->rb_right;
+		else {
+			ret = tmp;
+			break;
+		}
+	}
+
+	if (ret) {
+		printk("%s: exist: old: gen: %u, flags: %x, send_time: %lu, "
+				"new: gen: %u, flags: %x, send_time: %lu.\n",
+			__func__, t->gen, t->flags, ret->send_time,
+			new->gen, new->flags, ndst->send_time);
+		return -EEXIST;
+	}
+
+	rb_link_node(&ndst->state_entry, parent, n);
+	rb_insert_color(&ndst->state_entry, root);
+	ndst->send_time = jiffies;
+
+	return 0;
+}
+
+int netfs_trans_remove_nolock(struct netfs_trans_dst *dst, struct netfs_state *st)
+{
+	if (dst && dst->state_entry.rb_parent_color) {
+		rb_erase(&dst->state_entry, &st->trans_root);
+		dst->state_entry.rb_parent_color = 0;
+		return 1;
+	}
+	return 0;
+}
+
+static int netfs_trans_remove_state(struct netfs_trans_dst *dst)
+{
+	int ret;
+	struct netfs_state *st = dst->state;
+
+	mutex_lock(&st->trans_lock);
+	ret = netfs_trans_remove_nolock(dst, st);
+	mutex_unlock(&st->trans_lock);
+
+	return ret;
+}
+
+/*
+ * Create new destination for given transaction associated with given network state.
+ * Transaction's reference counter is bumped and will be dropped when either
+ * reply is received or when async timeout detection task will fail resending
+ * and drop transaction.
+ */
+static int netfs_trans_push_dst(struct netfs_trans *t, struct netfs_state *st)
+{
+	struct netfs_trans_dst *dst;
+	int err;
+
+	dst = mempool_alloc(netfs_trans_dst_pool, GFP_KERNEL);
+	if (!dst)
+		return -ENOMEM;
+
+	dst->retries = 0;
+	dst->send_time = 0;
+	dst->state = st;
+	dst->trans = t;
+	netfs_trans_get(t);
+
+	mutex_lock(&st->trans_lock);
+	err = netfs_trans_insert(dst, st);
+	mutex_unlock(&st->trans_lock);
+
+	if (err)
+		goto err_out_free;
+
+	spin_lock(&t->dst_lock);
+	list_add_tail(&dst->trans_entry, &t->dst_list);
+	spin_unlock(&t->dst_lock);
+
+	return 0;
+
+err_out_free:
+	t->result = err;
+	netfs_trans_put(t);
+	mempool_free(dst, netfs_trans_dst_pool);
+	return err;
+}
+
+static void netfs_trans_free_dst(struct netfs_trans_dst *dst)
+{
+	netfs_trans_put(dst->trans);
+	mempool_free(dst, netfs_trans_dst_pool);
+}
+
+static void netfs_trans_remove_dst(struct netfs_trans_dst *dst)
+{
+	if (netfs_trans_remove_state(dst))
+		netfs_trans_free_dst(dst);
+}
+
+/*
+ * Drop destination transaction entry when we know it.
+ */
+void netfs_trans_drop_dst(struct netfs_trans_dst *dst)
+{
+	struct netfs_trans *t = dst->trans;
+
+	spin_lock(&t->dst_lock);
+	list_del_init(&dst->trans_entry);
+	spin_unlock(&t->dst_lock);
+
+	netfs_trans_remove_dst(dst);
+}
+
+/*
+ * Drop destination transaction entry when we know it and when we
+ * already removed dst from state tree.
+ */
+void netfs_trans_drop_dst_nostate(struct netfs_trans_dst *dst)
+{
+	struct netfs_trans *t = dst->trans;
+
+	spin_lock(&t->dst_lock);
+	list_del_init(&dst->trans_entry);
+	spin_unlock(&t->dst_lock);
+	
+	netfs_trans_free_dst(dst);
+}
+
+/*
+ * This drops destination transaction entry from appropriate network state
+ * tree and drops related reference counter. It is possible that transaction
+ * will be freed here if its reference counter hits zero.
+ * Destination transaction entry will be freed.
+ */
+void netfs_trans_drop_trans(struct netfs_trans *t, struct netfs_state *st)
+{
+	struct netfs_trans_dst *dst, *tmp, *ret = NULL;
+
+	spin_lock(&t->dst_lock);
+	list_for_each_entry_safe(dst, tmp, &t->dst_list, trans_entry) {
+		if (dst->state == st) {
+			ret = dst;
+			list_del(&dst->trans_entry);
+			break;
+		}
+	}
+	spin_unlock(&t->dst_lock);
+
+	if (ret)
+		netfs_trans_remove_dst(ret);
+}
+
+/*
+ * This drops destination transaction entry from appropriate network state
+ * tree and drops related reference counter. It is possible that transaction
+ * will be freed here if its reference counter hits zero.
+ * Destination transaction entry will be freed.
+ */
+void netfs_trans_drop_last(struct netfs_trans *t, struct netfs_state *st)
+{
+	struct netfs_trans_dst *dst, *tmp, *ret;
+
+	spin_lock(&t->dst_lock);
+	ret = list_entry(t->dst_list.prev, struct netfs_trans_dst, trans_entry);
+	if (ret->state != st) {
+		ret = NULL;
+		list_for_each_entry_safe(dst, tmp, &t->dst_list, trans_entry) {
+			if (dst->state == st) {
+				ret = dst;
+				list_del_init(&dst->trans_entry);
+				break;
+			}
+		}
+	} else {
+		list_del(&ret->trans_entry);
+	}
+	spin_unlock(&t->dst_lock);
+
+	if (ret)
+		netfs_trans_remove_dst(ret);
+}
+
+static int netfs_trans_push(struct netfs_trans *t, struct netfs_state *st)
+{
+	int err;
+
+	err = netfs_trans_push_dst(t, st);
+	if (err)
+		return err;
+
+	err = netfs_trans_send(t, st);
+	if (err)
+		goto err_out_free;
+
+	if (t->flags & NETFS_TRANS_SINGLE_DST)
+		pohmelfs_switch_active(st->psb);
+
+	return 0;
+
+err_out_free:
+	t->result = err;
+	netfs_trans_drop_last(t, st);
+
+	return err;
+}
+
+int netfs_trans_finish_send(struct netfs_trans *t, struct pohmelfs_sb *psb)
+{
+	struct pohmelfs_config *c;
+	int err = -ENODEV;
+	struct netfs_state *st;
+#if 0
+	dprintk("%s: t: %p, gen: %u, size: %u, page_num: %u, active: %p.\n",
+		__func__, t, t->gen, t->iovec.iov_len, t->page_num, psb->active_state);
+#endif
+	mutex_lock(&psb->state_lock);
+
+	if ((t->flags & NETFS_TRANS_SINGLE_DST) && psb->active_state) {
+		st = &psb->active_state->state;
+
+		err = -EPIPE;
+		if (netfs_state_poll(st) & POLLOUT) {
+			err = netfs_trans_push_dst(t, st);
+			if (!err) {
+				err = netfs_trans_send(t, st);
+				if (err) {
+					netfs_trans_drop_last(t, st);
+				} else {
+					pohmelfs_switch_active(psb);
+					goto out;
+				}
+			}
+		}
+		pohmelfs_switch_active(psb);
+	}
+
+	list_for_each_entry(c, &psb->state_list, config_entry) {
+		st = &c->state;
+
+		err = netfs_trans_push(t, st);
+		if (!err && (t->flags & NETFS_TRANS_SINGLE_DST))
+			break;
+	}
+out:
+	mutex_unlock(&psb->state_lock);
+#if 0
+	dprintk("%s: fully sent t: %p, gen: %u, size: %u, page_num: %u, err: %d.\n",
+		__func__, t, t->gen, t->iovec.iov_len, t->page_num, err);
+#endif
+	if (err)
+		t->result = err;
+	return err;
+}
+
+int netfs_trans_finish(struct netfs_trans *t, struct pohmelfs_sb *psb)
+{
+	int err;
+	struct netfs_cmd *cmd = t->iovec.iov_base;
+
+	t->gen = atomic_inc_return(&psb->trans_gen);
+
+	pohmelfs_ftrans_clean(t->gen);
+
+	cmd->size = t->iovec.iov_len - sizeof(struct netfs_cmd) +
+		t->attached_size + t->attached_pages * sizeof(struct netfs_cmd);
+	cmd->cmd = NETFS_TRANS;
+	cmd->start = t->gen;
+	cmd->id = 0;
+
+	if (psb->perform_crypto) {
+		cmd->ext = psb->crypto_attached_size;
+		cmd->csize = psb->crypto_attached_size;
+	}
+
+	dprintk("%s: t: %u, size: %u, iov_len: %u, attached_size: %u, attached_pages: %u.\n",
+			__func__, t->gen, cmd->size, t->iovec.iov_len, t->attached_size, t->attached_pages);
+	err = pohmelfs_trans_crypt(t, psb);
+	if (err) {
+		t->result = err;
+		netfs_convert_cmd(cmd);
+		dprintk("%s: trans: %llu, crypto_attached_size: %u, attached_size: %u, attached_pages: %d, trans_size: %u, err: %d.\n",
+			__func__, cmd->start, psb->crypto_attached_size, t->attached_size, t->attached_pages, cmd->size, err);
+	}
+	netfs_trans_put(t);
+	return err;
+}
+
+/*
+ * Resend transaction to remote server(s).
+ * If new servers were added into superblock, we can try to send data
+ * to them too.
+ *
+ * It is called under superblock's state_lock, so we can safely
+ * dereference psb->state_list. Also, transaction's reference counter is
+ * bumped, so it can not go away under us, thus we can safely access all
+ * its members. State is locked.
+ *
+ * This function returns 0 if transaction was successfully sent to at
+ * least one destination target. 
+ */
+int netfs_trans_resend(struct netfs_trans *t, struct pohmelfs_sb *psb)
+{
+	struct netfs_trans_dst *dst;
+	struct netfs_state *st;
+	struct pohmelfs_config *c;
+	int err, exist, error = -ENODEV;
+
+	list_for_each_entry(c, &psb->state_list, config_entry) {
+		st = &c->state;
+
+		exist = 0;
+		spin_lock(&t->dst_lock);
+		list_for_each_entry(dst, &t->dst_list, trans_entry) {
+			if (st == dst->state) {
+				exist = 1;
+				break;
+			}
+		}
+		spin_unlock(&t->dst_lock);
+
+		if (exist) {
+			if (!(t->flags & NETFS_TRANS_SINGLE_DST) ||
+					(c->config_entry.next == &psb->state_list)) {
+				dprintk("%s: resending st: %p, t: %p, gen: %u.\n",
+						__func__, st, t, t->gen);
+				err = netfs_trans_send(t, st);
+				if (!err)
+					error = 0;
+			}
+			continue;
+		}
+
+		dprintk("%s: pushing/resending st: %p, t: %p, gen: %u.\n",
+				__func__, st, t, t->gen);
+		err = netfs_trans_push(t, st);
+		if (err)
+			continue;
+		error = 0;
+		if (t->flags & NETFS_TRANS_SINGLE_DST)
+			break;
+	}
+
+	t->result = error;
+	return error;
+}
+
+void *netfs_trans_add(struct netfs_trans *t, unsigned int size)
+{
+	struct iovec *io = &t->iovec;
+	void *ptr;
+
+	if (size > t->total_size) {
+		ptr = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	if (io->iov_len + size > t->total_size) {
+		dprintk("%s: too big size t: %p, gen: %u, iov_len: %u, size: %u, total: %u.\n",
+				__func__, t, t->gen, io->iov_len, size, t->total_size);
+		ptr = ERR_PTR(-E2BIG);
+		goto out;
+	}
+
+	ptr = io->iov_base + io->iov_len;
+	io->iov_len += size;
+
+out:
+	dprintk("%s: t: %p, gen: %u, size: %u, total: %u.\n",
+		__func__, t, t->gen, size, io->iov_len);
+	return ptr;
+}
+
+void netfs_trans_free(struct netfs_trans *t)
+{
+	if (t->eng)
+		pohmelfs_crypto_thread_make_ready(t->eng->thread);
+	kfree(t);
+}
+
+struct netfs_trans *netfs_trans_alloc(struct pohmelfs_sb *psb, unsigned int size,
+		unsigned int flags, unsigned int nr)
+{
+	struct netfs_trans *t;
+	unsigned int num, cont, pad, size_no_trans;
+	unsigned int crypto_added = 0;
+	struct netfs_cmd *cmd;
+
+	if (psb->perform_crypto)
+		crypto_added = psb->crypto_attached_size;
+
+	/*
+	 * |sizeof(struct netfs_trans)|
+	 * |sizeof(struct netfs_cmd)| - transaction header
+	 * |size| - buffer with requested size
+	 * |padding| - crypto padding, zero bytes
+	 * |nr * sizeof(struct page *)| - array of page pointers
+	 *
+	 * Overall size should be less than PAGE_SIZE for guaranteed allocation.
+	 */
+
+	cont = size;
+	size = ALIGN(size, psb->crypto_align_size);
+	pad = size - cont;
+
+	size_no_trans = size + sizeof(struct netfs_cmd) * 2 + crypto_added;
+
+	cont = sizeof(struct netfs_trans) + size_no_trans;
+
+	num = (PAGE_SIZE - cont)/sizeof(struct page *);
+
+	if (nr > num)
+		nr = num;
+
+	t = kzalloc(cont + nr*sizeof(struct page *), GFP_NOIO);
+	if (!t)
+		goto err_out_exit;
+
+	t->iovec.iov_base = (void *)(t + 1);
+	t->pages = (struct page **)(t->iovec.iov_base + size_no_trans);
+
+	/*
+	 * Reserving space for transaction header.
+	 */
+	t->iovec.iov_len = sizeof(struct netfs_cmd) + crypto_added;
+
+	netfs_trans_init_static(t, nr, size_no_trans);
+
+	t->flags = flags;
+	t->psb = psb;
+
+	cmd = (struct netfs_cmd *)t->iovec.iov_base;
+
+	cmd->size = size;
+	cmd->cpad = pad;
+	cmd->csize = crypto_added;
+
+	dprintk("%s: t: %p, gen: %u, size: %u, padding: %u, align_size: %u, flags: %x, "
+			"page_num: %u, base: %p, pages: %p.\n",
+			__func__, t, t->gen, size, pad, psb->crypto_align_size, flags, nr,
+			t->iovec.iov_base, t->pages);
+
+	return t;
+
+err_out_exit:
+	return NULL;
+}
+
+int netfs_trans_init(void)
+{
+	int err = -ENOMEM;
+
+	netfs_trans_dst = kmem_cache_create("netfs_trans_dst", sizeof(struct netfs_trans_dst),
+			0, 0, NULL);
+	if (!netfs_trans_dst)
+		goto err_out_exit;
+
+	netfs_trans_dst_pool = mempool_create_slab_pool(256, netfs_trans_dst);
+	if (!netfs_trans_dst_pool)
+		goto err_out_free;
+
+	return 0;
+
+err_out_free:
+	kmem_cache_destroy(netfs_trans_dst);
+err_out_exit:
+	return err;
+}
+
+void netfs_trans_exit(void)
+{
+	mempool_destroy(netfs_trans_dst_pool);
+	kmem_cache_destroy(netfs_trans_dst);
+}
