Merge commit 'v2.6.35' into kbuild/kconfig

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / staging / pohmelfs / crypto.c

/*
 * 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/crypto.h>
#include <linux/highmem.h>
#include <linux/kthread.h>
#include <linux/pagemap.h>
#include <linux/slab.h>

#include "netfs.h"

static struct crypto_hash *pohmelfs_init_hash(struct pohmelfs_sb *psb)
{
        int err;
        struct crypto_hash *hash;

        hash = crypto_alloc_hash(psb->hash_string, 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(hash)) {
                err = PTR_ERR(hash);
                dprintk("%s: idx: %u: failed to allocate hash '%s', err: %d.\n",
                                __func__, psb->idx, psb->hash_string, err);
                goto err_out_exit;
        }

        psb->crypto_attached_size = crypto_hash_digestsize(hash);

        if (!psb->hash_keysize)
                return hash;

        err = crypto_hash_setkey(hash, psb->hash_key, psb->hash_keysize);
        if (err) {
                dprintk("%s: idx: %u: failed to set key for hash '%s', err: %d.\n",
                                __func__, psb->idx, psb->hash_string, err);
                goto err_out_free;
        }

        return hash;

err_out_free:
        crypto_free_hash(hash);
err_out_exit:
        return ERR_PTR(err);
}

static struct crypto_ablkcipher *pohmelfs_init_cipher(struct pohmelfs_sb *psb)
{
        int err = -EINVAL;
        struct crypto_ablkcipher *cipher;

        if (!psb->cipher_keysize)
                goto err_out_exit;

        cipher = crypto_alloc_ablkcipher(psb->cipher_string, 0, 0);
        if (IS_ERR(cipher)) {
                err = PTR_ERR(cipher);
                dprintk("%s: idx: %u: failed to allocate cipher '%s', err: %d.\n",
                                __func__, psb->idx, psb->cipher_string, err);
                goto err_out_exit;
        }

        crypto_ablkcipher_clear_flags(cipher, ~0);

        err = crypto_ablkcipher_setkey(cipher, psb->cipher_key, psb->cipher_keysize);
        if (err) {
                dprintk("%s: idx: %u: failed to set key for cipher '%s', err: %d.\n",
                                __func__, psb->idx, psb->cipher_string, err);
                goto err_out_free;
        }

        return cipher;

err_out_free:
        crypto_free_ablkcipher(cipher);
err_out_exit:
        return ERR_PTR(err);
}

int pohmelfs_crypto_engine_init(struct pohmelfs_crypto_engine *e, struct pohmelfs_sb *psb)
{
        int err;

        e->page_num = 0;

        e->size = PAGE_SIZE;
        e->data = kmalloc(e->size, GFP_KERNEL);
        if (!e->data) {
                err = -ENOMEM;
                goto err_out_exit;
        }

        if (psb->hash_string) {
                e->hash = pohmelfs_init_hash(psb);
                if (IS_ERR(e->hash)) {
                        err = PTR_ERR(e->hash);
                        e->hash = NULL;
                        goto err_out_free;
                }
        }

        if (psb->cipher_string) {
                e->cipher = pohmelfs_init_cipher(psb);
                if (IS_ERR(e->cipher)) {
                        err = PTR_ERR(e->cipher);
                        e->cipher = NULL;
                        goto err_out_free_hash;
                }
        }

        return 0;

err_out_free_hash:
        crypto_free_hash(e->hash);
err_out_free:
        kfree(e->data);
err_out_exit:
        return err;
}

void pohmelfs_crypto_engine_exit(struct pohmelfs_crypto_engine *e)
{
        if (e->hash)
                crypto_free_hash(e->hash);
        if (e->cipher)
                crypto_free_ablkcipher(e->cipher);
        kfree(e->data);
}

static void pohmelfs_crypto_complete(struct crypto_async_request *req, int err)
{
        struct pohmelfs_crypto_completion *c = req->data;

        if (err == -EINPROGRESS)
                return;

        dprintk("%s: req: %p, err: %d.\n", __func__, req, err);
        c->error = err;
        complete(&c->complete);
}

static int pohmelfs_crypto_process(struct ablkcipher_request *req,
                struct scatterlist *sg_dst, struct scatterlist *sg_src,
                void *iv, int enc, unsigned long timeout)
{
        struct pohmelfs_crypto_completion complete;
        int err;

        init_completion(&complete.complete);
        complete.error = -EINPROGRESS;

        ablkcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
                                        pohmelfs_crypto_complete, &complete);

        ablkcipher_request_set_crypt(req, sg_src, sg_dst, sg_src->length, iv);

        if (enc)
                err = crypto_ablkcipher_encrypt(req);
        else
                err = crypto_ablkcipher_decrypt(req);

        switch (err) {
        case -EINPROGRESS:
        case -EBUSY:
                err = wait_for_completion_interruptible_timeout(&complete.complete,
                                        timeout);
                if (!err)
                        err = -ETIMEDOUT;
                else if (err > 0)
                        err = complete.error;
                break;
        default:
                break;
        }

        return err;
}

int pohmelfs_crypto_process_input_data(struct pohmelfs_crypto_engine *e, u64 cmd_iv,
                void *data, struct page *page, unsigned int size)
{
        int err;
        struct scatterlist sg;

        if (!e->cipher && !e->hash)
                return 0;

        dprintk("%s: eng: %p, iv: %llx, data: %p, page: %p/%lu, size: %u.\n",
                __func__, e, cmd_iv, data, page, (page) ? page->index : 0, size);

        if (data) {
                sg_init_one(&sg, data, size);
        } else {
                sg_init_table(&sg, 1);
                sg_set_page(&sg, page, size, 0);
        }

        if (e->cipher) {
                struct ablkcipher_request *req = e->data + crypto_hash_digestsize(e->hash);
                u8 iv[32];

                memset(iv, 0, sizeof(iv));
                memcpy(iv, &cmd_iv, sizeof(cmd_iv));

                ablkcipher_request_set_tfm(req, e->cipher);

                err = pohmelfs_crypto_process(req, &sg, &sg, iv, 0, e->timeout);
                if (err)
                        goto err_out_exit;
        }

        if (e->hash) {
                struct hash_desc desc;
                void *dst = e->data + e->size/2;

                desc.tfm = e->hash;
                desc.flags = 0;

                err = crypto_hash_init(&desc);
                if (err)
                        goto err_out_exit;

                err = crypto_hash_update(&desc, &sg, size);
                if (err)
                        goto err_out_exit;

                err = crypto_hash_final(&desc, dst);
                if (err)
                        goto err_out_exit;

                err = !!memcmp(dst, e->data, crypto_hash_digestsize(e->hash));

                if (err) {
#ifdef CONFIG_POHMELFS_DEBUG
                        unsigned int i;
                        unsigned char *recv = e->data, *calc = dst;

                        dprintk("%s: eng: %p, hash: %p, cipher: %p: iv : %llx, hash mismatch (recv/calc): ",
                                        __func__, e, e->hash, e->cipher, cmd_iv);
                        for (i = 0; i < crypto_hash_digestsize(e->hash); ++i) {
#if 0
                                dprintka("%02x ", recv[i]);
                                if (recv[i] != calc[i]) {
                                        dprintka("| calc byte: %02x.\n", calc[i]);
                                        break;
                                }
#else
                                dprintka("%02x/%02x ", recv[i], calc[i]);
#endif
                        }
                        dprintk("\n");
#endif
                        goto err_out_exit;
                } else {
                        dprintk("%s: eng: %p, hash: %p, cipher: %p: hashes matched.\n",
                                        __func__, e, e->hash, e->cipher);
                }
        }

        dprintk("%s: eng: %p, size: %u, hash: %p, cipher: %p: completed.\n",
                        __func__, e, e->size, e->hash, e->cipher);

        return 0;

err_out_exit:
        dprintk("%s: eng: %p, hash: %p, cipher: %p: err: %d.\n",
                        __func__, e, e->hash, e->cipher, err);
        return err;
}

static int pohmelfs_trans_iter(struct netfs_trans *t, struct pohmelfs_crypto_engine *e,
                int (*iterator) (struct pohmelfs_crypto_engine *e,
                                  struct scatterlist *dst,
                                  struct scatterlist *src))
{
        void *data = t->iovec.iov_base + sizeof(struct netfs_cmd) + t->psb->crypto_attached_size;
        unsigned int size = t->iovec.iov_len - sizeof(struct netfs_cmd) - t->psb->crypto_attached_size;
        struct netfs_cmd *cmd = data;
        unsigned int sz, pages = t->attached_pages, i, csize, cmd_cmd, dpage_idx;
        struct scatterlist sg_src, sg_dst;
        int err;

        while (size) {
                cmd = data;
                cmd_cmd = __be16_to_cpu(cmd->cmd);
                csize = __be32_to_cpu(cmd->size);
                cmd->iv = __cpu_to_be64(e->iv);

                if (cmd_cmd == NETFS_READ_PAGES || cmd_cmd == NETFS_READ_PAGE)
                        csize = __be16_to_cpu(cmd->ext);

                sz = csize + __be16_to_cpu(cmd->cpad) + sizeof(struct netfs_cmd);

                dprintk("%s: size: %u, sz: %u, cmd_size: %u, cmd_cpad: %u.\n",
                                __func__, size, sz, __be32_to_cpu(cmd->size), __be16_to_cpu(cmd->cpad));

                data += sz;
                size -= sz;

                sg_init_one(&sg_src, cmd->data, sz - sizeof(struct netfs_cmd));
                sg_init_one(&sg_dst, cmd->data, sz - sizeof(struct netfs_cmd));

                err = iterator(e, &sg_dst, &sg_src);
                if (err)
                        return err;
        }

        if (!pages)
                return 0;

        dpage_idx = 0;
        for (i = 0; i < t->page_num; ++i) {
                struct page *page = t->pages[i];
                struct page *dpage = e->pages[dpage_idx];

                if (!page)
                        continue;

                sg_init_table(&sg_src, 1);
                sg_init_table(&sg_dst, 1);
                sg_set_page(&sg_src, page, page_private(page), 0);
                sg_set_page(&sg_dst, dpage, page_private(page), 0);

                err = iterator(e, &sg_dst, &sg_src);
                if (err)
                        return err;

                pages--;
                if (!pages)
                        break;
                dpage_idx++;
        }

        return 0;
}

static int pohmelfs_encrypt_iterator(struct pohmelfs_crypto_engine *e,
                struct scatterlist *sg_dst, struct scatterlist *sg_src)
{
        struct ablkcipher_request *req = e->data;
        u8 iv[32];

        memset(iv, 0, sizeof(iv));

        memcpy(iv, &e->iv, sizeof(e->iv));

        return pohmelfs_crypto_process(req, sg_dst, sg_src, iv, 1, e->timeout);
}

static int pohmelfs_encrypt(struct pohmelfs_crypto_thread *tc)
{
        struct netfs_trans *t = tc->trans;
        struct pohmelfs_crypto_engine *e = &tc->eng;
        struct ablkcipher_request *req = e->data;

        memset(req, 0, sizeof(struct ablkcipher_request));
        ablkcipher_request_set_tfm(req, e->cipher);

        e->iv = pohmelfs_gen_iv(t);

        return pohmelfs_trans_iter(t, e, pohmelfs_encrypt_iterator);
}

static int pohmelfs_hash_iterator(struct pohmelfs_crypto_engine *e,
                struct scatterlist *sg_dst, struct scatterlist *sg_src)
{
        return crypto_hash_update(e->data, sg_src, sg_src->length);
}

static int pohmelfs_hash(struct pohmelfs_crypto_thread *tc)
{
        struct pohmelfs_crypto_engine *e = &tc->eng;
        struct hash_desc *desc = e->data;
        unsigned char *dst = tc->trans->iovec.iov_base + sizeof(struct netfs_cmd);
        int err;

        desc->tfm = e->hash;
        desc->flags = 0;

        err = crypto_hash_init(desc);
        if (err)
                return err;

        err = pohmelfs_trans_iter(tc->trans, e, pohmelfs_hash_iterator);
        if (err)
                return err;

        err = crypto_hash_final(desc, dst);
        if (err)
                return err;

        {
                unsigned int i;
                dprintk("%s: ", __func__);
                for (i = 0; i < tc->psb->crypto_attached_size; ++i)
                        dprintka("%02x ", dst[i]);
                dprintka("\n");
        }

        return 0;
}

static void pohmelfs_crypto_pages_free(struct pohmelfs_crypto_engine *e)
{
        unsigned int i;

        for (i = 0; i < e->page_num; ++i)
                __free_page(e->pages[i]);
        kfree(e->pages);
}

static int pohmelfs_crypto_pages_alloc(struct pohmelfs_crypto_engine *e, struct pohmelfs_sb *psb)
{
        unsigned int i;

        e->pages = kmalloc(psb->trans_max_pages * sizeof(struct page *), GFP_KERNEL);
        if (!e->pages)
                return -ENOMEM;

        for (i = 0; i < psb->trans_max_pages; ++i) {
                e->pages[i] = alloc_page(GFP_KERNEL);
                if (!e->pages[i])
                        break;
        }

        e->page_num = i;
        if (!e->page_num)
                goto err_out_free;

        return 0;

err_out_free:
        kfree(e->pages);
        return -ENOMEM;
}

static void pohmelfs_sys_crypto_exit_one(struct pohmelfs_crypto_thread *t)
{
        struct pohmelfs_sb *psb = t->psb;

        if (t->thread)
                kthread_stop(t->thread);

        mutex_lock(&psb->crypto_thread_lock);
        list_del(&t->thread_entry);
        psb->crypto_thread_num--;
        mutex_unlock(&psb->crypto_thread_lock);

        pohmelfs_crypto_engine_exit(&t->eng);
        pohmelfs_crypto_pages_free(&t->eng);
        kfree(t);
}

static int pohmelfs_crypto_finish(struct netfs_trans *t, struct pohmelfs_sb *psb, int err)
{
        struct netfs_cmd *cmd = t->iovec.iov_base;
        netfs_convert_cmd(cmd);

        if (likely(!err))
                err = netfs_trans_finish_send(t, psb);

        t->result = err;
        netfs_trans_put(t);

        return err;
}

void pohmelfs_crypto_thread_make_ready(struct pohmelfs_crypto_thread *th)
{
        struct pohmelfs_sb *psb = th->psb;

        th->page = NULL;
        th->trans = NULL;

        mutex_lock(&psb->crypto_thread_lock);
        list_move_tail(&th->thread_entry, &psb->crypto_ready_list);
        mutex_unlock(&psb->crypto_thread_lock);
        wake_up(&psb->wait);
}

static int pohmelfs_crypto_thread_trans(struct pohmelfs_crypto_thread *t)
{
        struct netfs_trans *trans;
        int err = 0;

        trans = t->trans;
        trans->eng = NULL;

        if (t->eng.hash) {
                err = pohmelfs_hash(t);
                if (err)
                        goto out_complete;
        }

        if (t->eng.cipher) {
                err = pohmelfs_encrypt(t);
                if (err)
                        goto out_complete;
                trans->eng = &t->eng;
        }

out_complete:
        t->page = NULL;
        t->trans = NULL;

        if (!trans->eng)
                pohmelfs_crypto_thread_make_ready(t);

        pohmelfs_crypto_finish(trans, t->psb, err);
        return err;
}

static int pohmelfs_crypto_thread_page(struct pohmelfs_crypto_thread *t)
{
        struct pohmelfs_crypto_engine *e = &t->eng;
        struct page *page = t->page;
        int err;

        WARN_ON(!PageChecked(page));

        err = pohmelfs_crypto_process_input_data(e, e->iv, NULL, page, t->size);
        if (!err)
                SetPageUptodate(page);
        else
                SetPageError(page);
        unlock_page(page);
        page_cache_release(page);

        pohmelfs_crypto_thread_make_ready(t);

        return err;
}

static int pohmelfs_crypto_thread_func(void *data)
{
        struct pohmelfs_crypto_thread *t = data;

        while (!kthread_should_stop()) {
                wait_event_interruptible(t->wait, kthread_should_stop() ||
                                t->trans || t->page);

                if (kthread_should_stop())
                        break;

                if (!t->trans && !t->page)
                        continue;

                dprintk("%s: thread: %p, trans: %p, page: %p.\n",
                                __func__, t, t->trans, t->page);

                if (t->trans)
                        pohmelfs_crypto_thread_trans(t);
                else if (t->page)
                        pohmelfs_crypto_thread_page(t);
        }

        return 0;
}

static void pohmelfs_crypto_flush(struct pohmelfs_sb *psb, struct list_head *head)
{
        while (!list_empty(head)) {
                struct pohmelfs_crypto_thread *t = NULL;

                mutex_lock(&psb->crypto_thread_lock);
                if (!list_empty(head)) {
                        t = list_first_entry(head, struct pohmelfs_crypto_thread, thread_entry);
                        list_del_init(&t->thread_entry);
                }
                mutex_unlock(&psb->crypto_thread_lock);

                if (t)
                        pohmelfs_sys_crypto_exit_one(t);
        }
}

static void pohmelfs_sys_crypto_exit(struct pohmelfs_sb *psb)
{
        while (!list_empty(&psb->crypto_active_list) || !list_empty(&psb->crypto_ready_list)) {
                dprintk("%s: crypto_thread_num: %u.\n", __func__, psb->crypto_thread_num);
                pohmelfs_crypto_flush(psb, &psb->crypto_active_list);
                pohmelfs_crypto_flush(psb, &psb->crypto_ready_list);
        }
}

static int pohmelfs_sys_crypto_init(struct pohmelfs_sb *psb)
{
        unsigned int i;
        struct pohmelfs_crypto_thread *t;
        struct pohmelfs_config *c;
        struct netfs_state *st;
        int err;

        list_for_each_entry(c, &psb->state_list, config_entry) {
                st = &c->state;

                err = pohmelfs_crypto_engine_init(&st->eng, psb);
                if (err)
                        goto err_out_exit;

                dprintk("%s: st: %p, eng: %p, hash: %p, cipher: %p.\n",
                                __func__, st, &st->eng, &st->eng.hash, &st->eng.cipher);
        }

        for (i = 0; i < psb->crypto_thread_num; ++i) {
                err = -ENOMEM;
                t = kzalloc(sizeof(struct pohmelfs_crypto_thread), GFP_KERNEL);
                if (!t)
                        goto err_out_free_state_engines;

                init_waitqueue_head(&t->wait);

                t->psb = psb;
                t->trans = NULL;
                t->eng.thread = t;

                err = pohmelfs_crypto_engine_init(&t->eng, psb);
                if (err)
                        goto err_out_free_state_engines;

                err = pohmelfs_crypto_pages_alloc(&t->eng, psb);
                if (err)
                        goto err_out_free;

                t->thread = kthread_run(pohmelfs_crypto_thread_func, t,
                                "pohmelfs-crypto-%d-%d", psb->idx, i);
                if (IS_ERR(t->thread)) {
                        err = PTR_ERR(t->thread);
                        t->thread = NULL;
                        goto err_out_free;
                }

                if (t->eng.cipher)
                        psb->crypto_align_size = crypto_ablkcipher_blocksize(t->eng.cipher);

                mutex_lock(&psb->crypto_thread_lock);
                list_add_tail(&t->thread_entry, &psb->crypto_ready_list);
                mutex_unlock(&psb->crypto_thread_lock);
        }

        psb->crypto_thread_num = i;
        return 0;

err_out_free:
        pohmelfs_sys_crypto_exit_one(t);
err_out_free_state_engines:
        list_for_each_entry(c, &psb->state_list, config_entry) {
                st = &c->state;
                pohmelfs_crypto_engine_exit(&st->eng);
        }
err_out_exit:
        pohmelfs_sys_crypto_exit(psb);
        return err;
}

void pohmelfs_crypto_exit(struct pohmelfs_sb *psb)
{
        pohmelfs_sys_crypto_exit(psb);

        kfree(psb->hash_string);
        kfree(psb->cipher_string);
}

static int pohmelfs_crypt_init_complete(struct page **pages, unsigned int page_num,
                void *private, int err)
{
        struct pohmelfs_sb *psb = private;

        psb->flags = -err;
        dprintk("%s: err: %d.\n", __func__, err);

        wake_up(&psb->wait);

        return err;
}

static int pohmelfs_crypto_init_handshake(struct pohmelfs_sb *psb)
{
        struct netfs_trans *t;
        struct netfs_crypto_capabilities *cap;
        struct netfs_cmd *cmd;
        char *str;
        int err = -ENOMEM, size;

        size = sizeof(struct netfs_crypto_capabilities) +
                psb->cipher_strlen + psb->hash_strlen + 2; /* 0 bytes */

        t = netfs_trans_alloc(psb, size, 0, 0);
        if (!t)
                goto err_out_exit;

        t->complete = pohmelfs_crypt_init_complete;
        t->private = psb;

        cmd = netfs_trans_current(t);
        cap = (struct netfs_crypto_capabilities *)(cmd + 1);
        str = (char *)(cap + 1);

        cmd->cmd = NETFS_CAPABILITIES;
        cmd->id = POHMELFS_CRYPTO_CAPABILITIES;
        cmd->size = size;
        cmd->start = 0;
        cmd->ext = 0;
        cmd->csize = 0;

        netfs_convert_cmd(cmd);
        netfs_trans_update(cmd, t, size);

        cap->hash_strlen = psb->hash_strlen;
        if (cap->hash_strlen) {
                sprintf(str, "%s", psb->hash_string);
                str += cap->hash_strlen;
        }

        cap->cipher_strlen = psb->cipher_strlen;
        cap->cipher_keysize = psb->cipher_keysize;
        if (cap->cipher_strlen)
                sprintf(str, "%s", psb->cipher_string);

        netfs_convert_crypto_capabilities(cap);

        psb->flags = ~0;
        err = netfs_trans_finish(t, psb);
        if (err)
                goto err_out_exit;

        err = wait_event_interruptible_timeout(psb->wait, (psb->flags != ~0),
                        psb->wait_on_page_timeout);
        if (!err)
                err = -ETIMEDOUT;
        else if (err > 0)
                err = -psb->flags;

        if (!err)
                psb->perform_crypto = 1;
        psb->flags = 0;

        /*
         * At this point NETFS_CAPABILITIES response command
         * should setup superblock in a way, which is acceptible
         * for both client and server, so if server refuses connection,
         * it will send error in transaction response.
         */

        if (err)
                goto err_out_exit;

        return 0;

err_out_exit:
        return err;
}

int pohmelfs_crypto_init(struct pohmelfs_sb *psb)
{
        int err;

        if (!psb->cipher_string && !psb->hash_string)
                return 0;

        err = pohmelfs_crypto_init_handshake(psb);
        if (err)
                return err;

        err = pohmelfs_sys_crypto_init(psb);
        if (err)
                return err;

        return 0;
}

static int pohmelfs_crypto_thread_get(struct pohmelfs_sb *psb,
                int (*action)(struct pohmelfs_crypto_thread *t, void *data), void *data)
{
        struct pohmelfs_crypto_thread *t = NULL;
        int err;

        while (!t) {
                err = wait_event_interruptible_timeout(psb->wait,
                                !list_empty(&psb->crypto_ready_list),
                                psb->wait_on_page_timeout);

                t = NULL;
                err = 0;
                mutex_lock(&psb->crypto_thread_lock);
                if (!list_empty(&psb->crypto_ready_list)) {
                        t = list_entry(psb->crypto_ready_list.prev,
                                        struct pohmelfs_crypto_thread,
                                        thread_entry);

                        list_move_tail(&t->thread_entry,
                                        &psb->crypto_active_list);

                        action(t, data);
                        wake_up(&t->wait);

                }
                mutex_unlock(&psb->crypto_thread_lock);
        }

        return err;
}

static int pohmelfs_trans_crypt_action(struct pohmelfs_crypto_thread *t, void *data)
{
        struct netfs_trans *trans = data;

        netfs_trans_get(trans);
        t->trans = trans;

        dprintk("%s: t: %p, gen: %u, thread: %p.\n", __func__, trans, trans->gen, t);
        return 0;
}

int pohmelfs_trans_crypt(struct netfs_trans *trans, struct pohmelfs_sb *psb)
{
        if ((!psb->hash_string && !psb->cipher_string) || !psb->perform_crypto) {
                netfs_trans_get(trans);
                return pohmelfs_crypto_finish(trans, psb, 0);
        }

        return pohmelfs_crypto_thread_get(psb, pohmelfs_trans_crypt_action, trans);
}

struct pohmelfs_crypto_input_action_data {
        struct page                     *page;
        struct pohmelfs_crypto_engine   *e;
        u64                             iv;
        unsigned int                    size;
};

static int pohmelfs_crypt_input_page_action(struct pohmelfs_crypto_thread *t, void *data)
{
        struct pohmelfs_crypto_input_action_data *act = data;

        memcpy(t->eng.data, act->e->data, t->psb->crypto_attached_size);

        t->size = act->size;
        t->eng.iv = act->iv;

        t->page = act->page;
        return 0;
}

int pohmelfs_crypto_process_input_page(struct pohmelfs_crypto_engine *e,
                struct page *page, unsigned int size, u64 iv)
{
        struct inode *inode = page->mapping->host;
        struct pohmelfs_crypto_input_action_data act;
        int err = -ENOENT;

        act.page = page;
        act.e = e;
        act.size = size;
        act.iv = iv;

        err = pohmelfs_crypto_thread_get(POHMELFS_SB(inode->i_sb),
                        pohmelfs_crypt_input_page_action, &act);
        if (err)
                goto err_out_exit;

        return 0;

err_out_exit:
        SetPageUptodate(page);
        page_cache_release(page);

        return err;
}