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/*

 * Copyright (c) 2008 Jakub Jermar

 * Copyright (c) 2008 Martin Decky

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/** @addtogroup libblock

 * @{

 */

/**

 * @file

 * @brief

 */

#include "libblock.h"

#include "../../srv/vfs/vfs.h"

#include <ipc/devmap.h>

#include <ipc/bd.h>

#include <ipc/services.h>

#include <errno.h>

#include <sys/mman.h>

#include <async.h>

#include <ipc/ipc.h>

#include <as.h>

#include <assert.h>

#include <futex.h>

#include <libadt/list.h>

#include <libadt/hash_table.h>

/** Lock protecting the device connection list */

static futex_t dcl_lock = FUTEX_INITIALIZER;

/** Device connection list head. */

static LIST_INITIALIZE(dcl_head);

#define CACHE_BUCKETS_LOG2      10

#define CACHE_BUCKETS           (1 << CACHE_BUCKETS_LOG2)

typedef struct {

    futex_t lock;

    size_t block_size;      /**< Block size. */

    unsigned block_count;       /**< Total number of blocks. */

    hash_table_t block_hash;

    link_t free_head;

} cache_t;

typedef struct {

    link_t link;

    int dev_handle;

    int dev_phone;

    void *com_area;

    size_t com_size;

    void *bb_buf;

    off_t bb_off;

    size_t bb_size;

    cache_t *cache;

} devcon_t;

static devcon_t *devcon_search(dev_handle_t dev_handle)

{

    link_t *cur;

    futex_down(&dcl_lock);

    for (cur = dcl_head.next; cur != &dcl_head; cur = cur->next) {

        devcon_t *devcon = list_get_instance(cur, devcon_t, link);

        if (devcon->dev_handle == dev_handle) {

            futex_up(&dcl_lock);

            return devcon;

        }

    }

    futex_up(&dcl_lock);

    return NULL;

}

static int devcon_add(dev_handle_t dev_handle, int dev_phone, void *com_area,

   size_t com_size)

{

    link_t *cur;

    devcon_t *devcon;

    devcon = malloc(sizeof(devcon_t));

    if (!devcon)

        return ENOMEM;

    link_initialize(&devcon->link);

    devcon->dev_handle = dev_handle;

    devcon->dev_phone = dev_phone;

    devcon->com_area = com_area;

    devcon->com_size = com_size;

    devcon->bb_buf = NULL;

    devcon->bb_off = 0;

    devcon->bb_size = 0;

    devcon->cache = NULL;

    futex_down(&dcl_lock);

    for (cur = dcl_head.next; cur != &dcl_head; cur = cur->next) {

        devcon_t *d = list_get_instance(cur, devcon_t, link);

        if (d->dev_handle == dev_handle) {

            futex_up(&dcl_lock);

            free(devcon);

            return EEXIST;

        }

    }

    list_append(&devcon->link, &dcl_head);

    futex_up(&dcl_lock);

    return EOK;

}

static void devcon_remove(devcon_t *devcon)

{

    futex_down(&dcl_lock);

    list_remove(&devcon->link);

    futex_up(&dcl_lock);

}

int block_init(dev_handle_t dev_handle, size_t com_size)

{

    int rc;

    int dev_phone;

    void *com_area;

    com_area = mmap(NULL, com_size, PROTO_READ | PROTO_WRITE,

        MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);

    if (!com_area) {

        return ENOMEM;

    }

    dev_phone = devmap_device_connect(dev_handle, IPC_FLAG_BLOCKING);

    if (dev_phone < 0) {

        munmap(com_area, com_size);

        return dev_phone;

    }

    rc = ipc_share_out_start(dev_phone, com_area,

        AS_AREA_READ | AS_AREA_WRITE);

    if (rc != EOK) {

            munmap(com_area, com_size);

        ipc_hangup(dev_phone);

        return rc;

    }

    rc = devcon_add(dev_handle, dev_phone, com_area, com_size);

    if (rc != EOK) {

        munmap(com_area, com_size);

        ipc_hangup(dev_phone);

        return rc;

    }

    return EOK;

}

void block_fini(dev_handle_t dev_handle)

{

    devcon_t *devcon = devcon_search(dev_handle);

    assert(devcon);

    devcon_remove(devcon);

    if (devcon->bb_buf)

        free(devcon->bb_buf);

    if (devcon->cache) {

        hash_table_destroy(&devcon->cache->block_hash);

        free(devcon->cache);

    }

    munmap(devcon->com_area, devcon->com_size);

    ipc_hangup(devcon->dev_phone);

    free(devcon);  

}

int block_bb_read(dev_handle_t dev_handle, off_t off, size_t size)

{

    void *bb_buf;

    int rc;

    devcon_t *devcon = devcon_search(dev_handle);

    if (!devcon)

        return ENOENT;

    if (devcon->bb_buf)

        return EEXIST;

    bb_buf = malloc(size);

    if (!bb_buf)

        return ENOMEM;

    off_t bufpos = 0;

    size_t buflen = 0;

    rc = block_read(dev_handle, &bufpos, &buflen, &off,

        bb_buf, size, size);

    if (rc != EOK) {

            free(bb_buf);

        return rc;

    }

    devcon->bb_buf = bb_buf;

    devcon->bb_off = off;

    devcon->bb_size = size;

    return EOK;

}

void *block_bb_get(dev_handle_t dev_handle)

{

    devcon_t *devcon = devcon_search(dev_handle);

    assert(devcon);

    return devcon->bb_buf;

}

static hash_index_t cache_hash(unsigned long *key)

{

    return *key & (CACHE_BUCKETS - 1);

}

static int cache_compare(unsigned long *key, hash_count_t keys, link_t *item)

{

    block_t *b = hash_table_get_instance(item, block_t, hash_link);

    return b->boff == *key;

}

static void cache_remove_callback(link_t *item)

{

}

static hash_table_operations_t cache_ops = {

    .hash = cache_hash,

    .compare = cache_compare,

    .remove_callback = cache_remove_callback

};

int block_cache_init(dev_handle_t dev_handle, size_t size, unsigned blocks)

{

    devcon_t *devcon = devcon_search(dev_handle);

    cache_t *cache;

    if (!devcon)

        return ENOENT;

    if (devcon->cache)

        return EEXIST;

    cache = malloc(sizeof(cache_t));

    if (!cache)

        return ENOMEM;

    futex_initialize(&cache->lock, 1);

    list_initialize(&cache->free_head);

    cache->block_size = size;

    cache->block_count = blocks;

    if (!hash_table_create(&cache->block_hash, CACHE_BUCKETS, 1,

        &cache_ops)) {

        free(cache);

        return ENOMEM;

    }

    devcon->cache = cache;

    return EOK;

}

static bool cache_can_grow(cache_t *cache)

{

    return true;

}

static void block_initialize(block_t *b)

{

    futex_initialize(&b->lock, 1);

    b->refcnt = 1;

    b->dirty = false;

    rwlock_initialize(&b->contents_lock);

    link_initialize(&b->free_link);

    link_initialize(&b->hash_link);

}

/** Instantiate a block in memory and get a reference to it.

 *

 * @param dev_handle        Device handle of the block device.

 * @param boff          Block offset.

 * @param flags         If BLOCK_FLAGS_NOREAD is specified, block_get()

 *              will not read the contents of the block from the

 *              device.

 *

 * @return          Block structure.

 */

block_t *block_get(dev_handle_t dev_handle, bn_t boff, int flags)

{

    devcon_t *devcon;

    cache_t *cache;

    block_t *b;

    link_t *l;

    unsigned long key = boff;

    devcon = devcon_search(dev_handle);

    assert(devcon);

    assert(devcon->cache);

    cache = devcon->cache;

    futex_down(&cache->lock);

    l = hash_table_find(&cache->block_hash, &key);

    if (l) {

        /*

         * We found the block in the cache.

         */

        b = hash_table_get_instance(l, block_t, hash_link);

        futex_down(&b->lock);

        if (b->refcnt++ == 0)

            list_remove(&b->free_link);

        futex_up(&b->lock);

        futex_up(&cache->lock);

    } else {

        /*

         * The block was not found in the cache.

         */

        int rc;

        off_t bufpos = 0;

        size_t buflen = 0;

        off_t pos = boff * cache->block_size;

        bool sync = false;

        if (cache_can_grow(cache)) {

            /*

             * We can grow the cache by allocating new blocks.

             * Should the allocation fail, we fail over and try to

             * recycle a block from the cache.

             */

            b = malloc(sizeof(block_t));

            if (!b)

                goto recycle;

            b->data = malloc(cache->block_size);

            if (!b->data) {

                free(b);

                goto recycle;

            }

        } else {

            /*

             * Try to recycle a block from the free list.

             */

            unsigned long temp_key;

recycle:

            assert(!list_empty(&cache->free_head));

            l = cache->free_head.next;

            list_remove(l);

            b = hash_table_get_instance(l, block_t, hash_link);

            sync = b->dirty;

            temp_key = b->boff;

            hash_table_remove(&cache->block_hash, &temp_key, 1);

        }

        block_initialize(b);

        b->dev_handle = dev_handle;

        b->size = cache->block_size;

        b->boff = boff;

        hash_table_insert(&cache->block_hash, &key, &b->hash_link);

        /*

         * Lock the block before releasing the cache lock. Thus we don't

         * kill concurent operations on the cache while doing I/O on the

         * block.

         */

        futex_down(&b->lock);

        futex_up(&cache->lock);

        if (sync) {

            /*

             * The block is dirty and needs to be written back to

             * the device before we can read in the new contents.

             */

            abort();    /* TODO: block_write() */

        }

        if (!(flags & BLOCK_FLAGS_NOREAD)) {

            /*

             * The block contains old or no data. We need to read

             * the new contents from the device.

             */

            rc = block_read(dev_handle, &bufpos, &buflen, &pos,

                b->data, cache->block_size, cache->block_size);

            assert(rc == EOK);

        }

        futex_up(&b->lock);

    }

    return b;

}

/** Release a reference to a block.

 *

 * If the last reference is dropped, the block is put on the free list.

 *

 * @param block     Block of which a reference is to be released.

 */

void block_put(block_t *block)

{

    devcon_t *devcon = devcon_search(block->dev_handle);

    cache_t *cache;

    assert(devcon);

    assert(devcon->cache);

    cache = devcon->cache;

    futex_down(&cache->lock);

    futex_down(&block->lock);

    if (!--block->refcnt) {

        /*

         * Last reference to the block was dropped, put the block on the

         * free list.

         */

        list_append(&block->free_link, &cache->free_head);

    }

    futex_up(&block->lock);

    futex_up(&cache->lock);

}

/** Read data from a block device.

 *

 * @param dev_handle    Device handle of the block device.

 * @param bufpos    Pointer to the first unread valid offset within the

 *          communication buffer.

 * @param buflen    Pointer to the number of unread bytes that are ready in

 *          the communication buffer.

 * @param pos       Device position to be read.

 * @param dst       Destination buffer.

 * @param size      Size of the destination buffer.

 * @param block_size    Block size to be used for the transfer.

 *

 * @return      EOK on success or a negative return code on failure.

 */

int

block_read(int dev_handle, off_t *bufpos, size_t *buflen, off_t *pos, void *dst,

    size_t size, size_t block_size)

{

    off_t offset = 0;

    size_t left = size;

    devcon_t *devcon = devcon_search(dev_handle);

    assert(devcon);

    while (left > 0) {

        size_t rd;

        if (*bufpos + left < *buflen)

            rd = left;

        else

            rd = *buflen - *bufpos;

        if (rd > 0) {

            /*

             * Copy the contents of the communication buffer to the

             * destination buffer.

             */

            memcpy(dst + offset, devcon->com_area + *bufpos, rd);

            offset += rd;

            *bufpos += rd;

            *pos += rd;

            left -= rd;

        }

        if (*bufpos == *buflen) {

            /* Refill the communication buffer with a new block. */

            ipcarg_t retval;

            int rc = async_req_2_1(devcon->dev_phone, BD_READ_BLOCK,

                *pos / block_size, block_size, &retval);

            if ((rc != EOK) || (retval != EOK))

                return (rc != EOK ? rc : retval);

            *bufpos = 0;

            *buflen = block_size;

        }

    }

    return EOK;

}

/** @}

 */