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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;

	dev_handle_t 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;

}

/** @}

 */