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3521 jermar 1
/*
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 * Copyright (c) 2008 Jakub Jermar
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 * Copyright (c) 2008 Martin Decky
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup libblock
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 * @{
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 */
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/**
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 * @file
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 */
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#ifndef LIBBLOCK_LIBBLOCK_H_
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#define LIBBLOCK_LIBBLOCK_H_ 
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#include <stdint.h>
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#include "../../srv/vfs/vfs.h"
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#include <futex.h>
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#include <rwlock.h>
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#include <libadt/hash_table.h>
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#include <libadt/list.h>
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/*
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 * Flags that can be used with block_get().
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 */
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/**
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 * This macro is a symbolic value for situations where no special flags are
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 * needed.
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 */
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#define BLOCK_FLAGS_NONE    0
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/**
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 * When the client of block_get() intends to overwrite the current contents of
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 * the block, this flag is used to avoid the unnecessary read.
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 */
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#define BLOCK_FLAGS_NOREAD  1
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typedef unsigned bn_t;  /**< Block number type. */
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typedef struct block {
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    /** Futex protecting the reference count. */
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    futex_t lock;
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    /** Number of references to the block_t structure. */
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    unsigned refcnt;
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    /** If true, the block needs to be written back to the block device. */
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    bool dirty;
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    /** Readers / Writer lock protecting the contents of the block. */
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    rwlock_t contents_lock;
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    /** Handle of the device where the block resides. */
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    dev_handle_t dev_handle;
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    /** Block offset on the block device. Counted in 'size'-byte blocks. */
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    bn_t boff;
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    /** Size of the block. */
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    size_t size;
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    /** Link for placing the block into the free block list. */
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    link_t free_link;
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    /** Link for placing the block into the block hash table. */
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    link_t hash_link;
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    /** Buffer with the block data. */
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    void *data;
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} block_t;
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extern int block_init(dev_handle_t, size_t);
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extern void block_fini(dev_handle_t);
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extern int block_bb_read(dev_handle_t, off_t, size_t);
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extern void *block_bb_get(dev_handle_t);
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extern int block_cache_init(dev_handle_t, size_t, unsigned);
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extern block_t *block_get(dev_handle_t, bn_t, int flags);
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extern void block_put(block_t *);
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extern int block_read(int, off_t *, size_t *, off_t *, void *, size_t, size_t);
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#endif
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/** @}
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 */
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