source: mainline/uspace/lib/libblock/libblock.h@ 3ddd90c

/*
 * 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
 */

#ifndef LIBBLOCK_LIBBLOCK_H_
#define LIBBLOCK_LIBBLOCK_H_ 

#include <stdint.h>
#include "../../srv/vfs/vfs.h"
#include <futex.h>
#include <rwlock.h>
#include <libadt/hash_table.h>
#include <libadt/list.h>

/*
 * Flags that can be used with block_get().
 */

/** 
 * This macro is a symbolic value for situations where no special flags are
 * needed.
 */
#define BLOCK_FLAGS_NONE        0

/**
 * When the client of block_get() intends to overwrite the current contents of
 * the block, this flag is used to avoid the unnecessary read.
 */
#define BLOCK_FLAGS_NOREAD      1

typedef unsigned bn_t;  /**< Block number type. */

typedef struct block {
        /** Futex protecting the reference count. */
        futex_t lock;
        /** Number of references to the block_t structure. */
        unsigned refcnt;
        /** If true, the block needs to be written back to the block device. */
        bool dirty;
        /** Readers / Writer lock protecting the contents of the block. */
        rwlock_t contents_lock;
        /** Handle of the device where the block resides. */
        dev_handle_t dev_handle;
        /** Block offset on the block device. Counted in 'size'-byte blocks. */
        bn_t boff;
        /** Size of the block. */
        size_t size;
        /** Link for placing the block into the free block list. */
        link_t free_link;
        /** Link for placing the block into the block hash table. */ 
        link_t hash_link;
        /** Buffer with the block data. */
        void *data;
} block_t;

extern int block_init(dev_handle_t, size_t);
extern void block_fini(dev_handle_t);

extern int block_bb_read(dev_handle_t, off_t, size_t);
extern void *block_bb_get(dev_handle_t);

extern int block_cache_init(dev_handle_t, size_t, unsigned);

extern block_t *block_get(dev_handle_t, bn_t, int flags);
extern void block_put(block_t *);

extern int block_read(dev_handle_t, off_t *, size_t *, off_t *, void *, size_t,
    size_t);

#endif

/** @}
 */