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  1. /*
  2.  * Copyright (c) 2008 Jakub Jermar
  3.  * Copyright (c) 2008 Martin Decky
  4.  * All rights reserved.
  5.  *
  6.  * Redistribution and use in source and binary forms, with or without
  7.  * modification, are permitted provided that the following conditions
  8.  * are met:
  9.  *
  10.  * - Redistributions of source code must retain the above copyright
  11.  *   notice, this list of conditions and the following disclaimer.
  12.  * - Redistributions in binary form must reproduce the above copyright
  13.  *   notice, this list of conditions and the following disclaimer in the
  14.  *   documentation and/or other materials provided with the distribution.
  15.  * - The name of the author may not be used to endorse or promote products
  16.  *   derived from this software without specific prior written permission.
  17.  *
  18.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28.  */
  29.  
  30. /** @addtogroup libblock
  31.  * @{
  32.  */
  33. /**
  34.  * @file
  35.  */
  36.  
  37. #ifndef LIBBLOCK_LIBBLOCK_H_
  38. #define LIBBLOCK_LIBBLOCK_H_
  39.  
  40. #include <stdint.h>
  41. #include "../../srv/vfs/vfs.h"
  42. #include <futex.h>
  43. #include <rwlock.h>
  44. #include <libadt/hash_table.h>
  45. #include <libadt/list.h>
  46.  
  47. /*
  48.  * Flags that can be used with block_get().
  49.  */
  50.  
  51. /**
  52.  * This macro is a symbolic value for situations where no special flags are
  53.  * needed.
  54.  */
  55. #define BLOCK_FLAGS_NONE    0
  56.  
  57. /**
  58.  * When the client of block_get() intends to overwrite the current contents of
  59.  * the block, this flag is used to avoid the unnecessary read.
  60.  */
  61. #define BLOCK_FLAGS_NOREAD  1
  62.  
  63. typedef unsigned bn_t;  /**< Block number type. */
  64.  
  65. typedef struct block {
  66.     /** Futex protecting the reference count. */
  67.     futex_t lock;
  68.     /** Number of references to the block_t structure. */
  69.     unsigned refcnt;
  70.     /** If true, the block needs to be written back to the block device. */
  71.     bool dirty;
  72.     /** Readers / Writer lock protecting the contents of the block. */
  73.     rwlock_t contents_lock;
  74.     /** Handle of the device where the block resides. */
  75.     dev_handle_t dev_handle;
  76.     /** Block offset on the block device. Counted in 'size'-byte blocks. */
  77.     bn_t boff;
  78.     /** Size of the block. */
  79.     size_t size;
  80.     /** Link for placing the block into the free block list. */
  81.     link_t free_link;
  82.     /** Link for placing the block into the block hash table. */
  83.     link_t hash_link;
  84.     /** Buffer with the block data. */
  85.     void *data;
  86. } block_t;
  87.  
  88. extern int block_init(dev_handle_t, size_t);
  89. extern void block_fini(dev_handle_t);
  90.  
  91. extern int block_bb_read(dev_handle_t, off_t, size_t);
  92. extern void *block_bb_get(dev_handle_t);
  93.  
  94. extern int block_cache_init(dev_handle_t, size_t, unsigned);
  95.  
  96. extern block_t *block_get(dev_handle_t, bn_t, int flags);
  97. extern void block_put(block_t *);
  98.  
  99. extern int block_read(dev_handle_t, off_t *, size_t *, off_t *, void *, size_t,
  100.     size_t);
  101.  
  102. #endif
  103.  
  104. /** @}
  105.  */
  106.  
  107.