filters/cow/blk.h

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef NBDKIT_BLK_H
  34 #define NBDKIT_BLK_H
  35
  36 /* Initialize the overlay and bitmap. */
  37 extern int blk_init (void);
  38
  39 /* Close the overlay, free the bitmap. */
  40 extern void blk_free (void);
  41
  42 /* Allocate or resize the overlay and bitmap. */
  43 extern int blk_set_size (uint64_t new_size);
  44
  45 /* Returns the status of the block in the overlay. */
  46 extern void blk_status (uint64_t blknum, bool *present, bool *trimmed);
  47
  48 /* Read a single block from the overlay or plugin. */
  49 extern int blk_read (nbdkit_next *next,
  50                      uint64_t blknum, uint8_t *block,
  51                      bool cow_on_read, int *err)
  52   __attribute__ ((__nonnull__ (1, 3, 5)));
  53
  54 /* Read multiple blocks from the overlay or plugin. */
  55 extern int blk_read_multiple (nbdkit_next *next,
  56                               uint64_t blknum, uint64_t nrblocks,
  57                               uint8_t *block,
  58                               bool cow_on_read, int *err)
  59   __attribute__ ((__nonnull__ (1, 4, 6)));
  60
  61 /* Cache mode for blocks not already in overlay */
  62 enum cache_mode {
  63   BLK_CACHE_IGNORE,      /* Do nothing */
  64   BLK_CACHE_PASSTHROUGH, /* Make cache request to plugin */
  65   BLK_CACHE_READ,        /* Make ignored read request to plugin */
  66   BLK_CACHE_COW,         /* Make read request to plugin, and write to overlay */
  67 };
  68
  69 /* Cache a single block from the plugin. */
  70 extern int blk_cache (nbdkit_next *next,
  71                       uint64_t blknum, uint8_t *block, enum cache_mode,
  72                       int *err)
  73   __attribute__ ((__nonnull__ (1, 3, 5)));
  74
  75 /* Write a single block. */
  76 extern int blk_write (uint64_t blknum, const uint8_t *block, int *err)
  77   __attribute__ ((__nonnull__ (2, 3)));
  78
  79 /* Trim a single block. */
  80 extern int blk_trim (uint64_t blknum, int *err)
  81   __attribute__ ((__nonnull__ (2)));
  82
  83 #endif /* NBDKIT_BLK_H */