block/quorum.c

   1 /*
   2  * Quorum Block filter
   3  *
   4  * Copyright (C) 2012-2014 Nodalink, EURL.
   5  *
   6  * Author:
   7  *   Benoît Canet <benoit.canet@irqsave.net>
   8  *
   9  * Based on the design and code of blkverify.c (Copyright (C) 2010 IBM, Corp)
  10  * and blkmirror.c (Copyright (C) 2011 Red Hat, Inc).
  11  *
  12  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  13  * See the COPYING file in the top-level directory.
  14  */
  15
  16 #include "block/block_int.h"
  17
  18 typedef struct QuorumAIOCB QuorumAIOCB;
  19
  20 /* Quorum will create one instance of the following structure per operation it
  21  * performs on its children.
  22  * So for each read/write operation coming from the upper layer there will be
  23  * $children_count QuorumChildRequest.
  24  */
  25 typedef struct QuorumChildRequest {
  26     BlockDriverAIOCB *aiocb;
  27     QEMUIOVector qiov;
  28     uint8_t *buf;
  29     int ret;
  30     QuorumAIOCB *parent;
  31 } QuorumChildRequest;
  32
  33 /* Quorum will use the following structure to track progress of each read/write
  34  * operation received by the upper layer.
  35  * This structure hold pointers to the QuorumChildRequest structures instances
  36  * used to do operations on each children and track overall progress.
  37  */
  38 struct QuorumAIOCB {
  39     BlockDriverAIOCB common;
  40
  41     /* Request metadata */
  42     uint64_t sector_num;
  43     int nb_sectors;
  44
  45     QEMUIOVector *qiov;         /* calling IOV */
  46
  47     QuorumChildRequest *qcrs;   /* individual child requests */
  48     int count;                  /* number of completed AIOCB */
  49     int success_count;          /* number of successfully completed AIOCB */
  50
  51     bool is_read;
  52     int vote_ret;
  53 };