LXR qemu/block/filter-compress.c

   1/*
   2 * Compress filter block driver
   3 *
   4 * Copyright (c) 2019 Virtuozzo International GmbH
   5 *
   6 * Author:
   7 *   Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
   8 *   (based on block/copy-on-read.c by Max Reitz)
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public License as
  12 * published by the Free Software Foundation; either version 2 or
  13 * (at your option) any later version of the License.
  14 *
  15 * This program is distributed in the hope that it will be useful,
  16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 * GNU General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU General Public License
  21 * along with this program; if not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24#include "qemu/osdep.h"
  25#include "block/block_int.h"
  26#include "qemu/module.h"
  27#include "qapi/error.h"
  28
  29
  30static int compress_open(BlockDriverState *bs, QDict *options, int flags,
  31                         Error **errp)
  32{
  33    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
  34                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
  35                               false, errp);
  36    if (!bs->file) {
  37        return -EINVAL;
  38    }
  39
  40    if (!bs->file->bs->drv || !block_driver_can_compress(bs->file->bs->drv)) {
  41        error_setg(errp,
  42                   "Compression is not supported for underlying format: %s",
  43                   bdrv_get_format_name(bs->file->bs) ?: "(no format)");
  44
  45        return -ENOTSUP;
  46    }
  47
  48    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
  49        (BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
  50
  51    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
  52        ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
  53            bs->file->bs->supported_zero_flags);
  54
  55    return 0;
  56}
  57
  58
  59static int64_t compress_getlength(BlockDriverState *bs)
  60{
  61    return bdrv_getlength(bs->file->bs);
  62}
  63
  64
  65static int coroutine_fn compress_co_preadv_part(BlockDriverState *bs,
  66                                                int64_t offset, int64_t bytes,
  67                                                QEMUIOVector *qiov,
  68                                                size_t qiov_offset,
  69                                                BdrvRequestFlags flags)
  70{
  71    return bdrv_co_preadv_part(bs->file, offset, bytes, qiov, qiov_offset,
  72                               flags);
  73}
  74
  75
  76static int coroutine_fn compress_co_pwritev_part(BlockDriverState *bs,
  77                                                 int64_t offset,
  78                                                 int64_t bytes,
  79                                                 QEMUIOVector *qiov,
  80                                                 size_t qiov_offset,
  81                                                 BdrvRequestFlags flags)
  82{
  83    return bdrv_co_pwritev_part(bs->file, offset, bytes, qiov, qiov_offset,
  84                                flags | BDRV_REQ_WRITE_COMPRESSED);
  85}
  86
  87
  88static int coroutine_fn compress_co_pwrite_zeroes(BlockDriverState *bs,
  89                                                  int64_t offset, int64_t bytes,
  90                                                  BdrvRequestFlags flags)
  91{
  92    return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
  93}
  94
  95
  96static int coroutine_fn compress_co_pdiscard(BlockDriverState *bs,
  97                                             int64_t offset, int64_t bytes)
  98{
  99    return bdrv_co_pdiscard(bs->file, offset, bytes);
 100}
 101
 102
 103static void compress_refresh_limits(BlockDriverState *bs, Error **errp)
 104{
 105    BlockDriverInfo bdi;
 106    int ret;
 107
 108    if (!bs->file) {
 109        return;
 110    }
 111
 112    ret = bdrv_get_info(bs->file->bs, &bdi);
 113    if (ret < 0 || bdi.cluster_size == 0) {
 114        return;
 115    }
 116
 117    bs->bl.request_alignment = bdi.cluster_size;
 118}
 119
 120
 121static void compress_eject(BlockDriverState *bs, bool eject_flag)
 122{
 123    bdrv_eject(bs->file->bs, eject_flag);
 124}
 125
 126
 127static void compress_lock_medium(BlockDriverState *bs, bool locked)
 128{
 129    bdrv_lock_medium(bs->file->bs, locked);
 130}
 131
 132
 133static BlockDriver bdrv_compress = {
 134    .format_name                        = "compress",
 135
 136    .bdrv_open                          = compress_open,
 137    .bdrv_child_perm                    = bdrv_default_perms,
 138
 139    .bdrv_getlength                     = compress_getlength,
 140
 141    .bdrv_co_preadv_part                = compress_co_preadv_part,
 142    .bdrv_co_pwritev_part               = compress_co_pwritev_part,
 143    .bdrv_co_pwrite_zeroes              = compress_co_pwrite_zeroes,
 144    .bdrv_co_pdiscard                   = compress_co_pdiscard,
 145    .bdrv_refresh_limits                = compress_refresh_limits,
 146
 147    .bdrv_eject                         = compress_eject,
 148    .bdrv_lock_medium                   = compress_lock_medium,
 149
 150    .has_variable_length                = true,
 151    .is_filter                          = true,
 152};
 153
 154static void bdrv_compress_init(void)
 155{
 156    bdrv_register(&bdrv_compress);
 157}
 158
 159block_init(bdrv_compress_init);
 160