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
  30 static int compress_open(BlockDriverState *bs, QDict *options, int flags,
  31                          Error **errp)
  32 {
  33     int ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
  34     if (ret < 0) {
  35         return ret;
  36     }
  37
  38     if (!bs->file->bs->drv || !block_driver_can_compress(bs->file->bs->drv)) {
  39         error_setg(errp,
  40                    "Compression is not supported for underlying format: %s",
  41                    bdrv_get_format_name(bs->file->bs) ?: "(no format)");
  42
  43         return -ENOTSUP;
  44     }
  45
  46     bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
  47         (BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
  48
  49     bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
  50         ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
  51             bs->file->bs->supported_zero_flags);
  52
  53     return 0;
  54 }
  55
  56
  57 static int64_t compress_getlength(BlockDriverState *bs)
  58 {
  59     return bdrv_getlength(bs->file->bs);
  60 }
  61
  62
  63 static int coroutine_fn compress_co_preadv_part(BlockDriverState *bs,
  64                                                 int64_t offset, int64_t bytes,
  65                                                 QEMUIOVector *qiov,
  66                                                 size_t qiov_offset,
  67                                                 BdrvRequestFlags flags)
  68 {
  69     return bdrv_co_preadv_part(bs->file, offset, bytes, qiov, qiov_offset,
  70                                flags);
  71 }
  72
  73
  74 static int coroutine_fn compress_co_pwritev_part(BlockDriverState *bs,
  75                                                  int64_t offset,
  76                                                  int64_t bytes,
  77                                                  QEMUIOVector *qiov,
  78                                                  size_t qiov_offset,
  79                                                  BdrvRequestFlags flags)
  80 {
  81     return bdrv_co_pwritev_part(bs->file, offset, bytes, qiov, qiov_offset,
  82                                 flags | BDRV_REQ_WRITE_COMPRESSED);
  83 }
  84
  85
  86 static int coroutine_fn compress_co_pwrite_zeroes(BlockDriverState *bs,
  87                                                   int64_t offset, int64_t bytes,
  88                                                   BdrvRequestFlags flags)
  89 {
  90     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
  91 }
  92
  93
  94 static int coroutine_fn compress_co_pdiscard(BlockDriverState *bs,
  95                                              int64_t offset, int64_t bytes)
  96 {
  97     return bdrv_co_pdiscard(bs->file, offset, bytes);
  98 }
  99
 100
 101 static void compress_refresh_limits(BlockDriverState *bs, Error **errp)
 102 {
 103     BlockDriverInfo bdi;
 104     int ret;
 105
 106     if (!bs->file) {
 107         return;
 108     }
 109
 110     ret = bdrv_get_info(bs->file->bs, &bdi);
 111     if (ret < 0 || bdi.cluster_size == 0) {
 112         return;
 113     }
 114
 115     bs->bl.request_alignment = bdi.cluster_size;
 116 }
 117
 118
 119 static void compress_eject(BlockDriverState *bs, bool eject_flag)
 120 {
 121     bdrv_eject(bs->file->bs, eject_flag);
 122 }
 123
 124
 125 static void compress_lock_medium(BlockDriverState *bs, bool locked)
 126 {
 127     bdrv_lock_medium(bs->file->bs, locked);
 128 }
 129
 130
 131 static BlockDriver bdrv_compress = {
 132     .format_name                        = "compress",
 133
 134     .bdrv_open                          = compress_open,
 135     .bdrv_child_perm                    = bdrv_default_perms,
 136
 137     .bdrv_getlength                     = compress_getlength,
 138
 139     .bdrv_co_preadv_part                = compress_co_preadv_part,
 140     .bdrv_co_pwritev_part               = compress_co_pwritev_part,
 141     .bdrv_co_pwrite_zeroes              = compress_co_pwrite_zeroes,
 142     .bdrv_co_pdiscard                   = compress_co_pdiscard,
 143     .bdrv_refresh_limits                = compress_refresh_limits,
 144
 145     .bdrv_eject                         = compress_eject,
 146     .bdrv_lock_medium                   = compress_lock_medium,
 147
 148     .has_variable_length                = true,
 149     .is_filter                          = true,
 150 };
 151
 152 static void bdrv_compress_init(void)
 153 {
 154     bdrv_register(&bdrv_compress);
 155 }
 156
 157 block_init(bdrv_compress_init);