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     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
  59 static int64_t compress_getlength(BlockDriverState *bs)
  60 {
  61     return bdrv_getlength(bs->file->bs);
  62 }
  63
  64
  65 static int coroutine_fn compress_co_preadv_part(BlockDriverState *bs,
  66                                                 uint64_t offset, uint64_t bytes,
  67                                                 QEMUIOVector *qiov,
  68                                                 size_t qiov_offset,
  69                                                 int flags)
  70 {
  71     return bdrv_co_preadv_part(bs->file, offset, bytes, qiov, qiov_offset,
  72                                flags);
  73 }
  74
  75
  76 static int coroutine_fn compress_co_pwritev_part(BlockDriverState *bs,
  77                                                  uint64_t offset,
  78                                                  uint64_t bytes,
  79                                                  QEMUIOVector *qiov,
  80                                                  size_t qiov_offset, int flags)
  81 {
  82     return bdrv_co_pwritev_part(bs->file, offset, bytes, qiov, qiov_offset,
  83                                 flags | BDRV_REQ_WRITE_COMPRESSED);
  84 }
  85
  86
  87 static int coroutine_fn compress_co_pwrite_zeroes(BlockDriverState *bs,
  88                                                   int64_t offset, int bytes,
  89                                                   BdrvRequestFlags flags)
  90 {
  91     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
  92 }
  93
  94
  95 static int coroutine_fn compress_co_pdiscard(BlockDriverState *bs,
  96                                              int64_t offset, int bytes)
  97 {
  98     return bdrv_co_pdiscard(bs->file, offset, bytes);
  99 }
 100
 101
 102 static void compress_refresh_limits(BlockDriverState *bs, Error **errp)
 103 {
 104     BlockDriverInfo bdi;
 105     int ret;
 106
 107     if (!bs->file) {
 108         return;
 109     }
 110
 111     ret = bdrv_get_info(bs->file->bs, &bdi);
 112     if (ret < 0 || bdi.cluster_size == 0) {
 113         return;
 114     }
 115
 116     bs->bl.request_alignment = bdi.cluster_size;
 117 }
 118
 119
 120 static void compress_eject(BlockDriverState *bs, bool eject_flag)
 121 {
 122     bdrv_eject(bs->file->bs, eject_flag);
 123 }
 124
 125
 126 static void compress_lock_medium(BlockDriverState *bs, bool locked)
 127 {
 128     bdrv_lock_medium(bs->file->bs, locked);
 129 }
 130
 131
 132 static BlockDriver bdrv_compress = {
 133     .format_name                        = "compress",
 134
 135     .bdrv_open                          = compress_open,
 136     .bdrv_child_perm                    = bdrv_default_perms,
 137
 138     .bdrv_getlength                     = compress_getlength,
 139
 140     .bdrv_co_preadv_part                = compress_co_preadv_part,
 141     .bdrv_co_pwritev_part               = compress_co_pwritev_part,
 142     .bdrv_co_pwrite_zeroes              = compress_co_pwrite_zeroes,
 143     .bdrv_co_pdiscard                   = compress_co_pdiscard,
 144     .bdrv_refresh_limits                = compress_refresh_limits,
 145
 146     .bdrv_eject                         = compress_eject,
 147     .bdrv_lock_medium                   = compress_lock_medium,
 148
 149     .has_variable_length                = true,
 150     .is_filter                          = true,
 151 };
 152
 153 static void bdrv_compress_init(void)
 154 {
 155     bdrv_register(&bdrv_compress);
 156 }
 157
 158 block_init(bdrv_compress_init);