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-io.h"
  26 #include "block/block_int.h"
  27 #include "qemu/module.h"
  28 #include "qapi/error.h"
  29
  30
  31 static int compress_open(BlockDriverState *bs, QDict *options, int flags,
  32                          Error **errp)
  33 {
  34     int ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
  35     if (ret < 0) {
  36         return ret;
  37     }
  38
  39     if (!bs->file->bs->drv || !block_driver_can_compress(bs->file->bs->drv)) {
  40         error_setg(errp,
  41                    "Compression is not supported for underlying format: %s",
  42                    bdrv_get_format_name(bs->file->bs) ?: "(no format)");
  43
  44         return -ENOTSUP;
  45     }
  46
  47     bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
  48         (BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
  49
  50     bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
  51         ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
  52             bs->file->bs->supported_zero_flags);
  53
  54     return 0;
  55 }
  56
  57
  58 static int64_t coroutine_fn GRAPH_RDLOCK
  59 compress_co_getlength(BlockDriverState *bs)
  60 {
  61     return bdrv_co_getlength(bs->file->bs);
  62 }
  63
  64
  65 static int coroutine_fn GRAPH_RDLOCK
  66 compress_co_preadv_part(BlockDriverState *bs, int64_t offset, int64_t bytes,
  67                         QEMUIOVector *qiov, size_t qiov_offset,
  68                         BdrvRequestFlags flags)
  69 {
  70     return bdrv_co_preadv_part(bs->file, offset, bytes, qiov, qiov_offset,
  71                                flags);
  72 }
  73
  74
  75 static int coroutine_fn GRAPH_RDLOCK
  76 compress_co_pwritev_part(BlockDriverState *bs, int64_t offset, int64_t bytes,
  77                          QEMUIOVector *qiov, size_t qiov_offset,
  78                          BdrvRequestFlags flags)
  79 {
  80     return bdrv_co_pwritev_part(bs->file, offset, bytes, qiov, qiov_offset,
  81                                 flags | BDRV_REQ_WRITE_COMPRESSED);
  82 }
  83
  84
  85 static int coroutine_fn GRAPH_RDLOCK
  86 compress_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes,
  87                           BdrvRequestFlags flags)
  88 {
  89     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
  90 }
  91
  92
  93 static int coroutine_fn GRAPH_RDLOCK
  94 compress_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
  95 {
  96     return bdrv_co_pdiscard(bs->file, offset, bytes);
  97 }
  98
  99
 100 static void compress_refresh_limits(BlockDriverState *bs, Error **errp)
 101 {
 102     BlockDriverInfo bdi;
 103     int ret;
 104
 105     if (!bs->file) {
 106         return;
 107     }
 108
 109     ret = bdrv_get_info(bs->file->bs, &bdi);
 110     if (ret < 0 || bdi.cluster_size == 0) {
 111         return;
 112     }
 113
 114     bs->bl.request_alignment = bdi.cluster_size;
 115 }
 116
 117
 118 static void coroutine_fn GRAPH_RDLOCK
 119 compress_co_eject(BlockDriverState *bs, bool eject_flag)
 120 {
 121     bdrv_co_eject(bs->file->bs, eject_flag);
 122 }
 123
 124
 125 static void coroutine_fn GRAPH_RDLOCK
 126 compress_co_lock_medium(BlockDriverState *bs, bool locked)
 127 {
 128     bdrv_co_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_co_getlength                  = compress_co_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_co_eject                      = compress_co_eject,
 147     .bdrv_co_lock_medium                = compress_co_lock_medium,
 148
 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);