qemu/block/filter-compress.c
Kevin Wolf a4b740db5e block: Take graph lock for most of .bdrv_open
Most implementations of .bdrv_open first open their file child (which is
an operation that internally takes the write lock and therefore we
shouldn't hold the graph lock while calling it), and afterwards many
operations that require holding the graph lock, e.g. for accessing
bs->file.

This changes block drivers that follow this pattern to take the graph
lock after opening the child node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-24-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-11-08 17:56:18 +01:00

161 lines
4.6 KiB
C

/*
* Compress filter block driver
*
* Copyright (c) 2019 Virtuozzo International GmbH
*
* Author:
* Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
* (based on block/copy-on-read.c by Max Reitz)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 or
* (at your option) any later version of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "block/block-io.h"
#include "block/block_int.h"
#include "qemu/module.h"
#include "qapi/error.h"
static int compress_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
int ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
if (ret < 0) {
return ret;
}
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (!bs->file->bs->drv || !block_driver_can_compress(bs->file->bs->drv)) {
error_setg(errp,
"Compression is not supported for underlying format: %s",
bdrv_get_format_name(bs->file->bs) ?: "(no format)");
return -ENOTSUP;
}
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
(BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
bs->file->bs->supported_zero_flags);
return 0;
}
static int64_t coroutine_fn GRAPH_RDLOCK
compress_co_getlength(BlockDriverState *bs)
{
return bdrv_co_getlength(bs->file->bs);
}
static int coroutine_fn GRAPH_RDLOCK
compress_co_preadv_part(BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
return bdrv_co_preadv_part(bs->file, offset, bytes, qiov, qiov_offset,
flags);
}
static int coroutine_fn GRAPH_RDLOCK
compress_co_pwritev_part(BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
return bdrv_co_pwritev_part(bs->file, offset, bytes, qiov, qiov_offset,
flags | BDRV_REQ_WRITE_COMPRESSED);
}
static int coroutine_fn GRAPH_RDLOCK
compress_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes,
BdrvRequestFlags flags)
{
return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
}
static int coroutine_fn GRAPH_RDLOCK
compress_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
{
return bdrv_co_pdiscard(bs->file, offset, bytes);
}
static void GRAPH_RDLOCK
compress_refresh_limits(BlockDriverState *bs, Error **errp)
{
BlockDriverInfo bdi;
int ret;
if (!bs->file) {
return;
}
ret = bdrv_get_info(bs->file->bs, &bdi);
if (ret < 0 || bdi.cluster_size == 0) {
return;
}
bs->bl.request_alignment = bdi.cluster_size;
}
static void coroutine_fn GRAPH_RDLOCK
compress_co_eject(BlockDriverState *bs, bool eject_flag)
{
bdrv_co_eject(bs->file->bs, eject_flag);
}
static void coroutine_fn GRAPH_RDLOCK
compress_co_lock_medium(BlockDriverState *bs, bool locked)
{
bdrv_co_lock_medium(bs->file->bs, locked);
}
static BlockDriver bdrv_compress = {
.format_name = "compress",
.bdrv_open = compress_open,
.bdrv_child_perm = bdrv_default_perms,
.bdrv_co_getlength = compress_co_getlength,
.bdrv_co_preadv_part = compress_co_preadv_part,
.bdrv_co_pwritev_part = compress_co_pwritev_part,
.bdrv_co_pwrite_zeroes = compress_co_pwrite_zeroes,
.bdrv_co_pdiscard = compress_co_pdiscard,
.bdrv_refresh_limits = compress_refresh_limits,
.bdrv_co_eject = compress_co_eject,
.bdrv_co_lock_medium = compress_co_lock_medium,
.is_filter = true,
};
static void bdrv_compress_init(void)
{
bdrv_register(&bdrv_compress);
}
block_init(bdrv_compress_init);