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block: Add COR filter driver

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This adds a simple copy-on-read filter driver.  It relies on the already
existing COR functionality in the central block layer code, which may be
moved here once we no longer need it there.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180421132929.21610-2-mreitz@redhat.com
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2018-04-21 15:29:21 +02:00
parent b05a2225d2
commit 6c6f24fd84
3 changed files with 176 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
block/Makefile.objs
View File

@ -26,7 +26,7 @@ block-obj-y += accounting.o dirty-bitmap.o
block-obj-y += write-threshold.o
block-obj-y += backup.o
block-obj-$(CONFIG_REPLICATION) += replication.o
block-obj-y += throttle.o
block-obj-y += throttle.o copy-on-read.o
block-obj-y += crypto.o

171
block/copy-on-read.c Normal file
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@ -0,0 +1,171 @@
/*
* Copy-on-read filter block driver
*
* Copyright (c) 2018 Red Hat, Inc.
*
* Author:
* Max Reitz <mreitz@redhat.com>
*
* 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) version 3 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_int.h"
static int cor_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false,
errp);
if (!bs->file) {
return -EINVAL;
}
bs->supported_write_flags = BDRV_REQ_FUA &
bs->file->bs->supported_write_flags;
bs->supported_zero_flags = (BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &
bs->file->bs->supported_zero_flags;
return 0;
}
static void cor_close(BlockDriverState *bs)
{
}
#define PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
| BLK_PERM_WRITE \
| BLK_PERM_RESIZE)
#define PERM_UNCHANGED (BLK_PERM_ALL & ~PERM_PASSTHROUGH)
static void cor_child_perm(BlockDriverState *bs, BdrvChild *c,
const BdrvChildRole *role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
if (c == NULL) {
*nperm = (perm & PERM_PASSTHROUGH) | BLK_PERM_WRITE_UNCHANGED;
*nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED;
return;
}
*nperm = (perm & PERM_PASSTHROUGH) |
(c->perm & PERM_UNCHANGED);
*nshared = (shared & PERM_PASSTHROUGH) |
(c->shared_perm & PERM_UNCHANGED);
}
static int64_t cor_getlength(BlockDriverState *bs)
{
return bdrv_getlength(bs->file->bs);
}
static int cor_truncate(BlockDriverState *bs, int64_t offset,
PreallocMode prealloc, Error **errp)
{
return bdrv_truncate(bs->file, offset, prealloc, errp);
}
static int coroutine_fn cor_co_preadv(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
return bdrv_co_preadv(bs->file, offset, bytes, qiov,
flags | BDRV_REQ_COPY_ON_READ);
}
static int coroutine_fn cor_co_pwritev(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
}
static int coroutine_fn cor_co_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int bytes,
BdrvRequestFlags flags)
{
return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
}
static int coroutine_fn cor_co_pdiscard(BlockDriverState *bs,
int64_t offset, int bytes)
{
return bdrv_co_pdiscard(bs->file->bs, offset, bytes);
}
static void cor_eject(BlockDriverState *bs, bool eject_flag)
{
bdrv_eject(bs->file->bs, eject_flag);
}
static void cor_lock_medium(BlockDriverState *bs, bool locked)
{
bdrv_lock_medium(bs->file->bs, locked);
}
static bool cor_recurse_is_first_non_filter(BlockDriverState *bs,
BlockDriverState *candidate)
{
return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
}
BlockDriver bdrv_copy_on_read = {
.format_name = "copy-on-read",
.bdrv_open = cor_open,
.bdrv_close = cor_close,
.bdrv_child_perm = cor_child_perm,
.bdrv_getlength = cor_getlength,
.bdrv_truncate = cor_truncate,
.bdrv_co_preadv = cor_co_preadv,
.bdrv_co_pwritev = cor_co_pwritev,
.bdrv_co_pwrite_zeroes = cor_co_pwrite_zeroes,
.bdrv_co_pdiscard = cor_co_pdiscard,
.bdrv_eject = cor_eject,
.bdrv_lock_medium = cor_lock_medium,
.bdrv_co_block_status = bdrv_co_block_status_from_file,
.bdrv_recurse_is_first_non_filter = cor_recurse_is_first_non_filter,
.has_variable_length = true,
.is_filter = true,
};
static void bdrv_copy_on_read_init(void)
{
bdrv_register(&bdrv_copy_on_read);
}
block_init(bdrv_copy_on_read_init);

5
qapi/block-core.json
View File

@ -2510,11 +2510,12 @@
# @vxhs: Since 2.10
# @throttle: Since 2.11
# @nvme: Since 2.12
# @copy-on-read: Since 2.13
#
# Since: 2.9
##
{ 'enum': 'BlockdevDriver',
'data': [ 'blkdebug', 'blkverify', 'bochs', 'cloop',
'data': [ 'blkdebug', 'blkverify', 'bochs', 'cloop', 'copy-on-read',
'dmg', 'file', 'ftp', 'ftps', 'gluster', 'host_cdrom',
'host_device', 'http', 'https', 'iscsi', 'luks', 'nbd', 'nfs',
'null-aio', 'null-co', 'nvme', 'parallels', 'qcow', 'qcow2', 'qed',
@ -3531,6 +3532,7 @@
'blkverify': 'BlockdevOptionsBlkverify',
'bochs': 'BlockdevOptionsGenericFormat',
'cloop': 'BlockdevOptionsGenericFormat',
'copy-on-read':'BlockdevOptionsGenericFormat',
'dmg': 'BlockdevOptionsGenericFormat',
'file': 'BlockdevOptionsFile',
'ftp': 'BlockdevOptionsCurlFtp',
@ -4058,6 +4060,7 @@
'blkverify': 'BlockdevCreateNotSupported',
'bochs': 'BlockdevCreateNotSupported',
'cloop': 'BlockdevCreateNotSupported',
'copy-on-read': 'BlockdevCreateNotSupported',
'dmg': 'BlockdevCreateNotSupported',
'file': 'BlockdevCreateOptionsFile',
'ftp': 'BlockdevCreateNotSupported',