From: Max Reitz <mre...@redhat.com>
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 <mre...@redhat.com>
Message-id: 20180421132929.21610-2-mre...@redhat.com
Reviewed-by: Alberto Garcia <be...@igalia.com>
Reviewed-by: Kevin Wolf <kw...@redhat.com>
Signed-off-by: Max Reitz <mre...@redhat.com>
---
qapi/block-core.json | 5 +-
block/copy-on-read.c | 171 +++++++++++++++++++++++++++++++++++++++++++++++++++
block/Makefile.objs | 2 +-
3 files changed, 176 insertions(+), 2 deletions(-)
create mode 100644 block/copy-on-read.c
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 17ffd44cce..55728cb823 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -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',
diff --git a/block/copy-on-read.c b/block/copy-on-read.c
new file mode 100644
index 0000000000..823ec751c4
--- /dev/null
+++ b/block/copy-on-read.c
@@ -0,0 +1,171 @@
+/*
+ * Copy-on-read filter block driver
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * Author:
+ * Max Reitz <mre...@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);
diff --git a/block/Makefile.objs b/block/Makefile.objs
index d644bac60a..899bfb5e2c 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -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
--
2.13.6
