From: Marcelo Tosatti <mtosa...@redhat.com>
Mirrored writes are used by live block copy.
Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
---
Makefile.objs | 2 +-
block/blkmirror.c | 282 ++++++++++++++++++++++++++++++++++++++++++++++++++++
docs/blkmirror.txt | 15 +++
3 files changed, 298 insertions(+), 1 deletions(-)
create mode 100644 block/blkmirror.c
create mode 100644 docs/blkmirror.txt
diff --git a/Makefile.objs b/Makefile.objs
index 391e524..cd65e1b 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -34,7 +34,7 @@ block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o
dmg.o bochs.o vpc.o vv
block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
qcow2-cache.o
block-nested-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
block-nested-y += qed-check.o
-block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
+block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
blkmirror.o
block-nested-y += stream.o
block-nested-$(CONFIG_WIN32) += raw-win32.o
block-nested-$(CONFIG_POSIX) += raw-posix.o
diff --git a/block/blkmirror.c b/block/blkmirror.c
new file mode 100644
index 0000000..1c02710
--- /dev/null
+++ b/block/blkmirror.c
@@ -0,0 +1,282 @@
+/*
+ * Block driver for mirrored writes.
+ *
+ * Copyright (C) 2011 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <stdarg.h>
+#include "block_int.h"
+
+typedef struct {
+ BlockDriverState *bs[2];
+} BdrvMirrorState;
+
+typedef struct DupAIOCB DupAIOCB;
+
+typedef struct SingleAIOCB {
+ BlockDriverAIOCB *aiocb;
+ int finished;
+ DupAIOCB *parent;
+} SingleAIOCB;
+
+struct DupAIOCB {
+ BlockDriverAIOCB common;
+ int count;
+
+ BlockDriverCompletionFunc *cb;
+ SingleAIOCB aios[2];
+ int ret;
+};
+
+/* Valid blkmirror filenames look like
+ * blkmirror:path/to/image1:path/to/image2 */
+static int blkmirror_open(BlockDriverState *bs, const char *filename, int
flags)
+{
+ BdrvMirrorState *m = bs->opaque;
+ int ret, escape, i, n;
+ char *filename2;
+
+ /* Parse the blkmirror: prefix */
+ if (strncmp(filename, "blkmirror:", strlen("blkmirror:"))) {
+ return -EINVAL;
+ }
+ filename += strlen("blkmirror:");
+
+ /* Parse the raw image filename */
+ filename2 = qemu_malloc(strlen(filename)+1);
+ escape = 0;
+ for (i = n = 0; i < strlen(filename); i++) {
+ if (!escape && filename[i] == ':') {
+ break;
+ }
+ if (!escape && filename[i] == '\\') {
+ escape = 1;
+ } else {
+ escape = 0;
+ }
+
+ if (!escape) {
+ filename2[n++] = filename[i];
+ }
+ }
+ filename2[n] = '\0';
+
+ m->bs[0] = bdrv_new("");
+ if (m->bs[0] == NULL) {
+ free(filename2);
+ return -ENOMEM;
+ }
+ ret = bdrv_open(m->bs[0], filename2, flags, NULL);
+ free(filename2);
+ if (ret < 0) {
+ return ret;
+ }
+ filename += i + 1;
+
+ m->bs[1] = bdrv_new("");
+ if (m->bs[1] == NULL) {
+ bdrv_delete(m->bs[0]);
+ return -ENOMEM;
+ }
+ ret = bdrv_open(m->bs[1], filename, flags, NULL);
+ if (ret < 0) {
+ bdrv_delete(m->bs[0]);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void blkmirror_close(BlockDriverState *bs)
+{
+ BdrvMirrorState *m = bs->opaque;
+ int i;
+
+ for (i = 0; i < 2; i++) {
+ bdrv_delete(m->bs[i]);
+ m->bs[i] = NULL;
+ }
+}
+
+static int blkmirror_flush(BlockDriverState *bs)
+{
+ BdrvMirrorState *m = bs->opaque;
+ int ret;
+
+ ret = bdrv_flush(m->bs[0]);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return bdrv_flush(m->bs[1]);
+}
+
+static int64_t blkmirror_getlength(BlockDriverState *bs)
+{
+ BdrvMirrorState *m = bs->opaque;
+
+ return bdrv_getlength(m->bs[0]);
+}
+
+static BlockDriverAIOCB *blkmirror_aio_readv(BlockDriverState *bs,
+ int64_t sector_num,
+ QEMUIOVector *qiov,
+ int nb_sectors,
+ BlockDriverCompletionFunc *cb,
+ void *opaque)
+{
+ BdrvMirrorState *m = bs->opaque;
+ return bdrv_aio_readv(m->bs[0], sector_num, qiov, nb_sectors, cb, opaque);
+}
+
+static void dup_aio_cancel(BlockDriverAIOCB *blockacb)
+{
+ DupAIOCB *acb = container_of(blockacb, DupAIOCB, common);
+ int i;
+
+ for (i = 0 ; i < 2; i++) {
+ if (!acb->aios[i].finished) {
+ bdrv_aio_cancel(acb->aios[i].aiocb);
+ }
+ }
+ qemu_aio_release(acb);
+}
+
+static AIOPool dup_aio_pool = {
+ .aiocb_size = sizeof(DupAIOCB),
+ .cancel = dup_aio_cancel,
+};
+
+static void blkmirror_aio_cb(void *opaque, int ret)
+{
+ SingleAIOCB *scb = opaque;
+ DupAIOCB *dcb = scb->parent;
+
+ scb->finished = 1;
+ dcb->count--;
+ assert(dcb->count >= 0);
+ if (ret < 0) {
+ dcb->ret = ret;
+ }
+ if (dcb->count == 0) {
+ dcb->common.cb(dcb->common.opaque, dcb->ret);
+ qemu_aio_release(dcb);
+ }
+}
+
+static DupAIOCB *dup_aio_get(BlockDriverState *bs,
+ BlockDriverCompletionFunc *cb,
+ void *opaque)
+{
+ DupAIOCB *dcb;
+ int i;
+
+ dcb = qemu_aio_get(&dup_aio_pool, bs, cb, opaque);
+ if (!dcb) {
+ return NULL;
+ }
+ dcb->count = 2;
+ for (i = 0; i < 2; i++) {
+ dcb->aios[i].parent = dcb;
+ dcb->aios[i].finished = 0;
+ }
+ dcb->ret = 0;
+
+ return dcb;
+}
+
+static BlockDriverAIOCB *blkmirror_aio_writev(BlockDriverState *bs,
+ int64_t sector_num,
+ QEMUIOVector *qiov,
+ int nb_sectors,
+ BlockDriverCompletionFunc *cb,
+ void *opaque)
+{
+ BdrvMirrorState *m = bs->opaque;
+ DupAIOCB *dcb = dup_aio_get(bs, cb, opaque);
+ int i;
+
+ for (i = 0; i < 2; i++) {
+ dcb->aios[i].aiocb = bdrv_aio_writev(m->bs[i], sector_num, qiov,
+ nb_sectors, &blkmirror_aio_cb,
+ &dcb->aios[i]);
+ if (!dcb->aios[i].aiocb) {
+ int a;
+
+ for (a = 0; a < i; a++) {
+ bdrv_aio_cancel(dcb->aios[i].aiocb);
+ }
+ qemu_aio_release(dcb);
+ return NULL;
+ }
+ }
+
+ return &dcb->common;
+}
+
+static BlockDriverAIOCB *blkmirror_aio_flush(BlockDriverState *bs,
+ BlockDriverCompletionFunc *cb,
+ void *opaque)
+{
+ BdrvMirrorState *m = bs->opaque;
+ DupAIOCB *dcb = dup_aio_get(bs, cb, opaque);
+ int i;
+
+ for (i = 0; i < 2; i++) {
+ dcb->aios[i].aiocb = bdrv_aio_flush(m->bs[i], &blkmirror_aio_cb,
+ &dcb->aios[i]);
+ if (!dcb->aios[i].aiocb) {
+ int a;
+
+ for (a = 0; a < i; a++) {
+ bdrv_aio_cancel(dcb->aios[i].aiocb);
+ }
+ qemu_aio_release(dcb);
+ return NULL;
+ }
+ }
+
+ return &dcb->common;
+}
+
+static int blkmirror_discard(BlockDriverState *bs, int64_t sector_num,
+ int nb_sectors)
+{
+ BdrvMirrorState *m = bs->opaque;
+ int ret;
+
+ ret = bdrv_discard(m->bs[0], sector_num, nb_sectors);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return bdrv_discard(m->bs[1], sector_num, nb_sectors);
+}
+
+
+static BlockDriver bdrv_blkmirror = {
+ .format_name = "blkmirror",
+ .protocol_name = "blkmirror",
+ .instance_size = sizeof(BdrvMirrorState),
+
+ .bdrv_getlength = blkmirror_getlength,
+
+ .bdrv_file_open = blkmirror_open,
+ .bdrv_close = blkmirror_close,
+ .bdrv_flush = blkmirror_flush,
+ .bdrv_discard = blkmirror_discard,
+
+ .bdrv_aio_readv = blkmirror_aio_readv,
+ .bdrv_aio_writev = blkmirror_aio_writev,
+ .bdrv_aio_flush = blkmirror_aio_flush,
+};
+
+static void bdrv_blkmirror_init(void)
+{
+ bdrv_register(&bdrv_blkmirror);
+}
+
+block_init(bdrv_blkmirror_init);
diff --git a/docs/blkmirror.txt b/docs/blkmirror.txt
new file mode 100644
index 0000000..202be7d
--- /dev/null
+++ b/docs/blkmirror.txt
@@ -0,0 +1,15 @@
+Block mirror driver
+-------------------
+
+This driver will mirror writes to two distinct images.
+Its used internally by live block copy.
+
+Format
+------
+
+blkmirror:/image1.img:/image2.img
+
+'\' (backslash) can be used to escape colon processing
+as a separator, in the first image filename.
+
+
--
1.7.1
