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Re: [Qemu-block] [RFC PATCH COLO v2 09/13] block: Parse "backing_referen
From: |
Fam Zheng |
Subject: |
Re: [Qemu-block] [RFC PATCH COLO v2 09/13] block: Parse "backing_reference" option to reference existing BDS |
Date: |
Thu, 26 Mar 2015 15:31:15 +0800 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Wed, 03/25 17:36, Wen Congyang wrote:
> Usage:
> -drive file=xxx,id=Y, \
> -drive
> file=xxxx,id=X,backing_reference.drive_id=Y,backing_reference.hidden-disk.*
>
> It will create such backing chain:
> {virtio-blk dev 'Y'}
> {virtio-blk dev 'X'}
> |
> |
> |
> |
> v
> v
>
> [base] <- [mid] <- ( Y ) <----------------- (hidden target)
> <--------------- ( X )
>
> v ^
> v ^
> v ^
> v ^
> >>>> drive-backup sync=none >>>>
>
> X's backing file is hidden-disk, and hidden-disk's backing file is Y.
> Disk Y may be opened or reopened in read-write mode, so A block backup
> job is automatically created: source is Y and target is hidden-disk.
>
> Signed-off-by: Wen Congyang <address@hidden>
> Signed-off-by: zhanghailiang <address@hidden>
> Signed-off-by: Gonglei <address@hidden>
> ---
> block.c | 145
> ++++++++++++++++++++++++++++++++++++++++++++-
> include/block/block.h | 1 +
> include/block/block_int.h | 1 +
> tests/qemu-iotests/051 | 13 ++++
> tests/qemu-iotests/051.out | 13 ++++
> 5 files changed, 170 insertions(+), 3 deletions(-)
>
> diff --git a/block.c b/block.c
> index b4d629e..bd7fa9c 100644
> --- a/block.c
> +++ b/block.c
> @@ -1351,6 +1351,113 @@ free_exit:
> return ret;
> }
>
> +static void backing_reference_completed(void *opaque, int ret)
> +{
> + BlockDriverState *hidden_disk = opaque;
> +
> + assert(!hidden_disk->backing_reference);
> +}
> +
> +static int bdrv_open_backing_reference_file(BlockDriverState *bs,
> + QDict *options, Error **errp)
> +{
> + const char *backing_name;
> + QDict *hidden_disk_options = NULL;
> + BlockDriverState *backing_hd, *hidden_disk;
> + BlockBackend *backing_blk;
> + Error *local_err = NULL;
> + int ret = 0;
> +
> + backing_name = qdict_get_try_str(options, "drive_id");
> + if (!backing_name) {
> + error_setg(errp, "Backing reference needs option drive_id");
> + ret = -EINVAL;
> + goto free_exit;
> + }
> + qdict_del(options, "drive_id");
> +
> + qdict_extract_subqdict(options, &hidden_disk_options, "hidden-disk.");
> + if (!qdict_size(hidden_disk_options)) {
> + error_setg(errp, "Backing reference needs option hidden-disk.*");
> + ret = -EINVAL;
> + goto free_exit;
> + }
> +
> + if (qdict_size(options)) {
> + const QDictEntry *entry = qdict_first(options);
> + error_setg(errp, "Backing reference used by '%s' doesn't support "
> + "the option '%s'", bdrv_get_device_name(bs), entry->key);
> + ret = -EINVAL;
> + goto free_exit;
> + }
> +
> + backing_blk = blk_by_name(backing_name);
> + if (!backing_blk) {
> + error_set(errp, QERR_DEVICE_NOT_FOUND, backing_name);
> + ret = -ENOENT;
> + goto free_exit;
> + }
> +
> + backing_hd = blk_bs(backing_blk);
> + /* Backing reference itself? */
> + if (backing_hd == bs || bdrv_find_overlay(backing_hd, bs)) {
> + error_setg(errp, "Backing reference itself");
> + ret = -EINVAL;
> + goto free_exit;
> + }
> +
> + if (bdrv_op_is_blocked(backing_hd, BLOCK_OP_TYPE_BACKING_REFERENCE,
> + errp)) {
> + ret = -EBUSY;
> + goto free_exit;
> + }
> +
> + /* hidden-disk is bs's backing file */
> + ret = bdrv_open_backing_file(bs, hidden_disk_options, errp);
> + hidden_disk_options = NULL;
> + if (ret < 0) {
> + goto free_exit;
> + }
> +
> + hidden_disk = bs->backing_hd;
> + if (!hidden_disk->drv || !hidden_disk->drv->supports_backing) {
> + ret = -EINVAL;
> + error_setg(errp, "Hidden disk's driver doesn't support backing
> files");
> + goto free_exit;
> + }
> +
> + bdrv_set_backing_hd(hidden_disk, backing_hd);
> + bdrv_ref(backing_hd);
> +
> + /*
> + * backing hd may be opened or reopened in read-write mode, so we
> + * should backup backing hd to hidden disk
> + */
> + bdrv_op_unblock(hidden_disk, BLOCK_OP_TYPE_BACKUP_TARGET,
> + bs->backing_blocker);
> + bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
> + hidden_disk->backing_blocker);
> +
> + bdrv_ref(hidden_disk);
> + backup_start(backing_hd, hidden_disk, 0, MIRROR_SYNC_MODE_NONE,
> + BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
> + backing_reference_completed, hidden_disk, &local_err);
We need to be careful, the backing_hd may not be safe to access, depending on
which AioContext it is running on. At least, we should make sure bs,
hidden_disk and backing_hd are all on the same AioContext.
Here, before accessing backing_hd, we need to call aio_context_acquire, like in
qmp_drive_backup.
Fam
> + if (local_err) {
> + error_propagate(errp, local_err);
> + bdrv_unref(hidden_disk);
> + /* FIXME, use which errno? */
> + ret = -EIO;
> + goto free_exit;
> + }
> +
> + bs->backing_reference = true;
> +
> +free_exit:
> + QDECREF(hidden_disk_options);
> + QDECREF(options);
> + return ret;
> +}
> +
> /*
> * Opens a disk image whose options are given as BlockdevRef in another block
> * device's options.
> @@ -1604,13 +1711,37 @@ int bdrv_open(BlockDriverState **pbs, const char
> *filename,
>
> /* If there is a backing file, use it */
> if ((flags & BDRV_O_NO_BACKING) == 0) {
> - QDict *backing_options;
> + QDict *backing_options, *backing_reference_options;
>
> + qdict_extract_subqdict(options, &backing_reference_options,
> + "backing_reference.");
> qdict_extract_subqdict(options, &backing_options, "backing.");
> - ret = bdrv_open_backing_file(bs, backing_options, &local_err);
> - if (ret < 0) {
> +
> + if (qdict_size(backing_reference_options) &&
> + qdict_size(backing_options)) {
> + error_setg(&local_err,
> + "Option \"backing_reference.*\" and \"backing.*\""
> + " cannot be used together");
> + ret = -EINVAL;
> + QDECREF(backing_reference_options);
> + QDECREF(backing_options);
> goto close_and_fail;
> }
> + if (qdict_size(backing_reference_options)) {
> + QDECREF(backing_options);
> + ret = bdrv_open_backing_reference_file(bs,
> + backing_reference_options,
> + &local_err);
> + if (ret) {
> + goto close_and_fail;
> + }
> + } else {
> + QDECREF(backing_reference_options);
> + ret = bdrv_open_backing_file(bs, backing_options, &local_err);
> + if (ret < 0) {
> + goto close_and_fail;
> + }
> + }
> }
>
> bdrv_refresh_filename(bs);
> @@ -1941,6 +2072,14 @@ void bdrv_close(BlockDriverState *bs)
> if (bs->drv) {
> if (bs->backing_hd) {
> BlockDriverState *backing_hd = bs->backing_hd;
> + if (bs->backing_reference) {
> + assert(backing_hd->backing_hd);
> + if (backing_hd->backing_hd->job) {
> + block_job_cancel(backing_hd->backing_hd->job);
> + }
> + bdrv_set_backing_hd(backing_hd, NULL);
> + bdrv_unref(backing_hd->backing_hd);
> + }
> bdrv_set_backing_hd(bs, NULL);
> bdrv_unref(backing_hd);
> }
> diff --git a/include/block/block.h b/include/block/block.h
> index 68f3b1a..7138e90 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -159,6 +159,7 @@ typedef enum BlockOpType {
> BLOCK_OP_TYPE_RESIZE,
> BLOCK_OP_TYPE_STREAM,
> BLOCK_OP_TYPE_REPLACE,
> + BLOCK_OP_TYPE_BACKING_REFERENCE,
> BLOCK_OP_TYPE_MAX,
> } BlockOpType;
>
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 08dd8ba..624945d 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -375,6 +375,7 @@ struct BlockDriverState {
> QDict *full_open_options;
> char exact_filename[PATH_MAX];
>
> + bool backing_reference;
> BlockDriverState *backing_hd;
> BlockDriverState *file;
>
> diff --git a/tests/qemu-iotests/051 b/tests/qemu-iotests/051
> index 0360f37..fd67f40 100755
> --- a/tests/qemu-iotests/051
> +++ b/tests/qemu-iotests/051
> @@ -116,6 +116,19 @@ run_qemu -drive
> file="$TEST_IMG",file.backing.driver=file,file.backing.filename=
> run_qemu -drive
> file="$TEST_IMG",file.backing.driver=qcow2,file.backing.file.filename="$TEST_IMG.orig"
>
> echo
> +echo === Backing file reference ===
> +echo
> +
> +run_qemu -drive file="$TEST_IMG",if=none,id=drive0 \
> + -drive
> file="$TEST_IMG",driver=qcow2,backing_reference.drive_id=drive0,backing_reference.hidden-disk.filename="$TEST_IMG.hidden"
> +
> +run_qemu -drive file="$TEST_IMG",if=none,id=drive0 \
> + -drive
> file="$TEST_IMG",driver=qcow2,backing_reference.drive_id=drive0,backing_reference.hidden-disk.filename="$TEST_IMG.hidden",backing.file.filename="$TEST_IMG.orig"
> +
> +run_qemu -drive file="$TEST_IMG",if=none,id=drive0 \
> + -drive
> file="$TEST_IMG",driver=qcow2,file.backing_reference.drive_id=drive0,file.backing_reference.hidden-disk.filename="$TEST_IMG.hidden",file.backing.file.filename="$TEST_IMG.orig"
> +
> +echo
> echo === Enable and disable lazy refcounting on the command line, plus some
> invalid values ===
> echo
>
> diff --git a/tests/qemu-iotests/051.out b/tests/qemu-iotests/051.out
> index 2890eac..cb8340b 100644
> --- a/tests/qemu-iotests/051.out
> +++ b/tests/qemu-iotests/051.out
> @@ -75,6 +75,19 @@ Testing: -drive
> file=TEST_DIR/t.qcow2,file.backing.driver=qcow2,file.backing.fil
> QEMU_PROG: -drive
> file=TEST_DIR/t.qcow2,file.backing.driver=qcow2,file.backing.file.filename=TEST_DIR/t.qcow2.orig:
> Driver doesn't support backing files
>
>
> +=== Backing file reference ===
> +
> +Testing: -drive file=TEST_DIR/t.qcow2,if=none,id=drive0 -drive
> file=TEST_DIR/t.qcow2,driver=qcow2,backing_reference.drive_id=drive0,backing_reference.hidden-disk.filename=TEST_DIR/t.qcow2.hidden
> +QEMU X.Y.Z monitor - type 'help' for more information
> +(qemu) q[K[Dqu[K[D[Dqui[K[D[D[Dquit[K
> +
> +Testing: -drive file=TEST_DIR/t.qcow2,if=none,id=drive0 -drive
> file=TEST_DIR/t.qcow2,driver=qcow2,backing_reference.drive_id=drive0,backing_reference.hidden-disk.filename=TEST_DIR/t.qcow2.hidden,backing.file.filename=TEST_DIR/t.qcow2.orig
> +QEMU_PROG: -drive
> file=TEST_DIR/t.qcow2,driver=qcow2,backing=drive0,backing.file.filename=TEST_DIR/t.qcow2.orig:
> Option "backing_reference.*" and "backing.*" cannot be used together
> +
> +Testing: -drive file=TEST_DIR/t.qcow2,if=none,id=drive0 -drive
> file=TEST_DIR/t.qcow2,driver=qcow2,file.backing_reference.drive_id=drive0,file.backing_reference.hidden-disk.filename=TEST_DIR/t.qcow2.hidden,file.backing.file.filename=TEST_DIR/t.qcow2.orig
> +QEMU_PROG: -drive
> file=TEST_DIR/t.qcow2,driver=qcow2,file.backing=drive0,file.backing.file.filename=TEST_DIR/t.qcow2.orig:
> Option "backing_reference.*" and "backing.*" cannot be used together
> +
> +
> === Enable and disable lazy refcounting on the command line, plus some
> invalid values ===
>
> Testing: -drive file=TEST_DIR/t.qcow2,format=qcow2,lazy-refcounts=on
> --
> 2.1.0
>
- Re: [Qemu-block] [RFC PATCH COLO v2 08/13] Allow creating backup jobs when opening BDS, (continued)
[Qemu-block] [RFC PATCH COLO v2 10/13] Backup: clear all bitmap when doing block checkpoint, Wen Congyang, 2015/03/25
[Qemu-block] [RFC PATCH COLO v2 07/13] allow writing to the backing file, Wen Congyang, 2015/03/25
[Qemu-block] [RFC PATCH COLO v2 09/13] block: Parse "backing_reference" option to reference existing BDS, Wen Congyang, 2015/03/25
- Re: [Qemu-block] [RFC PATCH COLO v2 09/13] block: Parse "backing_reference" option to reference existing BDS,
Fam Zheng <=
[Qemu-block] [RFC PATCH COLO v2 12/13] skip nbd_target when starting block replication, Wen Congyang, 2015/03/25
[Qemu-block] [RFC PATCH COLO v2 13/13] Don't allow a disk use backing reference target, Wen Congyang, 2015/03/25
[Qemu-block] [RFC PATCH COLO v2 11/13] qcow2: support colo, Wen Congyang, 2015/03/25
Re: [Qemu-block] [RFC PATCH COLO v2 00/13] Block replication for continuous checkpoints, Paolo Bonzini, 2015/03/25
Re: [Qemu-block] [RFC PATCH COLO v2 00/13] Block replication for continuous checkpoints, Dr. David Alan Gilbert, 2015/03/25