Commit 554b6147 authored by Alberto Garcia's avatar Alberto Garcia Committed by Kevin Wolf
Browse files

block: Add QMP support for streaming to an intermediate layer 



This patch makes the 'device' parameter of the 'block-stream' command
accept a node name that is not a root node. The presence of this
feature can't be directly tested with introspection; soon we'll
introduce a 'base-node' parameter whose presence can be checked for
this purpose.

In addition to that, operation blockers will be checked in all
intermediate nodes between the top and the base node.

Signed-off-by: default avatarAlberto Garcia <berto@igalia.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 61b49e48

blockdev.c

+9 −6
Original line number Diff line number Diff line
@@ -2937,7 +2937,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device, 
                      bool has_on_error, BlockdevOnError on_error,

                      Error **errp)

{

    BlockDriverState *bs;

    BlockDriverState *bs, *iter;

    BlockDriverState *base_bs = NULL;

    AioContext *aio_context;

    Error *local_err = NULL;
@@ -2947,7 +2947,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device, 
        on_error = BLOCKDEV_ON_ERROR_REPORT;

    }



    bs = qmp_get_root_bs(device, errp);

    bs = bdrv_lookup_bs(device, device, errp);

    if (!bs) {

        return;

    }
@@ -2955,10 +2955,6 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device, 
    aio_context = bdrv_get_aio_context(bs);

    aio_context_acquire(aio_context);



    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_STREAM, errp)) {

        goto out;

    }



    if (has_base) {

        base_bs = bdrv_find_backing_image(bs, base);

        if (base_bs == NULL) {
@@ -2969,6 +2965,13 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device, 
        base_name = base;

    }



    /* Check for op blockers in the whole chain between bs and base */

    for (iter = bs; iter && iter != base_bs; iter = backing_bs(iter)) {

        if (bdrv_op_is_blocked(iter, BLOCK_OP_TYPE_STREAM, errp)) {

            goto out;

        }

    }



    /* if we are streaming the entire chain, the result will have no backing

     * file, and specifying one is therefore an error */

    if (base_bs == NULL && has_backing_file) {

qapi/block-core.json

+10 −3
Original line number Diff line number Diff line
@@ -1464,6 +1464,13 @@ 
# with query-block-jobs.  The operation can be stopped before it has completed

# using the block-job-cancel command.

#

# The node that receives the data is called the top image, can be located in

# any part of the chain (but always above the base image; see below) and can be

# specified using its device or node name. Earlier qemu versions only allowed

# 'device' to name the top level node; presence of the 'base-node' parameter

# during introspection can be used as a witness of the enhanced semantics

# of 'device'.

#

# If a base file is specified then sectors are not copied from that base file and

# its backing chain.  When streaming completes the image file will have the base

# file as its backing file.  This can be used to stream a subset of the backing
@@ -1475,12 +1482,12 @@ 
# @job-id: #optional identifier for the newly-created block job. If

#          omitted, the device name will be used. (Since 2.7)

#

# @device: the device name or node-name of a root node

# @device: the device or node name of the top image

#

# @base:   #optional the common backing file name

#

# @backing-file: #optional The backing file string to write into the active

#                          layer. This filename is not validated.

# @backing-file: #optional The backing file string to write into the top

#                          image. This filename is not validated.

#

#                          If a pathname string is such that it cannot be

#                          resolved by QEMU, that means that subsequent QMP or