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qapi: block-stream: add "bottom" argument

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The code already don't freeze base node and we try to make it prepared
for the situation when base node is changed during the operation. In
other words, block-stream doesn't own base node.

Let's introduce a new interface which should replace the current one,
which will in better relations with the code. Specifying bottom node
instead of base, and requiring it to be non-filter gives us the
following benefits:

 - drop difference between above_base and base_overlay, which will be
   renamed to just bottom, when old interface dropped

 - clean way to work with parallel streams/commits on the same backing
   chain, which otherwise become a problem when we introduce a filter
   for stream job

 - cleaner interface. Nobody will surprised the fact that base node may
   disappear during block-stream, when there is no word about "base" in
   the interface.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201216061703.70908-11-vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2020-12-16 09:17:00 +03:00 committed by Max Reitz
parent 000e5a1cda
commit 7f4a396d76
5 changed files with 94 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
block/monitor/block-hmp-cmds.c
View File

@ -507,7 +507,8 @@ void hmp_block_stream(Monitor *mon, const QDict *qdict)
int64_t speed = qdict_get_try_int(qdict, "speed", 0);
qmp_block_stream(true, device, device, base != NULL, base, false, NULL,
false, NULL, qdict_haskey(qdict, "speed"), speed, true,
false, NULL, false, NULL,
qdict_haskey(qdict, "speed"), speed, true,
BLOCKDEV_ON_ERROR_REPORT, false, NULL, false, false, false,
false, &error);

50
block/stream.c
View File

@ -221,6 +221,7 @@ static const BlockJobDriver stream_job_driver = {
void stream_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *base, const char *backing_file_str,
BlockDriverState *bottom,
int creation_flags, int64_t speed,
BlockdevOnError on_error,
const char *filter_node_name,
@ -230,25 +231,42 @@ void stream_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *iter;
bool bs_read_only;
int basic_flags = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
BlockDriverState *base_overlay = bdrv_find_overlay(bs, base);
BlockDriverState *base_overlay;
BlockDriverState *above_base;
if (!base_overlay) {
error_setg(errp, "'%s' is not in the backing chain of '%s'",
base->node_name, bs->node_name);
return;
}
assert(!(base && bottom));
assert(!(backing_file_str && bottom));
/*
* Find the node directly above @base. @base_overlay is a COW overlay, so
* it must have a bdrv_cow_child(), but it is the immediate overlay of
* @base, so between the two there can only be filters.
*/
above_base = base_overlay;
if (bdrv_cow_bs(above_base) != base) {
above_base = bdrv_cow_bs(above_base);
while (bdrv_filter_bs(above_base) != base) {
above_base = bdrv_filter_bs(above_base);
if (bottom) {
/*
* New simple interface. The code is written in terms of old interface
* with @base parameter (still, it doesn't freeze link to base, so in
* this mean old code is correct for new interface). So, for now, just
* emulate base_overlay and above_base. Still, when old interface
* finally removed, we should refactor code to use only "bottom", but
* not "*base*" things.
*/
assert(!bottom->drv->is_filter);
base_overlay = above_base = bottom;
} else {
base_overlay = bdrv_find_overlay(bs, base);
if (!base_overlay) {
error_setg(errp, "'%s' is not in the backing chain of '%s'",
base->node_name, bs->node_name);
return;
}
/*
* Find the node directly above @base. @base_overlay is a COW overlay,
* so it must have a bdrv_cow_child(), but it is the immediate overlay
* of @base, so between the two there can only be filters.
*/
above_base = base_overlay;
if (bdrv_cow_bs(above_base) != base) {
above_base = bdrv_cow_bs(above_base);
while (bdrv_filter_bs(above_base) != base) {
above_base = bdrv_filter_bs(above_base);
}
}
}

59
blockdev.c
View File

@ -2500,6 +2500,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
bool has_base, const char *base,
bool has_base_node, const char *base_node,
bool has_backing_file, const char *backing_file,
bool has_bottom, const char *bottom,
bool has_speed, int64_t speed,
bool has_on_error, BlockdevOnError on_error,
bool has_filter_node_name, const char *filter_node_name,
@ -2507,12 +2508,31 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
bool has_auto_dismiss, bool auto_dismiss,
Error **errp)
{
BlockDriverState *bs, *iter;
BlockDriverState *bs, *iter, *iter_end;
BlockDriverState *base_bs = NULL;
BlockDriverState *bottom_bs = NULL;
AioContext *aio_context;
Error *local_err = NULL;
int job_flags = JOB_DEFAULT;
if (has_base && has_base_node) {
error_setg(errp, "'base' and 'base-node' cannot be specified "
"at the same time");
return;
}
if (has_base && has_bottom) {
error_setg(errp, "'base' and 'bottom' cannot be specified "
"at the same time");
return;
}
if (has_bottom && has_base_node) {
error_setg(errp, "'bottom' and 'base-node' cannot be specified "
"at the same time");
return;
}
if (!has_on_error) {
on_error = BLOCKDEV_ON_ERROR_REPORT;
}
@ -2525,12 +2545,6 @@ 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 (has_base && has_base_node) {
error_setg(errp, "'base' and 'base-node' cannot be specified "
"at the same time");
goto out;
}
if (has_base) {
base_bs = bdrv_find_backing_image(bs, base);
if (base_bs == NULL) {
@ -2554,8 +2568,33 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
bdrv_refresh_filename(base_bs);
}
/* Check for op blockers in the whole chain between bs and base */
for (iter = bs; iter && iter != base_bs;
if (has_bottom) {
bottom_bs = bdrv_lookup_bs(NULL, bottom, errp);
if (!bottom_bs) {
goto out;
}
if (!bottom_bs->drv) {
error_setg(errp, "Node '%s' is not open", bottom);
goto out;
}
if (bottom_bs->drv->is_filter) {
error_setg(errp, "Node '%s' is a filter, use a non-filter node "
"as 'bottom'", bottom);
goto out;
}
if (!bdrv_chain_contains(bs, bottom_bs)) {
error_setg(errp, "Node '%s' is not in a chain starting from '%s'",
bottom, device);
goto out;
}
assert(bdrv_get_aio_context(bottom_bs) == aio_context);
}
/*
* Check for op blockers in the whole chain between bs and base (or bottom)
*/
iter_end = has_bottom ? bdrv_filter_or_cow_bs(bottom_bs) : base_bs;
for (iter = bs; iter && iter != iter_end;
iter = bdrv_filter_or_cow_bs(iter))
{
if (bdrv_op_is_blocked(iter, BLOCK_OP_TYPE_STREAM, errp)) {
@ -2579,7 +2618,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
}
stream_start(has_job_id ? job_id : NULL, bs, base_bs, backing_file,
job_flags, has_speed ? speed : 0, on_error,
bottom_bs, job_flags, has_speed ? speed : 0, on_error,
filter_node_name, &local_err);
if (local_err) {
error_propagate(errp, local_err);

1
include/block/block_int.h
View File

@ -1161,6 +1161,7 @@ int is_windows_drive(const char *filename);
*/
void stream_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *base, const char *backing_file_str,
BlockDriverState *bottom,
int creation_flags, int64_t speed,
BlockdevOnError on_error,
const char *filter_node_name,

12
qapi/block-core.json
View File

@ -2517,10 +2517,14 @@
# @device: the device or node name of the top image
#
# @base: the common backing file name.
# It cannot be set if @base-node is also set.
# It cannot be set if @base-node or @bottom is also set.
#
# @base-node: the node name of the backing file.
# It cannot be set if @base is also set. (Since 2.8)
# It cannot be set if @base or @bottom is also set. (Since 2.8)
#
# @bottom: the last node in the chain that should be streamed into
# top. It cannot be set if @base or @base-node is also set.
# It cannot be filter node. (Since 6.0)
#
# @backing-file: The backing file string to write into the top
# image. This filename is not validated.
@ -2576,8 +2580,8 @@
##
{ 'command': 'block-stream',
'data': { '*job-id': 'str', 'device': 'str', '*base': 'str',
'*base-node': 'str', '*backing-file': 'str', '*speed': 'int',
'*on-error': 'BlockdevOnError',
'*base-node': 'str', '*backing-file': 'str', '*bottom': 'str',
'*speed': 'int', '*on-error': 'BlockdevOnError',
'*filter-node-name': 'str',
'*auto-finalize': 'bool', '*auto-dismiss': 'bool' } }