[PATCH RFC v2 0/4] blockdev-replace
Hi all! v2: 1. Let's start with minimal functionality: replace only one specific child. 2. Explicit type of parent: qdev / export / driver Hmm, 'driver' is for BlockDriverState.. Any better idea? I don't want to call it "node" or even "block-node", as finally, devices and exports are kind of nodes too in the whole block graph.. 3. I think it's better to start with x- prefix Plans for v3: - add tests of filter insertion and removing - add qmp transaction support Vladimir Sementsov-Ogievskiy (4): block-backend: blk_root(): drop const specifier on return type block/export: add blk_by_export_id() block: make bdrv_find_child() function public qapi: add blockdev-replace command qapi/block.json | 61 ++++++++++++++++++++++++++++++++++ include/block/block_int.h | 1 + include/sysemu/block-backend.h | 3 +- block.c | 13 ++++++++ block/block-backend.c | 2 +- block/export/export.c | 18 ++++++++++ block/qapi-sysemu.c | 56 +++++++++++++++++++++++++++++++ blockdev.c | 14 -------- 8 files changed, 152 insertions(+), 16 deletions(-) -- 2.31.1
We'll need get non-const child pointer for graph modifications in further commits. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> --- include/sysemu/block-backend.h | 2 +- block/block-backend.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h index e5e1524f06..904d70f49c 100644 --- a/include/sysemu/block-backend.h +++ b/include/sysemu/block-backend.h @@ -277,7 +277,7 @@ int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in, int64_t bytes, BdrvRequestFlags read_flags, BdrvRequestFlags write_flags); -const BdrvChild *blk_root(BlockBackend *blk); +BdrvChild *blk_root(BlockBackend *blk); int blk_make_empty(BlockBackend *blk, Error **errp); diff --git a/block/block-backend.c b/block/block-backend.c index 12ef80ea17..d994a0f096 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -2438,7 +2438,7 @@ int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in, bytes, read_flags, write_flags); } -const BdrvChild *blk_root(BlockBackend *blk) +BdrvChild *blk_root(BlockBackend *blk) { return blk->root; } -- 2.31.1
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> --- include/sysemu/block-backend.h | 1 + block/export/export.c | 18 ++++++++++++++++++ 2 files changed, 19 insertions(+) diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h index 904d70f49c..250c7465a5 100644 --- a/include/sysemu/block-backend.h +++ b/include/sysemu/block-backend.h @@ -124,6 +124,7 @@ DeviceState *blk_get_attached_dev(BlockBackend *blk); char *blk_get_attached_dev_id(BlockBackend *blk); BlockBackend *blk_by_dev(void *dev); BlockBackend *blk_by_qdev_id(const char *id, Error **errp); +BlockBackend *blk_by_export_id(const char *id, Error **errp); void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque); int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset, int64_t bytes, QEMUIOVector *qiov, diff --git a/block/export/export.c b/block/export/export.c index 6d3b9964c8..613b5bc1d5 100644 --- a/block/export/export.c +++ b/block/export/export.c @@ -362,3 +362,21 @@ BlockExportInfoList *qmp_query_block_exports(Error **errp) return head; } + +BlockBackend *blk_by_export_id(const char *id, Error **errp) +{ + BlockExport *exp; + + exp = blk_exp_find(id); + if (exp == NULL) { + error_setg(errp, "Export '%s' not found", id); + return NULL; + } + + if (!exp->blk) { + error_setg(errp, "Export '%s' is empty", id); + return NULL; + } + + return exp->blk; +} -- 2.31.1
To be reused soon. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> --- include/block/block_int.h | 1 + block.c | 13 +++++++++++++ blockdev.c | 14 -------------- 3 files changed, 14 insertions(+), 14 deletions(-) diff --git a/include/block/block_int.h b/include/block/block_int.h index f4c75e8ba9..79bdde8bf4 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -1433,6 +1433,7 @@ BdrvDirtyBitmap *block_dirty_bitmap_remove(const char *node, const char *name, BlockDriverState **bitmap_bs, Error **errp); +BdrvChild *bdrv_find_child(BlockDriverState *parent_bs, const char *child_name); BdrvChild *bdrv_cow_child(BlockDriverState *bs); BdrvChild *bdrv_filter_child(BlockDriverState *bs); BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs); diff --git a/block.c b/block.c index 0ac5b163d2..840d52e7c8 100644 --- a/block.c +++ b/block.c @@ -7727,6 +7727,19 @@ int bdrv_make_empty(BdrvChild *c, Error **errp) return 0; } +BdrvChild *bdrv_find_child(BlockDriverState *parent_bs, const char *child_name) +{ + BdrvChild *child; + + QLIST_FOREACH(child, &parent_bs->children, next) { + if (strcmp(child->name, child_name) == 0) { + return child; + } + } + + return NULL; +} + /* * Return the child that @bs acts as an overlay for, and from which data may be * copied in COW or COR operations. Usually this is the backing file. diff --git a/blockdev.c b/blockdev.c index 0eb2823b1b..ce23059d5e 100644 --- a/blockdev.c +++ b/blockdev.c @@ -3644,20 +3644,6 @@ out: aio_context_release(aio_context); } -static BdrvChild *bdrv_find_child(BlockDriverState *parent_bs, - const char *child_name) -{ - BdrvChild *child; - - QLIST_FOREACH(child, &parent_bs->children, next) { - if (strcmp(child->name, child_name) == 0) { - return child; - } - } - - return NULL; -} - void qmp_x_blockdev_change(const char *parent, bool has_child, const char *child, bool has_node, const char *node, Error **errp) -- 2.31.1
Add a command that can replace bs in following BdrvChild structures: - qdev blk root child - block-export blk root child - any child BlockDriverState selected by child-name Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> --- qapi/block.json | 61 +++++++++++++++++++++++++++++++++++++++++++++ block/qapi-sysemu.c | 56 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 117 insertions(+) diff --git a/qapi/block.json b/qapi/block.json index 82fcf2c914..a4dd1e34d4 100644 --- a/qapi/block.json +++ b/qapi/block.json @@ -570,3 +570,64 @@ '*boundaries-read': ['uint64'], '*boundaries-write': ['uint64'], '*boundaries-flush': ['uint64'] } } +## +# @BlockParentType: +# +# Since 7.0 +## +{ 'enum': 'BlockParentType', + 'data': ['qdev', 'driver', 'export'] } + +## +# @BdrvChildRefQdev: +# +# Since 7.0 +## +{ 'struct': 'BdrvChildRefQdev', + 'data': { 'qdev-id': 'str' } } + +## +# @BdrvChildRefExport: +# +# Since 7.0 +## +{ 'struct': 'BdrvChildRefExport', + 'data': { 'export-id': 'str' } } + +## +# @BdrvChildRefDriver: +# +# Since 7.0 +## +{ 'struct': 'BdrvChildRefDriver', + 'data': { 'node-name': 'str', 'child': 'str' } } + +## +# @BlockdevReplace: +# +# Since 7.0 +## +{ 'union': 'BlockdevReplace', + 'base': { + 'parent-type': 'BlockParentType', + 'new-child': 'str' + }, + 'discriminator': 'parent-type', + 'data': { + 'qdev': 'BdrvChildRefQdev', + 'export': 'BdrvChildRefExport', + 'driver': 'BdrvChildRefDriver' + } } + +## +# @x-blockdev-replace: +# +# Replace a block-node associated with device (selected by +# @qdev-id) or with block-export (selected by @export-id) or +# any child of block-node (selected by @node-name and @child) +# with @new-child block-node. +# +# Since 7.0 +## +{ 'command': 'x-blockdev-replace', 'boxed': true, + 'data': 'BlockdevReplace' } diff --git a/block/qapi-sysemu.c b/block/qapi-sysemu.c index 8498402ad4..ca1aaef376 100644 --- a/block/qapi-sysemu.c +++ b/block/qapi-sysemu.c @@ -588,3 +588,59 @@ void qmp_block_latency_histogram_set( } } } + +void qmp_x_blockdev_replace(BlockdevReplace *repl, Error **errp) +{ + BdrvChild *child = NULL; + BlockDriverState *new_child_bs; + + if (repl->parent_type == BLOCK_PARENT_TYPE_DRIVER) { + BlockDriverState *parent_bs; + + parent_bs = bdrv_find_node(repl->u.driver.node_name); + if (!parent_bs) { + error_setg(errp, "Block driver node with node-name '%s' not " + "found", repl->u.driver.node_name); + return; + } + + child = bdrv_find_child(parent_bs, repl->u.driver.child); + if (!child) { + error_setg(errp, "Block driver node '%s' doesn't have child " + "named '%s'", repl->u.driver.node_name, + repl->u.driver.child); + return; + } + } else { + /* Other types are similar, they work through blk */ + BlockBackend *blk; + bool is_qdev = repl->parent_type == BLOCK_PARENT_TYPE_QDEV; + const char *id = + is_qdev ? repl->u.qdev.qdev_id : repl->u.export.export_id; + + assert(is_qdev || repl->parent_type == BLOCK_PARENT_TYPE_EXPORT); + + blk = is_qdev ? blk_by_qdev_id(id, errp) : blk_by_export_id(id, errp); + if (!blk) { + return; + } + + child = blk_root(blk); + if (!child) { + error_setg(errp, "%s '%s' is empty, nothing to replace", + is_qdev ? "Device" : "Export", id); + return; + } + } + + assert(child); + assert(child->bs); + + new_child_bs = bdrv_find_node(repl->new_child); + if (!new_child_bs) { + error_setg(errp, "Node '%s' not found", repl->new_child); + return; + } + + bdrv_replace_child_bs(child, new_child_bs, errp); +} -- 2.31.1
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Vladimir Sementsov-Ogievskiy