This brings "incremental" mode to copy-before-write filter: user can specify bitmap so that filter will copy only "dirty" areas.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> --- qapi/block-core.json | 10 +++++++++- block/copy-before-write.c | 30 +++++++++++++++++++++++++++++- 2 files changed, 38 insertions(+), 2 deletions(-) diff --git a/qapi/block-core.json b/qapi/block-core.json index 6764d8b84f..c42d23752d 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -4063,11 +4063,19 @@ # # @target: The target for copy-before-write operations. # +# @bitmap: If specified, copy-before-write filter will do +# copy-before-write operations only for dirty regions of the +# bitmap. Bitmap size must be equal to length of file and +# target child of the filter. Note also, that bitmap is used +# only to initialize internal bitmap of the process, so further +# modifications (or removing) of specified bitmap doesn't +# influence the filter. +# # Since: 6.2 ## { 'struct': 'BlockdevOptionsCbw', 'base': 'BlockdevOptionsGenericFormat', - 'data': { 'target': 'BlockdevRef' } } + 'data': { 'target': 'BlockdevRef', '*bitmap': 'BlockDirtyBitmap' } } ## # @BlockdevOptions: diff --git a/block/copy-before-write.c b/block/copy-before-write.c index d31ca61111..e3456ad6aa 100644 --- a/block/copy-before-write.c +++ b/block/copy-before-write.c @@ -148,6 +148,7 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { BDRVCopyBeforeWriteState *s = bs->opaque; + BdrvDirtyBitmap *bitmap = NULL; bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds, BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, @@ -162,6 +163,33 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags, return -EINVAL; } + if (qdict_haskey(options, "bitmap.node") || + qdict_haskey(options, "bitmap.name")) + { + const char *bitmap_node, *bitmap_name; + + if (!qdict_haskey(options, "bitmap.node")) { + error_setg(errp, "bitmap.node is not specified"); + return -EINVAL; + } + + if (!qdict_haskey(options, "bitmap.name")) { + error_setg(errp, "bitmap.name is not specified"); + return -EINVAL; + } + + bitmap_node = qdict_get_str(options, "bitmap.node"); + bitmap_name = qdict_get_str(options, "bitmap.name"); + qdict_del(options, "bitmap.node"); + qdict_del(options, "bitmap.name"); + + bitmap = block_dirty_bitmap_lookup(bitmap_node, bitmap_name, NULL, + errp); + if (!bitmap) { + return -EINVAL; + } + } + bs->total_sectors = bs->file->bs->total_sectors; bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED | (BDRV_REQ_FUA & bs->file->bs->supported_write_flags); @@ -169,7 +197,7 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags, ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) & bs->file->bs->supported_zero_flags); - s->bcs = block_copy_state_new(bs->file, s->target, NULL, errp); + s->bcs = block_copy_state_new(bs->file, s->target, bitmap, errp); if (!s->bcs) { error_prepend(errp, "Cannot create block-copy-state: "); return -EINVAL; -- 2.29.2