14.11.2019 14:27, Max Reitz wrote: > On 13.11.19 19:43, Andrey Shinkevich wrote: >> Allow writing all the data compressed through the filter driver. >> The written data will be aligned by the cluster size. >> Based on the QEMU current implementation, that data can be written to >> unallocated clusters only. May be used for a backup job. >> >> Suggested-by: Max Reitz <mre...@redhat.com> >> Signed-off-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com> >> --- >> block/Makefile.objs | 1 + >> block/filter-compress.c | 201 >> ++++++++++++++++++++++++++++++++++++++++++++++++ >> qapi/block-core.json | 10 ++- >> 3 files changed, 208 insertions(+), 4 deletions(-) >> create mode 100644 block/filter-compress.c >> >> diff --git a/block/Makefile.objs b/block/Makefile.objs >> index e394fe0..330529b 100644 >> --- a/block/Makefile.objs >> +++ b/block/Makefile.objs >> @@ -43,6 +43,7 @@ block-obj-y += crypto.o >> >> block-obj-y += aio_task.o >> block-obj-y += backup-top.o >> +block-obj-y += filter-compress.o >> >> common-obj-y += stream.o >> >> diff --git a/block/filter-compress.c b/block/filter-compress.c >> new file mode 100644 >> index 0000000..64b1ee5 >> --- /dev/null >> +++ b/block/filter-compress.c >> @@ -0,0 +1,201 @@ >> +/* >> + * Compress filter block driver >> + * >> + * Copyright (c) 2019 Virtuozzo International GmbH >> + * >> + * Author: >> + * Andrey Shinkevich <andrey.shinkev...@virtuozzo.com> >> + * (based on block/copy-on-read.c by Max Reitz) >> + * >> + * This program is free software; you can redistribute it and/or >> + * modify it under the terms of the GNU General Public License as >> + * published by the Free Software Foundation; either version 2 or >> + * (at your option) any later version of the License. >> + * >> + * This program is distributed in the hope that it will be useful, >> + * but WITHOUT ANY WARRANTY; without even the implied warranty of >> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >> + * GNU General Public License for more details. >> + * >> + * You should have received a copy of the GNU General Public License >> + * along with this program; if not, see <http://www.gnu.org/licenses/>. >> + */ >> + >> +#include "qemu/osdep.h" >> +#include "block/block_int.h" >> +#include "qemu/module.h" >> + >> + >> +static int compress_open(BlockDriverState *bs, QDict *options, int flags, >> + Error **errp) >> +{ >> + bs->backing = bdrv_open_child(NULL, options, "file", bs, &child_file, >> false, >> + errp); > > Please don’t attach something that the QAPI schema calls “file” as > bs->backing.
Agree, it's a mistake. If we want backing and user set backing in options, it's opened automatically, I think.. > > Yes, attaching it as bs->file would break backing chains. That’s a bug > in the block layer. I’ve been working on a fix for a long time. > > Please don’t introduce more weirdness just because we have a bug in the > block layer. > > (Note that I’d strongly oppose calling the child “backing” in the QAPI > schema, as this would go against what all other user-creatable filters do.) > So, are you opposite to correct backing-based user-creatable filter (with backing both in QAPI and code)? Do you think, that if we make backup-top to be user-creatable, we should move it to be file-child-based, or support both backing and file child? -- Best regards, Vladimir
