block/backup: move cluster size calculation to block-copy

The main consumer of cluster-size is block-copy. Let's calculate it
here instead of passing through backup-top.

We are going to publish cop

block/backup: move cluster size calculation to block-copy

The main consumer of cluster-size is block-copy. Let's calculate it
here instead of passing through backup-top.

We are going to publish copy-before-write filter soon, so it will be
created through options. But we don't want for now to make explicit
option for cluster-size, let's continue to calculate it automatically.
So, now is the time to get rid of cluster_size argument for
bdrv_cbw_append().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-10-vsementsov@virtuozzo.com>
[hreitz: Add qemu/error-report.h include to block/block-copy.c]
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

show more ...

block/backup: set copy_range and compress after filter insertion

We are going to publish copy-before-write filter, so it would be
initialized through options. Still we don't want to publish compress

block/backup: set copy_range and compress after filter insertion

We are going to publish copy-before-write filter, so it would be
initialized through options. Still we don't want to publish compress
and copy-range options, as

1. Modern way to enable compression is to use compress filter.

2. For copy-range it's unclean how to make proper interface:
- it's has experimental prefix for backup job anyway
- the whole BackupPerf structure doesn't make sense for the filter
So, let's just add copy-range possibility to the filter later if
needed.

Still, we are going to continue support for compression and
experimental copy-range in backup job. So, set these options after
filter creation.

Note, that we can drop "compress" argument of bdrv_cbw_append() now, as
well as "perf". The only reason not doing so is that now, when I
prepare this patch the big series around it is already reviewed and I
want to avoid extra rebase conflicts to simplify review of the
following version.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824083856.17408-9-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

show more ...

block-copy: move detecting fleecing scheme to block-copy

We want to simplify initialization interface of copy-before-write
filter as we are going to make it public. So, let's detect fleecing
scheme

block-copy: move detecting fleecing scheme to block-copy

We want to simplify initialization interface of copy-before-write
filter as we are going to make it public. So, let's detect fleecing
scheme exactly in block-copy code, to not pass this information through
extra levels.

Why not just set BDRV_REQ_SERIALISING unconditionally: because we are
going to implement new more efficient fleecing scheme which will not
rely on backing feature.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824083856.17408-7-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

show more ...

block: rename backup-top to copy-before-write

We are going to convert backup_top to full featured public filter,
which can be used in separate of backup job. Start from renaming from
"how it used" t

block: rename backup-top to copy-before-write

We are going to convert backup_top to full featured public filter,
which can be used in separate of backup job. Start from renaming from
"how it used" to "what it does".

While updating comments in 283 iotest, drop and rephrase also things
about ".active", as this field is now dropped, and filter doesn't have
"inactive" mode.

Note that this change may be considered as incompatible interface
change, as backup-top filter format name was visible through
query-block and query-named-block-nodes.

Still, consider the following reasoning:

1. backup-top was never documented, so if someone depends on format
name (for driver that can't be used other than it is automatically
inserted on backup job start), it's a kind of "undocumented feature
use". So I think we are free to change it.

2. There is a hope, that there is no such users: it's a lot more native
to give a good node-name to backup-top filter if need to operate
with it somehow, and don't touch format name.

3. Another "incompatible" change in further commit would be moving
copy-before-write filter from using backing child to file child. And
this is even more reasonable than renaming: for now all public
filters are file-child based.

So, it's a risky change, but risk seems small and good interface worth
it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-6-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

show more ...