Current scheme of image fleecing looks like this:
[guest] [NBD export]
| |
|root | root
v v
[copy-before-write] -----> [temp.qcow2]
| target |
|file |backing
v |
[active disk] <-------------+
- On guest writes copy-before-write filter copies old data from active
disk to temp.qcow2. So fleecing client (NBD export) when reads
changed regions from temp.qcow2 image and unchanged from active disk
through backing link.
This patch makes possible new image fleecing scheme:
[guest] [NBD export]
| |
| root | root
v file v
[copy-before-write]<------[snapshot-access]
| |
| file | target
v v
[active-disk] [temp.img]
- copy-before-write does CBW operations and also provides
snapshot-access API. The API may be accessed through
snapshot-access driver.
Benefits of new scheme:
1. Access control: if remote client try to read data that not covered
by original dirty bitmap used on copy-before-write open, client gets
-EACCES.
2. Discard support: if remote client do DISCARD, this additionally to
discarding data in temp.img informs block-copy process to not copy
these clusters. Next read from discarded area will return -EACCES.
This is significant thing: when fleecing user reads data that was
not yet copied to temp.img, we can avoid copying it on further guest
write.
3. Synchronisation between client reads and block-copy write is more
efficient. In old scheme we just rely on BDRV_REQ_SERIALISING flag
used for writes to temp.qcow2. New scheme is less blocking:
- fleecing reads are never blocked: if data region is untouched or
in-flight, we just read from active-disk, otherwise we read from
temp.img
- writes to temp.img are not blocked by fleecing reads
- still, guest writes of-course are blocked by in-flight fleecing
reads, that currently read from active-disk - it's the minimum
necessary blocking
4. Temporary image may be of any format, as we don't rely on backing
feature.
5. Permission relation are simplified. With old scheme we have to share
write permission on target child of copy-before-write, otherwise
backing link conflicts with copy-before-write file child write
permissions. With new scheme we don't have backing link, and
copy-before-write node may have unshared access to temporary node.
(Not realized in this commit, will be in future).
6. Having control on fleecing reads we'll be able to implement
alternative behavior on failed copy-before-write operations.
Currently we just break guest request (that's a historical behavior
of backup). But in some scenarios it's a bad behavior: better
is to drop the backup as failed but don't break guest request.
With new scheme we can simply unset some bits in a bitmap on CBW
failure and further fleecing reads will -EACCES, or something like
this. (Not implemented in this commit, will be in future)
Additional application for this is implementing timeout for CBW
operations.
Iotest 257 output is updated, as two more bitmaps now live in
copy-before-write filter.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20220303194349.2304213-13-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
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 <vsementsov@virtuozzo.com>
Message-Id: <20220303194349.2304213-5-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
This will be used in the following commit to bring "incremental" mode
to copy-before-write filter.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220303194349.2304213-4-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
We are going to complicate bitmap initialization in the further
commit. And in future, backup job will be able to work without filter
(when source is immutable), so we'll need same bitmap initialization in
copy-before-write filter and in backup job. So, it's reasonable to do
it in block-copy.
Note that for now cbw_open() is the only caller of
block_copy_state_new().
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220303194349.2304213-2-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
copy-before-write functions always run under BQL.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-24-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We are generally moving to int64_t for both offset and bytes parameters
on all io paths.
Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.
We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).
So, convert driver discard handlers bytes parameter to int64_t.
The only caller of all updated function is bdrv_co_pdiscard in
block/io.c. It is already prepared to work with 64bit requests, but
pass at most max(bs->bl.max_pdiscard, INT_MAX) to the driver.
Let's look at all updated functions:
blkdebug: all calculations are still OK, thanks to
bdrv_check_qiov_request().
both rule_check and bdrv_co_pdiscard are 64bit
blklogwrites: pass to blk_loc_writes_co_log which is 64bit
blkreplay, copy-on-read, filter-compress: pass to bdrv_co_pdiscard, OK
copy-before-write: pass to bdrv_co_pdiscard which is 64bit and to
cbw_do_copy_before_write which is 64bit
file-posix: one handler calls raw_account_discard() is 64bit and both
handlers calls raw_do_pdiscard(). Update raw_do_pdiscard, which pass
to RawPosixAIOData::aio_nbytes, which is 64bit (and calls
raw_account_discard())
gluster: somehow, third argument of glfs_discard_async is size_t.
Let's set max_pdiscard accordingly.
iscsi: iscsi_allocmap_set_invalid is 64bit,
!is_byte_request_lun_aligned is 64bit.
list.num is uint32_t. Let's clarify max_pdiscard and
pdiscard_alignment.
mirror_top: pass to bdrv_mirror_top_do_write() which is
64bit
nbd: protocol limitation. max_pdiscard is alredy set strict enough,
keep it as is for now.
nvme: buf.nlb is uint32_t and we do shift. So, add corresponding limits
to nvme_refresh_limits().
preallocate: pass to bdrv_co_pdiscard() which is 64bit.
rbd: pass to qemu_rbd_start_co() which is 64bit.
qcow2: calculations are still OK, thanks to bdrv_check_qiov_request(),
qcow2_cluster_discard() is 64bit.
raw-format: raw_adjust_offset() is 64bit, bdrv_co_pdiscard too.
throttle: pass to bdrv_co_pdiscard() which is 64bit and to
throttle_group_co_io_limits_intercept() which is 64bit as well.
test-block-iothread: bytes argument is unused
Great! Now all drivers are prepared to handle 64bit discard requests,
or else have explicit max_pdiscard limits.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-11-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We are generally moving to int64_t for both offset and bytes parameters
on all io paths.
Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.
We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).
So, convert driver write_zeroes handlers bytes parameter to int64_t.
The only caller of all updated function is bdrv_co_do_pwrite_zeroes().
bdrv_co_do_pwrite_zeroes() itself is of course OK with widening of
callee parameter type. Also, bdrv_co_do_pwrite_zeroes()'s
max_write_zeroes is limited to INT_MAX. So, updated functions all are
safe, they will not get "bytes" larger than before.
Still, let's look through all updated functions, and add assertions to
the ones which are actually unprepared to values larger than INT_MAX.
For these drivers also set explicit max_pwrite_zeroes limit.
Let's go:
blkdebug: calculations can't overflow, thanks to
bdrv_check_qiov_request() in generic layer. rule_check() and
bdrv_co_pwrite_zeroes() both have 64bit argument.
blklogwrites: pass to blk_log_writes_co_log() with 64bit argument.
blkreplay, copy-on-read, filter-compress: pass to
bdrv_co_pwrite_zeroes() which is OK
copy-before-write: Calls cbw_do_copy_before_write() and
bdrv_co_pwrite_zeroes, both have 64bit argument.
file-posix: both handler calls raw_do_pwrite_zeroes, which is updated.
In raw_do_pwrite_zeroes() calculations are OK due to
bdrv_check_qiov_request(), bytes go to RawPosixAIOData::aio_nbytes
which is uint64_t.
Check also where that uint64_t gets handed:
handle_aiocb_write_zeroes_block() passes a uint64_t[2] to
ioctl(BLKZEROOUT), handle_aiocb_write_zeroes() calls do_fallocate()
which takes off_t (and we compile to always have 64-bit off_t), as
does handle_aiocb_write_zeroes_unmap. All look safe.
gluster: bytes go to GlusterAIOCB::size which is int64_t and to
glfs_zerofill_async works with off_t.
iscsi: Aha, here we deal with iscsi_writesame16_task() that has
uint32_t num_blocks argument and iscsi_writesame16_task() has
uint16_t argument. Make comments, add assertions and clarify
max_pwrite_zeroes calculation.
iscsi_allocmap_() functions already has int64_t argument
is_byte_request_lun_aligned is simple to update, do it.
mirror_top: pass to bdrv_mirror_top_do_write which has uint64_t
argument
nbd: Aha, here we have protocol limitation, and NBDRequest::len is
uint32_t. max_pwrite_zeroes is cleanly set to 32bit value, so we are
OK for now.
nvme: Again, protocol limitation. And no inherent limit for
write-zeroes at all. But from code that calculates cdw12 it's obvious
that we do have limit and alignment. Let's clarify it. Also,
obviously the code is not prepared to handle bytes=0. Let's handle
this case too.
trace events already 64bit
preallocate: pass to handle_write() and bdrv_co_pwrite_zeroes(), both
64bit.
rbd: pass to qemu_rbd_start_co() which is 64bit.
qcow2: offset + bytes and alignment still works good (thanks to
bdrv_check_qiov_request()), so tail calculation is OK
qcow2_subcluster_zeroize() has 64bit argument, should be OK
trace events updated
qed: qed_co_request wants int nb_sectors. Also in code we have size_t
used for request length which may be 32bit. So, let's just keep
INT_MAX as a limit (aligning it down to pwrite_zeroes_alignment) and
don't care.
raw-format: Is OK. raw_adjust_offset and bdrv_co_pwrite_zeroes are both
64bit.
throttle: Both throttle_group_co_io_limits_intercept() and
bdrv_co_pwrite_zeroes() are 64bit.
vmdk: pass to vmdk_pwritev which is 64bit
quorum: pass to quorum_co_pwritev() which is 64bit
Hooray!
At this point all block drivers are prepared to support 64bit
write-zero requests, or have explicitly set max_pwrite_zeroes.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-8-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: use <= rather than < in assertions relying on max_pwrite_zeroes]
Signed-off-by: Eric Blake <eblake@redhat.com>
We are generally moving to int64_t for both offset and bytes parameters
on all io paths.
Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.
We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).
So, convert driver write handlers parameters which are already 64bit to
signed type.
While being here, convert also flags parameter to be BdrvRequestFlags.
Now let's consider all callers. Simple
git grep '\->bdrv_\(aio\|co\)_pwritev\(_part\)\?'
shows that's there three callers of driver function:
bdrv_driver_pwritev() and bdrv_driver_pwritev_compressed() in
block/io.c, both pass int64_t, checked by bdrv_check_qiov_request() to
be non-negative.
qcow2_save_vmstate() does bdrv_check_qiov_request().
Still, the functions may be called directly, not only by drv->...
Let's check:
git grep '\.bdrv_\(aio\|co\)_pwritev\(_part\)\?\s*=' | \
awk '{print $4}' | sed 's/,//' | sed 's/&//' | sort | uniq | \
while read func; do git grep "$func(" | \
grep -v "$func(BlockDriverState"; done
shows several callers:
qcow2:
qcow2_co_truncate() write at most up to @offset, which is checked in
generic qcow2_co_truncate() by bdrv_check_request().
qcow2_co_pwritev_compressed_task() pass the request (or part of the
request) that already went through normal write path, so it should
be OK
qcow:
qcow_co_pwritev_compressed() pass int64_t, it's updated by this patch
quorum:
quorum_co_pwrite_zeroes() pass int64_t and int - OK
throttle:
throttle_co_pwritev_compressed() pass int64_t, it's updated by this
patch
vmdk:
vmdk_co_pwritev_compressed() pass int64_t, it's updated by this
patch
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-5-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We are generally moving to int64_t for both offset and bytes parameters
on all io paths.
Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.
We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).
So, convert driver read handlers parameters which are already 64bit to
signed type.
While being here, convert also flags parameter to be BdrvRequestFlags.
Now let's consider all callers. Simple
git grep '\->bdrv_\(aio\|co\)_preadv\(_part\)\?'
shows that's there three callers of driver function:
bdrv_driver_preadv() in block/io.c, passes int64_t, checked by
bdrv_check_qiov_request() to be non-negative.
qcow2_load_vmstate() does bdrv_check_qiov_request().
do_perform_cow_read() has uint64_t argument. And a lot of things in
qcow2 driver are uint64_t, so converting it is big job. But we must
not work with requests that don't satisfy bdrv_check_qiov_request(),
so let's just assert it here.
Still, the functions may be called directly, not only by drv->...
Let's check:
git grep '\.bdrv_\(aio\|co\)_preadv\(_part\)\?\s*=' | \
awk '{print $4}' | sed 's/,//' | sed 's/&//' | sort | uniq | \
while read func; do git grep "$func(" | \
grep -v "$func(BlockDriverState"; done
The only one such caller:
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, &data, 1);
...
ret = bdrv_replace_test_co_preadv(bs, 0, 1, &qiov, 0);
in tests/unit/test-bdrv-drain.c, and it's OK obviously.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-4-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: fix typos]
Signed-off-by: Eric Blake <eblake@redhat.com>
The only caller pass copy_range and compress both false. Let's just
drop these arguments.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210824083856.17408-35-vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Finally, copy-before-write gets own .bdrv_open and .bdrv_close
handlers, block_init() call and becomes available through bdrv_open().
To achieve this:
- cbw_init gets unused flags argument and becomes cbw_open
- block_copy_state_free() call moved to new cbw_close()
- in bdrv_cbw_append:
- options are completed with driver and node-name, and we can simply
use bdrv_insert_node() to do both open and drained replacing
- in bdrv_cbw_drop:
- cbw_close() is now responsible for freeing s->bcs, so don't do it
here
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-22-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
We are going to publish copy-before-write filter to be used in separate
of backup. Future step would support bitmap for the filter. But let's
start from full set bitmap.
We have to modify backup, as bitmap is first initialized by
copy-before-write filter, and then backup modifies it.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-20-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
One more step closer to .bdrv_open(): use options instead of plain
arguments. Move to bdrv_open_child() calls, native for drive open
handlers.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824083856.17408-19-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824083856.17408-18-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
In the next commit we'll get rid of source argument of cbw_init().
Prepare to it now, to make next commit simpler: move the code block
that uses source below attaching the child and use bs->file->bs instead
of source variable.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-17-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
One more step closer to real .bdrv_open() handler: use more usual names
for bs being initialized and its state.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-16-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Move part of bdrv_cbw_append() to new function cbw_open(). It's an
intermediate step for adding normal .bdrv_open() handler to the
filter. With this commit no logic is changed, but we have a function
which will be turned into .bdrv_open() handler in future commit.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-15-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Refactor the function to replace child at last. Thus we don't need to
revert it and code is simplified.
block-copy state initialization being done before replacing the child
doesn't need any drained section.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-14-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
We are going to publish copy-before-write filter, and there no public
backing-child-based filter in Qemu. No reason to create a precedent, so
let's refactor copy-before-write filter instead.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-13-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
bdrv_attach_child() do bdrv_unref() on failure, so we shouldn't do it
by hand here.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-12-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
We are going to publish copy-before-write filter. So, user should be
able to create it with blockdev-add first, specifying both filtered and
target children. And then do blockdev-reopen, to actually insert the
filter where needed.
Currently, filter unshares write permission unconditionally on source
node. It's good, but it will not allow to do blockdev-add. So, let's
relax restrictions when filter doesn't have any parent.
Test output is modified, as now permission conflict happens only when
job creates a blk parent for filter node.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-11-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
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>
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>
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>
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>
