14.06.2021 10:33, Emanuele Giuseppe Esposito wrote:
From: Paolo Bonzini <pbonz...@redhat.com>
Put the logic to determine the copy size in a separate function, so
that there is a simple state machine for the possible methods of
copying data from one BlockDriverState to the other.
Use .method instead of .copy_range as in-out argument, and
include also .zeroes as an additional copy method.
While at it, store the common computation of block_copy_max_transfer
into a new field of BlockCopyState, and make sure that we always
obey max_transfer; that's more efficient even for the
COPY_RANGE_READ_WRITE case.
Signed-off-by: Emanuele Giuseppe Esposito <eespo...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
block/block-copy.c | 174 +++++++++++++++++++++++----------------------
1 file changed, 89 insertions(+), 85 deletions(-)
[..]
@@ -267,28 +293,28 @@ BlockCopyState *block_copy_state_new(BdrvChild *source,
BdrvChild *target,
.len = bdrv_dirty_bitmap_size(copy_bitmap),
.write_flags = write_flags,
.mem = shres_create(BLOCK_COPY_MAX_MEM),
+ .max_transfer = QEMU_ALIGN_DOWN(
+ block_copy_max_transfer(source, target),
+ cluster_size),
};
- if (block_copy_max_transfer(source, target) < cluster_size) {
+ if (s->max_transfer < cluster_size) {
/*
* copy_range does not respect max_transfer. We don't want to bother
* with requests smaller than block-copy cluster size, so fallback to
* buffered copying (read and write respect max_transfer on their
* behalf).
*/
- s->use_copy_range = false;
- s->copy_size = cluster_size;
+ s->method = COPY_READ_WRITE_CLUSTER;
} else if (write_flags & BDRV_REQ_WRITE_COMPRESSED) {
/* Compression supports only cluster-size writes and no copy-range. */
- s->use_copy_range = false;
- s->copy_size = cluster_size;
+ s->method = COPY_READ_WRITE_CLUSTER;
} else {
/*
* We enable copy-range, but keep small copy_size, until first
* successful copy_range (look at block_copy_do_copy).
*/
Comment outdated. Maybe:
/* if copy range enabled, start with COPY_RANGE_SMALL, until first successful
copy_range (look at block_copy_do_copy). */
- s->use_copy_range = use_copy_range;
- s->copy_size = MAX(s->cluster_size, BLOCK_COPY_MAX_BUFFER);
+ s->method = use_copy_range ? COPY_RANGE_SMALL : COPY_READ_WRITE;
}
ratelimit_init(&s->rate_limit);
[..]
@@ -377,76 +400,59 @@ static int coroutine_fn block_copy_do_copy(BlockCopyState
*s,
*error_is_read = false;
}
return ret;
- }
- if (*copy_range) {
+ case COPY_RANGE_SMALL:
+ case COPY_RANGE_FULL:
ret = bdrv_co_copy_range(s->source, offset, s->target, offset, nbytes,
0, s->write_flags);
- if (ret < 0) {
- trace_block_copy_copy_range_fail(s, offset, ret);
- *copy_range = false;
- /* Fallback to read+write with allocated buffer */
- } else {
+ if (ret >= 0) {
+ /* Successful copy-range, increase copy_size. */
No copy_size now. So, "increase chunk size".
+ *method = COPY_RANGE_FULL;
return 0;
}
- }
Comment tweaks are non-critical, can be done in-flight.
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
--
Best regards,
Vladimir
