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Track used blocks, not object versions

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This commit is contained in:
Vitaliy Filippov
2023-07-17 00:34:58 +03:00
parent 3c565e7b94
commit e4ea8a9514
4 changed files with 31 additions and 67 deletions
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src/blockstore_read.cpp
+16 -48
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@@ -131,7 +131,7 @@ int blockstore_impl_t::fulfill_read(blockstore_op_t *read_op,
// If we don't track it then we may IN THEORY read another object's data:
// submit read -> remove the object -> flush remove -> overwrite with another object -> finish read
// Very improbable, but possible
PRIV(read_op)->clean_version_used = 1;
PRIV(read_op)->clean_block_used = 1;
}
rv.insert(rv.begin() + pos, el);
fulfilled += el.len;
@@ -371,14 +371,9 @@ bool blockstore_impl_t::read_checksum_block(blockstore_op_t *op, int rv_pos, uin
}
if (!(vi->copy_flags & COPY_BUF_JOURNAL))
{
// Reading may race with flushing.
// - Flushing happens in 3 steps: (2) punch holes in meta -> (4) update data -> (6) update meta
// - Reading may start/end at: 1/3, 1/5, 1/7, 3/5, 3/7, 5/7
// - 1/3, 1/5, 3/5 are not a problem because we'll check data using punched bitmap and CRCs
// - For 1/7, 3/7 and 5/7 to finish correctly we need a copy of punched metadata
// otherwise the checksum may not match
// So flushers save a copy of punched metadata if the object is being read during (6).
PRIV(op)->clean_version_used = 1;
// Reads running parallel to flushes of the same clean block may read
// a mixture of old and new data. So we don't verify checksums for such blocks.
PRIV(op)->clean_block_used = 1;
}
return true;
}
@@ -404,7 +399,7 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *read_op)
}
uint64_t fulfilled = 0;
PRIV(read_op)->pending_ops = 0;
PRIV(read_op)->clean_version_used = 0;
PRIV(read_op)->clean_block_used = 0;
auto & rv = PRIV(read_op)->read_vec;
uint64_t result_version = 0;
if (dirty_found)
@@ -617,7 +612,7 @@ bool blockstore_impl_t::fulfill_clean_read(blockstore_op_t *read_op, uint64_t &
return false;
}
}
PRIV(read_op)->clean_version_used = req > 0;
PRIV(read_op)->clean_block_used = req > 0;
}
else if (from_journal)
{
@@ -682,14 +677,13 @@ bool blockstore_impl_t::fulfill_clean_read(blockstore_op_t *read_op, uint64_t &
}
}
// Increment reference counter if clean data is being read from the disk
if (PRIV(read_op)->clean_version_used)
if (PRIV(read_op)->clean_block_used)
{
obj_ver_id ov = { .oid = read_op->oid, .version = clean_ver };
auto & uo = used_clean_objects[ov];
auto & uo = used_clean_objects[clean_loc];
uo.refs++;
if (dsk.csum_block_size && flusher->is_flushed_over(ov))
if (dsk.csum_block_size && flusher->is_mutated(clean_loc))
uo.was_changed = true;
PRIV(read_op)->clean_version_used = ov.version;
PRIV(read_op)->clean_block_used = clean_loc;
}
return true;
}
@@ -872,7 +866,7 @@ void blockstore_impl_t::handle_read_event(ring_data_t *data, blockstore_op_t *op
{
// BIG_WRITE from journal or clean data
// Do not verify checksums if the data location is/was mutated by flushers
auto & uo = used_clean_objects.at((obj_ver_id){ .oid = op->oid, .version = PRIV(op)->clean_version_used });
auto & uo = used_clean_objects.at((rv[i].disk_offset >> dsk.block_order) << dsk.block_order);
if (!uo.was_changed)
{
verify_clean_padded_checksums(
@@ -948,46 +942,20 @@ void blockstore_impl_t::handle_read_event(ring_data_t *data, blockstore_op_t *op
meta_block = NULL;
}
}
if (PRIV(op)->clean_version_used)
if (PRIV(op)->clean_block_used)
{
// Release clean data block
obj_ver_id ov = { .oid = op->oid, .version = PRIV(op)->clean_version_used };
auto uo_it = used_clean_objects.find(ov);
auto uo_it = used_clean_objects.find(PRIV(op)->clean_block_used);
if (uo_it != used_clean_objects.end())
{
uo_it->second.refs--;
if (uo_it->second.refs <= 0)
{
// Check to the left - even older usage entries may exist
bool still_used = false;
while (uo_it != used_clean_objects.begin())
if (uo_it->second.was_freed)
{
uo_it--;
if (uo_it->first.oid != op->oid)
{
uo_it++;
break;
}
if (uo_it->second.refs > 0)
{
still_used = true;
break;
}
}
// Free uo_it AND all following records with refs==0 too
if (!still_used)
{
while (uo_it != used_clean_objects.end() &&
uo_it->first.oid == op->oid &&
uo_it->second.refs == 0)
{
if (uo_it->second.freed_block > 0)
{
data_alloc->set(uo_it->second.freed_block-1, false);
}
used_clean_objects.erase(uo_it++);
}
data_alloc->set(PRIV(op)->clean_block_used, false);
}
used_clean_objects.erase(uo_it);
}
}
}