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Fsync & update metadata when block checksums are enabled

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This commit is contained in:
Vitaliy Filippov
2025-11-23 19:08:23 +03:00
parent 18a2858c62
commit bff3d35c85
4 changed files with 56 additions and 71 deletions
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src/blockstore/blockstore_flush.cpp
+52 -57
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@@ -18,7 +18,6 @@ journal_flusher_t::journal_flusher_t(blockstore_impl_t *bs)
this->cur_flusher_count = bs->min_flusher_count;
this->target_flusher_count = bs->min_flusher_count;
active_flushers = 0;
syncing_flushers = 0;
advance_lsn_counter = 0;
co = new journal_flusher_co[max_flusher_count];
for (int i = 0; i < max_flusher_count; i++)
@@ -169,6 +168,8 @@ bool journal_flusher_co::loop()
else if (wait_state == 21) goto resume_21;
else if (wait_state == 22) goto resume_22;
else if (wait_state == 23) goto resume_23;
else if (wait_state == 24) goto resume_24;
else if (wait_state == 25) goto resume_25;
resume_0:
wait_state = 0;
cur_oid = {};
@@ -252,6 +253,10 @@ resume_1:
{
// Read original checksum blocks to calculate padded checksums if required
fill_partial_checksum_blocks();
if (read_to_fill_incomplete)
{
flusher->wanting_meta_fsync++;
}
}
// Read buffered data
cur_obj = NULL;
@@ -259,25 +264,35 @@ resume_1:
resume_2:
resume_3:
if (!read_buffered(2))
{
return false;
}
// Now, if csum_block_size is > bitmap_granularity and if we are doing partial checksum block updates,
// perform a trick: clear bitmap bits in the metadata entry and recalculate block checksum with zeros
// in place of overwritten parts. Then, even if the actual partial update fully or partially fails,
// we'll have a correct checksum because it won't include overwritten parts!
// The same thing actually happens even when csum_block_size == bitmap_granularity, but in that case
// we never need to read (and thus verify) overwritten parts from the data device.
if (read_to_fill_incomplete)
{
flusher->wanting_meta_fsync--;
}
res = check_and_punch_checksums();
if (res == EBUSY)
{
resume_4:
resume_5:
if (!write_meta_block(4))
{
return false;
}
resume_6:
resume_7:
resume_8:
if (!fsync_batch(true, 6)) // FIXME: is it correct to batch here
if (!fsync_meta(6))
{
return false;
}
}
else if (res == ENOENT || res == EDOM)
{
@@ -311,13 +326,22 @@ resume_10:
// Mark the object compacted, but don't free and remove small_writes
// We'll free and remove them only when trimming
// The only thing we modify here are big_write block checksums if >4k block is used
cur_obj = bs->heap->read_entry(cur_oid, NULL);
cur_obj = bs->heap->read_entry(cur_oid, &modified_block);
if (!cur_obj)
{
// Abort compaction
goto release_oid;
}
calc_block_checksums();
if (read_to_fill_incomplete)
{
resume_24:
resume_25:
if (!write_meta_block(24))
{
return false;
}
}
bs->heap->mark_object_compacted(cur_obj, compact_lsn);
// Done, free all buffers
free_buffers();
@@ -635,66 +659,37 @@ resume_1:
return true;
}
bool journal_flusher_co::fsync_batch(bool fsync_meta, int wait_base)
bool journal_flusher_co::fsync_meta(int wait_base)
{
if (wait_state == wait_base) goto resume_0;
else if (wait_state == wait_base+1) goto resume_1;
else if (wait_state == wait_base+2) goto resume_2;
if (!(fsync_meta ? bs->dsk.disable_meta_fsync : bs->dsk.disable_data_fsync))
resume_0:
if (bs->dsk.disable_meta_fsync)
{
cur_sync = flusher->syncs.end();
while (cur_sync != flusher->syncs.begin())
{
cur_sync--;
if (cur_sync->fsync_meta == fsync_meta && cur_sync->state == 0)
{
goto sync_found;
}
}
cur_sync = flusher->syncs.emplace(flusher->syncs.end(), (flusher_sync_t){
.fsync_meta = fsync_meta,
.ready_count = 0,
.state = 0,
});
sync_found:
cur_sync->ready_count++;
flusher->syncing_flushers++;
resume_1:
if (!cur_sync->state)
{
if (flusher->syncing_flushers >= flusher->active_flushers || true /*FIXME*/)
{
// Sync batch is ready. Do it.
await_sqe(0);
data->iov = { 0 };
data->callback = simple_callback_w;
io_uring_prep_fsync(sqe, fsync_meta ? bs->dsk.meta_fd : bs->dsk.data_fd, IORING_FSYNC_DATASYNC);
cur_sync->state = 1;
wait_count++;
resume_2:
if (wait_count > 0)
{
wait_state = wait_base+2;
return false;
}
// Sync completed. All previous coroutines waiting for it must be resumed
cur_sync->state = 2;
bs->ringloop->wakeup();
}
else
{
// Wait until someone else sends and completes a sync.
wait_state = wait_base+1;
return false;
}
}
flusher->syncing_flushers--;
cur_sync->ready_count--;
if (cur_sync->ready_count == 0)
{
flusher->syncs.erase(cur_sync);
}
return true;
}
if (flusher->wanting_meta_fsync || flusher->fsyncing_meta > 0)
{
wait_state = wait_base;
return false;
}
flusher->fsyncing_meta = true;
// Sync batch is ready. Do it.
await_sqe(1);
data->iov = { 0 };
data->callback = simple_callback_w;
io_uring_prep_fsync(sqe, bs->dsk.meta_fd, IORING_FSYNC_DATASYNC);
wait_count++;
resume_2:
if (wait_count > 0)
{
wait_state = wait_base+2;
return false;
}
// Sync completed. All previous coroutines waiting for it must be resumed
flusher->fsyncing_meta = false;
bs->ringloop->wakeup();
return true;
}