#include "blockstore.h" // Stabilize small write: // 1) Copy data from the journal to the data device // 2) Increase version on the metadata device and sync it // 3) Advance clean_db entry's version, clear previous journal entries // // This makes 1 4K small write+sync look like: // 512b+4K (journal) + sync + 512b (journal) + sync + 4K (data) [+ sync?] + 512b (metadata) + sync. // WA = 2.375. It's not the best, SSD FTL-like redirect-write could probably be lower // even with defragmentation. But it's fixed and it's still better than in Ceph. :) // except for HDD-only clusters, because each write results in 3 seeks. // Stabilize big write: // 1) Copy metadata from the journal to the metadata device // 2) Move dirty_db entry to clean_db and clear previous journal entries // // This makes 1 128K big write+sync look like: // 128K (data) + sync + 512b (journal) + sync + 512b (journal) + sync + 512b (metadata) + sync. // WA = 1.012. Very good :) // AND We must do it in batches, for the sake of reduced fsync call count // AND We must know what we stabilize. Basic workflow is like: // 1) primary OSD receives sync request // 2) it submits syncs to blockstore and peers // 3) after everyone acks sync it acks sync to the client // 4) after a while it takes his synced object list and sends stabilize requests // to peers and to its own blockstore, thus freeing the old version int blockstore::dequeue_stable(blockstore_operation *op) { obj_ver_id* v; int i, todo = 0; for (i = 0, v = (obj_ver_id*)op->buf; i < op->len; i++, v++) { auto dirty_it = dirty_db.find(*v); if (dirty_it == dirty_db.end()) { auto clean_it = clean_db.find(v->oid); if (clean_it == clean_db.end() || clean_it->second.version < v->version) { // No such object version op->retval = -EINVAL; op->callback(op); return 1; } else { // Already stable } } else if (IS_UNSYNCED(dirty_it->second.state)) { // Object not synced yet. Caller must sync it first op->retval = EAGAIN; op->callback(op); return 1; } else if (!IS_STABLE(dirty_it->second.state)) { todo++; } } if (!todo) { // Already stable op->retval = 0; op->callback(op); return 1; } // Check journal space blockstore_journal_check_t space_check(this); if (!space_check.check_available(op, todo, sizeof(journal_entry_stable), 0)) { return 0; } // There is sufficient space. Get SQEs struct io_uring_sqe *sqe[space_check.sectors_required]; for (i = 0; i < space_check.sectors_required; i++) { BS_SUBMIT_GET_SQE_DECL(sqe[i]); } // Prepare and submit journal entries auto cb = [this, op](ring_data_t *data) { handle_stable_event(data, op); }; int s = 0, cur_sector = -1; for (i = 0, v = (obj_ver_id*)op->buf; i < op->len; i++, v++) { auto unstab_it = unstable_writes.find(v->oid); if (unstab_it != unstable_writes.end() && unstab_it->second <= v->version) { unstable_writes.erase(unstab_it); } journal_entry_stable *je = (journal_entry_stable*) prefill_single_journal_entry(journal, JE_STABLE, sizeof(journal_entry_stable)); je->oid = v->oid; je->version = v->version; je->crc32 = je_crc32((journal_entry*)je); journal.crc32_last = je->crc32; if (cur_sector != journal.cur_sector) { if (cur_sector == -1) op->min_used_journal_sector = 1 + journal.cur_sector; cur_sector = journal.cur_sector; prepare_journal_sector_write(journal, sqe[s++], cb); } } op->max_used_journal_sector = 1 + journal.cur_sector; op->pending_ops = s; return 1; } void blockstore::handle_stable_event(ring_data_t *data, blockstore_operation *op) { if (data->res != data->iov.iov_len) { throw std::runtime_error( "write operation failed ("+std::to_string(data->res)+" != "+std::to_string(data->iov.iov_len)+ "). in-memory state is corrupted. AAAAAAAaaaaaaaaa!!!111" ); } op->pending_ops--; if (op->pending_ops == 0) { // Release used journal sectors if (op->min_used_journal_sector > 0) { uint64_t s = op->min_used_journal_sector; while (1) { journal.sector_info[s-1].usage_count--; if (s == op->max_used_journal_sector) break; s = 1 + s % journal.sector_count; } op->min_used_journal_sector = op->max_used_journal_sector = 0; } // First step: mark dirty_db entries as stable, acknowledge op completion obj_ver_id* v; int i; for (i = 0, v = (obj_ver_id*)op->buf; i < op->len; i++, v++) { // Mark all dirty_db entries up to op->version as stable auto dirty_it = dirty_db.find(*v); if (dirty_it != dirty_db.end()) { while (1) { if (dirty_it->second.state == ST_J_SYNCED) { dirty_it->second.state = ST_J_STABLE; } else if (dirty_it->second.state == ST_D_META_SYNCED) { dirty_it->second.state = ST_D_STABLE; } else if (IS_STABLE(dirty_it->second.state)) { break; } if (dirty_it == dirty_db.begin()) { break; } dirty_it--; if (dirty_it->first.oid != v->oid) { break; } } flusher->queue_flush(*v); } } // Acknowledge op op->retval = 0; op->callback(op); } }