Vitaliy Filippov
4a2dcf7b6b
VNPL 1.1 is slightly reworded to make it clear that proprietary software interacting with Vitastor and providing some kind of service to end users isn't a "Proxy Program" if it's not specially designed to be used with Vitastor. For example, Windows OS running in a virtual machine stored in a Vitastor cluster clearly isn't.
237 lines
7.8 KiB
C++
237 lines
7.8 KiB
C++
// Copyright (c) Vitaliy Filippov, 2019+
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// License: VNPL-1.1 (see README.md for details)
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#include "blockstore_impl.h"
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// Stabilize small write:
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// 1) Copy data from the journal to the data device
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// 2) Increase version on the metadata device and sync it
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// 3) Advance clean_db entry's version, clear previous journal entries
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//
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// This makes 1 4K small write+sync look like:
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// 512b+4K (journal) + sync + 512b (journal) + sync + 4K (data) [+ sync?] + 512b (metadata) + sync.
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// WA = 2.375. It's not the best, SSD FTL-like redirect-write could probably be lower
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// even with defragmentation. But it's fixed and it's still better than in Ceph. :)
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// except for HDD-only clusters, because each write results in 3 seeks.
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// Stabilize big write:
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// 1) Copy metadata from the journal to the metadata device
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// 2) Move dirty_db entry to clean_db and clear previous journal entries
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//
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// This makes 1 128K big write+sync look like:
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// 128K (data) + sync + 512b (journal) + sync + 512b (journal) + sync + 512b (metadata) + sync.
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// WA = 1.012. Very good :)
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// Stabilize delete:
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// 1) Remove metadata entry and sync it
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// 2) Remove dirty_db entry and clear previous journal entries
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// We have 2 problems here:
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// - In the cluster environment, we must store the "tombstones" of deleted objects until
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// all replicas (not just quorum) agrees about their deletion. That is, "stabilize" is
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// not possible for deletes in degraded placement groups
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// - With simple "fixed" metadata tables we can't just clear the metadata entry of the latest
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// object version. We must clear all previous entries, too.
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// FIXME Fix both problems - probably, by switching from "fixed" metadata tables to "dynamic"
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// AND We must do it in batches, for the sake of reduced fsync call count
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// AND We must know what we stabilize. Basic workflow is like:
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// 1) primary OSD receives sync request
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// 2) it submits syncs to blockstore and peers
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// 3) after everyone acks sync it acks sync to the client
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// 4) after a while it takes his synced object list and sends stabilize requests
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// to peers and to its own blockstore, thus freeing the old version
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int blockstore_impl_t::dequeue_stable(blockstore_op_t *op)
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{
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if (PRIV(op)->op_state)
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{
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return continue_stable(op);
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}
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obj_ver_id* v;
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int i, todo = 0;
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for (i = 0, v = (obj_ver_id*)op->buf; i < op->len; i++, v++)
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{
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auto dirty_it = dirty_db.find(*v);
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if (dirty_it == dirty_db.end())
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{
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auto clean_it = clean_db.find(v->oid);
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if (clean_it == clean_db.end() || clean_it->second.version < v->version)
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{
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// No such object version
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op->retval = -ENOENT;
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FINISH_OP(op);
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return 1;
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}
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else
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{
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// Already stable
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}
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}
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else if (IS_IN_FLIGHT(dirty_it->second.state))
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{
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// Object write is still in progress. Wait until the write request completes
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return 0;
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}
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else if (!IS_SYNCED(dirty_it->second.state))
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{
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// Object not synced yet. Caller must sync it first
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op->retval = -EBUSY;
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FINISH_OP(op);
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return 1;
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}
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else if (!IS_STABLE(dirty_it->second.state))
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{
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todo++;
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}
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}
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if (!todo)
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{
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// Already stable
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op->retval = 0;
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FINISH_OP(op);
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return 1;
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}
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// Check journal space
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blockstore_journal_check_t space_check(this);
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if (!space_check.check_available(op, todo, sizeof(journal_entry_stable), 0))
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{
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return 0;
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}
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// There is sufficient space. Get SQEs
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struct io_uring_sqe *sqe[space_check.sectors_to_write];
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for (i = 0; i < space_check.sectors_to_write; i++)
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{
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BS_SUBMIT_GET_SQE_DECL(sqe[i]);
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}
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// Prepare and submit journal entries
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auto cb = [this, op](ring_data_t *data) { handle_stable_event(data, op); };
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int s = 0, cur_sector = -1;
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for (i = 0, v = (obj_ver_id*)op->buf; i < op->len; i++, v++)
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{
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// FIXME: Only stabilize versions that aren't stable yet
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if (!journal.entry_fits(sizeof(journal_entry_stable)) &&
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journal.sector_info[journal.cur_sector].dirty)
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{
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if (cur_sector == -1)
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PRIV(op)->min_flushed_journal_sector = 1 + journal.cur_sector;
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prepare_journal_sector_write(journal, journal.cur_sector, sqe[s++], cb);
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cur_sector = journal.cur_sector;
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}
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journal_entry_stable *je = (journal_entry_stable*)
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prefill_single_journal_entry(journal, JE_STABLE, sizeof(journal_entry_stable));
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je->oid = v->oid;
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je->version = v->version;
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je->crc32 = je_crc32((journal_entry*)je);
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journal.crc32_last = je->crc32;
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}
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prepare_journal_sector_write(journal, journal.cur_sector, sqe[s++], cb);
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assert(s == space_check.sectors_to_write);
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if (cur_sector == -1)
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PRIV(op)->min_flushed_journal_sector = 1 + journal.cur_sector;
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PRIV(op)->max_flushed_journal_sector = 1 + journal.cur_sector;
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PRIV(op)->pending_ops = s;
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PRIV(op)->op_state = 1;
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return 1;
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}
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int blockstore_impl_t::continue_stable(blockstore_op_t *op)
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{
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if (PRIV(op)->op_state == 2)
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goto resume_2;
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else if (PRIV(op)->op_state == 3)
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goto resume_3;
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else if (PRIV(op)->op_state == 5)
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goto resume_5;
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else
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return 1;
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resume_2:
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// Release used journal sectors
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release_journal_sectors(op);
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resume_3:
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if (!disable_journal_fsync)
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{
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io_uring_sqe *sqe = get_sqe();
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if (!sqe)
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{
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return 0;
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}
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ring_data_t *data = ((ring_data_t*)sqe->user_data);
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my_uring_prep_fsync(sqe, journal.fd, IORING_FSYNC_DATASYNC);
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data->iov = { 0 };
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data->callback = [this, op](ring_data_t *data) { handle_stable_event(data, op); };
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PRIV(op)->min_flushed_journal_sector = PRIV(op)->max_flushed_journal_sector = 0;
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PRIV(op)->pending_ops = 1;
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PRIV(op)->op_state = 4;
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return 1;
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}
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resume_5:
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// Mark dirty_db entries as stable, acknowledge op completion
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obj_ver_id* v;
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int i;
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for (i = 0, v = (obj_ver_id*)op->buf; i < op->len; i++, v++)
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{
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// Mark all dirty_db entries up to op->version as stable
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mark_stable(*v);
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}
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// Acknowledge op
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op->retval = 0;
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FINISH_OP(op);
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return 1;
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}
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void blockstore_impl_t::mark_stable(const obj_ver_id & v)
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{
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auto dirty_it = dirty_db.find(v);
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if (dirty_it != dirty_db.end())
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{
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while (1)
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{
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if ((dirty_it->second.state & BS_ST_WORKFLOW_MASK) == BS_ST_SYNCED)
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{
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dirty_it->second.state = (dirty_it->second.state & ~BS_ST_WORKFLOW_MASK) | BS_ST_STABLE;
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}
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else if (IS_STABLE(dirty_it->second.state))
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{
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break;
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}
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if (dirty_it == dirty_db.begin())
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{
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break;
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}
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dirty_it--;
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if (dirty_it->first.oid != v.oid)
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{
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break;
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}
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}
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flusher->enqueue_flush(v);
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}
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auto unstab_it = unstable_writes.find(v.oid);
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if (unstab_it != unstable_writes.end() &&
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unstab_it->second <= v.version)
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{
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unstable_writes.erase(unstab_it);
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}
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}
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void blockstore_impl_t::handle_stable_event(ring_data_t *data, blockstore_op_t *op)
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{
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live = true;
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if (data->res != data->iov.iov_len)
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{
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throw std::runtime_error(
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"write operation failed ("+std::to_string(data->res)+" != "+std::to_string(data->iov.iov_len)+
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"). in-memory state is corrupted. AAAAAAAaaaaaaaaa!!!111"
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);
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}
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PRIV(op)->pending_ops--;
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if (PRIV(op)->pending_ops == 0)
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{
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PRIV(op)->op_state++;
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if (!continue_stable(op))
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{
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submit_queue.push_front(op);
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}
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}
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}
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