os/newstore: fix _txc_aio_submit

The aios may complete before _txc_aio_submit completes.  In fact, the aio
may complete, commit to the kv store, and then queue more wal aio's before
we finish the loop.  Move aios to a separate list to ensure we only submit
them once and do not right another CPU adjusting the list.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/os/newstore/NewStore.cc b/src/os/newstore/NewStore.cc
index a9ece6da05a50b29d7a4f2105871ec61965d2274..17109ba9645f8fc972c7260e7eeeb4ed90824910 100644 (file)
--- a/src/os/newstore/NewStore.cc
+++ b/src/os/newstore/NewStore.cc
@@ -2056,7 +2056,7 @@ void NewStore::_txc_state_proc(TransContext *txc)
             << " " << txc->get_state_name() << dendl;
     switch (txc->state) {
     case TransContext::STATE_PREPARE:
-      if (!txc->aios.empty()) {
+      if (!txc->pending_aios.empty()) {
        txc->state = TransContext::STATE_AIO_WAIT;
        _txc_aio_submit(txc);
        return;
@@ -2107,7 +2107,7 @@ void NewStore::_txc_state_proc(TransContext *txc)
       break;
 
     case TransContext::STATE_WAL_APPLYING:
-      if (!txc->aios.empty()) {
+      if (!txc->pending_aios.empty()) {
        txc->state = TransContext::STATE_WAL_AIO_WAIT;
        _txc_aio_submit(txc);
        return;
@@ -2407,7 +2407,7 @@ int NewStore::_wal_apply(TransContext *txc)
   dout(20) << __func__ << " txc " << txc << " seq " << wt.seq << dendl;
   txc->state = TransContext::STATE_WAL_APPLYING;
 
-  txc->aios.clear();
+  assert(txc->pending_aios.empty());
   int r = _do_wal_transaction(wt, txc);
   assert(r == 0);
 
@@ -2464,8 +2464,8 @@ int NewStore::_do_wal_transaction(wal_transaction_t& wt,
          return fd;
 #ifdef HAVE_LIBAIO
        if (g_conf->newstore_aio && txc && (flags & O_DIRECT)) {
-         txc->aios.push_back(FS::aio_t(txc, fd));
-         FS::aio_t& aio = txc->aios.back();
+         txc->pending_aios.push_back(FS::aio_t(txc, fd));
+         FS::aio_t& aio = txc->pending_aios.back();
          p->data.prepare_iov(&aio.iov);
          aio.pwritev(p->offset);
          dout(2) << __func__ << " prepared aio " << &aio << dendl;
@@ -2642,13 +2642,19 @@ int NewStore::queue_transactions(
 
 void NewStore::_txc_aio_submit(TransContext *txc)
 {
-  int num = txc->aios.size();
+  int num = txc->pending_aios.size();
   dout(10) << __func__ << " txc " << txc << " submitting " << num << dendl;
   assert(num > 0);
   txc->num_aio.set(num);
-  for (list<FS::aio_t>::iterator p = txc->aios.begin();
-       p != txc->aios.end();
-       ++p) {
+
+  // move these aside, and get our end iterator position now, as the
+  // aios might complete as soon as they are submitted and queue more
+  // wal aio's.
+  list<FS::aio_t>::iterator e = txc->submitted_aios.begin();
+  txc->submitted_aios.splice(e, txc->pending_aios);
+  list<FS::aio_t>::iterator p = txc->submitted_aios.begin();
+  assert(p != e);
+  for (; p != e; ++p) {
     FS::aio_t& aio = *p;
     dout(20) << __func__ << " aio " << &aio << " fd " << aio.fd << dendl;
     for (vector<iovec>::iterator q = aio.iov.begin(); q != aio.iov.end(); ++q)
@@ -3257,8 +3263,8 @@ int NewStore::_do_write(TransContext *txc,
     }
 #ifdef HAVE_LIBAIO
     if (g_conf->newstore_aio && (flags & O_DIRECT)) {
-      txc->aios.push_back(FS::aio_t(txc, fd));
-      FS::aio_t& aio = txc->aios.back();
+      txc->pending_aios.push_back(FS::aio_t(txc, fd));
+      FS::aio_t& aio = txc->pending_aios.back();
       bl.prepare_iov(&aio.iov);
       txc->aio_bl.append(bl);
       aio.pwritev(x_offset);
@@ -3305,8 +3311,8 @@ int NewStore::_do_write(TransContext *txc,
 
 #ifdef HAVE_LIBAIO
     if (g_conf->newstore_aio && (flags & O_DIRECT)) {
-      txc->aios.push_back(FS::aio_t(txc, fd));
-      FS::aio_t& aio = txc->aios.back();
+      txc->pending_aios.push_back(FS::aio_t(txc, fd));
+      FS::aio_t& aio = txc->pending_aios.back();
       bl.prepare_iov(&aio.iov);
       txc->aio_bl.append(bl);
       aio.pwritev(0);

diff --git a/src/os/newstore/NewStore.h b/src/os/newstore/NewStore.h
index 9f97122045fac067b93c5f3c8836cab3508d289d..55b73f7fd0b9ea6a05f8fb34bc8b1a8a4a8298da 100644 (file)
--- a/src/os/newstore/NewStore.h
+++ b/src/os/newstore/NewStore.h
@@ -200,7 +200,8 @@ public:
     wal_transaction_t *wal_txn; ///< wal transaction (if any)
     unsigned num_fsyncs_completed;
 
-    list<FS::aio_t> aios;
+    list<FS::aio_t> pending_aios;    ///< not yet submitted
+    list<FS::aio_t> submitted_aios;  ///< submitting or submitted
     bufferlist aio_bl;  // just a pile of refs
     atomic_t num_aio;