MFV r247580:

Merge synctask code restructuring from vendor.

Modify forward and backward compatibility to support new change.

Illumos ZFS issues:
  3464 zfs synctask code needs restructuring

Sponsored by:	Hybrid Logic Ltd.

1 files changed, 16 insertions, 15 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c
index 556ae6a..8e6beec 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c
@@ -898,7 +898,7 @@ dmu_tx_dirty_buf(dmu_tx_t *tx, dmu_buf_impl_t *db)
 #endif
 
 static int
-dmu_tx_try_assign(dmu_tx_t *tx, uint64_t txg_how)
+dmu_tx_try_assign(dmu_tx_t *tx, txg_how_t txg_how)
 {
 	dmu_tx_hold_t *txh;
 	spa_t *spa = tx->tx_pool->dp_spa;
@@ -962,13 +962,6 @@ dmu_tx_try_assign(dmu_tx_t *tx, uint64_t txg_how)
 	}
 
 	/*
-	 * NB: This check must be after we've held the dnodes, so that
-	 * the dmu_tx_unassign() logic will work properly
-	 */
-	if (txg_how >= TXG_INITIAL && txg_how != tx->tx_txg)
-		return (ERESTART);
-
-	/*
 	 * If a snapshot has been taken since we made our estimates,
 	 * assume that we won't be able to free or overwrite anything.
 	 */
@@ -1048,26 +1041,25 @@ dmu_tx_unassign(dmu_tx_t *tx)
  *
  * (1)	TXG_WAIT.  If the current open txg is full, waits until there's
  *	a new one.  This should be used when you're not holding locks.
- *	If will only fail if we're truly out of space (or over quota).
+ *	It will only fail if we're truly out of space (or over quota).
  *
  * (2)	TXG_NOWAIT.  If we can't assign into the current open txg without
  *	blocking, returns immediately with ERESTART.  This should be used
  *	whenever you're holding locks.  On an ERESTART error, the caller
  *	should drop locks, do a dmu_tx_wait(tx), and try again.
- *
- * (3)	A specific txg.  Use this if you need to ensure that multiple
- *	transactions all sync in the same txg.  Like TXG_NOWAIT, it
- *	returns ERESTART if it can't assign you into the requested txg.
  */
 int
-dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how)
+dmu_tx_assign(dmu_tx_t *tx, txg_how_t txg_how)
 {
 	int err;
 
 	ASSERT(tx->tx_txg == 0);
-	ASSERT(txg_how != 0);
+	ASSERT(txg_how == TXG_WAIT || txg_how == TXG_NOWAIT);
 	ASSERT(!dsl_pool_sync_context(tx->tx_pool));
 
+	/* If we might wait, we must not hold the config lock. */
+	ASSERT(txg_how != TXG_WAIT || !dsl_pool_config_held(tx->tx_pool));
+
 	while ((err = dmu_tx_try_assign(tx, txg_how)) != 0) {
 		dmu_tx_unassign(tx);
 
@@ -1088,6 +1080,7 @@ dmu_tx_wait(dmu_tx_t *tx)
 	spa_t *spa = tx->tx_pool->dp_spa;
 
 	ASSERT(tx->tx_txg == 0);
+	ASSERT(!dsl_pool_config_held(tx->tx_pool));
 
 	/*
 	 * It's possible that the pool has become active after this thread
@@ -1214,6 +1207,14 @@ dmu_tx_get_txg(dmu_tx_t *tx)
 	return (tx->tx_txg);
 }
 
+dsl_pool_t *
+dmu_tx_pool(dmu_tx_t *tx)
+{
+	ASSERT(tx->tx_pool != NULL);
+	return (tx->tx_pool);
+}
+
+
 void
 dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *func, void *data)
 {