6948911 snapshot deletion can induce unsatisfiable allocations in txg sync

3 files changed, 16 insertions, 6 deletions

diff --git a/usr/src/uts/common/fs/zfs/dsl_dataset.c b/usr/src/uts/common/fs/zfs/dsl_dataset.c
index 1e0ac2c76a..ee0ccd7d01 100644
--- a/usr/src/uts/common/fs/zfs/dsl_dataset.c
+++ b/usr/src/uts/common/fs/zfs/dsl_dataset.c
@@ -1598,6 +1598,7 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 
 	if (ds->ds_phys->ds_next_snap_obj != 0) {
 		blkptr_t bp;
+		zio_t *pio;
 		dsl_dataset_t *ds_next;
 		uint64_t itor = 0;
 		uint64_t old_unique;
@@ -1617,6 +1618,8 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		ASSERT3U(ds->ds_phys->ds_prev_snap_txg, ==,
 		    ds_prev ? ds_prev->ds_phys->ds_creation_txg : 0);
 
+		pio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
+
 		/*
 		 * Transfer to our deadlist (which will become next's
 		 * new deadlist) any entries from next's current
@@ -1639,10 +1642,10 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 				used += bp_get_dsize_sync(dp->dp_spa, &bp);
 				compressed += BP_GET_PSIZE(&bp);
 				uncompressed += BP_GET_UCSIZE(&bp);
-				dsl_free(dp, tx->tx_txg, &bp);
+				dsl_free_sync(pio, dp, tx->tx_txg, &bp);
 			}
 		}
-
+		VERIFY3U(zio_wait(pio), ==, 0);
 		ASSERT3U(used, ==, ds->ds_phys->ds_unique_bytes);
 
 		/* change snapused */
diff --git a/usr/src/uts/common/fs/zfs/dsl_scrub.c b/usr/src/uts/common/fs/zfs/dsl_scrub.c
index 269e1c4f6f..b16ff66586 100644
--- a/usr/src/uts/common/fs/zfs/dsl_scrub.c
+++ b/usr/src/uts/common/fs/zfs/dsl_scrub.c
@@ -19,8 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
 #include <sys/dsl_pool.h>
@@ -272,6 +271,13 @@ dsl_free(dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp)
 	zio_free(dp->dp_spa, txg, bpp);
 }
 
+void
+dsl_free_sync(zio_t *pio, dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp)
+{
+	ASSERT(dsl_pool_sync_context(dp));
+	zio_nowait(zio_free_sync(pio, dp->dp_spa, txg, bpp, pio->io_flags));
+}
+
 static boolean_t
 bookmark_is_zero(const zbookmark_t *zb)
 {
diff --git a/usr/src/uts/common/fs/zfs/sys/dsl_pool.h b/usr/src/uts/common/fs/zfs/sys/dsl_pool.h
index 4e49d212a3..97541ad2f1 100644
--- a/usr/src/uts/common/fs/zfs/sys/dsl_pool.h
+++ b/usr/src/uts/common/fs/zfs/sys/dsl_pool.h
@@ -19,8 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
 #ifndef	_SYS_DSL_POOL_H
@@ -137,6 +136,8 @@ void dsl_pool_tempreserve_clear(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx);
 void dsl_pool_memory_pressure(dsl_pool_t *dp);
 void dsl_pool_willuse_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx);
 void dsl_free(dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp);
+void dsl_free_sync(zio_t *pio, dsl_pool_t *dp, uint64_t txg,
+    const blkptr_t *bpp);
 void dsl_pool_ds_destroyed(struct dsl_dataset *ds, struct dmu_tx *tx);
 void dsl_pool_ds_snapshotted(struct dsl_dataset *ds, struct dmu_tx *tx);
 void dsl_pool_ds_clone_swapped(struct dsl_dataset *ds1, struct dsl_dataset *ds2,