Fixes for #6639

Several issues were uncovered by running stress tests with zfs
encryption and raw sends in particular. The issues and their
associated fixes are as follows:

* arc_read_done() has the ability to chain several requests for
  the same block of data via the arc_callback_t struct. In these
  cases, the ARC would only use the first request's dsobj from
  the bookmark to decrypt the data. This is problematic because
  the first request might be a prefetch zio which is able to
  handle the key not being loaded, while the second might use a
  different key that it is sure will work. The fix here is to
  pass the dsobj with each individual arc_callback_t so that each
  request can attempt to decrypt the data separately.

* DRR_FREE and DRR_FREEOBJECT records in a send file were not
  having their transactions properly tagged as raw during raw
  sends, which caused a panic when the dbuf code attempted to
  decrypt these blocks.

* traverse_prefetch_metadata() did not properly set
  ZIO_FLAG_SPECULATIVE when issuing prefetch IOs.

* Added a few asserts and code cleanups to ensure these issues
  are more detectable in the future.

Signed-off-by: Tom Caputi <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/module/zfs/dmu_traverse.c b/module/zfs/dmu_traverse.c
index a6c27b4be..268d82ce4 100644
--- a/module/zfs/dmu_traverse.c
+++ b/module/zfs/dmu_traverse.c
@@ -181,7 +181,7 @@ traverse_prefetch_metadata(traverse_data_t *td,
     const blkptr_t *bp, const zbookmark_phys_t *zb)
 {
 	arc_flags_t flags = ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
-	int zio_flags = ZIO_FLAG_CANFAIL;
+	int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE;
 
 	if (!(td->td_flags & TRAVERSE_PREFETCH_METADATA))
 		return;