Illumos 4757, 4913

4757 ZFS embedded-data block pointers ("zero block compression")
4913 zfs release should not be subject to space checks

Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Max Grossman <max.grossman@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Approved by: Dan McDonald <danmcd@omniti.com>

References:
  https://www.illumos.org/issues/4757
  https://www.illumos.org/issues/4913
  https://github.com/illumos/illumos-gate/commit/5d7b4d4

Porting notes:

For compatibility with the fastpath code the zio_done() function
needed to be updated.  Because embedded-data block pointers do
not require DVAs to be allocated the associated vdevs will not
be marked and therefore should not be unmarked.

Ported by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2544

module/zfs/dnode_sync.c

@@ -237,8 +237,6 @@ free_verify(dmu_buf_impl_t *db, uint64_t start, uint64_t end, dmu_tx_t *tx)
 }
 #endif
 
-#define	ALL -1
-
 static void
 free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks,
     dmu_tx_t *tx)
@@ -601,11 +599,14 @@ dnode_sync(dnode_t *dn, dmu_tx_t *tx)
 		dnp->dn_bonustype = dn->dn_bonustype;
 		dnp->dn_bonuslen = dn->dn_bonuslen;
 	}
-
 	ASSERT(dnp->dn_nlevels > 1 ||
 	    BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
+	    BP_IS_EMBEDDED(&dnp->dn_blkptr[0]) ||
 	    BP_GET_LSIZE(&dnp->dn_blkptr[0]) ==
 	    dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT);
+	ASSERT(dnp->dn_nlevels < 2 ||
+	    BP_IS_HOLE(&dnp->dn_blkptr[0]) ||
+	    BP_GET_LSIZE(&dnp->dn_blkptr[0]) == 1 << dnp->dn_indblkshift);
 
 	if (dn->dn_next_type[txgoff] != 0) {
 		dnp->dn_type = dn->dn_type;