Fix object reclaim when using large dnodes

Currently, when the receive_object() code wants to reclaim an
object, it always assumes that the dnode is the legacy 512 bytes,
even when the incoming bonus buffer exceeds this length. This
causes a buffer overflow if --enable-debug is not provided and
triggers an ASSERT if it is. This patch resolves this issue and
adds an ASSERT to ensure this can't happen again.

Fixes: #7097

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

module/zfs/dmu_object.c

@@ -249,7 +249,7 @@ dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
 {
 	return (dmu_object_reclaim_dnsize(os, object, ot, blocksize, bonustype,
-	    bonuslen, 0, tx));
+	    bonuslen, DNODE_MIN_SIZE, tx));
 }
 
 int

module/zfs/dmu_send.c

@@ -2621,9 +2621,10 @@ receive_object(struct receive_writer_arg *rwa, struct drr_object *drro,
 	    drro->drr_bonustype != doi.doi_bonus_type ||
 	    drro->drr_bonuslen != doi.doi_bonus_size) {
 		/* currently allocated, but with different properties */
-		err = dmu_object_reclaim(rwa->os, drro->drr_object,
+		err = dmu_object_reclaim_dnsize(rwa->os, drro->drr_object,
 		    drro->drr_type, drro->drr_blksz,
-		    drro->drr_bonustype, drro->drr_bonuslen, tx);
+		    drro->drr_bonustype, drro->drr_bonuslen,
+		    drro->drr_dn_slots << DNODE_SHIFT, tx);
 	}
 	if (err != 0) {
 		dmu_tx_commit(tx);

module/zfs/dnode.c

@@ -676,8 +676,7 @@ dnode_reallocate(dnode_t *dn, dmu_object_type_t ot, int blocksize,
 	ASSERT(DMU_OT_IS_VALID(bonustype));
 	ASSERT3U(bonuslen, <=,
 	    DN_BONUS_SIZE(spa_maxdnodesize(dmu_objset_spa(dn->dn_objset))));
-
-	dn_slots = dn_slots > 0 ? dn_slots : DNODE_MIN_SLOTS;
+	ASSERT3U(bonuslen, <=, DN_BONUS_SIZE(dn_slots << DNODE_SHIFT));
 
 	dnode_free_interior_slots(dn);
 	DNODE_STAT_BUMP(dnode_reallocate);

tests/zfs-tests/tests/functional/rsend/send_realloc_dnode_size.ksh

@@ -13,6 +13,7 @@
 
 #
 # Copyright (c) 2017 by Lawrence Livermore National Security, LLC.
+# Copyright (c) 2018 Datto Inc.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -31,8 +32,10 @@
 # 3. Remove objects, set dnodesize=2k, and remount dataset so new objects
 #    overlap with recently recycled and formerly "normal" dnode slots get
 #    assigned to new objects
-# 4. Generate initial and incremental streams
-# 5. Verify initial and incremental streams can be received
+# 4. Create an empty file and add xattrs to it to exercise reclaiming a
+#    dnode that requires more than 1 slot for its bonus buffer (Zol #7433)
+# 5. Generate initial and incremental streams
+# 6. Verify initial and incremental streams can be received
 #
 
 verify_runnable "both"
@@ -44,6 +47,7 @@ function cleanup
 	rm -f $BACKDIR/fs-dn-legacy
 	rm -f $BACKDIR/fs-dn-1k
 	rm -f $BACKDIR/fs-dn-2k
+	rm -f $BACKDIR/fs-attr
 
 	if datasetexists $POOL/fs ; then
 		log_must zfs destroy -rR $POOL/fs
@@ -82,17 +86,26 @@ log_must zfs unmount $POOL/fs
 log_must zfs set dnodesize=2k $POOL/fs
 log_must zfs mount $POOL/fs
 
+log_must touch /$POOL/fs/attrs
 mk_files 200 262144 0 $POOL/fs
 log_must zfs snapshot $POOL/fs@c
 
-# 4. Generate initial and incremental streams
+# 4. Create an empty file and add xattrs to it to exercise reclaiming a
+#    dnode that requires more than 1 slot for its bonus buffer (Zol #7433)
+log_must zfs set compression=on xattr=sa $POOL/fs
+log_must eval "python -c 'print \"a\" * 512' | attr -s bigval /$POOL/fs/attrs"
+log_must zfs snapshot $POOL/fs@d
+
+# 5. Generate initial and incremental streams
 log_must eval "zfs send $POOL/fs@a > $BACKDIR/fs-dn-1k"
 log_must eval "zfs send -i $POOL/fs@a $POOL/fs@b > $BACKDIR/fs-dn-legacy"
 log_must eval "zfs send -i $POOL/fs@b $POOL/fs@c > $BACKDIR/fs-dn-2k"
+log_must eval "zfs send -i $POOL/fs@c $POOL/fs@d > $BACKDIR/fs-attr"
 
-# 5. Verify initial and incremental streams can be received
+# 6. Verify initial and incremental streams can be received
 log_must eval "zfs recv $POOL/newfs < $BACKDIR/fs-dn-1k"
 log_must eval "zfs recv $POOL/newfs < $BACKDIR/fs-dn-legacy"
 log_must eval "zfs recv $POOL/newfs < $BACKDIR/fs-dn-2k"
+log_must eval "zfs recv $POOL/newfs < $BACKDIR/fs-attr"
 
 log_pass "Verify incremental receive handles objects with changed dnode size"