svn commit: r275922 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Xin LI]

Author: delphij
Date: Thu Dec 18 23:45:26 2014
New Revision: 275922
URL: https://svnweb.freebsd.org/changeset/base/275922

Log:
  MFV r275914:
  
  As of r270383, the dbuf_compare comparator compares the dbuf
  attributes in the following order:
  
  	db_level (indirect level)
  	db_blkid (block number)
  	db_state (current state)
  	the address of the element
  
  Because db_state is being considered before the element's state,
  changing of db_state would affect balancedness of the AVL tree,
  even when the address of element compares differently.  For
  instance, in dbuf_create, db_state may be altered after the
  node is inserted into the AVL tree and may break AVL tree
  balancedness.
  
  Instead of using db_state as a comparision critera (introduced
  in r270383), consider it only when we are doing a lookup, that
  is one of the two dbuf pointers contains DB_SEARCH.
  
  Illumos issue:
      5422 preserve AVL invariants in dn_dbufs
  
  MFC after:	2 weeks

Modified:
  head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c
Directory Properties:
  head/sys/cddl/contrib/opensolaris/   (props changed)

Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c	Thu Dec 18 23:00:17 2014	(r275921)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c	Thu Dec 18 23:45:26 2014	(r275922)
@@ -81,16 +81,14 @@ dbuf_compare(const void *x1, const void 
 		return (1);
 	}
 
-	if (d1->db_state < d2->db_state) {
+	if (d1->db_state == DB_SEARCH) {
+		ASSERT3S(d2->db_state, !=, DB_SEARCH);
 		return (-1);
-	}
-	if (d1->db_state > d2->db_state) {
+	} else if (d2->db_state == DB_SEARCH) {
+		ASSERT3S(d1->db_state, !=, DB_SEARCH);
 		return (1);
 	}
 
-	ASSERT3S(d1->db_state, !=, DB_SEARCH);
-	ASSERT3S(d2->db_state, !=, DB_SEARCH);
-
 	if ((uintptr_t)d1 < (uintptr_t)d2) {
 		return (-1);
 	}