svn commit: r253187 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Thu Jul 11 05:36:26 2013
New Revision: 253187
URL: http://svnweb.freebsd.org/changeset/base/253187

Log:
  Do not invalidate page of the B_NOCACHE buffer or buffer after an I/O
  error if any user wired mappings exist.  Doing the invalidation
  destroys the user wiring.
  
  The change is the temporal measure to close the bug, the more proper
  fix is to delegate the invalidation of the page to upper layers
  always.
  
  Reported and tested by:	pho
  Reviewed by:	alc
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks

Modified:
  head/sys/kern/vfs_bio.c

Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c	Thu Jul 11 05:15:30 2013	(r253186)
+++ head/sys/kern/vfs_bio.c	Thu Jul 11 05:36:26 2013	(r253187)
@@ -1692,7 +1692,8 @@ brelse(struct buf *bp)
 
 				KASSERT(presid >= 0, ("brelse: extra page"));
 				VM_OBJECT_WLOCK(obj);
-				vm_page_set_invalid(m, poffset, presid);
+				if (pmap_page_wired_mappings(m) == 0)
+					vm_page_set_invalid(m, poffset, presid);
 				VM_OBJECT_WUNLOCK(obj);
 				if (had_bogus)
 					printf("avoided corruption bug in bogus_page/brelse code\n");