svn commit: r244076 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Mon Dec 10 05:14:04 2012
New Revision: 244076
URL: http://svnweb.freebsd.org/changeset/base/244076

Log:
  Do not ignore zero address, possibly returned by the vm_map_find()
  call.  The function indicates a failure by the TRUE return value.  To
  be extra safe, assert that the return value from the following
  vm_map_insert() indicates success.
  
  Fix style issues in the nearby lines, reformulate the comment.
  
  Reviewed by:	alc (previous version)
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/kern/vfs_bio.c

Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c	Mon Dec 10 03:11:19 2012	(r244075)
+++ head/sys/kern/vfs_bio.c	Mon Dec 10 05:14:04 2012	(r244076)
@@ -2107,15 +2107,16 @@ restart:
 
 		if (maxsize != bp->b_kvasize) {
 			vm_offset_t addr = 0;
+			int rv;
 
 			bfreekva(bp);
 
 			vm_map_lock(buffer_map);
 			if (vm_map_findspace(buffer_map,
-				vm_map_min(buffer_map), maxsize, &addr)) {
+			    vm_map_min(buffer_map), maxsize, &addr)) {
 				/*
-				 * Uh oh.  Buffer map is to fragmented.  We
-				 * must defragment the map.
+				 * Buffer map is too fragmented.
+				 * We must defragment the map.
 				 */
 				atomic_add_int(&bufdefragcnt, 1);
 				vm_map_unlock(buffer_map);
@@ -2124,22 +2125,21 @@ restart:
 				brelse(bp);
 				goto restart;
 			}
-			if (addr) {
-				vm_map_insert(buffer_map, NULL, 0,
-					addr, addr + maxsize,
-					VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
-
-				bp->b_kvabase = (caddr_t) addr;
-				bp->b_kvasize = maxsize;
-				atomic_add_long(&bufspace, bp->b_kvasize);
-				atomic_add_int(&bufreusecnt, 1);
-			}
+			rv = vm_map_insert(buffer_map, NULL, 0, addr,
+			    addr + maxsize, VM_PROT_ALL, VM_PROT_ALL,
+			    MAP_NOFAULT);
+			KASSERT(rv == KERN_SUCCESS,
+			    ("vm_map_insert(buffer_map) rv %d", rv));
 			vm_map_unlock(buffer_map);
+			bp->b_kvabase = (caddr_t)addr;
+			bp->b_kvasize = maxsize;
+			atomic_add_long(&bufspace, bp->b_kvasize);
+			atomic_add_int(&bufreusecnt, 1);
 		}
 		bp->b_saveaddr = bp->b_kvabase;
 		bp->b_data = bp->b_saveaddr;
 	}
-	return(bp);
+	return (bp);
 }
 
 /*