svn commit: r361855 - head/sys/vm

[Chuck Silvers]

Author: chs
Date: Sat Jun  6 00:47:59 2020
New Revision: 361855
URL: https://svnweb.freebsd.org/changeset/base/361855

Log:
  Don't mark pages as valid if reading the contents from disk fails.
  Instead, just skip marking pages valid if the read fails.  Future
  attempts to access such pages will notice that they are not marked valid
  and try to read them from disk again.
  
  Reviewed by:	kib, markj
  Sponsored by:	Netflix
  Differential Revision:	https://reviews.freebsd.org/D25138

Modified:
  head/sys/vm/vnode_pager.c

Modified: head/sys/vm/vnode_pager.c
==============================================================================
--- head/sys/vm/vnode_pager.c	Sat Jun  6 00:40:02 2020	(r361854)
+++ head/sys/vm/vnode_pager.c	Sat Jun  6 00:47:59 2020	(r361855)
@@ -1150,28 +1150,30 @@ vnode_pager_generic_getpages_done(struct buf *bp)
 		if (mt == bogus_page)
 			continue;
 
-		if (nextoff <= object->un_pager.vnp.vnp_size) {
-			/*
-			 * Read filled up entire page.
-			 */
-			vm_page_valid(mt);
-			KASSERT(mt->dirty == 0,
-			    ("%s: page %p is dirty", __func__, mt));
-			KASSERT(!pmap_page_is_mapped(mt),
-			    ("%s: page %p is mapped", __func__, mt));
-		} else {
-			/*
-			 * Read did not fill up entire page.
-			 *
-			 * Currently we do not set the entire page valid,
-			 * we just try to clear the piece that we couldn't
-			 * read.
-			 */
-			vm_page_set_valid_range(mt, 0,
-			    object->un_pager.vnp.vnp_size - tfoff);
-			KASSERT((mt->dirty & vm_page_bits(0,
-			    object->un_pager.vnp.vnp_size - tfoff)) == 0,
-			    ("%s: page %p is dirty", __func__, mt));
+		if (error == 0) {
+			if (nextoff <= object->un_pager.vnp.vnp_size) {
+				/*
+				 * Read filled up entire page.
+				 */
+				vm_page_valid(mt);
+				KASSERT(mt->dirty == 0,
+				    ("%s: page %p is dirty", __func__, mt));
+				KASSERT(!pmap_page_is_mapped(mt),
+				    ("%s: page %p is mapped", __func__, mt));
+			} else {
+				/*
+				 * Read did not fill up entire page.
+				 *
+				 * Currently we do not set the entire page
+				 * valid, we just try to clear the piece that
+				 * we couldn't read.
+				 */
+				vm_page_set_valid_range(mt, 0,
+				    object->un_pager.vnp.vnp_size - tfoff);
+				KASSERT((mt->dirty & vm_page_bits(0,
+				    object->un_pager.vnp.vnp_size - tfoff)) ==
+				    0, ("%s: page %p is dirty", __func__, mt));
+			}
 		}
 
 		if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter)