[src/trunk]: src/sys/uvm ubc_uiomove_direct(): if UBC_FAULTBUSY, the left-ove...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c774102d6a96
branches:  trunk
changeset: 933489:c774102d6a96
user:      ad <ad%NetBSD.org@localhost>
date:      Mon May 25 19:29:08 2020 +0000

description:
ubc_uiomove_direct(): if UBC_FAULTBUSY, the left-over portion of the final
page needs to be zeroed.

diffstat:

 sys/uvm/uvm_bio.c |  42 ++++++++++++++++++++++++++++++------------
 1 files changed, 30 insertions(+), 12 deletions(-)

diffs (69 lines):

diff -r 15294d0a4c3b -r c774102d6a96 sys/uvm/uvm_bio.c
--- a/sys/uvm/uvm_bio.c Mon May 25 19:13:28 2020 +0000
+++ b/sys/uvm/uvm_bio.c Mon May 25 19:29:08 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_bio.c,v 1.116 2020/05/24 20:05:53 ad Exp $ */
+/*     $NetBSD: uvm_bio.c,v 1.117 2020/05/25 19:29:08 ad Exp $ */
 
 /*
  * Copyright (c) 1998 Chuck Silvers.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.116 2020/05/24 20:05:53 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.117 2020/05/25 19:29:08 ad Exp $");
 
 #include "opt_uvmhist.h"
 #include "opt_ubc.h"
@@ -997,22 +997,40 @@
                        error = uvm_direct_process(pgs, npages, off, bytelen,
                            ubc_uiomove_process, uio);
                }
-               if (error != 0 && overwrite) {
+
+               if (overwrite) {
+                       voff_t endoff;
+
                        /*
-                        * if we haven't initialized the pages yet,
-                        * do it now.  it's safe to use memset here
-                        * because we just mapped the pages above.
+                        * if we haven't initialized the pages yet due to an
+                        * error above, do it now.
                         */
-                       printf("%s: error=%d\n", __func__, error);
-                       (void) uvm_direct_process(pgs, npages, off, bytelen,
-                           ubc_zerorange_process, NULL);
+                       if (error != 0) {
+                               printf("%s: error=%d\n", __func__, error);
+                               (void) uvm_direct_process(pgs, npages, off,
+                                   bytelen, ubc_zerorange_process, NULL);
+                       }
+
+                       off += bytelen;
+                       todo -= bytelen;
+                       endoff = off & (PAGE_SIZE - 1);
+
+                       /*
+                        * zero out the remaining portion of the final page
+                        * (if any).
+                        */
+                       if (todo == 0 && endoff != 0) {
+                               vsize_t zlen = PAGE_SIZE - endoff;
+                               (void) uvm_direct_process(pgs + npages - 1, 1,
+                                   off, zlen, ubc_zerorange_process, NULL);
+                       }
+               } else {
+                       off += bytelen;
+                       todo -= bytelen;
                }
 
                ubc_direct_release(uobj, flags, pgs, npages);
 
-               off += bytelen;
-               todo -= bytelen;
-
                if (error != 0 && ISSET(flags, UBC_PARTIALOK)) {
                        break;
                }