Move the handling of PG_PAGEOUT from uvm_aio_aiodone_pages() to

uvm_page_unbusy() so that all callers of uvm_page_unbusy() don't need to
handle this flag separately.  Split out the pages part of uvm_aio_aiodone()
into uvm_aio_aiodone_pages() in rump just like in the real kernel.
In ZFS functions that can fail to copy data between the ARC and VM pages,
use uvm_aio_aiodone_pages() rather than uvm_page_unbusy() so that we can
handle these "I/O" errors.  Fixes PR 55702.

sys/rump/librump/rumpvfs/vm_vfs.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: vm_vfs.c,v 1.38 2020/02/23 15:46:42 ad Exp $	*/
+/*	$NetBSD: vm_vfs.c,v 1.39 2020/10/18 18:22:29 chs Exp $	*/
 
 /*
  * Copyright (c) 2008-2011 Antti Kantee.  All Rights Reserved.
@@ -26,7 +26,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vm_vfs.c,v 1.38 2020/02/23 15:46:42 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vm_vfs.c,v 1.39 2020/10/18 18:22:29 chs Exp $");
 
 #include <sys/param.h>
 
@@ -36,19 +36,37 @@ __KERNEL_RCSID(0, "$NetBSD: vm_vfs.c,v 1.38 2020/02/23 15:46:42 ad Exp $");
 #include <uvm/uvm.h>
 #include <uvm/uvm_readahead.h>
 
+void
+uvm_aio_aiodone_pages(struct vm_page **pgs, int npages, bool write, int error)
+{
+	struct uvm_object *uobj = pgs[0]->uobject;
+	struct vm_page *pg;
+	int i;
+
+	rw_enter(uobj->vmobjlock, RW_WRITER);
+	for (i = 0; i < npages; i++) {
+		pg = pgs[i];
+		KASSERT((pg->flags & PG_FAKE) == 0);
+	}
+	uvm_page_unbusy(pgs, npages);
+	rw_exit(uobj->vmobjlock);
+}
+
 /*
- * release resources held during async io.  this is almost the
+ * Release resources held during async io.
- * same as uvm_aio_aiodone() from uvm_pager.c and only lacks the
- * call to uvm_aio_aiodone_pages(): unbusies pages directly here.
  */
 void
 uvm_aio_aiodone(struct buf *bp)
 {
 	struct uvm_object *uobj = NULL;
-	int i, npages = bp->b_bufsize >> PAGE_SHIFT;
+	int npages = bp->b_bufsize >> PAGE_SHIFT;
 	struct vm_page **pgs;
 	vaddr_t va;
-	int pageout = 0;
+	int i, error;
+	bool write;
+
+	error = bp->b_error;
+	write = BUF_ISWRITE(bp);
 
 	KASSERT(npages > 0);
 	pgs = kmem_alloc(npages * sizeof(*pgs), KM_SLEEP);
@@ -59,27 +77,15 @@ uvm_aio_aiodone(struct buf *bp)
 		if (uobj == NULL) {
 			uobj = pgs[i]->uobject;
 			KASSERT(uobj != NULL);
-			rw_enter(uobj->vmobjlock, RW_WRITER);
 		} else {
 			KASSERT(uobj == pgs[i]->uobject);
 		}
-
-		if (pgs[i]->flags & PG_PAGEOUT) {
-			KASSERT((pgs[i]->flags & PG_FAKE) == 0);
-			pageout++;
-			pgs[i]->flags &= ~PG_PAGEOUT;
-			pgs[i]->flags |= PG_RELEASED;
-		}
 	}
-	KASSERT(rw_write_held(uobj->vmobjlock));
-
-	uvm_page_unbusy(pgs, npages);
-	rw_exit(uobj->vmobjlock);
-
 	uvm_pagermapout((vaddr_t)bp->b_data, npages);
-	uvm_pageout_done(pageout);
 
-	if (BUF_ISWRITE(bp) && (bp->b_cflags & BC_AGE) != 0) {
+	uvm_aio_aiodone_pages(pgs, npages, write, error);
+
+	if (write && (bp->b_cflags & BC_AGE) != 0) {
 		mutex_enter(bp->b_objlock);
 		vwakeup(bp);
 		mutex_exit(bp->b_objlock);

sys/uvm/uvm_page.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: uvm_page.c,v 1.247 2020/09/20 10:30:05 skrll Exp $	*/
+/*	$NetBSD: uvm_page.c,v 1.248 2020/10/18 18:22:29 chs Exp $	*/
 
 /*-
  * Copyright (c) 2019, 2020 The NetBSD Foundation, Inc.
@@ -95,7 +95,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_page.c,v 1.247 2020/09/20 10:30:05 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_page.c,v 1.248 2020/10/18 18:22:29 chs Exp $");
 
 #include "opt_ddb.h"
 #include "opt_uvm.h"
@@ -1602,9 +1602,10 @@ void
 uvm_page_unbusy(struct vm_page **pgs, int npgs)
 {
 	struct vm_page *pg;
-	int i;
+	int i, pageout_done;
 	UVMHIST_FUNC(__func__); UVMHIST_CALLED(ubchist);
 
+	pageout_done = 0;
 	for (i = 0; i < npgs; i++) {
 		pg = pgs[i];
 		if (pg == NULL || pg == PGO_DONTCARE) {
@@ -1613,7 +1614,13 @@ uvm_page_unbusy(struct vm_page **pgs, int npgs)
 
 		KASSERT(uvm_page_owner_locked_p(pg, true));
 		KASSERT(pg->flags & PG_BUSY);
-		KASSERT((pg->flags & PG_PAGEOUT) == 0);
+
+		if (pg->flags & PG_PAGEOUT) {
+			pg->flags &= ~PG_PAGEOUT;
+			pg->flags |= PG_RELEASED;
+			pageout_done++;
+			atomic_inc_uint(&uvmexp.pdfreed);
+		}
 		if (pg->flags & PG_RELEASED) {
 			UVMHIST_LOG(ubchist, "releasing pg %#jx",
 			    (uintptr_t)pg, 0, 0, 0);
@@ -1632,6 +1639,9 @@ uvm_page_unbusy(struct vm_page **pgs, int npgs)
 			UVM_PAGE_OWN(pg, NULL);
 		}
 	}
+	if (pageout_done != 0) {
+		uvm_pageout_done(pageout_done);
+	}
 }
 
 /*

sys/uvm/uvm_pager.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: uvm_pager.c,v 1.129 2020/08/14 09:06:15 chs Exp $	*/
+/*	$NetBSD: uvm_pager.c,v 1.130 2020/10/18 18:22:29 chs Exp $	*/
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_pager.c,v 1.129 2020/08/14 09:06:15 chs Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_pager.c,v 1.130 2020/10/18 18:22:29 chs Exp $");
 
 #include "opt_uvmhist.h"
 #include "opt_readahead.h"
@@ -456,18 +456,6 @@ uvm_aio_aiodone_pages(struct vm_page **pgs, int npages, bool write, int error)
 			uvm_pageunlock(pg);
 		}
 
-		/*
-		 * do accounting for pagedaemon i/o and arrange to free
-		 * the pages instead of just unbusying them.
-		 */
-
-		if (pg->flags & PG_PAGEOUT) {
-			pg->flags &= ~PG_PAGEOUT;
-			pageout_done++;
-			atomic_inc_uint(&uvmexp.pdfreed);
-			pg->flags |= PG_RELEASED;
-		}
-
 #if defined(VMSWAP)
 		/*
 		 * for swap pages, unlock everything for this page now.