In the VOP_PUTPAGES() implementations, change the default error from

VM_PAGER_AGAIN to VM_PAGER_ERROR for the uwritten pages. Return
VM_PAGER_AGAIN for the partially written page. Always forward at least
one page in the loop of vm_object_page_clean().

VM_PAGER_ERROR causes the page reactivation and does not clear the
page dirty state, so the write is not lost.

The change fixes an infinite loop in vm_object_page_clean() when the
filesystem returns permanent errors for some page writes.

Reported and tested by:	gavin
Reviewed by:	alc, rmacklem
MFC after:	1 week

1 files changed, 18 insertions, 1 deletions

diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index f497d41..98a5be0 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -1089,7 +1089,7 @@ vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
 	count = bytecount / PAGE_SIZE;
 
 	for (i = 0; i < count; i++)
-		rtvals[i] = VM_PAGER_AGAIN;
+		rtvals[i] = VM_PAGER_ERROR;
 
 	if ((int64_t)ma[0]->pindex < 0) {
 		printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%lx)\n",
@@ -1191,3 +1191,20 @@ vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
 	}
 	return rtvals[0];
 }
+
+void
+vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written)
+{
+	int i, pos;
+
+	for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
+		if (pos < trunc_page(written)) {
+			rtvals[i] = VM_PAGER_OK;
+			vm_page_undirty(ma[i]);
+		} else {
+			/* Partially written page. */
+			rtvals[i] = VM_PAGER_AGAIN;
+			vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
+		}
+	}
+}