Add the ability for the allocflag argument of the vm_page_grab() to

specify the increment of vm_pageout_deficit when sleeping due to page
shortage. Then, in allocbuf(), the code to allocate pages when extending
vmio buffer can be replaced by a call to vm_page_grab().

Suggested and reviewed by:	alc
MFC after:	2 weeks

2 files changed, 13 insertions, 2 deletions

diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 6659e76..810338d 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -2038,11 +2038,13 @@ vm_page_t
 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags)
 {
 	vm_page_t m;
+	u_int count;
 
 	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
 retrylookup:
 	if ((m = vm_page_lookup(object, pindex)) != NULL) {
-		if ((m->oflags & VPO_BUSY) != 0 || m->busy != 0) {
+		if ((m->oflags & VPO_BUSY) != 0 ||
+		    ((allocflags & VM_ALLOC_IGN_SBUSY) == 0 && m->busy != 0)) {
 			if ((allocflags & VM_ALLOC_RETRY) != 0) {
 				/*
 				 * Reference the page before unlocking and
@@ -2067,9 +2069,13 @@ retrylookup:
 			return (m);
 		}
 	}
-	m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY);
+	m = vm_page_alloc(object, pindex, allocflags & ~(VM_ALLOC_RETRY |
+	    VM_ALLOC_IGN_SBUSY | VM_ALLOC_COUNT_MASK));
 	if (m == NULL) {
 		VM_OBJECT_UNLOCK(object);
+		count = (u_int)allocflags >> VM_ALLOC_COUNT_SHIFT;
+		if (count > 0)
+			atomic_add_int(&vm_pageout_deficit, count);
 		VM_WAIT;
 		VM_OBJECT_LOCK(object);
 		if ((allocflags & VM_ALLOC_RETRY) == 0)
diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index 1b2f39a..0829025 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -317,6 +317,11 @@ extern struct vpglocks vm_page_queue_lock;
 #define	VM_ALLOC_NOBUSY		0x0200	/* Do not busy the page */
 #define	VM_ALLOC_IFCACHED	0x0400	/* Fail if the page is not cached */
 #define	VM_ALLOC_IFNOTCACHED	0x0800	/* Fail if the page is cached */
+#define	VM_ALLOC_IGN_SBUSY	0x1000	/* vm_page_grab() only */
+
+#define	VM_ALLOC_COUNT_SHIFT	16
+#define	VM_ALLOC_COUNT(count)	((count) << VM_ALLOC_COUNT_SHIFT)
+#define	VM_ALLOC_COUNT_MASK	VM_ALLOC_COUNT(0xffff)
 
 void vm_page_flag_set(vm_page_t m, unsigned short bits);
 void vm_page_flag_clear(vm_page_t m, unsigned short bits);