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

1 files changed, 11 insertions, 50 deletions

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 95f8929..762b253 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -3013,63 +3013,24 @@ allocbuf(struct buf *bp, int size)
 			VM_OBJECT_LOCK(obj);
 			while (bp->b_npages < desiredpages) {
 				vm_page_t m;
-				vm_pindex_t pi;
-
-				pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
-				if ((m = vm_page_lookup(obj, pi)) == NULL) {
-					/*
-					 * note: must allocate system pages
-					 * since blocking here could intefere
-					 * with paging I/O, no matter which
-					 * process we are.
-					 */
-					m = vm_page_alloc(obj, pi,
-					    VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
-					    VM_ALLOC_WIRED);
-					if (m == NULL) {
-						atomic_add_int(&vm_pageout_deficit,
-						    desiredpages - bp->b_npages);
-						VM_OBJECT_UNLOCK(obj);
-						VM_WAIT;
-						VM_OBJECT_LOCK(obj);
-					} else {
-						if (m->valid == 0)
-							bp->b_flags &= ~B_CACHE;
-						bp->b_pages[bp->b_npages] = m;
-						++bp->b_npages;
-					}
-					continue;
-				}
 
 				/*
-				 * We found a page.  If we have to sleep on it,
-				 * retry because it might have gotten freed out
-				 * from under us.
+				 * We must allocate system pages since blocking
+				 * here could intefere with paging I/O, no
+				 * matter which process we are.
 				 *
 				 * We can only test VPO_BUSY here.  Blocking on
 				 * m->busy might lead to a deadlock:
-				 *
 				 *  vm_fault->getpages->cluster_read->allocbuf
-				 *
-				 */
-				if ((m->oflags & VPO_BUSY) != 0) {
-					/*
-					 * Reference the page before unlocking
-					 * and sleeping so that the page daemon
-					 * is less likely to reclaim it.  
-					 */
-					vm_page_lock_queues();
-					vm_page_flag_set(m, PG_REFERENCED);
-					vm_page_sleep(m, "pgtblk");
-					continue;
-				}
-
-				/*
-				 * We have a good page.
+				 * Thus, we specify VM_ALLOC_IGN_SBUSY.
 				 */
-				vm_page_lock(m);
-				vm_page_wire(m);
-				vm_page_unlock(m);
+				m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
+				    bp->b_npages, VM_ALLOC_NOBUSY |
+				    VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
+				    VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY |
+				    VM_ALLOC_COUNT(desiredpages - bp->b_npages));
+				if (m->valid == 0)
+					bp->b_flags &= ~B_CACHE;
 				bp->b_pages[bp->b_npages] = m;
 				++bp->b_npages;
 			}