From 9a236af3adc50ac9b3bea3ba75aa37009986112b Mon Sep 17 00:00:00 2001
From: Jeff Roberson <jeff@FreeBSD.org>
Date: Sat, 6 Jul 2002 08:59:52 +0000
Subject: [PATCH] Fixup uses of GETVOBJECT.

 - Cache a pointer to the vnode's object in the buf.
 - Hold a reference to that object in addition to the vnode's reference just
   to be consistent.
 - Cleanup code that got the object indirectly through the vp and VOP calls.

This fixes at least one case where we were calling GETVOBJECT without a lock.
It also avoids an expensive layered call at the cost of another pointer in
struct buf.
---
 sys/kern/vfs_bio.c  | 25 ++++++++++---------------
 sys/kern/vfs_subr.c |  4 ++++
 sys/sys/buf.h       |  3 +++
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 30dc7535814f..02b13cf3b9ae 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -1206,6 +1206,7 @@ brelse(struct buf * bp)
 		struct vnode *vp;
 
 		vp = bp->b_vp;
+		obj = bp->b_object;
 
 		/*
 		 * Get the base offset and length of the buffer.  Note that 
@@ -1233,7 +1234,6 @@ brelse(struct buf * bp)
 			 * now.
 			 */
 			if (m == bogus_page) {
-				VOP_GETVOBJECT(vp, &obj);
 				poff = OFF_TO_IDX(bp->b_offset);
 				had_bogus = 1;
 
@@ -1803,6 +1803,7 @@ getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
 		bp->b_dirtyoff = bp->b_dirtyend = 0;
 		bp->b_magic = B_MAGIC_BIO;
 		bp->b_op = &buf_ops_bio;
+		bp->b_object = NULL;
 
 		LIST_INIT(&bp->b_dep);
 
@@ -2423,8 +2424,11 @@ getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
 			if (vp->v_type != VREG)
 				printf("getblk: vmioing file type %d???\n", vp->v_type);
 #endif
+			VOP_GETVOBJECT(vp, &bp->b_object);
+			vm_object_reference(bp->b_object);
 		} else {
 			bp->b_flags &= ~B_VMIO;
+			bp->b_object = NULL;
 		}
 
 		allocbuf(bp, size);
@@ -2628,7 +2632,7 @@ allocbuf(struct buf *bp, int size)
 			 */
 
 			vp = bp->b_vp;
-			VOP_GETVOBJECT(vp, &obj);
+			obj = bp->b_object;
 
 			while (bp->b_npages < desiredpages) {
 				vm_page_t m;
@@ -2813,7 +2817,7 @@ bufdonebio(struct bio *bp)
 void
 bufdone(struct buf *bp)
 {
-	int s, error;
+	int s;
 	void    (*biodone)(struct buf *);
 
 	GIANT_REQUIRED;
@@ -2855,17 +2859,13 @@ bufdone(struct buf *bp)
 		int iosize;
 		struct vnode *vp = bp->b_vp;
 
-		error = VOP_GETVOBJECT(vp, &obj);
+		obj = bp->b_object;
 
 #if defined(VFS_BIO_DEBUG)
 		if (vp->v_usecount == 0) {
 			panic("biodone: zero vnode ref count");
 		}
 
-		if (error) {
-			panic("biodone: missing VM object");
-		}
-
 		if ((vp->v_flag & VOBJBUF) == 0) {
 			panic("biodone: vnode is not setup for merged cache");
 		}
@@ -2875,9 +2875,6 @@ bufdone(struct buf *bp)
 		KASSERT(bp->b_offset != NOOFFSET,
 		    ("biodone: no buffer offset"));
 
-		if (error) {
-			panic("biodone: no object");
-		}
 #if defined(VFS_BIO_DEBUG)
 		if (obj->paging_in_progress < bp->b_npages) {
 			printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
@@ -2999,10 +2996,9 @@ vfs_unbusy_pages(struct buf * bp)
 
 	runningbufwakeup(bp);
 	if (bp->b_flags & B_VMIO) {
-		struct vnode *vp = bp->b_vp;
 		vm_object_t obj;
 
-		VOP_GETVOBJECT(vp, &obj);
+		obj = bp->b_object;
 
 		for (i = 0; i < bp->b_npages; i++) {
 			vm_page_t m = bp->b_pages[i];
@@ -3081,11 +3077,10 @@ vfs_busy_pages(struct buf * bp, int clear_modify)
 	GIANT_REQUIRED;
 
 	if (bp->b_flags & B_VMIO) {
-		struct vnode *vp = bp->b_vp;
 		vm_object_t obj;
 		vm_ooffset_t foff;
 
-		VOP_GETVOBJECT(vp, &obj);
+		obj = bp->b_object;
 		foff = bp->b_offset;
 		KASSERT(bp->b_offset != NOOFFSET,
 		    ("vfs_busy_pages: no buffer offset"));
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 882fc391d557..d8e960a2ba10 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1139,6 +1139,10 @@ brelvp(bp)
 	splx(s);
 	bp->b_vp = (struct vnode *) 0;
 	vdrop(vp);
+	if (bp->b_object) {
+		vm_object_deallocate(bp->b_object);
+		bp->b_object = NULL;
+	}
 }
 
 /*
diff --git a/sys/sys/buf.h b/sys/sys/buf.h
index 0f6f579fd4b1..63532761f535 100644
--- a/sys/sys/buf.h
+++ b/sys/sys/buf.h
@@ -76,6 +76,8 @@ struct buf_ops {
 
 extern struct buf_ops buf_ops_bio;
 
+struct vm_object;
+
 /*
  * The buffer header describes an I/O operation in the kernel.
  *
@@ -128,6 +130,7 @@ struct buf {
 	int	b_kvasize;		/* size of kva for buffer */
 	daddr_t b_lblkno;		/* Logical block number. */
 	struct	vnode *b_vp;		/* Device vnode. */
+	struct	vm_object *b_object;	/* Object for vp */
 	int	b_dirtyoff;		/* Offset in buffer of dirty region. */
 	int	b_dirtyend;		/* Offset of end of dirty region. */
 	struct	ucred *b_rcred;		/* Read credentials reference. */