From: Matthew Dillon <dillon@dragonflybsd.org>
Date: Sun, 30 Apr 2006 18:52:37 +0000 (+0000)
Subject: The pbuf subsystem now initializes b_kvabase and b_kvasize at startup and
X-Git-Tag: v2.0.1~5008
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/312dcd01e39b41c5e63bb9e2082a3531a1ac693b

The pbuf subsystem now initializes b_kvabase and b_kvasize at startup and
no longer reinitializes these fields in initpbuf().

Users of getpbuf() may no longer modify b_kvabase or b_kvasize.  b_data may
still be modified.
---

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index e2e3c74d16..3ac6febdf0 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -12,7 +12,7 @@
  *		John S. Dyson.
  *
  * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $
- * $DragonFly: src/sys/kern/vfs_bio.c,v 1.68 2006/04/30 18:25:35 dillon Exp $
+ * $DragonFly: src/sys/kern/vfs_bio.c,v 1.69 2006/04/30 18:52:36 dillon Exp $
  */
 
 /*
@@ -519,7 +519,7 @@ clearbiocache(struct bio *bio)
  *	Since this call frees up buffer space, we call bufspacewakeup().
  */
 static void
-bfreekva(struct buf * bp)
+bfreekva(struct buf *bp)
 {
 	int count;
 
@@ -2429,7 +2429,7 @@ allocbuf(struct buf *bp, int size)
 
 		if (newbsize < bp->b_bufsize) {
 			/*
-			 * malloced buffers are not shrunk
+			 * Malloced buffers are not shrunk
 			 */
 			if (bp->b_flags & B_MALLOC) {
 				if (newbsize) {
diff --git a/sys/kern/vfs_cluster.c b/sys/kern/vfs_cluster.c
index 1a32a8080b..1d980e9a81 100644
--- a/sys/kern/vfs_cluster.c
+++ b/sys/kern/vfs_cluster.c
@@ -34,7 +34,7 @@
  *
  *	@(#)vfs_cluster.c	8.7 (Berkeley) 2/13/94
  * $FreeBSD: src/sys/kern/vfs_cluster.c,v 1.92.2.9 2001/11/18 07:10:59 dillon Exp $
- * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.22 2006/04/30 17:22:17 dillon Exp $
+ * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.23 2006/04/30 18:52:36 dillon Exp $
  */
 
 #include "opt_debug_cluster.h"
@@ -484,10 +484,10 @@ cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset,
 			bp->b_xio.xio_pages[j] = bogus_page;
 		}
 	}
-	if (bp->b_bufsize > bp->b_kvasize)
+	if (bp->b_bufsize > bp->b_kvasize) {
 		panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
 		    bp->b_bufsize, bp->b_kvasize);
-	bp->b_kvasize = bp->b_bufsize;
+	}
 
 	pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 		(vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
@@ -922,11 +922,11 @@ cluster_wbuild(struct vnode *vp, int size, off_t start_loffset, int bytes)
 	finishcluster:
 		pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 			(vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
-		if (bp->b_bufsize > bp->b_kvasize)
+		if (bp->b_bufsize > bp->b_kvasize) {
 			panic(
 			    "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
 			    bp->b_bufsize, bp->b_kvasize);
-		bp->b_kvasize = bp->b_bufsize;
+		}
 		totalwritten += bp->b_bufsize;
 		bp->b_dirtyoff = 0;
 		bp->b_dirtyend = bp->b_bufsize;
diff --git a/sys/vm/vm_pager.c b/sys/vm/vm_pager.c
index 1b75ba656e..0a4518a467 100644
--- a/sys/vm/vm_pager.c
+++ b/sys/vm/vm_pager.c
@@ -62,7 +62,7 @@
  * rights to redistribute these changes.
  *
  * $FreeBSD: src/sys/vm/vm_pager.c,v 1.54.2.2 2001/11/18 07:11:00 dillon Exp $
- * $DragonFly: src/sys/vm/vm_pager.c,v 1.20 2006/04/30 18:25:37 dillon Exp $
+ * $DragonFly: src/sys/vm/vm_pager.c,v 1.21 2006/04/30 18:52:37 dillon Exp $
  */
 
 /*
@@ -205,21 +205,29 @@ vm_pager_bufferinit(void)
 	struct buf *bp;
 	int i;
 
-	bp = swbuf;
 	/*
-	 * Now set up swap and physical I/O buffer headers.
+	 * Reserve KVM space for pbuf data.
+	 */
+	swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS);
+	if (!swapbkva)
+		panic("Not enough pager_map VM space for physical buffers");
+
+	/*
+	 * Initial pbuf setup.
 	 */
-	for (i = 0; i < nswbuf; i++, bp++) {
+	bp = swbuf;
+	for (i = 0; i < nswbuf; ++i, ++bp) {
+		bp->b_kvabase = (caddr_t)(i * MAXPHYS) + swapbkva;
+		bp->b_kvasize = MAXPHYS;
 		TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
 		BUF_LOCKINIT(bp);
 		LIST_INIT(&bp->b_dep);
 	}
 
+	/*
+	 * Allow the clustering code to use half of our pbufs.
+	 */
 	cluster_pbuf_freecnt = nswbuf / 2;
-
-	swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS);
-	if (!swapbkva)
-		panic("Not enough pager_map VM space for physical buffers");
 }
 
 /*
@@ -307,16 +315,13 @@ vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
 }
 
 /*
- * initialize a physical buffer
+ * Initialize a physical buffer.
  */
-
 static void
 initpbuf(struct buf *bp)
 {
 	bp->b_qindex = 0; /* BQUEUE_NONE */
-	bp->b_data = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva;
-	bp->b_kvabase = bp->b_data;
-	bp->b_kvasize = MAXPHYS;
+	bp->b_data = bp->b_kvabase;
 	bp->b_flags = B_PAGING;
 	bp->b_cmd = BUF_CMD_DONE;
 	bp->b_error = 0;