- Complete part of the unfinished bufobj work by consistently using

   BO_LOCK/UNLOCK/MTX when manipulating the bufobj.
 - Create a new lock in the bufobj to lock bufobj fields independently.
   This leaves the vnode interlock as an 'identity' lock while the bufobj
   is an io lock.  The bufobj lock is ordered before the vnode interlock
   and also before the mnt ilock.
 - Exploit this new lock order to simplify softdep_check_suspend().
 - A few sync related functions are marked with a new XXX to note that
   we may not properly interlock against a non-zero bv_cnt when
   attempting to sync all vnodes on a mountlist.  I do not believe this
   race is important.  If I'm wrong this will make these locations easier
   to find.

Reviewed by:	kib (earlier diff)
Tested by:	kris, pho (earlier diff)

1 files changed, 18 insertions, 13 deletions

diff --git a/sys/kern/vfs_cluster.c b/sys/kern/vfs_cluster.c
index 7770bc4..a74c272 100644
--- a/sys/kern/vfs_cluster.c
+++ b/sys/kern/vfs_cluster.c
@@ -94,12 +94,14 @@ cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
 	struct buf **bpp;
 {
 	struct buf *bp, *rbp, *reqbp;
+	struct bufobj *bo;
 	daddr_t blkno, origblkno;
 	int maxra, racluster;
 	int error, ncontig;
 	int i;
 
 	error = 0;
+	bo = &vp->v_bufobj;
 
 	/*
 	 * Try to limit the amount of read-ahead by a few
@@ -130,7 +132,7 @@ cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
 			return 0;
 		} else {
 			bp->b_flags &= ~B_RAM;
-			VI_LOCK(vp);
+			BO_LOCK(bo);
 			for (i = 1; i < maxra; i++) {
 				/*
 				 * Stop if the buffer does not exist or it
@@ -153,7 +155,7 @@ cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
 					BUF_UNLOCK(rbp);
 				}			
 			}
-			VI_UNLOCK(vp);
+			BO_UNLOCK(bo);
 			if (i >= maxra) {
 				return 0;
 			}
@@ -305,6 +307,7 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
 	int run;
 	struct buf *fbp;
 {
+	struct bufobj *bo;
 	struct buf *bp, *tbp;
 	daddr_t bn;
 	int i, inc, j;
@@ -330,7 +333,6 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
 		tbp->b_flags |= B_ASYNC | B_RAM;
 		tbp->b_iocmd = BIO_READ;
 	}
-
 	tbp->b_blkno = blkno;
 	if( (tbp->b_flags & B_MALLOC) ||
 		((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
@@ -364,6 +366,7 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
 	bp->b_npages = 0;
 
 	inc = btodb(size);
+	bo = &vp->v_bufobj;
 	for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
 		if (i != 0) {
 			if ((bp->b_npages * PAGE_SIZE) +
@@ -384,15 +387,15 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
 			 * VMIO backed.  The clustering code can only deal
 			 * with VMIO-backed buffers.
 			 */
-			VI_LOCK(vp);
+			BO_LOCK(bo);
 			if ((tbp->b_vflags & BV_BKGRDINPROG) ||
 			    (tbp->b_flags & B_CACHE) ||
 			    (tbp->b_flags & B_VMIO) == 0) {
-				VI_UNLOCK(vp);
+				BO_UNLOCK(bo);
 				bqrelse(tbp);
 				break;
 			}
-			VI_UNLOCK(vp);
+			BO_UNLOCK(bo);
 
 			/*
 			 * The buffer must be completely invalid in order to
@@ -740,26 +743,28 @@ cluster_wbuild(vp, size, start_lbn, len)
 	int len;
 {
 	struct buf *bp, *tbp;
+	struct bufobj *bo;
 	int i, j;
 	int totalwritten = 0;
 	int dbsize = btodb(size);
 
+	bo = &vp->v_bufobj;
 	while (len > 0) {
 		/*
 		 * If the buffer is not delayed-write (i.e. dirty), or it
 		 * is delayed-write but either locked or inval, it cannot
 		 * partake in the clustered write.
 		 */
-		VI_LOCK(vp);
+		BO_LOCK(bo);
 		if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
 		    (tbp->b_vflags & BV_BKGRDINPROG)) {
-			VI_UNLOCK(vp);
+			BO_UNLOCK(bo);
 			++start_lbn;
 			--len;
 			continue;
 		}
 		if (BUF_LOCK(tbp,
-		    LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, VI_MTX(vp))) {
+		    LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_MTX(bo))) {
 			++start_lbn;
 			--len;
 			continue;
@@ -838,10 +843,10 @@ cluster_wbuild(vp, size, start_lbn, len)
 				 * If the adjacent data is not even in core it
 				 * can't need to be written.
 				 */
-				VI_LOCK(vp);
-				if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
+				BO_LOCK(bo);
+				if ((tbp = gbincore(bo, start_lbn)) == NULL ||
 				    (tbp->b_vflags & BV_BKGRDINPROG)) {
-					VI_UNLOCK(vp);
+					BO_UNLOCK(bo);
 					break;
 				}
 
@@ -854,7 +859,7 @@ cluster_wbuild(vp, size, start_lbn, len)
 				 */
 				if (BUF_LOCK(tbp,
 				    LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
-				    VI_MTX(vp)))
+				    BO_MTX(bo)))
 					break;
 
 				if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |