- Introduce the function lockmgr_recursed() which returns true if the

  lockmgr lkp, when held in exclusive mode, is recursed
- Introduce the function BUF_RECURSED() which does the same for bufobj
  locks based on the top of lockmgr_recursed()
- Introduce the function BUF_ISLOCKED() which works like the counterpart
  VOP_ISLOCKED(9), showing the state of lockmgr linked with the bufobj

BUF_RECURSED() and BUF_ISLOCKED() entirely replace the usage of bogus
BUF_REFCNT() in a more explicative and SMP-compliant way.
This allows us to axe out BUF_REFCNT() and leaving the function
lockcount() totally unused in our stock kernel. Further commits will
axe lockcount() as well as part of lockmgr() cleanup.

KPI results, obviously, broken so further commits will update manpages
and freebsd version.

Tested by: kris (on UFS and NFS)

3 files changed, 16 insertions, 18 deletions

diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c
index 7bbd98f..c3de8c1f 100644
--- a/sys/kern/kern_shutdown.c
+++ b/sys/kern/kern_shutdown.c
@@ -255,7 +255,7 @@ static int
 isbufbusy(struct buf *bp)
 {
 	if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 &&
-	    BUF_REFCNT(bp) > 0) ||
+	    BUF_ISLOCKED(bp)) ||
 	    ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
 		return (1);
 	return (0);
diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index e0f395a..8c6cd8a 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -658,7 +658,7 @@ bremfree(struct buf *bp)
 {
 
 	CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
-	KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked."));
+	KASSERT(BUF_ISLOCKED(bp), ("bremfree: buf must be locked."));
 	KASSERT((bp->b_flags & B_REMFREE) == 0,
 	    ("bremfree: buffer %p already marked for delayed removal.", bp));
 	KASSERT(bp->b_qindex != QUEUE_NONE,
@@ -695,7 +695,7 @@ bremfreel(struct buf *bp)
 {
 	CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
 	    bp, bp->b_vp, bp->b_flags);
-	KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp));
+	KASSERT(BUF_ISLOCKED(bp), ("bremfreel: buffer %p not locked.", bp));
 	KASSERT(bp->b_qindex != QUEUE_NONE,
 	    ("bremfreel: buffer %p not on a queue.", bp));
 	mtx_assert(&bqlock, MA_OWNED);
@@ -834,7 +834,7 @@ bufwrite(struct buf *bp)
 
 	oldflags = bp->b_flags;
 
-	if (BUF_REFCNT(bp) == 0)
+	if (!BUF_ISLOCKED(bp))
 		panic("bufwrite: buffer is not busy???");
 
 	if (bp->b_pin_count > 0)
@@ -952,7 +952,7 @@ bdwrite(struct buf *bp)
 
 	CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
 	KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
-	KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy"));
+	KASSERT(BUF_ISLOCKED(bp), ("bdwrite: buffer is not busy"));
 
 	if (bp->b_flags & B_INVAL) {
 		brelse(bp);
@@ -1047,7 +1047,7 @@ bdirty(struct buf *bp)
 
 	CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
 	    bp, bp->b_vp, bp->b_flags);
-	KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp));
+	KASSERT(BUF_ISLOCKED(bp), ("bdirty: bp %p not locked",bp));
 	KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
 	KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
 	    ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
@@ -1081,7 +1081,7 @@ bundirty(struct buf *bp)
 	KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
 	KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
 	    ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
-	KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp));
+	KASSERT(BUF_ISLOCKED(bp), ("bundirty: bp %p not locked",bp));
 
 	if (bp->b_flags & B_DELWRI) {
 		bp->b_flags &= ~B_DELWRI;
@@ -1341,7 +1341,7 @@ brelse(struct buf *bp)
 			brelvp(bp);
 	}
 			
-	if (BUF_REFCNT(bp) > 1) {
+	if (BUF_LOCKRECURSED(bp)) {
 		/* do not release to free list */
 		BUF_UNLOCK(bp);
 		return;
@@ -1446,7 +1446,7 @@ bqrelse(struct buf *bp)
 	KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
 	    ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
 
-	if (BUF_REFCNT(bp) > 1) {
+	if (BUF_LOCKRECURSED(bp)) {
 		/* do not release to free list */
 		BUF_UNLOCK(bp);
 		return;
@@ -2660,7 +2660,7 @@ loop:
 		bp->b_flags &= ~B_DONE;
 	}
 	CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
-	KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
+	KASSERT(BUF_ISLOCKED(bp), ("getblk: bp %p not locked",bp));
 	KASSERT(bp->b_bufobj == bo,
 	    ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 	return (bp);
@@ -2681,7 +2681,7 @@ geteblk(int size)
 		continue;
 	allocbuf(bp, size);
 	bp->b_flags |= B_INVAL;	/* b_dep cleared by getnewbuf() */
-	KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
+	KASSERT(BUF_ISLOCKED(bp), ("geteblk: bp %p not locked",bp));
 	return (bp);
 }
 
@@ -2707,7 +2707,7 @@ allocbuf(struct buf *bp, int size)
 	int newbsize, mbsize;
 	int i;
 
-	if (BUF_REFCNT(bp) == 0)
+	if (!BUF_ISLOCKED(bp))
 		panic("allocbuf: buffer not busy");
 
 	if (bp->b_kvasize < size)
@@ -3150,8 +3150,7 @@ bufdone(struct buf *bp)
 	CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
 	dropobj = NULL;
 
-	KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp,
-	    BUF_REFCNT(bp)));
+	KASSERT(BUF_ISLOCKED(bp), ("biodone: bp %p not busy", bp));
 	KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
 
 	runningbufwakeup(bp);
@@ -3176,8 +3175,7 @@ bufdone(struct buf *bp)
 void
 bufdone_finish(struct buf *bp)
 {
-	KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp,
-	    BUF_REFCNT(bp)));
+	KASSERT(BUF_ISLOCKED(bp), ("biodone: bp %p not busy", bp));
 
 	if (!LIST_EMPTY(&bp->b_dep))
 		buf_complete(bp);
@@ -3943,7 +3941,7 @@ DB_SHOW_COMMAND(lockedbufs, lockedbufs)
 
 	for (i = 0; i < nbuf; i++) {
 		bp = &buf[i];
-		if (lockcount(&bp->b_lock)) {
+		if (BUF_ISLOCKED(bp)) {
 			db_show_buffer((uintptr_t)bp, 1, 0, NULL);
 			db_printf("\n");
 		}
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 953c1d8..2fe63b0 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -3570,7 +3570,7 @@ vop_strategy_pre(void *ap)
 	if ((bp->b_flags & B_CLUSTER) != 0)
 		return;
 
-	if (BUF_REFCNT(bp) < 1) {
+	if (!BUF_ISLOCKED(bp)) {
 		if (vfs_badlock_print)
 			printf(
 			    "VOP_STRATEGY: bp is not locked but should be\n");