- Handle buffer lock waiters count directly in the buffer cache instead

  than rely on the lockmgr support [1]:
  * bump the waiters only if the interlock is held
  * let brelvp() return the waiters count
  * rely on brelvp() instead than BUF_LOCKWAITERS() in order to check
    for the waiters number
- Remove a namespace pollution introduced recently with lockmgr.h
  including lock.h by including lock.h directly in the consumers and
  making it mandatory for using lockmgr.
- Modify flags accepted by lockinit():
  * introduce LK_NOPROFILE which disables lock profiling for the
    specified lockmgr
  * introduce LK_QUIET which disables ktr tracing for the specified
    lockmgr [2]
  * disallow LK_SLEEPFAIL and LK_NOWAIT to be passed there so that it
    can only be used on a per-instance basis
- Remove BUF_LOCKWAITERS() and lockwaiters() as they are no longer
  used

This patch breaks KPI so __FreBSD_version will be bumped and manpages
updated by further commits. Additively, 'struct buf' changes results in
a disturbed ABI also.

[2] Really, currently there is no ktr tracing in the lockmgr, but it
will be added soon.

[1] Submitted by:	kib
Tested by:	pho, Andrea Barberio <insomniac at slackware dot it>

1 files changed, 8 insertions, 6 deletions

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index b789149..cf0ea46 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -557,6 +557,7 @@ bufinit(void)
 		bp->b_qindex = QUEUE_EMPTY;
 		bp->b_vflags = 0;
 		bp->b_xflags = 0;
+		bp->b_waiters = 0;
 		LIST_INIT(&bp->b_dep);
 		BUF_LOCKINIT(bp);
 		TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
@@ -1195,7 +1196,7 @@ brelse(struct buf *bp)
 			if (bp->b_bufsize)
 				allocbuf(bp, 0);
 			if (bp->b_vp)
-				brelvp(bp);
+				(void) brelvp(bp);
 		}
 	}
 
@@ -1337,7 +1338,7 @@ brelse(struct buf *bp)
 		if (bp->b_bufsize != 0)
 			allocbuf(bp, 0);
 		if (bp->b_vp != NULL)
-			brelvp(bp);
+			(void) brelvp(bp);
 	}
 			
 	if (BUF_LOCKRECURSED(bp)) {
@@ -1401,7 +1402,7 @@ brelse(struct buf *bp)
 		if (bp->b_flags & B_DELWRI)
 			bundirty(bp);
 		if (bp->b_vp)
-			brelvp(bp);
+			(void) brelvp(bp);
 	}
 
 	/*
@@ -1569,7 +1570,7 @@ vfs_vmio_release(struct buf *bp)
 	bp->b_npages = 0;
 	bp->b_flags &= ~B_VMIO;
 	if (bp->b_vp)
-		brelvp(bp);
+		(void) brelvp(bp);
 }
 
 /*
@@ -1706,6 +1707,7 @@ getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
 	struct buf *nbp;
 	int defrag = 0;
 	int nqindex;
+	int waiters = 0;
 	static int flushingbufs;
 
 	/*
@@ -1844,7 +1846,7 @@ restart:
 				vfs_vmio_release(bp);
 			}
 			if (bp->b_vp)
-				brelvp(bp);
+				waiters = brelvp(bp);
 		}
 
 		/*
@@ -1913,7 +1915,7 @@ restart:
 		 * Notify any waiters for the buffer lock about
 		 * identity change by freeing the buffer.
 		 */
-		if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) {
+		if (qindex == QUEUE_CLEAN && waiters > 0) {
 			bp->b_flags |= B_INVAL;
 			bfreekva(bp);
 			brelse(bp);