- Add a new 'flags' parameter to getblk().

 - Define one flag GB_LOCK_NOWAIT that tells getblk() to pass the LK_NOWAIT
   flag to the initial BUF_LOCK().  This will eventually be used in cases
   were we want to use a buffer only if it is not currently in use.
 - Convert all consumers of the getblk() api to use this extra parameter.

Reviwed by:	arch
Not objected to by:	mckusick

2 files changed, 14 insertions, 9 deletions

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 10ad7dc..a2807e9 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -680,7 +680,7 @@ breadn(struct vnode * vp, daddr_t blkno, int size,
 	int i;
 	int rv = 0, readwait = 0;
 
-	*bpp = bp = getblk(vp, blkno, size, 0, 0);
+	*bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
 
 	/* if not found in cache, do some I/O */
 	if ((bp->b_flags & B_CACHE) == 0) {
@@ -702,7 +702,7 @@ breadn(struct vnode * vp, daddr_t blkno, int size,
 	for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
 		if (inmem(vp, *rablkno))
 			continue;
-		rabp = getblk(vp, *rablkno, *rabsize, 0, 0);
+		rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
 
 		if ((rabp->b_flags & B_CACHE) == 0) {
 			if (curthread != PCPU_GET(idlethread))
@@ -2367,7 +2367,8 @@ vfs_setdirty(struct buf *bp)
  *	prior to issuing the READ.  biodone() will *not* clear B_INVAL.
  */
 struct buf *
-getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
+getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
+    int flags)
 {
 	struct buf *bp;
 	int s;
@@ -2399,13 +2400,17 @@ loop:
 
 	VI_LOCK(vp);
 	if ((bp = gbincore(vp, blkno))) {
+		int lockflags;
 		/*
 		 * Buffer is in-core.  If the buffer is not busy, it must
 		 * be on a queue.
 		 */
+		lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
 
-		error = BUF_TIMELOCK(bp,
-		    LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
+		if (flags & GB_LOCK_NOWAIT)
+			lockflags |= LK_NOWAIT;
+
+		error = BUF_TIMELOCK(bp, lockflags,
 		    VI_MTX(vp), "getblk", slpflag, slptimeo);
 
 		/*
diff --git a/sys/kern/vfs_cluster.c b/sys/kern/vfs_cluster.c
index 96e541c..bf944c5 100644
--- a/sys/kern/vfs_cluster.c
+++ b/sys/kern/vfs_cluster.c
@@ -125,7 +125,7 @@ cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
 	/*
 	 * get the requested block
 	 */
-	*bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0);
+	*bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, 0);
 	origblkno = lblkno;
 	origtotread = totread;
 
@@ -243,7 +243,7 @@ single_block_read:
 				rbp = cluster_rbuild(vp, filesize, lblkno,
 					blkno, size, ntoread, NULL);
 			} else {
-				rbp = getblk(vp, lblkno, size, 0, 0);
+				rbp = getblk(vp, lblkno, size, 0, 0, 0);
 				rbp->b_flags |= B_ASYNC | B_RAM;
 				rbp->b_iocmd = BIO_READ;
 				rbp->b_blkno = blkno;
@@ -349,7 +349,7 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
 		tbp = fbp;
 		tbp->b_iocmd = BIO_READ; 
 	} else {
-		tbp = getblk(vp, lbn, size, 0, 0);
+		tbp = getblk(vp, lbn, size, 0, 0, 0);
 		if (tbp->b_flags & B_CACHE)
 			return tbp;
 		tbp->b_flags |= B_ASYNC | B_RAM;
@@ -420,7 +420,7 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
 					break;
 			}
 
-			tbp = getblk(vp, lbn + i, size, 0, 0);
+			tbp = getblk(vp, lbn + i, size, 0, 0, 0);
 
 			/*
 			 * Stop scanning if the buffer is fully valid