- Define a new flag for getblk(): GB_NOCREAT. This flag causes getblk() to

   bail out if the buffer is not already present.
 - The buffer returned by incore() is not locked and should not be sent to
   brelse().  Use getblk() with the new GB_NOCREAT flag to preserve the
   desired semantics.

3 files changed, 14 insertions, 3 deletions

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index bea2269..021458c 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -2537,6 +2537,14 @@ loop:
 		 * buffer is also considered valid (not marked B_INVAL).
 		 */
 		VI_UNLOCK(vp);
+		/*
+		 * If the user does not want us to create the buffer, bail out
+		 * here.
+		 */
+		if (flags & GB_NOCREAT) {
+			splx(s);
+			return NULL;
+		}
 		if (vn_isdisk(vp, NULL))
 			bsize = DEV_BSIZE;
 		else if (vp->v_mountedhere)
diff --git a/sys/sys/buf.h b/sys/sys/buf.h
index 3965764..78ef55b 100644
--- a/sys/sys/buf.h
+++ b/sys/sys/buf.h
@@ -461,6 +461,7 @@ buf_countdeps(struct buf *bp, int i)
  * Flags for getblk's last parameter.
  */
 #define	GB_LOCK_NOWAIT	0x0001		/* Fail if we block on a buf lock. */
+#define	GB_NOCREAT	0x0002		/* Don't create a buf if not found. */
 
 #ifdef _KERNEL
 extern int	nbuf;			/* The number of buffer headers */
diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
index 429f98f..6ea776a 100644
--- a/sys/ufs/ffs/ffs_softdep.c
+++ b/sys/ufs/ffs/ffs_softdep.c
@@ -2563,10 +2563,10 @@ indir_trunc(freeblks, dbn, level, lbn, countp)
 	 * a complete copy of the indirect block in memory for our use.
 	 * Otherwise we have to read the blocks in from the disk.
 	 */
+	bp = getblk(freeblks->fb_devvp, dbn, (int)fs->fs_bsize, 0, 0,
+	    GB_NOCREAT);
 	ACQUIRE_LOCK(&lk);
-	/* XXX Buf not locked! */
-	if ((bp = incore(freeblks->fb_devvp, dbn)) != NULL &&
-	    (wk = LIST_FIRST(&bp->b_dep)) != NULL) {
+	if (bp != NULL && (wk = LIST_FIRST(&bp->b_dep)) != NULL) {
 		if (wk->wk_type != D_INDIRDEP ||
 		    (indirdep = WK_INDIRDEP(wk))->ir_savebp != bp ||
 		    (indirdep->ir_state & GOINGAWAY) == 0) {
@@ -2582,6 +2582,8 @@ indir_trunc(freeblks, dbn, level, lbn, countp)
 		VFSTOUFS(freeblks->fb_mnt)->um_numindirdeps -= 1;
 		FREE_LOCK(&lk);
 	} else {
+		if (bp)
+			brelse(bp);
 		FREE_LOCK(&lk);
 		error = bread(freeblks->fb_devvp, dbn, (int)fs->fs_bsize,
 		    NOCRED, &bp);