1 files changed, 89 insertions, 0 deletions
diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c
index f629b19..feecc3d 100644
--- a/sys/kern/vfs_default.c
+++ b/sys/kern/vfs_default.c
@@ -708,6 +708,95 @@ vop_stdbmap(ap)
 	return (0);
 }
 
+int
+vop_stdfsync(ap)
+	struct vop_fsync_args /* {
+		struct vnode *a_vp;
+		struct ucred *a_cred;
+		int a_waitfor;
+		struct thread *a_td;
+	} */ *ap;
+{
+	struct vnode *vp = ap->a_vp;
+	struct buf *bp;
+	struct buf *nbp;
+	int s, error = 0;
+	int maxretry = 100;     /* large, arbitrarily chosen */
+
+	VI_LOCK(vp);
+loop1:
+	/*
+	 * MARK/SCAN initialization to avoid infinite loops.
+	 */
+	s = splbio();
+        TAILQ_FOREACH(bp, &vp->v_dirtyblkhd, b_vnbufs) {
+                bp->b_vflags &= ~BV_SCANNED;
+		bp->b_error = 0;
+	}
+	splx(s);
+
+	/*
+	 * Flush all dirty buffers associated with a block device.
+	 */
+loop2:
+	s = splbio();
+	for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp != NULL; bp = nbp) {
+		nbp = TAILQ_NEXT(bp, b_vnbufs);
+		if ((bp->b_vflags & BV_SCANNED) != 0)
+			continue;
+		bp->b_vflags |= BV_SCANNED;
+		if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT))
+			continue;
+		VI_UNLOCK(vp);
+		if ((bp->b_flags & B_DELWRI) == 0)
+			panic("spec_fsync: not dirty");
+		if ((vp->v_vflag & VV_OBJBUF) && (bp->b_flags & B_CLUSTEROK)) {
+			BUF_UNLOCK(bp);
+			vfs_bio_awrite(bp);
+			splx(s);
+		} else {
+			bremfree(bp);
+			splx(s);
+			bawrite(bp);
+		}
+		VI_LOCK(vp);
+		goto loop2;
+	}
+
+	/*
+	 * If synchronous the caller expects us to completely resolve all
+	 * dirty buffers in the system.  Wait for in-progress I/O to
+	 * complete (which could include background bitmap writes), then
+	 * retry if dirty blocks still exist.
+	 */
+	if (ap->a_waitfor == MNT_WAIT) {
+		while (vp->v_numoutput) {
+			vp->v_iflag |= VI_BWAIT;
+			msleep((caddr_t)&vp->v_numoutput, VI_MTX(vp),
+			    PRIBIO + 1, "spfsyn", 0);
+		}
+		if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
+			/*
+			 * If we are unable to write any of these buffers
+			 * then we fail now rather than trying endlessly
+			 * to write them out.
+			 */
+			TAILQ_FOREACH(bp, &vp->v_dirtyblkhd, b_vnbufs)
+				if ((error = bp->b_error) == 0)
+					continue;
+			if (error == 0 && --maxretry >= 0) {
+				splx(s);
+				goto loop1;
+			}
+			vprint("fsync: giving up on dirty", vp);
+			error = EAGAIN;
+		}
+	}
+	VI_UNLOCK(vp);
+	splx(s);
+	
+	return (error);
+}
 /* XXX Needs good comment and more info in the manpage (VOP_GETPAGES(9)). */
 int
 vop_stdgetpages(ap)