[Midnightbsd-cvs] src [9140] trunk/sys/kern/vfs_bio.c: add babarrierwrite

[laffer1 at midnightbsd.org]

Revision: 9140
          http://svnweb.midnightbsd.org/src/?rev=9140
Author:   laffer1
Date:     2016-10-01 22:21:12 -0400 (Sat, 01 Oct 2016)
Log Message:
-----------
add babarrierwrite

Modified Paths:
--------------
    trunk/sys/kern/vfs_bio.c

Modified: trunk/sys/kern/vfs_bio.c
===================================================================
--- trunk/sys/kern/vfs_bio.c	2016-10-02 02:20:26 UTC (rev 9139)
+++ trunk/sys/kern/vfs_bio.c	2016-10-02 02:21:12 UTC (rev 9140)
@@ -206,6 +206,9 @@
 static long notbufdflashes;
 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, &notbufdflashes, 0,
     "Number of dirty buffer flushes done by the bufdaemon helpers");
+static long barrierwrites;
+SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
+    "Number of barrier writes");
 
 /*
  * Wakeup point for bufdaemon, as well as indicator of whether it is already
@@ -914,6 +917,9 @@
 		return (0);
 	}
 
+	if (bp->b_flags & B_BARRIER)
+		barrierwrites++;
+
 	oldflags = bp->b_flags;
 
 	BUF_ASSERT_HELD(bp);
@@ -1038,6 +1044,8 @@
 
 	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((bp->b_flags & B_BARRIER) == 0,
+	    ("Barrier request in delayed write %p", bp));
 	BUF_ASSERT_HELD(bp);
 
 	if (bp->b_flags & B_INVAL) {
@@ -1198,6 +1206,40 @@
 }
 
 /*
+ *	babarrierwrite:
+ *
+ *	Asynchronous barrier write.  Start output on a buffer, but do not
+ *	wait for it to complete.  Place a write barrier after this write so
+ *	that this buffer and all buffers written before it are committed to
+ *	the disk before any buffers written after this write are committed
+ *	to the disk.  The buffer is released when the output completes.
+ */
+void
+babarrierwrite(struct buf *bp)
+{
+
+	bp->b_flags |= B_ASYNC | B_BARRIER;
+	(void) bwrite(bp);
+}
+
+/*
+ *	bbarrierwrite:
+ *
+ *	Synchronous barrier write.  Start output on a buffer and wait for
+ *	it to complete.  Place a write barrier after this write so that
+ *	this buffer and all buffers written before it are committed to 
+ *	the disk before any buffers written after this write are committed
+ *	to the disk.  The buffer is released when the output completes.
+ */
+int
+bbarrierwrite(struct buf *bp)
+{
+
+	bp->b_flags |= B_BARRIER;
+	return (bwrite(bp));
+}
+
+/*
  *	bwillwrite:
  *
  *	Called prior to the locking of any vnodes when we are expecting to