# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.867   -> 1.868  
#	drivers/block/ll_rw_blk.c	1.138   -> 1.139  
#	include/linux/blkdev.h	1.89    -> 1.90   
#	 drivers/scsi/scsi.h	1.34    -> 1.35   
#	drivers/scsi/aic7xxx_old.c	1.30    -> 1.31   
#	drivers/block/elevator.c	1.34    -> 1.35   
#	drivers/block/deadline-iosched.c	1.9     -> 1.10   
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/11/08	axboe@burns.home.kernel.dk	1.868
# Right now we have one type of barrier in the block layer, and that is
# used mainly for making sure that the io scheduler doesn't reorder requests
# when we don't want it to. We also need a flag to tell the io scheduler
# and low level queue that this is a barrier. So basically two needs:
# 
# o software barrier, prevents the io scheduler from reordering
# o hardware barrier, driver must prevent drive from reordering
# 
# So this patch gets rid of REQ_BARRIER and instead adds REQ_SOFTBARRIER
# and REQ_HARDBARRIER.
# --------------------------------------------
#
diff -Nru a/drivers/block/deadline-iosched.c b/drivers/block/deadline-iosched.c
--- a/drivers/block/deadline-iosched.c	Fri Nov  8 09:57:41 2002
+++ b/drivers/block/deadline-iosched.c	Fri Nov  8 09:57:41 2002
@@ -207,7 +207,7 @@
 			break;
 		}
 
-		if (__rq->flags & REQ_BARRIER)
+		if (__rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER))
 			break;
 
 		/*
@@ -413,7 +413,7 @@
 	 * flush hash on barrier insert, as not to allow merges before a
 	 * barrier.
 	 */
-	if (unlikely(rq->flags & REQ_BARRIER)) {
+	if (unlikely(rq->flags & REQ_HARDBARRIER)) {
 		DL_INVALIDATE_HASH(dd);
 		q->last_merge = NULL;
 	}
diff -Nru a/drivers/block/elevator.c b/drivers/block/elevator.c
--- a/drivers/block/elevator.c	Fri Nov  8 09:57:41 2002
+++ b/drivers/block/elevator.c	Fri Nov  8 09:57:41 2002
@@ -176,7 +176,9 @@
 	while ((entry = entry->prev) != &q->queue_head) {
 		__rq = list_entry_rq(entry);
 
-		if (__rq->flags & (REQ_BARRIER | REQ_STARTED))
+		if (__rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER))
+			break;
+		else if (__rq->flags & REQ_STARTED)
 			break;
 
 		if (!(__rq->flags & REQ_CMD))
@@ -200,7 +202,7 @@
 	/*
 	 * new merges must not precede this barrier
 	 */
-	if (rq->flags & REQ_BARRIER)
+	if (rq->flags & REQ_HARDBARRIER)
 		q->last_merge = NULL;
 	else if (!q->last_merge)
 		q->last_merge = &rq->queuelist;
diff -Nru a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
--- a/drivers/block/ll_rw_blk.c	Fri Nov  8 09:57:41 2002
+++ b/drivers/block/ll_rw_blk.c	Fri Nov  8 09:57:41 2002
@@ -644,7 +644,8 @@
 static char *rq_flags[] = {
 	"REQ_RW",
 	"REQ_RW_AHEAD",
-	"REQ_BARRIER",
+	"REQ_SOFTBARRIER",
+	"REQ_HARDBARRIER",
 	"REQ_CMD",
 	"REQ_NOMERGE",
 	"REQ_STARTED",
@@ -1392,7 +1393,7 @@
 	 * must not attempt merges on this) and that it acts as a soft
 	 * barrier
 	 */
-	rq->flags |= REQ_SPECIAL | REQ_BARRIER;
+	rq->flags |= REQ_SPECIAL | REQ_SOFTBARRIER;
 
 	rq->special = data;
 
@@ -1788,7 +1789,7 @@
 	 * REQ_BARRIER implies no merging, but lets make it explicit
 	 */
 	if (barrier)
-		req->flags |= (REQ_BARRIER | REQ_NOMERGE);
+		req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
 
 	req->errors = 0;
 	req->hard_sector = req->sector = sector;
diff -Nru a/drivers/scsi/aic7xxx_old.c b/drivers/scsi/aic7xxx_old.c
--- a/drivers/scsi/aic7xxx_old.c	Fri Nov  8 09:57:41 2002
+++ b/drivers/scsi/aic7xxx_old.c	Fri Nov  8 09:57:41 2002
@@ -2867,7 +2867,7 @@
       aic_dev->r_total++;
       ptr = aic_dev->r_bins;
     }
-    if(cmd->device->simple_tags && cmd->request->flags & REQ_BARRIER)
+    if(cmd->device->simple_tags && cmd->request->flags & REQ_HARDBARRIER)
     {
       aic_dev->barrier_total++;
       if(scb->tag_action == MSG_ORDERED_Q_TAG)
@@ -10206,7 +10206,7 @@
     /* We always force TEST_UNIT_READY to untagged */
     if (cmd->cmnd[0] != TEST_UNIT_READY && sdptr->simple_tags)
     {
-      if (req->flags & REQ_BARRIER)
+      if (req->flags & REQ_HARDBARRIER)
       {
 	if(sdptr->ordered_tags)
 	{
diff -Nru a/drivers/scsi/scsi.h b/drivers/scsi/scsi.h
--- a/drivers/scsi/scsi.h	Fri Nov  8 09:57:41 2002
+++ b/drivers/scsi/scsi.h	Fri Nov  8 09:57:41 2002
@@ -915,8 +915,8 @@
 
         if(!blk_rq_tagged(req))
                 return 0;
-    
-        if(req->flags & REQ_BARRIER)
+
+	if (req->flags & REQ_HARDBARRIER)
                 *msg++ = MSG_ORDERED_TAG;
         else
                 *msg++ = MSG_SIMPLE_TAG;
diff -Nru a/include/linux/blkdev.h b/include/linux/blkdev.h
--- a/include/linux/blkdev.h	Fri Nov  8 09:57:41 2002
+++ b/include/linux/blkdev.h	Fri Nov  8 09:57:41 2002
@@ -110,7 +110,8 @@
 enum rq_flag_bits {
 	__REQ_RW,	/* not set, read. set, write */
 	__REQ_RW_AHEAD,	/* READA */
-	__REQ_BARRIER,	/* may not be passed */
+	__REQ_SOFTBARRIER,	/* may not be passed by ioscheduler */
+	__REQ_HARDBARRIER,	/* may not be passed by drive either */
 	__REQ_CMD,	/* is a regular fs rw request */
 	__REQ_NOMERGE,	/* don't touch this for merging */
 	__REQ_STARTED,	/* drive already may have started this one */
@@ -134,7 +135,8 @@
 
 #define REQ_RW		(1 << __REQ_RW)
 #define REQ_RW_AHEAD	(1 << __REQ_RW_AHEAD)
-#define REQ_BARRIER	(1 << __REQ_BARRIER)
+#define REQ_SOFTBARRIER	(1 << __REQ_SOFTBARRIER)
+#define REQ_HARDBARRIER	(1 << __REQ_HARDBARRIER)
 #define REQ_CMD		(1 << __REQ_CMD)
 #define REQ_NOMERGE	(1 << __REQ_NOMERGE)
 #define REQ_STARTED	(1 << __REQ_STARTED)
@@ -275,9 +277,10 @@
  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
  * it already be started by driver.
  */
+#define RQ_NOMERGE_FLAGS	\
+	(REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 #define rq_mergeable(rq)	\
-	(!((rq)->flags & (REQ_NOMERGE | REQ_STARTED | REQ_BARRIER))	\
-	&& ((rq)->flags & REQ_CMD))
+	(!((rq)->flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 
 /*
  * noop, requests are automagically marked as active/inactive by I/O