block, drivers, fs: rename REQ_FLUSH to REQ_PREFLUSH

To avoid confusion between REQ_OP_FLUSH, which is handled by
request_fn drivers, and upper layers requesting the block layer
perform a flush sequence along with possibly a WRITE, this patch
renames REQ_FLUSH to REQ_PREFLUSH.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

kernel/trace/blktrace.c

@@ -189,6 +189,7 @@ static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 				 BLK_TC_ACT(BLK_TC_WRITE) };
 
 #define BLK_TC_RAHEAD		BLK_TC_AHEAD
+#define BLK_TC_PREFLUSH		BLK_TC_FLUSH
 
 /* The ilog2() calls fall out because they're constant */
 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
@@ -219,7 +220,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	what |= MASK_TC_BIT(op_flags, SYNC);
 	what |= MASK_TC_BIT(op_flags, RAHEAD);
 	what |= MASK_TC_BIT(op_flags, META);
-	what |= MASK_TC_BIT(op_flags, FLUSH);
+	what |= MASK_TC_BIT(op_flags, PREFLUSH);
 	what |= MASK_TC_BIT(op_flags, FUA);
 	if (op == REQ_OP_DISCARD)
 		what |= BLK_TC_ACT(BLK_TC_DISCARD);
@@ -1779,7 +1780,7 @@ void blk_fill_rwbs(char *rwbs, int op, u32 rw, int bytes)
 {
 	int i = 0;
 
-	if (rw & REQ_FLUSH)
+	if (rw & REQ_PREFLUSH)
 		rwbs[i++] = 'F';
 
 	switch (op) {