[PATCH] blktrace: only add a bounce trace when we really bounce

Currently we issue a bounce trace when __blk_queue_bounce() is called,
but that merely means that the device has a lower dma mask than the
higher pages in the system. The bio itself may still be lower pages. So
move the bounce trace into __blk_queue_bounce(), when we know there will
actually be page bouncing.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/bounce.c b/mm/bounce.c
index e4b62d2a402495425ce1d222cdf88b4340825951..643efbe82402e2d8e1e530521e67e345896bdc26 100644 (file)
--- a/mm/bounce.c
+++ b/mm/bounce.c
@@ -237,6 +237,8 @@ static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig,
        if (!bio)
                return;
 
+       blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE);
+
        /*
         * at least one page was bounced, fill in possible non-highmem
         * pages
@@ -291,8 +293,6 @@ void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig)
                pool = isa_page_pool;
        }
 
-       blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE);
-
        /*
         * slow path
         */