From: Guangliang Zhao <lucienchao@gmail.com>
Date: Tue, 1 Apr 2014 14:22:15 +0000 (+0800)
Subject: rbd: skip the copyup when an entire object writing
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=c622d226155b12276ae3d29d546f4b314d7cd68c;p=deliverable%2Flinux.git

rbd: skip the copyup when an entire object writing

It need to copyup the parent's content when layered writing,
but an entire object write would overwrite it, so skip it.

Signed-off-by: Guangliang Zhao <lucienchao@gmail.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
---

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 6dae6586a8a9..16eb247cb5fb 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2769,6 +2769,14 @@ static bool img_obj_request_simple(struct rbd_obj_request *obj_request)
 	if (!obj_request_overlaps_parent(obj_request))
 		return true;
 
+	/*
+	 * Entire-object layered writes - we will overwrite whatever
+	 * parent data there is anyway.
+	 */
+	if (!obj_request->offset &&
+	    obj_request->length == rbd_obj_bytes(&rbd_dev->header))
+		return true;
+
 	/*
 	 * If the object is known to already exist, its parent data has
 	 * already been copied.