From: Richard Weinberger <richard@nod.at>
Date: Wed, 28 Jan 2015 15:37:40 +0000 (+0100)
Subject: UBI: Block: Explain usage of blk_rq_map_sg()
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=832b52a15085d04039b01cec56845d3972c2f301;p=sagit-ice-cold%2Fkernel_xiaomi_msm8998.git

UBI: Block: Explain usage of blk_rq_map_sg()

Signed-off-by: Richard Weinberger <richard@nod.at>
---

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 00caf460337e..995e61c38f24 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -301,6 +301,12 @@ static void ubiblock_do_work(struct work_struct *work)
 	struct request *req = blk_mq_rq_from_pdu(pdu);
 
 	blk_mq_start_request(req);
+
+	/*
+	 * It is safe to ignore the return value of blk_rq_map_sg() because
+	 * the number of sg entries is limited to UBI_MAX_SG_COUNT
+	 * and ubi_read_sg() will check that limit.
+	 */
 	blk_rq_map_sg(req->q, req, pdu->usgl.sg);
 
 	ret = ubiblock_read(pdu);