From 566c0d6a74169dc5cc9f353ff4a8d579d96a85ff Mon Sep 17 00:00:00 2001 From: Roman Peniaev Date: Sat, 8 Mar 2014 21:59:14 +0900 Subject: [PATCH] mtd: mtd_blkdevs: handle REQ_FLUSH request and do explicit flush of writeback buffer mtd_blkdevs is device with volatile cache (writeback buffer), so it should support REQ_FLUSH to do explicit flush. Without this patch 'sync' does not guarantee that writeback buffer will be flushed on disk in case of power off, e.g.: $ cp some_file /mnt $ sync ### POWER OFF In case of this sequence writeback buffer will not be flushed on disk. This patch fixes this behaviour and explicitly reports to block layer that flush requests are being supported. Signed-off-by: Roman Peniaev Cc: David Woodhouse Cc: linux-mtd@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Brian Norris --- drivers/mtd/mtd_blkdevs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 0b2ccb68c0d0..d2f0da91a5bd 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -88,6 +88,9 @@ static int do_blktrans_request(struct mtd_blktrans_ops *tr, if (req->cmd_type != REQ_TYPE_FS) return -EIO; + if (req->cmd_flags & REQ_FLUSH) + return tr->flush(dev); + if (blk_rq_pos(req) + blk_rq_cur_sectors(req) > get_capacity(req->rq_disk)) return -EIO; @@ -408,6 +411,9 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) if (!new->rq) goto error3; + if (tr->flush) + blk_queue_flush(new->rq, REQ_FLUSH); + new->rq->queuedata = new; blk_queue_logical_block_size(new->rq, tr->blksize);