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mtd: mtd_blkdevs: handle REQ_FLUSH request and do explicit flush of writeback buffer

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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 <r.peniaev@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: linux-mtd@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This commit is contained in:
Roman Peniaev 2014-03-08 21:59:14 +09:00 committed by Brian Norris
parent 47570bb1f5
commit 566c0d6a74
1 changed files with 6 additions and 0 deletions
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6
drivers/mtd/mtd_blkdevs.c
View file

@ -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);