From: Roman Peniaev <[email protected]>
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 <[email protected]>
CC: David Woodhouse <[email protected]>
CC: [email protected]
CC: [email protected]
---
drivers/mtd/mtd_blkdevs.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 5073cbc..feafe5c 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -89,6 +89,12 @@ 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) {
+ if (tr->flush)
+ return tr->flush(dev);
+ return 0;
+ }
+
if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
get_capacity(req->rq_disk))
return -EIO;
@@ -409,6 +415,8 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
if (!new->rq)
goto error3;
+ blk_queue_flush(new->rq, REQ_FLUSH);
+
new->rq->queuedata = new;
blk_queue_logical_block_size(new->rq, tr->blksize);
--
1.8.5.2