[RFC 03/11] pmem: enable REQ_FLUSH handling

Ross Zwisler
2015-10-29T20:12:32Z

Currently the PMEM driver doesn't accept REQ_FLUSH bios. These are sent
down via blkdev_issue_flush() in response to a fsync() or msync().

When we get an msync() or fsync() it is the responsibility of the DAX code
to flush all dirty pages to media. The PMEM driver then just has issue a
wmb_pmem() in response to the REQ_FLUSH to ensure that before we return all
the flushed data has been durably stored on the media.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
drivers/nvdimm/pmem.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 0ba6a97..e1e222e 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -80,7 +80,7 @@ static void pmem_make_request(struct request_queue *q, struct bio *bio)
if (do_acct)
nd_iostat_end(bio, start);

- if (bio_data_dir(bio))
+ if (bio_data_dir(bio) || (bio->bi_rw & REQ_FLUSH))
wmb_pmem();

bio_endio(bio);
@@ -189,6 +189,7 @@ static int pmem_attach_disk(struct device *dev,
blk_queue_physical_block_size(pmem->pmem_queue, PAGE_SIZE);
blk_queue_max_hw_sectors(pmem->pmem_queue, UINT_MAX);
blk_queue_bounce_limit(pmem->pmem_queue, BLK_BOUNCE_ANY);
+ blk_queue_flush(pmem->pmem_queue, REQ_FLUSH);
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, pmem->pmem_queue);

disk = alloc_disk(0);
--
2.1.0