On Wed, May 31, 2017 at 09:44:33AM +0200, Jan Kara wrote:
> Commit b685d3d65ac7 "block: treat REQ_FUA and REQ_PREFLUSH as
> synchronous" removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...}
> definitions. generic_make_request_checks() however strips REQ_FUA and
> REQ_PREFLUSH flags from a bio when the storage doesn't report volatile
> write cache and thus write effectively becomes asynchronous which can
> lead to performance regressions
>
> Fix the problem by making sure all bios which are synchronous are
> properly marked with REQ_SYNC.
Applied, thanks!
> CC: linux-raid@xxxxxxxxxxxxxxx
> CC: Shaohua Li <shli@xxxxxxxxxx>
> Fixes: b685d3d65ac791406e0dfd8779cc9b3707fea5a3
> CC: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> drivers/md/md.c | 2 +-
> drivers/md/raid5-cache.c | 4 ++--
> drivers/md/raid5-ppl.c | 4 ++--
> 3 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 10367ffe92e3..212a6777ff31 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -765,7 +765,7 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
> test_bit(FailFast, &rdev->flags) &&
> !test_bit(LastDev, &rdev->flags))
> ff = MD_FAILFAST;
> - bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_FUA | ff;
> + bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH | REQ_FUA | ff;
>
> atomic_inc(&mddev->pending_writes);
> submit_bio(bio);
> diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
> index 4c00bc248287..0a7af8b0a80a 100644
> --- a/drivers/md/raid5-cache.c
> +++ b/drivers/md/raid5-cache.c
> @@ -1782,7 +1782,7 @@ static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos,
> mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,
> mb, PAGE_SIZE));
> if (!sync_page_io(log->rdev, pos, PAGE_SIZE, page, REQ_OP_WRITE,
> - REQ_FUA, false)) {
> + REQ_SYNC | REQ_FUA, false)) {
> __free_page(page);
> return -EIO;
> }
> @@ -2388,7 +2388,7 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
> mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,
> mb, PAGE_SIZE));
> sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page,
> - REQ_OP_WRITE, REQ_FUA, false);
> + REQ_OP_WRITE, REQ_SYNC | REQ_FUA, false);
> sh->log_start = ctx->pos;
> list_add_tail(&sh->r5c, &log->stripe_in_journal_list);
> atomic_inc(&log->stripe_in_journal_count);
> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
> index 5d25bebf3328..ccce92e68d7f 100644
> --- a/drivers/md/raid5-ppl.c
> +++ b/drivers/md/raid5-ppl.c
> @@ -907,8 +907,8 @@ static int ppl_write_empty_header(struct ppl_log *log)
> pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
>
> if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
> - PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_FUA, 0,
> - false)) {
> + PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_SYNC |
> + REQ_FUA, 0, false)) {
> md_error(rdev->mddev, rdev);
> ret = -EIO;
> }
> --
> 2.12.3
>