From: Tang Junhui Date: Wed, 6 Sep 2017 06:25:52 +0000 (+0800) Subject: bcache: fix sequential large write IO bypass X-Git-Tag: v4.14-rc1~81^2~12 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c81ffa32a214c84b08900fbc9d432187bd948eba;p=platform%2Fkernel%2Flinux-rpi.git bcache: fix sequential large write IO bypass Sequential write IOs were tested with bs=1M by FIO in writeback cache mode, these IOs were expected to be bypassed, but actually they did not. We debug the code, and find in check_should_bypass(): if (!congested && mode == CACHE_MODE_WRITEBACK && op_is_write(bio_op(bio)) && (bio-＞bi_opf & REQ_SYNC)) goto rescale that means, If in writeback mode, a write IO with REQ_SYNC flag will not be bypassed though it is a sequential large IO, It's not a correct thing to do actually, so this patch remove these codes. Signed-off-by: tang.junhui Reviewed-by: Kent Overstreet Reviewed-by: Eric Wheeler Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe --- diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c index 0e1463d..de97d86 100644 --- a/drivers/md/bcache/request.c +++ b/drivers/md/bcache/request.c @@ -400,12 +400,6 @@ static bool check_should_bypass(struct cached_dev *dc, struct bio *bio) if (!congested && !dc->sequential_cutoff) goto rescale; - if (!congested && - mode == CACHE_MODE_WRITEBACK && - op_is_write(bio->bi_opf) && - op_is_sync(bio->bi_opf)) - goto rescale; - spin_lock(&dc->io_lock); hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash)