From: Mike Snitzer snitzer@redhat.com
[ Upstream commit 0c2915b8c6db108b1dfb240391cc5a175f97f15b ]
If a DM device was suspended when bios were issued to it, those bios would be deferred using queue_io(). Once the DM device was resumed dm_process_bio() could be called by dm_wq_work() for original bio that still needs splitting. dm_process_bio()'s check for current->bio_list (meaning call chain is within ->submit_bio) as a prerequisite for calling blk_queue_split() for "abnormal IO" would result in dm_process_bio() never imposing corresponding queue_limits (e.g. discard_granularity, discard_max_bytes, etc).
Fix this by always having dm_wq_work() resubmit deferred bios using submit_bio_noacct().
Side-effect is blk_queue_split() is always called for "abnormal IO" from ->submit_bio, be it from application thread or dm_wq_work() workqueue, so proper bio splitting and depth-first bio submission is performed. For sake of clarity, remove current->bio_list check before call to blk_queue_split().
Also, remove dm_wq_work()'s use of dm_{get,put}_live_table() -- no longer needed since IO will be reissued in terms of ->submit_bio. And rename bio variable from 'c' to 'bio'.
Fixes: cf9c37865557 ("dm: fix comment in dm_process_bio()") Reported-by: Jeffle Xu jefflexu@linux.alibaba.com Reviewed-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm.c | 34 +++++++++------------------------- 1 file changed, 9 insertions(+), 25 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 6ed05ca65a0f8..b060a28ff1c6d 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1744,17 +1744,11 @@ static blk_qc_t dm_process_bio(struct mapped_device *md, }
/* - * If in ->submit_bio we need to use blk_queue_split(), otherwise - * queue_limits for abnormal requests (e.g. discard, writesame, etc) - * won't be imposed. - * If called from dm_wq_work() for deferred bio processing, bio - * was already handled by following code with previous ->submit_bio. + * Use blk_queue_split() for abnormal IO (e.g. discard, writesame, etc) + * otherwise associated queue_limits won't be imposed. */ - if (current->bio_list) { - if (is_abnormal_io(bio)) - blk_queue_split(&bio); - /* regular IO is split by __split_and_process_bio */ - } + if (is_abnormal_io(bio)) + blk_queue_split(&bio);
if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED) return __process_bio(md, map, bio, ti); @@ -2461,29 +2455,19 @@ static int dm_wait_for_completion(struct mapped_device *md, long task_state) */ static void dm_wq_work(struct work_struct *work) { - struct mapped_device *md = container_of(work, struct mapped_device, - work); - struct bio *c; - int srcu_idx; - struct dm_table *map; - - map = dm_get_live_table(md, &srcu_idx); + struct mapped_device *md = container_of(work, struct mapped_device, work); + struct bio *bio;
while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) { spin_lock_irq(&md->deferred_lock); - c = bio_list_pop(&md->deferred); + bio = bio_list_pop(&md->deferred); spin_unlock_irq(&md->deferred_lock);
- if (!c) + if (!bio) break;
- if (dm_request_based(md)) - (void) submit_bio_noacct(c); - else - (void) dm_process_bio(md, map, c); + submit_bio_noacct(bio); } - - dm_put_live_table(md, srcu_idx); }
static void dm_queue_flush(struct mapped_device *md)