dm: fix missing imposition of queue_limits from dm_wq_work() thread (0c2915b8) · Commits · 戴 / test

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: ("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>

drivers/md/dm.c

+9 −25

Original line number	Diff line number	Diff line
		@@ -1676,17 +1676,11 @@ 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 (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED)
		return __process_bio(md, map, bio);
		@@ -2383,29 +2377,19 @@ 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)

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