Commit 03100aad authored by Keith Busch's avatar Keith Busch Committed by Jens Axboe
Browse files

block: Replace SG_GAPS with new queue limits mask 



The SG_GAPS queue flag caused checks for bio vector alignment against
PAGE_SIZE, but the device may have different constraints. This patch
adds a queue limits so a driver with such constraints can set to allow
requests that would have been unnecessarily split. The new gaps check
takes the request_queue as a parameter to simplify the logic around
invoking this function.

This new limit makes the queue flag redundant, so removing it and
all usage. Device-mappers will inherit the correct settings through
blk_stack_limits().

Signed-off-by: default avatarKeith Busch <keith.busch@intel.com>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent d2be537c

block/bio.c

+1 −2
Original line number Diff line number Diff line
@@ -742,8 +742,7 @@ int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page 
		 * If the queue doesn't support SG gaps and adding this

		 * offset would create a gap, disallow it.

		 */

		if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS) &&

		    bvec_gap_to_prev(prev, offset))

		if (bvec_gap_to_prev(q, prev, offset))

			return 0;

	}

block/blk-merge.c

+7 −16
Original line number Diff line number Diff line
@@ -82,8 +82,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, 
		 * If the queue doesn't support SG gaps and adding this

		 * offset would create a gap, disallow it.

		 */

		if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS) &&

		    prev && bvec_gap_to_prev(&bvprv, bv.bv_offset))

		if (prev && bvec_gap_to_prev(q, &bvprv, bv.bv_offset))

			goto split;



		if (prev && blk_queue_cluster(q)) {
@@ -484,12 +483,12 @@ static bool req_no_special_merge(struct request *req) 
	return !q->mq_ops && req->special;

}



static int req_gap_to_prev(struct request *req, struct request *next)

static int req_gap_to_prev(struct request *req, struct bio *next)

{

	struct bio *prev = req->biotail;



	return bvec_gap_to_prev(&prev->bi_io_vec[prev->bi_vcnt - 1],

				next->bio->bi_io_vec[0].bv_offset);

	return bvec_gap_to_prev(req->q, &prev->bi_io_vec[prev->bi_vcnt - 1],

			next->bi_io_vec[1].bv_offset);

}



static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
@@ -506,8 +505,7 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 
	if (req_no_special_merge(req) || req_no_special_merge(next))

		return 0;



	if (test_bit(QUEUE_FLAG_SG_GAPS, &q->queue_flags) &&

	    req_gap_to_prev(req, next))

	if (req_gap_to_prev(req, next->bio))

		return 0;



	/*
@@ -692,8 +690,6 @@ int blk_attempt_req_merge(struct request_queue *q, struct request *rq, 


bool blk_rq_merge_ok(struct request *rq, struct bio *bio)

{

	struct request_queue *q = rq->q;



	if (!rq_mergeable(rq) || !bio_mergeable(bio))

		return false;
@@ -718,13 +714,8 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 
		return false;



	/* Only check gaps if the bio carries data */

	if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS) && bio_has_data(bio)) {

		struct bio_vec *bprev;



		bprev = &rq->biotail->bi_io_vec[rq->biotail->bi_vcnt - 1];

		if (bvec_gap_to_prev(bprev, bio->bi_io_vec[0].bv_offset))

	if (bio_has_data(bio) && req_gap_to_prev(rq, bio))

		return false;

	}



	return true;

}

block/blk-settings.c

+14 −0
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ void blk_set_default_limits(struct queue_limits *lim) 
	lim->max_segments = BLK_MAX_SEGMENTS;

	lim->max_integrity_segments = 0;

	lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;

	lim->virt_boundary_mask = 0;

	lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;

	lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;

	lim->chunk_sectors = 0;
@@ -532,6 +533,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, 


	t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,

					    b->seg_boundary_mask);

	t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask,

					    b->virt_boundary_mask);



	t->max_segments = min_not_zero(t->max_segments, b->max_segments);

	t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
@@ -771,6 +774,17 @@ void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) 
}

EXPORT_SYMBOL(blk_queue_segment_boundary);



/**

 * blk_queue_virt_boundary - set boundary rules for bio merging

 * @q:  the request queue for the device

 * @mask:  the memory boundary mask

 **/

void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)

{

	q->limits.virt_boundary_mask = mask;

}

EXPORT_SYMBOL(blk_queue_virt_boundary);



/**

 * blk_queue_dma_alignment - set dma length and memory alignment

 * @q:     the request queue for the device

drivers/block/nvme-core.c

+1 −1
Original line number Diff line number Diff line
@@ -2067,7 +2067,6 @@ static void nvme_alloc_ns(struct nvme_dev *dev, unsigned nsid) 
		goto out_free_ns;

	queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, ns->queue);

	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, ns->queue);

	queue_flag_set_unlocked(QUEUE_FLAG_SG_GAPS, ns->queue);

	ns->dev = dev;

	ns->queue->queuedata = ns;
@@ -2087,6 +2086,7 @@ static void nvme_alloc_ns(struct nvme_dev *dev, unsigned nsid) 
		blk_queue_chunk_sectors(ns->queue, dev->stripe_size >> 9);

	if (dev->vwc & NVME_CTRL_VWC_PRESENT)

		blk_queue_flush(ns->queue, REQ_FLUSH | REQ_FUA);

	blk_queue_virt_boundary(ns->queue, dev->page_size - 1);



	disk->major = nvme_major;

	disk->first_minor = 0;

drivers/md/dm-table.c

+0 −13
Original line number Diff line number Diff line
@@ -1380,14 +1380,6 @@ static int queue_supports_sg_merge(struct dm_target *ti, struct dm_dev *dev, 
	return q && !test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags);

}



static int queue_supports_sg_gaps(struct dm_target *ti, struct dm_dev *dev,

				  sector_t start, sector_t len, void *data)

{

	struct request_queue *q = bdev_get_queue(dev->bdev);



	return q && !test_bit(QUEUE_FLAG_SG_GAPS, &q->queue_flags);

}



static bool dm_table_all_devices_attribute(struct dm_table *t,

					   iterate_devices_callout_fn func)

{
@@ -1508,11 +1500,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, 
	else

		queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);



	if (dm_table_all_devices_attribute(t, queue_supports_sg_gaps))

		queue_flag_clear_unlocked(QUEUE_FLAG_SG_GAPS, q);

	else

		queue_flag_set_unlocked(QUEUE_FLAG_SG_GAPS, q);



	dm_table_set_integrity(t);



	/*

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