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block: Replace SG_GAPS with new queue limits mask

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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: Keith Busch <keith.busch@intel.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Keith Busch 2015-08-19 14:24:05 -07:00 committed by Jens Axboe
parent d2be537c3b
commit 03100aada9
7 changed files with 43 additions and 42 deletions
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3
block/bio.c
View File

@ -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;
}

23
block/blk-merge.c
View File

@ -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))
return false;
}
if (bio_has_data(bio) && req_gap_to_prev(rq, bio))
return false;
return true;
}

14
block/blk-settings.c
View File

@ -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

2
drivers/block/nvme-core.c
View File

@ -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;

13
drivers/md/dm-table.c
View File

@ -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);
/*

9
include/linux/bio.h
View File

@ -186,15 +186,6 @@ static inline void *bio_data(struct bio *bio)
#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
/*
* Check if adding a bio_vec after bprv with offset would create a gap in
* the SG list. Most drivers don't care about this, but some do.
*/
static inline bool bvec_gap_to_prev(struct bio_vec *bprv, unsigned int offset)
{
return offset || ((bprv->bv_offset + bprv->bv_len) & (PAGE_SIZE - 1));
}
/*
* drivers should _never_ use the all version - the bio may have been split
* before it got to the driver and the driver won't own all of it

21
include/linux/blkdev.h
View File

@ -250,6 +250,7 @@ struct blk_queue_tag {
struct queue_limits {
unsigned long bounce_pfn;
unsigned long seg_boundary_mask;
unsigned long virt_boundary_mask;
unsigned int max_hw_sectors;
unsigned int chunk_sectors;
@ -479,7 +480,6 @@ struct request_queue {
#define QUEUE_FLAG_DEAD 19 /* queue tear-down finished */
#define QUEUE_FLAG_INIT_DONE 20 /* queue is initialized */
#define QUEUE_FLAG_NO_SG_MERGE 21 /* don't attempt to merge SG segments*/
#define QUEUE_FLAG_SG_GAPS 22 /* queue doesn't support SG gaps */
#define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_STACKABLE) | \
@ -981,6 +981,7 @@ extern int blk_queue_dma_drain(struct request_queue *q,
void *buf, unsigned int size);
extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn);
extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
extern void blk_queue_virt_boundary(struct request_queue *, unsigned long);
extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
extern void blk_queue_unprep_rq(struct request_queue *, unprep_rq_fn *ufn);
extern void blk_queue_dma_alignment(struct request_queue *, int);
@ -1149,6 +1150,11 @@ static inline unsigned long queue_segment_boundary(struct request_queue *q)
return q->limits.seg_boundary_mask;
}
static inline unsigned long queue_virt_boundary(struct request_queue *q)
{
return q->limits.virt_boundary_mask;
}
static inline unsigned int queue_max_sectors(struct request_queue *q)
{
return q->limits.max_sectors;
@ -1349,6 +1355,19 @@ static inline void put_dev_sector(Sector p)
page_cache_release(p.v);
}
/*
* Check if adding a bio_vec after bprv with offset would create a gap in
* the SG list. Most drivers don't care about this, but some do.
*/
static inline bool bvec_gap_to_prev(struct request_queue *q,
struct bio_vec *bprv, unsigned int offset)
{
if (!queue_virt_boundary(q))
return false;
return offset ||
((bprv->bv_offset + bprv->bv_len) & queue_virt_boundary(q));
}
struct work_struct;
int kblockd_schedule_work(struct work_struct *work);
int kblockd_schedule_delayed_work(struct delayed_work *dwork, unsigned long delay);