[PATCHv4] blk: Replace SG_GAPGS with new queue limits mask
Keith Busch
keith.busch at intel.com
Tue Aug 4 12:32:13 PDT 2015
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 at intel.com>
---
v3->v4:
Simplified invoking bvec_gap_to_prev() by adding the request_queue
parameter. A side effect from this required the function be moved form
bio.h to blkdev.h to resolve a circular header dependency.
block/bio.c | 3 +--
block/blk-merge.c | 20 ++++++--------------
block/blk-settings.c | 14 ++++++++++++++
drivers/block/nvme-core.c | 2 +-
drivers/md/dm-table.c | 13 -------------
include/linux/bio.h | 9 ---------
include/linux/blkdev.h | 21 ++++++++++++++++++++-
7 files changed, 42 insertions(+), 40 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index d6e5ba3..679a0fc 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -770,8 +770,7 @@ static int __bio_add_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;
}
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 30a0d9f..2030ccb 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -356,12 +356,12 @@ 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,
@@ -378,8 +378,7 @@ 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;
/*
@@ -564,8 +563,6 @@ 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;
@@ -590,13 +587,8 @@ 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;
}
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 12600bf..1e9fc6c 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -111,6 +111,7 @@ 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;
@@ -550,6 +551,8 @@ 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,
@@ -788,6 +791,17 @@ 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
* @mask: alignment mask
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 7920c27..7e9dd11 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -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;
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 16ba55a..b3a8ab0 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1388,14 +1388,6 @@ 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)
{
@@ -1516,11 +1508,6 @@ 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);
/*
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 5e963a6..8acb76c 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -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));
-}
-
#define bio_io_error(bio) bio_endio((bio), -EIO)
/*
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d4068c1..68adec9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -258,6 +258,7 @@ 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;
@@ -486,7 +487,6 @@ 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) | \
@@ -986,6 +986,7 @@ 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_merge_bvec(struct request_queue *, merge_bvec_fn *);
@@ -1154,6 +1155,11 @@ 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;
@@ -1354,6 +1360,19 @@ 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);
--
1.7.10.4
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