These personalities currently set a max request size of one page
when any member device has a merge_bvec_fn because they don't
bother to call that function.
This causes extra works in splitting and combining requests.
So make the extra effort to call the merge_bvec_fn when it exists
so that we end up with larger requests out the bottom.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
drivers/md/linear.c | 30 +++++-----
drivers/md/raid0.c | 154 ++++++++++++++++++++++++++++-----------------------
drivers/md/raid0.h | 11 ++--
3 files changed, 107 insertions(+), 88 deletions(-)
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 6794074..b0fcc7d 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -68,10 +68,19 @@ static int linear_mergeable_bvec(struct request_queue *q,
struct dev_info *dev0;
unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
+ int maxbytes = biovec->bv_len;
+ struct request_queue *subq;
rcu_read_lock();
dev0 = which_dev(mddev, sector);
maxsectors = dev0->end_sector - sector;
+ subq = bdev_get_queue(dev0->rdev->bdev);
+ if (subq->merge_bvec_fn) {
+ bvm->bi_bdev = dev0->rdev->bdev;
+ bvm->bi_sector -= dev0->end_sector - dev0->rdev->sectors;
+ maxbytes = min(maxbytes, subq->merge_bvec_fn(subq, bvm,
+ biovec));
+ }
rcu_read_unlock();
if (maxsectors < bio_sectors)
@@ -80,12 +89,12 @@ static int linear_mergeable_bvec(struct request_queue *q,
maxsectors -= bio_sectors;
if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
- return biovec->bv_len;
- /* The bytes available at this offset could be really big,
- * so we cap at 2^31 to avoid overflow */
- if (maxsectors > (1 << (31-9)))
- return 1<<31;
- return maxsectors << 9;
+ return maxbytes;
+
+ if (maxsectors > (maxbytes >> 9))
+ return maxbytes;
+ else
+ return maxsectors << 9;
}
static int linear_congested(void *data, int bits)
@@ -158,15 +167,6 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
disk_stack_limits(mddev->gendisk, rdev->bdev,
rdev->data_offset << 9);
- /* as we don't honour merge_bvec_fn, we must never risk
- * violating it, so limit max_segments to 1 lying within
- * a single page.
- */
- if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
- blk_queue_max_segments(mddev->queue, 1);
- blk_queue_segment_boundary(mddev->queue,
- PAGE_CACHE_SIZE - 1);
- }
conf->array_sectors += rdev->sectors;
cnt++;
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 7ef5cbf..6f31f55 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -188,16 +188,10 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
disk_stack_limits(mddev->gendisk, rdev1->bdev,
rdev1->data_offset << 9);
- /* as we don't honour merge_bvec_fn, we must never risk
- * violating it, so limit ->max_segments to 1, lying within
- * a single page.
- */
- if (rdev1->bdev->bd_disk->queue->merge_bvec_fn) {
- blk_queue_max_segments(mddev->queue, 1);
- blk_queue_segment_boundary(mddev->queue,
- PAGE_CACHE_SIZE - 1);
- }
+ if (rdev1->bdev->bd_disk->queue->merge_bvec_fn)
+ conf->has_merge_bvec = 1;
+
if (!smallest || (rdev1->sectors < smallest->sectors))
smallest = rdev1;
cnt++;
@@ -290,8 +284,64 @@ abort:
return err;
}
+/* Find the zone which holds a particular offset
+ * Update *sectorp to be an offset in that zone
+ */
+static struct strip_zone *find_zone(struct r0conf *conf,
+ sector_t *sectorp)
+{
+ int i;
+ struct strip_zone *z = conf->strip_zone;
+ sector_t sector = *sectorp;
+
+ for (i = 0; i < conf->nr_strip_zones; i++)
+ if (sector < z[i].zone_end) {
+ if (i)
+ *sectorp = sector - z[i-1].zone_end;
+ return z + i;
+ }
+ BUG();
+}
+
+/*
+ * remaps the bio to the target device. we separate two flows.
+ * power 2 flow and a general flow for the sake of perfromance
+*/
+static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
+ sector_t sector, sector_t *sector_offset)
+{
+ unsigned int sect_in_chunk;
+ sector_t chunk;
+ struct r0conf *conf = mddev->private;
+ int raid_disks = conf->strip_zone[0].nb_dev;
+ unsigned int chunk_sects = mddev->chunk_sectors;
+
+ if (is_power_of_2(chunk_sects)) {
+ int chunksect_bits = ffz(~chunk_sects);
+ /* find the sector offset inside the chunk */
+ sect_in_chunk = sector & (chunk_sects - 1);
+ sector >>= chunksect_bits;
+ /* chunk in zone */
+ chunk = *sector_offset;
+ /* quotient is the chunk in real device*/
+ sector_div(chunk, zone->nb_dev << chunksect_bits);
+ } else{
+ sect_in_chunk = sector_div(sector, chunk_sects);
+ chunk = *sector_offset;
+ sector_div(chunk, chunk_sects * zone->nb_dev);
+ }
+ /*
+ * position the bio over the real device
+ * real sector = chunk in device + starting of zone
+ * + the position in the chunk
+ */
+ *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
+ return conf->devlist[(zone - conf->strip_zone)*raid_disks
+ + sector_div(sector, zone->nb_dev)];
+}
+
/**
- * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
+ * raid0_mergeable_bvec -- tell bio layer if two requests can be merged
* @q: request queue
* @bvm: properties of new bio
* @biovec: the request that could be merged to it.
@@ -303,10 +353,15 @@ static int raid0_mergeable_bvec(struct request_queue *q,
struct bio_vec *biovec)
{
struct mddev *mddev = q->queuedata;
+ struct r0conf *conf = mddev->private;
sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
+ sector_t sector_offset = sector;
int max;
unsigned int chunk_sectors = mddev->chunk_sectors;
unsigned int bio_sectors = bvm->bi_size >> 9;
+ struct strip_zone *zone;
+ struct md_rdev *rdev;
+ struct request_queue *subq;
if (is_power_of_2(chunk_sectors))
max = (chunk_sectors - ((sector & (chunk_sectors-1))
@@ -314,10 +369,27 @@ static int raid0_mergeable_bvec(struct request_queue *q,
else
max = (chunk_sectors - (sector_div(sector, chunk_sectors)
+ bio_sectors)) << 9;
- if (max < 0) max = 0; /* bio_add cannot handle a negative return */
+ if (max < 0)
+ max = 0; /* bio_add cannot handle a negative return */
if (max <= biovec->bv_len && bio_sectors == 0)
return biovec->bv_len;
- else
+ if (max < biovec->bv_len)
+ /* too small already, no need to check further */
+ return max;
+ if (!conf->has_merge_bvec)
+ return max;
+
+ /* May need to check subordinate device */
+ sector = sector_offset;
+ zone = find_zone(mddev->private, §or_offset);
+ rdev = map_sector(mddev, zone, sector, §or_offset);
+ subq = bdev_get_queue(rdev->bdev);
+ if (subq->merge_bvec_fn) {
+ bvm->bi_bdev = rdev->bdev;
+ bvm->bi_sector = sector_offset + zone->dev_start +
+ rdev->data_offset;
+ return min(max, subq->merge_bvec_fn(subq, bvm, biovec));
+ } else
return max;
}
@@ -397,62 +469,6 @@ static int raid0_stop(struct mddev *mddev)
return 0;
}
-/* Find the zone which holds a particular offset
- * Update *sectorp to be an offset in that zone
- */
-static struct strip_zone *find_zone(struct r0conf *conf,
- sector_t *sectorp)
-{
- int i;
- struct strip_zone *z = conf->strip_zone;
- sector_t sector = *sectorp;
-
- for (i = 0; i < conf->nr_strip_zones; i++)
- if (sector < z[i].zone_end) {
- if (i)
- *sectorp = sector - z[i-1].zone_end;
- return z + i;
- }
- BUG();
-}
-
-/*
- * remaps the bio to the target device. we separate two flows.
- * power 2 flow and a general flow for the sake of perfromance
-*/
-static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
- sector_t sector, sector_t *sector_offset)
-{
- unsigned int sect_in_chunk;
- sector_t chunk;
- struct r0conf *conf = mddev->private;
- int raid_disks = conf->strip_zone[0].nb_dev;
- unsigned int chunk_sects = mddev->chunk_sectors;
-
- if (is_power_of_2(chunk_sects)) {
- int chunksect_bits = ffz(~chunk_sects);
- /* find the sector offset inside the chunk */
- sect_in_chunk = sector & (chunk_sects - 1);
- sector >>= chunksect_bits;
- /* chunk in zone */
- chunk = *sector_offset;
- /* quotient is the chunk in real device*/
- sector_div(chunk, zone->nb_dev << chunksect_bits);
- } else{
- sect_in_chunk = sector_div(sector, chunk_sects);
- chunk = *sector_offset;
- sector_div(chunk, chunk_sects * zone->nb_dev);
- }
- /*
- * position the bio over the real device
- * real sector = chunk in device + starting of zone
- * + the position in the chunk
- */
- *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
- return conf->devlist[(zone - conf->strip_zone)*raid_disks
- + sector_div(sector, zone->nb_dev)];
-}
-
/*
* Is io distribute over 1 or more chunks ?
*/
@@ -505,7 +521,7 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio)
}
sector_offset = bio->bi_sector;
- zone = find_zone(mddev->private, §or_offset);
+ zone = find_zone(mddev->private, §or_offset);
tmp_dev = map_sector(mddev, zone, bio->bi_sector,
§or_offset);
bio->bi_bdev = tmp_dev->bdev;
diff --git a/drivers/md/raid0.h b/drivers/md/raid0.h
index 0884bba..05539d9 100644
--- a/drivers/md/raid0.h
+++ b/drivers/md/raid0.h
@@ -4,13 +4,16 @@
struct strip_zone {
sector_t zone_end; /* Start of the next zone (in sectors) */
sector_t dev_start; /* Zone offset in real dev (in sectors) */
- int nb_dev; /* # of devices attached to the zone */
+ int nb_dev; /* # of devices attached to the zone */
};
struct r0conf {
- struct strip_zone *strip_zone;
- struct md_rdev **devlist; /* lists of rdevs, pointed to by strip_zone->dev */
- int nr_strip_zones;
+ struct strip_zone *strip_zone;
+ struct md_rdev **devlist; /* lists of rdevs, pointed to
+ * by strip_zone->dev */
+ int nr_strip_zones;
+ int has_merge_bvec; /* at least one member has
+ * a merge_bvec_fn */
};
#endif
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