From ba13da47ffa202784355561f72160a41350e95cc Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 19 Mar 2012 12:46:39 +1100 Subject: md: add proper merge_bvec handling to RAID0 and Linear. 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 --- drivers/md/linear.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) (limited to 'drivers/md/linear.c') diff --git a/drivers/md/linear.c b/drivers/md/linear.c index 67940741b19..b0fcc7d02ad 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++; -- cgit v1.2.3