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md: raid0 :Enables chunk size other than powers of 2. 

Maintain two flows, one for pow2 chunk sizes (which uses masks and
shift), and a flow for the general case (which uses sector_div).
This is for the sake of performance.

 - introduce map_sector and is_io_in_chunk_boundary to encapsulate
   those two flows better for raid0_make_request
 - fix blk_mergeable to support the two flows.

Signed-off-by: raziebe@gmail.com
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
raz ben yehuda 2009-06-16 17:02:05 +10:00 committed by NeilBrown
parent 2ac06c3332
commit fbb704efb7
1 changed files with 77 additions and 30 deletions
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107
drivers/md/raid0.c
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@ -273,7 +273,12 @@ static int raid0_mergeable_bvec(struct request_queue *q,
unsigned int chunk_sectors = mddev->chunk_size >> 9;
unsigned int bio_sectors = bvm->bi_size >> 9;
max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
if (is_power_of_2(mddev->chunk_size))
max = (chunk_sectors - ((sector & (chunk_sectors-1))
+ bio_sectors)) << 9;
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 <= biovec->bv_len && bio_sectors == 0)
return biovec->bv_len;
@ -299,9 +304,8 @@ static int raid0_run(mddev_t *mddev)
{
int ret;
if (mddev->chunk_size == 0 ||
!is_power_of_2(mddev->chunk_size)) {
printk(KERN_ERR "md/raid0: chunk size must be a power of 2.\n");
if (mddev->chunk_size == 0) {
printk(KERN_ERR "md/raid0: chunk size must be set.\n");
return -EINVAL;
}
blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
@ -367,15 +371,65 @@ static struct strip_zone *find_zone(struct raid0_private_data *conf,
BUG();
}
static int raid0_make_request (struct request_queue *q, struct bio *bio)
/*
* remaps the bio to the target device. we separate two flows.
* power 2 flow and a general flow for the sake of perfromance
*/
static mdk_rdev_t *map_sector(mddev_t *mddev, struct strip_zone *zone,
sector_t sector, sector_t *sector_offset)
{
unsigned int sect_in_chunk;
sector_t chunk;
raid0_conf_t *conf = mddev->private;
unsigned int chunk_sects = mddev->chunk_size >> 9;
if (is_power_of_2(mddev->chunk_size)) {
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)*mddev->raid_disks
+ sector_div(sector, zone->nb_dev)];
}
/*
* Is io distribute over 1 or more chunks ?
*/
static inline int is_io_in_chunk_boundary(mddev_t *mddev,
unsigned int chunk_sects, struct bio *bio)
{
if (likely(is_power_of_2(mddev->chunk_size))) {
return chunk_sects >= ((bio->bi_sector & (chunk_sects-1))
+ (bio->bi_size >> 9));
} else{
sector_t sector = bio->bi_sector;
return chunk_sects >= (sector_div(sector, chunk_sects)
+ (bio->bi_size >> 9));
}
}
static int raid0_make_request(struct request_queue *q, struct bio *bio)
{
mddev_t *mddev = q->queuedata;
unsigned int sect_in_chunk, chunksect_bits, chunk_sects;
raid0_conf_t *conf = mddev->private;
unsigned int chunk_sects;
sector_t sector_offset;
struct strip_zone *zone;
mdk_rdev_t *tmp_dev;
sector_t chunk;
sector_t sector, rsect, sector_offset;
const int rw = bio_data_dir(bio);
int cpu;
@ -391,10 +445,8 @@ static int raid0_make_request (struct request_queue *q, struct bio *bio)
part_stat_unlock();
chunk_sects = mddev->chunk_size >> 9;
chunksect_bits = ffz(~chunk_sects);
sector = bio->bi_sector;
if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
if (unlikely(!is_io_in_chunk_boundary(mddev, chunk_sects, bio))) {
sector_t sector = bio->bi_sector;
struct bio_pair *bp;
/* Sanity check -- queue functions should prevent this happening */
if (bio->bi_vcnt != 1 ||
@ -403,7 +455,12 @@ static int raid0_make_request (struct request_queue *q, struct bio *bio)
/* This is a one page bio that upper layers
* refuse to split for us, so we need to split it.
*/
bp = bio_split(bio, chunk_sects - (bio->bi_sector & (chunk_sects - 1)));
if (likely(is_power_of_2(mddev->chunk_size)))
bp = bio_split(bio, chunk_sects - (sector &
(chunk_sects-1)));
else
bp = bio_split(bio, chunk_sects -
sector_div(sector, chunk_sects));
if (raid0_make_request(q, &bp->bio1))
generic_make_request(&bp->bio1);
if (raid0_make_request(q, &bp->bio2))
@ -412,24 +469,14 @@ static int raid0_make_request (struct request_queue *q, struct bio *bio)
bio_pair_release(bp);
return 0;
}
sector_offset = sector;
zone = find_zone(conf, &sector_offset);
sect_in_chunk = bio->bi_sector & (chunk_sects - 1);
{
sector_t x = sector_offset >> chunksect_bits;
sector_div(x, zone->nb_dev);
chunk = x;
x = sector >> chunksect_bits;
tmp_dev = conf->devlist[(zone - conf->strip_zone)*mddev->raid_disks
+ sector_div(x, zone->nb_dev)];
}
rsect = (chunk << chunksect_bits) + zone->dev_start + sect_in_chunk;
sector_offset = bio->bi_sector;
zone = find_zone(mddev->private, &sector_offset);
tmp_dev = map_sector(mddev, zone, bio->bi_sector,
&sector_offset);
bio->bi_bdev = tmp_dev->bdev;
bio->bi_sector = rsect + tmp_dev->data_offset;
bio->bi_sector = sector_offset + zone->dev_start +
tmp_dev->data_offset;
/*
* Let the main block layer submit the IO and resolve recursion:
*/