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authorraz ben yehuda <raziebe@gmail.com>2009-06-16 17:02:05 +1000
committerNeilBrown <neilb@suse.de>2009-06-16 17:02:05 +1000
commitfbb704efb784e2c8418e34dc3013af76bdd58101 (patch)
tree814820430d00128cb5f3fc0d44bb579c19d5d2a9 /drivers/md/raid0.c
parent2ac06c3332898103210b478c5a17c20e28929287 (diff)
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>
Diffstat (limited to 'drivers/md/raid0.c')
-rw-r--r--drivers/md/raid0.c107
1 files changed, 77 insertions, 30 deletions
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 39936a217f9..7cd2671cc79 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -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)
{
- mddev_t *mddev = q->queuedata;
- unsigned int sect_in_chunk, chunksect_bits, chunk_sects;
+ 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 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:
*/