Enables chunk size other than 4K.
2. Maintain two flows, one for pow2 chunk sizes and a flow for the general case.
This is for the sake of performance.
3. in make_request move the splliting code after the likely code. It is
possible for the compiler to neglect ( gcc .. -Os.. see What
programmer should know about memory,urlich dreper, page 57)
4. add a memeory allocation check after the bio_split.
5. inroduce map_sector as the remapping of the bio in the common case.
6. fix blk_mergeable to support the two flows.
raid0.c | 163 +++++++++++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 116 insertions(+), 47 deletions(-)
Signed-off-by: raziebe@xxxxxxxxx
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 0a6d0fa..a994169 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -23,6 +23,7 @@
#include "md.h"
#include "raid0.h"
+
static void raid0_unplug(struct request_queue *q)
{
mddev_t *mddev = q->queuedata;
@@ -265,7 +266,12 @@ 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;
@@ -358,15 +364,73 @@ 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;
- raid0_conf_t *conf = mddev->private;
- struct strip_zone *zone;
- mdk_rdev_t *tmp_dev;
+ sector_t sect_in_chunk;
sector_t chunk;
- sector_t sector, rsect, sector_offset;
+ sector_t x;
+ raid0_conf_t *conf = mddev->private;
+ sector_t 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);
+ /* chunk in zone */
+ x = *sector_offset >> chunksect_bits;
+ /* quotient is the chunk in real device*/
+ sector_div(x, zone->nb_dev);
+ chunk = x;
+ /*
+ * we treat the device list a two dimensional array.
+ * devices row + offset inside the devices row = real dev
+ */
+ x = sector >> chunksect_bits;
+ } else{
+ x = sector;
+ sect_in_chunk = sector_div(x, chunk_sects);
+ x = *sector_offset;
+ sector_div(x, chunk_sects);
+ sector_div(x, zone->nb_dev);
+ chunk = x;
+ x = sector;
+ sector_div(x, chunk_sects);
+ }
+ /*
+ * 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(x, 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;
const int rw = bio_data_dir(bio);
int cpu;
@@ -382,55 +446,60 @@ 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))) {
- struct bio_pair *bp;
- /* Sanity check -- queue functions should prevent this happening */
- if (bio->bi_vcnt != 1 ||
- bio->bi_idx != 0)
- goto bad_map;
- /* 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 (raid0_make_request(q, &bp->bio1))
- generic_make_request(&bp->bio1);
- if (raid0_make_request(q, &bp->bio2))
- generic_make_request(&bp->bio2);
-
- bio_pair_release(bp);
- return 0;
+ if (likely(is_io_in_chunk_boundary(mddev, chunk_sects, bio))) {
+ mdk_rdev_t *tmp_dev;
+ sector_t sector_offset = bio->bi_sector;
+ struct strip_zone *zone = find_zone(mddev->private,
+ §or_offset);
+ tmp_dev = map_sector(mddev, zone, bio->bi_sector,
+ §or_offset);
+ bio->bi_bdev = tmp_dev->bdev;
+ bio->bi_sector = sector_offset + zone->dev_start +
+ tmp_dev->data_offset;
+ /* let upper layer do the actual io */
+ return 1;
}
- sector_offset = sector;
- zone = find_zone(conf, §or_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)];
+ /*
+ * the bio splits over two chunks at least
+ */
+ sector_t sector = bio->bi_sector;
+ struct bio_pair *bp;
+ mddev_t *mddev = q->queuedata;
+ /* Sanity check -- queue functions should prevent this happening */
+ if (bio->bi_vcnt != 1 || bio->bi_idx != 0)
+ goto bad_map;
+ /* This is a one page bio that upper layers
+ * refuse to split for us, so we need to split it.
+ */
+ if (likely(is_power_of_2(mddev->chunk_size)))
+ bp = bio_split(bio, chunk_sects - (bio->bi_sector &
+ (chunk_sects-1)));
+ else
+ bp = bio_split(bio, chunk_sects -
+ sector_div(sector, chunk_sects));
+ if (!bp) {
+ printk(KERN_ERR "%s: Critical error,failed to "
+ "split bio\n", mdname(mddev));
+ goto bad_map;
}
- rsect = (chunk << chunksect_bits) + zone->dev_start + sect_in_chunk;
-
- bio->bi_bdev = tmp_dev->bdev;
- bio->bi_sector = rsect + tmp_dev->data_offset;
+ if (raid0_make_request(q, &bp->bio1))
+ generic_make_request(&bp->bio1);
+ if (raid0_make_request(q, &bp->bio2))
+ generic_make_request(&bp->bio2);
+ bio_pair_release(bp);
/*
- * Let the main block layer submit the IO and resolve recursion:
+ * handle split already made the ios
+ * report all ok and leave
*/
- return 1;
+ return 0;
+ }
-bad_map:
printk("raid0_make_request bug: can't convert block across chunks"
" or bigger than %dk %llu %d\n", chunk_sects / 2,
(unsigned long long)bio->bi_sector, bio->bi_size >> 10);
-
+bad_map:
bio_io_error(bio);
return 0;
}
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