We only need to split bios if we want to read around the cache,
as when we go through the cache, the sharing is already done.
So use bio_multi_split to split up read requests, and get rid of
raid5_mergeable_bvec as it is no longer needed.
Signed-off-by: Neil Brown <[email protected]>
### Diffstat output
./drivers/md/raid5.c | 86 ++++++++++-----------------------------------------
1 file changed, 18 insertions(+), 68 deletions(-)
diff .prev/drivers/md/raid5.c ./drivers/md/raid5.c
--- .prev/drivers/md/raid5.c 2007-07-31 11:21:22.000000000 +1000
+++ ./drivers/md/raid5.c 2007-07-31 11:21:25.000000000 +1000
@@ -3805,39 +3805,6 @@ static int raid5_congested(void *data, i
return 0;
}
-/* We want read requests to align with chunks where possible,
- * but write requests don't need to.
- */
-static int raid5_mergeable_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *biovec)
-{
- mddev_t *mddev = q->queuedata;
- sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
- int max;
- unsigned int chunk_sectors = mddev->chunk_size >> 9;
- unsigned int bio_sectors = bio->bi_size >> 9;
-
- if (bio_data_dir(bio) == WRITE)
- return biovec->bv_len; /* always allow writes to be mergeable */
-
- max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
- if (max < 0) max = 0;
- if (max <= biovec->bv_len && bio_sectors == 0)
- return biovec->bv_len;
- else
- return max;
-}
-
-
-static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
-{
- sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
- unsigned int chunk_sectors = mddev->chunk_size >> 9;
- unsigned int bio_sectors = bio->bi_size >> 9;
-
- return chunk_sectors >=
- ((sector & (chunk_sectors - 1)) + bio_sectors);
-}
-
/*
* add bio to the retry LIFO ( in O(1) ... we are in interrupt )
* later sampled by raid5d.
@@ -3914,23 +3881,6 @@ static void raid5_align_endio(struct bio
add_bio_to_retry(raid_bi, conf);
}
-static int bio_fits_rdev(struct bio *bi)
-{
- struct request_queue *q = bdev_get_queue(bi->bi_bdev);
-
- if ((bi->bi_size>>9) > q->max_sectors)
- return 0;
-
- if (q->merge_bvec_fn)
- /* it's too hard to apply the merge_bvec_fn at this stage,
- * just just give up
- */
- return 0;
-
- return 1;
-}
-
-
static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
{
mddev_t *mddev = q->queuedata;
@@ -3941,16 +3891,10 @@ static int chunk_aligned_read(struct req
struct bio* align_bi;
mdk_rdev_t *rdev;
- if (!in_chunk_boundary(mddev, raid_bio)) {
- pr_debug("chunk_aligned_read : non aligned\n");
- return 0;
- }
/*
* use bio_clone to make a copy of the bio
*/
align_bi = bio_clone(raid_bio, GFP_NOIO);
- if (!align_bi)
- return 0;
/*
* set bi_end_io to a new function, and set bi_private to the
* original bio.
@@ -3976,13 +3920,6 @@ static int chunk_aligned_read(struct req
align_bi->bi_bdev = rdev->bdev;
align_bi->bi_sector += rdev->data_offset;
- if (!bio_fits_rdev(align_bi)) {
- /* too big in some way */
- bio_put(align_bi);
- rdev_dec_pending(rdev, mddev);
- return 0;
- }
-
spin_lock_irq(&conf->device_lock);
wait_event_lock_irq(conf->wait_for_queue,
conf->quiesce == 0,
@@ -4021,9 +3958,24 @@ static int make_request(struct request_q
disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
if (rw == READ &&
- mddev->reshape_position == MaxSector &&
- chunk_aligned_read(q,bi))
- return 0;
+ mddev->reshape_position == MaxSector) {
+ struct bio *remainder = bi;
+ int chunk_sects = mddev->chunk_size >> 9;
+ while (chunk_sects < ((remainder->bi_sector & (chunk_sects - 1))
+ + (remainder->bi_size >> 9))) {
+ struct bio *new =
+ bio_multi_split(bi,
+ chunk_sects -
+ (remainder->bi_sector
+ & (chunk_sects - 1)),
+ &remainder);
+ if (!chunk_aligned_read(q, new))
+ make_request(q, new);
+ }
+ bi = remainder;
+ if (chunk_aligned_read(q, bi))
+ return 0;
+ }
logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
last_sector = bi->bi_sector + (bi->bi_size>>9);
@@ -4948,8 +4900,6 @@ static int run(mddev_t *mddev)
mddev->array_size = mddev->size * (conf->previous_raid_disks -
conf->max_degraded);
- blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
-
return 0;
abort:
if (conf) {
-
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