[PATCH 6/9] mtip32xx: handle arbitrary size bios

Kent Overstreet
2013-11-04T23:38:52Z

We get a measurable performance increase by handling this in the driver when
we're already looping over the biovec, instead of handling it separately in
generic_make_request() (or bio_add_page() originally)

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
---
drivers/block/mtip32xx/mtip32xx.c | 46 +++++++++++++--------------------------
1 file changed, 15 insertions(+), 31 deletions(-)

diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index d4c669b..c5a7a96 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -2648,24 +2648,6 @@ static void mtip_hw_submit_io(struct driver_data *dd, sector_t sector,
}

/*
- * Release a command slot.
- *
- * @dd Pointer to the driver data structure.
- * @tag Slot tag
- *
- * return value
- * None
- */
-static void mtip_hw_release_scatterlist(struct driver_data *dd, int tag,
- int unaligned)
-{
- struct semaphore *sem = unaligned ? &dd->port->cmd_slot_unal :
- &dd->port->cmd_slot;
- release_slot(dd->port, tag);
- up(sem);
-}
-
-/*
* Obtain a command slot and return its associated scatter list.
*
* @dd Pointer to the driver data structure.
@@ -4016,21 +3998,22 @@ static void mtip_make_request(struct request_queue *queue, struct bio *bio)

sg = mtip_hw_get_scatterlist(dd, &tag, unaligned);
if (likely(sg != NULL)) {
- if (unlikely((bio)->bi_vcnt > MTIP_MAX_SG)) {
- dev_warn(&dd->pdev->dev,
- "Maximum number of SGL entries exceeded\n");
- bio_io_error(bio);
- mtip_hw_release_scatterlist(dd, tag, unaligned);
- return;
- }
-
/* Create the scatter list for this bio. */
bio_for_each_segment(bvec, bio, iter) {
- sg_set_page(&sg[nents],
- bvec.bv_page,
- bvec.bv_len,
- bvec.bv_offset);
- nents++;
+ if (unlikely(nents == MTIP_MAX_SG)) {
+ struct bio *split = bio_clone(bio, GFP_NOIO);
+
+ split->bi_iter = iter;
+ bio->bi_iter.bi_size -= iter.bi_size;
+ bio_chain(split, bio);
+ generic_make_request(split);
+ break;
+ }
+
+ sg_set_page(&sg[nents++],
+ bvec.bv_page,
+ bvec.bv_len,
+ bvec.bv_offset);
}

/* Issue the read/write. */
@@ -4145,6 +4128,7 @@ skip_create_disk:
blk_queue_max_hw_sectors(dd->queue, 0xffff);
blk_queue_max_segment_size(dd->queue, 0x400000);
blk_queue_io_min(dd->queue, 4096);
+ set_bit(QUEUE_FLAG_LARGEBIOS, &dd->queue->queue_flags);

/*
* write back cache is not supported in the device. FUA depends on
--
1.8.4.rc3