[PATCH 3/9] block: Move bouncing to generic_make_request()

Kent Overstreet
2013-11-04T23:40:20Z

Next patch is going to make generic_make_request() handle arbitrary
sized bios by splitting them if necessary. It makes more sense to call
blk_queue_bounce() first, partly so it's working on larger bios - but also the
code that splits bios, and __blk_recalc_rq_segments(), won't have to take into
account bouncing (as it'll already have been done).

Also, __blk_recalc_rq_segments() now doesn't have to take into account
potential bouncing - it's already been done.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
---
block/blk-core.c | 14 +++++++-------
block/blk-merge.c | 13 ++++---------
drivers/block/mtip32xx/mtip32xx.c | 2 --
drivers/block/pktcdvd.c | 2 --
4 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index d9cab97..3c7467e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1466,13 +1466,6 @@ void blk_queue_bio(struct request_queue *q, struct bio *bio)
struct request *req;
unsigned int request_count = 0;

- /*
- * low level driver can indicate that it wants pages above a
- * certain limit bounced to low memory (ie for highmem, or even
- * ISA dma in theory)
- */
- blk_queue_bounce(q, &bio);
-
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
bio_endio(bio, -EIO);
return;
@@ -1822,6 +1815,13 @@ void generic_make_request(struct bio *bio)
do {
struct request_queue *q = bdev_get_queue(bio->bi_bdev);

+ /*
+ * low level driver can indicate that it wants pages above a
+ * certain limit bounced to low memory (ie for highmem, or even
+ * ISA dma in theory)
+ */
+ blk_queue_bounce(q, &bio);
+
q->make_request_fn(q, bio);

bio = bio_list_pop(current->bio_list);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 953b8df..9680ec73 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -13,7 +13,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
struct bio *bio)
{
struct bio_vec bv, bvprv = { NULL };
- int cluster, high, highprv = 1;
+ int cluster, prev = 0;
unsigned int seg_size, nr_phys_segs;
struct bio *fbio, *bbio;
struct bvec_iter iter;
@@ -27,13 +27,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
nr_phys_segs = 0;
for_each_bio(bio) {
bio_for_each_segment(bv, bio, iter) {
- /*
- * the trick here is making sure that a high page is
- * never considered part of another segment, since that
- * might change with the bounce page.
- */
- high = page_to_pfn(bv.bv_page) > queue_bounce_pfn(q);
- if (!high && !highprv && cluster) {
+ if (prev && cluster) {
if (seg_size + bv.bv_len
> queue_max_segment_size(q))
goto new_segment;
@@ -44,6 +38,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,

seg_size += bv.bv_len;
bvprv = bv;
+ prev = 1;
continue;
}
new_segment:
@@ -53,8 +48,8 @@ new_segment:

nr_phys_segs++;
bvprv = bv;
+ prev = 1;
seg_size = bv.bv_len;
- highprv = high;
}
bbio = bio;
}
diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index 52b2f2a..d4c669b 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -4016,8 +4016,6 @@ static void mtip_make_request(struct request_queue *queue, struct bio *bio)

sg = mtip_hw_get_scatterlist(dd, &tag, unaligned);
if (likely(sg != NULL)) {
- blk_queue_bounce(queue, &bio);
-
if (unlikely((bio)->bi_vcnt > MTIP_MAX_SG)) {
dev_warn(&dd->pdev->dev,
"Maximum number of SGL entries exceeded\n");
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 1bf1f22..7991cc8 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2486,8 +2486,6 @@ static void pkt_make_request(struct request_queue *q, struct bio *bio)
goto end_io;
}

- blk_queue_bounce(q, &bio);
-
do {
sector_t zone = get_zone(bio->bi_iter.bi_sector, pd);
sector_t last_zone = get_zone(bio_end_sector(bio) - 1, pd);
--
1.8.4.rc3