[PATCH 10/13] xen-blkfront: remove bio splitting.

NeilBrown
2017-05-02T03:42:25Z

bios that are re-submitted will pass through blk_queue_split() when
blk_queue_bio() is called, and this will split the bio if necessary.
There is no longer any need to do this splitting in xen-blkfront.

Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: NeilBrown <neilb@suse.com>
---
drivers/block/xen-blkfront.c | 54 ++----------------------------------------
1 file changed, 3 insertions(+), 51 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 39459631667c..fb963a010d4d 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -110,11 +110,6 @@ struct blk_shadow {
unsigned long associated_id;
};

-struct split_bio {
- struct bio *bio;
- atomic_t pending;
-};
-
struct blkif_req {
int error;
};
@@ -1996,28 +1991,13 @@ static int blkfront_probe(struct xenbus_device *dev,
return 0;
}

-static void split_bio_end(struct bio *bio)
-{
- struct split_bio *split_bio = bio->bi_private;
-
- if (atomic_dec_and_test(&split_bio->pending)) {
- split_bio->bio->bi_phys_segments = 0;
- split_bio->bio->bi_error = bio->bi_error;
- bio_endio(split_bio->bio);
- kfree(split_bio);
- }
- bio_put(bio);
-}
-
static int blkif_recover(struct blkfront_info *info)
{
- unsigned int i, r_index;
+ unsigned int r_index;
struct request *req, *n;
int rc;
- struct bio *bio, *cloned_bio;
- unsigned int segs, offset;
- int pending, size;
- struct split_bio *split_bio;
+ struct bio *bio;
+ unsigned int segs;

blkfront_gather_backend_features(info);
/* Reset limits changed by blk_mq_update_nr_hw_queues(). */
@@ -2056,34 +2036,6 @@ static int blkif_recover(struct blkfront_info *info)

while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
/* Traverse the list of pending bios and re-queue them */
- if (bio_segments(bio) > segs) {
- /*
- * This bio has more segments than what we can
- * handle, we have to split it.
- */
- pending = (bio_segments(bio) + segs - 1) / segs;
- split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
- BUG_ON(split_bio == NULL);
- atomic_set(&split_bio->pending, pending);
- split_bio->bio = bio;
- for (i = 0; i < pending; i++) {
- offset = (i * segs * XEN_PAGE_SIZE) >> 9;
- size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9,
- (unsigned int)bio_sectors(bio) - offset);
- cloned_bio = bio_clone(bio, GFP_NOIO);
- BUG_ON(cloned_bio == NULL);
- bio_trim(cloned_bio, offset, size);
- cloned_bio->bi_private = split_bio;
- cloned_bio->bi_end_io = split_bio_end;
- submit_bio(cloned_bio);
- }
- /*
- * Now we have to wait for all those smaller bios to
- * end, so we can also end the "parent" bio.
- */
- continue;
- }
- /* We don't need to split this bio */
submit_bio(bio);
}