[Xen-devel] [PATCH 08/11] xen-blkfront: remove bio splitting.

[NeilBrown <neilb@xxxxxxxx>]

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.

Signed-off-by: NeilBrown <neilb@xxxxxxxx>
---
 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 abed296ce605..b8930d9b7102 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;
-};
-
 static DEFINE_MUTEX(blkfront_mutex);
 static const struct block_device_operations xlvbd_block_fops;
 
@@ -1982,28 +1977,13 @@ 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(). */
@@ -2042,34 +2022,6 @@ 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);
        }
 



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