dm thin: use __blkdev_issue_discard for async discard support

With commit 38f25255330 ("block: add __blkdev_issue_discard") DM thinp
no longer needs to carry its own async discard method.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 16 insertions, 54 deletions

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index da42c4916ce6..598a78ba894b 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -322,56 +322,6 @@ struct thin_c {
 
 /*----------------------------------------------------------------*/
 
-/**
- * __blkdev_issue_discard_async - queue a discard with async completion
- * @bdev:       blockdev to issue discard for
- * @sector:     start sector
- * @nr_sects:   number of sectors to discard
- * @gfp_mask:   memory allocation flags (for bio_alloc)
- * @flags:      BLKDEV_IFL_* flags to control behaviour
- * @parent_bio: parent discard bio that all sub discards get chained to
- *
- * Description:
- *    Asynchronously issue a discard request for the sectors in question.
- */
-static int __blkdev_issue_discard_async(struct block_device *bdev, sector_t sector,
-                                        sector_t nr_sects, gfp_t gfp_mask, unsigned long flags,
-                                        struct bio *parent_bio)
-{
-        struct request_queue *q = bdev_get_queue(bdev);
-        int type = REQ_WRITE | REQ_DISCARD;
-        struct bio *bio;
-
-        if (!q || !nr_sects)
-                return -ENXIO;
-
-        if (!blk_queue_discard(q))
-                return -EOPNOTSUPP;
-
-        if (flags & BLKDEV_DISCARD_SECURE) {
-                if (!blk_queue_secdiscard(q))
-                        return -EOPNOTSUPP;
-                type |= REQ_SECURE;
-        }
-
-        /*
-         * Required bio_put occurs in bio_endio thanks to bio_chain below
-         */
-        bio = bio_alloc(gfp_mask, 1);
-        if (!bio)
-                return -ENOMEM;
-
-        bio_chain(bio, parent_bio);
-
-        bio->bi_iter.bi_sector = sector;
-        bio->bi_bdev = bdev;
-        bio->bi_iter.bi_size = nr_sects << 9;
-
-        submit_bio(type, bio);
-
-        return 0;
-}
-
 static bool block_size_is_power_of_two(struct pool *pool)
 {
         return pool->sectors_per_block_shift >= 0;
@@ -387,11 +337,23 @@ static sector_t block_to_sectors(struct pool *pool, dm_block_t b)
 static int issue_discard(struct thin_c *tc, dm_block_t data_b, dm_block_t data_e,
                          struct bio *parent_bio)
 {
+        int type = REQ_WRITE | REQ_DISCARD;
         sector_t s = block_to_sectors(tc->pool, data_b);
         sector_t len = block_to_sectors(tc->pool, data_e - data_b);
+        struct bio *bio = NULL;
+        struct blk_plug plug;
+        int ret;
+
+        blk_start_plug(&plug);
+        ret = __blkdev_issue_discard(tc->pool_dev->bdev, s, len,
+                                     GFP_NOWAIT, type, &bio);
+        if (!ret && bio) {
+                bio_chain(bio, parent_bio);
+                submit_bio(type, bio);
+        }
+        blk_finish_plug(&plug);
 
-        return __blkdev_issue_discard_async(tc->pool_dev->bdev, s, len,
-                                            GFP_NOWAIT, 0, parent_bio);
+        return ret;
 }
 
 /*----------------------------------------------------------------*/
@@ -1543,11 +1505,11 @@ static void break_up_discard_bio(struct thin_c *tc, dm_block_t begin, dm_block_t
 
                 /*
                  * The parent bio must not complete before sub discard bios are
-                 * chained to it (see __blkdev_issue_discard_async's bio_chain)!
+                 * chained to it (see issue_discard's bio_chain)!
                  *
                  * This per-mapping bi_remaining increment is paired with
                  * the implicit decrement that occurs via bio_endio() in
-                 * process_prepared_discard_{passdown,no_passdown}.
+                 * process_prepared_discard_passdown().
                  */
                 bio_inc_remaining(bio);
                 if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list))