1 files changed, 21 insertions, 2 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 611b5f79761..05c557e8f86 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -781,7 +781,12 @@ static void flush_pending_writes(struct r1conf *conf)
                 while (bio) { /* submit pending writes */
                         struct bio *next = bio->bi_next;
                         bio->bi_next = NULL;
-                        generic_make_request(bio);
+                        if (unlikely((bio->bi_rw & REQ_DISCARD) &&
+                            !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
+                                /* Just ignore it */
+                                bio_endio(bio, 0);
+                        else
+                                generic_make_request(bio);
                         bio = next;
                 }
         } else
@@ -994,6 +999,8 @@ static void make_request(struct mddev *mddev, struct bio * bio)
         const int rw = bio_data_dir(bio);
         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
         const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
+        const unsigned long do_discard = (bio->bi_rw
+                                          & (REQ_DISCARD | REQ_SECURE));
         struct md_rdev *blocked_rdev;
         struct blk_plug_cb *cb;
         struct raid1_plug_cb *plug = NULL;
@@ -1295,7 +1302,7 @@ read_again:
                                    conf->mirrors[i].rdev->data_offset);
                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
                 mbio->bi_end_io = raid1_end_write_request;
-                mbio->bi_rw = WRITE | do_flush_fua | do_sync;
+                mbio->bi_rw = WRITE | do_flush_fua | do_sync | do_discard;
                 mbio->bi_private = r1_bio;
 
                 atomic_inc(&r1_bio->remaining);
@@ -1549,6 +1556,8 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
                 clear_bit(Unmerged, &rdev->flags);
         }
         md_integrity_add_rdev(rdev, mddev);
+        if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
+                queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
         print_conf(conf);
         return err;
 }
@@ -2783,6 +2792,7 @@ static int run(struct mddev *mddev)
         int i;
         struct md_rdev *rdev;
         int ret;
+        bool discard_supported = false;
 
         if (mddev->level != 1) {
                 printk(KERN_ERR "md/raid1:%s: raid level not set to mirroring (%d)\n",
@@ -2812,6 +2822,8 @@ static int run(struct mddev *mddev)
                         continue;
                 disk_stack_limits(mddev->gendisk, rdev->bdev,
                                   rdev->data_offset << 9);
+                if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
+                        discard_supported = true;
         }
 
         mddev->degraded = 0;
@@ -2846,6 +2858,13 @@ static int run(struct mddev *mddev)
                 mddev->queue->backing_dev_info.congested_fn = raid1_congested;
                 mddev->queue->backing_dev_info.congested_data = mddev;
                 blk_queue_merge_bvec(mddev->queue, raid1_mergeable_bvec);
+
+                if (discard_supported)
+                        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
+                                                mddev->queue);
+                else
+                        queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
+                                                  mddev->queue);
         }
 
         ret =  md_integrity_register(mddev);