md: linear supports TRIM

This makes md linear support TRIM.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 92c64d162a92457c468e46f8cc15472febf0cfc7..21014836bdbf2286eba4fd02effbc4efcd9db625 100644 (file)
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -138,6 +138,7 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
        struct linear_conf *conf;
        struct md_rdev *rdev;
        int i, cnt;
+       bool discard_supported = false;
 
        conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
                        GFP_KERNEL);
@@ -171,6 +172,8 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
                conf->array_sectors += rdev->sectors;
                cnt++;
 
+               if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
+                       discard_supported = true;
        }
        if (cnt != raid_disks) {
                printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
@@ -178,6 +181,11 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
                goto out;
        }
 
+       if (!discard_supported)
+               queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
+       else
+               queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
+
        /*
         * Here we calculate the device offsets.
         */
@@ -331,6 +339,14 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio)
        bio->bi_sector = bio->bi_sector - start_sector
                + tmp_dev->rdev->data_offset;
        rcu_read_unlock();
+
+       if (unlikely((bio->bi_rw & REQ_DISCARD) &&
+                    !blk_queue_discard(bdev_get_queue(bio->bi_bdev)))) {
+               /* Just ignore it */
+               bio_endio(bio, 0);
+               return;
+       }
+
        generic_make_request(bio);
 }