lightnvm: put block back to gc list on its reclaim fail

BugLink: http://bugs.launchpad.net/bugs/1531539

We delete a block from the gc list before reclaim it, so
put it back to the list on its reclaim fail, otherwise
this block will not get reclaimed and be programmable
in the future.
Signed-off-by: Wenwei Tao <ww.tao0320@gmail.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit d0ca798f)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/lightnvm/rrpc.c

@@ -381,16 +381,26 @@ static void rrpc_block_gc(struct work_struct *work)
 	struct rrpc *rrpc = gcb->rrpc;
 	struct rrpc_block *rblk = gcb->rblk;
 	struct nvm_dev *dev = rrpc->dev;
+	struct nvm_lun *lun = rblk->parent->lun;
+	struct rrpc_lun *rlun = &rrpc->luns[lun->id - rrpc->lun_offset];
 
+	mempool_free(gcb, rrpc->gcb_pool);
 	pr_debug("nvm: block '%lu' being reclaimed\n", rblk->parent->id);
 
 	if (rrpc_move_valid_pages(rrpc, rblk))
-		goto done;
+		goto put_back;
+
+	if (nvm_erase_blk(dev, rblk->parent))
+		goto put_back;
 
-	nvm_erase_blk(dev, rblk->parent);
 	rrpc_put_blk(rrpc, rblk);
-done:
-	mempool_free(gcb, rrpc->gcb_pool);
+
+	return;
+
+put_back:
+	spin_lock(&rlun->lock);
+	list_add_tail(&rblk->prio, &rlun->prio_list);
+	spin_unlock(&rlun->lock);
 }
 
 /* the block with highest number of invalid pages, will be in the beginning