Support 'discard sectors' operation in translation layer support core

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

3 files changed, 19 insertions, 0 deletions

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 9ff007c4962c..681d5aca2af4 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -32,6 +32,14 @@ struct mtd_blkcore_priv {
         spinlock_t queue_lock;
 };
 
+static int blktrans_discard_request(struct request_queue *q,
+                                    struct request *req)
+{
+        req->cmd_type = REQ_TYPE_LINUX_BLOCK;
+        req->cmd[0] = REQ_LB_OP_DISCARD;
+        return 0;
+}
+
 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
                                struct mtd_blktrans_dev *dev,
                                struct request *req)
@@ -44,6 +52,10 @@ static int do_blktrans_request(struct mtd_blktrans_ops *tr,
 
         buf = req->buffer;
 
+        if (req->cmd_type == REQ_TYPE_LINUX_BLOCK &&
+            req->cmd[0] == REQ_LB_OP_DISCARD)
+                return !tr->discard(dev, block, nsect);
+
         if (!blk_fs_request(req))
                 return 0;
 
@@ -367,6 +379,10 @@ int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 
         tr->blkcore_priv->rq->queuedata = tr;
         blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
+        if (tr->discard)
+                blk_queue_set_discard(tr->blkcore_priv->rq,
+                                      blktrans_discard_request);
+
         tr->blkshift = ffs(tr->blksize) - 1;
 
         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 26ececbbebe2..727886d25c4e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -81,6 +81,7 @@ enum {
          */
         REQ_LB_OP_EJECT = 0x40,         /* eject request */
         REQ_LB_OP_FLUSH = 0x41,         /* flush device */
+        REQ_LB_OP_DISCARD = 0x42,       /* discard sectors */
 };
 
 /*
diff --git a/include/linux/mtd/blktrans.h b/include/linux/mtd/blktrans.h
index 310e61606415..8b4aa0523db7 100644
--- a/include/linux/mtd/blktrans.h
+++ b/include/linux/mtd/blktrans.h
@@ -41,6 +41,8 @@ struct mtd_blktrans_ops {
                     unsigned long block, char *buffer);
         int (*writesect)(struct mtd_blktrans_dev *dev,
                      unsigned long block, char *buffer);
+        int (*discard)(struct mtd_blktrans_dev *dev,
+                       unsigned long block, unsigned nr_blocks);
 
         /* Block layer ioctls */
         int (*getgeo)(struct mtd_blktrans_dev *dev, struct hd_geometry *geo);