[PATCH 2/4] mtd: rfd_ftl: add discard support

[Sean Young]

I proposed this change 16 years ago before discard was a feature in
the block layer: https://lwn.net/Articles/162776/

Now that the block layer has discard, we can finally merge this change.

Signed-off-by: Sean Young <sean at mess.org>
---
 drivers/mtd/rfd_ftl.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/mtd/rfd_ftl.c b/drivers/mtd/rfd_ftl.c
index 7b243f2b2fa3..7f5f6d247cae 100644
--- a/drivers/mtd/rfd_ftl.c
+++ b/drivers/mtd/rfd_ftl.c
@@ -705,6 +705,34 @@ static int rfd_ftl_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *
 	return rc;
 }
 
+static int rfd_ftl_discardsect(struct mtd_blktrans_dev *dev,
+			       unsigned long sector, unsigned int nr_sects)
+{
+	struct partition *part = (struct partition *)dev;
+	u_long addr;
+	int rc;
+
+	while (nr_sects) {
+		if (sector >= part->sector_count)
+			return -EIO;
+
+		addr = part->sector_map[sector];
+
+		if (addr != -1) {
+			rc = mark_sector_deleted(part, addr);
+			if (rc)
+				return rc;
+
+			part->sector_map[sector] = -1;
+		}
+
+		sector++;
+		nr_sects--;
+	}
+
+	return 0;
+}
+
 static int rfd_ftl_getgeo(struct mtd_blktrans_dev *dev, struct hd_geometry *geo)
 {
 	struct partition *part = (struct partition*)dev;
@@ -786,6 +814,7 @@ static struct mtd_blktrans_ops rfd_ftl_tr = {
 
 	.readsect	= rfd_ftl_readsect,
 	.writesect	= rfd_ftl_writesect,
+	.discard	= rfd_ftl_discardsect,
 	.getgeo		= rfd_ftl_getgeo,
 	.add_mtd	= rfd_ftl_add_mtd,
 	.remove_dev	= rfd_ftl_remove_dev,
-- 
2.31.1