linux-kernel - [PATCH v5 17/18] pktcdvd: add compat

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Message-Id: <20190814205521.122180-8-arnd@arndb.de>
Date:   Wed, 14 Aug 2019 22:54:52 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>
Cc:     Arnd Bergmann <arnd@...db.de>, Hannes Reinecke <hare@...e.de>
Subject: [PATCH v5 17/18] pktcdvd: add compat_ioctl handler

pkt_ioctl() implements the generic SCSI_IOCTL_SEND_COMMAND
and some cdrom ioctls by forwarding to the underlying block
device. For compat_ioctl handling, this always takes a
roundtrip through fs/compat_ioctl.c that we should try
to avoid, at least for the compatible commands.

CDROM_SEND_PACKET is an exception here, it requires special
translation in compat_blkdev_driver_ioctl().

CDROM_LAST_WRITTEN has no compat handling at the moment.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/block/pktcdvd.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 024060165afa..b5950b7851b0 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2664,6 +2664,28 @@ static int pkt_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd,
 	return ret;
 }
 
+#ifdef CONFIG_COMPAT
+static int pkt_compat_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	/* compatible */
+	case CDROMEJECT:
+	case CDROMMULTISESSION:
+	case CDROMREADTOCENTRY:
+	case SCSI_IOCTL_SEND_COMMAND:
+		return pkt_ioctl(bdev, mode, cmd, (unsigned long)compat_ptr(arg));
+
+
+	/* FIXME: no handler so far */
+	case CDROM_LAST_WRITTEN:
+	/* handled in compat_blkdev_driver_ioctl */
+	case CDROM_SEND_PACKET:
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+#endif
+
 static unsigned int pkt_check_events(struct gendisk *disk,
 				     unsigned int clearing)
 {
@@ -2685,6 +2707,9 @@ static const struct block_device_operations pktcdvd_ops = {
 	.open =			pkt_open,
 	.release =		pkt_close,
 	.ioctl =		pkt_ioctl,
+#ifdef CONFIG_COMPAT
+	.ioctl =		pkt_compat_ioctl,
+#endif
 	.check_events =		pkt_check_events,
 };
 
-- 
2.20.0