dm ioctl: use nonseekable_open

The dm control device does not implement read/write, so it has no use for
seeking.  Using no_llseek prevents falling back to default_llseek, which
requires the BKL.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index feb64d65fbfb..3fd8f0e169e7 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1602,6 +1602,7 @@ static long dm_compat_ctl_ioctl(struct file *file, uint command, ulong u)
 #endif
 
 static const struct file_operations _ctl_fops = {
+        .open = nonseekable_open,
         .unlocked_ioctl  = dm_ctl_ioctl,
         .compat_ioctl = dm_compat_ctl_ioctl,
         .owner   = THIS_MODULE,