block: Add BLKROTATIONAL ioctl

Introduce an ioctl which permits applications to query whether a block
device is rotational.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 5 insertions, 0 deletions

diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 7b725020823c..7c668c8a6f95 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -719,6 +719,9 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
         case BLKSECTGET:
                 return compat_put_ushort(arg,
                                          queue_max_sectors(bdev_get_queue(bdev)));
+        case BLKROTATIONAL:
+                return compat_put_ushort(arg,
+                                         !blk_queue_nonrot(bdev_get_queue(bdev)));
         case BLKRASET: /* compatible, but no compat_ptr (!) */
         case BLKFRASET:
                 if (!capable(CAP_SYS_ADMIN))
diff --git a/block/ioctl.c b/block/ioctl.c
index ca939fc1030f..337d207ab14d 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -278,6 +278,8 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
                 return put_uint(arg, bdev_discard_zeroes_data(bdev));
         case BLKSECTGET:
                 return put_ushort(arg, queue_max_sectors(bdev_get_queue(bdev)));
+        case BLKROTATIONAL:
+                return put_ushort(arg, !blk_queue_nonrot(bdev_get_queue(bdev)));
         case BLKRASET:
         case BLKFRASET:
                 if(!capable(CAP_SYS_ADMIN))