[PATCH] dm: support ioctls on mapped devices: fix with fake file

The new ioctl code passes the wrong file pointer to the underlying device.
No file pointer is available so make a temporary fake one.

ioctl_by_bdev() does set_fs(KERNEL_DS) so it's for ioctls originating
within the kernel and unsuitable here.  We are processing ioctls that
originated in userspace and mapping them to different devices.  Fixing the
existing callers that pass a NULL file struct and consolidating the
fake_file users are separate matters to solve in later patches.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 2a6bad4..0023490 100644 (file)
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -104,8 +104,14 @@ static int linear_ioctl(struct dm_target *ti, struct inode *inode,
 {
        struct linear_c *lc = (struct linear_c *) ti->private;
        struct block_device *bdev = lc->dev->bdev;
+       struct file fake_file = {};
+       struct dentry fake_dentry = {};
 
-       return blkdev_driver_ioctl(bdev->bd_inode, filp, bdev->bd_disk, cmd, arg);
+       fake_file.f_mode = lc->dev->mode;
+       fake_file.f_dentry = &fake_dentry;
+       fake_dentry.d_inode = bdev->bd_inode;
+
+       return blkdev_driver_ioctl(bdev->bd_inode, &fake_file, bdev->bd_disk, cmd, arg);
 }
 
 static struct target_type linear_target = {

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index dcfbf83..fb9582a 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1273,15 +1273,22 @@ static int multipath_ioctl(struct dm_target *ti, struct inode *inode,
        struct multipath *m = (struct multipath *) ti->private;
        struct block_device *bdev = NULL;
        unsigned long flags;
+       struct file fake_file = {};
+       struct dentry fake_dentry = {};
        int r = 0;
 
+       fake_file.f_dentry = &fake_dentry;
+
        spin_lock_irqsave(&m->lock, flags);
 
        if (!m->current_pgpath)
                __choose_pgpath(m);
 
-       if (m->current_pgpath)
+       if (m->current_pgpath) {
                bdev = m->current_pgpath->path.dev->bdev;
+               fake_dentry.d_inode = bdev->bd_inode;
+               fake_file.f_mode = m->current_pgpath->path.dev->mode;
+       }
 
        if (m->queue_io)
                r = -EAGAIN;
@@ -1290,8 +1297,8 @@ static int multipath_ioctl(struct dm_target *ti, struct inode *inode,
 
        spin_unlock_irqrestore(&m->lock, flags);
 
-       return r ? : blkdev_driver_ioctl(bdev->bd_inode, filp, bdev->bd_disk,
-                    cmd, arg);
+       return r ? : blkdev_driver_ioctl(bdev->bd_inode, &fake_file,
+                                        bdev->bd_disk, cmd, arg);
 }
 
 /*-----------------------------------------------------------------