Re: [PATCH 15/28] VFS: Mountpoint file descriptor umount support

From: Christoph Hellwig
Date: Tue Oct 26 2004 - 05:31:41 EST


On Mon, Oct 25, 2004 at 10:46:09AM -0400, Mike Waychison wrote:
> This patch adds functionality to mountfd so that a user can perform the
> various types of umount (forced umount, not-busy umount, lazy-umount).
>
> Signed-off-by: Mike Waychison <michael.waychison@xxxxxxx>
> ---
>
> fs/mountfd.c | 20 ++++++++++++++++++++
> fs/namespace.c | 2 +-
> include/linux/fs.h | 5 ++++-
> 3 files changed, 25 insertions(+), 2 deletions(-)
>
> Index: linux-2.6.9-quilt/fs/mountfd.c
> ===================================================================
> --- linux-2.6.9-quilt.orig/fs/mountfd.c 2004-10-22 17:17:40.736271288 -0400
> +++ linux-2.6.9-quilt/fs/mountfd.c 2004-10-22 17:17:41.367175376 -0400
> @@ -11,6 +11,8 @@
>
> #define VFSMOUNT(filp) ((struct vfsmount *)((filp)->private_data))
>
> +extern int do_umount(struct vfsmount *mnt, int flags);
> +
> static struct vfsmount *mfdfs_mnt;
>
> static void mfdfs_read_inode(struct inode *inode);
> @@ -72,6 +74,18 @@ static int mfd_release(struct inode *ino
> return 0;
> }
>
> +static long mfd_umount(struct file *mountfilp, int flags)
> +{
> + struct vfsmount *mnt;
> + int error;
> +
> + mnt = mntget(VFSMOUNT(mountfilp));
> +
> + error = do_umount(mnt, flags);
> +
> + return error;
> +}
> +
> static int mfd_ioctl(struct inode *inode, struct file *filp,
> unsigned int cmd, unsigned long arg);
> static struct file_operations mfd_file_ops = {
> @@ -243,6 +257,12 @@ static int mfd_ioctl(struct inode *inode
> switch (cmd) {
> case MOUNTFD_IOC_GETDIRFD:
> return mfd_getdirfd(filp);
> + case MOUNTFD_IOC_DETACH:
> + return mfd_umount(filp, MNT_DETACH);
> + case MOUNTFD_IOC_UNMOUNT:
> + return mfd_umount(filp, 0);
> + case MOUNTFD_IOC_FORCEDUNMOUNT:
> + return mfd_umount(filp, MNT_FORCE);

Urgg, you don't want to add gazillions of strange ioctls, do you?

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