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

[Mike Waychison]

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);
 	}
 	return -ENOTTY;
 }
Index: linux-2.6.9-quilt/fs/namespace.c
===================================================================
--- linux-2.6.9-quilt.orig/fs/namespace.c	2004-10-22 17:17:40.738270984 -0400
+++ linux-2.6.9-quilt/fs/namespace.c	2004-10-22 17:17:41.368175224 -0400
@@ -601,7 +601,7 @@ static void umount_tree(struct vfsmount 
 	spin_lock(&vfsmount_lock);
 }
 
-static int do_umount(struct vfsmount *mnt, int flags)
+int do_umount(struct vfsmount *mnt, int flags)
 {
 	struct super_block * sb = mnt->mnt_sb;
 	int retval;
Index: linux-2.6.9-quilt/include/linux/fs.h
===================================================================
--- linux-2.6.9-quilt.orig/include/linux/fs.h	2004-10-22 17:17:40.739270832 -0400
+++ linux-2.6.9-quilt/include/linux/fs.h	2004-10-22 17:17:41.369175072 -0400
@@ -214,7 +214,10 @@ extern int leases_enable, dir_notify_ena
 #define FIBMAP	   _IO(0x00,1)	/* bmap access */
 #define FIGETBSZ   _IO(0x00,2)	/* get the block size used for bmap */
 
-#define MOUNTFD_IOC_GETDIRFD _IO('p', 0xa0)
+#define MOUNTFD_IOC_GETDIRFD      _IO('p', 0xa0)
+#define MOUNTFD_IOC_UNMOUNT       _IO('p', 0xa1)
+#define MOUNTFD_IOC_DETACH        _IO('p', 0xa2)
+#define MOUNTFD_IOC_FORCEDUNMOUNT _IO('p', 0xa3)
 
 #ifdef __KERNEL__
 

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