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Subject[PATCH 3/8] vfs: introduce clone_private_mount()
Date
From: Miklos Szeredi <mszeredi@suse.cz>

Overlayfs needs a private clone of the mount, so create a function for
this and export to modules.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
fs/namespace.c | 17 +++++++++++++++++
include/linux/mount.h | 3 +++
2 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 22bfe82..1a95f0e 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1494,6 +1494,23 @@ void drop_collected_mounts(struct vfsmount *mnt)
release_mounts(&umount_list);
}

+struct vfsmount *clone_private_mount(struct path *path)
+{
+ struct vfsmount *mnt;
+
+ if (IS_MNT_UNBINDABLE(path->mnt))
+ return ERR_PTR(-EINVAL);
+
+ down_read(&namespace_sem);
+ mnt = clone_mnt(path->mnt, path->dentry, CL_PRIVATE);
+ up_read(&namespace_sem);
+ if (!mnt)
+ return ERR_PTR(-ENOMEM);
+
+ return mnt;
+}
+EXPORT_SYMBOL_GPL(clone_private_mount);
+
int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
struct vfsmount *root)
{
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 33fe53d..30cd21e 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -100,6 +100,9 @@ extern void mnt_pin(struct vfsmount *mnt);
extern void mnt_unpin(struct vfsmount *mnt);
extern int __mnt_is_readonly(struct vfsmount *mnt);

+struct path;
+extern struct vfsmount *clone_private_mount(struct path *path);
+
extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
const char *name, void *data);

--
1.7.3.4


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