Commit 8aec0809 authored by Al Viro's avatar Al Viro
Browse files

[PATCH] new helpers - collect_mounts() and release_collected_mounts() 



Get a snapshot of a subtree, creating private clones of vfsmounts
for all its components and release such snapshot resp.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 5a190ae6

fs/namespace.c

+21 −1
Original line number Diff line number Diff line
@@ -246,7 +246,7 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, 
			list_add(&mnt->mnt_slave, &old->mnt_slave_list);

			mnt->mnt_master = old;

			CLEAR_MNT_SHARED(mnt);

		} else {

		} else if (!(flag & CL_PRIVATE)) {

			if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))

				list_add(&mnt->mnt_share, &old->mnt_share);

			if (IS_MNT_SLAVE(old))
@@ -746,6 +746,26 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, 
	return NULL;

}



struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry)

{

	struct vfsmount *tree;

	down_read(&namespace_sem);

	tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE);

	up_read(&namespace_sem);

	return tree;

}



void drop_collected_mounts(struct vfsmount *mnt)

{

	LIST_HEAD(umount_list);

	down_read(&namespace_sem);

	spin_lock(&vfsmount_lock);

	umount_tree(mnt, 0, &umount_list);

	spin_unlock(&vfsmount_lock);

	up_read(&namespace_sem);

	release_mounts(&umount_list);

}



/*

 *  @source_mnt : mount tree to be attached

 *  @nd         : place the mount tree @source_mnt is attached

fs/pnode.h

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#define CL_COPY_ALL 		0x04

#define CL_MAKE_SHARED 		0x08

#define CL_PROPAGATION 		0x10

#define CL_PRIVATE 		0x20



static inline void set_mnt_shared(struct vfsmount *mnt)

{

include/linux/fs.h

+2 −0
Original line number Diff line number Diff line
@@ -1470,6 +1470,8 @@ extern long do_mount(char *, char *, char *, unsigned long, void *); 
extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);

extern void mnt_set_mountpoint(struct vfsmount *, struct dentry *,

				  struct vfsmount *);

extern struct vfsmount *collect_mounts(struct vfsmount *, struct dentry *);

extern void drop_collected_mounts(struct vfsmount *);



extern int vfs_statfs(struct dentry *, struct kstatfs *);