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Commit e819f152 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

mnt: Improve the umount_tree flags 



- Remove the unneeded declaration from pnode.h
- Mark umount_tree static as it has no callers outside of namespace.c
- Define an enumeration of umount_tree's flags.
- Pass umount_tree's flags in by name

This removes the magic numbers 0, 1 and 2 making the code a little
clearer and makes it possible for there to be lazy unmounts that don't
propagate.  Which is what __detach_mounts actually wants for example.

Cc: stable@vger.kernel.org
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent a3b3c562

fs/namespace.c

+16 −15
Original line number Diff line number Diff line
@@ -1317,14 +1317,15 @@ static inline void namespace_lock(void) 
	down_write(&namespace_sem);

}



enum umount_tree_flags {

	UMOUNT_SYNC = 1,

	UMOUNT_PROPAGATE = 2,

};

/*

 * mount_lock must be held

 * namespace_sem must be held for write

 * how = 0 => just this tree, don't propagate

 * how = 1 => propagate; we know that nobody else has reference to any victims

 * how = 2 => lazy umount

 */

void umount_tree(struct mount *mnt, int how)

static void umount_tree(struct mount *mnt, enum umount_tree_flags how)

{

	HLIST_HEAD(tmp_list);

	struct mount *p;
@@ -1337,7 +1338,7 @@ void umount_tree(struct mount *mnt, int how) 
	hlist_for_each_entry(p, &tmp_list, mnt_hash)

		list_del_init(&p->mnt_child);



	if (how)

	if (how & UMOUNT_PROPAGATE)

		propagate_umount(&tmp_list);



	while (!hlist_empty(&tmp_list)) {
@@ -1347,7 +1348,7 @@ void umount_tree(struct mount *mnt, int how) 
		list_del_init(&p->mnt_list);

		__touch_mnt_namespace(p->mnt_ns);

		p->mnt_ns = NULL;

		if (how < 2)

		if (how & UMOUNT_SYNC)

			p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;



		pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted);
@@ -1445,14 +1446,14 @@ static int do_umount(struct mount *mnt, int flags) 


	if (flags & MNT_DETACH) {

		if (!list_empty(&mnt->mnt_list))

			umount_tree(mnt, 2);

			umount_tree(mnt, UMOUNT_PROPAGATE);

		retval = 0;

	} else {

		shrink_submounts(mnt);

		retval = -EBUSY;

		if (!propagate_mount_busy(mnt, 2)) {

			if (!list_empty(&mnt->mnt_list))

				umount_tree(mnt, 1);

				umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);

			retval = 0;

		}

	}
@@ -1484,7 +1485,7 @@ void __detach_mounts(struct dentry *dentry) 
	lock_mount_hash();

	while (!hlist_empty(&mp->m_list)) {

		mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);

		umount_tree(mnt, 2);

		umount_tree(mnt, UMOUNT_PROPAGATE);

	}

	unlock_mount_hash();

	put_mountpoint(mp);
@@ -1646,7 +1647,7 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, 
out:

	if (res) {

		lock_mount_hash();

		umount_tree(res, 0);

		umount_tree(res, UMOUNT_SYNC);

		unlock_mount_hash();

	}

	return q;
@@ -1670,7 +1671,7 @@ void drop_collected_mounts(struct vfsmount *mnt) 
{

	namespace_lock();

	lock_mount_hash();

	umount_tree(real_mount(mnt), 0);

	umount_tree(real_mount(mnt), UMOUNT_SYNC);

	unlock_mount_hash();

	namespace_unlock();

}
@@ -1853,7 +1854,7 @@ static int attach_recursive_mnt(struct mount *source_mnt, 
 out_cleanup_ids:

	while (!hlist_empty(&tree_list)) {

		child = hlist_entry(tree_list.first, struct mount, mnt_hash);

		umount_tree(child, 0);

		umount_tree(child, UMOUNT_SYNC);

	}

	unlock_mount_hash();

	cleanup_group_ids(source_mnt, NULL);
@@ -2033,7 +2034,7 @@ static int do_loopback(struct path *path, const char *old_name, 
	err = graft_tree(mnt, parent, mp);

	if (err) {

		lock_mount_hash();

		umount_tree(mnt, 0);

		umount_tree(mnt, UMOUNT_SYNC);

		unlock_mount_hash();

	}

out2:
@@ -2404,7 +2405,7 @@ void mark_mounts_for_expiry(struct list_head *mounts) 
	while (!list_empty(&graveyard)) {

		mnt = list_first_entry(&graveyard, struct mount, mnt_expire);

		touch_mnt_namespace(mnt->mnt_ns);

		umount_tree(mnt, 1);

		umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);

	}

	unlock_mount_hash();

	namespace_unlock();
@@ -2475,7 +2476,7 @@ static void shrink_submounts(struct mount *mnt) 
			m = list_first_entry(&graveyard, struct mount,

						mnt_expire);

			touch_mnt_namespace(m->mnt_ns);

			umount_tree(m, 1);

			umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC);

		}

	}

}

fs/pnode.h

+0 −1
Original line number Diff line number Diff line
@@ -47,7 +47,6 @@ int get_dominating_id(struct mount *mnt, const struct path *root); 
unsigned int mnt_get_count(struct mount *mnt);

void mnt_set_mountpoint(struct mount *, struct mountpoint *,

			struct mount *);

void umount_tree(struct mount *, int);

struct mount *copy_tree(struct mount *, struct dentry *, int);

bool is_path_reachable(struct mount *, struct dentry *,

			 const struct path *root);