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Commit 36341f64 authored by Ram Pai's avatar Ram Pai Committed by Linus Torvalds
Browse files

[PATCH] mount expiry fixes 



 - clean up the ugliness in may_umount_tree()

 - fix a bug in do_loopback().  after cloning a tree, do_loopback()
   unlinks only the topmost mount of the cloned tree, leaving behind the
   children mounts on their corresponding expiry list.

Signed-off-by: default avatarRam Pai <linuxram@us.ibm.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 70fbcdf4

fs/namespace.c

+22 −42
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ 


extern int __init init_rootfs(void);



#define CL_EXPIRE 	0x01



#ifdef CONFIG_SYSFS

extern int __init sysfs_init(void);

#else
@@ -165,7 +167,8 @@ static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) 
	return list_entry(next, struct vfsmount, mnt_child);

}



static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root)

static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,

					int flag)

{

	struct super_block *sb = old->mnt_sb;

	struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
@@ -181,11 +184,13 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root) 


		/* stick the duplicate mount on the same expiry list

		 * as the original if that was on one */

		if (flag & CL_EXPIRE) {

			spin_lock(&vfsmount_lock);

			if (!list_empty(&old->mnt_expire))

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

			spin_unlock(&vfsmount_lock);

		}

	}

	return mnt;

}
@@ -331,36 +336,14 @@ struct seq_operations mounts_op = { 
 */

int may_umount_tree(struct vfsmount *mnt)

{

	struct list_head *next;

	struct vfsmount *this_parent = mnt;

	int actual_refs;

	int minimum_refs;

	int actual_refs = 0;

	int minimum_refs = 0;

	struct vfsmount *p;



	spin_lock(&vfsmount_lock);

	actual_refs = atomic_read(&mnt->mnt_count);

	minimum_refs = 2;

repeat:

	next = this_parent->mnt_mounts.next;

resume:

	while (next != &this_parent->mnt_mounts) {

		struct vfsmount *p =

		    list_entry(next, struct vfsmount, mnt_child);



		next = next->next;



	for (p = mnt; p; p = next_mnt(p, mnt)) {

		actual_refs += atomic_read(&p->mnt_count);

		minimum_refs += 2;



		if (!list_empty(&p->mnt_mounts)) {

			this_parent = p;

			goto repeat;

		}

	}



	if (this_parent != mnt) {

		next = this_parent->mnt_child.next;

		this_parent = this_parent->mnt_parent;

		goto resume;

	}

	spin_unlock(&vfsmount_lock);
@@ -596,12 +579,13 @@ static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) 
	}

}



static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry)

static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,

					int flag)

{

	struct vfsmount *res, *p, *q, *r, *s;

	struct nameidata nd;



	res = q = clone_mnt(mnt, dentry);

	res = q = clone_mnt(mnt, dentry, flag);

	if (!q)

		goto Enomem;

	q->mnt_mountpoint = mnt->mnt_mountpoint;
@@ -619,7 +603,7 @@ static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry) 
			p = s;

			nd.mnt = q;

			nd.dentry = p->mnt_mountpoint;

			q = clone_mnt(p, p->mnt_root);

			q = clone_mnt(p, p->mnt_root, flag);

			if (!q)

				goto Enomem;

			spin_lock(&vfsmount_lock);
@@ -701,18 +685,13 @@ static int do_loopback(struct nameidata *nd, char *old_name, int recurse) 


	err = -ENOMEM;

	if (recurse)

		mnt = copy_tree(old_nd.mnt, old_nd.dentry);

		mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0);

	else

		mnt = clone_mnt(old_nd.mnt, old_nd.dentry);

		mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0);



	if (!mnt)

		goto out;



	/* stop bind mounts from expiring */

	spin_lock(&vfsmount_lock);

	list_del_init(&mnt->mnt_expire);

	spin_unlock(&vfsmount_lock);



	err = graft_tree(mnt, nd);

	if (err) {

		LIST_HEAD(umount_list);
@@ -1155,7 +1134,8 @@ int copy_namespace(int flags, struct task_struct *tsk) 


	down_write(&tsk->namespace->sem);

	/* First pass: copy the tree topology */

	new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root);

	new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root,

					CL_EXPIRE);

	if (!new_ns->root) {

		up_write(&tsk->namespace->sem);

		kfree(new_ns);