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Commit 411a938b authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

mnt: Delay removal from the mount hash. 



- Modify __lookup_mnt_hash_last to ignore mounts that have MNT_UMOUNTED set.
- Don't remove mounts from the mount hash table in propogate_umount
- Don't remove mounts from the mount hash table in umount_tree before
  the entire list of mounts to be umounted is selected.
- Remove mounts from the mount hash table as the last thing that
  happens in the case where a mount has a parent in umount_tree.
  Mounts without parents are not hashed (by definition).

This paves the way for delaying removal from the mount hash table even
farther and fixing the MNT_LOCKED vs MNT_DETACH issue.

Cc: stable@vger.kernel.org
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 590ce4bc

fs/namespace.c

+8 −5
Original line number Diff line number Diff line
@@ -632,13 +632,16 @@ struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) 
 */

struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry)

{

	struct mount *p, *res;

	res = p = __lookup_mnt(mnt, dentry);

	struct mount *p, *res = NULL;

	p = __lookup_mnt(mnt, dentry);

	if (!p)

		goto out;

	if (!(p->mnt.mnt_flags & MNT_UMOUNT))

		res = p;

	hlist_for_each_entry_continue(p, mnt_hash) {

		if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry)

			break;

		if (!(p->mnt.mnt_flags & MNT_UMOUNT))

			res = p;

	}

out:
@@ -1336,9 +1339,8 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how) 
		list_move(&p->mnt_list, &tmp_list);

	}



	/* Hide the mounts from lookup_mnt and mnt_mounts */

	/* Hide the mounts from mnt_mounts */

	list_for_each_entry(p, &tmp_list, mnt_list) {

		hlist_del_init_rcu(&p->mnt_hash);

		list_del_init(&p->mnt_child);

	}
@@ -1365,6 +1367,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how) 
			p->mnt_mountpoint = p->mnt.mnt_root;

			p->mnt_parent = p;

			p->mnt_mp = NULL;

			hlist_del_init_rcu(&p->mnt_hash);

		}

		change_mnt_propagation(p, MS_PRIVATE);

	}

fs/pnode.c

+0 −1
Original line number Diff line number Diff line
@@ -383,7 +383,6 @@ static void __propagate_umount(struct mount *mnt) 
		 */

		if (child && list_empty(&child->mnt_mounts)) {

			list_del_init(&child->mnt_child);

			hlist_del_init_rcu(&child->mnt_hash);

			child->mnt.mnt_flags |= MNT_UMOUNT;

			list_move_tail(&child->mnt_list, &mnt->mnt_list);

		}