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Commit 7c4b93d8 authored by Al Viro's avatar Al Viro
Browse files

[PATCH] count ghost references to vfsmounts 



make propagate_mount_busy() exclude references from the vfsmounts
that had been isolated by umount_tree() and are just waiting for
release_mounts() to dispose of their ->mnt_parent/->mnt_mountpoint.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 1a390689

fs/namespace.c

+4 −1
Original line number Diff line number Diff line
@@ -548,6 +548,7 @@ void release_mounts(struct list_head *head) 
			m = mnt->mnt_parent;

			mnt->mnt_mountpoint = mnt->mnt_root;

			mnt->mnt_parent = mnt;

			m->mnt_ghosts--;

			spin_unlock(&vfsmount_lock);

			dput(dentry);

			mntput(m);
@@ -572,8 +573,10 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) 
		__touch_mnt_namespace(p->mnt_ns);

		p->mnt_ns = NULL;

		list_del_init(&p->mnt_child);

		if (p->mnt_parent != p)

		if (p->mnt_parent != p) {

			p->mnt_parent->mnt_ghosts++;

			p->mnt_mountpoint->d_mounted--;

		}

		change_mnt_propagation(p, MS_PRIVATE);

	}

}

fs/pnode.c

+1 −1
Original line number Diff line number Diff line
@@ -225,7 +225,7 @@ int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry, 
 */

static inline int do_refcount_check(struct vfsmount *mnt, int count)

{

	int mycount = atomic_read(&mnt->mnt_count);

	int mycount = atomic_read(&mnt->mnt_count) - mnt->mnt_ghosts;

	return (mycount > count);

}

include/linux/mount.h

+1 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ struct vfsmount { 
	atomic_t mnt_count;

	int mnt_expiry_mark;		/* true if marked for expiry */

	int mnt_pinned;

	int mnt_ghosts;

};



static inline struct vfsmount *mntget(struct vfsmount *mnt)