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Commit 1a60a280 authored by Al Viro's avatar Al Viro
Browse files

[PATCH] lock exclusively in collect_mounts() and drop_collected_mounts() 



Taking namespace_sem shared there isn't worth the trouble, especially with
vfsmount ID allocation about to be added.  That way we know that umount_tree(),
copy_tree() and clone_mnt() are _always_ serialized by namespace_sem.
umount_tree() still needs vfsmount_lock (it manipulates hash chains, among
other things), but that's a separate story.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 6d59e7f5

fs/namespace.c

+4 −4
Original line number Diff line number Diff line
@@ -1091,20 +1091,20 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, 
struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry)

{

	struct vfsmount *tree;

	down_read(&namespace_sem);

	down_write(&namespace_sem);

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

	up_read(&namespace_sem);

	up_write(&namespace_sem);

	return tree;

}



void drop_collected_mounts(struct vfsmount *mnt)

{

	LIST_HEAD(umount_list);

	down_read(&namespace_sem);

	down_write(&namespace_sem);

	spin_lock(&vfsmount_lock);

	umount_tree(mnt, 0, &umount_list);

	spin_unlock(&vfsmount_lock);

	up_read(&namespace_sem);

	up_write(&namespace_sem);

	release_mounts(&umount_list);

}