diff --git a/fs/namespace.c b/fs/namespace.c
index 2e10cb1..de402eb 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -11,6 +11,8 @@
 #include <linux/syscalls.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/percpu.h>
 #include <linux/smp_lock.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -38,12 +40,10 @@
 #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head))
 #define HASH_SIZE (1UL << HASH_SHIFT)
 
-/* spinlock for vfsmount related operations, inplace of dcache_lock */
-__cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
-
 static int event;
 static DEFINE_IDA(mnt_id_ida);
 static DEFINE_IDA(mnt_group_ida);
+static DEFINE_SPINLOCK(mnt_id_lock);
 static int mnt_id_start = 0;
 static int mnt_group_start = 1;
 
@@ -55,6 +55,16 @@
 struct kobject *fs_kobj;
 EXPORT_SYMBOL_GPL(fs_kobj);
 
+/*
+ * vfsmount lock may be taken for read to prevent changes to the
+ * vfsmount hash, ie. during mountpoint lookups or walking back
+ * up the tree.
+ *
+ * It should be taken for write in all cases where the vfsmount
+ * tree or hash is modified or when a vfsmount structure is modified.
+ */
+DEFINE_BRLOCK(vfsmount_lock);
+
 static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
 {
 	unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
@@ -65,18 +75,21 @@
 
 #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16)
 
-/* allocation is serialized by namespace_sem */
+/*
+ * allocation is serialized by namespace_sem, but we need the spinlock to
+ * serialize with freeing.
+ */
 static int mnt_alloc_id(struct vfsmount *mnt)
 {
 	int res;
 
 retry:
 	ida_pre_get(&mnt_id_ida, GFP_KERNEL);
-	spin_lock(&vfsmount_lock);
+	spin_lock(&mnt_id_lock);
 	res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id);
 	if (!res)
 		mnt_id_start = mnt->mnt_id + 1;
-	spin_unlock(&vfsmount_lock);
+	spin_unlock(&mnt_id_lock);
 	if (res == -EAGAIN)
 		goto retry;
 
@@ -86,11 +99,11 @@
 static void mnt_free_id(struct vfsmount *mnt)
 {
 	int id = mnt->mnt_id;
-	spin_lock(&vfsmount_lock);
+	spin_lock(&mnt_id_lock);
 	ida_remove(&mnt_id_ida, id);
 	if (mnt_id_start > id)
 		mnt_id_start = id;
-	spin_unlock(&vfsmount_lock);
+	spin_unlock(&mnt_id_lock);
 }
 
 /*
@@ -348,7 +361,7 @@
 {
 	int ret = 0;
 
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	mnt->mnt_flags |= MNT_WRITE_HOLD;
 	/*
 	 * After storing MNT_WRITE_HOLD, we'll read the counters. This store
@@ -382,15 +395,15 @@
 	 */
 	smp_wmb();
 	mnt->mnt_flags &= ~MNT_WRITE_HOLD;
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 	return ret;
 }
 
 static void __mnt_unmake_readonly(struct vfsmount *mnt)
 {
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	mnt->mnt_flags &= ~MNT_READONLY;
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 }
 
 void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
@@ -414,6 +427,7 @@
 /*
  * find the first or last mount at @dentry on vfsmount @mnt depending on
  * @dir. If @dir is set return the first mount else return the last mount.
+ * vfsmount_lock must be held for read or write.
  */
 struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry,
 			      int dir)
@@ -443,10 +457,11 @@
 struct vfsmount *lookup_mnt(struct path *path)
 {
 	struct vfsmount *child_mnt;
-	spin_lock(&vfsmount_lock);
+
+	br_read_lock(vfsmount_lock);
 	if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1)))
 		mntget(child_mnt);
-	spin_unlock(&vfsmount_lock);
+	br_read_unlock(vfsmount_lock);
 	return child_mnt;
 }
 
@@ -455,6 +470,9 @@
 	return mnt->mnt_ns == current->nsproxy->mnt_ns;
 }
 
+/*
+ * vfsmount lock must be held for write
+ */
 static void touch_mnt_namespace(struct mnt_namespace *ns)
 {
 	if (ns) {
@@ -463,6 +481,9 @@
 	}
 }
 
+/*
+ * vfsmount lock must be held for write
+ */
 static void __touch_mnt_namespace(struct mnt_namespace *ns)
 {
 	if (ns && ns->event != event) {
@@ -471,6 +492,9 @@
 	}
 }
 
+/*
+ * vfsmount lock must be held for write
+ */
 static void detach_mnt(struct vfsmount *mnt, struct path *old_path)
 {
 	old_path->dentry = mnt->mnt_mountpoint;
@@ -482,6 +506,9 @@
 	old_path->dentry->d_mounted--;
 }
 
+/*
+ * vfsmount lock must be held for write
+ */
 void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
 			struct vfsmount *child_mnt)
 {
@@ -490,6 +517,9 @@
 	dentry->d_mounted++;
 }
 
+/*
+ * vfsmount lock must be held for write
+ */
 static void attach_mnt(struct vfsmount *mnt, struct path *path)
 {
 	mnt_set_mountpoint(path->mnt, path->dentry, mnt);
@@ -499,7 +529,7 @@
 }
 
 /*
- * the caller must hold vfsmount_lock
+ * vfsmount lock must be held for write
  */
 static void commit_tree(struct vfsmount *mnt)
 {
@@ -623,39 +653,43 @@
 void mntput_no_expire(struct vfsmount *mnt)
 {
 repeat:
-	if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) {
-		if (likely(!mnt->mnt_pinned)) {
-			spin_unlock(&vfsmount_lock);
-			__mntput(mnt);
-			return;
-		}
-		atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
-		mnt->mnt_pinned = 0;
-		spin_unlock(&vfsmount_lock);
-		acct_auto_close_mnt(mnt);
-		goto repeat;
+	if (atomic_add_unless(&mnt->mnt_count, -1, 1))
+		return;
+	br_write_lock(vfsmount_lock);
+	if (!atomic_dec_and_test(&mnt->mnt_count)) {
+		br_write_unlock(vfsmount_lock);
+		return;
 	}
+	if (likely(!mnt->mnt_pinned)) {
+		br_write_unlock(vfsmount_lock);
+		__mntput(mnt);
+		return;
+	}
+	atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
+	mnt->mnt_pinned = 0;
+	br_write_unlock(vfsmount_lock);
+	acct_auto_close_mnt(mnt);
+	goto repeat;
 }
-
 EXPORT_SYMBOL(mntput_no_expire);
 
 void mnt_pin(struct vfsmount *mnt)
 {
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	mnt->mnt_pinned++;
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 }
 
 EXPORT_SYMBOL(mnt_pin);
 
 void mnt_unpin(struct vfsmount *mnt)
 {
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	if (mnt->mnt_pinned) {
 		atomic_inc(&mnt->mnt_count);
 		mnt->mnt_pinned--;
 	}
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 }
 
 EXPORT_SYMBOL(mnt_unpin);
@@ -746,12 +780,12 @@
 	struct mnt_namespace *ns = p->ns;
 	int res = 0;
 
-	spin_lock(&vfsmount_lock);
+	br_read_lock(vfsmount_lock);
 	if (p->event != ns->event) {
 		p->event = ns->event;
 		res = 1;
 	}
-	spin_unlock(&vfsmount_lock);
+	br_read_unlock(vfsmount_lock);
 
 	return res;
 }
@@ -952,12 +986,12 @@
 	int minimum_refs = 0;
 	struct vfsmount *p;
 
-	spin_lock(&vfsmount_lock);
+	br_read_lock(vfsmount_lock);
 	for (p = mnt; p; p = next_mnt(p, mnt)) {
 		actual_refs += atomic_read(&p->mnt_count);
 		minimum_refs += 2;
 	}
-	spin_unlock(&vfsmount_lock);
+	br_read_unlock(vfsmount_lock);
 
 	if (actual_refs > minimum_refs)
 		return 0;
@@ -984,10 +1018,10 @@
 {
 	int ret = 1;
 	down_read(&namespace_sem);
-	spin_lock(&vfsmount_lock);
+	br_read_lock(vfsmount_lock);
 	if (propagate_mount_busy(mnt, 2))
 		ret = 0;
-	spin_unlock(&vfsmount_lock);
+	br_read_unlock(vfsmount_lock);
 	up_read(&namespace_sem);
 	return ret;
 }
@@ -1003,13 +1037,14 @@
 		if (mnt->mnt_parent != mnt) {
 			struct dentry *dentry;
 			struct vfsmount *m;
-			spin_lock(&vfsmount_lock);
+
+			br_write_lock(vfsmount_lock);
 			dentry = mnt->mnt_mountpoint;
 			m = mnt->mnt_parent;
 			mnt->mnt_mountpoint = mnt->mnt_root;
 			mnt->mnt_parent = mnt;
 			m->mnt_ghosts--;
-			spin_unlock(&vfsmount_lock);
+			br_write_unlock(vfsmount_lock);
 			dput(dentry);
 			mntput(m);
 		}
@@ -1017,6 +1052,10 @@
 	}
 }
 
+/*
+ * vfsmount lock must be held for write
+ * namespace_sem must be held for write
+ */
 void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
 {
 	struct vfsmount *p;
@@ -1107,7 +1146,7 @@
 	}
 
 	down_write(&namespace_sem);
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	event++;
 
 	if (!(flags & MNT_DETACH))
@@ -1119,7 +1158,7 @@
 			umount_tree(mnt, 1, &umount_list);
 		retval = 0;
 	}
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 	up_write(&namespace_sem);
 	release_mounts(&umount_list);
 	return retval;
@@ -1231,19 +1270,19 @@
 			q = clone_mnt(p, p->mnt_root, flag);
 			if (!q)
 				goto Enomem;
-			spin_lock(&vfsmount_lock);
+			br_write_lock(vfsmount_lock);
 			list_add_tail(&q->mnt_list, &res->mnt_list);
 			attach_mnt(q, &path);
-			spin_unlock(&vfsmount_lock);
+			br_write_unlock(vfsmount_lock);
 		}
 	}
 	return res;
 Enomem:
 	if (res) {
 		LIST_HEAD(umount_list);
-		spin_lock(&vfsmount_lock);
+		br_write_lock(vfsmount_lock);
 		umount_tree(res, 0, &umount_list);
-		spin_unlock(&vfsmount_lock);
+		br_write_unlock(vfsmount_lock);
 		release_mounts(&umount_list);
 	}
 	return NULL;
@@ -1262,9 +1301,9 @@
 {
 	LIST_HEAD(umount_list);
 	down_write(&namespace_sem);
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	umount_tree(mnt, 0, &umount_list);
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 	up_write(&namespace_sem);
 	release_mounts(&umount_list);
 }
@@ -1392,7 +1431,7 @@
 	if (err)
 		goto out_cleanup_ids;
 
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 
 	if (IS_MNT_SHARED(dest_mnt)) {
 		for (p = source_mnt; p; p = next_mnt(p, source_mnt))
@@ -1411,7 +1450,8 @@
 		list_del_init(&child->mnt_hash);
 		commit_tree(child);
 	}
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
+
 	return 0;
 
  out_cleanup_ids:
@@ -1466,10 +1506,10 @@
 			goto out_unlock;
 	}
 
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
 		change_mnt_propagation(m, type);
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 
  out_unlock:
 	up_write(&namespace_sem);
@@ -1513,9 +1553,10 @@
 	err = graft_tree(mnt, path);
 	if (err) {
 		LIST_HEAD(umount_list);
-		spin_lock(&vfsmount_lock);
+
+		br_write_lock(vfsmount_lock);
 		umount_tree(mnt, 0, &umount_list);
-		spin_unlock(&vfsmount_lock);
+		br_write_unlock(vfsmount_lock);
 		release_mounts(&umount_list);
 	}
 
@@ -1568,16 +1609,16 @@
 	else
 		err = do_remount_sb(sb, flags, data, 0);
 	if (!err) {
-		spin_lock(&vfsmount_lock);
+		br_write_lock(vfsmount_lock);
 		mnt_flags |= path->mnt->mnt_flags & MNT_PROPAGATION_MASK;
 		path->mnt->mnt_flags = mnt_flags;
-		spin_unlock(&vfsmount_lock);
+		br_write_unlock(vfsmount_lock);
 	}
 	up_write(&sb->s_umount);
 	if (!err) {
-		spin_lock(&vfsmount_lock);
+		br_write_lock(vfsmount_lock);
 		touch_mnt_namespace(path->mnt->mnt_ns);
-		spin_unlock(&vfsmount_lock);
+		br_write_unlock(vfsmount_lock);
 	}
 	return err;
 }
@@ -1754,7 +1795,7 @@
 		return;
 
 	down_write(&namespace_sem);
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 
 	/* extract from the expiration list every vfsmount that matches the
 	 * following criteria:
@@ -1773,7 +1814,7 @@
 		touch_mnt_namespace(mnt->mnt_ns);
 		umount_tree(mnt, 1, &umounts);
 	}
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 	up_write(&namespace_sem);
 
 	release_mounts(&umounts);
@@ -1830,6 +1871,8 @@
 /*
  * process a list of expirable mountpoints with the intent of discarding any
  * submounts of a specific parent mountpoint
+ *
+ * vfsmount_lock must be held for write
  */
 static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts)
 {
@@ -2048,9 +2091,9 @@
 		kfree(new_ns);
 		return ERR_PTR(-ENOMEM);
 	}
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 
 	/*
 	 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
@@ -2244,7 +2287,7 @@
 		goto out2; /* not attached */
 	/* make sure we can reach put_old from new_root */
 	tmp = old.mnt;
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	if (tmp != new.mnt) {
 		for (;;) {
 			if (tmp->mnt_parent == tmp)
@@ -2264,7 +2307,7 @@
 	/* mount new_root on / */
 	attach_mnt(new.mnt, &root_parent);
 	touch_mnt_namespace(current->nsproxy->mnt_ns);
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 	chroot_fs_refs(&root, &new);
 	error = 0;
 	path_put(&root_parent);
@@ -2279,7 +2322,7 @@
 out0:
 	return error;
 out3:
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 	goto out2;
 }
 
@@ -2326,6 +2369,8 @@
 	for (u = 0; u < HASH_SIZE; u++)
 		INIT_LIST_HEAD(&mount_hashtable[u]);
 
+	br_lock_init(vfsmount_lock);
+
 	err = sysfs_init();
 	if (err)
 		printk(KERN_WARNING "%s: sysfs_init error: %d\n",
@@ -2344,9 +2389,9 @@
 	if (!atomic_dec_and_test(&ns->count))
 		return;
 	down_write(&namespace_sem);
-	spin_lock(&vfsmount_lock);
+	br_write_lock(vfsmount_lock);
 	umount_tree(ns->root, 0, &umount_list);
-	spin_unlock(&vfsmount_lock);
+	br_write_unlock(vfsmount_lock);
 	up_write(&namespace_sem);
 	release_mounts(&umount_list);
 	kfree(ns);