13 files changed, 283 insertions, 98 deletions

diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index 5a24f40bb48e..f099b82703d8 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -1542,7 +1542,7 @@ pfm_exit_smpl_buffer(pfm_buffer_fmt_t *fmt)
  * any operations on the root directory. However, we need a non-trivial
  * d_name - pfm: will go nicely and kill the special-casing in procfs.
  */
-static struct vfsmount *pfmfs_mnt;
+static struct vfsmount *pfmfs_mnt __read_mostly;
 
 static int __init
 init_pfm_fs(void)
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 4759d827e8c7..f511dd15fd31 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -1201,7 +1201,7 @@ err_unregister_chdev:
 static void __exit cleanup_mtdchar(void)
 {
         unregister_mtd_user(&mtdchar_notifier);
-        mntput(mtd_inode_mnt);
+        mntput_long(mtd_inode_mnt);
         unregister_filesystem(&mtd_inodefs_type);
         __unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
 }
diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 9d92b33da8a0..5fd38112a6ca 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -232,7 +232,7 @@ static int __init anon_inode_init(void)
         return 0;
 
 err_mntput:
-        mntput(anon_inode_mnt);
+        mntput_long(anon_inode_mnt);
 err_unregister_filesystem:
         unregister_filesystem(&anon_inode_fs_type);
 err_exit:
diff --git a/fs/fs_struct.c b/fs/fs_struct.c
index 60b8531f41c5..68ca487bedb1 100644
--- a/fs/fs_struct.c
+++ b/fs/fs_struct.c
@@ -17,11 +17,11 @@ void set_fs_root(struct fs_struct *fs, struct path *path)
         write_seqcount_begin(&fs->seq);
         old_root = fs->root;
         fs->root = *path;
-        path_get(path);
+        path_get_long(path);
         write_seqcount_end(&fs->seq);
         spin_unlock(&fs->lock);
         if (old_root.dentry)
-                path_put(&old_root);
+                path_put_long(&old_root);
 }
 
 /*
@@ -36,12 +36,12 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
         write_seqcount_begin(&fs->seq);
         old_pwd = fs->pwd;
         fs->pwd = *path;
-        path_get(path);
+        path_get_long(path);
         write_seqcount_end(&fs->seq);
         spin_unlock(&fs->lock);
 
         if (old_pwd.dentry)
-                path_put(&old_pwd);
+                path_put_long(&old_pwd);
 }
 
 void chroot_fs_refs(struct path *old_root, struct path *new_root)
@@ -59,13 +59,13 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
                         write_seqcount_begin(&fs->seq);
                         if (fs->root.dentry == old_root->dentry
                             && fs->root.mnt == old_root->mnt) {
-                                path_get(new_root);
+                                path_get_long(new_root);
                                 fs->root = *new_root;
                                 count++;
                         }
                         if (fs->pwd.dentry == old_root->dentry
                             && fs->pwd.mnt == old_root->mnt) {
-                                path_get(new_root);
+                                path_get_long(new_root);
                                 fs->pwd = *new_root;
                                 count++;
                         }
@@ -76,13 +76,13 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
         } while_each_thread(g, p);
         read_unlock(&tasklist_lock);
         while (count--)
-                path_put(old_root);
+                path_put_long(old_root);
 }
 
 void free_fs_struct(struct fs_struct *fs)
 {
-        path_put(&fs->root);
-        path_put(&fs->pwd);
+        path_put_long(&fs->root);
+        path_put_long(&fs->pwd);
         kmem_cache_free(fs_cachep, fs);
 }
 
@@ -115,7 +115,13 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old)
                 spin_lock_init(&fs->lock);
                 seqcount_init(&fs->seq);
                 fs->umask = old->umask;
-                get_fs_root_and_pwd(old, &fs->root, &fs->pwd);
+
+                spin_lock(&old->lock);
+                fs->root = old->root;
+                path_get_long(&fs->root);
+                fs->pwd = old->pwd;
+                path_get_long(&fs->pwd);
+                spin_unlock(&old->lock);
         }
         return fs;
 }
diff --git a/fs/internal.h b/fs/internal.h
index e43b9a4dbf4e..9687c2ee2735 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -63,6 +63,7 @@ extern int copy_mount_string(const void __user *, char **);
 
 extern void free_vfsmnt(struct vfsmount *);
 extern struct vfsmount *alloc_vfsmnt(const char *);
+extern unsigned int mnt_get_count(struct vfsmount *mnt);
 extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
 extern void mnt_set_mountpoint(struct vfsmount *, struct dentry *,
                                 struct vfsmount *);
diff --git a/fs/namei.c b/fs/namei.c
index 4e957bf744ae..19433cdba011 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -368,6 +368,18 @@ void path_get(struct path *path)
 EXPORT_SYMBOL(path_get);
 
 /**
+ * path_get_long - get a long reference to a path
+ * @path: path to get the reference to
+ *
+ * Given a path increment the reference count to the dentry and the vfsmount.
+ */
+void path_get_long(struct path *path)
+{
+        mntget_long(path->mnt);
+        dget(path->dentry);
+}
+
+/**
  * path_put - put a reference to a path
  * @path: path to put the reference to
  *
@@ -381,6 +393,18 @@ void path_put(struct path *path)
 EXPORT_SYMBOL(path_put);
 
 /**
+ * path_put_long - put a long reference to a path
+ * @path: path to put the reference to
+ *
+ * Given a path decrement the reference count to the dentry and the vfsmount.
+ */
+void path_put_long(struct path *path)
+{
+        dput(path->dentry);
+        mntput_long(path->mnt);
+}
+
+/**
  * nameidata_drop_rcu - drop this nameidata out of rcu-walk
  * @nd: nameidata pathwalk data to drop
  * @Returns: 0 on success, -ECHLID on failure
diff --git a/fs/namespace.c b/fs/namespace.c
index 03b82350f020..3ddfd9046c44 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -138,6 +138,64 @@ void mnt_release_group_id(struct vfsmount *mnt)
         mnt->mnt_group_id = 0;
 }
 
+/*
+ * vfsmount lock must be held for read
+ */
+static inline void mnt_add_count(struct vfsmount *mnt, int n)
+{
+#ifdef CONFIG_SMP
+        this_cpu_add(mnt->mnt_pcp->mnt_count, n);
+#else
+        preempt_disable();
+        mnt->mnt_count += n;
+        preempt_enable();
+#endif
+}
+
+static inline void mnt_set_count(struct vfsmount *mnt, int n)
+{
+#ifdef CONFIG_SMP
+        this_cpu_write(mnt->mnt_pcp->mnt_count, n);
+#else
+        mnt->mnt_count = n;
+#endif
+}
+
+/*
+ * vfsmount lock must be held for read
+ */
+static inline void mnt_inc_count(struct vfsmount *mnt)
+{
+        mnt_add_count(mnt, 1);
+}
+
+/*
+ * vfsmount lock must be held for read
+ */
+static inline void mnt_dec_count(struct vfsmount *mnt)
+{
+        mnt_add_count(mnt, -1);
+}
+
+/*
+ * vfsmount lock must be held for write
+ */
+unsigned int mnt_get_count(struct vfsmount *mnt)
+{
+#ifdef CONFIG_SMP
+        unsigned int count = atomic_read(&mnt->mnt_longrefs);
+        int cpu;
+
+        for_each_possible_cpu(cpu) {
+                count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count;
+        }
+
+        return count;
+#else
+        return mnt->mnt_count;
+#endif
+}
+
 struct vfsmount *alloc_vfsmnt(const char *name)
 {
         struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
@@ -154,7 +212,17 @@ struct vfsmount *alloc_vfsmnt(const char *name)
                                 goto out_free_id;
                 }
 
-                atomic_set(&mnt->mnt_count, 1);
+#ifdef CONFIG_SMP
+                mnt->mnt_pcp = alloc_percpu(struct mnt_pcp);
+                if (!mnt->mnt_pcp)
+                        goto out_free_devname;
+
+                atomic_set(&mnt->mnt_longrefs, 1);
+#else
+                mnt->mnt_count = 1;
+                mnt->mnt_writers = 0;
+#endif
+
                 INIT_LIST_HEAD(&mnt->mnt_hash);
                 INIT_LIST_HEAD(&mnt->mnt_child);
                 INIT_LIST_HEAD(&mnt->mnt_mounts);
@@ -166,13 +234,6 @@ struct vfsmount *alloc_vfsmnt(const char *name)
 #ifdef CONFIG_FSNOTIFY
                 INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks);
 #endif
-#ifdef CONFIG_SMP
-                mnt->mnt_writers = alloc_percpu(int);
-                if (!mnt->mnt_writers)
-                        goto out_free_devname;
-#else
-                mnt->mnt_writers = 0;
-#endif
         }
         return mnt;
 
@@ -219,7 +280,7 @@ EXPORT_SYMBOL_GPL(__mnt_is_readonly);
 static inline void mnt_inc_writers(struct vfsmount *mnt)
 {
 #ifdef CONFIG_SMP
-        (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))++;
+        this_cpu_inc(mnt->mnt_pcp->mnt_writers);
 #else
         mnt->mnt_writers++;
 #endif
@@ -228,7 +289,7 @@ static inline void mnt_inc_writers(struct vfsmount *mnt)
 static inline void mnt_dec_writers(struct vfsmount *mnt)
 {
 #ifdef CONFIG_SMP
-        (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))--;
+        this_cpu_dec(mnt->mnt_pcp->mnt_writers);
 #else
         mnt->mnt_writers--;
 #endif
@@ -241,7 +302,7 @@ static unsigned int mnt_get_writers(struct vfsmount *mnt)
         int cpu;
 
         for_each_possible_cpu(cpu) {
-                count += *per_cpu_ptr(mnt->mnt_writers, cpu);
+                count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers;
         }
 
         return count;
@@ -418,7 +479,7 @@ void free_vfsmnt(struct vfsmount *mnt)
         kfree(mnt->mnt_devname);
         mnt_free_id(mnt);
 #ifdef CONFIG_SMP
-        free_percpu(mnt->mnt_writers);
+        free_percpu(mnt->mnt_pcp);
 #endif
         kmem_cache_free(mnt_cache, mnt);
 }
@@ -652,9 +713,10 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
         return NULL;
 }
 
-static inline void __mntput(struct vfsmount *mnt)
+static inline void mntfree(struct vfsmount *mnt)
 {
         struct super_block *sb = mnt->mnt_sb;
+
         /*
          * This probably indicates that somebody messed
          * up a mnt_want/drop_write() pair.  If this
@@ -662,8 +724,8 @@ static inline void __mntput(struct vfsmount *mnt)
          * to make r/w->r/o transitions.
          */
         /*
-         * atomic_dec_and_lock() used to deal with ->mnt_count decrements
-         * provides barriers, so mnt_get_writers() below is safe.  AV
+         * The locking used to deal with mnt_count decrement provides barriers,
+         * so mnt_get_writers() below is safe.
          */
         WARN_ON(mnt_get_writers(mnt));
         fsnotify_vfsmount_delete(mnt);
@@ -672,28 +734,113 @@ static inline void __mntput(struct vfsmount *mnt)
         deactivate_super(sb);
 }
 
-void mntput_no_expire(struct vfsmount *mnt)
-{
-repeat:
-        if (atomic_add_unless(&mnt->mnt_count, -1, 1))
-                return;
+#ifdef CONFIG_SMP
+static inline void __mntput(struct vfsmount *mnt, int longrefs)
+{
+        if (!longrefs) {
+put_again:
+                br_read_lock(vfsmount_lock);
+                if (likely(atomic_read(&mnt->mnt_longrefs))) {
+                        mnt_dec_count(mnt);
+                        br_read_unlock(vfsmount_lock);
+                        return;
+                }
+                br_read_unlock(vfsmount_lock);
+        } else {
+                BUG_ON(!atomic_read(&mnt->mnt_longrefs));
+                if (atomic_add_unless(&mnt->mnt_longrefs, -1, 1))
+                        return;
+        }
+
         br_write_lock(vfsmount_lock);
-        if (!atomic_dec_and_test(&mnt->mnt_count)) {
+        if (!longrefs)
+                mnt_dec_count(mnt);
+        else
+                atomic_dec(&mnt->mnt_longrefs);
+        if (mnt_get_count(mnt)) {
                 br_write_unlock(vfsmount_lock);
                 return;
         }
-        if (likely(!mnt->mnt_pinned)) {
+        if (unlikely(mnt->mnt_pinned)) {
+                mnt_add_count(mnt, mnt->mnt_pinned + 1);
+                mnt->mnt_pinned = 0;
                 br_write_unlock(vfsmount_lock);
-                __mntput(mnt);
+                acct_auto_close_mnt(mnt);
+                goto put_again;
+        }
+        br_write_unlock(vfsmount_lock);
+        mntfree(mnt);
+}
+#else
+static inline void __mntput(struct vfsmount *mnt, int longrefs)
+{
+put_again:
+        mnt_dec_count(mnt);
+        if (likely(mnt_get_count(mnt)))
                 return;
+        br_write_lock(vfsmount_lock);
+        if (unlikely(mnt->mnt_pinned)) {
+                mnt_add_count(mnt, mnt->mnt_pinned + 1);
+                mnt->mnt_pinned = 0;
+                br_write_unlock(vfsmount_lock);
+                acct_auto_close_mnt(mnt);
+                goto put_again;
         }
-        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;
+        mntfree(mnt);
+}
+#endif
+
+static void mntput_no_expire(struct vfsmount *mnt)
+{
+        __mntput(mnt, 0);
+}
+
+void mntput(struct vfsmount *mnt)
+{
+        if (mnt) {
+                /* avoid cacheline pingpong, hope gcc doesn't get "smart" */
+                if (unlikely(mnt->mnt_expiry_mark))
+                        mnt->mnt_expiry_mark = 0;
+                __mntput(mnt, 0);
+        }
+}
+EXPORT_SYMBOL(mntput);
+
+struct vfsmount *mntget(struct vfsmount *mnt)
+{
+        if (mnt)
+                mnt_inc_count(mnt);
+        return mnt;
+}
+EXPORT_SYMBOL(mntget);
+
+void mntput_long(struct vfsmount *mnt)
+{
+#ifdef CONFIG_SMP
+        if (mnt) {
+                /* avoid cacheline pingpong, hope gcc doesn't get "smart" */
+                if (unlikely(mnt->mnt_expiry_mark))
+                        mnt->mnt_expiry_mark = 0;
+                __mntput(mnt, 1);
+        }
+#else
+        mntput(mnt);
+#endif
 }
-EXPORT_SYMBOL(mntput_no_expire);
+EXPORT_SYMBOL(mntput_long);
+
+struct vfsmount *mntget_long(struct vfsmount *mnt)
+{
+#ifdef CONFIG_SMP
+        if (mnt)
+                atomic_inc(&mnt->mnt_longrefs);
+        return mnt;
+#else
+        return mntget(mnt);
+#endif
+}
+EXPORT_SYMBOL(mntget_long);
 
 void mnt_pin(struct vfsmount *mnt)
 {
@@ -701,19 +848,17 @@ void mnt_pin(struct vfsmount *mnt)
         mnt->mnt_pinned++;
         br_write_unlock(vfsmount_lock);
 }
-
 EXPORT_SYMBOL(mnt_pin);
 
 void mnt_unpin(struct vfsmount *mnt)
 {
         br_write_lock(vfsmount_lock);
         if (mnt->mnt_pinned) {
-                atomic_inc(&mnt->mnt_count);
+                mnt_inc_count(mnt);
                 mnt->mnt_pinned--;
         }
         br_write_unlock(vfsmount_lock);
 }
-
 EXPORT_SYMBOL(mnt_unpin);
 
 static inline void mangle(struct seq_file *m, const char *s)
@@ -1008,12 +1153,13 @@ int may_umount_tree(struct vfsmount *mnt)
         int minimum_refs = 0;
         struct vfsmount *p;
 
-        br_read_lock(vfsmount_lock);
+        /* write lock needed for mnt_get_count */
+        br_write_lock(vfsmount_lock);
         for (p = mnt; p; p = next_mnt(p, mnt)) {
-                actual_refs += atomic_read(&p->mnt_count);
+                actual_refs += mnt_get_count(p);
                 minimum_refs += 2;
         }
-        br_read_unlock(vfsmount_lock);
+        br_write_unlock(vfsmount_lock);
 
         if (actual_refs > minimum_refs)
                 return 0;
@@ -1040,10 +1186,10 @@ int may_umount(struct vfsmount *mnt)
 {
         int ret = 1;
         down_read(&namespace_sem);
-        br_read_lock(vfsmount_lock);
+        br_write_lock(vfsmount_lock);
         if (propagate_mount_busy(mnt, 2))
                 ret = 0;
-        br_read_unlock(vfsmount_lock);
+        br_write_unlock(vfsmount_lock);
         up_read(&namespace_sem);
         return ret;
 }
@@ -1070,7 +1216,7 @@ void release_mounts(struct list_head *head)
                         dput(dentry);
                         mntput(m);
                 }
-                mntput(mnt);
+                mntput_long(mnt);
         }
 }
 
@@ -1125,8 +1271,16 @@ static int do_umount(struct vfsmount *mnt, int flags)
                     flags & (MNT_FORCE | MNT_DETACH))
                         return -EINVAL;
 
-                if (atomic_read(&mnt->mnt_count) != 2)
+                /*
+                 * probably don't strictly need the lock here if we examined
+                 * all race cases, but it's a slowpath.
+                 */
+                br_write_lock(vfsmount_lock);
+                if (mnt_get_count(mnt) != 2) {
+                        br_write_lock(vfsmount_lock);
                         return -EBUSY;
+                }
+                br_write_unlock(vfsmount_lock);
 
                 if (!xchg(&mnt->mnt_expiry_mark, 1))
                         return -EAGAIN;
@@ -1815,7 +1969,7 @@ int do_add_mount(struct vfsmount *newmnt, struct path *path,
 
 unlock:
         up_write(&namespace_sem);
-        mntput(newmnt);
+        mntput_long(newmnt);
         return err;
 }
 
@@ -2148,11 +2302,11 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
                 if (fs) {
                         if (p == fs->root.mnt) {
                                 rootmnt = p;
-                                fs->root.mnt = mntget(q);
+                                fs->root.mnt = mntget_long(q);
                         }
                         if (p == fs->pwd.mnt) {
                                 pwdmnt = p;
-                                fs->pwd.mnt = mntget(q);
+                                fs->pwd.mnt = mntget_long(q);
                         }
                 }
                 p = next_mnt(p, mnt_ns->root);
@@ -2161,9 +2315,9 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
         up_write(&namespace_sem);
 
         if (rootmnt)
-                mntput(rootmnt);
+                mntput_long(rootmnt);
         if (pwdmnt)
-                mntput(pwdmnt);
+                mntput_long(pwdmnt);
 
         return new_ns;
 }
@@ -2350,6 +2504,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
         touch_mnt_namespace(current->nsproxy->mnt_ns);
         br_write_unlock(vfsmount_lock);
         chroot_fs_refs(&root, &new);
+
         error = 0;
         path_put(&root_parent);
         path_put(&parent_path);
@@ -2376,6 +2531,7 @@ static void __init init_mount_tree(void)
         mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
         if (IS_ERR(mnt))
                 panic("Can't create rootfs");
+
         ns = create_mnt_ns(mnt);
         if (IS_ERR(ns))
                 panic("Can't allocate initial namespace");
diff --git a/fs/pipe.c b/fs/pipe.c
index cfe3a7f2ee21..68f1f8e4e23b 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1292,7 +1292,7 @@ static int __init init_pipe_fs(void)
 static void __exit exit_pipe_fs(void)
 {
         unregister_filesystem(&pipe_fs_type);
-        mntput(pipe_mnt);
+        mntput_long(pipe_mnt);
 }
 
 fs_initcall(init_pipe_fs);
diff --git a/fs/pnode.c b/fs/pnode.c
index 8066b8dd748f..d42514e32380 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -288,7 +288,7 @@ out:
  */
 static inline int do_refcount_check(struct vfsmount *mnt, int count)
 {
-        int mycount = atomic_read(&mnt->mnt_count) - mnt->mnt_ghosts;
+        int mycount = mnt_get_count(mnt) - mnt->mnt_ghosts;
         return (mycount > count);
 }
 
@@ -300,7 +300,7 @@ static inline int do_refcount_check(struct vfsmount *mnt, int count)
  * Check if any of these mounts that **do not have submounts**
  * have more references than 'refcnt'. If so return busy.
  *
- * vfsmount lock must be held for read or write
+ * vfsmount lock must be held for write
  */
 int propagate_mount_busy(struct vfsmount *mnt, int refcnt)
 {
diff --git a/fs/super.c b/fs/super.c
index 968ba013011a..823e061faa87 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1140,7 +1140,7 @@ static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
         return mnt;
 
  err:
-        mntput(mnt);
+        mntput_long(mnt);
         return ERR_PTR(err);
 }
 
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 5e7a59408dd4..1869ea24a739 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -13,6 +13,7 @@
 #include <linux/list.h>
 #include <linux/nodemask.h>
 #include <linux/spinlock.h>
+#include <linux/seqlock.h>
 #include <asm/atomic.h>
 
 struct super_block;
@@ -46,12 +47,24 @@ struct mnt_namespace;
 
 #define MNT_INTERNAL    0x4000
 
+struct mnt_pcp {
+        int mnt_count;
+        int mnt_writers;
+};
+
 struct vfsmount {
         struct list_head mnt_hash;
         struct vfsmount *mnt_parent;    /* fs we are mounted on */
         struct dentry *mnt_mountpoint;  /* dentry of mountpoint */
         struct dentry *mnt_root;        /* root of the mounted tree */
         struct super_block *mnt_sb;     /* pointer to superblock */
+#ifdef CONFIG_SMP
+        struct mnt_pcp __percpu *mnt_pcp;
+        atomic_t mnt_longrefs;
+#else
+        int mnt_count;
+        int mnt_writers;
+#endif
         struct list_head mnt_mounts;    /* list of children, anchored here */
         struct list_head mnt_child;     /* and going through their mnt_child */
         int mnt_flags;
@@ -70,57 +83,25 @@ struct vfsmount {
         struct mnt_namespace *mnt_ns;   /* containing namespace */
         int mnt_id;                     /* mount identifier */
         int mnt_group_id;               /* peer group identifier */
-        /*
-         * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
-         * to let these frequently modified fields in a separate cache line
-         * (so that reads of mnt_flags wont ping-pong on SMP machines)
-         */
-        atomic_t mnt_count;
         int mnt_expiry_mark;            /* true if marked for expiry */
         int mnt_pinned;
         int mnt_ghosts;
-#ifdef CONFIG_SMP
-        int __percpu *mnt_writers;
-#else
-        int mnt_writers;
-#endif
 };
 
-static inline int *get_mnt_writers_ptr(struct vfsmount *mnt)
-{
-#ifdef CONFIG_SMP
-        return mnt->mnt_writers;
-#else
-        return &mnt->mnt_writers;
-#endif
-}
-
-static inline struct vfsmount *mntget(struct vfsmount *mnt)
-{
-        if (mnt)
-                atomic_inc(&mnt->mnt_count);
-        return mnt;
-}
-
 struct file; /* forward dec */
 
 extern int mnt_want_write(struct vfsmount *mnt);
 extern int mnt_want_write_file(struct file *file);
 extern int mnt_clone_write(struct vfsmount *mnt);
 extern void mnt_drop_write(struct vfsmount *mnt);
-extern void mntput_no_expire(struct vfsmount *mnt);
+extern void mntput(struct vfsmount *mnt);
+extern struct vfsmount *mntget(struct vfsmount *mnt);
+extern void mntput_long(struct vfsmount *mnt);
+extern struct vfsmount *mntget_long(struct vfsmount *mnt);
 extern void mnt_pin(struct vfsmount *mnt);
 extern void mnt_unpin(struct vfsmount *mnt);
 extern int __mnt_is_readonly(struct vfsmount *mnt);
 
-static inline void mntput(struct vfsmount *mnt)
-{
-        if (mnt) {
-                mnt->mnt_expiry_mark = 0;
-                mntput_no_expire(mnt);
-        }
-}
-
 extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
                                       const char *name, void *data);
 
diff --git a/include/linux/path.h b/include/linux/path.h
index edc98dec6266..a581e8c06533 100644
--- a/include/linux/path.h
+++ b/include/linux/path.h
@@ -10,7 +10,9 @@ struct path {
 };
 
 extern void path_get(struct path *);
+extern void path_get_long(struct path *);
 extern void path_put(struct path *);
+extern void path_put_long(struct path *);
 
 static inline int path_equal(const struct path *path1, const struct path *path2)
 {
diff --git a/net/socket.c b/net/socket.c
index 0ee74c325320..815bba3d2fe0 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2390,6 +2390,8 @@ EXPORT_SYMBOL(sock_unregister);
 
 static int __init sock_init(void)
 {
+        int err;
+
         /*
          *      Initialize sock SLAB cache.
          */
@@ -2406,8 +2408,15 @@ static int __init sock_init(void)
          */
 
         init_inodecache();
-        register_filesystem(&sock_fs_type);
+
+        err = register_filesystem(&sock_fs_type);
+        if (err)
+                goto out_fs;
         sock_mnt = kern_mount(&sock_fs_type);
+        if (IS_ERR(sock_mnt)) {
+                err = PTR_ERR(sock_mnt);
+                goto out_mount;
+        }
 
         /* The real protocol initialization is performed in later initcalls.
          */
@@ -2420,7 +2429,13 @@ static int __init sock_init(void)
         skb_timestamping_init();
 #endif
 
-        return 0;
+out:
+        return err;
+
+out_mount:
+        unregister_filesystem(&sock_fs_type);
+out_fs:
+        goto out;
 }
 
 core_initcall(sock_init);       /* early initcall */