1 files changed, 41 insertions, 23 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 2fa9fdf7d6f5..1d83302f30c3 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -172,7 +172,7 @@ clone_mnt(struct vfsmount *old, struct dentry *root)
         return mnt;
 }
 
-void __mntput(struct vfsmount *mnt)
+static inline void __mntput(struct vfsmount *mnt)
 {
         struct super_block *sb = mnt->mnt_sb;
         dput(mnt->mnt_root);
@@ -180,7 +180,46 @@ void __mntput(struct vfsmount *mnt)
         deactivate_super(sb);
 }
 
-EXPORT_SYMBOL(__mntput);
+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);
+                security_sb_umount_close(mnt);
+                goto repeat;
+        }
+}
+
+EXPORT_SYMBOL(mntput_no_expire);
+
+void mnt_pin(struct vfsmount *mnt)
+{
+        spin_lock(&vfsmount_lock);
+        mnt->mnt_pinned++;
+        spin_unlock(&vfsmount_lock);
+}
+
+EXPORT_SYMBOL(mnt_pin);
+
+void mnt_unpin(struct vfsmount *mnt)
+{
+        spin_lock(&vfsmount_lock);
+        if (mnt->mnt_pinned) {
+                atomic_inc(&mnt->mnt_count);
+                mnt->mnt_pinned--;
+        }
+        spin_unlock(&vfsmount_lock);
+}
+
+EXPORT_SYMBOL(mnt_unpin);
 
 /* iterator */
 static void *m_start(struct seq_file *m, loff_t *pos)
@@ -435,16 +474,6 @@ static int do_umount(struct vfsmount *mnt, int flags)
         down_write(&current->namespace->sem);
         spin_lock(&vfsmount_lock);
 
-        if (atomic_read(&sb->s_active) == 1) {
-                /* last instance - try to be smart */
-                spin_unlock(&vfsmount_lock);
-                lock_kernel();
-                DQUOT_OFF(sb);
-                acct_auto_close(sb);
-                unlock_kernel();
-                security_sb_umount_close(mnt);
-                spin_lock(&vfsmount_lock);
-        }
         retval = -EBUSY;
         if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) {
                 if (!list_empty(&mnt->mnt_list))
@@ -850,17 +879,6 @@ static void expire_mount(struct vfsmount *mnt, struct list_head *mounts)
                 detach_mnt(mnt, &old_nd);
                 spin_unlock(&vfsmount_lock);
                 path_release(&old_nd);
-
-                /*
-                 * Now lay it to rest if this was the last ref on the superblock
-                 */
-                if (atomic_read(&mnt->mnt_sb->s_active) == 1) {
-                        /* last instance - try to be smart */
-                        lock_kernel();
-                        DQUOT_OFF(mnt->mnt_sb);
-                        acct_auto_close(mnt->mnt_sb);
-                        unlock_kernel();
-                }
                 mntput(mnt);
         } else {
                 /*