vfs: remove dget() from dentry_unhash()

This serves no useful purpose that I can discern.  All callers (rename,
rmdir) hold their own reference to the dentry.

A quick audit of all file systems showed no relevant checks on the value
of d_count in vfs_rmdir/vfs_rename_dir paths.

Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namei.c b/fs/namei.c
index af51199..8d11187 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2545,10 +2545,9 @@
  */
 void dentry_unhash(struct dentry *dentry)
 {
-	dget(dentry);
 	shrink_dcache_parent(dentry);
 	spin_lock(&dentry->d_lock);
-	if (dentry->d_count == 2)
+	if (dentry->d_count == 1)
 		__d_drop(dentry);
 	spin_unlock(&dentry->d_lock);
 }
@@ -2575,7 +2574,6 @@
 				dentry->d_inode->i_flags |= S_DEAD;
 				dont_mount(dentry);
 			}
-			dput(dentry);
 		}
 	}
 	mutex_unlock(&dentry->d_inode->i_mutex);
@@ -3002,7 +3000,6 @@
 		mutex_unlock(&target->i_mutex);
 		if (d_unhashed(new_dentry))
 			d_rehash(new_dentry);
-		dput(new_dentry);
 	}
 	if (!error)
 		if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))