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>

fs/hpfs/namei.c

@@ -414,7 +414,6 @@ again:
 		mutex_unlock(&hpfs_i(inode)->i_parent_mutex);
 		dentry_unhash(dentry);
 		if (!d_unhashed(dentry)) {
-			dput(dentry);
 			hpfs_unlock(dir->i_sb);
 			return -ENOSPC;
 		}
@@ -422,7 +421,6 @@ again:
 		    !S_ISREG(inode->i_mode) ||
 		    get_write_access(inode)) {
 			d_rehash(dentry);
-			dput(dentry);
 		} else {
 			struct iattr newattrs;
 			/*printk("HPFS: truncating file before delete.\n");*/
@@ -430,7 +428,6 @@ again:
 			newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
 			err = notify_change(dentry, &newattrs);
 			put_write_access(inode);
-			dput(dentry);
 			if (!err)
 				goto again;
 		}

fs/namei.c

@@ -2545,10 +2545,9 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
  */
 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 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
 				dentry->d_inode->i_flags |= S_DEAD;
 				dont_mount(dentry);
 			}
-			dput(dentry);
 		}
 	}
 	mutex_unlock(&dentry->d_inode->i_mutex);
@@ -3002,7 +3000,6 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
 		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))

fs/reiserfs/xattr.c

@@ -105,7 +105,6 @@ static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
 	mutex_unlock(&dentry->d_inode->i_mutex);
 	if (!error)
 		d_delete(dentry);
-	dput(dentry);
 
 	return error;
 }