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Subject[PATCH 22/24] Unionfs: Unlink
Date
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

This patch provides unlink functionality for Unionfs.

Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: David Quigley <dquigley@fsl.cs.sunysb.edu>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
---
fs/unionfs/unlink.c | 162 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 162 insertions(+), 0 deletions(-)
diff --git a/fs/unionfs/unlink.c b/fs/unionfs/unlink.c
new file mode 100644
index 0000000..844835f
--- /dev/null
+++ b/fs/unionfs/unlink.c
@@ -0,0 +1,162 @@
+/*
+ * Copyright (c) 2003-2006 Erez Zadok
+ * Copyright (c) 2003-2006 Charles P. Wright
+ * Copyright (c) 2005-2006 Josef 'Jeff' Sipek
+ * Copyright (c) 2005-2006 Junjiro Okajima
+ * Copyright (c) 2005 Arun M. Krishnakumar
+ * Copyright (c) 2004-2006 David P. Quigley
+ * Copyright (c) 2003-2004 Mohammad Nayyer Zubair
+ * Copyright (c) 2003 Puja Gupta
+ * Copyright (c) 2003 Harikesavan Krishnan
+ * Copyright (c) 2003-2006 Stony Brook University
+ * Copyright (c) 2003-2006 The Research Foundation of State University of New York
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "union.h"
+
+/* unlink a file by creating a whiteout */
+static int unionfs_unlink_whiteout(struct inode *dir, struct dentry *dentry)
+{
+ struct dentry *hidden_dentry;
+ struct dentry *hidden_dir_dentry;
+ int bindex;
+ int err = 0;
+
+ if ((err = unionfs_partial_lookup(dentry)))
+ goto out;
+
+ bindex = dbstart(dentry);
+
+ hidden_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!hidden_dentry)
+ goto out;
+
+ hidden_dir_dentry = lock_parent(hidden_dentry);
+
+ /* avoid destroying the hidden inode if the file is in use */
+ dget(hidden_dentry);
+ if (!(err = is_robranch_super(dentry->d_sb, bindex)))
+ err = vfs_unlink(hidden_dir_dentry->d_inode, hidden_dentry);
+ dput(hidden_dentry);
+ fsstack_copy_attr_times(dir, hidden_dir_dentry->d_inode);
+ unlock_dir(hidden_dir_dentry);
+
+ if (err && !IS_COPYUP_ERR(err))
+ goto out;
+
+ if (err) {
+ if (dbstart(dentry) == 0)
+ goto out;
+
+ err = create_whiteout(dentry, dbstart(dentry) - 1);
+ } else if (dbopaque(dentry) != -1)
+ /* There is a hidden lower-priority file with the same name. */
+ err = create_whiteout(dentry, dbopaque(dentry));
+ else
+ err = create_whiteout(dentry, dbstart(dentry));
+
+out:
+ if (!err)
+ dentry->d_inode->i_nlink--;
+
+ /* We don't want to leave negative leftover dentries for revalidate. */
+ if (!err && (dbopaque(dentry) != -1))
+ update_bstart(dentry);
+
+ return err;
+}
+
+int unionfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+ int err = 0;
+
+ lock_dentry(dentry);
+
+ err = unionfs_unlink_whiteout(dir, dentry);
+ /* call d_drop so the system "forgets" about us */
+ if (!err)
+ d_drop(dentry);
+
+ unlock_dentry(dentry);
+ return err;
+}
+
+static int unionfs_rmdir_first(struct inode *dir, struct dentry *dentry,
+ struct unionfs_dir_state *namelist)
+{
+ int err;
+ struct dentry *hidden_dentry;
+ struct dentry *hidden_dir_dentry = NULL;
+
+ /* Here we need to remove whiteout entries. */
+ err = delete_whiteouts(dentry, dbstart(dentry), namelist);
+ if (err)
+ goto out;
+
+ hidden_dentry = unionfs_lower_dentry(dentry);
+
+ hidden_dir_dentry = lock_parent(hidden_dentry);
+
+ /* avoid destroying the hidden inode if the file is in use */
+ dget(hidden_dentry);
+ if (!(err = is_robranch(dentry)))
+ err = vfs_rmdir(hidden_dir_dentry->d_inode, hidden_dentry);
+ dput(hidden_dentry);
+
+ fsstack_copy_attr_times(dir, hidden_dir_dentry->d_inode);
+ /* propagate number of hard-links */
+ dentry->d_inode->i_nlink = unionfs_get_nlinks(dentry->d_inode);
+
+out:
+ if (hidden_dir_dentry)
+ unlock_dir(hidden_dir_dentry);
+ return err;
+}
+
+int unionfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ int err = 0;
+ struct unionfs_dir_state *namelist = NULL;
+
+ lock_dentry(dentry);
+
+ /* check if this unionfs directory is empty or not */
+ err = check_empty(dentry, &namelist);
+ if (err)
+ goto out;
+
+ err = unionfs_rmdir_first(dir, dentry, namelist);
+ /* create whiteout */
+ if (!err)
+ err = create_whiteout(dentry, dbstart(dentry));
+ else {
+ int new_err;
+
+ if (dbstart(dentry) == 0)
+ goto out;
+
+ /* exit if the error returned was NOT -EROFS */
+ if (!IS_COPYUP_ERR(err))
+ goto out;
+
+ new_err = create_whiteout(dentry, dbstart(dentry) - 1);
+ if (new_err != -EEXIST)
+ err = new_err;
+ }
+
+out:
+ /* call d_drop so the system "forgets" about us */
+ if (!err)
+ d_drop(dentry);
+
+ if (namelist)
+ free_rdstate(namelist);
+
+ unlock_dentry(dentry);
+ return err;
+}
+
--
1.4.4.2
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