[PATCH 21/22][RFC] Unionfs: Unlink

Josef Sipek
2006-09-01T02:02:14Z

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 | 179 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 179 insertions(+)

diff -Nur -x linux-2.6-git/Documentation/dontdiff linux-2.6-git/fs/unionfs/unlink.c linux-2.6-git-unionfs/fs/unionfs/unlink.c
--- linux-2.6-git/fs/unionfs/unlink.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6-git-unionfs/fs/unionfs/unlink.c 2006-08-31 19:04:01.000000000 -0400
@@ -0,0 +1,179 @@
+/*
+ * 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
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package.
+ *
+ * This Copyright notice must be kept intact and distributed with all sources.
+ */
+
+#include "union.h"
+
+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 = dtohd_index(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);
+ fist_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 = dtohd(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);
+
+ fist_copy_attr_times(dir, hidden_dir_dentry->d_inode);
+ /* propagate number of hard-links */
+ dentry->d_inode->i_nlink = 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) {
+#if 0
+ /* vfs_rmdir(our caller) unhashed the dentry. This will recover
+ * the Unionfs inode number for the directory itself, but the
+ * children are already lost. It seems that tmpfs manages its
+ * way around this by upping the refcount on everything.
+ *
+ * Even if we do this, we still lose the inode numbers of the
+ * children. The best way to fix this is to fix the VFS (or
+ * use persistent inode maps). */
+ if (d_unhashed(dentry))
+ d_rehash(dentry);
+#endif
+ 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;
+}
+