[PATCH 17/22][RFC] Unionfs: Miscellaneous helper functions

Josef Sipek
2006-09-01T01:58:22Z

From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

This patch contains miscellaneous helper functions used thoughout 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/subr.c | 179 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 179 insertions(+)

diff -Nur -x linux-2.6-git/Documentation/dontdiff linux-2.6-git/fs/unionfs/subr.c linux-2.6-git-unionfs/fs/unionfs/subr.c
--- linux-2.6-git/fs/unionfs/subr.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6-git-unionfs/fs/unionfs/subr.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"
+
+/* Pass an unionfs dentry and an index. It will try to create a whiteout
+ * for the filename in dentry, and will try in branch 'index'. On error,
+ * it will proceed to a branch to the left.
+ */
+int create_whiteout(struct dentry *dentry, int start)
+{
+ int bstart, bend, bindex;
+ struct dentry *hidden_dir_dentry;
+ struct dentry *hidden_dentry;
+ struct dentry *hidden_wh_dentry;
+ char *name = NULL;
+ int err = -EINVAL;
+
+ verify_locked(dentry);
+
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+
+ /* create dentry's whiteout equivalent */
+ name = alloc_whname(dentry->d_name.name, dentry->d_name.len);
+ if (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ for (bindex = start; bindex >= 0; bindex--) {
+ hidden_dentry = dtohd_index(dentry, bindex);
+
+ if (!hidden_dentry) {
+ /* if hidden dentry is not present, create the entire
+ * hidden dentry directory structure and go ahead.
+ * Since we want to just create whiteout, we only want
+ * the parent dentry, and hence get rid of this dentry.
+ */
+ hidden_dentry = create_parents(dentry->d_inode,
+ dentry, bindex);
+ if (!hidden_dentry || IS_ERR(hidden_dentry)) {
+ printk(KERN_DEBUG
+ "create_parents failed for bindex = %d\n",
+ bindex);
+ continue;
+ }
+ }
+ hidden_wh_dentry =
+ lookup_one_len(name, hidden_dentry->d_parent,
+ dentry->d_name.len + UNIONFS_WHLEN);
+ if (IS_ERR(hidden_wh_dentry))
+ continue;
+
+ /* The whiteout already exists. This used to be impossible, but
+ * now is possible because of opaqueness. */
+ if (hidden_wh_dentry->d_inode) {
+ dput(hidden_wh_dentry);
+ err = 0;
+ goto out;
+ }
+
+ hidden_dir_dentry = lock_parent(hidden_wh_dentry);
+ if (!(err = is_robranch_super(dentry->d_sb, bindex))) {
+ err =
+ vfs_create(hidden_dir_dentry->d_inode,
+ hidden_wh_dentry,
+ ~current->fs->umask & S_IRWXUGO, NULL);
+
+ }
+ unlock_dir(hidden_dir_dentry);
+ dput(hidden_wh_dentry);
+
+ if (!err)
+ break;
+
+ if (!IS_COPYUP_ERR(err))
+ break;
+ }
+
+ /* set dbopaque so that lookup will not proceed after this branch */
+ if (!err)
+ set_dbopaque(dentry, bindex);
+
+out:
+ kfree(name);
+ return err;
+}
+
+/* This is a helper function for rename, which ends up with hosed over dentries
+ * when it needs to revert. */
+int unionfs_refresh_hidden_dentry(struct dentry *dentry, int bindex)
+{
+ struct dentry *hidden_dentry;
+ struct dentry *hidden_parent;
+ int err = 0;
+
+ verify_locked(dentry);
+
+ lock_dentry(dentry->d_parent);
+ hidden_parent = dtohd_index(dentry->d_parent, bindex);
+ unlock_dentry(dentry->d_parent);
+
+ BUG_ON(!S_ISDIR(hidden_parent->d_inode->i_mode));
+
+ hidden_dentry =
+ lookup_one_len(dentry->d_name.name, hidden_parent,
+ dentry->d_name.len);
+ if (IS_ERR(hidden_dentry)) {
+ err = PTR_ERR(hidden_dentry);
+ goto out;
+ }
+
+ if (dtohd_index(dentry, bindex))
+ dput(dtohd_index(dentry, bindex));
+ if (itohi_index(dentry->d_inode, bindex)) {
+ iput(itohi_index(dentry->d_inode, bindex));
+ set_itohi_index(dentry->d_inode, bindex, NULL);
+ }
+ if (!hidden_dentry->d_inode) {
+ dput(hidden_dentry);
+ set_dtohd_index(dentry, bindex, NULL);
+ } else {
+ set_dtohd_index(dentry, bindex, hidden_dentry);
+ set_itohi_index(dentry->d_inode, bindex,
+ igrab(hidden_dentry->d_inode));
+ }
+
+out:
+ return err;
+}
+
+int make_dir_opaque(struct dentry *dentry, int bindex)
+{
+ int err = 0;
+ struct dentry *hidden_dentry, *diropq;
+ struct inode *hidden_dir;
+
+ hidden_dentry = dtohd_index(dentry, bindex);
+ hidden_dir = hidden_dentry->d_inode;
+ BUG_ON(!S_ISDIR(dentry->d_inode->i_mode)
+ || !S_ISDIR(hidden_dir->i_mode));
+
+ mutex_lock(&hidden_dir->i_mutex);
+ diropq = lookup_one_len(UNIONFS_DIR_OPAQUE, hidden_dentry,
+ sizeof(UNIONFS_DIR_OPAQUE) - 1);
+ if (IS_ERR(diropq)) {
+ err = PTR_ERR(diropq);
+ goto out;
+ }
+
+ if (!diropq->d_inode)
+ err = vfs_create(hidden_dir, diropq, S_IRUGO, NULL);
+ if (!err)
+ set_dbopaque(dentry, bindex);
+
+ dput(diropq);
+
+out:
+ mutex_unlock(&hidden_dir->i_mutex);
+ return err;
+}
+