Message-Id: <1197254546424-git-send-email-ezk@cs.sunysb.edu>
Date:	Sun,  9 Dec 2007 21:41:52 -0500
From:	Erez Zadok <ezk@...sunysb.edu>
To:	hch@...radead.org, viro@....linux.org.uk, akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Erez Zadok <ezk@...sunysb.edu>
Subject: [PATCH 19/42] Unionfs: readdir helper functions

Includes whiteout handling for directories.

Signed-off-by: Erez Zadok <ezk@...sunysb.edu>
---
 fs/unionfs/dirhelper.c |  272 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 272 insertions(+), 0 deletions(-)
 create mode 100644 fs/unionfs/dirhelper.c

diff --git a/fs/unionfs/dirhelper.c b/fs/unionfs/dirhelper.c
new file mode 100644
index 0000000..2e52fc3
--- /dev/null
+++ b/fs/unionfs/dirhelper.c
@@ -0,0 +1,272 @@
+/*
+ * Copyright (c) 2003-2007 Erez Zadok
+ * Copyright (c) 2003-2006 Charles P. Wright
+ * Copyright (c) 2005-2007 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) 2003-2007 Stony Brook University
+ * Copyright (c) 2003-2007 The Research Foundation of SUNY
+ *
+ * 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"
+
+/*
+ * Delete all of the whiteouts in a given directory for rmdir.
+ *
+ * lower directory inode should be locked
+ */
+int do_delete_whiteouts(struct dentry *dentry, int bindex,
+			struct unionfs_dir_state *namelist)
+{
+	int err = 0;
+	struct dentry *lower_dir_dentry = NULL;
+	struct dentry *lower_dentry;
+	char *name = NULL, *p;
+	struct inode *lower_dir;
+	int i;
+	struct list_head *pos;
+	struct filldir_node *cursor;
+
+	/* Find out lower parent dentry */
+	lower_dir_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+	BUG_ON(!S_ISDIR(lower_dir_dentry->d_inode->i_mode));
+	lower_dir = lower_dir_dentry->d_inode;
+	BUG_ON(!S_ISDIR(lower_dir->i_mode));
+
+	err = -ENOMEM;
+	name = __getname();
+	if (unlikely(!name))
+		goto out;
+	strcpy(name, UNIONFS_WHPFX);
+	p = name + UNIONFS_WHLEN;
+
+	err = 0;
+	for (i = 0; !err && i < namelist->size; i++) {
+		list_for_each(pos, &namelist->list[i]) {
+			cursor =
+				list_entry(pos, struct filldir_node,
+					   file_list);
+			/* Only operate on whiteouts in this branch. */
+			if (cursor->bindex != bindex)
+				continue;
+			if (!cursor->whiteout)
+				continue;
+
+			strcpy(p, cursor->name);
+			lower_dentry =
+				lookup_one_len(name, lower_dir_dentry,
+					       cursor->namelen +
+					       UNIONFS_WHLEN);
+			if (IS_ERR(lower_dentry)) {
+				err = PTR_ERR(lower_dentry);
+				break;
+			}
+			if (lower_dentry->d_inode)
+				err = vfs_unlink(lower_dir, lower_dentry);
+			dput(lower_dentry);
+			if (err)
+				break;
+		}
+	}
+
+	__putname(name);
+
+	/* After all of the removals, we should copy the attributes once. */
+	fsstack_copy_attr_times(dentry->d_inode, lower_dir_dentry->d_inode);
+
+out:
+	return err;
+}
+
+/* delete whiteouts in a dir (for rmdir operation) using sioq if necessary */
+int delete_whiteouts(struct dentry *dentry, int bindex,
+		     struct unionfs_dir_state *namelist)
+{
+	int err;
+	struct super_block *sb;
+	struct dentry *lower_dir_dentry;
+	struct inode *lower_dir;
+	struct sioq_args args;
+
+	sb = dentry->d_sb;
+
+	BUG_ON(!S_ISDIR(dentry->d_inode->i_mode));
+	BUG_ON(bindex < dbstart(dentry));
+	BUG_ON(bindex > dbend(dentry));
+	err = is_robranch_super(sb, bindex);
+	if (err)
+		goto out;
+
+	lower_dir_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+	BUG_ON(!S_ISDIR(lower_dir_dentry->d_inode->i_mode));
+	lower_dir = lower_dir_dentry->d_inode;
+	BUG_ON(!S_ISDIR(lower_dir->i_mode));
+
+	mutex_lock(&lower_dir->i_mutex);
+	if (!permission(lower_dir, MAY_WRITE | MAY_EXEC, NULL)) {
+		err = do_delete_whiteouts(dentry, bindex, namelist);
+	} else {
+		args.deletewh.namelist = namelist;
+		args.deletewh.dentry = dentry;
+		args.deletewh.bindex = bindex;
+		run_sioq(__delete_whiteouts, &args);
+		err = args.err;
+	}
+	mutex_unlock(&lower_dir->i_mutex);
+
+out:
+	return err;
+}
+
+#define RD_NONE 0
+#define RD_CHECK_EMPTY 1
+/* The callback structure for check_empty. */
+struct unionfs_rdutil_callback {
+	int err;
+	int filldir_called;
+	struct unionfs_dir_state *rdstate;
+	int mode;
+};
+
+/* This filldir function makes sure only whiteouts exist within a directory. */
+static int readdir_util_callback(void *dirent, const char *name, int namelen,
+				 loff_t offset, u64 ino, unsigned int d_type)
+{
+	int err = 0;
+	struct unionfs_rdutil_callback *buf = dirent;
+	int whiteout = 0;
+	struct filldir_node *found;
+
+	buf->filldir_called = 1;
+
+	if (name[0] == '.' && (namelen == 1 ||
+			       (name[1] == '.' && namelen == 2)))
+		goto out;
+
+	if (namelen > UNIONFS_WHLEN &&
+	    !strncmp(name, UNIONFS_WHPFX, UNIONFS_WHLEN)) {
+		namelen -= UNIONFS_WHLEN;
+		name += UNIONFS_WHLEN;
+		whiteout = 1;
+	}
+
+	found = find_filldir_node(buf->rdstate, name, namelen, whiteout);
+	/* If it was found in the table there was a previous whiteout. */
+	if (found)
+		goto out;
+
+	/*
+	 * if it wasn't found and isn't a whiteout, the directory isn't
+	 * empty.
+	 */
+	err = -ENOTEMPTY;
+	if ((buf->mode == RD_CHECK_EMPTY) && !whiteout)
+		goto out;
+
+	err = add_filldir_node(buf->rdstate, name, namelen,
+			       buf->rdstate->bindex, whiteout);
+
+out:
+	buf->err = err;
+	return err;
+}
+
+/* Is a directory logically empty? */
+int check_empty(struct dentry *dentry, struct unionfs_dir_state **namelist)
+{
+	int err = 0;
+	struct dentry *lower_dentry = NULL;
+	struct super_block *sb;
+	struct file *lower_file;
+	struct unionfs_rdutil_callback *buf = NULL;
+	int bindex, bstart, bend, bopaque;
+
+	sb = dentry->d_sb;
+
+
+	BUG_ON(!S_ISDIR(dentry->d_inode->i_mode));
+
+	err = unionfs_partial_lookup(dentry);
+	if (err)
+		goto out;
+
+	bstart = dbstart(dentry);
+	bend = dbend(dentry);
+	bopaque = dbopaque(dentry);
+	if (0 <= bopaque && bopaque < bend)
+		bend = bopaque;
+
+	buf = kmalloc(sizeof(struct unionfs_rdutil_callback), GFP_KERNEL);
+	if (unlikely(!buf)) {
+		err = -ENOMEM;
+		goto out;
+	}
+	buf->err = 0;
+	buf->mode = RD_CHECK_EMPTY;
+	buf->rdstate = alloc_rdstate(dentry->d_inode, bstart);
+	if (unlikely(!buf->rdstate)) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	/* Process the lower directories with rdutil_callback as a filldir. */
+	for (bindex = bstart; bindex <= bend; bindex++) {
+		lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+		if (!lower_dentry)
+			continue;
+		if (!lower_dentry->d_inode)
+			continue;
+		if (!S_ISDIR(lower_dentry->d_inode->i_mode))
+			continue;
+
+		dget(lower_dentry);
+		unionfs_mntget(dentry, bindex);
+		branchget(sb, bindex);
+		lower_file =
+			dentry_open(lower_dentry,
+				    unionfs_lower_mnt_idx(dentry, bindex),
+				    O_RDONLY);
+		if (IS_ERR(lower_file)) {
+			err = PTR_ERR(lower_file);
+			dput(lower_dentry);
+			branchput(sb, bindex);
+			goto out;
+		}
+
+		do {
+			buf->filldir_called = 0;
+			buf->rdstate->bindex = bindex;
+			err = vfs_readdir(lower_file,
+					  readdir_util_callback, buf);
+			if (buf->err)
+				err = buf->err;
+		} while ((err >= 0) && buf->filldir_called);
+
+		/* fput calls dput for lower_dentry */
+		fput(lower_file);
+		branchput(sb, bindex);
+
+		if (err < 0)
+			goto out;
+	}
+
+out:
+	if (buf) {
+		if (namelist && !err)
+			*namelist = buf->rdstate;
+		else if (buf->rdstate)
+			free_rdstate(buf->rdstate);
+		kfree(buf);
+	}
+
+
+	return err;
+}
-- 
1.5.2.2

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