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Subject[PATCH 19/42] Unionfs: readdir helper functions
Date
Includes whiteout handling for directories.

Signed-off-by: Erez Zadok <ezk@cs.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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