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    Subject[PATCH 14/29] Unionfs: readdir helper functions
    Date
    Includes whiteout handling for directories.

    Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
    ---
    fs/unionfs/dirhelper.c | 267 ++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 267 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..4b73bb6
    --- /dev/null
    +++ b/fs/unionfs/dirhelper.c
    @@ -0,0 +1,267 @@
    +/*
    + * 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));
    +
    + 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;
    + }
    +
    +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 vfsmount *mnt;
    + 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);
    + mnt = unionfs_mntget(dentry, bindex);
    + branchget(sb, bindex);
    + lower_file = dentry_open(lower_dentry, mnt, O_RDONLY);
    + if (IS_ERR(lower_file)) {
    + err = PTR_ERR(lower_file);
    + 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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